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金属陶瓷既保持了陶瓷材料优异特性,又具备金属材料优势,是一种重要的新型工程材料。本文利用球磨方法制备氧化铝-铝金属陶瓷材料复合粉体,并对其进行表征和研究其致密化性能,为制备高性能金属陶瓷材料提供参考。球磨时间大于3 h,氧化铝颗粒在铝粉的周围分布较为均匀。在50 r/min的球磨条件下,氧化铝颗粒在铝粉周边的分布比在75 r/min的球磨条件下氧化铝颗粒在铝粉周边的分布更均匀。随着铝粉含量增加,氧化铝在铝粉中的分布范围大,且更加均匀,并有少量的钉扎现象,复合粉体所制备金属陶瓷的烧结致密性较好,为制备高性能金属陶瓷提供参考。 相似文献
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应用热压技术制备了添加不同含量Cr3C2和(W,Ti)C的Al2O3/Cr3C2/(W,Ti)C复合陶瓷材料。利用光学显微镜、环境扫描电镜、透射电镜和能谱分析仪等对~203/30%Cr3C2、Al2O3/30%(W,Ti)C、Al2O3/20%Cr3C2/10%(W,Ti)C三种复合陶瓷材料的显微组织结构进行了观察分析。研究表明:同其它两种材料相比,Al2O3/20%Cr3C2/10%(W,Ti)C陶瓷复合材料组织细化均匀,有连续骨架结构生成。Cr3G和(W,Ti)C颗粒的共同加入有利于晶粒生长的制约,裂纹分枝与偏转、晶粒拔出、以及纳米相等等,有效提高了氧化铝陶瓷材料的力学性能。 相似文献
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《粉末冶金材料科学与工程》2019,(6)
在超细氧化铝粉体中分别添加微量MgO、复合添加MgO+Y_2O_3(MgO与Y_2O_3的质量比为1:1)以及复合添加Mg O+La2O3作为助烧剂,通过氢气烧结制备透明氧化铝陶瓷片,利用扫描电镜观察氧化铝陶瓷材料的形貌,用分光光度计测量陶瓷片的透光率,研究助烧剂种类以及复合助烧剂MgO+Y_2O_3的含量对透明氧化铝陶瓷透光率的影响。结果表明,添加微量稀土作为烧结助剂,可抑制晶粒长大,并减少陶瓷的气孔数量,提高氧化铝透明陶瓷的透光率。添加复合助烧剂MgO+Y_2O_3的陶瓷透光率明显高于添加单一助烧剂MgO的陶瓷透光率。添加(0.02%~0.05%)MgO+(0.02%~0.05%) Y_2O_3(质量分数)复合助烧剂时,得到总透光率为80%以上的透明氧化铝陶瓷。但加入过多烧结助剂时,气孔数量增多,导致氧化铝陶瓷的透光率降低。 相似文献
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以酚醛树脂为基体,通过添加聚四氟乙烯、六钛酸钾晶须、纳米氧化铝等材料进行改性;采用特殊工艺将铜合金与磷铜合金网复合,制得金属基体层;采用热压、固化工艺将上述酚醛树脂改性材料复合到金属基体上,制得工作层,获得具有金属塑料复合结构的水润滑轴承材料,并对该材料进行摩擦试验,研究其在水介质下的摩擦性能。结果表明:聚四氟乙烯添加量最大时,试样的摩擦因数最低;六钛酸钾晶须添加量最大时,磨损深度最小;而纳米氧化铝添加量最大时,摩擦因数最高且磨损深度最大;表明聚四氟乙烯和六钛酸钾晶须有利于提高酚醛树脂的摩擦学性能,而纳米氧化铝的添加会降低酚醛树脂的摩擦学性能。 相似文献
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《稀有金属》2004,28(4):766-766
由中科院上海硅酸盐研究所高濂研究员主持完成的———晶内型氧化物基纳米复相陶瓷的制备科学与性能研究 ,由于在纳米复相陶瓷的制备研究方面达到国际领先水平 ,最近荣获 2 0 0 3年上海市科学技术进步一等奖。课题组开创性地提出了陶瓷材料晶内型纳米增强增韧的新概念 ,首次采用原位包裹法合成高均匀性、高烧结活性的复合纳米陶瓷粉体 ,首创用放电等离子体烧结技术 (SPS)实现了陶瓷材料的超快速烧结 ,制备出了多种高性能晶内型氧化物基纳米复相陶瓷。其中 ,采用上述技术制备的SiC Al2 O3纳米复相陶瓷 ,其抗弯强度由基体材料的 35 0MPa提… 相似文献
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阐述了我国纳米氧化铝生产企业的整体情况、市场价格和市场容量等,对其市场状况进行深入分析,对我国纳米氧化铝的发展前景做出预测,提出促进纳米氧化铝发展的若干建议。 相似文献
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文章以二冶酒钢项目为研究对象,运用效益审计相关理论,确定其审计任务和目的,采用检查、询问、函证、监盘、计算、分析性复核等效益审计方法,对该项目预算收入的准确性、实际成本的完整性、资金到位的可靠性情况进行核实,找出项目经营中存在的问题,并有针对性地提出一系列的改进意见和建议。 相似文献
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The problem of defining satisfaction and the difficulties in distinguishing interests and satisfactions are indicated. "Aside from the final, consummatory activity, satisfaction cannot be identified in terms of activities, as can interests… . Because opinion items are not as stable as interest items, it is doubtful that they can be as useful as interest items in predicting future behavior." 