Abstract
In high velocity air fuel (HVAF) spraying process, spraying particle temperature and velocity are one of the most important parameters. The spraying gun nozzle may influence on combustion gas and spraying particle behavior. Longer nozzle may accelerate particles effectively, and convergent-divergent nozzle makes supersonic flow. In this paper, two convergent-barrel-divergent nozzles (CD-nozzle) and a convergent-barrel nozzle (C-nozzle) have been investigated. WC-10mass%Co-4%Cr cermet coatings are produced by each combinations of the nozzle and the combustion chamber. These coatings were studied by micro hardness, abrasive wear resistance, and porosity. As a result, the spraying gun nozzle shape was critically influence on the HVAF cermet coating properties, and a CD-nozzle can produce more wear resistance and dense cermet coating. It is required for further improvement and control coating properties to analyze combustion gas or particle behavior.
