Development of a lesson on physics on the topic "Electric current in semiconductors." Physics lesson on the topic "Semiconductors. Electric current through contact semiconductors P-n types. Semiconductor diode. Transistors" Open lesson in physics semiconductors

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Ministry of Science and Education

Department of "IIVT"

Explanatory note

To the course work

Organization and methods of industrial training on the subject: Materials Science and Electradiocratic

On the topic: semiconductor materials

Introduction

I. . In modern technique, metals and alloys are very widely used, as well as electrical materials. Modern radio electronic instrument agent has reached such a stage of development when important parameters devices depend not so much from circum solutionshow many from the used electrody materials and perfection technological processes their manufacturing. The subject material science consists of five sections. The first section is called general About metals and alloys.

Metal is a solid.

Alloy is a compound of 2 and more chemical elements

Component are substances component alloy.

II. Conductive materials are materials that have low resistance.

III. Dielectric materials

Dielectrics are insulating materials.

IV. Semiconductor materials are materials that have a small amount of energies during operation.

V. Magnetic materials - possessing the properties of attracting.

Structural steel and alloys

Constructive are called steel, intended for the manufacture of machine parts (machine-building steel), structures and structures (construction steel).

Carbon structural steel

Carbon structural steel are divided into ordinary quality and high-quality steel.

Ordinary steel Quality is made by the following brands of St0, St1, St2, ..., St6 (with increasing the room increases the carbon content). ST4 - carbon 0.18-0.27%, manganese 0.4-0.7%.

With an increase in the conditional number of the brand of steel, the tensile strength (B) and fluidity (0.2) increases and the plasticity decreases (). ST3SP has B \u003d 380490MPa, 0.2 \u003d 210250MPa, \u003d 2522%.

High-quality carbonistic Steels are paid in compliance with more stringent conditions with respect to the composition of the charge and melting and casting. S.<=0.04%, P<=0.0350.04%, а также меньшее содержание неметаллических включений.

High-quality carbon steel marked with numbers 08, 10, 15, ..., 85, which indicate the average carbon content in hundredths of the percent.

Low carbon steel (FROM<0.25%) 05кп, 08, 07кп, 10, 10кп обладают высокой прочностью и высокой пластичностью. в =330340МПа, 0.2 =230280МПа, =3331%.

Medium carbon steel (0.3-0.5% c) 30, 35, ..., 55 are used after normalization, improvement and surface hardening for a wide variety of details in all industries. These steel compared to low carbons have higher strength at lower plasticity (B \u003d 500600MP, 0.2 \u003d 300360MPa, \u003d 2116%). In this regard, they should be used for the manufacture of small parts or larger, but not requiring end-to-end calcination.

Steel with high carbon content (0.6-0.85% c) 60, 65, ..., 85 have high strength, wear resistance and elastic properties. From these steels, springs and springs, spindles, castle washers, rolling rolls, etc. are manufactured.

Alloy structural steel

Steel, in which the total amount of the content of alloying elements does not exceed 2.5%, refer to low-alloyed, containing 2.5-10% to doped, and more than 10% to high-alloyed (iron content of more than 45%).

The most widespread use in construction was low alloy steel, and in mechanical engineering - alloyed steel.

Alloyed structural steel marked with numbers and letters. The two-digit figures given at the beginning of the brand indicate the average carbon content in hundredths of the percent, the letter to the right of the numbers denote the doping element.

Building low alloy steel

Low dopeds are called steel, containing no more than 0.22% C and a relatively small number of non-effective alloying elements: up to 1.8% Mn, up to 1.2% Si, up to 0.8% CR and others.

These steels include steel 09G2, 09GS, 17GS, 10G2C1, 14G2, 15HSD, 10HNPP and many others. Steel in the form of sheets, varietal shaped rolled products are used in construction and mechanical engineering for welded structures, mainly without additional thermal processing. Low-alloyed low carbon steel welded well.

For the manufacture of pipes of large diameter, steel 17gs is used (0.2 \u003d 360 mb, B \u003d 520MP).

Reinforcement steel

For reinforced concrete structures, carbon or low-carbon steel is used in the form of a smooth or periodic rod profile.

Steel St5P2 - B \u003d 50MPa, 0.2 \u003d 300MPa, \u003d 19%.

Steel for cold stamping

To ensure high stamps, the ratio in / 0.2 steel should be 0.5-0.65 at at least 40%. The stamp was the worse than the carbon in it. Silicon, increasing the yield strength, reduces the stamp, especially the ability of steel to exhaust. Therefore, cold-rolled boiling steel 08kp, 08FCP (0.02-0.04% V) and 08U (0.02-0.07% AL) are more widely used for cold stamping.

Structural (machine-building) cemented (nitro-cement) Alloy steel

For the manufacture of parts, reduced cementation, low carbon (0.15-0.25% C) steel. The content of alloying elements in steels should not be too high, but should provide the required calcination of the surface layer and core.

Chromium steel 15x, 20x are designed for the manufacture of small products of simple shapes, cemented to depth 1.0-1.5mm. Chromium steel compared to carbonistic possess higher strength properties with some less plasticity in the core and better strength in the cementable layer., Sensitive to overheating, the calcination is small.

Steel 20x - B \u003d 800MP, 0.2 \u003d 650MPa, \u003d 11%, \u003d 40%.

Chromovanadium steel. The doping of chromium steel by vanadium (0.1-0.2%) improves mechanical properties (steel 20khf). In addition, chromovanadium has become less prone to overheating. Use only for the manufacture of relatively small parts.

Typical curriculum

Typical curriculum - This is a document designed to implement state requirements for the minimum content and level of training of graduation institutions of secondary special education. It defines a general list of disciplines, and mandatory amounts of time for their implementation, species and minimal duration of the practice, an exemplary list of educational sites, laboratories and workshops. The curriculum also provides for the course design of no more than three disciplines at the entire period of study. Types of production practices and their duration is determined in accordance with the model learning practice for a given specialty. The schedule of the educational process is a recommendatory nature and can be adjusted by the educational institution with the obligatory observance of the duration of theoretical training, examination sessions, as well as the timing of the summer holidays for the winter and taking academic year (see Table 1).

