Effect Of Different Content Of TiC On The Microstucture And Properties Of Ni Based Coating By Laser Cladding

In recent years, with the development of laser technology, the application of laser cladding technology is more and more widely. Laser cladding technology can be conducted on a cheap substrate surface by an excellent coating to save precious metals. Because the coating can significantly improve the surface hardness and wear resistance, many domestic and foreign researchers have used many kinds of surface treatment methods on different substrates and have made a wealth of research results in this respect. At present work, a research on the influence of low content TiC on the micro-structure and properties of the cladding layer was conducted.TiC/Ni cladding layers were prepared on the surface of EH36 steel by using CO2 laser processing device. The surface morphology, microstructure, composition and hardness of the Ti C/Ni cladding layers were studied by means of optical microscopy, electron microscopy, EDS and digital micro hardness tester. Moreover, the effect of different TiC content and laser power on the microstructure and property of the TiC/Ni cladding layers is illustratedExperimental results shows as follows. The microstructure of Ni cladding layer is dense and no obvious fault. The grains of TiC/Ni cladding layer becomes smaller and smaller when more reinforced particles TiC are added. TiC is decomposed by laser irradiations, which promotes the nuclear of melt and then refine the grains. Big holes are found in the layers with 5%TiC, but less holes in the layers with 2% and 8% TiC. The size of TiC particles are between 200 nm and 24μm. The big TiC particles are oval with smooth edge, while the small TiC particles which aggregate on the grain boundary are polygon shape. The micro-hardness of the cladding layers increases with increasing TiC content. 2%TiC is 415 HV,5%TiC is 442 HV,8%TiC is 721 HV. They are higher than the 300 HVmicro-hardness of the EH36 substrate.