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

研究了TiN双相处理作为一种潜在的铝合金变形加工工具表面改性材料的膜寿命。得到如下结果：(1)与回火时间无关，涂层的磨损以恒定的低磨损率开始，在空气环境中过渡到高磨损率的基材磨损。(2)氮气氛下，铝合金向TiN涂层转移为主，涂层无磨损。在滑动一定距离后，TiN涂层上出现了一个贝壳状的小切屑。这个小的切屑在TiN涂层薄膜的下游和沿着涂层-衬底界面生长，导致薄膜的宏观剥落。(3) tin双相处理可使等离子体氮化工具钢的磨损降低80%。(4)经双相处理的工具钢氮化基体的回火进一步延长了涂层寿命一倍以上。(5)采用适当的涂层偏压和厚度大于70 μm的氮化层，可获得较长的膜寿命，约为常规双相处理表面的3倍。(6)另一方面，对于未经回火制备的常规双相处理表面，优化涂层偏置和增加氮化层深度都不能提高膜的寿命。

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.