TABLE 1

Name educational process academic disciplines

Semester distribution

Number of control

Number of hours

Distribution of courses and semesters

Exams

Kurso-out project

Teo-Ret. sn.

Lab. Print classes

Materials Science and electrical materials

From the curriculum, it can be seen that on the subject of "Materials and Electradaratioster" of everything is given 60 hours. Of these, 44 are theoretical and 16- practical. The minimum number of tests is 2 works. There are laboratory classes. Course, exchange project, no credit. The subject "Materials and Electradiocratic" is studied by 2nd the year. In the 3-week of study 18 weeks, a week for 2 hours: 18 * 2 \u003d 36 hours are studying in the 3 semester. In the 4th semester of training 12 weeks, a week for 2 hours: 12 * 2 \u003d 24 hours learn for 4 semester. Total for 3 and 4 semester: 36 + 24 \u003d 60 hours, fully studying this item on 2 course.

Themed Plan

Themed Plan - It is part of the curriculum. Training program - This is a document in which the characteristic of the content of the material studied by year of study and sections (themes) is given. The thematic plan consists of sections that include topics. Thematic plan distributes hours by partitions from the total number of hours. As anathess on the subject of "Materials and Electradiodeter" in the "Conductive Materials" section, 12 hours are assigned.

TABLE 2

	Topic Name	Number of hours
			Theoretical classes
	Chapter 4. Conductive Materials
	High conduction materials
	Superconductors and cryopolids
	Conductivity conductors
	Test

Calendar-thematic plan

Calendar and thematic plan -the planning account, its goals is to determine the subject, the type of method and the equipment of lessons on the selected subject. Drawing up a calendar-thematic plan is the first step of creating a flowring systematization. The source document here is the curriculum. The calendar the thematic plan provides for interprecotement. According to the calendar-thematic plan, the curriculum is focused on the thematic plan in the preparation of the avenous plan. Calendar-thematic plan (see Table 3).

Development of lesson

Studying the curriculum, the teacher carefully analyzes each topic, which makes it possible to clearly determine the content of the training, establish interprecotement. Based on the curriculum, a calendar-thematic plan is drawn up and already on the basis of the calendar-thematic plan is drawn up an actual plan. When determining the purpose and content of the lesson arising from the curriculum, the content of the recording, skills and skills that students must learn at this lesson are determined. Analyzing previous lessons, and establishing the extent to which their tasks are solved, find out the cause of shortcomings, and on the basis of this determine what changes need to be made in this lesson. We have a lesson structure and time for each part of it, form the content and nature of educational work during the lesson.

Lesson plan

Thing: Materials Science and ElectradiOther materials Group 636

Subject:Classification and basic properties

a) learning: Introduce students with the concepts and basic properties of conductive materials, tell about their destination

b) developing: Develop interest in material science and electrical framework

c) Educational: Develop a need for self-education

Type of lesson: Combined

Method of presentation:search

Visual aids: Poster number 1, PC

Time:90 min.

During the classes

I.. Introductory:

Written survey for two options + 3 Uch-smi at the board (Appendix1)

II.. Main part:

1. Message of the target of the new topic

2. Statement of new material Time 40 min.

a) basic concepts

b) conductors classification

c) scope of application

3. Answers to questions of students Time 10 min.

4. Fastening a new material Time 20 min.

Written survey for 2 options + 3 Uch-Xia at the board (Appendix 2)

III. Final part:time 3 min.

1. Summing up

2. Task for the house: p. 440 Answers to questions, independently consider the topic number 2, 3, 4, 5

3. Final Teacher's Final

Teacher

Bibliography

1. Lakhtin Yu. M., Leontiev V. P. Materials Science. - M.: Mechanical Engineering, 1990

2. Technological processes of machine-building production. Edited by S. I. Bogodukhov, V. And Bondarenko. - Orenburg: OGU, 1996

application1

Written surveyon 2nd options

Option 1

1 . What studies the subject material science.

2. Types of metals.

3. Metal classification

4. Allhotropic transformation

5 . Properties of metals

Option 2.

1. Determination of metals hardness

2. Mechanical properties

3. Plastic

4. Endurance

5. Technological properties

Appendix 2.

Written survey

1 - option

1. Semiconductor materials

2. Supplements

3. CryOruders

4. Characteristics of semiconductor materials

5. Elasticity of materials

Option 2

1. Semiconductor materials.

2. Dielectric materials

3. Plasticity

4. Elasticity

5. Supplements

application3

Abstract lesson on the topic" Conductive materials"

The increase in the role of equipment and technical knowledge in the life of society is characterized by the dependence of science from scientific and technical developments, increasing technical equipment, creating new methods and approaches based on the technical method of solving problems in different areas of knowledge, including military-technical knowledge. A modern understanding of technical knowledge and technical activities is associated with the traditional circle of problems and with new directions in machinery and engineering, in particular with the technique of complex computing systems, problems of artificial intelligence, systemotechnics, etc.

The specifications of the concepts of technical knowledge is primarily due to the specifics of the subject of reflection of technical objects and technological processes. Comparison of technical knowledge objects with objects of other knowledge shows their specific community, propagating, in particular, to such features as the presence of structurality, systematic, organization, etc. Such common features are reflected by the general scientific concepts of the "Property", "Structure", "System", "Organization", etc. Of course, the general features of the objects of technical, military-technical, natural science and social and scientific knowledge are reflected by the philosophical categories of "matter", "Movement", "the reason", "consequence", etc. Non-scientific and philosophical concepts are also used in the military and technical sciences But do not express their specifics. At the same time, they help deeper, fully comprehend the content of the objects of technical, military-technical knowledge and reflecting their concepts of technical sciences.

In general, philosophical and general scientific concepts in technical sciences act as worldview and methodological means of analyzing and integrating scientific and technical knowledge.

The technical object is undoubtedly part of the objective reality, but the part is special. His emergence and existence are associated with the social form of motion of matter, human history. This determines the historical nature of the technical object. It features the production functions of society, it acts as an embodiment of people's knowledge.

The emergence of technology is a natural historical process, the result of human production activities.

Its initial moment is the "man's organs". Strengthening, addition and replacement of working bodies - social necessity implemented by using nature and incarnation in converted natural bodies of labor functions.

