Abstract
Porosity is an important coating feature which strongly influences coating properties.
Porosity creates poor coating cohesion and allows for higher corrosion rate and wear, and is
generally associated with a higher number of unmelted or solidified particle that become
trapped in the coating [1]. This investigation was conducted to investigate the effect of
porosity on the hardness and corrosion resistance of WC-17Co coating on metal substrates.
Coating of about 200μm were successful deposited by HVOF techniques unto four metal
substrates, namely brass, 304L stainless steel, super-invar and aluminium. The corrosion
behaviour was examined in chloride medium using direct current (DC) polarization test. The
Vickers hardness was undertaken at loads of 5 kg for 10 s. The microstructures of the
coatings were studied before and after the corrosion tests by scanning electron microscopy
with EDX. The results indicated a strong correlation between porosity and corrosion rate, as
well as hardness of the WC-17Co coatings.