烧成制度对铝质高强瓷显微组织结构的影响

本文利用X-ray衍射与SEM等分析测试手段,探讨了烧成制度对微观结构与相组成的影响,从而为获得高性能的瓷坯探索出合理的烧成工艺制度,并提出了必要的依据。     

高铬刚玉涂料及防粘砂机理研究

试验了醇基高铬刚玉粉涂料并在铸钢生产中应用,采用电子探针分析了高温钢液作用过的涂层断面结构,探讨了其防粘砂机理。结果表明,这种涂料有较好的防粘砂效果;发现了钢液表面的FeO和砂型中的水玻璃向涂层中渗透,涂层中耐火骨料颗粒表面熔融,烧结成彼此相连的大块状,骨料间隙填充硅酸铝、铁、钠玻璃相,形成一定厚度的致密隔离层,有效地防止了钢液的渗透。     

刚玉·红宝石·蓝宝石的再认识

为了使广大消费者能更好地认识、了解彩色宝石中最珍贵的红宝石和享有“帝王石”之称的蓝宝石 ,对红宝石、蓝宝石 (刚玉 )矿的矿床地质、资源分布及开采利用历史作了简明的回顾和阐述。针对近几年来国际珠宝市场中红宝石、蓝宝石又重新成为主要畅销产品的趋势 ,介绍了泰国有关珠宝机构提出的红宝石分级体系 ,国际有色宝石协会将粉红色、浅红色宝石级刚玉归入红宝石中的规定 ,国际市场上有关红宝石、蓝宝石的供求动向以及在具有永久纪念意义的红宝石、蓝宝石的收藏情况等方面的资讯。     

锆刚玉加入对刚玉-尖晶石浇注料性能的影响

在刚玉-尖晶石浇注料的配比组成中分别加入ZrO2质量分数为28.46%和38.47%的两种电熔锆刚玉颗粒,研究了电熔锆刚玉颗粒的粒度(5～3、3～1和1～0.5 mm)、加入量(质量分数分别为3%、5%和8%)对刚玉-尖晶石浇注料的加热永久线变化率、烧后常温抗折强度、高温抗折强度及热震后弹性模量的影响,并观察了试样的显微结构。结果表明:1)试样的加热永久线变化率随锆刚玉粒度的增大而增大,随锆刚玉加入量的增多而增大,引入锆刚玉Z40的试样的加热永久线变化率基本上比引入锆刚玉Z25的大;2)烧后试样的常温抗折强度、高温抗折强度和弹性模量均以空白试样的为最大,均随锆刚玉粒度的减小而增大,随锆刚玉加入量的增多而减小;3)在刚玉尖晶石浇注料中适当加入锆刚玉而产生微裂纹,尽管降低了材料的强度和弹性模量,但对提高抗热震性有一定的积极作用。     

Phase evolution and lightweight application of dolomite@Al2O3 spherical particle with core–shell structure

Dolomite@Al₂O₃ spherical particles with core–shell structure were fabricated by using the dolomite powders as the core and wrapping corundum powders on their surface. The phase evolution and microstructure of the dolomite@Al₂O₃ spherical particles with different firing temperatures were studied. As the spherical particles fired at different temperatures, the dolomite in the spherical core decomposed into MgO and CaO. Due to the Kirkendall effect, MgO and CaO diffused into the shell of the spherical particle and left Kirkendall holes in the core. The holes produced by the Kirkendall effect and the decomposition of dolomite act together to form a hollow structure in the center. And during the diffusion process, MgO and CaO reacted with corundum to generate spinel and calcium hexaaluminate. A small amount of spinel and calcium hexaaluminate can form a ternary compound Ca₂Mg₂Al₂₈O₄₆. Moreover, simulation software Factsage and Abaqus were used separately to help prove the phase evolution and the introduction of spherical particles to the properties of refractories. To test the lightweight effect of dolomite@Al₂O₃ spherical particles on refractories, it was introduced into spinel–corundum refractories as medium particles in different content and fired at different temperatures. The results show that after firing at 1650°C for 3 h with introducing 30% dolomite@Al₂O₃ spherical particles, the samples can reach a high compressive strength (128 MPa), high refractoriness under load (1683°C), and low thermal conductivity (1.79 W (m K)⁻¹).     