The formation of the technique proceeds in the process of making tools, fixtures of natural bodies to achieve the goal. And manual rubble, and a tree trunk that performs the function of the bridge, etc. - All these are means of enhancing an individual, increasing the effectiveness of its activities. The natural object that performs the technical function is already in the potency of the technical object. It recorded the feasibility of its device and the usefulness of constructive improvements due to the part-time of its parts.

Practical design of the design as integrity indicates the current existence of a technical object. Its essential properties are functional utility, unusual combination of materials, the subordination of the material properties of the ratio between the components of the system. Technical construction is a compound connection; This procedure provides as long as possible and efficient functioning of the gun, excluding its self-destruction. The design component is the part as the source and indivisible unit for it. And finally, with the help of technical design, the method of social activities reaches technological. The technology is the side of public practice, which is represented by the interaction of the technical means and the converted object, is determined by the laws of the material world and is regulated by technology.

Technical practice reveals itself in relation to a person to machinery as an object, to its parts and their connections.

Operation, manufacture and design are closely connected with each other and are a kind of technical practice. As an object of operation, the technique acts as some material and functional integrity, the preservation and regulation of which is an indispensable condition for its use. The moving contradiction of operation is the discrepancy between the conditions for the functioning of the technique and its functional features. Functional features involve the constancy of the conditions of operation, and the operating conditions tend to change.

Overcoming this contradiction is achieved in technology, in finding typical technological operations.

The internal contradiction of the technology is the discrepancy between the natural processes used and the needs for increasing its reliability and efficiency. Overcoming this contradiction is achieved in the design of more perfect techniques, with which you can use more fundamental patterns of nature. Technique is not passive towards technology, the tool affects the goal.

The new technique changes technology, the technology itself becomes a means of implementing the internal advantages of the designed technique.

In constructing with the greatest fullness, the social essence of the technical object is found. It synthesized a constructive structure in accordance with the production function specified by the society. The technique forms a condition for the development of society, its attitude towards nature is mediated, is a means of resolution of contradictions between man and nature. Technical object - carrier of industrial, technological functions of a person. Without technical progress it is impossible to achieve social homogeneity of society and the comprehensive development of each individual.

The properties of the technical object are detected in technical practice are fixed in knowledge of the techniques, manufacturing and improving equipment. Empirically found proportions between technical parts and the formation of "technical objects", relatively sustainable information about technical devices, about their essential components and properties. In the form of such objects, for example, descriptions of lifting transmission mechanisms, clocks, most important crafts and materials were formed.

Transition to machine technique, transmitting workers tools to mechanisms caused the design of technical devices in life, which demanded the theoretical development of the concept of "machine" and obtaining various idealization (kinematic pair, strength dynamics, construction).

The formation of concepts of technical science is influenced by the patterns disclosed during the study of natural sciences, in particular, theoretical mechanics. At the same time, it should be recognized that the concept of technical construction receives its expression within technical knowledge. Historically, it is formed as a system of provisions about the machine, a mechanical totality of parts and their natural relation, which ensures the obtaining effect.

The formation of technical disciplines occurred in various ways. Technical disciplines about engines are based on the results of natural science, on the knowledge of the laws of nature and the application of laws of physics for technology. Applied character is the technical kinematics, the dynamics of the machines and the doctrine of the details of the machines. These disciplines were formed on the basis of theoretical mechanics and descriptive geometry, which was expressed in the creation of a special language.

Technical sciences were formed not only by application of natural science to technology, but also by using centuries-old experience, his understanding and giving it a logically clear species. In this way, sciences of various types of machines, materials science, etc., proven in practice, the empirical data of these technical disciplines were maintained and included in general science about machines. And so far, many techniques for the manufacture and operation of the equipment did not receive a proper theoretical justification.

The formation of technical science laid an end to a handicraft relationship when certain mechanisms were improved in parts for decades and even centuries. Understanding that the machine is the transformation of movement in the form, the necessary production and in its essence consisting of kinematic pairs, has the basis for the scientific design of a variety of technical devices in the XIX century.

From what has been said, it is clear that technical science explores its object, although it is able to explain the functioning and handicrafts, manual labor instruments that were created without a scientific justification. The technical science object is formed in the process of allocating the essential and necessary properties of technology, the design of the machine. The machine, its components, the relationship between them, their composition, the natural base of the components and the technological process - all this object of technical science. The object of technical science is a source of scientific and technical knowledge. Its research gives, in particular, the structures and their elements. In the structure, stability, repeatability is fixed, necessity,

the pattern of composition elements of the machine. In relation to the structure, the component of the machine acts as an element. The mental production of the element of the structure is associated with distraction from the physical dimension and natural base of the component. Ultimately, all scientific and technical concepts are displayed technical object.

The concepts of "technical object" and "technical science object" perform various methodological function in the philosophical analysis of technology and scientific and technical knowledge. The concept of the objective world is fixed in the concept of "technical object". The technical object is displayed in philosophical, social, natural and technical sciences, and every time science is extinguished by the subject area peculiar to it. The concept of "technical science" is recorded by the subject of technical sciences, their attitude to objective reality. The main object of technical sciences is the car, as it is organized with its help and it is regulated. The machine facilitates and replaces human labor, serves as a means of achieving the goal.

In technical science, first of all, studies of the elements, their relations and technical structures are allocated. To form a subject of technical science, it is important to allocate, describe and explain the technical elements, their relationships and possible structures in which production functions useful for society are materialized. But this technical science does not end. It includes the rules for the synthesis of new technical structures, calculated methods and form of design.

Rules and design rules, graphical and analytical calculation methods bring technical science with technical creativity, design work. The subject of technical sciences is formed in direct dependence on creativity of technology. This is the specifics of technical sciences, which are a means of improving technology, rethinking natural science data, opening technological methods and inventions of technical structures.

As the most important factor in technical creativity, the rules involve the achievement of the strength and reliability of the technical means, the wear resistance and the heat resistance of its parts, etc. These rules form the framework of the design, excluding that it does not correspond to the technical science of the machine functioning. On the basis of rules and norms of engineering activity, methods for solving problems are being developed.

