Formation mechanism of the TiN containing coating on the Al2O3-Ti2O3 composite at 1400?C nitrogen-blowing

The Al2O3-Ti2O3 composite is a byproduct of smelting ferrotitanium alloy, and a gold coating material was successfully obtained by nitriding this raw material at 1400 degrees C for 3h. The material was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, thermal gravimetry and differ-ential scanning calorimetry (TG-DSC) and vibrating sample magnetometry (VSM). The formation of TiN con-taining coating layer on the surface of the material was confirmed by XRD and Raman spectroscopy analysis. The golden surface disappeared after polishing by cross-section polishing, and the titanium compounds in the ma-terial after nitriding showed a gradient distribution from the surface to the inside as TiN -> Ti3O5 -> Ti2O3. From SEM analysis, titanium nitride was observed to be obtained by a gas-solid reaction with cluster growth, and the thickness of titanium nitride was approximately 10 mu m. The main reaction in the nitridation process was determined by TG-DSC as well as thermodynamic analysis. The sample maintained a uniform mass increase from 665 degrees C to 1430 degrees C, and the Ti2O3 on the surface of the sample underwent both nitridation and oxidation. The hysteresis of the sample as a composite was complex before nitriding, and behaved as a soft magnetic material after nitriding, indicating the macroscopic scale coating uniformity of the samples.