OBJECTIVEIn this work, we aim to determine the optimum pH value for the preparation of 3% yttria-stabilized tetragonal zirconia polycrystalline (3Y-TZP)/3%Al₂O₃ and optimum calcination temperature of Al₂O₃ precursor and amorphous boron nitride (BN) for Al₂O₃-BN coating 3Y-TZP powders.

METHODSThe 3Y-TZP/3%Al₂O₃ composite powders were prepared through the heterogeneous precipitation method under different pH values (6.5, 7.5, 8.5, and 9.5) and analyzed through transmission electron microscopy (TEM) to determine the optimum coating morphology. Al₂O₃ precursor, which was prepared under the optimum pH value, was calcined at different temperatures (800, 1 000, 1 200, and 1 400 ℃). The amorphous BN coating 3Y-TZP/3%Al₂O₃ powder was prepared via in situ reaction with boric acid and urea (calcined with N₂ at 850 ℃ for 5 and 3 h and 800 ℃ for 5 and 3 h). TEM, energy dispersive spectrometry (EDS), and X-ray diffraction (XRD) were performed to characterize the results.

RESULTSThe optimum coating morphology was obtained at 8.5 pH. When the Al₂O₃ precursor was calcined at 1 200 ℃ and coated with BN (calcined with N₂ at 800 ℃ for 5 h), the Al-B-O compound was less, and t-ZrO₂ was more represented.

CONCLUSIONSThe optimum pH value for 3Y-TZP/3%Al₂O₃ composite preparation is 8.5. For the preparation of Al₂O₃-BN coating 3Y-TZP powders, the optimum calcination temperature of the Al₂O₃ precursor and amorphous BN are 1 200 and 800 ℃, respectively.