二甲基二乙氧基硅烷对TEOS凝胶化过程的影响

以TEOS溶胶凝胶过程的动态激光光散射研究为基础,在过程的不同阶段加入二官能团有机硅单体DDS。用SEM分析产物的不同形貌。结果表明,DDS的加入对TEOS凝胶化过程产生了较大的影响,所得相分离产物随着DDS加入时间的不同呈现出一定的规律。这种规律的出现与动态激光光散射的研究结果达到了统一,从宏观上进一步体现了TEOS溶胶凝胶过程的特征,对在活性二氧化硅表面键接复合其它单体的研究必将起着重要的指导作用。     

聚碳酸脂板材高温力学拉伸性能实验的研究

阐述了对聚碳酸酯(PC)板材进行的高温力学拉伸实验的结果,获得了该材料在100℃～130℃范围内的一些力学性能参数。实验数据表明:PC板料并不是在所有高温区都具有良好的塑性指标。同时给出了PC板材一些力学性能指标随温度或拉伸位移速度变化而变化的规律。     

高温耐热合金Nimonic 80A锻造工艺探讨

船舶、坦克用柴油机的排气阀主要采用Nimonic 80A锻制而成.Nimonic 80A具有很高的耐热性能,在高温下强度高,变形抗力大,增加了锻造成形的难度.本文通过研究试验,提出了一套切实可行的胎模锻造成形方法.     

Agglomerate control in the complexing sol-gel process

lINTR0DUCTIONClassifiedinterms0fformationmechanismsofsolandgel,thesol-gelprocessincludesthreetypes:conventionalcolloidalsol-gel,inorganicpolymericsol-gel(i.e.,hydrolysisofmetalalkoxides),andcomplexingsoLgel['J.Fortheinorganicpolymericsol-gelpr0cess,differenceofhydroIysisrateamongdifferentalkoxidesusuallyleadst0poorhomogeneity,sooneproblemwiththisprocessisthehighercostasaresultofex-pensivechemicalsandinconvenientpreparation...diti...[2].Thisproblemcanbesolvedbyus-ingthec0mplexingsol-gelpro…     

串联法生产氧化铝的试验研究

结合实验探讨串联法生产氧化铝的配料、烧结、溶出、沉降等各工序的工艺技术指标，并针对出现的问题提出了解决途径。     

模具充型过程中光滑粒子流体动力学模拟(英文)

讨论了基于光滑粒子流体动力学(SPH)的压铸充型模拟的实施过程。建立了一种区分流体粒子和入流粒子的入流边界条件。对人工黏度和移动最小二乘法在处理压力振荡中的作用进行了对比。对最终模型在模拟压铸二维与三维的充型过程进行了验证。将SPH和有限差分的模拟结果与实验结果进行了对比研究。结果显示SPH与实验更为吻合,表明了SPH在描述充型过程流态方面的有效性与精度。     

Mechanism of scaling on oxidation reactor wall in TiO2 synthesis by chloride process

1 Introduction Titania particles are synthesized by the gas-phase oxidation of titanium tetrachloride in a high temperature tubular flow reactor on a large industrial scale. This so-called chloride process has been reported by several researchers[1?5]. In…     

镍基变形高温合金在高温环境下的氧化行为(英文)

研究了617和Haynes230高温合金在含H2O和O2的不纯氦气、含氢的热蒸汽、空气以及纯氦气中的900℃氧化行为。与空气相比,氦气、含氢的热蒸汽对617合金的氧化速率没有明显影响,而Haynes230合金在氦气中表现出较慢的氧化速率。617合金的氧化层形貌和结构受环境的影响明显,而Haynes230受环境的影响不明显。在所有的氧化环境中,Haynes230合金的氧化层都包含有中间层Cr2O3和外保护层MnCr2O4,这使其具有较好的抗氧化性能。合金的表面抗氧化性能明显影响其力学性能,如蠕变和拉伸性能。因此,有必要采取表面处理来增强合金的抗氧化性能。     

