液相烧结Al_2O_3/3Y–TZP复相材料的致密化与力学性能

以CaO–MgO–SiO2玻璃为烧结助剂,用液相烧结法制备了氧化铝和3%氧化钇稳定四方氧化锆复相材料。研究了烧结助剂对材料致密化、显微结构及力学性能的影响。结果表明:由于CaO–MgO–SiO2玻璃具有较小的液相粘度,因而对材料的致密化有较大促进作用,可使材料在1500℃获得致密。烧成温度和材料组成均对Al2O3和ZrO2的平均晶粒尺寸产生影响。显微结构中少量的Al2O3和ZrO2晶粒为晶内分布。引入烧结助剂降低了材料的烧结温度,使材料具有细晶结构,因而具有良好的力学性能,在最佳条件下,样品的抗弯强度可达到778MPa。     

少量掺杂Al2O3、SiO2的Mg-PSZ陶瓷材料的液相烧结

通过在Mg-PSZ陶瓷材料中少量掺杂Al2O3或SiO2,可使材料在较低温度(≤1550℃)下实现液相烧结,使材料的烧结温度大幅度降低.随Al2O3、SiO2掺杂量摩尔分数在1%～4%范围内增加,材料中m-ZrO2相组成增加,相应的烧结密度降低.所形成的镁铝尖晶石相多分布于ZrO2晶粒间,而形成的镁橄榄石相多镶嵌于ZrO2晶粒内.     

Al2O3微粉和SiO2微粉对刚玉-莫来石材料性能的影响

在板状刚玉细粉中添加粘土或Al2O3微粉和不同种类的SiO2微粉制成刚玉-莫来石试样,分别于1200℃、1400℃和1600℃保温5 h烧成后,测定试样的体积密度、显气孔率和烧后线收缩率,利用XRD分析了试样在不同温度段的莫来石生成量,研究了添加Al2O3微粉和不同种类的SiO2微粉对材料的烧结性能和莫来石化的影响,并利用SEM观察了试样的显微结构.结果表明(1)加入Al2O3微粉和SiO2微粉均有利于材料的烧结;加入SiO2微粉的纯度和晶形不同,对试样莫来石化的影响也不同,无定形态SiO2微粉(即硅灰)的纯度越高,试样的莫来石生成量也越高.(2)加粘土的试样,其显微结构中柱状莫来石的晶体特征比较明显;而加入SiO2微粉的试样,其莫来石晶体和刚玉晶体相互交错,晶粒较小.     

信息集锦

添加SiO2 ,CaO和MgO对Al2O3晶粒生长的影响 纯Al2O3在1620℃烧结,其正常晶粒生长形成各自同性的晶粒和曲面的晶界,当同时加入100ppm的SiO2和50ppm的CaO时,形成线性晶界部分,产生拉长的大晶粒,出现异常晶粒生长,研究表明添加SiO2或同时添加SiO2和CaO的Al2O3出现晶粒异常生长与形成多个平面状和线状晶界有关,这些晶界具有单一取向的结构,晶界能低,随后的晶界移动生长即导致晶粒的导常生长。而添加MgO可使晶界变粗糙,促使正常的晶粒生长,纯Al2O3的晶界也是粗糙的,因此,也是正常的晶粒生长。(周耀）洁具釉的硼酸盐助熔…     

添加MgO对不同SiO2含量的ZrO2-Al2O3-SiO2陶瓷烧结的影响

以高纯石英砂、α-Al2O3、ZrO2为原料,MgO为添加剂(添加质量分数分别为0、1%、2%、3%),经研磨、造粒、成型,并在1 600℃烧结2 h后获得了SiO2含量(w)分别为4%、8%、12%的ZrO2-Al2O3-SiO2系陶瓷试样。采用XRD、SEM对试样进行物相和显微结构的分析。结果表明:1)所制备的ZrO2-Al2O3-SiO2陶瓷的主要物相是单斜氧化锆、莫来石和刚玉,随着SiO2含量(w)由4%增加到12%,SiO2与Al2O3反应生成的莫来石量增加,体积膨胀效应越发明显,导致烧结试样的致密度降低;2)添加MgO促进了ZrO2-Al2O3-SiO2陶瓷的烧结,在SiO2含量为4%(w)的陶瓷中加入1%(w)的MgO时,烧结试样的致密度最大,其相对密度达到90.49%,体积密度为3.90 g·cm-3。     