Principles act as prerequisites of activity as its organizing and guide. Thus, in the subject of technical sciences, not only the patterns of the technical object, but also the patterns of technical design, methods, rules, norms and principles of design of technology are included.

Methodology for the lesson.

I go to the office number 24, I greet students.

The introductory part of the lesson begins.

I.. Introductory:

1. Organizational moment: Report checking time 2 min.

Checking the presence of students on the report. On checking the presence of students in the lesson we assume 2 minutes. Then I make a survey of homework.

2. Checking homework: Time 15 min.

Interview

Survey I spend 10 questions in the form of questions. They include questions on the topic covered. At the test we take 15 minutes.

TEST

1 . What studies the subject Materials

2. Conductive materials

3. Semiconductor materials

4. Dielectric materials

5. Lucky

6. Compounds

7. Glue

8. Strength

9. Elasticity

10. Plasticity

Structural steel and alloys

Constructive are called steel, intended for the manufacture of machine parts (machine-building steel), structures and structures (construction steel).

Carbon structural steel carbon structural steel are divided into ordinary quality steel and high-quality.

Ordinary quality steel manufactures the following stamps of St0, ST1, ST2, ..., ST6 (with increasing the room increases the carbon content). ST4 - carbon 0.18-0.27%, manganese 0.4-0.7%.

Ordinary quality steel, especially boiling, cheapest. They began to be cast into large ingots, as a result of which they are developed in them and they contain a relatively large number of non-metallic inclusions.

With an increase in the conditional number of the brand of steel, the tensile strength (SV) and fluidity (S0.2) increases and the plasticity decreases (D, Y). ST3SP has SV \u003d 380490MPa, S0.2 \u003d 210250MP, D \u003d 2522%.

From steels of ordinary quality, hot-rolled ordinary rental is made: beams, chawllers, corners, rods, and sheets, pipes and forgings. Steel in the state of delivery are widely used in construction for welded, riveted and bolted structures.

With an increase in the content of carbon steel, the weldability deteriorates. Therefore, steel ST5 and ST6 with a higher carbon content are used for elements of building structures that are not subjected to welding.

High-quality carbonaceous steel is paid in compliance with more stringent conditions regarding the composition of the charge and melting and casting. S.<=0.04%, P<=0.0350.04%, а также меньшее содержание неметаллических включений.

High-quality carbon steel marked with numbers 08,10,15, ..., 85, which indicate the average carbon content in hundredths of percent.

Low carbon steel (with<0.25%) 05кп, 08,07кп, 10,10кп обладают высокой прочностью и высокой пластичностью. sв=330340МПа, s0.2=230280МПа, d=3331%.

Steel without heat treatment is used for low-loaded parts, responsible welded structures, as well as for parts of machines, strengthened cementation.

Medium carbon steel (0.3-0.5% c) 30.35, ..., 55 are used after normalization, improvement and surface hardening for a wide variety of parts in all industries. These steel compared to low carbons have higher strength at lower plasticity (SV \u003d 500600MP, S0.2 \u003d 300360MP, D \u003d 2116%). In this regard, they should be used for the manufacture of small parts or larger, but not requiring end-to-end calcination.

Steel with a high carbon content (0.6-0.85% C) 60.65, ..., 85 have high strength, wear resistance and elastic properties. From these steels, springs and springs, spindles, castle washers, rolling rolls, etc. are manufactured.

Alloy structural steel

Alloyed steel is widely used in tractor and agricultural engineering, in the automotive industry, heavy and transport engineering to a lesser extent in machine tool, instrumental and other types of industries. This began to be used for severely loaded metal structures.

Steel, in which the total amount of the content of alloying elements does not exceed 2.5%, refer to low-alloyed, containing 2.5-10% to doped, and more than 10% to high-alloyed (iron content of more than 45%).

The most widespread use in construction was low alloy steel, and in mechanical engineering - alloyed steel.

Alloyed structural steel marked with numbers and letters. The two-digit figures given at the beginning of the brand indicate the average carbon content in hundredths of the percent, the letter to the right of the numbers denote the doping element. Example, steel 12x2n4a contains 0.12% C, 2% CR, 4% Ni and refers to high-quality, on which indicates at the end of the brand of the letter ²².

Structural (machine-building) Improved alloyed steel steel have a high yield strength, low sensitivity to voltage concentrators, in products operating at a multiple load application, a high endurance limit and a sufficient stock of viscosity. In addition, improved steel have good calcination and low sensitivity to vacation fragility.

With complete calcination, the steel has the best mechanical properties, especially the resistance to fragile destruction - the low threshold of the coolant, the high value of the development of the CST crack and the viscosity of the destruction of K1c.

Chromium steel 30x, 38x, 40x and 50x are used for medium-wide details of small size. With an increase in carbon content, durability increases, but plasticity and viscosity are reduced. The calcination of chromium steels is small.

Steel 30x - SV \u003d 900MP, S0.2 \u003d 700MP, D \u003d 12%, Y \u003d 45%.

Chromearganese steel. A joint doping of chromium (0.9-1.2%) and manganese (0.9-1.2%) allows you to get steel with sufficiently high strength and calcination (40HG). However, chromanganese steel has a reduced viscosity, an increased threshold of the cooler (from 20 to -60 ° C), the tendency to the vacation fragility and the growth of the austenite grain during heating.

Steel 40HGTr - SV \u003d 1000MP, S0.2 \u003d 800MP, D \u003d 11%, Y \u003d 45%.

Chromocremarganese steel. High complex properties have chromocremmerganese steel (chromanxyl). Steel 20XGS, 25HGS and 30HGS have high strength and good weldability. Khromansyl steel is also used in the form of sheets and pipes for responsible welded structures (aircraft construction). Steel chromansyl is prone to reversible vacation fragility and decarburization when heated.

Steel 30xgs - SV \u003d 1100MP, S0.2 \u003d 850MP, D \u003d 10%, Y \u003d 45%. Chromonichel steels have high calcination, good strength and viscosity. They are used to manufacture large products of complex configuration, working with dynamic and vibratory loads.

Steel 40HN - SV \u003d 1000MP, S0.2 \u003d 800MP, D \u003d 11%, Y \u003d 45%.