Optimization of Partial Melting Process for Bi-2212 Multi-Filament Wires

采用共沉淀工艺制备Bi-2212前驱体粉末,并结合粉末装管法得到19×(36+1)的Bi-22212多芯线材。在部分熔化热处理过程中分别对最高热处理温度Tmax和冷却速率Rc1进行了优化。使用扫描电子显微镜对线材中第二相的分布和芯丝状态进行观察。同时,通过对线材进行差热和热重等热分析方法,对线材在热处理过程中的气孔和第二相的形成过程进行定量分析。结果发现,最高热处理温度和冷却速率对芯丝中包括Bi-2201和AEC等在内的第二相种类和含量,及气孔密度都有较大影响。最终获得最优化的热处理工艺为Tmax=892℃,并且冷却过程采用Rc1=40℃/h的两步降温法,在77 K自场条件下得到了4400 A·cm-2的临界电流密度,本研究为进一步提高Bi-2212线材熔化热处理过程优化提供了理论依据。     

高温预处理及等温淬火工艺对CADI力学性能的影响

研究了高温预处理、奥氏体化温度(Tγ)及等温淬火温度(TA)对0.5%Cr含碳化物等温淬火球墨铸铁(CADI)的韧性、硬度的影响。结果表明,高温预处理可使CADI的冲击性能提高90%以上。当硬度为51.4~55.7 HRC时,冲击吸收能量(K)可达37.7~18.3 J。高温预处理后,随着Tγ的升高,CADI的K明显提高,硬度在一定范围内略有降低;随着TA的升高,CADI硬度逐渐降低,而K在260 ℃时达到最高。     

A self-tuning ultrasonic sensor based powder injection molding process

Ultrasonic sensors show great promise in defect detection and classification when monitoring the powder injection molding (PIM) manufacturing process. To date, however, these sensors are not used in a closed-loop control system. A simplex method is developed that automatically tunes a manufacturing system operating conditions on the basis of in situ ultrasonic sensor readings. Potential applications for this system include the initial set-up of optimal manufacturing conditions and also tracking of the optimum conditions in situ during long-term operation.     

高温高碱"双流法"溶出的工业应用与实践

通过选矿拜耳法的主要工序--高温双流法的工业实施及试生产运行情况介绍,对高温双流法工业实践中出现的问题,如:碱液预热器泄漏及预热器结疤等进行分析并寻找出初步解决办法,通过分析影响选精矿溶出性能的诸多因素,寻找出优化生产技术指标的途径,为进一步提高高温双流法的运行质量提供借鉴.     

供应链企业中基于BPR的定制ERP解决方案研究

本文研究供应链企业中基于BPR的定制ERP解决方案。首先通过对现代制造企业实施供应链管理的思索 ,分析了ERP和BPR在供应链管理中发挥的重要作用 ;并以一个典型的制造企业为背景 ,提出了一个基于BPR的定制ERP解决方案 ,为企业进一步实施供应链管理以及电子商务奠定了良好的基础     

A new method to cope with decision makers' uncertainty in the equipment selection process

One of the main problems faced while configuring or reconfiguring manufacturing systems is to rank alternative designs taking into account all the different aspects involved (both tangible and intangible). For this purpose the Analytic Hierarchy Process (AHP) is a well-known decision making support method that addresses this problem. A major drawback of AHP is that uncertainty in the judgments of the decision makers and the resulting impact on the ranking is not considered. In real situations, however, judgments based on perceived future scenarios are almost always uncertain. To solve this problem in this paper we present the first complete probabilistic extension to the AHP method. The new method provides the decision maker not only with information on the ranking of the alternatives but also the probability that the ranking remains stable even in presence of uncertainty in the judgements. We verified the validity of the new method in a real application developed for the Ferrari racing team.     

