Lesson "Semiconductors. Semiconductor devices". Approximate outline of the first lesson Lesson plan on the topic of semiconductor materials

Labor training lesson outline plan.

Class 9

Topic of section: Electrical engineering and electronics fundamentals. (3 hours)
Lesson topic number 27: Semiconductor devices.

Purpose: Introduce semiconductor devices.

During the classes:
1. Organizational part 3 min.
a) Greetings.
b) Identification of the absent.
c) Repetition of the passed material.
d) Announcement of the topic of the lesson. Recording the topic of the lesson in notebooks.
e) Communicating the goals and lesson plan to students.

2. Repetition of the passed material -7 min.

What are the main types of electrical work?

What are conductive materials?

Application of conductive materials?

3. Learning new material 10 min.

Semiconductor devices devices are called, the action of which is based on the use of the properties of semiconductor materials

Semiconductor devices include :

-Integrated circuits (microcircuits)

Semiconductor diodes (including varicaps, zener diodes, Schottky diodes),

Thyristors, photothyristors,

Transistors,

Charge coupled devices,

Semiconductor microwave devices (Gunn diodes, avalanche-transit diodes),

Optoelectronic devices (photoresistors, photodiodes, solar cells, nuclear radiation detectors, LEDs, semiconductor lasers, electroluminescent emitters),

Thermistors, Hall sensors.

The main Materials for the production of semiconductor devices are silicon (Si), silicon carbide (SiC), gallium and indium compounds.

Electrical conductivity semiconductors depends on the presence of impurities and external energy influences (temperature, radiation, pressure, etc.). The flow of current is caused by two types of charge carriers - electrons and holes. Depending on the chemical composition, a distinction is made between pure and impurity semiconductors.

Semiconductors

4.Practical work 18 min.
One way to do this is to measure the resistance between the emitter and collector leads with an ohmmeter when connecting the base to the collector and when connecting the base to the emitter. This disconnects the collector power supply from the circuit. With a working transistor, in the first case, the ohmmeter will show low resistance, in the second - on the order of several hundred thousand or tens of thousands of ohms.

Semiconductor diode - a semiconductor device with one electrical junction and two leads (electrodes). Unlike other types of diodes, the principle of operation of a semiconductor diode is based on the p-n-junction phenomenon.

Semiconductor diode testing

When testing diodes with AMM, the lower limits should be used. When checking a working diode, the resistance in the forward direction will be several hundred ohms, in the opposite direction - infinitely high resistance. In the event of a diode malfunction, the AMM will show in both directions a resistance close to 0 or a rupture during diode breakdown. The resistance of junctions in the forward and reverse directions for germanium and silicon diodes is different.

5. Lesson summary 2 min.
6. Cleaning of workplaces 5 min.

Physical properties of semiconductors Semiconductors are materials that, in terms of their conductivity, occupy an intermediate place between conductors and dielectrics. The main property of these materials is the increase in electrical conductivity with increasing temperature. They conduct electric current well These include metals, electrolytes, plasma ... The most used conductors are Au, Ag, Cu, Al, Fe ... They conduct electric current well These include metals, electrolytes, plasma ... The most used conductors are Au, Ag, Cu, Al, Fe ... Virtually do not conduct electric current These include plastics, rubber, glass, porcelain, dry wood, paper ... Virtually do not conduct electric current These include plastics, rubber, glass, porcelain, dry wood, paper ... Occupy intermediate conductivity position between conductors and dielectrics Si, Ge, Se, In, As Occupy an intermediate position in conductivity between conductors and dielectrics Si, Ge, Se, In, As

Physical properties of semiconductors R (Ohm) t (0 C) R0R0 metal semiconductor The conductivity of semiconductors depends on temperature. Unlike conductors, whose resistance increases with increasing temperature, the resistance of semiconductors decreases when heated. Near absolute zero, semiconductors have the properties of dielectrics.

Electric current in semiconductors Semiconductors are substances whose resistivity decreases with increasing temperature. Semiconductors include silicon, germanium, selenium, etc. The bond between atoms is electron pair, or covalent At low temperatures, bonds do not break

Intrinsic conductivity of semiconductors Under normal conditions (low temperatures) there are no free charged particles in semiconductors, so the semiconductor does not conduct electric current. Si

"Hole" When heated, the kinetic energy of electrons increases and the fastest of them leave their orbit. During the breaking of the bond between the electron and the nucleus, a free space appears in the electron shell of the atom. At this point, a conditional positive charge is formed, called a "hole". Si hole + + free electron

Impurity conductivity of semiconductors Dosed introduction of impurities into a pure conductor makes it possible to purposefully change its conductivity. Therefore, to increase conductivity, impurities are introduced into pure semiconductors, which are donor and acceptor Impurities Acceptor Donor p-type semiconductors P-type semiconductors n-type semiconductors n-type semiconductors

Hole semiconductors (p-type) In + Si The term "p-type" comes from the word "positive", which means the positive charge of the main carriers. This type of semiconductor, in addition to the impurity base, is characterized by the p-type conductivity. A small number of atoms of a trivalent element (for example, indium) are added to a tetravalent semiconductor (for example, silicon). Each impurity atom forms a covalent bond with three neighboring silicon atoms. To establish a bond with the fourth silicon atom, the indium atom does not have a valence electron, so it captures a valence electron from the covalent bond between neighboring silicon atoms and becomes a negatively charged ion, as a result of which a hole is formed. The impurities that are added in this case are called acceptor impurities.

