In this study, a hybrid plasma spraying process is used to produce particle-reinforced metal-matrix composite coatings on 316 stainless steel. Two injectors are mounted at the output of the plasma gun, one feeding a nickel-base alloy powder, the other feeding a suspension of alumina nanoparticles. Different feed rates, suspension compositions, and alumina particle contents are used and their effects on microstructure, microhardness, porosity, adhesion, and wear behavior are assessed.

In nuclear plants, the replacement of hardfacing Stellite, a cobalt-base alloy, on parts of the piping system in connection with the reactor has been investigated since the late 60’s. Various Fe-base or Ni-base alloys, Co-free or with a low content of Co, have been developed but their mechanical properties are generally lower than that of Stellites. The 4th generation nuclear plants impose additional or more stringent requirements for hardfacing materials. Plasma transferred arc (PTA) coatings of cobalt-free nickel-base alloys with the addition of sub-micrometric or micrometric alumina particles are thought to be a potential solution for tribological applications in the primary system of sodium-cooled fast reactors. In this study, PTA coatings of nickel-base alloys reinforced with alumina particles were deposited on 316L stainless steel substrates. The examination of coatings revealed a refinement of the microstructure. Under the conditions of the study, the addition of alumina particles did not improve the micro-hardness of coatings but improve their resistance to abrasive wear.