Influence of interfacial strength on the fracture toughness of glass-ceramic matrix composites

Nine kinds of glass-ceramic matrix composites with different compositions and interfacial strength (τ _s) were prepared. The influence of τ _s on the fracture toughness(K _1c) of composites was studied. It was discoved that, for the system no chemical reaction taking place at the interface, K _1c increased proportionally with τ _s increasing at the first stage, then decreased when τ _s reached a certain value. According to this result, a model of relationship between τ _s, thermal mismatch (Δα _r) and K _1c was built up. If a chemical reaction took place and a new phase was formed in the interface, the K _1c of composite was effected by the combination of τ _s, chemical bonding, radial interfacial stress and other factors. Project supported by the National Natural Science Foundation of China Synopsis of the first author Wang Lingsen, professor, born in 1938, current research field: special ceramic and ceramic matrix composite, etc.     

论印欧语系原始词根的排列组合及语义特征

本文运用语言学理论对印欧语系的原始词根进行了全新的分析和综合，揭示了词根字母排列组合的内在规律、首位字母的宏观倾向性语义及词根语义的相互关系。这有助于加深对印欧语系原始母语的了解，促进对其所派生的现代相关语言的研究。     

预烧淬火速度对NiCuZn铁氧体性能的影响

采用传统的氧化物法制备NiCuZn铁氧体,预烧保温后采用了三种不同方式冷却,研究了冷却速度对材料微观结构和磁性能的影响。发现随着冷却速度的加快,可获得更好微观结构、更高起始磁导率、更低损耗、更高烧结密度之低温共烧材料。     

Optimizing the results of pseudo-inverse simulation of the dynamics of space-time distributed processes

The analysis of root-mean-square simulation of the initial boundary-value problems of the dynamics of distributed-parameter systems is continued. The authors formulate and solve minimization problems for the simulation errors by optimizing observations of the initial and boundary conditions and by selecting reference points for simulation functions.Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 45–57, September–October 2004.     

磨粉机轧辊失效机理及提高使用寿命的途径

本文探讨了磨辊的磨损失效机理。用扫描电镜分析磨粉机轧辊的磨面和磨屑,提供了疲劳脱落和不均匀磨损的证据。侧磨试样发现磨辊亚表层显微裂纹,珠光体抑制渗碳体中裂纹的扩展。 经变质处理,在硬度变化不大情况下提高铸铁冲击韧性。磨损试验表明,相对耐磨性随韧性提高而提高,硬度与相对耐磨性并非线性关系,硬度与韧性相匹配的材料具有良好的抗磨性,装机试验比原材料磨辊使用寿命提高30％。     

抗层状撕裂钢16MnR—Z25的研制

舞钢首次为需方提供的１６ＭｎＲ－Ｚ２５钢板用于连铸机设备，通过试制和生产，舞钢已向需方提供了２０～１２０ｍｍ九个厚度规格的１６ＭｎＲ－Ｚ２５钢板，对该钢的研制与生产，说明所制定的工艺是可行的，在严格执行生产工艺的前提下，钢板质量，各项性能均满足技术条件的要求，并有一定的富裕量。     

Effect of niobium on thermal stability and impact toughness of Nd-Fe-B magnets with ultra-high intrinsic coercivity

The effects of Nb on the thermal stability and impact toughness of ultra-high intrinsic coercivity of Nd-Fe-B magnets were investigated.The results showed that the addition of Nb could improve the thermal stability,and obviously increased the impact toughness of sintered Nd-Fe-B magnets.The optimum thermal stability of sintered Nd-Fe-B magnets was obtained when the content of Nb was 1.0 at.%.The maximum impact toughness of sintered Nd-Fe-B magnets was obtained when the content of Nb was 1.5 at.%,but the magnetic properties of sintered Nd-Fe-B magnets drastically deteriorated when the content of Nb increased from 1.0 at.% to 1.5 at.%.The microstructure showed that overfull Nb addition made many ultra-fine grains get together,which led to the density of sintered Nd-Fe-B magnets decline and drastically deteriorated the magnetic properties of sintered Nd-Fe-B magnets.     

单试样三点柔度法测金属材料JR曲线及其条件起裂值

在单试样卸载柔度法及单试样三曲线法基础上,提出了一种更简便的测定金属材料ＪＲ曲线及其条件起裂值的单试样三点预先度法,并用该方法测定了１Ｃｒ１／２Ｍｏ钢、１６ＭｎＲ风和ＷＣＦ６２钢的ＪＲ曲线及其条件起裂值,与标准的多试样法相比,误差均在工程许可范围内。     

人工水晶的压痕断裂行为及其 K_(1c)测量

藉助于声发射技术,研究了在 Vickers 钻石压头作用下人工水晶的压痕断裂行为。压头对角线与晶体试样的相对取向是,使得水晶Ⅰ和水晶Ⅱ的压痕诱发径向/中位断裂,分别沿着(10(?)0)/(1(?)10)和(11(?)0/(1(?)00)晶面对发展。压痕断裂过程中的声发射特征表明,除了随着压痕特征参数的发展所引起的准静态—声发射外,有三个相互独立的,与径向/中位裂纹的成核、径向/中位裂纹突入试样表面、以及裂纹分岔或侧向裂纹萌生等过程相关的声发射效应。以 Vickers 压痕技术测得 K_(c2)的结果与以一般力学法及 Knoop 压痕技术的测试结果作了比较。断裂韧性与晶体学取向的关系亦作了分析。实验表明,水晶Ⅰ和水晶Ⅱ具有相同的 K_(1c)值。其原因是,两种试样的径向/中位裂纹实际上沿着同样的{1100}/{1120}晶面对扩展。至于从缺口梁法或 Knoop 压痕技术得到的 K_(1c)值,由于水晶Ⅰ和水晶Ⅱ的主裂纹分别沿着(1(?)10)和(1(?)00)晶面扩展;它们的 K_(1c)值与断裂能随着晶体学取向而变有关,因而也就各不相同。