Scope of bimetallic materials is very extensive: oil and gas complex, nuclear power, stamping of coins, utensils, etc. Bimetals produce a wide range of ways: galvanic, gas-thermal dusting, building up and others.
Bimetal call composite material in which one metal, usually cheaper, is covered by another, more expensive with the best operational characteristics. If the amount of metals is equal in a composite 3, then it is called trimetally. The composition from bigger amount of metals is not applied.
Use of bimetals
Anticorrosion coatings. Everywhere where it is necessary to cover corrosion and weak metal, use copper, nickel, silver or another a covering with the surpassing operational properties. Such bimetal is actively used for production of the noncorrosive equipment of the oil and gas and nuclear power equipment, chemical ware, kitchen utensils and the plated coins.
Thermosensitive elements. Selecting metal with different coefficients of thermal expansion it is possible to achieve receiving bimetal which will be deformed towards metal with smaller coefficient of thermal expansion. Antifriction coverings. Such bimetal will be at the same time cheap and resistant to attrition.
Ways of production of bimetals
Galvanic. When passing electricity through solution there are Faraday processes, for example, metal is besieged. Selecting a certain structure of electrolyte, solution temperature, composition of solution, try to obtain sedimentation on a surface of a metal covering with the set properties. For example, the most plain electrolyte for sedimentation of a brilliant copper covering has to contain copper sulfate, sulfuric acid and gelatin. Process is carried out at the room temperature at current 1-5 And/sq.dm. Gas-thermal dusting. Metal is transferred to the dispersed state and a gas or plasma stream moves on a substrate on which it is condensed. Building up by electric or plasma heating. Simultaneous hire. Immersion in fusion. Explosive welding. Two rolled sheets of metal have in parallel. On the one hand conduct controlled explosion which brings two leaves into close contact. Svarivaniye occurs due to simultaneous deformation.
Shortcomings of bimetals
The main lack of bimetals is an electrochemical corrosion which arises at faces where both metals are at the same time available to the external environment. But, if the electrode potential of a covering is less, than base metal, then the covering provides also tire-tread protection.