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实验以SiO2-B2O3-Al2O3-R2O体系作为基础结合剂,选择ZrO2作为添加剂,通过差示扫描量热分析仪、X射线衍射仪、扫描电镜等检测手段,研究其含量对陶瓷结合剂及CBN磨具性能的影响.结果表明,随ZrO2含量的增加,陶瓷结合剂耐火度升高,流动性变差;当ZrO2含量为1%时,陶瓷结合剂抗折强度达到75 MPa,显微硬度838 MPa,这得益于结合剂中ZrSiO4细晶的析出;此时CBN磨具有最大抗折强度45 MPa和最大体积密度2.32 g·cm-3,且结合剂与磨粒润湿性好,磨具组织致密,气孔分布均匀,微观结构良好. 相似文献
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采用溶胶凝胶法制备了SiO2-Al2 O3-Na2 O基玻璃涂层CBN磨料,通过扫描电子显微镜(SEM)、X射线能谱仪(EDS)、热膨胀仪及力学性能测试仪表征了玻璃涂层CBN磨料的性能,并将玻璃涂层CBN磨料应用于陶瓷结合剂磨具.实验结果表明:SiO2-Al2 O3-Na2 O基涂层玻璃的热膨胀系数与CBN磨料相匹配,对CBN颗粒形成良好的包裹润湿.玻璃涂层的CBN磨料单颗粒抗压强度和冲击韧性均比未涂层的磨料有所提高.在陶瓷结合剂CBN磨具中玻璃改性增强了CBN磨料与结合剂的界面区结合,提高了磨料与陶瓷结合剂之间的粘结力. 相似文献
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为了改善多孔氧化铝陶瓷的性能,考察了陶瓷悬浮液的固含量、造孔剂和其他添加剂种类对生坯体和烧结体机械强度的影响。发现固含量由53%减少至45%和40%时,机械强度大大降低。当向料浆中添加7%三种不同类型的淀粉时,气孔率没有明显提高;当用Al(OH)3替代30%的Al2O3时性能也没有改善。但采用直接发泡法制备多孔隔热陶瓷(Al2O3固含量53%,无添加剂),热导率与其他三种商用隔热陶瓷砖相比有优势,气孔率达到81%,机械强度达到15MPa。 相似文献
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文章根据制造陶瓷结合剂cBN磨具的特殊要求,对磨具用低温高强度陶瓷结合剂及其性能进行了深入研究。通过调整陶瓷结合剂中各氧化物成分含量,使用SKZ-500型数显抗折试验机、X光衍射(XRD)、电子扫描电镜(SEM)等测试分析仪器,对陶瓷结合剂的性能进行了测试。最后确定了低温高强度陶瓷结合剂的化学成分配比范围:w(Si02)为40%~60%,w(Al2O3)为5%~15%,w(B2O3)为10%~25%,w(R2O)为2%~12%,w(R0)为5%~20%。 相似文献
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调节结合剂配方,改善结合剂性能是提高CBN磨具使用性能的一个重要途径.本文研究了Na2O-Li2O、Na2O-K2O、Na2O-Li2O-K2O不同混合碱对CBN磨具用硼铝硅酸盐玻璃结合剂熔融温度、抗折强度、矿物组成、热膨胀系数及热膨胀软化温度的影响.结果表明,在R2O总量为20%不变的情况下, 调节碱金属氧化物的组成及比例可使玻璃结合剂的某些性能出现明显的"混合碱效应":抗折强度从40.37 MPa增至51.89 MPa,热膨胀系数从10.32×10-6/℃降至 8.40×10-6/℃, 添加三元混合碱系列的玻璃结合剂性能比添加二元混合碱系列的性能更好. 相似文献
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将金属铝粉、纳米Al2O3粉引入基础陶瓷结合剂,通过红外光谱分析陶瓷结合剂玻璃结构,X射线衍射表征其物相变化,并测试其耐火度,利用扫描电镜分析陶瓷结合剂立方氮化硼(CBN)复合材料的微观结构,并测试抗折强度,系统分析了金属铝粉、纳米Al2O3粉的单掺及复掺对陶瓷结合剂性能的影响。结果表明,金属铝粉使陶瓷结合剂耐火度升高,玻璃结构没有明显改变,部分铝粉转变为Al2O3,添加金属铝粉的陶瓷结合剂CBN复合材料抗折强度随烧结温度升高而提高。纳米Al2O3粉使陶瓷结合剂耐火度降低,呈玻璃相,但有少量Al2SiO5晶体和LixAlxSi3-xO6晶体析出,添加纳米Al2O3粉的陶瓷结合剂CBN复合材料烧结温度720 ℃时出现较高抗折强度,达93.7 MPa。金属铝粉和纳米Al2O3粉的复掺有利于玻璃网络结构的键合,陶瓷结合剂以玻璃相为主,也有少量晶体析出,二者复掺对提高陶瓷结合剂CBN复合材料抗折强度更有优势,但烧结温度也相应升高,烧结温度740 ℃时抗折强度达最高值,为97.4 MPa。 相似文献
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采用传统电子陶瓷制备工艺制备了(1-x)BaTiO3-xBi0.5Na0.5TiO3(x=O.2~0.6)陶瓷,研究了不同Bi0.5Na0.5TiO3(BNT)含量下陶瓷的微结构特征和介电性能。结果表明:在BNT为0.2~0.6mol时,陶瓷样品均具有单一的钙钛矿结构,陶瓷的晶粒形状和大小随BNT含量的增加发生变化,BNT含量增加时样品的晶粒趋于减小,样品结构更为致密。陶瓷样品都具有稳定的介电性能,较高的介电常数,较低的介电损耗、BT-BNT40的介电稳定性最好。居里温度随BNT含量的增加而升高、当BNT含量为0.6mol时,T=210℃。 相似文献
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粉煤灰提取Al2O3及其改性聚丙烯的研究 总被引:1,自引:0,他引:1
采用碱焙烧法从粉煤灰中提取Al2O3,将提取的Al2O3用于聚丙烯(PP)改性研究,并以市售Al2O3改性的PP为参考,考察了Al2O3对PP力学性能、微观形态的影响。结果表明,提取的Al2O3改性PP的拉伸性能和冲击性能与市售Al2O3相当;当Al2O3含量增加到2 %时,PP的拉伸断面均由平整结构变为轻微的层状结构,此时拉伸和冲击性能达到最佳,拉伸强度提高约6 %、伸长率提高约23 %、冲击强度提高约14 %;当Al2O3含量继续增加到5 %时,层状结构更为明显,改性PP的冲击强度急剧下降。 相似文献
