Influence of spraying parameters on the diamond decomposition of HVOF-sprayed nickel-diamond coatings

摘要

Diamond is the hardest known material and hence is suitable for a large, diverse field of applications for industrial processing tools. Different types of diamonds are used for these tools. For example, large diamonds are frequently used to industrially process minerals, while fine diamonds are used to process glass or carbon fibre reinforced plastic, as well as for grinding and lapping processes. A major challenge when processing diamonds is the process temperature as diamonds show decomposition effects at higher temperatures. Thermaly spraying processes, which have the advantage of having only a small thermal influence on diamonds due to the short dwelling time of the particles in the flame, are going to be investigated as an alternative processing method for diamond-reinforced coatings. Additionally, these processes are flexible regarding the applicaton process of contour accurate coatings. This paper gives an insight into the relationship between spray process parameters and the diamond decomposition concerning the particle temperature during the spraying process. For this purpose, the process parameters are varied and the resulting coatings are characterized, analyzing their influence on the diamonds in the coating. One focus of this paper is the scanning electron microscopical investigation of a thermally induced carbonating of the diamonds.