5 characteristics of interests are that they: are acquired, are persistent, vary in intensity, function in acceptance-rejection behavior, are indicated in readiness to act. "Interest tests are diagnostic because no two persons have acquired the same lists of activities nor are the activities classified in the same manner as liked or disliked. Moreover, people engaged in an occupation have to a marked degree similar interests, and so people in one occupation can be differentiated from members of other occupations." Major topics are: job satisfaction and job success; opinion, attitude, interest, and satisfaction; measurement of motivation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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This paper addresses an alternative methodology to calculate fragility functions that considers multiple limit states parameters, such as combinations of response variables of accelerations and interstory drifts. Limit states are defined using a generalized multidimensional limit states function that allows considering dependencies among limit thresholds modeled as random variables in the calculation of fragility curves that are evaluated as function of the return period. A California hospital is used as example to illustrate the proposed approach for developing fragility curves. The study investigates the sensitivity of the proposed approach for evaluating fragility curves when uncertainties in limit states are considered. Influence of structural and response parameters, such as stiffness, damping, acceleration and displacement thresholds, ground motion input, and uncertainties in structural modeling, are also investigated. The proposed approach can be considered as an alternative approach for describing the vulnerable behavior of nonstructural components that are sensitive to multiple parameters such as displacements and accelerations (e.g., partition walls, piping systems, etc.). 相似文献
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LL Ronk 《Canadian Metallurgical Quarterly》1993,24(5):65-67
Traditional roles need not become self-fulfilling prophecies if managers can bridge the gender gap. Feminine, as well as masculine, characteristics can be incorporated into managerial styles to enhance effective leadership. Autonomy, decision-making and assertiveness are as important as nurturing and caring. What are little girls made of? Little girls are made of sugar and spice and everything nice. What are little boys made of? Little boys are made of rats and snails and puppy dog tails. 相似文献
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大剧院工程由于结构设计平面尺寸超长,结构楼层高低错落,体型多变,不宜设置结构缝;另外建筑结构设计空间大,设置了多层看台,中间设有超大升降舞台及乐池,导致结构本身自重大,跨度大,体积大,这就要求控制施工、使用阶段出现结构裂缝,因此在结构设计中采用了无粘结预应力及有粘结预应力技术,以改善钢筋混凝土结构的综合性能、承载能力及控制结构裂缝。 相似文献