Deformational Properties of Polymer Concrete during Long-Term Exposure to Water

Changes in the elastic and viscoelastic (creep) characteristics of polymer concrete and its structural components (polyester resin, unfilled or filled with diabase flour) during a long-term exposure to water at 20°C were studied. Modeling the structural changes in polymer concrete with time showed an increase in the relative volume content of pores filled with water and a decrease in that of unfilled pores. Based on the free-volume concept and the data on swelling due to moistening and shrinkage due to physical aging of the binder, a rather accurate estimate of the time-moisture reduction function for polymer concrete was obtained. The function was found to be nonmonotonic: the interval of increase was followed by an interval of decrease.     

Processing of mineral and technogeneous raw materials by carbothermal reduction

Current studies dealing with the preparation of promising materials (most of all, ceramics) by carbothermal reduction (CR) of mineral and technogeneous raw materials is surveyed. Attention is concentrated on the mechanisms and kinetics of chemical reactions occurring during the CR process and on the effects of varying some factors during the reduction (temperature, duration of annealing, composition of the gas phase, ratio of the components, density of the blend,etc.) on the compositions and properties of the final products. Ways of optimizing particular technological schemes for the production of new materials by the CR method are discussed. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 233–245, February, 1997.     

Laser cutting of thick ceramic tile

This paper details developments in the CO₂ laser cutting of thick ceramic tiles, that is thicknesses of 8.5 mm and 9.2 mm. These tiles were cut at a combination of different cutting speeds to determine the necessary cutting parameters for various tile geometries. Different cutting modes were used in conjunction with different cutting speeds to investigate cut quality after laser processing. The work also looked into the effects on cutting through using various shield gases. Multipass cutting and underwater cutting were performed to examine their effects on thermal load during processing.     

光纤连接器

介绍了光纤连接器的结构、端面形状、技术指标要求以及近几年发展起来的新型光纤连接器。对光纤连接器的关键技术———氧化锆陶瓷 (PSZ)插针体的制造进行了详细的分析。结果表明 ,生产陶瓷插针的设备和工艺相对比较复杂 ,一次性的固定投入较多 ,只有达到一定的生产规模才能产生效益     

激光干涉法测压电陶瓷的压电常数d31

介绍迈克尔逊干涉仪原理在测微小位移中的应用。确定一种锆钛酸铅镧压电陶瓷的压电常数ｄ３１，得到了一种测ｄ３１的可行可靠的新方法。     

Determination of photoelectron attenuation lengths in calcium phosphate ceramic films using XPS and RBS

Calcium phosphate (CaP) coatings are used to improve the biological performance of an implant. A technique that is often used to measure the composition of this material is XPS. When extremely thin coatings are measured, for example to study the interface between CaP and a substrate, the quantification of the XPS results is complicated by the varying attenuation lengths (ALs) of the photoelectrons at different energies. To correct for this, AL data are needed. In this work we measured these ALs by comparing XPS yields with the coating coverage (as measured by Rutherford backscattering spectrometry). We were able to determine the AL for several calcium and phosphorus peaks. Determination of the oxygen ALs was not possible owing to diffusion of oxygen into the polymeric substrates. For the peaks that are most often used for quantification of XPS yields (the Ca 2p and the P 2p peak), we found ALs of 21.8 × 10¹⁵ atoms cm^?2 and 26.8 × 10¹⁵ atoms cm^?2, respectively. Concentration profiles near the interface, growth mode and interfacial roughness appeared to have no measurable effect on the measured ALs. For the ALs, an energy dependence with an exponent of 0.55 was found. The measured ALs are best predicted by the empirical CS1 equation of Cumpson and Seah. Copyright © 2003 John Wiley & Sons, Ltd.     

An elastic micro-structural continuous damage model

The paper formulates a micro-structural continuous damage theory describing an anisotropic damage field. The model can be reduced to some of the major models well known at present, and the numerical analyses are compared with the experimental data of the concrete specimen under uniaxial tension and compression.     

钢筋混凝土箱梁开裂后剪力滞效应的研究

本文用级数分析方法分析了钢筋混凝土箱梁开裂后的剪力滞效应,推得了剪滞应力公式.根据应力公式,本文还探讨了剪力滞效应随配筋率ρ等的变化情况.     

Li掺杂对ZnO陶瓷结构与电学性能的影响

研究了用传统方法在1200～1400℃烧结的ZnO陶瓷，以及用放电等离子体烧结(SPS)方法烧结的ZnO陶瓷的结构特征与电学性能。以ZnO为基添加了不同浓度的LiOH，制备了不同Li掺杂浓度的ZnO陶瓷。研究了掺杂、烧结温度，以及烧结方法等因素对ZnO基陶瓷的微观结构、电学性能的影响。实验表明，用传统方法烧结时，ZnO在烧结温度低于1400℃的情况下难以成瓷，而放电等离子体烧结(SPS)方法可以显著降低烧结温度。ZnO陶瓷的晶粒大小。密度随着烧结温度的增大而增大。在同样的烧结温度下，LiOH含量越大，ZnO基陶瓷的电阻率越大。     

Shaping and Mechanical Reinforcement of Silica Aerogel Biocatalysts with Ceramic Fiber Felts

The synthesis of silica aerogels reinforced with either carbon or silica fibre felts and which encapsulate the lipase PS of Amano (LPS AB025407) obtained from Burkholderia cepacia is described. The materials were further shaped by moulding them in Teflon^® tubes. The silica aerogels were synthesized with various ratios of hydrophobic groups and dried according to the supercritical CO₂ method. Both types of reinforcements improve the catalytic activity of the material per mass of lipase. The fibre felts reinforcements also enable the encapsulation of higher concentrations of lipase. The materials were shaped into small moulded monoliths, which were readily washed and recycled without significant mechanical deterioration or loss of catalytic activity. In addition, hydrophobic carbon felts reinforce more efficiently silica aerogels that incorporate a high ratio of hydrophobic groups, while silica felts strengthen those aerogels that carry a low proportion of hydrophobic groups.