THE WEAR PERFORMANCES OF FINE GRAINED ALUMINA BALLS

The wear performance of fine grain alumina ball adding diopside as fluxing agent are reported for the first time in this paper. The ball (average grain size 3 mum) exhibits excellent toughness and low wear rates. Ploughing grooves and traces of micro-cutting occur at the place with no pore. And the wear process is mainly caused by plastic deformation mechanism. Yet, the ordinary alumina balls (average grain size 6 and 15 mum) are brittle and the wear rates are high. The intergranular and transgranular dropping pits occur, and the wear process in mainly caused by brittle fracture mechanism.

Enhanced removal of ultra fi ne particles from kerosene combustion using a dielectric barrier discharge reactor packed with porous alumina balls

Ultrafine particles(UFPs)are harmful to human beings,and their effective removal from the environment is an urgent necessity.In this study,a dielectric barrier discharge(DBD)reactor packed with porous alumina(PA)balls driven by a pulse power supply was developed to remove the UFPs(ranging from 20 to 100 nm)from the exhaust gases of kerosene combustion.Five types of DBD reactors were established to evaluate the effect of plasma catalysis on the removal efficiency of UFPs.The influences of gasflow rate,peak voltage and pulse frequency of different reactors on UFPs removal were investigated.It was found that a high total UFP removal of 91.4%can be achieved in the DBD reactor entirely packed with PA balls.The results can be attributed to the enhanced charge effect of the UFPs with PA balls in the discharge space.The UFP removals by diffusion deposition and electrostatic attraction were further calculated,indicating that particle charging is vital to achieve high removal efficiency for UFPs.

Preparation of Alumina Abrasion-Resistant Ceramic Grinding Ball with Spent FCC Equilibrium Catalyst

化学作文，结构和从一个炼油厂的花的 FCC 平衡催化剂的热稳定性被 XRD，英尺红外， DTA-TG，赌注，完全的化学分析， SEM，和 XRF 描绘。花的 FCC 平衡催化剂，泥土，钡碳酸盐，和滑石被用作主要原料准备氧化铝在为建筑学瓦的制造磨工厂的粉末要过去常的磨损抵抗的陶器的球。结果证明在合适的明确的表达学习以后，花的 FCC 平衡催化剂能代替工业氧化铝准备磨球的高效。同时，磨擦的球的各种各样的表演索引能为类似的产品满足优秀标准，并且另外，节省效果的精力在磨擦的节的操作被完成，导致稳固的浪费的成功的全面利用。

Preparation of High Performance Grccn Alumina Ceramic Balls by Roller Production Waste

To reuse roller waste as a raw material of high performance green ceramic balls, three kinds of white alumina ceramic balls whose wear resistance were 2-3 times of the best high alumina ceramic ball with 90% Al2O3 were prepared, and the Al2O3 content of the prepared balls was 75%. It is found that the effect of calcia and magnesia on the wear resistance of ceramic balls is contrast to the accepted one： the wear rate of the ceramic balls prepared in CaO-Al2O3-SiO2 system is the lowest and the wear rate of the ceramic balls prepared in MgO-Al2O3-SiO2 is the highest. The main crystal phase of the ceramic ball is mullite and corundum. The ceramic ball granular is uniform and fine with 4-5 μm average size. The pore diameter is about 2 μm. The wear way of the ceramic balls is mainly transcrystalline fracture.

德兴铜矿KLM-75型立磨机磨矿介质试验研究与应用

德兴铜矿尾矿回收厂为改善二段磨矿效果,针对原ϕ0.9m×1.8m卧式溢流型球磨机存在的磨矿效果差、磨矿效率偏低的问题,采用KLM-75型立磨机取代原卧式球磨机,并对该立磨机的磨矿条件进行了试验研究。试验结果表明:以氧化铝陶瓷球作为KLM-75型立磨机的磨矿介质时,磨矿效果最好,检查分级溢流细度提高了3.75个百分点,立磨机运行电流下降了13.66%,磨矿介质日耗降低了94.73%,螺旋衬板使用周期提高了136.84%,节能效果显著。

Solvent-free synthesis of alumina supported cobalt catalysts for Fischer–Tropsch synthesis