碳热还原合成Ti(C,N)晶须的相转变行为及生长机理

以TiO2和碳黑为主要原料,NaCl为卤化剂,NiCl2作为晶须生长的添加剂,在N2气氛下采用碳热还原法,在不同温度下合成Ti（C,N）晶须。采用X射线衍射研究合成样品的相组成及合成过程中原料的相转变行为,采用扫描电镜观察合成样品的形貌,探讨晶须的生长机理并建立生长模型。结果表明：在1 200℃合成时,主要发生TiO2与碳黑、氮气之间的直接还原反应,形成TiN;在温度为1 250-1 400℃时,NaCl分解产生的Cl原子起卤化作用,从NiCl2中分解出的Ni起催化作用,合成出Ti（C,N）晶须,晶须长度在10-30μm之间,直径大约1μm;合成的晶须表面光滑,顶端残留有催化剂颗粒,具有典型的气-液-固晶须生长机制特征。     

A2W3O12（A=Y, Er, Ho, Yb）型稀土钨酸盐的高温XRD研究及结构精修

用高温固相反应法制备出A_2W_3O_(12) 型稀土钨酸盐材料(A=Y,Er,Ho,Yb),用室温及高温XRD测定其在不同温度下的结构、晶胞参数及晶胞体积,并用TOPSA软件对其结构进行精修.发现除HO_2W_3O_(12)外,都具有较大的负热膨胀系数.据A. W. Sleight预测,HO_2W_3O_(12)具有较大的负热膨胀特性,但本实验却发现它并没有负热膨胀性,反而具有非常大的正热膨胀系数.     

等离子-熔化极气体保护焊电弧特性研究现状

等离子-熔化极气体保护焊的电弧形态和熔滴过渡方式直接关系到焊缝质量,采用不同的电极连接形式,如直流正接、直流反接,电弧形态及熔滴过渡方式均不同;主要介绍了目前等离子-熔化极气体保护焊在采用不同的电极连接形式下,不同的电弧形态和熔滴过渡方式,以及电弧成分组成和温度分布;通过对熔化极等离子弧静特性等方面的研究发现,熔化极电流的大小不是由焊丝与工件间的电压决定的,而是由导电嘴与焊丝端部处的等离子弧电位差决定的,并决定电流的方向.     

A three-dimensional study of flow in the fullering process using an elastic-plastic finite-element simulation

This paper describes research work concerned with the three-dimensional finite-element simulation of the fullering process. The main objectives of this preliminary study are to provide the details of metal flow during the process in order to investigate the effects of various parameters, to examine the correlation between the finite-element results and those of empirical relationships and to evaluate some aspects of empirical methods of fuller die design for a typical forging component. The activities carried out to achieve these objectives are explained in this paper.     

Synthesis mechanism of titanium carbide nano-fiber during self-propagating high temperature synthesis

Titanium carbide nano-fiber was synthesized by self-propagating high temperature synthesis (SHS) method. The final products after the SHS reaction were titanium carbide containing excess carbon and metallic titanium, which were removed by additional leaching process. TEM observation revealed that the average diameter is about 20 nm. Neutron diffraction analysis was carried out to study non-stoichiometric number of the titanium carbide. The non-stoichiometric numbers of the titanium carbide were 0.89–0.94. The Rietveld refinement of each patterns converged to good agreement (÷2=0.49–1.34). The formation mechanism of the carbide is related to a liquid-solid reaction including the preferential diffusion process of carbon atom into liquid titanium. This article is based on a presentation made in the 2002 Korea-US symposium on the “Phase Transformations of Nano-Materials,” organized as a special program of the 2002 Annual Meeting of the Korean Institute of Metals and Materials, held at Yonsei University, Seoul, Korea on October 25–26, 2002.     

高温退火二次升温阶段的工艺参数对HiB钢底层形成的影响

研究了高温退火二次升温阶段的退火温度及露点温度对HiB取向硅钢表面硅酸镁底层的影响。结果表明,高温退火二次升温阶段的最终温度在1100~1170 ℃范围内时生成的硅酸镁底层质量较好;当退火气氛中存在水蒸气时,会降低硅酸镁底层的质量,且水蒸气含量越高,即露点温度越高,硅酸镁底层的厚度越薄,质量越差。