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恒定无碱铝硼硅酸盐玻璃中碱土金属氧化物的质量百分比不变,研究了SrO和CaO的相互替代对玻璃的热膨胀系数、应变点温度、玻璃转变温度、退火点温度、膨胀软化点温度等低温特征粘度参考点的影响。结果表明:玻璃的热膨胀系数随着n(SrO)/n(CaO)比值的增大而逐渐减小,低温特征粘度参考点在n(RO)/n(Al2O3)=0.96时达到极大值。 相似文献
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以红柱石和氧化铝为主要原料、聚苯乙烯粒子为造孔剂,通过烧结法制备莫来石泡沫陶瓷,借助XRD和SEM分析了烧成温度和骨料配比对获得莫来石相组成和结构的影响规律,并通过正交试验,探讨烧结温度、造孔剂加入量和骨料配比等工艺参数对制备莫来石泡沫陶瓷性能的影响.结果表明:造孔剂加入量对密度和强度的影响较大,烧结温度次之,骨料配比最小;最佳的因素水平为烧结温度1 450 ℃,EPS质量分数5%,骨料质量比m(红柱石)∶m(氧化铝)=80∶20,此时表观密度为0.52 g/cm3,抗折强度0.36 MPa. 相似文献
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选用两种不同纳米氧化铝粉体,采用直接掺杂法制备不同含量纳米氧化铝/聚酰亚胺复合薄膜.研究复合薄膜的导热系数与无机含量的关系,探讨纳米氧化铝粉体种类对复合薄膜导热性能的影响.结果表明:同一温度下,复合薄膜的导热系数随Al2O3含量的增加而增大;当纳米氧化铝含量小于15%(质量分数)时,选用亲水性纳米Al2O3粉体的复合薄膜导热性能比选用亲油性的复合薄膜的好;当纳米氧化铝的加入量为5%时,复合薄膜的强度和韧性均有明显增加;亲水性纳米氧化铝加入量为5%~10%时,复合薄膜的导热性能提高并能保持一定的力学性能. 相似文献
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以稀土氧化物Lu2O3作为单一添加剂,研究了稀土氧化物的添加量对氮化硅在相变过程密度、力学性能的影响规律.指出了氮化硅粉体的α→β相变率与稀土氧化物的添加量、粉体的热处理温度之间的关系.研究表明:加入Lu2O3添加剂后,β-Si3N4相的比率随着温度的升高呈明显上升趋势,当热处理温度达到1750℃时,β-Si3N4相的比率几乎接近或达到100%.随着Lu2O3含量的增加,在烧结过程中所形成的液相量随之增多,相对密度随之提高.随Lu2O3添加量的增加,试样的抗弯强度也增大,在10%时达到峰值,抗弯强度为1259.90MPa;氮化硅陶瓷的硬度随Lu2O3添加量的变化规律与抗弯强度的变化规律相似.Lu2O3含量在10%时,试样的断裂韧性值达到最大,为6.277MPa·m1/2. 相似文献
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新一代高超声速飞行器热端部件服役温度不断提高,对表面防护涂层的相稳定性和抗烧蚀性能提出了更高的要求。本工作针对传统过渡金属氧化物ZrO2、HfO2涂层开展高熵化设计,采用高温固相反应结合超音速大气等离子喷涂制备(Hf0.125Zr0.125Sm0.25Er0.25Y0.25)O2-δ(M1R3O)、(Hf0.2Zr0.2Sm0.2Er0.2Y0.2)O2-δ(M2R3O)、(Hf0.25Zr0.25-Sm0.167Er0.167Y0.167)O2-δ(M3R3O)三种高熵氧化物涂层,探究稀土组元含量对高熵氧化物涂层的相结构演变规律、相稳定性以及抗烧蚀性能... 相似文献
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掺杂Y_2O_3,Sm_2O_3对氧化铝瓷介电性能的影响 总被引:1,自引:0,他引:1
研究了Y2O3、Sm2O3对氧化铝瓷烧结性能、介电性能和显微组织的影响。研究结果表明,Y2O3、Sm2O3在氧化铝瓷的烧结过程中可以显著降低氧化铝瓷的烧成温度,抑制晶粒生长,使晶粒尺寸变小,提高了陶瓷的致密性,降低了试样的结构损耗。掺稀土氧化物的氧化铝瓷在1600℃保温2h烧结后,相对密度达98.8%以上,介质损耗达到4.2×10-3。 相似文献
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刚玉莫来石复相陶瓷力学性能的影响因素分析 总被引:2,自引:0,他引:2
本文采用正交设计方法研究了硅微粉、氧化铝微粉及烧结温度对刚玉莫来石复相陶瓷常温强度和高温强度的影响机制.结果表明:氧化铝微粉对高温强度的影响较大,硅微粉次之,烧结温度最小.适当降低氧化铝微粉的含量,并提高硅微粉的含量和烧结温度,可以提高复相陶瓷的高温强度.通过调节硅微粉、氧化铝微粉及烧结温度可控制刚玉莫来石复相陶瓷的显微结构,改善刚玉莫来石复相陶瓷的高温强度. 相似文献
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潜油电泵在出砂油井中运行时,常常因磨损严重造成离心泵损坏,致使离心泵的工作寿命较短。通过对出砂油井中电泵机组的解剖分析,认为砂粒对离心泵的磨损是造成机组破坏的主要原因。文中描述和分析了磨损对潜油电泵机组的破坏特征,并根据油井的先期防砂和出砂情况,对潜油电泵的防砂技术进行初步研究。 相似文献
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Suzan S. Ibrahim Ali Q. Selim Ayman A. Hagrass 《Particulate Science and Technology》2013,31(6):590-595