Chromonicelmolibden steel. Chromonichel steels have a tendency to reversible brittleness, to eliminate which many details of small sizes from these steels are cooled after high vacation in oil, and larger parts in water to eliminate this defect steel are additionally doped with molybdenum (40xn2mA) or tungsten.

Steel 40HN2MA - SV \u003d 1100MP, S0.2 \u003d 950MP, D \u003d 12%, Y \u003d 50%.

Chromonicelmolibdenovadium steel has high strength, plasticity and viscosity and low chlorosity threshold. This contributes to the high nickel content. The disadvantages of steels are the difficulty of their treatment with cutting and a large tendency to form flocks. Steel is used to manufacture the most responsible parts of turbines and compressor machines.

Steel 38XN3MP - SV \u003d 1200MP, S0.2 \u003d 1100MP, D \u003d 12%, Y \u003d 50%.

Spring steel general purpose

Spring steel are designed for the manufacture of springs, elastic elements and spring springs. They must have high resistance to small plastic deformations, endurance limit and relaxation resistance with sufficient plasticity and viscosity.

For small cross sections, carbon steel 65.70,75,85 is used. Steel 85 - S0.2 \u003d 1100MP, SV \u003d 1150MP, D \u003d 8%, Y \u003d 30%.

More often for the manufacture of springs and springs use alloy steel.

Steel 60C2 chops and 65С2VA having high calcination, good strength and relaxation resistance are used for the manufacture of large high-loaded springs and springs. Steel 65С2VA - S0.2 \u003d 1700MP, SV \u003d 1900MPA, D \u003d 5%, Y \u003d 20%. When elastic elements operate under conditions of strong dynamic loads, steel with nickel 60s2H2a.

For the manufacture of automotive springs, steel 50khga is widely used, which, according to technical properties, surpasses silicon steel. For valve springs, steel 50khf is recommended, not prone to overheating and decarburization.

Ball bearing steel

For the manufacture of rolling bodies and bearing rings of small cross sections, high-carbon chromium chromium steel SHH15 (0.95-1.0% C and 1.3-1.65% CR) are usually used, and large sections - chromearganese steel SHH15SG (0.95-1.05% C, 0.9-1.2% CR, 0.4-0.65% Si and 1.3-1.65% Mn), calcining for greater depth. Steels have high hardness, wear resistance and contact fatigue resistance. There are high requirements for the content of non-metallic inclusions, as they cause premature fatigue destruction. Invalid also carbide inhomogeneity.

For the manufacture of rolling bearings operating at high dynamic loads, cementable steel 20x2H4A and 18HGT are used. After gas cementation, high vacation, hardening and vacation parts of the bearing of steel 20x2n4a have on the surface 58-62 HRC and in the core 35-45 HRC.

Wear-resistant steel

For details working on wear under abrasive friction and high pressure and impact conditions, high-headed carved austenitic steel 110g13l, containing 0.9-1.3% C and 11.5-14.5% Mn. It possesses the following mechanical properties: S0.2 \u003d 250350MP, SV \u003d 8001000MP, D \u003d 3545%, Y \u003d 4050%.

Steel 110g13l has high wear resistance only at shock loads. With low shock loads, in combination with abrasive wear, either with pure abrasive wear, the martensitic transformation does not flow and wear resistance of steel 110g13l low.

For the manufacture of hydroturbine and hydro-pumping blades, ship rowing screws and other parts operating under wear conditions at cavitation erosion, steel with unstable austenite 30x10g10.0x14Ag12 and 0x14g12m, experiencing partial martensitic transformation during operation.

Corrosive and heat-resistant steel and alloys

Heat resistant steel and alloys. The increase in the loan resistance is achieved by introducing into steel mainly chromium, as well as aluminum or silicon, i.e. Elements in solid solution and forming oxide (CR, FE) 2O3, (Al, Fe) 2O3, during heating process.

For the manufacture of various kinds of high-temperature installations, parts of furnaces and gas turbines are used by heat-resistant ferritic (12x17,15x25t, etc.) and austenitic (20x23n13,12x25n16g7ar, 36x18n25С2, etc.) steel,

possessing heat resistance. Steel 12x17 - SV \u003d 520MP, S0.2 \u003d 350MP, D \u003d 30%, Y \u003d 75%.

Corrosion-resistant steel is resistant to electrochemical corrosion.

Steel 12x13 and 20x13 are used for the manufacture of parts with increased plasticity exposed to shock loads (valves of hydraulic presses, household goods), as well as products experiencing the effect of weakly aggressive media (atmospheric precipitation, aqueous solutions of organic acid salts).

Steel 30x13 and 40x13 are used for carburetor needles, springs, surgical instruments, etc.

Steel 15x25t and 15x28 are used more often without heat treatment for the manufacture of welded parts operating in more aggressive environments and not exposed to shock loads, at no lower-20 ° C.

I go to the final part of the lesson in which we bring the results of the lesson. I highlight the main points of the topic, I emphasize the need for the ugument of this topic. I give a homework. We bring the results of the lesson. Issimate the estimates of active students to encourage their needs of self-education.

III. Final part:time 3 min.

1. Summing up

Once again, allocating the most important information on the topic "Classification and basic properties of conductive materials."

2. Task for the house: p. 94 Answer questions, Problem No. 3,4,6,8

3. Final word of the teacher: I say goodbye to students.

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Semiconductors

Semiconductors - a large class of substances whose specific resistance is changed over wide range from 10 -5 before 10 10 Ohm ∙ M..

Semiconductors have intermediate properties between metals and dielectrics. Characteristic for semiconductors is not the value of the resistance, and the fact that it is influenced by external conditions varies in wide limits.

Semiconductors include:

a) elements III, IV, V and VI groups of the periodic system of elements, for example SI, GE., As, SE, TE.;

b) alloys of some metals;

c) oxides (metal oxides);

d) sulphides (sulfur compounds);

e) selenides (connections with selenium).

The resistance of semiconductors depends on:

a) temperature;

b) illumination;

c) the presence of impurities.

The electrical resistance of semiconductors is reduced and when illuminated by their light.

1. Own conductivity of semiconductors.

Own conduction - Electrical conductivity of a chemically pure semiconductor.

