Research On Preparation And Interface Of Copper/steel Bimetal Composite Material

With the development of science and technology, many industries for the comprehensive performance of metal materials have become increasingly demanding. Considering the two aspects of economy and performance, single material can not reach the actual requirements. Copper has excellent ductility, reduce friction and thermal conductivity, but with the development and utilization of copper resources in recent years, copper prices increased year by year. However, steel’s price is cheap and has high strength; copper/steel bimetal composite material instead of a single copper or copper alloy is a good choice. The use of copper/steel bimetal composite material can save a large number of precious metals copper, reducing the cost greatly, and give full play to the superior friction reduction of copper and the high strength performance of steel. Not only improve the comprehensive mechanical properties of copper/steel composite job, but also has good economic benefit and wide range of applications. What’s more, it is also in line with the construction of resource-saving development direction.This paper reviews the current research progress of copper/steel bimetal composite technology, summarizes the copper/steel bimetal composite preparation key technology. By using vacuum diffusion bonding prepared copper/steel bimetal composite, optimized by testing the vacuum diffusion bonding process parameters, in order to obtain the optimum process parameters. When the diffusion temperature were 1080℃, 1120℃, 1130℃, 1135℃ and holding time were 0.5h, 1h, 1.5h,respectively, using vacuum diffusion bonding prepared the copper/steel bimetal composite. By means of optical microscope(OM) and scanning electron microscopy(SEM), the interface microstructure, elements distribution and diffusion mechanism of copper/steel bimetal composite plate are observed at different diffusion temperature and holding time. The results showed that:(1) The vacuum diffusion bonding process can successfully be copper and steel welded together, the bonding interface is good, no cracks, holes and other defects. What’s more, a certain thickness of the diffusion layer formed at the bonding interface, so as to obtain the best quality for copper/steel bimetal samples.(2) As the temperature increases, cracks and holes gradually become smaller until it disappears at the bonding interface, and the bonding areas continue to expand.(3) Under the same conditions of the diffusion temperature and the holding time, Fe element to the copper-side diffusion distance is larger than Cu element to the steel-side diffusion distance. When the diffusion temperature is 1135℃ and the heat preservation time is 1h, Cu, Fe diffusion of elements from the other side to the substrate side is 2.2μm, 1.8μm, respectively.(4) The optimum process parameters of copper/steel bimetal composite plate prepared by vacuum diffusion bonding is: the diffusion temperature is 1135℃, the heat preservation time is 1h, and the diffusion layer thickness is about 2.2μm.