Electronic semiconductors (n-type) As Si The term "n-type" comes from the word "negative", which means the negative charge of the main carriers. This type of semiconductor has an impurity nature. An impurity of a pentavalent semiconductor (for example, arsenic) is added to a tetravalent semiconductor (for example, silicon). In the course of interaction, each impurity atom enters into a covalent bond with silicon atoms. However, for the fifth electron of the arsenic atom, there is no place in the saturated valence bonds, and it goes over to the far electron shell. There, less energy is needed to detach an electron from an atom. The electron breaks off and becomes free. In this case, charge transfer is carried out by an electron, not a hole, that is, this type of semiconductor conducts electric current like metals. Impurities that are added to semiconductors, as a result of which they are converted into n-type semiconductors, are called donor.

Donor impurities are impurities that donate an extra valence electron. Semiconductors with donor impurities have electronic conductivity and are called n-type semiconductors. Acceptor impurities are impurities that lack electrons to form a complete covalent bond with neighboring atoms. Semiconductors with acceptor impurities have hole conductivity and are called p-type semiconductors.

Intrinsic conductivity of semiconductors A valence electron of a neighboring atom, being attracted to a hole, can jump into it (recombine). In this case, a new "hole" is formed in its former place, which can then similarly move along the crystal.

Intrinsic conductivity of semiconductors If the strength of the electric field in the sample is zero, then the movement of the released electrons and "holes" is random and therefore does not create an electric current. Under the influence of an electric field, electrons and holes begin an ordered (counter) motion, forming an electric current. The conductivity under these conditions is called the intrinsic conductivity of semiconductors. In this case, the movement of electrons creates electronic conduction, and the movement of holes creates hole conduction.

Diode A semiconductor diode is a semiconductor device with one electrical junction and two leads (electrodes). Unlike other types of diodes, the principle of operation of a semiconductor diode is based on the p-n-junction phenomenon. The diode was first invented by John Flemming in 1904.

Types and applications of diodes Diodes are used in: converting alternating current into permanent detection of electrical signals protection of various devices from incorrect polarity switching switching of high-frequency signals stabilizing current and voltage transmission and reception of signals Transistor An electronic device made of semiconductor material, usually with three terminals, allowing input signals to be controlled current in an electrical circuit. Typically used to amplify, generate and convert electrical signals. In 1947, William Shockley, John Bardeen and Walter Brattain first created a working bipolar transistor at Bell Labs.

Shpak S.I. physics teacher, KGB POU "KMT", Vladivostok

LESSON PLAN

Lesson number 39-40

Section: Electric current in various environments.

Lesson topic: Electric current in semiconductors. Semiconductor devices.

Purpose:

Give the concept of electron - hole conductivity of semiconductors. Explain the types of conduction. Consider the device and principle of operation of semiconductor devices and their application.

Develop a polytechnic outlook.

Cultivate interest in the subject.

Equipment:

Notebook;

Interactive board;

CRC for the publishing house "Electric current in metals" in the programMacromediaFlash;

CRC for publishing house "Semiconductors" in the programMacromediaFlash;

Handout: periodic table;

Mini-stand "Semiconductor devices".

Literature:

Myakishev G.Ya., Bukhovtsev BB, "Physics 10" Moscow, "Education", 2010.

Shakhmaev M.N., Shakhmaev S.M. "Physics 10" Moscow, "Education", 2007

Additional material "Semiconductor devices: device, principle of operation, application."

During the classes:

I Organizational part

II Reiteration

Questions for repeating the topic "Electric current in metals":

What are the main charge carriers in metals. What is the conductivity of metals.

To tell and demonstrate at ID the experiments confirming the existence of free electrons in metals (CRC for ID "Electric current in metals").

Solve the problem of calculating the dependence of metal resistance on temperature (in the field):

Aluminum wire at 0 0 C has a resistance of 4.25 ohms. What is its resistance at 20 0 C? (Answer: 12.29 ohm)

III ... New material:

1. Semiconductors.

Work in a notebook:

Definition: Semiconductors are substances whose resistivity depends on:

From temperature

From the presence of impurities,

From changes in illumination.

2. The mechanism of semiconductor conduction

Slide "Semiconductors":

In the normal state, electron bonds in semiconductors are strong and, therefore, there are no free charge carriers. As the temperature rises, the electron bonds are broken, and the electrons become free, therefore, the resistance decreases and the semiconductor conducts current. Likewise when changing illumination.

3. Semiconductor substances.

Slide "Semiconductor elements"

Assignment to students : Write down all semiconductor substances in a notebook using the periodic table. We check for ID.

4. Conductivity of semiconductors:

Work in a notebook:

The main charge carriers in semiconductors areelectrons and holes ... Electrons are negative, holes are positive.

Definition: The hole is where the electron left.

Therefore, the conductivity of semiconductorselectronic and hole .

Definition: Donor impurity - an excess of electrons, easily donates electrons. The main charge carriers are electrons. (n - a type).

Definition: Acceptor impurity - lack of electrons, easily accepts electrons. Major charge carriers - holes (p - type)

We fix the material by drawing up a diagram: Slide "Types of conduction"

5. Electric current through contact p – n type.

Slide p- n transition: Demonstration, teacher's explanation

n – p contact - direct transition,

p – n contact - reverse transition.

6. Semiconductor devices:

Working with the tutorial:

The task: study the device and principle of operation of semiconductor devices. Make a description of the device according to the plan.

(Device description plan: name; device; principle of operation; application).

Tell about the device and the principle of operation of the device. Demonstrate the operation of the device on the ID.

Semiconductor diode.

Slide "Semiconductor diode"

Device :

In a germanium crystal (n- type) enter an acceptor impurity of indium (p - type)

Operating principle :

Due to the diffusion of indium atoms deep into the germanium single crystal, a region with p-type conductivity arises at the germanium surface. The rest of the germanium sample, into which the indium atoms did not penetrate, still has conductivityn - type. Between two regions with conductivities of different types, p appears -n transition.

