Microstructure and properties of Cr2O3 coating deposited by plasma spraying and dry-ice blasting

Dry-ice blasting is applied in atmospheric plasma spray process with an aim to improve the properties of Cr2O3 coatings and save the cost. Microstructure, the tensile adhesive strength and the wear resistance of plasma-sprayed Cr2O3 coatings without and with the treatment of dry-ice blasting were compared. The results indicate that dry-ice blasting has a significant effect on the porosity of Cr2O3 coating. After the treatment of dry-ice blasting, the porosity of Cr2O3 coating decreases from 6.6 ± 1.1% to 2.0 ± 0.1% and a noticeable improvement in the adhesion between the coating and 25CrMo4 substrate has been obtained from 13 ± 2 MPa to 46 ± 5 MPa. They could be attributed to the sublimation effect of dry-ice pellets on the evaporated Cr and the cleaning effect of dry-ice blasting on the coated substrate. The dry-ice blasted coating was more wear resistant than that deposited without dry-ice blasting.