Micro-abrasion wear behavior of thermal-spray-coated steel tooth drill bits

Wear behavior of four kinds of thermally sprayed coatings on steel tooth drill bits have been investigated by micro-abrasion wear test. The fixed ball micro abrasion wear test was applied for bare substrate and for thermal sprayed substrate of each sample. SiC and Al₂O₃ abrasive powders with grain size of 5 μm were used in the abrasion experiments. Ball rotational speed values of 140 rpm and applied loads of 1, 2 and 3 N were used. Experimental results show that the wear mechanisms of the coatings are micro-grooving and micro-rolling. Application of the coatings was found to have an influence on the wear mechanism of the samples. The results also indicate that wear resistance of thermally sprayed coatings can be correlated to porosity, hardness, plasticity, toughness, and cohesion properties of the coatings. In addition, wear resistance of the coated samples had increased in accordance with the increasing coating thickness.