Application:

For rectifying electric current in radio circuits and computers.

Benefits:

Small size, energy saving, reliable, durable.

Disadvantages:

Sensitivity to temperature changes.

Thermistor.

Slide "Thermistor"

In semiconductors, resistance is temperature dependent, therefore, thermistors are used to measure temperature by current.

Benefits:

Small size, any shape, temperature variation from 170K to 570K.

Application:

Remote temperature measurement, Fire alarm.

Photoresistor.

Slide "Photoresistor"

The resistance of semiconductors depends not only on temperature. But also from the light. With increasing illumination, the current increases as the resistance decreases. Used to register weak light fluxes.

Benefits:

Miniature, high sensitivity.

Application:

Determination of the quality of surface treatment and control over the dimensions of products.

7. Homework:

Summarize the material using a table

Semiconductor devices:

Semiconductor device

Operating principle

Application

Lesson topic: "Semiconductor devices. Diodes"

The purpose and objectives of the lesson:

Educational:

the formation of an initial concept of the purpose, action and basic property of semiconductor diodes.

Educational:

to form a culture of mental work, the development of personality traits - perseverance, purposefulness, creative activity, independence.

Developing:

training in the use of the property of one-way conductivity.

Material and technical equipment of the lesson:

workbooks, teacher's computer, interactive whiteboard, presentation on the topic

Course of the lesson:

1. Organizational moment:

(Task: creating a favorable psychological mood and activation of attention).

2. Preparation for repetition and generalization of the passed material

What is electric current.

Current strength, units.

p – n transition.

Semiconductors.

Communication of the topic and purpose of the lesson.

Semiconductors. Diodes.

Explanation of perspective.

To study modern electronics, one must first of all know the principles of the device and the physical foundations of the operation of semiconductor devices, their characteristics and parameters, as well as the most important properties that determine the possibility of their use in electronic equipment.

The use of semiconductor devices gives huge savings in the consumption of electrical energy of power supplies and allows many times to reduce the size and weight of the equipment. The minimum power for supplying a vacuum tube is 0.1 W, and for a transistor it can be 1 μW, i.e. 100,000 times less.

3. The main stage.

New material

All naturally occurring substances are divided into three groups according to their electrical conductive properties:

Conductors,

insulators (dielectrics),

semiconductors

Semiconductors include many more substances than conductors and insulators. In the manufacture of radio devices, the most widespread are 4-valent germanium Ge and silicon Si.

The electric current of semiconductors is caused by the movement of free electrons and the so-called "holes".

Free electrons leaving their atoms create n-conductivity (n is the first letter of the Latin word negativus - negative). Holes create p - conductivity in a semiconductor (p - the first letter of the Latin word positivus - positive).

In a pure conductor, the number of free electrons and holes is the same.

By adding impurities, you can get a semiconductor with a predominance of electron or hole conductivity.

The most important property of p- and n-semiconductors is one-sided conductivity at the junction. This spike is called a p-n junction.

Add 5-valent arsenic (antimony) to a 4-valent germanium (silicon) crystal, then we get n - a conductor.

When adding 3-valent indium, we get p - conductor.

When the plus of the source is connected to the p-region, the junction is said to be on in the forward direction, and when the minus of the current source is connected to the p-region, the junction is said to be on in the opposite direction.

One-sided conductivity of the p and n junction is the basis of the action of semiconductor diodes, transistors, etc.

Having an idea of \u200b\u200bthe semiconductor, now let's start studying the diode.

The prefix "di" means two, indicating two adjacent zones of different conductivity.

Bicycle tire valve (nipple). Air can pass through it only in one direction - into the chamber. But there is also an electric valve. This is a diode - a semiconductor piece with two wire leads at both ends.

By design, semiconductor diodes can be planar or point.

Plane diodes have a large electron-hole junction area and are used in circuits in which large currents flow.

Point diodes are characterized by a small area of \u200b\u200bthe electron-hole junction and are used in circuits with low currents.

Conventional graphic designation of the diode. The triangle corresponds to the p-region and is called the anode, and the straight line, called the cathode, represents the n-region.

Depending on the purpose of the diode, its UGO may have additional symbols.

The main parameters by which diodes are characterized.

Forward current of the diode.

Reverse diode current.

Securing the material.

Reversing the polarity of the power supply connection in a circuit containing a semiconductor diode.

We connect in series a 3336L battery and an MH3.5 - 0.28 incandescent light bulb (for a voltage of 3.5V and a filament current of 0.28A) and connect this circuit to a floating diode from the D7 or D226 series so that a positive is supplied to the anode of the diode directly or through the light bulb, and cathode - negative battery voltage (Fig. 3, Fig. 4). The light should be on full glow. Then we change the polarity of the connection of the “battery - light bulb” circuit to the opposite (Fig. 3, Fig. 4). If the diode is good, the light is off. In this experiment, an incandescent light bulb performs a double function: it serves as an indicator of the current in the circuit and limits the current in this circuit to 0.28A, thereby protecting the diode from overload. In series with a battery and an incandescent lamp, you can turn on another milliammeter for a current of 300 ... 500mA, which would record the forward and reverse current through the diode.

4.Control moment:

Draw a diagram of an electrical circuit consisting of a direct current source, a micromotor, 2 diodes, so that using the switches to change the direction of rotation of the micromotor rotor.

Determine the poles of the flashlight battery with a semiconductor diode.

Study the conductivity of the diode yourself on the demo stand. Study of one-sided conductivity of a diode.

5.Final point:

assessment of success in achieving the objectives of the lesson (how they worked, what they learned or learned)

6. Reflective moment:

determination of the effectiveness and usefulness of the lesson through the pupils' self-assessment.

7. Information moment:

determining the prospects for the next lesson .

