陶瓷球磨机研磨体对筒体作用载荷分析与计算

基于球磨机研磨体运动的散体理论,对陶瓷球磨机研磨体的运动形态进行了分析,并着重计算了工作状态时研磨体对筒体作用的载荷,确定了载荷作用区间,得出了载荷沿筒体截面的区间分布函数。分布函数可以用于对球磨机进行应力应变分析的有限元方法之中施加边界条件。     

喷雾造粒技术在反应烧结SiC密封材料中的应用研究

研究了水基料浆喷雾造粒粉体在反应烧结SiC密封材料中的应用.通过对均匀、稳定分散的水基SiC C料浆进行喷雾干燥,制备的反应烧结碳化硅复合粉体与传统工艺相比流动性能得到明显改善,适用于连续自动干压成型,并且避免了传统工艺的热压成型.采用新工艺制备出密度为3.10 g/cm3,游离硅含量为8.22Wt%,硬度(HRA)90,抗折强度为434MPa的碳化硅密封材料,主要性能高于传统工艺和行业标准,可以与国外同类产品技术指标相比.     

奥氏体不锈钢搪玻璃反应釜的研制和应用

用奥氏体不锈钢作为搪玻璃反应釜的受压元件基体和设计的专用底釉 ,经特定的搪烧工艺方法制成在一定的低温工况 (≥ - 40℃～≤ - 2 0℃ )下能安全运行的不锈钢搪玻璃反应釜。该设备的推广应用对促进我国生物工程、医药化工、有机高分子等行业的发展起到积极作用。     

Quantitative measurement of repetitive impact damage on ground silicon nitride surfaces

Structural ceramics are finding application in automotive and truck engines. Poppet valves and valve seats, for example, require resistance to surface damage from repetitive impacts. Grinding and finishing processes can leave microcracks or residual stresses in the surfaces of ceramics which can accelerate surface-initiated degradation processes. A ball-on-inclined plane, repetitive impact testing system has been developed to study the effects of finishing method on surface durability. Tests were performed by repeatedly striking ground alumina and silicon nitride flat specimens with a silicon nitride sphere and measuring the impact damage as a function of the number of strikes. One type of alumina and three types of silicon nitride ceramics were tested. A quantitative impact damage parameter (IDP), based on mechanical stylus profiling data, was developed for use in measuring small amounts of wear. When damage did not extend beyond the depth of valleys in the machined surfaces, the IDP exhibited an excellent linear correlation with the number of impacts of silicon nitride on both silicon nitride and alumina materials. When more extensive damage occurred, a method involving digitizing the area of the contact damage from photomicrographs provided a reasonable correlation with number of impacts. These two methods are compared. Scanning electron microscopy revealed features which can affect the accuracy of impact damage measurement. Implications of the technique are discussed.     

Wear of single crystal silicon as a function of surface roughness

With increasing activities on micro electro-mechanical systems (MEMS) type microactuators, there is a growing need in understanding the tribological properties of silicon, the most commonly used wafer material for those devices. In particular, it is of interest if single crystal silicon used in microactuators exposed to rather low vertical loads is subject to wear. Therefore, wear tests using monocrystalline silicon on both sides of the tribological interface were conducted.A classic way to measure wear on sliders in contact with a tape or a rotating disk is to create an imprint using a Berkovich diamond tip mounted on a picoindenter. However, in our case we used a different approach. We created three studs on a slider’s surface by recessing the material outside the studs through an ion milling process. During the wear tests, the studs wore off. By measuring the remaining stud height, the wear volume could be determined at any point in time. The tests were performed on a pin on disk tester with a gimbaled slider to realize a flat on flat contact and a rather low normal force of 30 mN.     

氮化硅陶瓷刀具的切削性能及其应用

阐述了氮化硅陶瓷刀具的切削性能及其在实际应用中应该注意的问题 ,为在机械加工行业中推广应用陶瓷刀具作了初步的探讨     

Si3 N4浸渍处理提高硬度的研究

用硅粉冷等静压成型和反应烧结氮化工艺制造的氮化硅样品不规则气孔且多大，硬度偏低。浸渍处理可以填充气孔，显著提高硬度和抗弯强度。     

多晶硅微机械零件的制作及测试

探讨利用硅表面微细加工工艺制造微型机械的方法，制作了微涡轮，微传动齿轮，微螺旋弹簧和微凸轮传动机构等微机械结构，实现了齿轮的啮合传动，微弹簧扭转及微凸轮传动机构的运动。对多晶硅材料的机械物理性能，微机械系统动力学特性进行了测试分析。     

陶瓷增强相对金属-陶瓷复合涂层的影响

对电弧喷涂几种不同陶瓷增强相的Fe复合涂层的特点和性能进行了研究，在20钢基体上喷涂含陶瓷TiB2／Al2O3，TiB2-Cr3C2，TiB2，Cr3C2及TiB2-Cr3C2-Al2O3的管状喷涂丝材，采用光学显微镜和XRD对涂层的微观特性进行分析，结果表明，涂层中含有TiB2，Al2O3，Cr3C2，Cr3O2等陶瓷相。通过对涂层常规性能测试表明，含TiB2／Al2O3和Cr3C2的涂层孔隙率较低、结合强度高、并具有优良的耐磨性及抗热震性能。     

Atmospheric effects of friction,friction noise and wear with silicon and diamond. Part II. SEM tribometry of silicon in vacuum and hydrogen

Scanning electron microscope (SEM) tribometric data on polycrystalline silicon (poly-Si) vs. poly-Si, Si(100) vs. Si(100) and Si(111) vs. Si(111) interfaces, obtained in Torr and in 0.2 Torr partial pressure of hydrogen gas ( ) from room temperature to 850^°C, were performed under standard and much slower thermal ramping rates. The friction data were analyzed per the methodology described in part I of this paper series. The results indicate a highly beneficial friction- and wear-reducing regime within a relatively narrow thermal region. This desirable region coincides with some chemisorption of excited species of molecular hydrogen just before the mass thermal desorption of surface hydrides. These data represent the tribochemical equivalent of a method routinely used in electronics, whereby deep electron traps (dangling Si bonds) are passivated by baking in molecular hydrogen. The also exerts a moderating influence on the size of the friction noise at all test temperatures. However, the general level of friction beyond the beneficial thermal region is high. In parallel, the general wear rate of Si representative of the entire range of standard thermal ramping in both atmospheric environments is in the extremely high 10^-12m³/(N m) range. Operating strictly in the beneficial, low-friction thermal regime resulted in a several orders-of-magnitude reduction in the wear rate over those measured under standard thermal ramping conditions. Although the results confirm previous findings that Si is not a good material of construction for miniaturized moving mechanical assemblies (e.g., microbearings and gears), there seems to be some limited possibility of gas-phase lubrication of Si micromechanisms with rarefied hydrogen at surface temperatures between 100 and 300^°C. This revised version was published online in July 2006 with corrections to the Cover Date.