In a typical semiconductor (silicon crystal SI) Atoms are united covalent (atomic) connection. At room temperature, the average energy of the thermal motion of atoms in the semiconductor crystal is 0.04 EV. This is significantly less than the energy required for the separation of the valence electron, for example, from a silicon atom ( 1.1 EV). However, due to the unevenness of the distribution of thermal motion energy or with external influences, some silicon atoms are ionized. Form free electrons and vacancies in a covalent bond - the so-called hole. Under the influence of the external electric field, an ordered movement of free electrons and an ordered movement in the opposite direction of the same number of holes are arising.

Electronic conductivity or conductivityn. -Type (from lat. negative - Negative) - the conductivity of semiconductors, due to electrons.

Hole conductivity or conductivityp. -Type (from lat. Positive is positive) - the conductivity of semiconductors caused by holes.

In this way, own conduction The semiconductor is due to the two types of conductivity simultaneously - electronic and meroral.

2. The impurity conductivity of semiconductors.

Adjustment - The electrical conductivity of semiconductors, due to the presence of impurities (impurities - atoms of extraneous elements).

The presence in the semiconductor impurities substantially changes its conductivity. For example, when administered to silicon about 0.001 at.% Bora, its conductivity increases by about 10 6 times.

Basically, the impurities atoms have valence, which differs in one from the valence of the main atoms.

Donor impurities - impurities with greater valence reporting semiconductor electronic conductivity.

Semiconductor (silicon) + donor (arsenic) \u003d semiconductor n.-Type.

Acceptor impurities - impurities with less valence communicating the semiconductor power conductivity.

Semiconductor (silicon) + acceptor (indium) \u003d semiconductor r-Type.

3. Semiconductor diodes and triodes. Their application.

The principle of action of most semiconductor devices is based on the use of properties p.- n.- Transformation.

Electronics (or p. - n. -transition) - the border of the contact of two semiconductors with various types of conductivity.

Through the border of the section, diffusion of electrons and holes that encountered recombine are occurred.

On the border of the section in the electronic semiconductor remains positive ions of the donor impurity, and negative ions of acceptors are formed in the hole. It is formed so-called locking (double electric layer), whose tension E. rEP Directed from the electronic semiconductor to the hole. Through this double layer can break through n.-Polpolnik B. p.-Polpolnik only such electrons that have quite large energies for this. The external electrical field applied to two heterogeneous semiconductors, depending on its direction, can and loosen the field of the locking layer.

The locking layer has one-sided conductivity: The locking layer passes the current in the direction opposite the field of the locking layer, and does not pass the current in the direction that coincides with the locking layer field.

Semiconductor diode - device with one p.- n.-There.

Volt-ampere characteristics - The dependence of the current I. From voltage U. attached to the diode.

Semiconductor triode (or transistor) - device with two p.- n.- Transfers.

Transistors (like lamp triodes) are used to enhance weak electrical signals.

Control questions

1. What substances are called semiconductors?

2. What is the difference between semiconductors from conductors and dielectrics?

3. From what depends the electrical conductivity of semiconductors?

4. What properties of semiconductors are used in thermo- and photoresistors?

5. What is the mechanism of its own conductivity of semiconductors?

6. How are free electrons and holes formed?

7. What is the mechanism of impurity conductivity of semiconductors?

8. What impurities are called donor, and what are the acceptor?

9. How to explain one-sided conductivity p.- n.- Transfer?

10. What is a volt-ampere characteristic p.- n.- Transfer? Explain the occurrence of direct and reverse current.

11. What direction in semiconductor diode is throughput for current?

12. What is semiconductor triode (or transistor)?

All physics lessons grade 11
Academic level

1st semester

ELECTRODYNAMICS

2. Electric current

Lesson 12/23

Subject. Semiconductor devices

The purpose of the lesson: clarify students the principle of operation of semiconductor devices.

Type of lesson: lesson studying a new material.

Lesson plan

Knowledge control		1. What is the determination of the electronic conductivity of the semiconductor? 2. What is the conditioned by the pelon conductivity of the semiconductor? 3. What impurities are called donor? acceptor? 4. What impurity need to enter to get a semiconductor N -typ? P -typ?
Demonstrations		Fragments of the movie "Electric Current in Semiconductors".
Studying a new material		1. Semiconductor diode. 2. How does the transistor work? 3. The use of semiconductors. 4. Integral chips.
Fixing the material studied		1. Qualitative questions. 2. Learning to solve problems.

Studying a new material

The semiconductor diode uses the one-sided conductivity of the P -N-transition. Such a diode has two contacts for connecting to the circle.

It is often said that in a slight resistance of the diode in the forward direction and very large resistance - in the opposite. However, this is not quite an accurate statement: in fact, for semiconductors in general and especially for electron-hole transitions, Oma is not performed. Therefore, any constant resistance in such conductors is not.

The volt-amps characteristic of the semiconductor diode has the form:

Semiconductor diodes are used to straighten the current of the variable direction (such a current is called variables), as well as for the manufacture of light diodes. Semiconductor rectifiers are highly reliable and have a considerable life.

Semiconductor diodes in radio devices are widely used: radio receivers, video recorders, TVs, computers.

Semiconductors in transistors are extremely important.

Transistors - semiconductor devices with two P - N-translates.

The main element of the transistor is a semiconductor crystal, for example, Germany, with donor and acceptor impurities entered into it. The impurities are distributed so that between semiconductors with the same impurity (they are called the emitter and the collector) there remains a thin layer of Germany with an admixture of a different type - this layer is called the base.

Transistors are two types: P -N -P -P -Transistors (Fig. A) and N -P -N -Transistors (Fig. B).

In the P -N -P -P transistor -Type in the emitter and the hole collector, there are significantly more than electrons, and in the database more electrons; In the transistor N -P -N -Type in the emitter and the electron manifold more than holes, and in the base more electrons.

Consider the operation of the transistor P - N - P -Type. Three output of the transistor from sections with various types of conductivity include in a circle as shown in the figure.

If the potential of the base P - n - p-transistor is higher than the emitter potential, the current does not flow through the transistor. Consequently, the transistor can work as an electronic key. If the base potential is lower than the emitter potential, even minor changes in the voltage between the emitter and the base lead to significant changes in the current strength in the collector's chain and, accordingly, to a voltage change on the resistor of significant resistance.