A novel mechano-synthesis method has been elaborated in this work for the design of efficient cobalt-based Fischer–Tropsch catalysts. The process aims to reduce the total number of steps involved in the synthesis of solid catalysts and thus to avoid relevant toxic solutions generated during the catalyst preparation. The mechano-synthesis of the Co/Al2O3catalyst was processed in a low-energy vibratory micro mill and high energy planetary ball mill. Porous spherical γ-aluminas (1860 µm and 71 µm mean particle diameter) were used in this work as host compounds. Co3O4(3 µm mean particle diameter) has provided guest particles for mechano-synthesis. The catalysts were characterized by textural (surface area, porosity and particle size) and structural analyses (X-ray diffraction, TPR, SEM-EDX and microprobe). The microprobe images show deposition of Co3O4on the surface of the alumina and indicated no Co3O4diffusion inside the alumina pores. SEM-EDX mapping illustrated that cobalt coating tended to occur on surface of rounded shape of cracked alumina fragments. After milling, the crystallite size of Co3O4decreased to 15 nm from 30 to 50 nm. The TPR profiles indicated very low concentrations of inactive cobalt aluminate mixed compounds which are usually produced during the catalyst preparation by impregnation. In Fischer–Tropsch synthesis, the catalysts prepared using mechano-synthesis methods showed catalytic performance comparable to the catalysts prepared by impregnation. © 2016 Science Press

Grinding Characteristic of Multi-walled Carbon Nanotubes-alumina Composite Particle

The synthesis of new materials containing multi-walled carbon nanotubes （MWCNTs） and the microstructure of alumina particles were investigated and characterized. The MWCNTs and alumina particles were ground under both the dry and wet conditions with various rotation speeds （200 - 400 r/min） in planetary ball milling machine, and their combination characteristics were described. The experimental results were examined by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, transmission electron microscopy （TEM） and particle sizing analysis （PSA）. SEM result revealed that the combination of MWCNTs - Alumina particles mixed quite well under both the dry and wet grinding with rotation speed of 400 r/rain. XRD characterization indicated the better result could get in ground samples at a rotation speed of 400 r/min. PSA result showed the particle size decreased with increase the grinding speeds. From the overall results, we observed that the grinding method can be used to synthesize new material with high efficiency.

Synthesis of Nano-Size AlN Powders by Carbothermal Reduction from Plasma-Assisted Ball Milling Precursor

Nano-size aluminum nitride （A1N） powders have been successfully synthesized with a high efficiency method through annealing from milling assisted by discharge plasma （p-milling） alumina （Al2O3） precursors. The characterization of the p-milling Al2O3 powders and the synthesized AlN are investigated. Compared to conventional ball milling （c-milling）, it can be found that the precursors by p-milling have a finer grain size with a higher specific surface area, which lead to a faster reaction efficiency and higher conversion to A1N at lower temperatures. The activation energy of p-milling Al2O3 is found to be 371.5 kJ/mol, a value that is much less than the reported value of the unmilled and the conventional milled Al2O3. Meanwhile, the synthesized AlN powders have unique features, such as an irregular lamp-like morphology with uniform particle distribution and fine average particle size. The results are attributed to the unique synergistic effect of p-milling, which is the effect of deformation, fracture, and cold welding of Al2O3 powders resulting from ball milling, that will be enhanced due to the introduction of discharge plasma.

球磨法对氧化铝镀银材料导电性能的影响

使用球磨法对氧化铝镀银材料进行改性,最佳的工艺为:氧化铝与玛瑙球的重量比为20%,球磨频率为5.5 Hz,球磨时间为3 h,最高导电率为1887 S/cm,比未球磨的提高37倍。通过红外光谱仪、X射线衍射仪、热失重仪、偏光显微镜和悬浮测试了氧化铝镀银材料的性能,结果表明:球磨对氧化铝红外光谱没有影响,镀银后氧化铝的红外吸收振动峰消失;X射线衍射证明氧化铝镀银材料中有银的晶体峰出现,没有其它杂质峰;热失重表明镀银材料的残留变大,耐热性能提高;偏光显微镜显示球磨后氧化铝为片型结构,大小分布均匀;镀银材料悬浮溶液颜色较深,能够悬浮于乙醇溶液中,有望提高在高分子复合材料中的分散性能。最后阐述了球磨使得氧化铝大颗粒被破碎以及颗粒被磨削这两种作用,形成片,增加了表面积和包银效率,提高了颗粒之间导电网络的连接,使得导电率变大的机理。该导电材料期望在电磁屏蔽、导电胶粘剂和抗菌复合材料等诸多领域都有广泛的应用前景。