A representative white sand sample was investigated for glass industry. Complete characterization of the sample was conducted. Chemical analysis of the sample showed that iron and alumina oxides reached 0.046% and 0.044%, respectively. Dry sieving was carried out to reject +0.6 mm and ?0.10 mm fractions from the sample. The classified ?0.6 + 0.1 mm product was directed to attrition scrubbing. The effect of pulp density, attrition impeller speed, attrition time and mode were studied. The attrition sand product was further subjected to gravity separation using “Wilfley” shaking table. Different working conditions of table separation i.e., sand feeding rate, stroke length, deck inclination, and dressing water flow rate were optimized. Results showed that the classified ?0.6 + 0.106 mm sand product contained 0.039% Fe2O3 and 0.041% Al2O3 matched the specifications for the fourth-quality sand for sheet and plate glass industry. However, iron and alumina oxides contents were further decreased to 0.025% and 0.0164% after the attrition process. The attrition product accepted as second quality for flint containers and table ware applications. The final sand product after shaking table contained 0.0180% Fe2O3 and 0.090% Al2O3, was applicable for the first quality for optical applications. 相似文献
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Removal of As(III) in a column reactor packed with iron-coated sand and manganese-coated sand 总被引:1,自引:0,他引:1
The applicability of manganese-coated sand (MCS) and iron-coated sand (ICS) for the treatment of As(III) via oxidation and adsorption processes was investigated. Scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to observe the surface properties of the coated layer. In the batch adsorption, the adsorption rate of As(V) onto ICS was greater than that of As(III), and ICS showed a greater adsorption capacity for the removal of As(V) than As(III). From a bench-scale column test, a column reactor packed with both MCS and ICS was found to be the best system for the treatment of As(III) due to the promising oxidation efficiency of As(III) to As(V) by MCS and adsorption of As(V) by both MCS and ICS. From these bench-scale results, the treatment of synthetic wastewater contaminated with As(III) was investigated using a pilot-scale filtration system packed with equal amounts (each 21.5 kg) of MCS at the bottom and ICS on the top. The height and diameter of the column were 200 and 15 cm, respectively. As(III) solution was introduced into the bottom of the filtration system, at a speed of 5 × 10−3 cm s−1, over 148 days. The breakthrough of total