Friction and wear properties of (Ti,Mo)(C,N) hardmetal coatings prepared by gas and liquid fuel HVOF processes

Materials based on the cubic hard phase TiC are a highly promising extension and alternative to existing hardmetal coating solutions, such as WC-Co, WC-CoCr and Cr3C2-NiCr. TiC-based compositions, alloyed with Mo and N, consist of two core-rim-structured hard phases embedded in metal binder phase of Co and/or Ni, for example. These materials can be sprayed with various methods, such as plasma spray, detonation gun and HVOF, resulting in competitive coating properties. For example, HVOF sprayed (Ti,Mo)(C,N)-hardmetal coatings show variable friction properties where the coefficient of friction (CoF) is lower when sprayed by gas fuel type whereas liquid fuel type gives higher CoF. However, this conclusion needs to be confirmed, since feedstock powders and measurement equipment have been different that makes prevent simple comparison. In this work, comprehensive studies have been conducted by preparing powder feedstock with Ni and Co binders retaining same manner for various HVOF methods as well as unified measurement conditions for CoF and wear properties.