Having considered the operation of the transistor, we conclude that the electrical signals can be enhanced using the transistor.

Therefore, the transistor has become a major element of very many semiconductor devices.

The dependence of the electrical conductivity of semiconductors from temperature makes it possible to apply them in the thermalistors.

The thermistor is a semiconductor thermistor, the electrical resistance of which changes significantly when the temperature is raised.

Thermistors are used as thermometers to measure temperature.

In many semiconductors, the connection between electrons and atoms is so insignificant that it is enough to irradiate the light of the crystals so that they have an additional number of free charge carriers.

Photoresistors are used in signaling and automation systems, remote control of production processes, sorting products, etc.

Semiconductor diodes and transistors are "bricks" of very complex devices, are called integrated circuits.

Microcircuits work today in computers and TVs, mobile phones and artificial satellites, in cars, airplanes and even in washing machines.

The integrated circuit is made on a silicon plate. The size of the plate is from a millimeter to a centimeter, and on one such plate can be placed up to a million components - tiny diodes, transistors, resistors, etc.

Important advantages of integrated circuits are high speed and reliability, as well as low cost. It is precisely because of this on the basis of integrated circuits and managed to create complex, but many are available devices, computers and objects of modern household appliances.

Question to students during the presentation of a new material

First level

1. With what experience can be verified in one-sided conductivity of the semiconductor diode?

2. Why should the transistor base be very small?

3. What conduction can have the base of the transistor?

Second level

1. Why are the current in the collector approximately equal to the current in the emitter?

2. In the closed box placed a semiconductor diode and a row. The end of the devices are removed and attached to the terminals. How to determine which terminals belong to the diode?

Fixing the material studied

1. How will the increase in the thickness of its base affect the operation of the transistor?

2. It is known that in each transistor there are two P - N-transforms that are included towards each other. Is it possible to replace one transistor with two included in the same way diodes?

1. Increase the inclusion scheme of the transistor P - n - P to enhance the voltage.

2. Incline the inclusion scheme of the transistor N - P - n to enhance the voltage.

3. Why, to obtain the volt-ampere characteristics of the semiconductor diode, two different instrument connection schemes are used (see Fig. A, B)?

Solutions. In this case, the resistance of the ammeter is impossible to be infinitely small, and the voltmeter resistance is infinitely large. The diagram and cannot be used to measure the back current through the diode (almost all the current go through a voltmeter). The diagram cannot be used to measure the direct current voltage (the voltage to the ammeter is much higher than the voltage on the diode).

What we learned in class

The transistor is an electronic device from a semiconductor material, usually with three outputs, which allows you to control with a weak input signal with an electric current in an electrical circuit.

Using the transistor, you can enhance electrical signals.

The thermistor is a semiconductor thermistor, the electrical resistance of which is significantly changed in the case of temperature increase.

The semiconductor device in which the conductor property is used to change its resistance when illumination, is called a photoresistor.

Homework

1. Podre-1: § 16 (paragraph 5, 6, 7, 8); Podre-2: § 8.

РІВ1 № 6.6; 6.9; 6.15.

РІВ2 № 6.16; 6.17; 6.18.

РІВ3 №6.28; 6.2; 6.30.

Physics lesson grade 11

Theme lesson:

"Semiconductors.

Own and impurity conductivity of semiconductors. Electric current in semiconductors »

The purpose of the lesson

• To form students the concept of electric current in semiconductors, about the methods of measuring their properties under the action of temperature, illumination, impurities.
• Contribute to the expansion of the polytechnic outlook, motivate to study the subject, improve the ability to perceive and analyze technical, scientific information.
• The development of communicative competencies of students, their ability to work in the team.

Materials and equipment:

Computer, projector, electronic materials on the topic: "Semiconductors"; Cards - tasks for independent work in small groups; Set of semiconductor devices NPP - 2; demonstration galvanometer; DC source (4B); Demonstration switch; Electric lamp 60-100W on a stand; electric soldering iron; Connecting wires.

Lesson plan:

1. Repetition of the studied and actualization of the lesson theme.
2. Explanation of the topic of the topic.
3. Independent work of students in groups.
4. Summing up, job task.

1. Repetition of studied and actualization of the lesson theme (6min).

We must remember:

1. What is electric current?
2. What are taken for the direction of the current?
3. What kind of particles is formed by electric current in metal conductors?
4. Why in dielectrics can not occur electric current?
5. What do you think: is there any substances in nature that by the ability to carry out an electric current occupy an intermediate position?

Yes, it is semiconductors. A little more than half a century ago, they did not have a noticeable practical value. In electrical engineering and radio engineering, they were exclusively conducted by conductors and dielectrics. But the situation has changed dramatically when theoretically, and then almost an opportunity to control the electrical conductivity of semiconductors was practically opened.

What the main difference between the semiconductors from the conductors and what features of their structure have allowed to widely use semiconductor devices in almost all electronic devices, allowing to significantly increase their reliability, to significantly reduce the dimensions, and create new ones, which had only had to dream: Create cell phones, miniature Computers, etc.?

1. Explanation of the theme materials (15min)

1. Definition of semiconductors

A large class of substances whose resistivity is greater than that of the conductors, but less than the dielectrics and with increasing temperature decreases very sharply.

These include elements of the Mendeleev table: Germany, silicon, selenium, tellurium, india, arsenic, phosphorus, boron, etc. Some connections: Sulfur Sulfur, Sulfur Cadmium, Stinking Copper, etc.

1. The structure of semiconductors.

1. The atomic structure of the crystal solid silicon (projection on the screen);
2. Violation of parenoelectronic ties under the influence of external factors: an increase in temperature, illumination.

Demonstration of the dependence of the electrical conductivity of semiconductors:

RT 10K FS - K1

1. Electronic conductivity of pure semiconductor (projection)
2. Hole conductivity (projection)

There is a need to emphasize that the holes are not real particles. In both types of conductivity of semiconductors, only valence electrons are moving. The conductivity differs from each other only by the mechanism of electron movement. Electronic conductivity is due to the direction of movement of free electrons, and the hole is caused by the movement of the associated electrons moving from the atom to the atom, alternately replacing each other in the bundles, which is equivalent to the movement of holes in the opposite direction.

