微晶玻璃低温脆塑转变机理的研究

微晶玻璃是一种新型的硬盘基板材料,目前大多采用超精密研磨和抛光进行加工.本文针对微晶玻璃低温抛光加工过程,研究了低温条件下微晶玻璃的脆塑转变机理,采用维氏硬度计研究了微晶玻璃在不同温度下的硬度以及裂纹的产生、扩展及特征,分析了温度对微晶玻璃脆塑转变的影响.结果表明:不同温度下,随着载荷的增加,微晶玻璃都经历了从塑性变形到脆性断裂的转变过程;随着温度的降低,微晶玻璃的显微硬度逐渐增加而裂纹长度减小.     

生物微晶玻璃的最新进展

生物微晶玻璃是很有前途的一类生物材料,各国对其研究非常活跃.目前,生物材料正向分子水平设计的方向发展,本文试图对最近几年的国内外生物微晶玻璃的研究状况和今后发展趋势予以介绍.     

微晶玻璃新材料

本文简介了几种近年来新开发的微晶玻璃新材料,如高强度、高韧性微晶玻璃,表面高压缩增强微晶玻璃,纤维增强微晶玻璃复合材料,氟云母微晶玻璃柔性无机膜,发光透明微晶玻璃,核废料固化用微晶玻璃,生体修补用微晶玻璃及微晶玻璃建筑材料等.     

光敏微晶玻璃新材料

本文介绍光微晶玻璃新材料制备方法、产品性能、用途及应用意义。     

仿软玉的微晶玻璃

阐述了软玉特征与仿软玉的要求,介绍了仿软玉微晶玻璃成分与工艺,最后提出了仿软玉微晶玻璃研究方向。     

尾矿制备微晶玻璃的研究进展

尾矿制备微晶玻璃是尾矿的综合利用的一种新的途径.本文综述了微晶玻璃的特性及制备工艺,介绍了尾矿作为原料在微晶玻璃生产中的应用.分别讨论了不同尾矿制备微晶玻璃的工艺及其对微晶玻璃微观结构与物化性能的影响.从尾矿综合利用的角度,分类论述了金属尾矿及非金属尾矿制备微晶玻璃的最新研究进展,展望了尾矿微晶玻璃的发展方向及应用前景.     

Characterization of High-Fracture Toughness K-Fluorrichterite-Fluorapatite Glass Ceramics

Stoichiometric K-fluorrichterite (Glass A) and the same composition with 2 mol% P₂O₅ added (Glass B) were prepared and then heat-treated isothermally from 550°–1000°C with 50°C intervals. Samples were characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The biaxial flexural strength and indentation fracture toughness of heat-treated glass specimens were also determined for both materials. XRD traces and TEM images showed similar phase evolution and fine microstructures for both systems at ≤950°C, with mica and diopside reacting with residual glass to form K-fluorrichterite as the temperature was increased from 650°C. However, in Glass B, fluorapatite was also present at >800°C. In contrast, coarser microstructures were observed at 1000°C, with larger K-fluorrichterite (20 μm) and enstatite (10 μm) crystals in Glasses A and B, respectively. The highest fracture toughness (2.69 ± 0.01 MPa·m^1/2) and biaxial strength (242.6 ± 3.6 MPa) were recorded for Glass B heat-treated at 1000°C. This was attributed to the presence of enstatite coupled with an interlocked lath-like crystalline microstructure.     

油井土、废玻璃基多孔陶瓷的制备及结构表征

利用油井土、废玻璃作为主要原料,同时以碳酸钙作为造孔剂,通过控制烧结过程,最终制备多孔陶瓷材料,并利用XRD、SEM等对样品进行结构表征。本研究的目的是为了研究油井土、废玻璃、碳酸钙的比例以及烧结温度对孔隙率、机械强度、体积密度、吸水率、微观结构和结晶程度的影响。结果表明样品A3呈现大孔均匀的微观结构,是通过添加35wt％油井土、40wt％废玻璃、20wt％碳酸钙、5wt％硅酸钠在较低的烧结温度下来获得,其孔隙率、抗压强度、抗弯强度、体积密度和吸水率的值分别为52．38％、4．43 MPa、12．59 MPa、1．07 g／cm3和29．56％。并观察到其机械强度、吸水率和微观结构（孔径及孔径分布）有良好的相关性。     

Processing of Cellular Glass Ceramics

Commercial polyurethane foams with a monomodal pore size distribution were chosen to produce LZSA (Li₂O–ZrO₂–SiO₂–Al₂O₃ system) glass–ceramic foams by the polymeric sponge method. A suspension containing LZSA glass–ceramic, bentonite, and sodium silicate was prepared in water and isopropanol to impregnate the polymeric foams by dip coating. The suspension was characterized by rheological measurements. The effect of the solvent on the microstructure and physical properties on the LZSA foams was evaluated. The cellular microstructure of the glass–ceramic foams was characterized by scanning electron microscopy (SEM) and micro-computer X-ray tomography (μ-CT). LZSA foams prepared with isopropanol suspension exhibited higher mechanical strength under compression than those prepared with water.     

Brittle Failure Prediction of Ceramics Using a Multiscale Approach

Brittle failure is classically modeled by the Weibull distribution, based on a phenomenological approach. The procedure fails if the distribution of the failure-initiating defects varies within material batches and may lead to a wrong conclusion about the predictive power of the model. The purpose of this paper is to highlight this problem, which can occur with brittle materials such as ceramics. This study, based on the results of tensile and bending tests made on silicon nitride specimens, consists of three steps: (i) micrographic and fractographic studies are performed to determine the defect-size density in each type of specimen and the mechanical behavior of the defects, (ii) the classical modeling with a Weibull distribution is shown to fail to predict the results, and (iii) a new approach for the identification of a fracture model is developed, based on step (i). The fracture prediction is computed from the actual defectsize distribution in each material batch, so that the procedure can be adapted to changes in the defect-size distribution caused by the manufacturing process.     

玻璃陶瓷材料发展的回顾与展望

本文回顾了玻璃陶瓷材料的发展过程,特别对近几年来玻璃陶瓷材料的研究进展进行了概述和分析,在此基础上,对玻璃陶瓷的发展趋势进行了探讨。     

激光玻璃陶瓷的研究进展

简述了激光玻璃陶瓷的主要类别,介绍了其在通讯信息、工业生产、生化医疗、军事等领域的应用,并提出其将来可能成为玻璃或单晶的替代材料。