A study on cutting and tribology performances of TiN and TiAlN coated tools

Abstract

TiN and TiAlN coatings were deposited on the surface of AISI 5140 steel and cemented carbide YT15 by magnetron sputtering technique (MSP). The reciprocating sliding tests of TiN and TiAIN coatings on the surface of AISI 5140 steel were performed to investigate the friction coefficients of coatings affected by various normal loads with friction pair of 304 stainless steel balls. Dry machining tests on AISI 5140 hardened steel were carried out with the TiN and TiAlN coated tools on a CA6140A lathe. The effects of cutting speed on cutting forces and surface roughness of TiN and TiAlN coated tools were obtained and analyzed to assess the cutting performance of coated tools. The microcosmic micrographs of wear areas of coated tools were observed and investigated by scanning electron microscope and energy dispersive spectrum. The results show that the friction coefficients of TiN coatings are lower than that of TiAlN coatings. The cutting force of TiAlN coated tool decreases and flank wear resistance enhances in comparison with TiN coated tool. The wear form and mechanisms of TiN coated tool are mainly crater wear on the rake face and adhesive wear and abrasive wear on the flank face. The wear form and mechanisms of TiAlN coated tool are mainly adhesive wear, the breakage of cutting edge and the damage of tip, accompanied with diffusion and oxidation wear.