Study of mechanical properties and wear resistance of HVOF CoNiCrAlY/YSZ coatings

In this study effect off adding oxide reinforcement YSZ on mechanical properties and wear resistance of CoNiCrAlY/YSZ coating has been investigated. First, for preparing composite powders CoNiCrAlY with 5, 10 and 15% YSZ were mechanical milled 24 hours. The composite coatings and commercial coating were deposited on Inconel 617 substrate with high velocity oxygen – fuel method. The microstructures, wear resistance, mechanical properties and worn surface morphologies of the coatings were comparatively analyzed as well by means of Scanning Electron Microscopy, energy dispersive X-ray analysis, pin-on disc wear test, micro and macro hardness tests. Results show that with increasing YSZ content unmelted particles increased in composite coatings. Adding YSZ to 10%, increase the hardness of composite coatings, but adding more YSZ to 15% increased porosity in coatings which led to decline in hardness. Adding YSZ to CoNiCrAlY coatings has been increased the wear resistance of composite coating, so that 5% YSZ coating with a protective oxide layer on the wear track has shown lowest level of wear rate.