关键词： 气门座   显微结构   耐热钢   性能  

摘要： 研究了Fe-18.2Cr-6.9Ni-2.5Mo-1.5C(wt%)铸态组织及时效过程中的相转变,并对其硬度、耐磨性、高温硬度、抗氧化性和线膨胀系数进行了测定。结果表明其性能达到了SAEJ-610bNo10合金水平,能够满足 CA141型载重汽车汽油发动机排气门座性能要求。

关键词： 镁橄榄石   镁质耐火材料   显微结构  

摘要： 以锆英砂和电熔镁砂为原料，合成ＺｒＯ_２增韧的镁橄榄石材料，进而加入 鳞片状石墨，得到Ｍｇ_２ＳｉＯ_４／Ｃ（－ＺｒＯ_２）－Ｃ复合材料。用扫描电镜、Ｘ射线衍射仪、 差热、红外光谱等手段研究了该材料的显微结构和矿物组成。表明该材料具 有优异的高温强度、抗侵蚀性和热震稳定性，是一种新型耐火材料。

摘要： An attempt has been made to understand wear-induced subsurface microstructural changes and material removal mechanisms in squeeze-cast BS LM11 alloy dispersed with 10 vol % SiC. Particles as well as fibres of SiC were separately dispersed in the alloy matrix to determine the influence of shape of the dispersoid on the abrasion behaviour of the latter. Abrasion tests were conducted on a standard rubber wheel abrasion test apparatus. Silica sand was used as the abrasive medium. Abrasive wear rates of the specimens were found to decrease gradually with the number of test intervals until a steady state value was attained. This was attributed to the protrusion of the reinforcement phase and abrasion-induced work hardening of the matrix in regions close to the abraded surface. The dispersoid/matrix interface as well as the shape of the dispersoid was found to influence the abrasion rate of the composites. A poor dispersoid/matrix interface led to higher rate of abrasion due to pull-out of the dispersoid. On the other hand, good bonding between the dispersoid and the matrix helped the dispersoid phase to be retained by the matrix, offering reduced rate of abrasion.

关键词： 耐火材料   氧化钠   含量   材料结构  

关键词： 压电陶瓷   断口   显微结构  

摘要： 对陶瓷材料进行的显微电镜断口分析表明:压电陶瓷材料断裂方式主要是溜晶断裂和解理断裂或者是两者的混合,且溜晶断裂优于解理断裂;应用Sol—Gel方法制备的陶瓷材料其显微结构好,宏观性能优越。

摘要： Site investigations of several concrete and masonry structures in Gothenburg, Sweden, revealed carbonation to have affected a number of concrete structures. At times, synergistic freeze-thaw action was found to have accelerated the deterioration process. Some of the masonry structures have developed internal and external efflorescence (the latter much more severe) in the form of alkali sulphate salts. The mechanisms involved in these processes and the influence of microclimatic conditions are discussed. The products formed that were mainly investigated by microstructural techniques (SEM with energy-dispersive X-ray analysis, X-ray diffraction analysis) are also described.

关键词： AlN陶瓷   原位生长   纤维状多型体  

摘要： 本文采用AlN-Y_2O_3-SiO_2,系制备出原位生长纤维状AlN多型体陶瓷复合材料,对其显微结构和生长机制进行了观察和研究,并测量其力学性能.实验结果表明,AlN-Y_2O_2-SiO_2系陶瓷复合材料的抗弯强度和断裂韧性较AlN陶瓷均有大幅度的提高,微观结构观察发现基体中存在大量共生的纤维状AlN多型体(27R,21R),系统中Y_2O_3不仅是原位生长复合AlN材料的致密剂,而且是纤维状多型体生长的媒介,SiO_2,是纤维状多型体生长的助生长剂,基体内纤维状多形体的存在提高了AlN陶瓷的强度和韧性。

关键词： SiC   晶须   陶瓷基   复合材料   韧化  

摘要： 通过XRD、SEM、TEM及EPMA技术研究了Al_2O_3-25vol％ZrO_3(2mol％Y_3O_3)-25vol％SiCw(AZS)三元陶瓷复合材料的显微组织和力学性能。试验结果表明,该材料具有较好的强度和韧性配合,ZrO_2与SiC晶须同时起增韧作用。此外,SiC晶须以及弥散分布在Al_2O_3基体中的ZrO_2粒子也提高了该材料的断裂强度。室温下测得该材料的压痕断裂韧性为10.8MPam^(1/2),抗弯强度为676MPa。

关键词： 碳纤维增强   铝基   复合材料   界面  

摘要： 界面在金属基复合材料中起着极为重要的作用.在碳纤维增强铝基复合材料中纤维及其表面涂层与基体的相互作用(特别在高温时),一方面能提供纤维与基体之间的粘接,而有效地传递载荷;另一方面,过度的反应将改变碳/铝复合材料的破坏模式而严重影响性能.界面反应产物的多少及形状与纤维的种类、基体的成分、工艺方法及热处理温度等有关.