共查询到20条相似文献,搜索用时 187 毫秒
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TiB2材料具有高熔点、高硬度、耐磨、耐腐蚀、抗氧化以及导电性好和导热性好等优点,是一种具有广泛应用前景的新型陶瓷材料.但是其极强的共价键晶体结构和较低的自扩散系数,使得其很难获得致密的陶瓷材料.主要从添加助烧剂和烧结技术两方面介绍了TiB2陶瓷活化烧结方法的研究进展,并分析了该技术促进材料烧结致密化的机制,同时介绍了热压烧结和放电等离子(SPS)烧结技术. 相似文献
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研究分别采用了放电等离子烧结方法(Spark Plasma Sintering,SPS)和普通烧结方法,对(Ba,Sr)TiO3陶瓷进行不同温度下的烧结(1200~1300℃),进而研究了放电等离子烧结对(Ba,Sr)TiO3陶瓷性质的改良能力.实验表明,同温度下SPS法烧结的(Ba,Sr)TiO3陶瓷具有更大的相对介电常数,更低的电流损耗.同时,从SEM照片中观测到SPS烧结法可以较好的改进陶瓷的表面致密度.另外,1240℃下用SPS方法烧结的(Ba,Sr)TiO3陶瓷有着最优良的性质. 相似文献
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庞前涛 《中国材料科技与设备》2008,5(3):45-47
本文主要介绍了一种粉末烧结技术——放电等离子烧结。首先从结构设计上进行了介绍,放电等离子烧结的主要原理是在粉末进行压力烧结的同时施加电流,最终实现材料的致密化。放电等离子烧结的主要优点是烧结温度低、时间短、升温快、材料致密等。最后列举了放电等离子烧结技术在热电材料、硬质材料、功能梯度材料等的应用实例,论述表明放电等离子烧结技术是一种可以制备高性能材料的烧结技术。 相似文献
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放电等离子烧结(SPS)YAG陶瓷的初步研究 总被引:2,自引:0,他引:2
研究了采用放电等离子烧结(Spark Plasma Sintering SPS),利用高纯的氧化钇和氧化铝,在1500~1700℃,真空度优于10Pa,反应快速合成YAG陶瓷,但试样的致密度不高,而低气孔率是制备透明陶瓷的关键,实验表明,TEOS的掺加和粉料粒度的减小对烧结试样致密度的提高有一定的作用. 相似文献
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放电等离子烧结制备透明AlN陶瓷 总被引:3,自引:3,他引:0
采用放电等离子烧结(spark plasma sintering,SPS)技术,添加不同含量CaF2为烧结助剂,成功制备了透明氮化铝(AlN)陶瓷.SPS技术具有烧结快速,烧结体致密度高的特点,是制备透明AlN的有效方法.CaF2的加入量的提高,有利于烧结体的致密度和透过率的提高.当CaF2加入量为3%(质量分数)时,烧结体致密度不再继续提高,但仍有利于透过率的提高,此时烧结体透过率最高为54.7%.SEM、XRD、TEM和EDX结果表明烧结体具有很高的致密度、纯度,均匀的晶粒形状和尺寸,晶界及三角晶界处观察不到第二相的存在,从而保证了烧结体良好的光学性能. 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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Steffen Müller-Probandt 《材料科学与工程:中英文B版...》2018,(4):161-177
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di... 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Janet Lang 《Materials and Manufacturing Processes》2017,32(7-8):857-866
ABSTRACTThe production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them. 相似文献
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Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ... 相似文献