高能球磨合成纳米碳包覆α-Al2O3复合粉体

Nanocarbon-coated α-Al_2O_3 Composite Powders Synthesized by High-energy Ball Milling

以膨胀石墨和α-Al2O3微粉为原料,采用高能球磨制备了纳米碳包覆的α-Al2O3复合粉体,研究了高能球磨时间和球磨速率对复合粉体物相及形貌的影响。采用X射线衍射仪、场发射扫描电子显微镜和透射电子显微镜对复合粉体的物相、形貌和微观结构进行了表征。结果表明:按膨胀石墨与α-Al2O3质量百分比为1:2,球磨速率为600 r/min,球磨5 h可得到被粒度为20～50 nm碳颗粒包覆的α-Al2O3复合粉体;随着球磨时间延长,石墨(002)晶面特征峰逐渐消失,膨胀石墨中纳米片层会随球磨时间延长不断剥离脱落,并逐渐龟裂成纳米碳颗粒;相同球磨时间下,提高球磨速率可以促进纳米碳颗粒形成,但超过一定速率后纳米碳颗粒粒度不再减少;480 r/min速率球磨5 h未形成纳米碳颗粒包覆复合粉体,600和700 r/min速率球磨5 h后复合粉体形貌基本一致。

Nanocarbon-coated u-A1203 composite powders were synthesized by high-energy ball milling using expanded graphite and ct-A1203 as raw materials. The effects of milling time and speed on phase composition and microstructure of the composite powders were investigated. X-ray diffraction （XRD）, field emission scanning electron microscope （FESEM） and transmission electron microscope （TEM） were employed to characterize the phase compo- sition, morphology and microstructure of the composite powders. The results show that nanocarbon with a size of 20-50 nm coated on the a-A1203 particles when the expanded graphite and a-A1203 with a weight ratio of 1：2 were milled for 5 h at a speed of 600 r/rain. By increasing the milling time, the （002） diffraction peak of graphite gradu- ally disappeared, and nano-graphite sheets desquamated from expanded graphite and then chaped to nanocarbon particles. Milling for the same time, higher milling speed was beneficial to synthesize nanocarbon particles, but when milling speed reached certain value, the size of nanocarbon cannot become smaller again. Nanocarbon-coated a-A1203 composite powders cannot be synthesized using a milling speed of 480 r/min even milled for 5 h. The morphology and microstructure of the composite powders were basically the same when the composite powders were milled at 600 and 700 r/min for 5 h.