Thus, in semiconductors, two types of carriers are electrons and holes, the concentrations of which in pure semiconductors are the same - its own conductivity, it is small.

1. Impurity conductivity (projection)

The conductivity of semiconductors differs significantly from the presence of impurities in their crystals:

1. donor impurities - five-flow elements, easily sending electrons (AS, P) provide a quantitative advantage of electrons above the holes, creating N-type conductivity;
2. acceptor impurities are trailing elements (in, b) taking free electrons, forming holes. Created a p - type conductivity.

Demonstration of impurities and conductivity N - type and p - type:

n - type P - type

Of particular interest is the flow of current is not separate in semiconductors N - type or p - type, but through the contact of two semiconductors with different types of conductivity.

1. Independent work of students in groups (20min)

It is proposed on a voluntary basis to form groups of 4 students (this must be done before the lesson began to avoid chaotic movements across the office and time loss).

Each group is given a task that must be executed. It contains issues, qualitative tasks of different levels, calculated on both written and oral responses.

1. Summarizing

I heard answers to representatives of groups on the main questions of this topic, correct possible errors. We collect written reports. Estimates for work I exhibit after studying the second part of the topic and performing tasks for repetition, taking into account the CTU of each student in the group.

Task for the house: § 113; §114 textbook.

Explains features.

Semiconductors - substances capable of carrying out an electric current and to prevent its passage. This is a large group of substances used in radio engineering (Germany, silicon, selenium, as well as all sorts of alloys and chemical compounds of copper oxide). Almost all substances around us are semiconductors. The most common semiconductor It is silicon, constituting by approximate estimates of almost 30% of the earth's crust. For the manufacture of semiconductor devices, only silicon and germanium are mainly used. (Find them in Table D. I. Mendeleev - Appendix 2). What valence they have (in Table D. I. Mendeleev, find the column number in which they are located)?

In terms of its electrical properties, semiconductors occupy the middle place between the conductors and non-conductive electrical current. Write down in the notebook definition what is a semiconductor.

Consider the following three experiences (demonstration or posters)

First experience: Heating semiconductor

See what happens when the temperature is increasing? Resistance will decrease with increasing temperature?

What conclusion can be done?

The electrical conductivity of semiconductors is highly dependent on the ambient temperature. At a very low temperature, close to absolute zero (-273), semiconductors do not conduct an electric current, and with an increase in temperature, their resistance is reduced. On the basis of this, thermoelectric devices were created.

Thermistors.In semiconductors, electrical resistance is very dependent on temperature. This property is used to measure the temperature of the current in the chain with a semiconductor. Such devices are called thermistors or thermistors.

Thermistors are one of the simplest semiconductor devices. Release thermistors in the form of rods, tubes, discs, washers and beads in size from several micrometers to several centimeters.

The range of measured temperatures of most thermistors lies in the range from 170 to 570 K. But there are thermistors for measuring both very high (approximately 1300 K) and very low (approximately 4 - 80 k) temperatures. Thermistors are used to remote measurement of temperature, fire alarm, etc.

Second experience: Lighting with semiconductor light

See what happens when the illumination is increasing?

What conclusion can be done?

If the semiconductor is hosted, its electrical conductivity begins to increase. Using this property of semiconductors, photovoltaic devices were created. Also semiconductors are capable of converting light energy into electric current, such as solar panels.

Photoresistors.The electrical conductivity of semiconductors is worse not only when heated, but also when lighting.

It can be noted that when lighting a semiconductor, the current strength in the chain increases significantly. This indicates an increase in the conductivity (reduction of resistance) of semiconductors under the action of light. This effect is not associated with heating, as it can be observed at a constant temperature.

Electrical conductivity increases due to the rupture of bonds and the formation of free electrons and holes due to the energy of light falling on the semiconductor. This phenomenon is called a photoelectric effect.

The devices in which the photovoltaic effect in semiconductors use are called photoresistors or photoresistance. Miniaturity and high sensitivity of photoresistors make it possible to use them in a wide variety of science and technology for registration and measurement of weak light flows. Using photoresistors, the quality of surfaces determine the size of the products, etc.

Third experience: Adding an impurity to the semiconductor

See what happens?

What conclusion can be done?

When administered to the semiconductor impurities of certain substances, their electrical conductivity increases sharply.

We write in a notebookproperties of semiconductors

The electrical conductivity increases with increasing temperature (thermistor)

Electricity rises when lighting (photoresistor, solar panels)

The electrical conductivity increases when some impurities are introduced into the semiconductor. (semi-voltage diode)

The properties of semiconductors depend on their inner structure.Consider silicon - a four-dimensional element (show a three-dimensional model) that is, in the outer shell of the atom there are four electrons, weakly associated with the nucleus. The number of the nearest neighbors of each silicon atom also equals four.

The interaction of a pair of neighboring atoms is carried out with the help of a parenoelectronic connection, called covalent bond. In the formation of this connection from each atom, one valenny electron is involved. Atoms are located as close to each other that their valence electrons form uniform orbits passing around neighboring atoms, thereby binding atoms into a single substance.

Draw a resulting image in a notebook. (Drawing on the board)Students perform the same drawing in the notebook. Add more adjacent atoms.

When silicon heated, the kinetic energy of particles increases, and comes the rupture of individual connections. Some electrons become free and move between lattice nodes, forming an electric current. The conductivity of semiconductors caused by their free electrons is called electronic conductivity. When breaking the connection, a vacant place is formed with the missing electron - hole.

At low communication temperatures do not burst, therefore silicon at low temperatures does not conduct an electric current.

The conductivity of pure semiconductors, without impurities (own conductivity), is carried out by moving free electrons (electron conductivity) and the movement of associated electrons per vacant places of parenoelectronic bonds (hole conductivity). The conductivity of semiconductors is extremely strongly dependent on impurities. It was this dependence that the semiconductors made them in what they became in modern technique. There are donor and acceptor impurities. If there is a donor impurity in a semiconductor, if you add arsenic in silicon, an excess of electrons is observed, the semiconductor is calledn. -Type, in the presence of acceptor impurities, if adding indium in silicon, excess holes are observed, the semiconductor is called P-type.