8. Homework

To consolidate the material covered, think about the following tasks and give their solution:

How to protect radio equipment from polarity reversal using a semiconductor diode?

There is an electrical circuit, which includes four series-connected elements - two light bulbs a and b and two switches A and B. In this case, each switch lights only one, only “its own” light bulb. In order to light both bulbs, both switches must be closed simultaneously.

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EXPLANATORY NOTE

To term paper

Organization and methodology of industrial training in the subject: Materials science and electro-radio materials

On the topic: Semiconductor materials

Introduction

I . Metals and alloys, as well as electrical materials are widely used in modern technology. Modern electronic instrument making has reached such a stage of development when important parameters of devices depend not so much on circuit solutions as on the used electro-radio materials and the perfection of technological processes for their manufacture. The material science subject consists of five sections. The first section is called general information about metals and alloys.

Metal is solid.

An alloy is a combination of 2 or more chemical elements

The component is the substances that make up the alloy.

II. Conductive materials are materials that have low resistivity.

III. Dielectric materials

Dielectrics are insulating materials.

IV. Semiconductor materials are materials that consume a small amount of energy during operation.

V. Magnetic materials - with attractive properties.

Structural steels and alloys

Structural steels are those intended for the manufacture of machine parts (machine-building steels), structures and structures (building steels).

Carbon structural steels

Carbon structural steels are classified into ordinary quality and high quality steels.

Steel ordinary qualities are produced in the following grades St0, St1, St2, ..., St6 (with an increase in the number, the carbon content increases). St4 - carbon 0.18-0.27%, manganese 0.4-0.7%.

With an increase in the conditional number of the steel grade, the ultimate strength (c) and yield strength (0.2) increase and the plasticity (,) decreases. St3sp has h \u003d 380490MPa, 0.2 \u003d 210250MPa, \u003d 2522%.

High quality carbon steels are smelted under more stringent conditions regarding the composition of the charge and the conduct of smelting and casting. Content S<=0.04%, P<=0.0350.04%, а также меньшее содержание неметаллических включений.

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

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

Medium carbon steels (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 steels, in comparison with low-carbon steels, have higher strength at lower plasticity (h \u003d 500600MPa, 0.2 \u003d 300360MPa, \u003d 2116%). In this regard, they should be used for the manufacture of small parts or larger ones that do not require through hardenability.

High carbon steels (0.6-0.85% C) 60, 65, ..., 85 have high strength, wear resistance and elastic properties. Springs and springs, spindles, lock washers, rolling rolls, etc. are made from these steels.

Alloy structural steels

Steels in which the total amount of alloying elements does not exceed 2.5% are classified as low-alloyed, containing 2.5-10% as alloyed, and more than 10% as high-alloyed (iron content is more than 45%).

Low-alloy steels are most widely used in construction, and alloyed steels in mechanical engineering.

Construction low-alloy steels

Low alloyed steels are called steels containing no more than 0.22% C and a relatively small amount of non-deficient alloying elements: up to 1.8% Mn, up to 1.2% Si, up to 0.8% Cr, and others.

These steels include 09G2, 09GS, 17GS, 10G2S1, 14G2, 15KHSND, 10KhNDP and many others. Steel in the form of sheets, sectional shapes are used in construction and mechanical engineering for welded structures, mainly without additional heat treatment. Low alloy, low carbon steels weld well.

For the manufacture of pipes of large diameter, 17GS steel is used (0.2 \u003d 360MPa, w \u003d 520MPa).

Reinforcing steels

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

Steel St5sp2 - w \u003d 50MPa, 0.2 \u003d 300MPa, \u003d 19%.

Steel for cold forming

To ensure high formability, the w / 0.2 ratio of steel should be 0.5-0.65 at not less than 40%. The more carbon it contains, the worse the stamping properties of steel. Silicon, increasing the yield stress, reduces the formability, especially the drawability of steel. Therefore, cold-rolled boiling steels 08kp, 08Fkp (0.02-0.04% V) and 08Yu (0.02-0.07% Al) are more widely used for cold forming.

Structural (machine-building) case-hardened (nitrocarburized) alloy steels

For the manufacture of parts hardened by carburizing, low-carbon (0.15-0.25% C) steels are used. The content of alloying elements in steels should not be too high, but should provide the required hardenability of the surface layer and core.

Chromium steels 15X, 20X are intended for the manufacture of small products of simple shape, cemented to a depth of 1.0-1.5mm. Chromium steels, in comparison with carbon steels, have higher strength properties with some lower ductility in the core and better strength in the case-hardened layer, sensitive to overheating, and low hardenability.

Steel 20Kh - w \u003d 800MPa, 0.2 \u003d 650MPa, \u003d 11%, \u003d 40%.

Chrome vanadium steels... Alloying chromium steel with vanadium (0.1-0.2%) improves mechanical properties (steel 20HF). In addition, chrome vanadium steels are less prone to overheating. They are used only for the manufacture of relatively small parts.

Typical curriculum

Typical curriculum is a document designed to implement state requirements for a minimum of the content and level of training of graduating schools of secondary specialized education. It defines a general list of disciplines, and the required amount of time for their implementation, types and minimum duration of practice, an approximate list of classrooms, laboratories and workshops. The curriculum also provides for course design in no more than three disciplines throughout the entire period of study. The types of industrial practice and their duration are determined in accordance with the typical educational practice for a given specialty. The schedule of the educational process is of 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 winter and summer holidays ending the academic year (see Table 1).

