In this study, composite powder (MEC1031C) was modified with the addition of 0.4 wt.% La2O3. The effects of La2O3 addition on microstructure, formation of new phases, and microhardness were studied. The La2O3 addition refines the microstructure, forms new phases, and increases microhardness of high-velocity oxy-fuel (HVOF) coatings. The erosive wear behaviours of HVOF-sprayed coatings were investigated by response surface methodology. To investigate and develop the erosive wear model of unmodified (without La2O3) and modified (La2O3 addition) HVOF-sprayed coatings, four factors, velocity (V), impact angle (A), temperature (T), and feed rate (F), with each factor at three levels, were used. Analysis of variance was carried out to determine the significant factors and interactions. Investigation showed that the velocity, temperature, and feed rate were the main significant factors, while velocity–feed rate was the main significant interaction. Thus, an erosive wear model was developed in terms of main factors and their significant interactions. The validity of the model was evaluated by conducting experiments under different wear conditions. A comparison of modelled and experimental results showed 5–11 per cent error. The modified (La2O3 addition) HVOF-sprayed coating showed high erosive wear resistance compared to unmodified coating. This is due to the increase in hardness of the modified coating.
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