Sintering of Mullite–Zirconia Composite Powder Prepared by Ultrasonic Spray Pyrolysis Technique
Tóm tắt
Sinterabilities of mullite (3Al2O3·2SiO2–zirconia (ZrO2)composite powders prepared by ultrasonic spray pyrolysis techniques (USPTs) were examined. Starting mullite powders containing ∼18.5 mol% (∼15.0 vol%) of zirconia (ZrO2) were prepared by single-nozzle (SN) and double-nozzle (DN) USPT. In SN-USPT, the composite powder was prepared by spray pyrolysis of a water–ethanol solution in an Al(NO3)3–Si(OC2H5)4–ZrOCl2–YCl3 system at 900°C, using one ultrasonic vibrator. In DN-USPT, the composite powder was prepared by simultaneous spray pyrolyses of a water–ethanol solution in an Al(NO3)3–Si(OC2H5)4 system and one in a ZrOCl2–YCl3 system at 900°C, using two ultrasonic vibrators. When these composite compacts were fired at a temperature between 1400 and 1700°C for 5 h, the relative densities attained maxima, i.e., 87.2% (SN-USPT) and 95.5% (DN-USPT), at the firing temperature of 1500°C. Densification of the DN-USPT-derived powder compact proceeded more markedly than that of the SN-USPT-derived powder compact.
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