Investigation of Centreline Segregation and Centreline Porosity in CC ‐ Slabs

Improvements of solidification processing in conventional or near net shape casting depend on sophisticated methods of macroscopic examination of central unsoundness and inhomogeneity of the cast material. As long as remarkable deviations referring to the quality features exist between the slab centre and the bulk material such methods should be looked after. Two semi‐macroscopic methods of segregation analysis are discussed in this paper: firstly, the potential of the emission spectral analysis combined with sectioning of a sample and secondly, the computer aided micro‐probe analysis. Both methods are restricted to small local areas. The proneness of elements and steel grades with respect to micro‐ and macrosegregation as well as distribution‐ and segregation coefficients are determined. The effect of a diffusion anneal on homogenisation of segregation is studied. Last not least the precipitation of sulphides, phosphides or carbonitrides is estimated. Ultrasonic detection of the central unsoundness of conventional slabs or thin slabs is a new approach towards a quantitative macroscopic examination. The sample size is 400 mm x 300 mm x 30 mm. To achieve a low ultrasonic noise using a 5 MHz‐transducer the samples are heat treated for grain refinement. “Dog bone porosity”, macroscopic topographical misfit between the upper and lower solidifying shells, periodical corner cracks or systematic transverse centre cracks are detected. Obviously, segregations do not reflect the ultrasonic beam. However, it can be presumed that an interrelation exists between porosity and segregation, although these might be locally apart from each other. This new ultrasonic test of the central unsoundness of continuous cast (c.c.) slabs gives valuable arguments to machine builders and maintenance people to decide on the right concepts for strand guidance, support rollers and secondary cooling. Soft reduction can be optimized and variations in casting speed counteracted by dynamic means. R&D service of this kind can help steelmakers when decisions are impending to build new casting machines or revamp old ones.     

太钢不锈冷轧工程防腐蚀施工技术

防腐蚀施工工艺掌握的好坏，直接影响到工程投入生产后的使用寿命，为保证工程质量，以太钢不锈冷轧改造工程冷线防腐为例，对其常发生的质量通病进行认真分析，总结出一套行之有效的施工技术。     

石英玻璃结构调整和二阶非线性光学效应产生机制的理论研究

从非谐振动理论观点出发．考虑到玻璃在外场及加热条件下结构取向调整和弛豫，对外部静电场和加热的温度及加热时间对其信频光产生的影响进行了探讨性理论研究，结果较好地解释了有关实验现象。     

钢中非金属夹杂物显微评级方法的定量化探讨

应用ＩＢＡＳ系列图像分析系统，对建立一套与国家标准ＧＢ１０５６１─８９兼容的钢中非金属夹杂物显微评级方法的自动化和定量化标准作了可行性分析，结果表明建立这套标准是切实可行的。     

单轴-平面W型复合锶铁氧体的制备及其吸波特性研究

用草酸盐共沉淀和微量掺杂法研制六角晶系W型Ni,Zn,Co,Al多元复合锶铁氧体，通过调节Ni2W同Co2W的摩尔比例，可使该种铁氧体易磁化方向从C单轴型向垂于C轴的平面型转化，控制置换锶铁氧体中部分Fe3 的微量掺杂Al3 ，可以调整4πMs值，提高磁晶各向异性场，测试分析了5种不同含Co量的W型复合锶铁氧体粉料涂层的吸波特性，发现其自然共振吸收峰随Co含量增加向低频方向偏移，最高吸收峰可达32．8dB，是适用于电子隐形技术的高品位的微波吸收剂。     

特征提取在硅内部微/纳米级体缺陷检测中的应用

提出了一种利用特征提取来对硅中微/纳米级体缺陷的激光散射图样进行分析,以获得缺陷大小信息的分析方法.给出了该方法中第一特征值和第二特征值的定义,指出通过所提出的第一特征值及第二特征值即可迅速地判断出缺陷的大小量级所在.这种分析方法具有分析速度快,在体缺陷小于1μm时分辨率高,且可使系统实现自动化等优点.     

A simple modification to the LKB 7800 series Knifemaker and a balanced-break method to prepare glass knives for cryosectioning

A novel method of using the LKB 7800 series Knifemaker to produce glass knives using a balanced break is described. The method produces knives of sufficient quality to section aldehyde-fixed, sucrose-cryoprotected, frozen biological material in a cooled cryochamber of an ultramicrotome. The modifications to the Knifemaker are minimal and, if required, the machine can be returned easily to its normal state after use.     

Entropy,Free Volume,and Cooperative Relaxation

The high frequency end of the relaxation spectrum for polymer molecules involves the rotation of the segmental bonds. This fast relaxation process, however, cannot take place easily in the condensed state crowded by the densely packed conformers, necessitating the slower cooperatively synchronous relaxation. As the temperature is lowered, the domain of cooperativity grows towards the infinite size at the Kauzmann zero entropy temperature, though actually the system deviates from the equilibrium as the glass transition intervenes typically at 50 K above that temperature. The excess enthalpy and entropy drop faster than predicted by the rotational isomeric states which would reach zero only at 0 K. The real ΔC_P is greater than that of the RIS value. The actual volume in excess of the crystalline lattice volume, however, points towards zero at 0 K. Thus, a polymer with higher T_g typically exhibits a lower density and modulus in the glassy state. Since the configurational entropy associated with the free volume is proportional to the logarithm of the latter, the Kauzmann temperature can be scaled by ln M, where M is the algebraic average of the conformer molecular weight. The temperature dependence of the most dominant, i.e., the largest equilibrium domain size will result in the Adam-Gibbs and Vogel equations for the characteristic relaxation time. The cooperative domain distribution leads to the relaxation spectrum that follows a power law. The relationship between the characteristic relaxation time and the rate of physical aging is derived.     

彩色PDP用玻璃基板

本文讨论了彩色ＰＤＰ现用钠钙玻璃的热稳定性，指出由于这种玻璃在热处理过程中易变形和收缩，因而不适合作大面积彩色ＰＤＰ基板材料，介绍了彩色ＰＤＰ基板玻璃的制造方法和特点。最后介绍了日本旭硝子公司和美国康宁公司各自为彩色ＰＤＰ新开发的玻璃基板材料ＰＤ２００和ＣＳ２５。     

磷酸盐激光玻璃中铂颗粒密度与氧化还原平衡关系的研究

用吸收光谱法研究了Ｒ２Ｏ—ＢａＯ—Ｐ２Ｏ５系统磷酸盐激光玻璃中铂颗粒密度与铭的氧化还原平衡的关系。结果表明，玻璃中铂颗粒密度随平衡向右移动而减小；玻璃中平衡随熔炼气氛中氧分压增大、熔炼温度升高而向右移动，当足够大时，铂颗粒不能形成。