Adhesion improvement of cubic boron nitride film on high speed steel substrate by BNX implanted buffer interlayer

One of the major problems for the deposition of cubic boron nitride(c-BN) films on W6Mo5Cr4V2 high speed steels(HHS) is the poor adhesion of the film to the substrate. For the purpose of improving adhesion, the BNX implanted buffer layer was introduced between the HSS and c-BN film deposited by the RF-magnetron sputtering. The influence of the BNX buffer layer on adhesion was investigated and the results showed that when the N/B ratio of the buffer layer is about 1:1, the adhesive strength of c-BN film to the HHS substrate reached the maximum, about 28.47 N, which is sixteen times higher than that of c-BN film deposited without the buffer layer. According to the XPS analysis, the surface of buffer interlayer was mainly in BN phase, which is the main reason to reduce the internal stress and improve the adhesion strength of c-BN films.