氧化铝球在泗洲选矿厂二段磨矿中的应用

为降低泗洲选矿厂二段磨矿作业球磨介质消耗和磨矿电耗,针对传统磨矿介质钢球在磨矿过程中自身消耗和磨矿电耗高的缺点,进行了氧化铝瓷球替代钢球试验研究。通过试验室不同球径氧化铝球配比试验和生产现场磨矿介质充填率对比试验,得出35,25 mm 2种球径按质量比6∶4,磨矿介质充填率为36%时,磨矿产品中的-0.074 mm含量最高,磨矿过程最稳定。分析钢球和氧化铝球生产运用对比试验数据可知,氧化铝球可使磨机磨矿电单耗下降约30%,介质单耗下降66%,经济效益显著,具有推广价值。

超声冷冻干燥混粉工艺对WC-6Co-GO/Al_(2)O_(3)硬质合金组织及性能的影响

分别采用机械球磨法和球磨−超声−冷冻干燥法制备WC-6Co-GO/Al_(2)O_(3)混合粉末,并通过冷压成形−烧结制备块体硬质合金,研究混粉工艺和GO/Al_(2)O_(3)复合粒子含量对混合粉末的分散性以及合金的微观形貌、致密度和力学性能的影响。结果表明:超声−冷冻干燥可以有效地解决GO/Al_(2)O_(3)复合粒子的团聚问题,获得细小均匀的粉末颗粒。采用球磨−超声−冷冻干燥法混粉时,所制备的GO/Al_(2)O_(3)复合粒子质量分数为0.15%的硬质合金中,复合粒子均匀分布在WC晶粒间使细化晶粒的效果较显著,而且合金的相对密度较高,合金的强度提高至2723.6 MPa,比普通机械球磨的合金提高约600 MPa,硬度(HV30)和断裂韧性分别提高约200.0和1.0 MPa·m^(1/2)。

碳纳米管和氧化铝混杂增强铝基复合材料的制备及力学性能

采用化学气相沉积结合机械球磨的方法制备了碳纳米管(CNTs)和Al_2O_3颗粒混杂增强铝基复合材料,研究了球磨时间、Al_2O_3含量对复合材料组织和力学性能的影响。结果表明:本方法可以获得CNTs和Al_2O_3颗粒在铝基体内的均匀分散。随球磨时间的增加,复合材料的硬度随之增大;当球磨时间为180min时,复合材料硬度达纯铝的2.1倍。此外,随Al_2O_3颗粒含量的增加,复合材料的硬度和压缩屈服强度均不断提高。当Al_2O_3的质量分数为4%时,CNTsAl_2O_3/Al复合材料的硬度达112.1HV,为纯铝的2.8倍;压缩屈服强度达416MPa,为纯铝的4.6倍,说明CNTs和Al_2O_3的混杂加入发挥了良好的协同增强效果。

氧化铝高能球磨时机械力化学效应研究

研究了氧化铝在高能球磨过程中机械力化学效应的变化 .机械力化学效应因子随球磨时间的变化可分为三个阶段 :第一阶段主要是晶粒尺寸减小和显微应变增加同时进行 ;第二阶段主要是有效温度系数的增加 ;第三阶段主要是点阵膨胀至饱和 .用溶解法比较了球磨前后氧化铝的活性 ,发现经球磨后 ,氧化铝在盐酸中的溶解活化能由 18kJ/mol降至 4kJ/mol,表面活化层增厚 .

