Reaction behavior and wear properties of in-situ air plasma-sprayed Al2O3-TiB2 composite coatings

In this study, Al2O3-TiB2 coating was successfully deposited on steel substrates by in situ plasma spraying (IPS) using H3BO3, Al, and TiO2 reactants. Beside TiB2 and Al2O3, Al18B4O33 was formed as a by-product with ratio of about 13 wt%. The effect of milling time of reactant and the reaction behavior was also explored. Milling process for at least 10 h can promote efficiency of reaction and milling for efficient production of Al2O3-TiB2 composite. Wear behavior was examined in terms of hardness, wear track width, and wear rate of the coatings with respective measured values of 797.6 HV, 1061.3 & mu;m, and 4.2 x 10-3 mm3/N.m. Based on the FESEM observations, the thickness of abrasive coating was 417 & mu;m, delamination and adhesion were the main wear mechanisms in Al2O3-TiB2-coated specimens.