氧化锆/氧化铝复相陶瓷显微组织缺陷分析

针对5Y-ZrO2/Al2O3复相陶瓷出现的晶粒异常长大和晶粒开裂问题展开研究。以ZrO2和Al2O3为主要原料,采用常压烧结工艺制备陶瓷样品,利用SEM观察显微组织。分析表明:MgO对抑制Al2O3晶粒异常长大有重要影响,MgO的加入量应随着Al2O3加入量的变化而改变;烧结温度的改变将导致异常长大的Al2O3晶粒细化。当烧结温度较低时,Al2O3晶粒将在短轴方向逐渐断开成段;当温度较高时,则沿着长轴方向逐渐开裂成条状。ZrO2晶粒的断裂主要与烧结温度有关:在1630℃以上烧结时,出现裂纹并贯穿晶粒;晶粒开裂的原因是:烧结温度较高时,陶瓷中形成了t-ZrO2,在降温过程中大颗粒的t相发生t→m相变,而小颗粒t相则无法变成m相,引起局部体积变化不均匀,从而产生相变应力导致晶粒穿晶断裂。     

ZrO2/Al2O3复相陶瓷的制备及性能研究

本文以工业用ZrO2和α-Al2O3微粉为原料,通过干压成型和常压烧结工艺制备ZrO2/Al2O3复相陶瓷.通过检测复相陶瓷的体积密度、显气孔率、常温抗折强度、烧后线变化率和热震稳定性,研究不同α-Al2O3微粉加入量及添加剂Y2O3对ZrO2/Al2O3复相陶瓷烧结性能、常温强度、热震稳定性及微观结构的影响,并通过SEM方法对烧后试样的微观结构进行表征.结果表明:系统配料中加入Al2O3会降低ZrO2/Al2O3复相陶瓷的致密度,常温强度随着Al2O3加入量增大而呈现先增大后减小趋势,然而热震稳定性有一定程度改善.Y2O3作为一种助烧剂可以促进ZrO2/Al2O3复相陶瓷结构内晶粒长大,加入Y2O3有利于增强复相陶瓷的烧结性.     

液相烧结氧化铝和氧化钇稳定四方氧化锆复相材料的显微结构与力学性能

以TiO2，MnO2及CaO—Al2O3-SiO2玻璃为烧结助剂，利用液相烧结法制备了氧化铝和3％氧化钇稳定四方氧化锆复相材料。研究了烧结助荆对材料致密化、显微结构及力学性能的影响。结果表明：除TiO2可与ZrO2晶粒形成部分固溶外，烧结助剂主要以晶间玻璃相的形式存在，并影响了Y2P3在ZrO2晶粒中的分布。烧结助荆的引入显著促进材料的致密化，降低了烧结温度，使材料具有细晶结构，因而具有良好的力学性能。     

ZrO2对Al2TiO5-板状刚玉复合材料性能的影响

以α-Al2O3微粉、板状刚玉和TiO2为主要原料,添加不同含量的ZrO2,通过高温烧成以固相反应直接合成Al2TiO5-板状刚玉-ZrO2复合材料,研究了ZrO2含量对复合材料的烧结收缩率、显气孔率、强度等的影响。结果表明:添加ZrO2的复相材料的收缩率和体积密度明显增加。ZrO2含量为4%时,可以制备出高致密度高强度的Al2TiO5-板状刚玉-ZrO2复合材料,其显气孔率为9.31%,抗折强度为25.6MPa,抗压强度为225MPa。     

MgO、Y2O3添加剂对原位反应制备ZTM/A12O3材料性能的影响

本文主要探讨了MgO、Y2 O3 添加剂对原位反应制备ZTM/Al2 O3 材料常温力学性能的影响。实验表明 :MgO可明显提高材料的烧结致密度 ;Al2 O3 的含量越高 ,MgO的添加越有利于材料常温抗弯强度的提高 ;MgO对材料韧性的贡献小于Y2 O3 ;Y2 O3 可明显改善材料的韧性 ,但对常温抗弯强度的提高作用不大 ;对烧结致密化的作用小于MgO。Y2 O3 改善材料韧性的原因是与ZrO2 形成固溶体。     

乙烯酮(双乙烯酮)下游产品废水的治理技术

乙烯酮(双乙烯酮)是十分重要的化工中间体,其下游产品较多。江苏某化工厂开发生产乙烯酮(双乙烯酮)下游产品三十多个,年生产规模三万多吨,是国内以乙烯酮(双乙烯酮)为中间体生产精细化学品的综合骨干企业。针对乙烯酮(双乙烯酮)下游产品废水特点,该厂结合企业实际,开展了产品优化,结构调整,清洁生产,资源循环利用,节水降耗等工作,从源头削减了污染物的生产。同时投资二千多万元新建预处理装置三套,6000m3/d废水生化处理装置一套,使全厂乙烯酮(双乙烯酮)下游产品的废水得到了有效的治理。     

