γ-AlOOH nanopowder synthesized using hydrothermal-assisted freeze-drying was employed as a precursor, with AlF₃ as a sintering aid, to explore the preparation of α-Al₂O₃ with a high specific surface area at elevated temperatures. The γ-AlOOH nanopowder produced in this study exhibited superior dispersion, achieving a specific surface area of 198.06 m 2 /g and a zeta potential of 45.8 mV. At a calcination temperature of 1200 °C, the resulting α-Al₂O₃, synthesized from γ-AlOOH and AlF₃, maintained a specific surface area of 27.72 m 2 /g, significantly higher than the typical values reported in the literature (generally below 10 m 2 /g). The α-phase purity exceeded 99 %, and the [AlO₆] proportion was 95.07 %. Furthermore, at a calcination temperature of 1150 °C, the specific surface area of the α-Al₂O₃ reached 50.48 m 2 /g. Using this α-Al₂O₃ as a carrier, a composite TiO₂ catalyst was prepared via a sol-gel and hydrothermal method. This catalyst demonstrated a photocatalytic degradation rate of over 98 % for rhodamine B (10 mg/L) within 30 min of irradiation, under the illumination of a 300 W mercury lamp in proximity to the light source.
Sun Qin,Yang Wanchun,Hu Zhongyu,Jia Gaozhi,Wang Yangyang
Copper pastes are widely used in metallization of ceramic surfaces but are limited by poor oxidation resistance, high resistivity, and low bonding strength. In this work, the 30Bi 2 O 3 –55B 2 O 3 –15ZnO glass powder was prepared by the melt-quenching method. A copper paste containing the glass powder and formic acid-treated copper microparticles was used for metallization of α -Al 2 O 3 ceramic surface. The copper thick films were obtained by low-temperature sintering after screen printing. The effects of the glass powder contents on resistivities and shear strengths of the copper films on α -Al 2 O 3 ceramic substrate were analyzed. The microstructures of the copper thick films and the interfacial bonding mechanism on the α -Al 2 O 3 ceramic surface were investigated in detail. The copper thick film with 10-wt% 30Bi 2 O 3 –55B 2 O 3 –15ZnO glass and sintered at 650 °C for 20 min exhibited a low resistivity (3.38 ± 0.94 µΩ cm) and a high shear strength (35.24 ± 1.2 MPa). ZnAl 2 O 4 and Bi 2 B 4 O 9 were detected on the edges of the copper film near the interface, which enhanced interfacial binding between the copper thick films and the α -Al 2 O 3 ceramic substrate. These results demonstrated that the low-temperature sintering copper paste containing 30Bi 2 O 3 –55B 2 O 3 –15ZnO glass was effective for α -Al 2 O 3 ceramic surface metallization.
危险品化学品经营许可证（带存储）