Tungsten carbide (WC) has been suggested as a new buffer layer for the GaN-on-Si technology. We have investigated and optimized the sputtering condition of WC layer on the Si-substrate. We confirmed the suppression of the Si melt-back phenomenon. In addition, surface energy of WC/Si layer was measured to confirm the possibility as a buffer layer for GaN growth. We found that the surface energy(γ=82.46 mJ/cm²) of WC layer is very similar to that of sapphire substrate(γ=82.71 mJ/cm²). We grow GaN layer on the WC buffer by using gas-source MBE, and confirm that it is available to grow a single crystalline GaN layer.

An optical lens is usually produced in the manner of high temperature compression molding with tungsten carbide alloy molding cores, it is necessary to develop and study technology for super-precision processing of molding cores and coating the core surface. As main methods used in surface improvement technologies using thin film, DLC present high hardness, chemical stability, and outstanding durability of abrasion to be extensively applied in various industrial fields. In this study, the effect of DLC coating of a thin film by means of the FVAS (filtered vacuum arc source) analyzed the characteristics of thin film. Surface roughness before and after DLC coating was measured and the result showed that the surface roughness was improved after coating as compared to before coating. In conclusion, it was observed that DLC coating of the ultra hard alloy core surface for molding had an effect on improving the surface roughness and shape of the core surface. It is considered that this will have an effect on improving abrasion resistance and the service life of the core surface.

Rhenium-Iridium(Re-Ir) thin films were deposited onto the tungsten carbide(WC) molding core by sputtering system. The Re-Ir films were prepared by multi-target sputtering with iridium, rhenium and chromium as the sources. Argon and nitrogen were inlet into the chamber to be the plasma and reactive gases. The Re-Ir thin films were prepared with targets having atomic percent of 3:7 and the Re-Ir thin films were formed with 240 nm thickness. The Re-Ir thin films on tungsten carbide molding core were analyzed by scanning electron microscope(SEM) and surface roughness. Also, adhesion strength and coefficient friction of Re-Ir thin film were examined. The Re-Ir coating technique has been intensive efforts in the field of coating process because the coating technique and process have been their feature, like hardness, high elasticity, abrasion resistance and mechanical stability and also have been applied widely the industrial and biomedical areas. In this report, tungsten carbide(WC) molding core was manufactures using high performance precision machining and the efforts of Re-Ir coating on the surface roughness.