溶胶-凝胶法制备超细Mo-Cu粉末及性能表征

Preparation of Mo-Cu superfine powder by sol-gel process and characterization of powder property

以七钼酸铵和硝酸铜为原料通过溶胶-凝胶法制备Cu含量（质量分数）为20％的超细Mo-Cu复合粉末，再在1050-1200℃下烧结粉末压坯制得Mo-Cu复合材料；通过热重分析（DTA-TG）、X-ray衍射分析（XRD）和透射电镜（TEM）等分别对干凝胶煅烧前后的粉体以及还原后所得Mo-Cu复合粉末进行表征，通过扫描电镜观察Mo-Cu烧结体的显微组织，并对其密度、物理和力学性能进行测定，探索制备高致密、高性能Mo-Cu复合材料新工艺。结果表明：通过溶胶-凝胶法可以制得平均粒度为150nm、组成均匀的Mo-Cu超细粉末，该粉末具有良好的烧结性能，其成形压坯在1200℃下于H2气氛中烧结90min后，相对密度可达99.78％，烧结体的抗弯强度和维氏硬度分别为988MPa和HV227，电导率和导热系数分别为42.56％IACS和157W／（m·K），室温至450℃的热膨胀系数在6.7×10^-6－7.6×10^-6K^-1之间。

Mo-20%Cu （mass fraction） superfine powder was synthesized by a sol-gel method, in which sols was formed and transformed to gels by heating a complex solution containing ammonium heptamolybdate, copper nitrate and aqueous ammonia. The gels were then calcined and hydrogen-reduced to convert into Mo-Cu powder. Phase constitution and morphology of the gel, the calcined powder, as well as the resulting Mo-Cu powder were characterized by X-ray diffraction analysis（XRD） and transmission electron microscopy（TEM）. Density of the sintered Mo-Cu parts was measured by the Archimedes method. Microstructure of the sintered Mo-Cu compact was observed by scanning electron microscopy（SEM）. It was shown that the sol-gel process produces superfine Mo-Cu powder with particle size of about 150 nm. The Mo-Cu powder shows good sinterability. Relative density of 99.78% of the theoretical value is achieved for Mo-Cu powder compacts sintered at 1200℃ in H2 atmosphere for 90min. Furthermore, the sintered Mo-Cu compact exhibit excellent physical and mechanical properties. Electrical conductivity and thermal conductivity of the Mo-Cu compact sintered at 1200℃ are 42.56% IACS and 157 W/（m·K）, respectively. Bending strength and Vickers hardness are 988 MPa and HV 227, respectively. Thermal expansion coefficient is between 6.7×10^-6-7.6×10^-6K^-1 from room temperature to 450℃.