High Temperature and High Pressure Corrosion Behavior of Nickel Based Tungsten Carbide Coating in Saturated H₂S Aqueous Solution

The high temperature and pressure corrosion behavior of laser cladded nickel based coating with a spherical tungsten carbide hard phase in H2S saturated aqueous solution at different times in an autoclave was studied. The microstructure and composition of corrosion products were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractom (XRD). The results indicated that with the increase of time, the corrosion of coating became more and more serious. The highest average corrosion rate was about 0.288 mg/(h·cm2). The coating gradually formed a compact corrosion layer about 5 μm. Corrosion products were mainly Ni(OH)2 and Ni3S2. The coating surface exhibited pitting accompanied by cracks.