Effect of Plasma Gases on the Structure and Properties of WC-CrC-Ni Coatings

The effect of plasma gases (argon, helium) on the structure and properties of the WC-CrC-Ni coatings deposited at the graphite substrate has been investigated. The coatings were deposited by plasma spraying method in equipment Cham Pro –Thermal Spray Systems produced by Sulzer company. The microstructure of coatings were investigated by light microscopy (MO) and scanning electron microscopy (SEM). The performed investigations have been shown that with the increasing of amounts of argon and reducing volumes of helium and nitrogen, the microhardnees increased. The plasma gases also influenced on the porosity of coatings. Keywords: WC-CrC-Ni coatings, plasma spraying, microstructure, porosity Acknowledgement: The work was supported by project No INNOTECH – K2/IN2/9/181851/NCBR/13

The Research of Thermal Arc Sprayed Coatings Tribological Properties by Using Rubber Wheel Test

This paper present the result obtained from new experimental STEIN-MESYFIL 953 V; STEIN-MESYFIL 954 V coatings. The surfacing material was wires of 1.6 mm diameter. The tests aimed at determining wear resistance of coatings sprayed on steel substrate. The investigation shows that the tribological behaviour of new experimental thermal arc sprayed coatings is greatly affected by its microstructural constituents such as porosity, oxide inclusions, and microhardness of coatings. Results show that increasing porosity of coatings twice, it doubles the mass loss. Results for thermal sprayed coatings of all experiments showed their high wear resistance and are discussed.

HVOF Spraying Process Optimization for the Deposition of Submicron Structural WC-12Co Coatings

The submicron structural WC-12Co coatings were deposited by a high-velocity oxy-fuel (HVOF) system from agglomerated WC-12Co powders with carbide grain size of 0.7~0.9μm in this study. Effects of HVOF spraying parameters on the microstructure and properties of submicron structural WC-12Co coatings were examined. The results showed that both the fuel flow rate and spraying distance influenced significantly the microhardness and porosity of coatings, and cooling condition also had a few effect on the porosity of coatings. Through a series of experiments, the spraying parameters for the WC-12Co coatings preparation were optimized as follows: propane gas pressure was 0.65 MPa, propane flow rate of 16.7 L/min, oxygen pressure of 0.7 MPa, oxygen flow rate of 100 L/min, spraying distance of 270 mm and with compressed air cooling. The porosity of WC-12Co coating sprayed at the optimum parameters was lower than 1%, and its microhardness was HV0.11141±67.