颗粒表面改性法制备PTC粉体的研究

本文介绍了一种通过液相颗粒表面改性技术添加二次掺杂物来制备ＰＴＣ粉体的新方法。即将烧结助熔剂Ａｌ２Ｏ３，ＳｉＯ２以及受主杂质ＭｎＯ采用溶液形式，包裹在ＢａＴｉＯ３基粉体颗粒表面进行改性，由此可以得到二次掺杂物Ａｌ２Ｏ３、ＳｉＯ２和ＭｎＯ分布均匀的ＰＴＣ粉体。     

碳化硅加热元件的电性能和使用

本文介绍碳化硅加热元件的电特性、表面负荷以及工作气氛对它的影响，并对它设计和使用要点举例予以说明。     

Adhesion Mechanisms of Polyurethanes to Glass Surfaces. III. Investigation of Possible Physico-Chemical Interactions at the Interphase

Surface free energies of polyurethanes made from toluene diisocyanate and 1, 4 butanediol-based hard segments and caprolactone polyol-based soft segments were calculated using additive functions. Good agreement was found between the calculated values based on additive functions and the calculated values based on contact angle measurements. The phase-separated polyurethanes were found to have a higher polar surface free energy component (γ^P). This was linked to the preferential segregation of butanediol/butanediol-derived moieties to the polyurethane surfaces due to phase separation. The adhesion values of these polyurethanes to soda-lime glass were correlated with their respective γ^P values and a linear relationship was found. It was also shown that the adhesion values of the low γ^P polyurethanes improved substantially when the glass surfaces were coated with a thin layer of butanediol prior to the bonding. The modulus of the interphase region rich in butanediol was evaluated. Although a modulus increase was found at the interface, this increase was found to play a secondary role in the adhesion. The chemical interactions at the polyurethane/glass interphase were investigated by pre-treating the glass surfaces with methyl-trimethoxysilane and trimethylchlorosilane prior to adhesion testing. The adhesion data showed no significant difference between the uncoated and the silane-treated glass substrates. Based on this experimental evidence, the possibility of any covalent or ionic bonding at the polyurethane/glass interphase was assumed negligible. It was determined that the mechanism of adhesion between the polyurethanes and the glass surface could be through the formation of an interphase region in which hydrogen bonding between the butanediol-rich interphase region and the hydroxylated glass surface plays a key role.     

The multi-structure of oxidized-reduced tungsten carbide surface(s)

The XPS of bulk tungsten carbide, partially oxidized WC surfaces at 373 and 573 K as well as tungsten trioxide have been reported. Bulk WC has been prepared from WO₃ as a starting material in a mixture of CH₄ (20%) and H₂ (80%) at 1150 K for 4 h, while partially oxidized WC surfaces were prepared by oxygen chemisorption on a clean WC surface at 200 K, then the temperatures were raised to 373 and 573 K respectively. The XPS of a freshly prepared WC reveals the presence of a small amount of WO₃ on the surface and a slightly higher concentration in the bulk. The oxygen-exposed fresh WC surfaces and surfaces treated at temperatures higher than 373 K show the presence of WO₃ in a considerable quantity depending on the length and the treatment temperature. Ar⁺ bombardment of this partially oxidized surface reduces WO₃ to WO₂ and W(0), while WC is partially reduced to W(0). Isomerization reactions of alkanes on oxygen-exposed WC surface occurs in reality on a composite surface structure containing WC, WO₃, WO₂ and elemental W(0).     

多层住宅砖混房屋设计中两点问题的探讨

浅议多层住宅砖混房屋中构造柱的作用及设置方法；探讨了砖混结构墙下条形基础底面积重复利用问题及其解决方法。     

如何提高干式喷射彩色混凝土的观感质量

从彩色混凝土喷射施工的特点出发，结合工程实例，分析了影响喷射彩色混凝土观感质量的原因和解决方法。指出彩色混凝土喷射工艺可以有效地解决大面积混凝土边坡与周围环境的协调性问题。     

Nondestructive evaluation of pavements using spectral analysis of surface waves in the frequency wave-number domain

The potential of using Spectral analysis of surface waves (SASW) for nondestructive testing of pavement and soil sites has been demonstrated in several publications. The usual SASW field testing and data analysis procedures and the assumption of a single propagation mode yield accurate results when there are no sharp changes in the stiffness of the site with depth. When this is not the case, however, difficulties arise in the interpretation of experimental data due to the participation of more than one mode in the wave field. In an earlier study, the multiple filter/crosscorrelation technique was suggested for analyzing multi-mode SASW signals. This technique, however, may not yield accurate results when propagation modes are closely spaced. A more general method using spectral analysis in the frequency wave-number domain is presented in this paper. Formulas are presented for determining a reasonably small number of surface measurements, and the accuracy of this method in resolving experimental dispersion curves is demonstrated for a pavement site.     

溶胶－凝胶二氧化硅驻极体薄膜的物理化学改性

实验研究了由溶胶－凝胶法制备二氧化硅驻极体薄膜的工艺。用红外透射谱、扫描电子显微镜以及驻极体等温表面电位测量和热刺激放电等实验考察了热处理和化学表面修正两个关键工艺对溶胶－凝胶二氧化硅样品驻极体性能的影响。结果表明经过高温条件下一定时间的热处理和化学表面修正，可以制备出性能优良的驻极体薄膜     

钻井泵阀箱密封面CO2堆焊试验研究及应用

介绍了用CO_2堆焊35CrMo钢钻井泵阀箱密封面磨损修复工作,通过试验表明,采用Φ1.2mm的H08Mn2Si焊丝,以短路过渡CO_2焊法施焊,可以获得致密、耐磨的堆焊金属层。该法已成功地用于生产,取得了良好的经济效益。