Конструкциялық материалдар және термоөңдеу Конструкционные материалы и термообработка Constructional materials and heat treatment Учебное пособие для специальности: 5В071200– «Машиностроение»



Pdf көрінісі
бет54/77
Дата06.07.2022
өлшемі1,99 Mb.
#37521
1   ...   50   51   52   53   54   55   56   57   ...   77
Байланысты:
montaev s h

Steel with special properties
In the industry widely use steel and the alloys possessing special properties: 
the set conductivity, the low specific electrical resistance set by temperature 
factor of linear expansion, semi-conductor and magnetic properties, ability to get 
into condition set products. 
Wide application was found by metals and alloys of high conductivity: silver, 
copper, bronze and brass. 
Silver is applied to manufacturing of not oxidized conductors of electric 
contacts of responsible devices. Special methods from silver produce coverings 
on copper, brass and non conducting materials: ceramics, glass, polymers. 
Copper has wide application thanks to high conductivity, good mechanical 
characteristics, lower in comparison with cost silver. For protection of copper 
against oxidation current carrying elements to silver. 
In products with the raised mechanical characteristics use brass, cadmic and 
beryllium bronze. 
Cadmic bronze use for manufacturing of sliding contacts, membranes. 
Brass apply to manufacturing of various current-carrying details. 
Aluminum is characterized by rather high electrical- in a combination to 
plasticity and small density. It is more widespread in the nature, than copper, is 
more resistant to corrosion. 
Semi-conductor materials represent a class of materials with the electronic 
conductivity, being characterized a bigger specific electrical conduction, than 
metals, but smaller, than dielectrics. For receiving semiconductors with the set 
specific electrical resistance and type of conductivity carry out their alloying. 
According to chemical classification of semi-conductor materials, they are
divided into two classes: 


193 
- the simple semiconductors incorporating one element., 
- the difficult semiconductors being chemical compounds and alloys. 
Magnetic steel and alloys characterize magnetic permeability, coercive force 
and a residual induction. Depending on values of these sizes magnetic materials 
divide on: 
- magnetic and soft materials (ferromagnetic), having small coercive force and 
big magnetic permeability. They are electro-technical iron and steel, iron-nickel 
alloys (permalloy)., 
- magnetic and firm steel and alloys having big coercive force. These are high-
carbonaceous and alloyed became, special alloys. 
Alloys with high electric resistance are applied to manufacturing of electro-
heaters and elements of resistance (resistors) and rheostats. 
In the industry wide application was received by the materials possessing high 
a limit of elasticity and a limit of endurance. These properties of materials are 
provided with their thermal processing - training and the subsequent water-
tempering. Medium-carbon steel with elastic properties apply to manufacturing 
of springs, springs of general purpose. To manufacturing of elastic elements in 
instrumentation apply alloys with special elastic characteristics. Springs, 
membranes, bellows-produce from alloys 42НХТЮ, 17ХНГТ, 68НХВКТЮ, 
etc. These alloys in the tempered condition are rather technological in 
processing, and after aging gain high elasticity and durability. 
Alloys with set by factor of thermal expansion contain a large amount of 
nickel. The alloy 36Н-an invar, doesn't extend almost at temperatures from a 
minus 60 to +100?С, possesses good office characteristics, is technological and 
corrosion-resistant. Invar alloying cobalt receives a super invar. These alloys 
apply to manufacturing of details of the devices demanding the constant sizes in 
the range of climatic changes of temperatures. 
For connection of metal details of devices with the glass apply the alloys of 
Fe-Ni alloyed by cobalt or copper. To connections with heat-resistant glass 
apply an alloy 29НК (29 % of nickel and 18 % of cobalt) - cover. To not heat-
resistant glasses apply an alloy 48Н-platynite. 
In instrumentation widely use the materials consisting of two layers of 
materials with various temperature factors of foundry expansion – thermo 
bimetals. Thermo bimetals apply to manufacturing of thermal relays, condensers 
and alarm fire devices. 


Достарыңызбен бөлісу:
1   ...   50   51   52   53   54   55   56   57   ...   77




©emirsaba.org 2024
әкімшілігінің қараңыз

    Басты бет