Cladding ( French plaquer - apply, cover), thermomechanical coating - applying a thin layer of another metal or alloy to the surface of metal sheets, plates, wire, pipes in a thermomechanical way.
Cladding Processes
It is carried out in the process of hot rolling (for example, cladding of sheets and plates), pressing (cladding of pipes), and also by explosion welding [1] . It consists in the joint hot rolling or drawing of the base and protective metals . The adhesion between metals is carried out as a result of diffusion under the influence of joint deformation of the hot workpiece. The protected metal ( steel , titanium alloys ) is coated on one or both sides with copper , tompak , corrosion-resistant steel , aluminum .
Clad wire is made by drawing the pipe, into which a core of another metal is inserted.
The purpose of cladding is to create a layer of material with special properties (high hardness , corrosion and / or wear resistance, etc.) on the surface of the part, which is used in the manufacture of parts / equipment or in the restoration of their shape after wear . Moreover, the thickness of the cladding layer can be from tenths of a millimeter to several millimeters.
The disadvantages of cladding are the high cost of the method and accelerated corrosion in the weld zone.
Types of cladding
Cladding can be single or double-sided.
Application
Cladding is used in the manufacture and repair of parts that are exposed to aggressive media (dirt, slag, steam) in order to save expensive materials. It is used to obtain bimetal and trimetal , to create an anticorrosive layer of aluminum on sheets, plates, pipes of aluminum alloys, applying a brass coating to steel sheets (instead of electrolytic coating), etc. It is also used in jewelry, for example, an overlay in the form of gold superimposed on silver (silver with gold). Cladding is widely used in the manufacture of coins - for example, coins of 1 and 5 kopecks (steel plated with cupronickel ), 10 and 50 kopecks (steel plated with tompak - from 2006 to 2014) and 5 rubles (copper plated with cupronickel - until 2009) . [2] In nuclear reactor vessels, cladding with stainless austenitic steel uses the inner surface of the vessel, since the main material of the vessel (pearlitic high-temperature steel) is susceptible to corrosion at high temperatures.
See also
- Thermal spraying is a more modern alternative to cladding to overcome the problem of welds.
Notes
- β Lysak V.I., Kuzmin S.V. Explosion welding . - M .: Mechanical Engineering-1, 2005 .-- 543 p. - 500 copies. - ISBN 5-94275-220-6 .
- β Coins | Bank of Russia . Date of treatment February 28, 2013. Archived March 10, 2013.