arsenic in the mid-sampling (end of the MCS bed) and final-sampling (end of the ICS bed) positions began after 18 and 44 days, respectively, and showed complete breakthrough after 148 days. Although the breakthrough of total arsenic in the mid-sampling position began after 18 days, the concentration of As(III) in the effluent was below 50 μg L−1 for up to 61 days. This result indicates that MCS has sufficient oxidizing capacity for As(III), and 1 kg of MCS can oxidize 93 mg of As(III) for up to 61 days. When the complete breakthrough of total arsenic occurred, the total arsenic removed by 1 kg of MCS was 79.0 mg, suggesting MCS acts as an adsorbent for As(V), as well as an oxidant for As(III). From this work, a filtration system consisting of both MCS and ICS can potentially be used a new treatment system to simultaneously treat As(III) and As(V). 相似文献
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目的 针对复杂薄壁铸件高性能制造难题,本研究提出多材料砂型增材制造一体化共面铺砂工艺,实现多材料砂型的整体成形。方法 基于多材料砂型增材制造振动铺砂装置,通过优化固化剂含量、铺砂器开口宽度和振动频率,实现两种型砂材料的定量落砂。通过显微镜扫描表征和图像处理,系统地研究了在不同铺砂速度下的铺砂质量和型砂层厚变化规律。结果 在一定范围内,固化剂含量的增大会减小落砂流量,铺砂器开口宽度与振动频率的增加均提高落砂流量,当硅砂固化剂含量为2.3wt.‰、铬铁矿砂固化剂含量为2wt.‰、铺砂器开口宽度为2 mm、振动频率为500 Hz时,两种型砂落砂流量相等;在此基础上,铺砂速度提高会增加模糊长度,降低铺砂界面连接处和铺砂末端粗糙度。当铺砂速度为53.92 mm/s时,实现0.6 mm层厚的多材料稳定持续铺砂,界面连接效果好、铺砂精度高。结论 本研究突破多材料砂型增材制造一体化共面铺砂工艺,实现多材料砂型多区域定量均匀铺砂。 相似文献
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介绍用电熔镁砂制作4.5t真空感应炉坩埚,重点介绍使用电熔镁砂的粒度配比及相应的烘炉、洗炉工艺,实践证明,不仅可以大幅度降低成本,而且炉龄稳定,容易清除粘附在坩埚壁上的渣子。 相似文献
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测试了高炉重矿渣和重矿渣砂的组成、结构和性能,对比研究了重矿渣砂和天然河砂对水泥砂浆工作性能和力学性能的影响,从界面结构和孔结构角度分析了重矿渣砂提高水泥砂浆力学性能的作用机理。结果表明:重矿渣砂主要是由许多表面粗糙的颗粒和一些重矿渣微粉所组成,其粗糙的表面改善了骨料颗粒与基体之间的界面结构;重矿渣砂中重矿渣微粉降低了骨料的空隙率,改善了新拌砂浆的粘聚性和流动性,提高了硬化砂浆的致密性。利用重矿渣砂替代天然河砂可以配制出力学性能更好的砂浆,但会降低砂浆的工作性能。 相似文献
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Studies of sand particle characteristics (shape, voids content, filler particle size distribution) and rheology of concrete (slump-flow, yield stress and plastic viscosity) show that the 0.125/2 mm particle shape and ≤0.125 mm filler properties are the most important factors for concrete workability when the sand grading 0/8 mm is kept constant. By normalizing the maximum variation of rheology (slump-flow value in mm) obtained in mixes where different size fractions are exchanged, the fraction ≤ 0.125 mm was found to have around 6–8 times larger effect on rheology per unit volume % exchanged, compared to the coarser sand fractions: ≤0.125 mm = 35.2 mm/%; 0.125/2 mm = 4.9 mm/%; 2/5 mm = 6.0 mm/% and 5/8 mm = 3.8 mm/%. 相似文献