Oxidation kinetics of overstoichiometric TiB2 thin films grown by DC magnetron sputtering

We systematically study the oxidation properties of sputter-deposited TiB2.5 coatings up to 700 C. Oxide-scale thickness dox increases linearly with time ta for 300, 400, 500, and 700 C, while an oxidation-protective behavior occurs with dox = 250 & BULL;t0.2a at 600 C. Oxide-layer's structure changes from amorphous to rutile/ anatase-TiO2 at temperatures & GE; 500 C. Abnormally low oxidation rate at 600 C is attributed to a highly dense columnar TiO2-sublayer growing near oxide/film interface with a top-amorphous thin layer, suppressing oxygen diffusion. A model is proposed to explain the oxide-scale evolution at 600 C. Decreasing heating rate to 1.0 C/ min plays a noticeable role in the TiB2.5 oxidation.

Automated summary

We studied the oxidation properties of sputter-deposited TiB2.5 coatings at different temperatures. The results showed that at 600 degrees Celsius, the coating exhibited protective oxidation behavior, and the structure of the oxide layer also changed. Moreover, decreasing the heating rate had a noticeable impact on the oxidation process.