Effect of APS process parameters on high-temperature wear behavior of nickel-graphite abradable seal coatings

It has been a while since abradable coatings have been used in turbine engines to seal the gap between rotating and stationary components to protect these parts and increase the efficiency of engines. The properties of these coatings should satisfy the need of low wear resistance to seal the gap without any damage to the parts involved, and high erosion resistance against compressed air trying to pass through the gap. Many parameters are involved in order to tailor the coatings' properties to the needs; in this work, the effect of atmospheric plasma spraying (APS) process parameters such as hydrogen flow rate as the secondary plasma gas and spraying distance on wear behavior of nickel-graphite (Ni-G) abradable seal coatings at 400 °C have been investigated. The results showed these parameters have a direct impact on the hardness, adhesion strength, coefficient of friction and consequently wear resistance of the coatings.