ABSTRACT
OBJECTIVE: In 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. METHODS: The 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 â). 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 â for 5 and 3 h and 800 â for 5 and 3 h). TEM, energy dispersive spectrometry (EDS), and X-ray diffraction (XRD) were performed to characterize the results. RESULTS: The optimum coating morphology was obtained at 8.5 pH. When the Al2O3 precursor was calcined at 1 200 â and coated with BN (calcined with N2 at 800 â for 5 h), the Al-B-O compound was less, and t-ZrO2 was more represented. CONCLUSIONS: The 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 â, respectively.