TABLE 1

Name

educational process,

academic disciplines

Distribution by semester

Number of control

Number of hours

Distribution by courses and semesters

Exams

Course-out project

Theo-ret. busy

Laboratory practice

Materials Science

and electro-radio materials

It can be seen from the curriculum that 60 hours are allotted for the subject of "Materials Science and Electro-Radio Materials". Of these, 44 are theoretical and 16 are practical. The minimum number of tests is 2 tests. There are laboratory classes. Coursework, course project, no credit. The subject "Materials Science and Electro-Radio Materials" is studied in the 2nd year. In the 3rd semester of study 18 weeks, 2 hours per week: 18 * 2 \u003d 36 hours are studied in the 3rd semester. In the 4th semester of study 12 weeks, a week for 2 hours: 12 * 2 \u003d 24 hours are studied in the 4th semester. Total for the 3rd and 4th semester: 36 + 24 \u003d 60 hours, they fully study this subject in the 2nd year.

Thematic plan

Thematic plan - is part of the curriculum. Training program - This is a document that describes the content of the studied material by years of study and sections (topics). The thematic plan consists of sections that include topics. The thematic plan divides the hours into sections out of the total hours. In the thematic plan on the subject "Materials Science and Electro-Radio Materials" in the section "Conducting Materials" 12 hours are given.

TABLE 2

Topic name	Number of hours
		Theoretical lessons
Chapter 4. Conducting materials

High conductivity materials
Superconductors and cryoconductors
Electrical conductivity of conductors
Test

Calendar-thematic plan

Calendar-thematic plan -planning an accounting document, its objectives are to determine the topic, type of method and equipment of lessons in the chosen subject. Drawing up a calendar-thematic plan is the first step in creating a lesson systematization. The original document here is the curriculum. The thematic calendar plan provides for interdisciplinary connections. If the calendar-thematic plan is consistent with the curriculum, they are guided by the thematic plan when drawing up a lesson plan. Calendar-thematic plan (see table 3).

Lesson development

Studying the curriculum, the teacher carefully analyzes each topic, which makes it possible to clearly define the content of training, establish interdisciplinary connections. On the basis of the curriculum, a calendar-thematic plan is drawn up and a lesson plan is drawn up on the basis of the calendar-thematic plan. When defining the purpose and content of the lesson, arising from the curriculum, the content of the record, skills and abilities that students must learn in this lesson are determined. Analyzing the previous lessons, and establishing to what extent their problems have been solved, they find out the reason for the shortcomings, and on the basis of this determine what changes need to be made in the conduct of this lesson. They outline the structure of the lesson and the time for each of its parts, form the content and nature of educational work during the lesson.

Lesson plan

Thing: Materials Science and Electro-Radio Materials Group 636

Topic:Classification and basic properties

a) training: To acquaint students with the concepts and basic properties of conductive materials, talk about their purpose

b) developing: Develop an interest in materials science and electro-radio materials

c) educational: Develop a need for self-education

Lesson type: Combined

Presentation method:search

Visual aids: poster No. 1, PC

Time:90 minutes

During the classes

I... Introductory part:

Written survey on two options + 3 study at the blackboard (appendix 1)

II... Main part:

1. Post the purpose of the new topic

2. Presentation of new material time 40 min.

a) Basic concepts

b) Classification of conductors

c) Scope of application

3. Answers to students' questions time 10 min.

4. Fastening of new material, time 20 min.

Written survey on 2 options + 3 study at the blackboard (Appendix 2)

III... Final part:time 3 min.

1. Summing up

2. Assignment at home: p. 440 answers to questions, independently consider topics No. 2, 3, 4, 5

3. Closing remarks of the teacher

Teacher

List of references

1. Lakhtin Yu. M., Leont'eva VP Materials science. - M .: Mechanical Engineering, 1990

2. Technological processes of engineering production. Edited by S. I. Bogodukhov, V. A. Bondarenko. - Orenburg: OSU, 1996

application1

WRITTEN SURVEYaccording to 2 options

Option 1

1 . That studies the subject of materials science.

2. Types of metals.

3. Classification of metals

4. Allotropic transformation

5 ... Metal properties

Option 2

1. Determination of hardness of metals

2. Mechanical properties

3. Plastic

4. Endurance

5. Technological properties

Appendix 2 Written survey

1 - option

1. Semiconductor materials

2. Superconductors

3. Cryoprobes

4. Characteristics of semiconductor materials

5. Elasticity of materials

Option 2

1. Semiconductor materials.

2. Dielectric materials

3. Plasticity

4. Elasticity

5. Superconductors

application3

Lesson summary on the topic" Conductor Materials"

The growing role of technology and technical knowledge in the life of society is characterized by the dependence of science on scientific and technological developments, increasing technical equipment, the creation of new methods and approaches based on a technical method for solving problems in various fields of knowledge, including military-technical knowledge. The modern understanding of technical knowledge and technical activity is associated with the traditional range of problems and with new directions in technology and engineering, in particular with the technology of complex computing systems, problems of artificial intelligence, systems engineering, etc.

The specification of the concepts of technical knowledge is primarily determined by the specifics of the subject of reflection of technical objects and technological processes. Comparison of objects of technical knowledge with objects of other knowledge shows their certain commonality, extending, in particular, to such features as the presence of structure, consistency, organization, etc. Such common features are reflected in the general scientific concepts "property", "structure", "system", "organization", etc. Of course, the common features of objects of technical, military-technical, natural science and social-scientific knowledge are reflected in such philosophical categories "matter", "motion", "cause", "effect", etc. General scientific and philosophical concepts are used both in the military and in technical sciences. but do not express their specifics. At the same time, they help to deeper, more fully comprehend the content of objects of technical, military-technical knowledge and the concepts of technical sciences reflecting them.

In general, philosophical and general scientific concepts in technical sciences act as ideological and methodological tools for the analysis and integration of scientific and technical knowledge.

