Synthesis and characterisation of a submicrometre silicon carbide powder

A beta-silicon carbide powder with a surface area of 30m²g^?l and a mean particle size of < 1μm was produced from the thermal conversion of silicon resin in an atmosphere of hydrogen. The amount of product increased with increasing iron content (0–2.1 wt%) and firing temperature (1200–1500°C). Chemical analysis, X-ray diffraction and i.r. absorption spectrometry were used to follow the conversion reaction.     

超细氧化锌粉体的制备及尺寸控制

根据气相化学反应法 (CAD)制备超细粉的原理 ,从低品位氧化锌矿中采用火法冶金方法直接制备超细氧化锌粉 ,对所得氧化锌的粒度尺寸、微观结构和粒度分布进行测试 ;考察了冷却强度以及收集装置对超细氧化锌粒度及粒度分布的影响 ;讨论了氧化锌粉体团聚的原因及对策、试验条件对氧化锌尺寸的控制等     

土壤固化剂无侧限抗压强度试验研究

针对山西省长治市石子河河道处理问题 ,采用固化剂粘土进行了无侧限抗压强度试验 ,并与水泥土进行了比较。发现固化剂 2的无侧限抗压试验强度最佳 ,为工地现场试验及河道综合治理提供了更为有力的理论依据     

复方SOD奶粉的研究

介绍了复方SOD奶粉的配方成分、设计依据、工艺流程，同时进行了该配方的动物喂养试验，即①小鼠急性毒性试验；②果蝇生存试验；③抗氧化功能试验；④免疫调节作用试验；并对其抗衰老、提高机体免疫力的功能特性进行了讨论。结果表明，复方SOD奶粉除了适合大多数人群外，尤其适合中老年人与脑力、体力疲劳过度者。     

水平浓缩燃烧器在65t/h煤粉炉上的应用

介绍65t/h煤粉炉的基本概况和存在的问题，详细阐述了采用水平浓缩煤粉燃烧技术对原燃烧器的改造过程，对改造前后运行参数及经济效益进行了对比。     

Thermoplastic elastomeric composition based on maleic anhydride–grafted ground rubber tire

Ground rubber tire (GRT) powder was maleated in an internal mixer using maleic anhydride and dicumyl peroxide at 160°C. Maleated GRT was characterized by using X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, wettability, and differential scanning calorimetry. The physical properties of the dynamically vulcanized 60 : 40, rubber : plastic composition based on acrylated high‐density polyethylene as the plastic phase and ethylene propylene diene rubber containing maleated GRT as the rubber phase were found to be greater than the corresponding composition containing nonmaleated GRT. The blend was found to be reprocessable, like themoplastic elastomers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 370–378, 2002; DOI 10.1002/app.10348     

Influence of melt superheat on breakup process of close-coupled gas atomization

In close-coupled gas atomization（CCGA）, the influences of melt superheat on breakup process are fundamental to obtain desired or finer powder. Based on a series of Cu atomization experiment under different superheating conditions, the influences of melt superheat on breakup process were studied. Experimental results indicate that as the melt superheat is increased to 150, 200, 250 and 300 K, the mean particle size （D50） decreases consequently to 34.9, 32.3, 30.9 and 19.7 μm. Theoretical analysis reveals that the primary breakup and secondary breakup processes are close coupled, and the melt superheat radically influences the melt properties, and plays a crucial role on governing the filming process of primary breakup and the atomization modes of secondary breakup. There exists a strong nonlinear decrease of contact angle of melt to nozzle orifice wall when the superheat is increased fi＇om 250 K to 300 K, leading to a marked fall of the film thickness formed in primary breakup, and D50 of copper powders is therefore sharply reduced. However, the log-normal distribution feature of particle size has not been substantially improved.     

莫来石材料的研究现状及其应用

较详细地介绍了莫来石的性能、生产、研究现状和用途。尤其对多元复合莫来石韧性陶瓷及莫来石超细粉末的制备进行了评述,同时展望了莫来石作为高级陶瓷材料的发展前景。     

Rolling contact fatigue behavior of sintered and hardened steels

Powder-metal-processed bearings and gears are finding increasing application because of their economical and technical advantages. The residual pores from the sintering operatives act as lubricant pockets and dampen sound and vibration. However, porosity also decreases the mechanical strength and reduces the life of components fabricated by powder processing relative to similar wrought components. The rolling contact fatigue behavior of sintered and heat treated steel rollers was investigated using a fatigue test machine designed and fabricated for that purpose. The powder-metal-processed and the wrought steel rollers that were tested had similar composition and hardness and were mated against wrought steel rollers of high hardness. The contact stress versus number of cycles to failure data showed that the wrought steel had a very high endurance limit under rolling contact fatigue compared to the sintered steels investigated. Rolling contact fatigue behavior was found to depend on the porosity present in the material. Large surface peeling failures and pitting type fatigue failures were observed in the sintered and hardened steels, while only pitting type failures were observed in the wrought steels     

钼还原过程相变化研究

采用钼酸铵直接氢还原及钼酸铵先焙解然后再分段氢还原两种不同的还原方法进行了钼粉还原。通过Ｘ射线衍射方法分析了两种工艺还原过程中的反应序列及相变化规律，并讨论了不稳定相Ｍｏ４Ｏ１１对于钼粉还原过程的影响。