Abstract
Wear properties of WC/Co cermet coatings have been investigated prepared by cold spraying. Influence of cobalt contents (12~25wt.%), WC particle size (0.2 and 1.8 µm) and agglomerated-and-sintered powder size (-20+0 and - 45+15 µm) on abrasive wear resistance, micro hardness and coating structure is studied, in detail. It has been found that both smaller WC particle and decrease of cobalt content are effective to produce dense, hard and highly wear resistant coating. Smaller powder size is also favorable to make a coating with high mechanical properties. As a result, the cold sprayed coating from WC(0.2 µm)/12wt.%Co with powder size of -20+0 µm has best mechanical properties within this study. This coating has high uniformity and high density with little pores compared to conventional HVOF sprayed coatings. Abrasive wear resistance of the cold sprayed coating, investigated using Suga-abrasion tester, has been almost comparable to HVOF sprayed coating prepared from same feedstock. Strong correlation is also seen between Vickers hardness and abrasive wear resistance. Microstructural analysis suggests that further improvement of coating uniformity by decrease of small pores with the size of sub micron and homogeneous dispersion of WC grains in the cobalt matrix is required to improve the mechanical properties.
