FeO-Fe2O3-CaO-SiO2体系铁磁微晶玻璃的磁性及生物活性

具有生物活性和磁性的微晶玻璃材料被认为是温热疗法治疗癌症的有效热种子材料.本文制备了添加少量B2O3和P2O5后的FeO-Fe2O3-CaO-SiO2体系铁磁微晶玻璃,并进行了微观结构分析、XRD分析、磁性检测以及生理模拟液的浸泡实验.实验结果表明,制备的微晶玻璃材料同时具备磁性和生物活性这两种重要性能.不经过核化处理在1000℃晶化2h能够获得较理想的磁铁矿主晶相和硅灰石次晶相均匀致密分布的微观组织,所得微晶玻璃具有最佳的磁性能.铁含量提高能够增加微晶玻璃的磁性,然而会抑制微晶玻璃表面羟基磷灰石的形成,从而降低其生物活性.     

CeO2掺杂对二氧化锡电极力学性能的影响

以氧化铈作掺杂添加剂,通过对玻璃熔窑用二氧化锡电极掺杂一定量的氧化铈,分析电极的力学性能和微观结构,结果表明,氧化铈对二氧化锡电极的抗折和增韧效果显著,一定程度上能促进SnO2晶相的形成和生长,使氧化锡晶体成三维生长,大大提高了电极的力学性能,同时对电极的导电性也有明显的效果.     

Al2O3基复合材料中纳米SiC对微观结构的影响

本文从烧结温度、基体晶粒大小、断裂方式、SiC在基体中的分布等几个方面研究了纳米SiC颗粒的加入对Al2O3微观结构的影响．用非均相沉淀工艺制备的纳米SiC-Al2O3复合粉体，具有Al2O3颗粒包裹纳米SiC的特点，提高了烧结温度，明显使Al2O3晶粒变小，并且抑制晶粒异常长大，试样的断裂方式从以沿晶断裂为主转变到以穿晶断裂为主．SiC在Al2O3中分布均匀，大部分位于晶粒内，少部分位于晶界上．这种微观结构有利于力学性能的提高．     

49MnVS3非调质易切削钢汽车曲轴的失效分析

49MnVS3非调质易切削钢汽车曲轴在进行发动机例行工况试验时发生断裂。对失效曲轴进行了化学成分、金相组织、力学性能和断口分析。发现该曲轴材料晶粒粗大，铁素体大都呈网状沿晶分布；材料的韧性差；宏观下，裂纹源区萌生于断口边缘部位，该处未发现刀痕及外伤；断口微观形貌为沿晶断裂和穿晶断裂，有较明显的脆性特征。结论：曲轴断裂是始、终锻温度偏高所致。     

物理金相三级人员试题参考答案

二　问答题2 6.当疲劳裂纹扩展速率很低时 ,即ｄａｄＮ小于每周 10 - 5～ 10 - 4ｍｍ时 ,断口微观上常呈无特征的光面 ,或近似于静力断裂的特征。2 7.在蠕变过程中沿晶开裂有楔型 (Ｗ )和椭圆型 (Ｏ)断裂。通常 ,较低的试验温度和较高的应力以及较高的蠕变速率有利于楔型裂纹的形成 ;但当较高的温度和较低应力及应变时 ,晶界空穴将占优势 ,这时就形成椭圆形裂纹。2 8.这两种断裂都是由于环境介质侵蚀而引起的沿晶断裂。应力腐蚀的断口可呈脆性断口也可呈塑性断口。断裂方式有沿晶断裂和穿晶断裂两种 ,碳钢及低合金钢多半是沿晶断裂 ,而奥氏…     

纳米Al2O3对纳米4YSZ复相陶瓷结构和性能的影响

以纳米4YSZ和纳米Al2O3粉末为原料,对掺少量Al2O3的4YSZ无压烧结体的烧结特性、结构和性能进行了研究.掺适量的Al2O3可降低烧结温度,减缓4YSZ晶粒的长大.少量的交接渗透强化了晶界,烧结体断裂倾向于穿晶断裂,提高了烧结体硬度.     

SnO2添加剂对AgCuOIn2O3复合材料电接触性能的影响

采用反应合成法结合塑性变形工艺制备了不同SnO2含量的AgCuOIn2O3SnO2电触头材料,在JF04C触点材料测试机上对不同SnO2含量的电触头材料进行电接触实验,研究了该材料的接触电阻、抗熔焊性和材料转移特性,并通过扫描电镜对试样阴/阳表面电侵蚀下的微观形貌进行了分析.结果表明AgCuOIn2O3SnO2触头材料...     

纳米ZrO2与微米Al2O3复合陶瓷的断裂模式

研究了两种微米Al2O3与纳米ZrO2复合陶瓷的裂纹扩展过程与显微结构的关系.结果表明,Al2O3晶粒内部形成纳米级或亚微米级ZrO2颗粒,是复合陶瓷的断裂模式从沿晶断裂向穿晶断裂转化的主因.ZrO2含量较低有利于Al2O3晶界迁移包裹纳米ZrO2形成内晶结构;而ZrO2含量较高使主晶相长大受到抑止,不利于形成内晶结构,趋向于沿晶断裂.裂纹穿晶扩展需要的驱动力比沿晶断裂大,故裂纹扩展阻力曲线的上升趋势更加显著.裂纹穿晶扩展路径主要取决于内晶颗粒产生的弹性应力场的性质.     

无压烧结制备氧氮化硅陶瓷

以β－Si3N4和ＳiO2粉末为原料,以ＭgAl2O4为烧结添加剂,通过无压烧结制备出致密的Ｓi2N2O陶瓷材料,所得材料由柱状Ｓi2N2O颗粒和少量β－Si3N4颗粒复合组成,研究了烧结温度对材料显微结构的影响,发现材料的断裂大部分是穿晶断裂。     

透明BaO·B_2O_3玻璃陶瓷的表面形貌、结构特征及光学性能

以BaCO3、H3BO3为原料，经高温熔触及控制热处理，获得了BaO·B2O3透明玻璃陶瓷.利用XRD、SEM等手段研究了该材料的结构特征及表面形貌．结果表明，在玻璃表面得到了含有单一β-BaB2O4（BBO）晶相结构的析晶薄膜层，薄膜表面均匀，单股厚度约2μm，晶粒平均尺寸约0．2μm，且微晶粒沿a轴方向优先生长；析晶优先从玻璃表面开始向内部进行，形成晶化层—玻璃—晶化层的三元“夹心”结构．该玻璃陶瓷具有良好的光学性能，在1．064μm调QNd:YAG强激光作用下观察到了样品倍频信号的产生（SHG）．     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。