Thickness-controllable diamond films deposited on stainless steel using a Cr/Cr-Si-N interlayer prepared at different N2/Ar flow ratios

Abstract

It is important to deposit diamond films with controllable thickness on stainless steels to realize their applications in medical apparatus with high precision. Here, the diamond film with various thicknesses was achieved by adjusting the N2/Ar flow ratio in deposition of Cr/Cr-Si-N interlayer. The results show that with the ratio increases, Cr(Si) phase that is easily carbonized in the interlayer gradually decreases, continuously shortening the time for carbon supersaturation and leading to the increase of diamond film thickness. With the ratio reaching 50%, the interlayer consists of (Cr,Si)N phase which has lower carbonization rate than Cr(Si), the film is the thickest. At the ratio larger than 50%, (Cr,Si)2N phase appears which has low unit cell density. Carbon atoms easily diffuse inward through the phase and those for growth of diamond film decrease, so the film becomes thin again. In addition, the adhesion of the diamond film becomes poor when the ratio is 125%, which can be attributed to the outward diffusion Fe atoms due to the small thickness of interlayer caused by the target poisoning effect. This study provides a new pathway for fabricating thickness-controllable diamond film on stainless steels for high precision apparatus applications.