透辉石助烧剂对氧化铝瓷球显微结构和耐磨性的影响

研究了透辉石 (CaMgSi2 O6 )助烧剂对 90 %氧化铝瓷球显微结构和耐磨性的影响 .透辉石助烧剂的引入 ,使瓷球具有均匀细小的晶粒 ,从而获得了强化和增韧 ,提高了瓷球的耐磨性 .氧化铝瓷球的磨损机理主要是穿晶断裂的塑性微观切削 .瓷球的晶粒尺寸、密度、抗压强度、磨损率分别为 :1.5～ 4μm ,3 .62g·cm- 3,2 0 80MPa,0 .2 5 %·h-

氧化铝粉体湿法球磨参数优化

为获取可用于陶瓷膜支撑体烧结的、粒径分布合理的原料粉体,实验中以粒径500 M的氧化铝粉体为原料,探索其湿法球磨最优条件。在不同球磨时间和球料比条件下进行球磨,对比球磨效果,测定球磨后粉体的粒径及分布并综合考虑成本因素后得出结论。实验结果表明,球料比(9～11)∶1、球磨时间9～10 h为最优球磨条件。后续实验则表明,在最优球磨参数下所得粉体粒径较均一,可直接用于烧结耐高温、高强度的陶瓷膜支撑体。

等离子体复合微量贵金属催化反应器催化氧化苯的机理分析

苯排放到大气中会影响空气质量和人体健康,其排放需要得到控制。为此,利用装有微量贵金属(Au、Ag和Pt,负载量(质量分数)0.1×10–6~10×10–6)催化剂的介质阻挡放电(DBD)反应器分解模拟空气中的苯,研究了苯在不同贵金属负载量、不同反应温度和不同能量密度条件下的分解特性,并对苯的分解机理做了探讨。实验结果表明:1)和无催化剂的DBD反应器相比,载有贵金属催化剂的DBD反应器能显著增加苯的去除率。2)在反应温度为25℃和能量密度为400 J/L的条件下,各催化剂对苯的最大去除率按从高到低排序为:Au(93.8%)>Pt(81.1%)>Ag(81.0%)>无催化剂(55%)。3)苯分解的气相产物为CO和CO2,在催化剂负载量和反应温度一定的条件下,苯的去除率随能量密度的增加而增加。4)在催化剂负载量、能量密度一定的条件下,苯的去除率随反应温度的增加而增加。

工艺条件对用辊棒废料制备的中铝瓷球显微结构及性能的影响

以辊棒废料为主要原料,在CaO-MgO-SiO2-Al2O3体系中,研究烧结温度、保温时间、成型方式和压力大小对中铝瓷球显微结构及性能的影响规律及其机理。结果表明:在150MPa等静压成型,1330oC烧结,保温3h的工艺条件下,研制含铝量小于60%的中铝瓷球的性能最优异,磨损率为0.0503%/h,密度为3.1062g/cm3,与市售90瓷球相比,磨损率与之持平,白度与市售90瓷球不相上下。

工艺参数对α-Al_2O_3粉体性能的影响

以440℃预烧后的AlOOH或无定形Al2O3为原料,乙醇为分散剂,采用机械球磨和常压焙烧法制备α-Al2O3粉体,探讨矿化剂AlF3及机械球磨对α-Al2O3性能的影响,利用扫描电镜、X射线衍射、X射线圆盘式离心粒度分析仪等手段对α-Al2O3粉体分散性、颗粒形貌和物相进行表征。结果表明,焙烧后得到纯α-Al2O3相粉体,且随着AlF3用量的增加,α-Al2O3粉体的分散性变差,α-Al2O3的形貌由多维向二维转化,从而形成片状α-Al2O3;由于机械力化学及F-的作用,球磨4 h出现六方片状α-Al2O3,且随着球磨时间的延长,六方片状α-Al2O3数量增多,粒径增大。

球磨氧化铝晶粒尺寸与显微应变的关系

研究了高能球磨氧化铝的晶粒尺寸和显微应变发现球磨后氧化铝的显微应变（ε） 与晶粒尺寸（ Ｄ） 符合逆变关系， 即晶粒尺寸越小， 显微应变越大显微应变与晶粒尺寸的倒数成线性关系， 在ε～１ Ｄ 图上出现双斜率表明球磨不同阶段，

高能球磨制备立方AlN及其高温相变

研究了高能球磨过程中Al2O3的相变,随着球磨时间的延长,粉末中发生了γ-Al2O3向α—Al2O3的转变．高能球磨20h,Al2O3部分非晶化,同时,有立方AIN生成．增加球磨强度,立方AIN生成量增加,650r／min高能球磨40h,AlN生成量达到72％．随后的氮气气氛退火实验发现,在500℃以上,立方氮化铝与氧化铝反应,生成AlON相．AlON相的生成,有效地降低了碳热还原氮化反应激活能．