Introduction in industry of a duplex treatment consisting of plasma nitriding and PVD deposition of TiN

Abstract

Abstract Recent results point out that it is possible to optimize the adhesion of a TiN coating on some pre-nitrided tool steel surfaces. This combination of plasma nitriding and physical vapour deposition (PVD) TiN coating has been investigated in various research groups as part of a broader objective to obtain an enhanced wear resistance of tools. The implementation of these results in industry, however, usually faces upscaling problems which hinder an efficient evaluation of the industrial performance. Two industrial applications were chosen to demonstrate the possibilities of tools treated by the duplex process. A steel milling tool consisting of 14 high speed steel teeth and knives made out of M2 tool steel for tube cutting were plasma nitrided and subsequently PVD coated. By application of various intermediate steps between nitriding and coating, a good coating adhesion could be obtained. The adhesion behaviour of both coating systems was evaluated by scratch tests. This laboratory performance of the duplex treatment was compared with a tool wear and lifetime evaluation in industry after producing a certain number of workpieces. First results point out that the duplex treatment gives a much better wear resistance for both applications. Extrapolation of laboratory performance to industrial conditions seems to be possible only when based on a close collaboration between industry and research groups.