溶胶-凝胶+机械球磨法制备纳米α-Al2O3/Ni复合粉体

摘要

Nano α-Al2O3/Ni composite powder was prepared by means of sol-gel plus mechanical ball milling method,its microstructure and structure evolution and morphology evolution in the process of ball milling were investigated and its refinement mechanism with ball milling was explored.The result showed that α-Al2 O3/Ni composite powders with integral crystalline structure could be obtained by using the composite colloid prepared with sol-gel method after calcining at 1 200 ℃ for 2 h and the microstructure of the composite powder would be core-shell spheric structure with a coverage of brittle nano α-Al2 O3 particles on the surface of Ni particle.In the mechanical ball milling process,the particle shape of α-Al2O3/Ni composite powder would experience a transformation from sphericity to flake to near-sphericity.When the ball milling time was 20 h,the refining effect of composite powder would be the best.The size of two-phase grain would be refined quickly at the beginning of ball milling.The average grain size of nano α-Al2 O3 would be reduced to 27 nm quickly after 5 h milling,and partial non-crystallization would appear when the ball milling time was 20 h.The grain size of Ni would reduce to 22 nm and 17 nm after 5 h and 10 h milling respectively and then tend to stable after 10 h milling.The super distributed system of α-Al2 O3 inside the Ni particles could be obtained from the composite powder prepared after milling for 20 h.%采用溶胶-凝胶+机械球磨法制备了纳米α-Al2O3/Ni复合粉体,研究了α-Al2O3/Ni复合粉体的微观结构及其在球磨过程中的结构演变和形貌演变,探讨了复合粉体的球磨细化机理.结果表明:通过溶胶-凝胶法制备的复合胶体经1 200℃煅烧2h后可获得晶体结构完整的-Al2O3/Ni复合粉体,粉体微观结构为脆性α-Al2O3纳米颗粒包覆于Ni颗粒表面的壳核型球形结构.在机械球磨过程中,αrAl2O3/Ni复合粉体的颗粒形貌经历了由球状到层片状再到类球状的变化,球磨20 h时复合粉体的细化效果最佳.2种物相的晶粒尺寸在球磨初期细化速率很快,纳米晶a-Al2O3在球磨5 h时平均晶粒尺寸迅速减小为27 nm,球磨20 h后出现部分非晶化;Ni晶粒尺寸则在5、10 h时减小至22、17nm,球磨10 h以后晶粒尺寸趋于稳定.复合粉体经球磨20 h后可获得α-Al2 O3弥散分布于Ni颗粒中的超级分散体系.