Evaluation of performance of WC-CoCr coatings with HVOF and hard chrome for application in clay mixing machine

Due to the abrasive characteristic of the clay used in the manufacture of bricks, tiles, and structural blocks, the blades of mixers suffer severe abrasive wear, which results in low mixing efficiency and low-quality products. These blades are made of nodular cast iron, a low-hardness alloy. The growing demand from the ceramic industry for lower costs and higher productivity are among the main reasons for improving the performance of these mixers. Therefore, this work aims to evaluate the performance of metallic coatings, manufactured by electrodeposited hard chromium and by the thermal spraying process - type High-Velocity Oxy-Fuel (HVOF), using the WC-CoCr alloy. In this research, it was evaluated the resistance to abrasive wear of the coatings, by the standard test ASTM G65 and of industrial application. Although the WC alloy has the highest hardness compared to hard chromium, the chromium coating showed the lowest wear coefficient, 6,490 x 10^-5, and 7,680 x 10^-5 for the WC-CoCr alloy. With the study, it was realized the feasibility of application only of hard chromium, due to the cost of the tungsten carbide alloy. (author)