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以添加20%质量分数Al粉作为粘结剂的Al-TiO2-B2O3系粉末为原料,在Ar保护气中进行机械球磨,通过扫描电镜(SEM)、能谱分析仪(EDS)、背散射电子探测仪(BSED)分析混合粉末在机械球磨中粉末粒度、结构特征的演变过程,测试了不同球磨时间混合粉末的XRD图谱和DTA曲线。研究结果表明:在球磨40 h过程中,Al-TiO2-B2O3混合粉末由晶态颗粒转变为非晶态颗粒,经历了团聚一粉碎一均匀分布一非晶化一系列演变过程,形成细小复合颗粒;颗粒尺寸变化在球磨过程中是由小到大,再到小的冷焊-破碎过程,球磨8 h前混合颗粒冷焊占主导因素,并于8 h时长到最大(200μm),8 h后混合颗粒以硬化破碎占主导因素,并制得超细粉末颗粒;差热分析(DTA)测试不同球磨时间粉末样,其燃烧反应临界温度随球磨时间的延长而下降,当球磨超过16 h时,从未球磨时的700~1000℃下降并稳定在560℃左右,反应形式转化为瞬间、剧烈、充分的方式,并在X射线衍射物相分析(XRD)检测出燃烧反应伴随反应生成球磨过程没有产生Al2O3-TiB2硬质相,这种新生弥散Al2O3-TiB2硬质相在熔融Al液中分布。
The Al-TiO2-B2O3 powder with 20% mass fraction Al powder as binder was mechanically ball milled in Ar shield gas and characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), backscattered electron Detector (BSED) was used to analyze the evolution of powder particle size and structure characteristics in mechanical ball milling. The XRD patterns and DTA curves of mixed powders with different ball milling time were tested. The results show that during the milling process of 40 h, the Al-TiO2-B2O3 mixed powder changes from crystalline particles to amorphous particles and undergoes a series of evolution processes from reunion to comminution to formation of fine composite particles . The change of particle size during ball milling was from small to large, and then to the small cold welding-crushing process. The cold welding of mixed particles before ball milling for 8 h accounted for the dominant factor and reached the maximum (200 μm) at 8 h. After 8 h When the milling time is longer than 16 h, the critical temperature of the combustion reaction decreases with the milling time prolonging, It never changes from 700 ℃ to 1000 ℃ and stabilizes at around 560 ℃. The reaction mode transforms into an instantaneous, vigorous and sufficient mode. The combustion reaction accompanied with the reaction was not observed by X-ray diffraction (XRD) Produced Al2O3-TiB2 hard phase, the freshly dispersed Al2O3-TiB2 hard phase in the molten Al liquid distribution.