Three Ni-Cr based powders (Metco 700, Armacor C and PSI-1) have been therma
lly sprayed using the HVOF process. The resultant deposits were then charac
terised using SEM, TEM and XRD. Microhardness surveys were carried out on t
he coatings together with abrasive wear tests. Coatings 250 mu m thick, wer
e produced with low oxides and porosity levels. The most consistent coating
s were prepared from powder sources with a minimum particle size of 25 mu m
. Coating microstructures were either nano-crystalline or mixtures of amorp
hous and microcrystalline phases. Boron additions to the powder encouraged
the formation of amorphous coatings and higher microhardness values i.e. >
675 H nu. The formation of boride precipitates in the coatings does not app
ear to raise their hardness as the precipitates were either of larger diame
ter > 500 nm or present in low volume fractions. Limited amounts of oxides
were produced in the coatings, e.g. as alpha-Cr2O3 or spinel oxide NiCr2O4
particularly at intersplat boundaries. Abrasive wear resistance of the PSI-
1 coating was superior to the other two coatings because it contains more a
morphous material. The combination of wear and corrosion resistance associa
ted with these coatings may prove to be attractive in many applications whe
re both these properties are needed, carbides and borides.