Preparation and coating advantages of nano-WC/Co powder

       Researchers from RUTGERS University in the United States and the United States Naval Research Laboratory jointly developed a patented technology for preparing nano-WC/Co powder. This technology is called the jet conversion process. The process can be roughly divided into three steps:



The first step is solution mixing, that is, the hydrates of W and Co are mixed; the second step is to make the mixed hydrate into precursor particles by spray drying; the third step is to reduce the precursor particles by thermochemical conversion method and carbonization to make WC/Co powder with nano-scale grains, the size of which is tens of microns. One of the advantages is that the mechanical properties of nanostructured WC/Co are far superior to traditional WC/Co powders. The hardness of the nanostructured WC/Co powder is twice that of the traditional WC/Co powder, and it is also far superior to the traditional WC/Co in terms of crack resistance and wear resistance. In addition, the second feature of nanostructured WC/Co is that the cutting tool sintered with it has nanometer grain size, which can make the workpiece surface with nanometer surface roughness. The third advantage of the WC/Co powder produced by the above process is that the WC and Co are uniformly mixed. The research of AHDent et al. shows that the coatings prepared by spraying WC/Co series nanostructure powders by HVOF technology, especially the WC/12Co and WC/15Co nanostructure coatings, have better wear resistance than conventional micro-WC coatings performance. In the nanostructured WC-Co coating prepared by HVOF, it can be observed that the nano-scale WC particles are uniformly distributed in the amorphous Co-rich phase, and the WC particles are well combined with the matrix phase. The microhardness of the coating is significantly increased, and the wear resistance of the coating is improved.



At present, HVOF technology is considered to be an ideal technology for the preparation of high temperature wear-resistant coatings. The successful preparation of WC/Co series nano-coatings will greatly broaden the application prospects of HVOF technology in the field of wear-resistant.