The following conclusions can be made concerning the wear behaviour of these coatings. 1. Decomposition of the powders on spraying to form a coating results in poor wear resistance compared to the sintered material. Decomposition is highest for the deposition of the NG coating and lowest for the CL coating due to differences in powder type and gun design. Decomposition is promoted by small carbide size within the powder particles and by the conditions within the gas fuelled gun which result in higher particle temperatures and longer residence times within the gas jet. 2. Observation of the wear behaviour of the four materials at the lowest loads tested (where wear rates are technologically interesting) indicate that the sintered material has the lowest wear rate. The wear rate of the NG coating is higher than that of the CG coating since the former material undergoes severe decomposition due to its small grain size. As such, the benefits of sintered nanocomposite materials are not realized. 3. Whilst powder decomposition in the flame is low during spraying of the CL coating, bonding between splats is also limited and thus the coating wears rapidly. 4. Spraying systems, conditions and powders must be optimized to yield as low a level of decomposition within the particles as possible whilst still maintaining enough heat input to result in a strong bond between splats.
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