A technical object is undoubtedly a part of objective reality, but a special part. Its origin and existence are associated with the social form of the movement of matter, the history of man. This determines the historical nature of the technical object. It objectifies the production functions of society, it is the embodiment of people's knowledge.

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

Its starting point is "human organs". Strengthening, supplementing and replacing working organs is a social necessity, realized through the use of nature and the embodiment of labor functions in transformed natural bodies.

The formation of technology takes place in the process of making tools, adapting natural bodies to achieve the goal. And a hand ax, and a tree trunk that serves as a bridge, etc. - all these are means of strengthening the individual, increasing the efficiency of his activities. A natural object performing a technical function is already a technical object in its potential. It fixes the expediency of its device and the usefulness of constructive improvements due to the part-time work of its parts.

The practical identification of a structure as an integrity indicates the actual existence of a technical object. Its most important properties are functional utility, an unusual combination of materials for nature, subordination of material properties to the relationship between the components of the system. The technical design is the connection of components; this procedure ensures the longest and most efficient operation of the tool, excluding its self-destruction. A part acts as a component of a structure as an initial and indivisible unit for it. And, finally, with the help of technical construction, the way of social activity achieves manufacturability. Technology is that side of social practice, which is represented by the interaction of a technical means and a transformed object, is determined by the laws of the material world and is regulated by technology.

Technical practice reveals itself in the relation of man to technology as an object, to its parts and their connections.

Operation, manufacture and design are closely related to each other and represent a kind of development of technical practice. As an object of exploitation, technology acts as a certain material and functional integrity, the preservation and regulation of which is an indispensable condition for its use. The driving contradiction of operation is the discrepancy between the conditions for the operation of equipment and its functional features. Functionality assumes constant operating conditions, and operating conditions tend to change.

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

The internal contradiction of the technology is the discrepancy between the natural processes used and the needs to increase its reliability and efficiency. Overcoming this contradiction is achieved in the construction of a more perfect technique, with the help of which you can use more fundamental laws of nature. Technique is not passive in relation to technology; the means affects the end.

New technology changes technology, technology itself becomes a means of realizing the internal merits of the constructed technology.

In construction, the social essence of a technical object is most fully revealed. It synthesizes a constructive structure in accordance with the production function set by society. Technology forms a condition for the development of society, mediates its relationship to nature, is a means of resolving the contradictions between man and nature. A technical object is a carrier of production, technological functions of a person. Without technical progress, it is impossible to achieve social homogeneity of society and the all-round development of each individual.

The properties of a technical object are revealed in technical practice and are fixed in the knowledge of the methods of operation, manufacture and improvement of technology. The empirically found proportions between parts of a technical device and the formation of "technical objects", relatively stable information about technical devices, about their essential components and properties. In the form of such objects, for example, descriptions of lifting and transport mechanisms, watches, the most important crafts and materials were formed.

The transition to machine technology, the transfer of working tools to mechanisms brought about the design of technical devices in life, which required the theoretical development of the concept of "machine" and the obtaining of its various idealizations (kinematic pair, dynamics of forces, structure).

The formation of the concepts of technical science is influenced by the regularities revealed in the course of studying the natural sciences, in particular, theoretical mechanics. At the same time, it should be recognized that the concept of a technical design is expressed within technical knowledge. Historically, it is formed as a system of provisions about a machine, a mechanical set of parts and their regular relationship, ensuring the desired effect.

The formation of technical disciplines took place in various ways. Engineering disciplines about motors are based on the results of natural science, on the knowledge of the laws of nature and the application of the laws of physics to technology. Technical kinematics, machine dynamics and the theory of machine parts are of an applied nature. These disciplines were formed on the basis of theoretical mechanics and descriptive geometry, which resulted in the creation of a special language.

Technical sciences were formed not only by applying natural science to technology, but also by using the centuries-old experience of technology, understanding it and giving it a logically clear form. In this way, the sciences of various types of machines, materials science, etc. were formed. The empirical data of these technical disciplines tested in practice were preserved and included in the general science of machines. And until now, many methods of manufacturing and operating equipment have not received proper theoretical justification.

The formation of technical science put an end to the handicraft attitude towards technology, when certain mechanisms were improved in parts over many decades and even centuries. The understanding that a machine is a transformation of motion into a form necessary for production and, in essence, consisting of kinematic pairs, formed the basis for the scientific design of various technical devices in the 19th century.

From what has been said, it is clear that technical science studies its object, although it is able to explain the functioning of handicraft, manual tools, which were created without scientific substantiation. The object of technical science is formed in the process of highlighting the essential and necessary properties of technology, designing a machine. The machine, its components, the relationship between them, their composition, the natural basis of the components and the technological process are all an object of technical science. The object of technical science is a source of scientific and technical knowledge. His research provides, in particular, constructive structures and their elements. The structure fixes stability, repeatability, necessity,

the regularity of the composition of the elements of the machine. In relation to the structure, the component of the machine appears as an element. The mental reception of a structural element is associated with abstraction from the physical dimension and the natural basis of the component. Ultimately, all scientific and technical concepts are a reflection of a technical object.

The concepts "technical object" and "object of technical science" perform a different methodological function in the philosophical analysis of technology and scientific and technical knowledge. The concept of "technical object" captures the side of the objective world that is actually changing in practice. A technical object is displayed in philosophical, social, natural and technical sciences, and each time science isolates its own subject area. The concept "object of technical science" fixes the subject of technical sciences, their relationship to objective reality. The main object of technical sciences is the machine, since with its help the technological process is organized and it is regulated by it. The machine facilitates and replaces human labor, serves as a means to an end.

In technical science, the study of elements, their relationships and technical structures is primarily distinguished. For the formation of the subject of technical science, it is important to highlight, describe and explain the technical elements, their relationships and possible structures in which production functions useful for society materialize. But technical science does not end there. It includes the rules for the synthesis of new technical structures, calculation methods and design forms.

