(中南大学 粉末冶金国家重点实验室,长沙 410083)
摘 要: 采用溶胶−喷雾干燥法制备不同铜含量的W-Cu前驱体粉末,前驱体粉末分别在400、600和800 ℃各煅烧90 min,运用XRD和SEM等手段对煅烧前后复合粉末的相组成和显微形貌进行分析,研究前驱体粉末在煅烧过程中的相变行为。结果表明:前驱体粉末在煅烧过程中发生一系列的分解和化合反应,随着煅烧温度的升高,粉末的相组成、颗粒形貌和尺寸发生明显变化,对W-30%Cu(质量分数)合金,在400 ℃煅烧后,复合粉末由WO3、CuO和CuWO4组成,粉末颗粒大多呈立方结构,大小为200~400 nm;在600 ℃煅烧后,复合粉末由CuO和CuWO4组成,粉末颗粒大多呈短棒状结构,大小为400~500 nm;在800 ℃煅烧后,复合粉末由CuO、CuWO4和Cu3WO6组成,粉末颗粒大小为3~4 μm;前驱体粉末中铜含量对煅烧后复合粉末的相组成也存在较大影响,铜含量越多,越容易生成复合氧化物。
关键字: W-Cu;CuWO4;Cu3WO6;高温煅烧;相变;溶胶−喷雾干燥
(State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China)
Abstract:W-Cu precursor powders with different copper contents were fabricated by sol-spray drying. Precursor powders were calcined at 400, 600 and 800 ℃ for 90 min, respectively. Phases and microstructure of pre-calcined and post-calcined powders were investigated by XRD and SEM in order to study the phase transformation of precursor powders. The results show that precursor powders undertake a series of decomposing and compounding reactions during calcining. With the increasing of calcining temperature, the phases, morphology as well as particle size of the powder change obviously. For W-30%Cu (mass fraction) composite powder, the composite powder is composed of WO3, CuO and CuWO4 after calcining at 400 ℃ and the particles exhibit cubic shape with sizes of 200−400 nm. The powder after calcining at 600 ℃ consists of CuO and CuWO4 and the particles are mostly of rod-like shape of 400−500 nm in size. The powder after calcining at 800 ℃ is composed of CuO, CuWO4 and Cu3WO6 phases and the particles are 3−4 μm in size. The copper content in the precursor powder greatly influence the phase composition of the calcined powders. The increase of copper content facilitates the formation of composite oxide.
Key words: W-Cu; CuWO4; Cu3WO6; high temperature calcine; phase transformation; sol-spray drying