Development of a wear-resistant self-fluxing thermal spray coating by solid lubricant incorporation

Self-fluxing alloys are an established thermal spray system in case of superimposed tribological and corrosive loads. A dense coating with high bonding strength can be formed by fusing. Such coating systems represent the state of the art in valve technology. Diamond-like carbon (DLC) top coatings are used for friction-reduction. As an alternative approach, this study focuses on the possibility of incorporating solid lubricants in self-fluxing alloy coatings. This allows for higher local stress and failure tolerance. Molybdenum disulfide (MoS₂) was studied as solid lubricant in the self-fluxing alloy NiCrBSiFe. In this preliminary study the optimization of the MoS₂ content with up to 10.0 wt% was performed in spark plasma sintered (SPS) bulk materials. The wear behavior under oscillating wear conditions were investigated. Besides the decrease of coefficient of friction (COF), the wear resistance was increased by incorporating MoS₂. Furthermore, the distribution of the solid lubricants within the SPS bulk material and the influence of the production route was analyzed.