SCHUBERT Jan Výzkumný a zkušební ústav Plzeň s.r.o.

Spoluautoři HOUDKOVÁ Šárka, ČESÁNEK Zdeněk, KAŠPAROVÁ Michaela

Thermal sprayed coatings based on tungsten carbide are the most durable and much sought materials in terms of wear resistance. Although they are not suitable for high temperature applications, they can be applied in many areas of industry due to the combination of very hard carbides and tough matrix. The hardness and toughness rate of WC-Co coatings is, in the case of thermal sprayed coatings, determined by mutual proportion of carbide phase and matrix, and by spraying parameters. The presented study was conducted to determine the effect of spraying parameters and cobalt matrix content on the resulting coating mechanical properties. Samples were prepared using the HVOF (high velocity oxy-fuel) spraying equipment TAFA JP-5000. Three powder types with different cobalt matrix content, namely WC-12Co, WC-17Co and WC-25Co, were used. Two sets of samples ware prepared in order to determine the effect of spray parameters on the final properties of the coatings from each of powder. The first set was prepared using the default parameters. Spraying of the second set was carried out by different parameters that were newly tested. The basic mechanical properties were evaluated for each of Co content and spray parameters. Special attention was focused on comparison of changes in the abrasive wear resistance evaluated by Dry Sand Rubber Wheel test (performed according to ASTM G-65) and on changes in sliding friction assessed by a test pin-on-disc (according to ASTM G-99). The conclusion of study is devoted to the evaluation of application potential of WC-Co coatings, depending on the preparation parameters and on varying content of Co matrix.