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纳米W−30Cu−La2O3粉末的制备及烧结性能

Preparation and sintering properties of nanometer W−30Cu−La2O3 powders

  • 摘要: 以钨酸、硝酸铜、六水硝酸镧为原料,甘氨酸为燃料,硝酸铵为助燃剂,采用低温自蔓燃法制备前驱体粉末,经氢气还原获得纳米W–30Cu–La2O3复合粉末,在氢气气氛烧结制备W–30Cu–La2O3合金。研究了钨酸与甘氨酸、硝酸铵的摩尔比对前驱体粉末和还原复合粉末物相、形貌和性能的影响。分析了不同烧结温度下W–30Cu–La2O3合金的相对密度、微观组织和综合性能。结果表明,钨酸与甘氨酸、硝酸铵的摩尔比分别为1:10、1:25时,粉末均匀性好,比表面积为6.6271 m2·g−1,粉末尺寸为100~200 nm。1350 ℃为最佳烧结温度,在1350 ℃烧结制备的合金相对密度、抗弯强度、维氏硬度和热膨胀系数分别为99.0%、1205 MPa、HV 307和9.17×10−6 K−1,组织细小均匀,断裂方式为韧性断裂。

     

    Abstract: Tungsten copper oxide precursor powders were prepared by low temperature self-propagation method with tungstic acid, copper nitrate, and cerium nitrate hexahydrate as the raw materials, glycine as the fuel, ammonium nitrate as the accelerant. Nanometer W–30Cu–La2O3 composite powders were obtained by hydrogen reduction, and the W–30Cu–La2O3 alloys were prepared by sintering in hydrogen atmosphere. The effects of molar ratios of tungstate with glycine and ammonium nitrate on phase, morphology, and properties of the precursor powders and the reduced composite powders were investigated. The relative density, microstructure, and comprehensive properties of the W–30Cu–La2O3 alloys at different sintering temperatures were analyzed. The results show that the optimal molar ratio of tungstic acid with glycine and ammonium nitrate is 1:10 and 1:25, respectively. The powders have good uniformity, the specific surface area is 6.6271 m2·g−1, and the powder size is 100~200 nm. The optimal sintering temperature is 1350 ℃. The relative density, bending strength, Vickers hardness, and thermal expansion coefficient of the alloys sintered at 1350 ℃ is 99.0%, 1205 MPa, HV 307, and 9.17×10−6 K−1, respectively. The microstructure is fine and uniform, and the fracture morphology is ductile fracture.

     

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