The principles and mathematical modelling of duplex plasma surface engineering systems of steels

摘要

The combined plasma nitriding and PVD ceramic coating duplex process can significantly enhance the tribological and load bearing properties of steels to an extent which cannot be obtained by any individual process. A duplex treated steel component is typical of a multilayer system, where a ceramic coating (e.g. TiN) is on top of the nitrided surface. The mechanical properties of the duplex treated component are therefore complicated functions of the nitriding process conditions and the resultantstructures. In particular they are functions of the thickness and character of the nitrided layers and the ceramic coating, as well as the residual stress distribution in the system. Attempts have been made in the present work to simulate the duplexsystem through process modelling, residual stress simulation, and numerical simulation of the service behaviour of multilayer systems under contact loading conditions. The present paper discusses not only the design principles involved, but also describes the nitriding, residual stress and contact mechanics models for the nitriding/TiN coating system to demonstrate the basis of mathematical modelling of duplex surface engineering.