Alumina deposition by plasma CVD

Research project P 14338 Alumina deposition by plasma CVD J. LAIMER 06.03.2000 Coating with a hard material is nowadays common practice for the improvement of the performance of many kinds of tools. Compared with the titanium-based hard coatings and diamond coatings, hard alumina coatings offer substantial advantages, especially with regard to wear protection at elevated temperatures. Today alumina coatings are commercially produced only by chemical vapour deposition (CVD). In spite of intense research on the deposition of alumina by conventional CVD, it was impossible to deposit hard alumina coatings at temperatures below approximately 900 C. Recent investigations demonstrated the deposition of hard, crystalline alumina phases at substrate temperatures as low as approximately 700 C by plasma-based techniques. We propose a research project which should establish the scientific basis for the deposition of uniform, hard and chemical inert alumina coating by bipolar pulsed d.c. plasma CVD at reduced temperatures. In order to achieve this goal we will investigate the deposition of alumina by bipolar pulsed d.c. plasma CVD in the temperature range of 450 to 900 C. The objectives of the proposed coatings across the reactor. For this reason the influence of plasma chemistry and ion bombardment on film properties, especially hydrogen (hydoxid) incorporation into the alumina coating and occurring crystalline phase, will be investigated. In the coarse of film characterization also the interface to the substrate will be analysed in order to gain information about film adhesion. Additionally, the influence of plasma chemistry, plasma dynamic and process gas distribution on the coatings across the reactor will be studied.