A Comparative Study on HVOF, Vacuum Plasma Spray and Axial Plasma Spray for CoNiCrAlY alloy deposition

摘要

In the aerospace field as well as in the stationary gas turbine field, thermal sprayed coatings are used to improve the surface properties of Nickel-super-alloys materials. Coatings are commonly used as bond coat and antioxidation materials (mainly MCrAlY alloys) and as thermal barrier coatings (mainly Yttria partially stabilized Zirconia) In the present study, our purpose was to assess the properties of thermally sprayed bond coat CoNiCrAlY comparing the performance of three different techniques: Vacuum Plasma Spray (VPS), High Velocity Oxygen Flame (HVOF) and Axial Plasma Spray (AxPS). The quality of the deposited films has been assessed and compared from the point of view of structural (porosity, oxide concentration, unmelted particles presence) and mechanical characteristics (hardness, adhesion). Furthermore, a study of the surface composition and morphology has been carried out. Specific efficiency trial has been carried out to compare the efficiency of the three examined technologies. We observed that the highest quality films are obtained by VPS, but that also HVOF and AxPS sprayed films have interesting properties which can make their use interesting for some applications in view of the lower cost of HVOF and AxPS.