High-velocity oxy-fuel coating of AMDRY 9954 on to Ti-6Al-4V alloy: Fracture toughness measurement

High-velocity oxy-fuel (HVOF) coating of AMDRY 985 on to Ti-6Al-4V alloy is carried out and fracture toughness of the coating is examined using indentation tests. The workpiece coated was heat treated for 1 h at annealing temperature to resemble the high heating ambients found in practice. Three-point bending test data are used to determine Young's modulus of the coating prior to and after heat treatment. It is found that heat treatment enhances the oxidation levels in the surface region of the coating, which then acts like the centres for early crack initiation. Once the crack formed at the surface reaches the coating substrate interface, total failure of the coating results.