Design rules and norms, graphic and analytical calculation methods bring technical science closer to technical creativity, design and engineering work. The subject of technical sciences is formed in direct dependence on the creativity of technology. This is the specificity of technical sciences, which are a means of improving technology, rethinking natural science data, discovering technological methods and inventing technical structures.

The most important factor of technical creativity is the rules that provide for the achievement of strength and reliability of a technical device, wear resistance and heat resistance of its parts, etc. These rules form a design framework, excluding from it that which does not correspond to the criteria for the functioning of machines developed by technical science. Methods for solving problems are developed on the basis of the rules and norms of engineering activity.

The principles act as prerequisites for activity, as its organizing and guiding principle. Thus, the subject of technical sciences includes not only the laws of a technical object, but also the laws of technical design, methods, rules, norms and principles of engineering design.

Lesson methodology.

I go to room 24, greet the students.

The introductory part of the lesson begins.

I... Introductory part:

1. Organizational moment: check according to the report time 2 min.

I check the presence of students according to the report. I take 2 minutes to check the availability of students in the lesson. Then I do a homework survey.

2. Checking homework: time 15 min.

Interview

I conduct a survey in the form of 10 questions. They include questions on the topic covered. I take 15 minutes for the test.

TEST

1 . What studies the subject of materials science

2. Conducting materials

3. Semiconductor materials

4. Dielectric materials

5. Varnishes

6. Compounds

7. Glue

8. Durability

9. Elasticity

10. Plasticity

Structural steels and alloys

Structural steels are those intended for the manufacture of machine parts (machine-building steels), structures and structures (building steels).

Carbon Structural Steels Carbon structural steels are classified into ordinary grade and high grade steels.

Steels of ordinary quality are made of the following grades St0, St1, St2, ..., St6 (with an increase in the number, the carbon content increases). St4 - carbon 0.18-0.27%, manganese 0.4-0.7%.

Steels of ordinary quality, especially boiling ones, are the cheapest. Steels are cast into large ingots, as a result of which liquation is developed in them and they contain a relatively large amount of non-metallic inclusions.

With an increase in the conditional number of the steel grade, the ultimate strength (sw) and yield strength (s0.2) increase and the plasticity (d, y) decreases. St3sp has sv \u003d 380490MPa, s0.2 \u003d 210250MPa, d \u003d 2522%.

From steels of ordinary quality, hot-rolled stock is produced: beams, channels, angles, rods, as well as sheets, pipes and forgings. Steel as supplied is widely used in construction for welded, riveted and bolted structures.

With increasing carbon content in steel, the weldability deteriorates. Therefore, steels St5 and St6 with a higher carbon content are used for elements of building structures that are not welded.

High-quality carbon steels are smelted under more stringent conditions with regard to the composition of the charge and the conduct of smelting and casting. Content S<=0.04%, P<=0.0350.04%, а также меньшее содержание неметаллических включений.

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

Low carbon steels (C<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 lightly loaded parts, critical welded structures, as well as for car parts hardened by carburizing.

Medium-carbon steels (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 steels, in comparison with low-carbon steels, have higher strength at lower plasticity (sw \u003d 500600MPa, s0.2 \u003d 300360MPa, d \u003d 2116%). In this regard, they should be used for the manufacture of small parts or larger ones that do not require through hardenability.

Steels with a high carbon content (0.6-0.85% C) 60, 65, ..., 85 have high strength, wear resistance and elastic properties. Springs and springs, spindles, lock washers, rolling rolls, etc. are made from these steels.

Alloy structural steels

Alloyed steels are widely used in tractor and agricultural machine building, in the automotive industry, heavy and transport machine building, to a lesser extent in machine tool building, tool and other industries. These steels are used for heavily loaded metal structures.

Steels in which the total amount of alloying elements does not exceed 2.5% are classified as low-alloyed, containing 2.5-10% as alloyed, and more than 10% as high-alloyed (iron content is more than 45%).

Low-alloy steels are most widely used in construction, and alloyed steels in mechanical engineering.

Alloyed structural steels are marked with numbers and letters. The two-digit numbers at the beginning of the brand indicate the average carbon content in hundredths of a percent, the letters to the right of the number indicate the alloying element. For example, steel 12X2H4A contains 0.12% C, 2% Cr, 4% Ni and refers to high quality, as indicated at the end of the grade by the letter ²A².

Structural (machine-building) improved alloy steels Steels have a high yield point, low sensitivity to stress concentrators, in products operating under repeated application of loads, a high endurance limit and a sufficient toughness margin. In addition, the tempering steels have good hardenability and low sensitivity to temper brittleness.

With full hardenability, steel has better mechanical properties, especially resistance to brittle fracture - a low threshold of cold brittleness, a high value of the work of crack development KST and fracture toughness K1c.

Chromium steels 30X, 38X, 40X and 50X are used for medium-loaded small parts. With increasing carbon content, strength increases, but ductility and toughness decrease. The hardenability of chromium steels is low.

Steel 30Kh - sv \u003d 900MPa, s0.2 \u003d 700MPa, d \u003d 12%, y \u003d 45%.

Chrome-manganese steels. Joint alloying with chromium (0.9-1.2%) and manganese (0.9-1.2%) makes it possible to obtain steels with a sufficiently high strength and hardenability (40KhG). However, chromium-manganese steels have a lower toughness, an increased threshold of cold brittleness (from 20 to -60 ° C), a tendency to temper brittleness and austenite grain growth upon heating.

Steel 40KhGTR - sv \u003d 1000MPa, s0.2 \u003d 800MPa, d \u003d 11%, y \u003d 45%.

