Study of the Influence of Silicon-Containing Diamond-like Carbon Coatings on the Wear Resistance of SiAlON Tool Ceramics

Abstract

DLC coatings have low adhesive bond strength with the substrate and a high level of residual stresses. This paper is devoted to researching a complex of characteristics of a DLC-Si coating deposited on samples of SiAlON ceramics with intermediate coatings (CrAlSi)N pre-formed to improve the adhesive bond strength employing vacuum-plasma spraying. DLC-Si coatings were formed by chemical vapor deposition in a gas mixture of acetylene, argon, and tetramethylsilane supplied through a multichannel gas purge system controlling the tetramethylsilane volume by 1, 4, 7, and 10%. The SiAlON samples with deposited (CrAlSi)N/DLC-Si coatings with different silicon content in the DLC layer were subjected to XPS and EDX analyses. Tribological tests were carried out under conditions of high-temperature heating at 800C. The nanohardness and elasticity modulus of the rational (CrAlSi)N/DLC-Si coating with Si-content of 4.1% wt. were 26 ± 1.5 GPa and 238 ± 6 GPa, correspondingly. The rational composition of (CrAlSi)N/DLC-Si coating was deposited on cutters made of SiAlON ceramics and tested in high-speed machining of aircraft nickel-chromium alloy compared to uncoated and DLC-coated samples. The average operating time (wear resistance) of (CrAlSi)N/DLC-Si(4.1% wt.)-coated end mills before reaching the accepted failure criterion was 15.5 min when it was 10.5 min for the original cutters.