Effects of plasma spray distance on properties of Ni-Al intermetallic coating by utilizing of mechanically alloyed powders

摘要

In this research mechanically alloyed Ni-Al powders were used for production of plasma sprayed coatings and effect of spray distance on the phases, microstructure and hardness of the coatings are examined. Three types of Ni-Al powder were made by METCO, LobaChemi and mechanical alloying, were used for comparing coating properties. Coatings are examined by XRD, SEM, EDAX and microhardness measurements. However intermetallic phases were not found in mechanically alloyed powder, but coatings contained these phases. This shows that heat energy of plasma spray caused formation of NiAl phases during flying of particles to substrate or after reaching to substrate. Comparison of coatings properties indicated that mechanical alloying of powders caused improving mechanical properties and decreasing porosity percentage of coatings. Change of spray distance caused changing in phases, porosity percentage and microhardness of coatings. Best spray distance for spraying of the made powder determined as 11 cm.