炉缸复合棕刚玉砖蚀损机理的探讨

采用实验模拟和现场取样的方法研究了有害元素对复合棕刚玉砖的蚀损机理,研究表明:复合棕刚玉砖具有较好的抵御渣、铁和Pb、Zn侵蚀渗透的能力,而对碱金属K、Na的抗渗透能力较差,炉缸复合棕刚玉砖蚀损是有害元素共同作用的结果,侵入砖体的顺序依次是K、Na、Zn、Pb.     

The influence of mechanochemical treatment of sintered submicrocrystalline corundum substrates on the structure of bioglass composites

The influence of mechanochemical treatment of submicrocrystalline sintered corundum on the structure of bioglass composites containing α-Al₂O₃ and CaO-SiO₂-P₂O₅ glasses was examined in the context of the possibility to form hydroxyapatite after being immersed in the simulated body fluid solution. Measurements of specific surface area and size and X-ray analysis of submicrocrystalline sintered corundum were conducted. Bioglass composites were obtained by placing submicrocrystalline sintered corundum grains in the CaO-SiO₂-P₂O₅ sol system, gelling and sintering at 800°C. The specimens were examined under a scanning electron microscope before and after immersion in the simulated body fluid solution for 24 and 120 h. Using the VCS algorithm, calculations of thermodynamic stability of compounds occurring in these bioglass composites were carried out, verifying the X-ray analysis. Original Russian Text ? B. Staniewicz-Brudnik, S. Szarska, K. Gamrat, 2008, published in Sverkhtverdye Materialy, 2008, Vol. 30, No. 6, pp. 40–48.     

熔融制样-X射线荧光光谱法测定黑刚玉中6种组分

黑刚玉是一种以Al₂O₃、SiO₂和TiO₂为主要成分的新型环保材料,其化学成分的分析一般采用滴定法、分光光度法或原子吸收光谱法等,这些方法操作相对繁琐、流程长。实验采用H₃BO₃-Li₂CO₃ 混合熔剂(m∶m＝7∶3)按质量比为1∶10的稀释比进行熔融制样,加入0.15 g NH₄I脱模剂,有效地消除了矿物效应、粒度效应。实验选择矾土、黏土、焦宝石等与黑刚玉组分相似的标准物质和人工合成校准样品建立校准曲线,各组分校准曲线的相关系数均大于0.998,实现了熔融制样-X射线荧光光谱法对黑刚玉中Al₂O₃、SiO₂、Fe₂O₃、TiO₂、CaO和MgO含量的同时测定。对黑刚玉样品进行准确度考察,实验方法的测定值与其他方法的测定值吻合较好,各组分测定结果的相对标准偏差(RSD)均小于2.0%。     

不锈钢金相试样上类夹渣缺陷形成原因分析

对经过磨平、粗磨、细磨和精抛环节后多种牌号不锈钢中非金属夹杂物评级时,发现检验面存在许多形状不规则的类夹渣冶金缺陷。用光学显微镜、扫描电镜对该缺陷形貌进行观察,并采用能谱仪对缺陷化学成分进行定性定量分析,同时采用现场质量管理中的人、机、料、环、法、测六要素从炼钢到制备样品整个环节逐一对比排查,并进行不同材质的砂纸对比试验。结果表明,不锈钢金相试样的类夹渣缺陷主要含有O、Al、Zr元素,是在磨平阶段使用锆刚玉砂纸造成的。     

刚玉–莫来石–镁铝尖晶石复合陶瓷的原位合成及热震行为

以α-Al2O3、苏州土、滑石和石英为主要原料,采用无压烧结制备了刚玉–莫来石–镁铝尖晶石多相复合陶瓷,研究了烧结温度对样品的体积密度、线性收缩率和吸水率等烧结性能以及机械性能的影响。通过X射线衍射和扫描电子显微镜分析了复相陶瓷热震前后的物相组成和显微结构。结果发现：经1480℃烧结的样品吸水率为0.19%,体积密度为3.06g/cm3,抗折强度达99.59MPa,复合材料有较好的热震性能,1100℃空冷热震损失率仅6.9%,可耐受17次热冲击。该复相陶瓷可作为潜在的太阳能热发电材料。