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ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l/3为氧气,2/3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中:A一混… 相似文献
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P. P. Budnikoff 《Journal of the American Ceramic Society》1924,7(11):817-820
The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO3 and determination of CaO by KMnO4 titration, the SO3 by Andrews method of titration of BaCrO4 has been found to give very reliable results with the least consumption of time. 相似文献
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A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases. 相似文献
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A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.
Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology. 相似文献
Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology. 相似文献
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ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES 总被引:5,自引:0,他引:5
Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log10 viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log10 viscosity as a function of soda content are smooth up to 50% Na2O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO2, 2Na2O) due to Molecular Substitution of CaO, MgO and Al2O3 for Na2O The effect is clearly brought out by plotting (from the results of English) the change of log10η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature Ta. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log10η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A12O3) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al2O3) per 100°. At the aggregation temperature the change of log10η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al2O3. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log10η due to substitution of an oxide for Na2O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na2O-CaO-SiO2. Change of Viscosity of Glass (4SiO2, 2Na2O) due to of Substitution of B2O3 for SiO2 The change of log10η (from the results of English) is plotted as a function of temperature, and also the change of log10η per per cent B2O3. The curves are more complex than for the substitution for Na2O. 相似文献
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面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。 相似文献
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用两个形状指数表征粉煤灰颗粒形貌的研究 总被引:5,自引:0,他引:5
引用两个形状指数表征颗粒形状的概念,即先将颗粒形状近似为椭圆,再将椭圆图像分离:以圆为基准的颗粒宏观形状指数δ;以光滑椭圆为基准的颗粒轮廓凹凸度,即微观形状指数ζ。分析和发展了近似椭圆模型。并运用图像分析仪对粉煤灰、水泥样品进行实验。结果表明,粉煤灰颗粒的两个形状指数δ和ζ都大于水泥颗粒。证明粉煤灰颗粒的球形度、表面光滑度优于水泥,而且,随着粒径增大,δ和ζ呈下降趋势,表明磨制颗粒越粗。(?)粒形状越不规则。文中还运用近似椭圆模型再现了颗粒的模拟图像。 相似文献