FUNDAMENTAL AND APPLIED ASPECTS OF THE PLASMA-ASSISTED NITRIDING PROCESS FOR ALUMINUM AND ITS ALLOYS

The insufficient wear resistance of aluminium and its alloys is a well -known problem. Different surface treatment methods have been develope d to increase the resistance. Compared to the electrochemical processe s, the plasma-assisted nitriding of aluminium is a new method without ecological problems. In this paper different possibilities of plasma-a ctivated nitriding are introduced. Due to the low electrical conductiv ity of the aluminium nitride coating formed, an rf plasma process has some advantages compared to a dc discharge. Furthermore, comparisons a re made with high-energy ion implantation and a low-energy ion-assiste d deposition. The morphology and composition of the resulting aluminiu m nitride layers are shown. A sputtering process prior to nitriding is of great importance. The influence of the gas phase composition and t he plasma parameters were examined by plasma mass spectrometry. The io n energy distribution of the detected species indicates different poss ible charge transfer processes which art influenced by the gas phase c omposition. (C) 1997 Elsevier Science S.A.