Thermal spraying of carbide coatings with the oxyfuelionisation process

The oxy-fuel ionisation (OFI) system is a new thermal spray process which basically consists of a high-velocity combustion process enhanced by a lowenergy plasma source. The system is characterised by its stability over a relatively wide range of fuel-to-oxidant ratios and its high productivity using fuels with low gross heating values such as natural gas (methane). This work deals with the development of WC-Co coatings using methane as fuel gas and the experimental validation of the results with the help of a standard on-line diagnostic technique. The process parameters were initially optimised following a large screening spray trial and comparisons of the microhardness distribution over the crosssection of the coatings and their crystallographic structure. The optimised parameter window has then been reduced and validated by experimental results achieved with the on-line diagnostic system.