Three kinds of Cr3Cr2-25%NiCr coatings prepared by APS-Ar/H-2, APS-Ar/
He and HVOF spraying, respectively, have been studied with a self-made
impact wear rig. The wear resistant performances of Cr3C2-25%NiCr coa
tings were tested under different impact stress. The wear losses and w
orn surface profiles an measured, and the corresponding wear mechanism
s were studied with Scanning Electronic Microscope (SEM). It is found
that wear resistance of Cr3C2-25%NiCr coatings under different impact
conditions increases in the order of APS-Ar/H-2 APS-Ar/He and HVOF spr
aying. The HVOF sprayed Cr(3)C(2)25%NiCr coatings show the best impact
wear resistance due to the denser structure and fewer defects. The we
ar mechanisms of Cr3C2-25%NiCr coatings under impact condition is impa
ct fatigue, which consists of two wear processes of plastic smearing a
nd breaking-off. The plastic smearing produces plastic deformation of
the thin layer in the outer coatings and then causes microcracks in th
e near subsurface due to stress accumulation. There are horizontal and
perpendicular microcracks. The former commonly nucleate from the boun
dary of lamellae, while the latter may occur from the sub-microcracks
inside lamellae. The propagating and merging of both horizontal and pe
rpendicular microcracks finally give rise to the breaking-off of coati
ngs. The cohesive defects such as stratification, porosity and microcr
acks in the lamellae have much effects on the wear resistance of coati
ngs.