Chemische Zusammensetzung und Mikrostruktur polymerabgeleiteter Gläser und Keramiken im System Si–C–O. Teil 2: Charakterisierung der Gefügeausbildung mittels hochauflösender Durchstrahlungselektronenmikroskopie und Feinbereichsbeugung

Chemical Composition and Microstructure of Polymer‐Derived Glasses and Ceramics in the Si–C–O System. Part 2: Characterization of microstructure formation by means of high‐resolution transmission electron microscopy and selected area diffraction Liquid or solid silicone resins represent the economically most interesting class of organic precursors for the pyrolytic production of glass and ceramics materials on silicon basis. As dense, dimensionally stable components can be cost‐effectively achieved by admixing reactive filler powders, chemical composition and microstructure development of the polymer‐derived residues must be exactly known during thermal decomposition. Thus, in the present work, glasses and ceramics produced by pyrolysis of the model precursor polymethylsiloxane at temperatures from 525 to 1550 °C are investigated. In part 1, by means of analytical electron microscopy, the bonding state of silicon was determined on a nanometre scale and the phase separation of the metastable Si–C–O matrix into SiO₂, C and SiC was proved. The in‐situ crystallization could be considerably accelerated by adding fine‐grained powder of inert fillers, such as Al₂O₃ or SiC, which permits effective process control. In part 2, the microstructure is characterized by high‐resolution transmission electron microscopy and selected area diffraction. Turbostratic carbon and cubic β‐SiC precipitate as crystallization products. Theses phases are embedded in an amorphous matrix. Inert fillers reduce the crystallization temperature by several hundred °C. In this case, the polymer‐derived Si–C–O material acts as a binding agent between the powder particles. Reaction layer formation does not occur. On the investigated pyrolysis conditions, no crystallization of SiO₂ was observed.     

激光熔覆专用铁基合金粉末的研究进展

指出了目前防止熔覆层开裂所采取的主要措施中存在的问题,阐述了激光熔覆和热喷涂对于所用合金粉末性能要求之异同,评述了激光熔覆专用铁基合金粉末的研制现状,提出了成分与组织设计的新思想。     

Fatigue limit evaluation of notches,small cracks and defects: an engineering approach

In this paper, the average stress method for the fatigue limit evaluation of stress raising geometrical features is revised and extended. In particular, an analytical close‐form approach was used and the linear elastic stress equations were modified by taking into account the effect of nominal stress on the local stress distribution. Hence, the average tangential stress was correctly evaluated over a distance of 2a₀, where a₀ was El Haddad's short crack constant, for long and small notches as well as for crack‐like notches. When this model is applied to a wide range of geometrical features subjected to mode I fatigue loading, the classical shape of the curves of the Kitagawa–Takahashi diagram was obtained for changes in crack‐like notch size. Similarly, notch sensitivity was estimated by reducing the notch tip radius. The accuracy of the proposed method in predicting fatigue limits was then checked by using experimental data taken from the literature and generated on testing specimens weakened by rounded and sharp notches as well as by small artificial defects.     

土石过水围堰过水期最不利工况及其流量确定

本文系统分析了影响土石过水围堰溢流工况的主要因素，提出衡量最不利工况的指标和确定员不利流量的方法，为土石过水围堰堰体下游护坡结构及消能防冲设施设计提供了理论依据。通过理论计算结果与模型试验现场观测资料数据对比分析，说明提出的过水期最不利流量判别方法是符合实际情况的。     

大功率CO2激光器脉冲电源研究

本文论述了直流高压与高频脉冲电源相叠加，构成高频、高压脉冲电源，并使其对CO2激光器进行放电实验，研究了同条件下的放电参数与功率。     

滚动式冷床在高钢级油管生产线中的应用

根据石油开采业对石油机械产品的需求 ,利用机械理论基础知识 ,通过实践设计 ,提出了对几何尺寸长的金属管类进行调质处理后的均匀冷却方法 ,以满足其性能要求。     

高含沙水深井泵站的综合治理

对攀钢动力厂深井泵站自投产以来出现的主要问题及其解决方案，方法进行了分析和论述。     

低温高速离心泵的研制与应用

阐述了适合于输送低温介质的高速离心泵的水力设计和结构设计方法，结构上采有长，中，短叶片相间的复合叶轮及双密封结构，理论上采用以效率为目标函数的优化水力设计方法，保证了低温高速离心泵具有很好的工人可靠性和优越的性能指标。     

SJ—YⅡ—5型高爆速高威力水胶炸药的研制

文章简要分析了我国目前在中硬岩石爆破中工业炸药的使用情况，介绍了山西兴安化学材料厂新研制的一种适用于硬岩爆破的高爆速、高威力水胶炸药新品种，对其性能、爆破效果、经济实用性和安全性等进行了阐述。     

HDPE／PS／HDPE－g－PS合金的相容性和力学性能研究

用自制接枝共聚物ＧＲ－Ⅰ、ＧＲ－Ⅱ相容剂研究其对ＨＤＰＥ／ＰＳ共混物相容性和力学性能的影响。通过ＳＥＭ、ＤＭＡ、ＤＳＣ和力学性能测试表征，表明在ＨＤＰＥ／ＰＳ共混中加入这些相容剂其相容性和力学性能有一定提高