Chrome-silicon-manganese steels. Chromosilicon-manganese steels (chromansil) have a high set of properties. Steels 20KhGS, 25KhGS and 30KhGS have high strength and good weldability. Chromansil steels are also used in the form of sheets and pipes for critical welded structures (aircraft construction). Chromansil steels are prone to reversible temper brittleness and decarburization when heated.

Steel 30KhGS - sv \u003d 1100MPa, s0.2 \u003d 850MPa, d \u003d 10%, y \u003d 45%. Chromium-nickel steels have high hardenability, good strength and toughness. They are used for the manufacture of large items of complex configuration, operating under dynamic and vibration loads.

Steel 40KhN - sw \u003d 1000MPa, s0.2 \u003d 800MPa, d \u003d 11%, y \u003d 45%.

Chromium-nickel-molybdenum steels. Chromium-nickel steels have a tendency to reversible temper brittleness, to eliminate which many small-sized parts of these steels are cooled after high tempering in oil, and larger parts in water are additionally alloyed with molybdenum (40XH2MA) or tungsten to eliminate this defect.

Steel 40KHN2MA - sw \u003d 1100MPa, s0.2 \u003d 950MPa, d \u003d 12%, y \u003d 50%.

Chromium-nickel-molybdenum-vanadium steels have high strength, ductility and toughness and a low cold brittleness threshold. This is facilitated by the high nickel content. The disadvantages of steels are the difficulty of cutting them and their high tendency to form flakes. Steel is used for the manufacture of the most critical parts of turbines and compressor machines.

Steel 38KhN3MFA - sw \u003d 1200MPa, s0.2 \u003d 1100MPa, d \u003d 12%, y \u003d 50%.

General purpose spring-spring steels

Spring steels are intended for the manufacture of springs, elastic elements and springs for various purposes. They must have high resistance to small plastic deformation, endurance limit and relaxation resistance with sufficient plasticity and toughness.

For springs of small cross-section, carbon steel 65,70,75,85 is used. Steel 85 - s0.2 \u003d 1100MPa, sw \u003d 1150MPa, d \u003d 8%, y \u003d 30%.

More often, alloy steels are used for the manufacture of springs and springs.

Steels 60S2KhFA and 65S2VA, which have high hardenability, good strength and relaxation resistance, are used for the manufacture of large, highly loaded springs and springs. Steel 65S2VA - s0.2 \u003d 1700MPa, sw \u003d 1900MPa, d \u003d 5%, y \u003d 20%. When elastic elements operate under strong dynamic loads, steel with nickel 60C2N2A is used.

For the manufacture of automotive springs, steel 50HGA is widely used, which is superior in technical properties to silicon steels. For valve springs, steel 50HFA is recommended, which is not prone to overheating and decarburization.

Ball bearing steels

For the manufacture of rolling elements and bearing rings of small sections, high-carbon chromium steel ShKh15 (0.95-1.0% C and 1.3-1.65% Cr) is usually used, and for large sections, chromium-manganese steel ShKh15SG (0.95-1.05% C, 0.9-1.2% Cr, 0.4-0.65% Si and 1.3-1.65% Mn), calcined to a great depth. The steels have high hardness, wear resistance and resistance to contact fatigue. Steels are subject to high requirements for the content of nonmetallic inclusions, since they cause premature fatigue failure. Carbide heterogeneity is also inadmissible.

For the manufacture of rolling bearing parts operating under high dynamic loads, case-hardened steels 20X2H4A and 18XGT are used. After gas carburizing, high tempering, quenching and tempering, bearing parts made of steel 20X2H4A have 58-62 HRC on the surface and 35-45 HRC in the core.

Wear resistant steels

High-manganese cast austenitic steel 110G13L, containing 0.9-1.3% C and 11.5-14.5% Mn, is used for parts working for wear under abrasive friction and high pressures and impacts. It has the following mechanical properties: s0.2 \u003d 250350MPa, sw \u003d 8001000MPa, d \u003d 3545%, y \u003d 4050%.

Steel 110G13L has high wear resistance only under shock loads. At low shock loads in combination with abrasive wear or with pure abrasive wear, the martensitic transformation does not occur and the wear resistance of 110G13L steel is low.

For the manufacture of blades of hydraulic turbines and hydraulic pumps, ship propellers and other parts operating under wear conditions during cavitation erosion, steels with unstable austenite 30X10G10.0X14AG12 and 0X14G12M are used, which undergo a partial martensitic transformation during operation.

Corrosion-resistant and heat-resistant steels and alloys

Heat-resistant steels and alloys. An increase in the scale resistance is achieved by introducing mainly chromium into the steel, but also aluminum or silicon, i.e. Elements that are in solid solution and form protective films of oxides (Cr, Fe) 2O3, (Al, Fe) 2O3 during heating.

For the manufacture of various kinds of high-temperature installations, parts of furnaces and gas turbines, heat-resistant ferritic (12X17.15X25T, etc.) and austenitic (20X23H13, 12X25N16G7AR, 36X18H25C2, etc.) steels are used,

having heat resistance. Steel 12Kh17 - sv \u003d 520MPa, s0.2 \u003d 350MPa, d \u003d 30%, y \u003d 75%.

Corrosion-resistant steels are resistant to electrochemical corrosion.

Steel 12X13 and 20X13 are used for the manufacture of parts with increased ductility that are exposed to shock loads (valves of hydraulic presses, household items), as well as products that experience the action of slightly aggressive environments (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 an operating temperature not lower than -20 ° C.

I come to the final part of the lesson, in which I summarize the lesson. I highlight the main points of the topic, emphasize the need to learn this topic. I give out homework. I will sum up the lesson. I give grades to active students to encourage their self-education needs.