几种乙炔加压设备性能的比较

阐述并比较了几种加压设备在乙炔加压清净过程中的性能和特点。     

三种煤样燃烧热的测定

本文通过三个厂家提供的三种煤样燃烧热的测定,由测定结果综合得出3号煤样燃烧最完全、燃烧热也最大,是三个煤样中最好的一种。     

Semi-empirical equation of state of metals. Equation of state of aluminum

A semi-empirical equation of state for metals is described. Its capabilities are demonstrated by the example of the equation of state for aluminum. New experimental data are presented on the location of the isentrope of aluminum for unloading from the state at p = 229.71 GPa on the shock adiabat to an aerogel (SiO₂) of density 0.08 g/cm³. __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 2, pp. 61–75, March–April, 2008.     

水泥水化热测定方法综述

水泥水化热是中、低热水泥和核电工程用水泥的一项关键的技术指标。全球范围内测定水泥水化热的方法有溶解法、直接法/半绝热法、等温传导量热法三种。本文总结了中、美、欧相关方法标准,对其测试原理、仪器设备、试验过程等方面进行了比对,并对其在领域的应用做了简单的概括。     

小议汽车涂装工艺设计对涂装成本的影响

论述了涂装工艺设计对涂装设备投资、涂装生产成本的影响。     

Calorimetric and Computational Study of Enthalpy of Formation of Diperoxide of Cyclohexanone

A thermochemical rather simple experimental technique is applied to determine the enthalpy of formation of Diperoxide of ciclohexanone. The study is complemented with suitable theoretical calculations at the semiempirical and ab initio levels. A particular satisfactory agreement between both ways is found for the ab initio calculation at the 6–311G basis This set level. Some possible extensions of the present procedure are pointed out.     

Measurement of the gradient of viscosity with composition of mixtures of non-ideal gases

A perturbation viscometer is a differential capillary viscometer that measures the logarithmic viscosity gradient of the viscosity-composition curve for gas mixtures. Measurements are made at different gas mixture compositions. Integration of the logarithmic viscosity gradients measured over the full composition range gives the mixture viscosity relative to the viscosity of one of the pure components of the gas mixture. This method is attractive because, for measurements of equal precision, integration of the gradients is potentially an order of magnitude more precise than measurement of the viscosities directly. It can also work at high and low temperatures and perhaps high pressures.The perturbation viscometer has been used to make measurements on ideal gas mixtures at ambient and elevated temperatures. The situation is more complicated when the gas mixtures are non-ideal. Extra effects due to density differences, molar volume change on mixing and differential thermal expansion may be measured in addition to the desired viscosity change producing systematic errors in the results. Thus, a more sophisticated apparatus is required. The standard perturbation viscometer has been modified to separate out the extra effects to permit measurement of the true change in viscosity. In addition, the theoretical operation of the modified apparatus has been revised to account for the design changes to permit calculation of the viscosity-composition profiles from the results.The apparatus has been tested using helium-HFC-125 mixtures and two new viscosity-composition profiles are presented for these mixtures at 23 and . Internal consistency tests have been used to confirm that the data produced are of high quality with an estimated uncertainty in the viscosity ratio data at of 0.9% and at of 1.5%.     

塔设备改造选型的分析

就当前扩产增容中塔设备设计和改造时板式塔和填料塔的选型问题加以分析。在评述目前国内常用的几种塔板和新型填料之后，着重介绍一种新型塔板（导向梯形浮阀塔板）和一种新型填料（波环填料——乾隆帕克）。     

Effect of degree of deacetylation of chitin on the properties of chitin crystallites

In the present article, chitin from crab shell was systematically deacetylated using a NaOH treatment with control of the reaction time. The degree of deacetylation, monitored using solid-state NMR, revealed that the reaction was pseudo-first order. Based on this, swollen and NaOH-saturated particles are proposed as the reaction system. The weight loss of the partially saponified and neutralized samples after HCl hydrolysis increased linearly with the degree of deacetylation. The crystallinity of the samples was found to increase after acid hydrolysis. According to conductimetric titration, the surface charge density of the crystallites, after acid hydrolysis, was found to increase with base treatment time. The effect of surface charge on the formation of a chiral nematic phase, due to the rodlike nature of the crystallites, was explored. These results show that because the contribution of charged particles to the ionic strength was significant the double layer compression was affected, especially since the surface charge density was close to the Manning limit. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:373–380, 1997