Udo König

Chemical vapour deposition of MoS2 coatings using the precursors MoCl5 and H2S

MoS 2 lubricant coatings were synthesized by low-pressure chemical vapour deposition (LPCVD) using a gas mixture of MoCl 5 , H 2 S and argon. A thermodynamic analysis shows that the deposition of pure MoS 2 can be expected over a wide range of temperatures. Deposition experiments were performed using cemented carbide and silicon substrates. The influence of process parameters on the deposition rate, layer composition and structure of the molybdenum sulphide coatings was investigated. Pure MoS 2 layers can be prepared at substrate temperatures of 500 and 600°C. The chlorine content increases remarkably with decreasing substrate temperature due to the codeposition of ternary MoS x Cl y compounds. At a low n 0 (H 2 S)/n 0 (MoCl 5 ) ratio in the input gas, Mo 2 S 3 is codeposited. Layers deposited at 300°C are amorphous. Between 400 and 600°C, crystalline layers of a different morphology and texture were obtained. TEM investigations show that a preferred orientation of the (002) basal planes exists only for the first range of MoS 2 film growth.

Research, development and performance of cemented carbide tools coated by plasma-activated chemical vapour deposition☆

Abstract The basic research and the development of a plasma-activated chemical vapour deposition (PCVD) process to coat hard metal tools is described. With the new process, coatings of TiN, TiC and Ti(C,N) can be produced. Because of the low deposition temperature, any loss in toughness of the substrates can be avoided. Even complex-shaped inserts can be coated very uniformly without any movement of the substrates during the coating process. Properties such as deposition rates, hardness, composition, adherence and surface performance have resulted in a wide range of applications, some of which are discussed. The PCVD technique has now been introduced as a standard coating technology for hard metal inserts. As a new development the deposition of alumina coatings by the pulsed PCVD process is described. In addition to the coatings of the TiCN system the fine-grained alumina layers open up a wide range of new applications for PCVD technology.

Plasma chemical vapour deposition of aluminium oxide on hardmetals

Abstract Tests were carried out on Al 2 O 3 coatings which had been desposited on hardmetals using a new plasma CVD technique. With this technique hard crystalline Al 2 O 3 layers with good adhesion properties were obtained at temperatures over 450–650 °C. The coatings display a very fine-grained microstructure and, owing to the low coating temperatures, have only a very small influence on the toughness of the coated hardmetals. It was possible in various cutting tests to demonstrate the excellent tool life of indexable inserts coated with Al 2 O 3 by PCVD.