Influences of gas flow rates on melting of particles of HVOF sprayed CoCrW coating and coating properties

摘要

This paper discussed influences of flow rates of O_2, C_3H_8, and compressed air on the melting degree of particles during HVOF (high velocity oxy-fuel) sprayed CoCrW coating. The O_2 flow rate has the maximal effect on the melting of particles, the C_3H_8 flow rate has the second, and the compressed air flow rate has the minimal effect. The bond strength of the HVOF sprayed CoCrW coating is over 54 MPa. The porosity ratio of the HVOF sprayed CoCrW coating after optimization of gas flow rates is less than 2%. The average microhardness of the coating is up to HV_(0.1) 545. The oxidation amount per unit area of the HVOF sprayed CoCrW coating increases with the holding time increasing at 800℃. In the same way, the oxidation amount of the coating increases as the temperature increases. Particularly, the oxidation of the coating drastically increases over 850℃.