Life improvement of unduplicated tool for deformation processing of aluminum alloy by duplex treated TIN coating

研究了TiN复合处理作为铝合金变形加工刀具潜在的表面改性剂的膜寿命。结果表明：(1)无论回火时间长短，涂层的磨损始于恒定的低磨损率，而在高磨损率下，涂层在空气气氛中发生了向磨损的转变。(2)在氮气气氛中，涂层以铝合金向TiN涂层的转移为主，涂层没有受到磨损损伤。滑动一定距离后，TiN涂层上出现了一小片贝壳状的碎屑。这种细小的切屑在TiN涂层膜的下游和涂层膜-基材界面上生长，导致膜的宏观剥落。(3)TiN-双重处理将等离子氮化工具钢的磨损减少了80%。(4)双重处理的工具钢的氮化基材的回火进一步延长了涂层的寿命两倍以上。(5)施加适当的涂层偏压和氮化层厚度超过70μm，获得了显著的长的膜寿命，这大约是传统双重处理表面的3倍。对于未经回火处理的常规双相处理表面，优化涂层偏压和增加渗层深度均不能提高膜层寿命。

The film life of the TiN duplex treatment was studied as a potential surface modification for tools for deformation processing of aluminum alloy. The following results are obtained.(1) Wear starts with that of coating film at a constant low wear rate irrespective of the tempering duration, and a transition to wear of the substrate at high wear rates takes place in air atmosphere.(2) Transfer of aluminum alloy to the TiN coating film was predominant and the coating film suffered no wear damage in nitrogen atmosphere. After sliding for a certain distance, a small shell-like chipping appeared on the TiN coating film. This small chipping grew downstream within the TiN coating film and along the coating film-substrate interface to cause a macroscopic spalling of the film.(3) TiN-duplex treatment reduces by 80% the wear of plasma-nitrided tool steel.(4) The tempering of the nitrided substrate of duplex-treated tool steel further prolongs the coating film life more than twofold.(5) Applying the appropriate coating bias and the nitrided layer thicker than 70 μm, a markedly long film life, which is about 3 times longer than of the conventional duplex treated surfaces is obtained.(6) On the other hand, for the conventional duplex treated surfaces prepared without the tempering neither optimizing the coating bias nor the increase of the depth of nitrided layer improves the film life.