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991.
M. V. Tsodikov N. I. Laguntsov M. I. Magsumov P. V. Spiridonov O. V. Bukhtenko T. N. Zhdanova V. V. Teplyakov 《Russian Chemical Bulletin》2004,53(12):2723-2729
Ceramic and cermet membranes containing catalytic coatings in the internal volume of their channels were obtained. A relationship between the permeability and kinetic regularities of CO oxidation describing the transmembrane flow of gases was studied. The pre-exponential factor and apparent activation energy change as the loading of the membrane channels by the catalyst proceeds. The study of gas permeability through the membranes showed that the catalyst with a loose branched surface is distributed in the membrane microchannels. The reaction rate constant increases in parallel with an increase in the relative fraction of the catalyst surface. The CO oxidation rate is assumed to depend statistically on the number of active sites, which increases with filling of the membrane channels by the catalytic material.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2613–2619, December, 2004. 相似文献
992.
M. Vardelle C. Trassy A. Vardelle P. Fauchais 《Plasma Chemistry and Plasma Processing》1991,11(2):185-201
An experimental study of the vaporization of metallic and ceramic particles in a thermal do plasma jet has been initiated and two series of experiments have been performed: (1) measurement of the vapor concentration within the plasma jet by absorption spectroscopy. (2) Investigation of the vapor cloud surrounding a single particle in flight by emission spectroscopy. The temperature within this cloud is determined by the intensity ratio of two lines which are simultaneously measured. The cloud radius is deduced /torn measurement of the particle velocity by laser doppler anemometry, and the vapor concentration is calculated from the line intensity profile, once the temperature is known. Results on iron and alumina particles injected in argon or argon-hydrogen plasma jets are given and discussed. 相似文献
993.
994.
为减小压电陶瓷的迟滞非线性对系统跟踪精度的影响,该文采用经典的存在逆解析的PI迟滞模型对压电陶瓷的迟滞特性进行建模,将PI模型的逆模型用于压电陶瓷的前馈控制算法中,然后设计了神经元比例、积分、微分(PID)反馈控制算法,将前馈控制算法与神经元PID反馈控制算法结合得到了压电陶瓷的复合控制算法。将仅含前馈的控制算法和复合控制算法在压电陶瓷的控制器上执行,实验结果表明,仅含前馈的控制算法的跟踪误差为1.256 μm,而复合控制算法的跟踪误差仅为0.092 μm,该复合控制算法使跟踪精度提高了1.164 μm。 相似文献
995.
996.
997.
Despite good ability to improved biological affinity and activity of calcium phosphate (CP) ceramic to the surrounding host tissue when implanted, CP ceramic is capable to encourage direct bond with bone as their chemical compositions are similar to the mineral phase of bone. However, the low mechanical property of CP ceramic restricts use in load-bearing applications. Therefore, the primary aim of this study was to fabricate dense CP ceramic via used of microwave sintering analyze the microstructure and mechanical properties comparison to conventional ceramic sintering. The sintered specimens were characterized by their surface microstructure, density measurement and hardness test. The result demonstrated that the density and hardness values of sintered CP ceramic specimens by microwave sintering were higher than conventional sintering. The microstructures of CP ceramic microwave sintered specimens show also better microstructures (analyzed by FESEM technique), with fines grain size and the present of apatite layer growth on the surface when examined with SBF solution. It can be concluded that the microwave sintering enhanced better microstructure and mechanical properties of CP ceramic. 相似文献
998.
Hydrogen (H2) is regarded as an important energy carrier to achieve a clean and sustainable future. In particular, protonic ceramic cells (PCCs) as promising energy conversion technologies have received rapidly increasing attention for the production and use of H2, showing higher energy efficiencies at reduced temperatures than oxygen-ion-conducting counterparts. Nevertheless, the sluggish kinetics of air electrodes for oxygen reduction/evolution reactions has become one of the main obstacles to achieving high-efficiency PCCs. Therefore, the key point to realizing the commercialization of PCCs is the development of high-performance air electrodes. Particularly, perovskite-based nanocomposites received increasing interests as high-efficiency air electrodes for PCCs recently due to the synergistic effect and strong interaction between various phases with different functionalities at nanoscale. Herein, the advances of this area in 2020–2022 are mainly reviewed by highlighting the superiorities, design strategies, and remaining challenges of perovskite-based nanocomposites as air electrodes for PCCs at reduced temperatures. 相似文献
999.
Andrzej Malysa Joanna Wezgowiec Sylwia Orzeszek Wojciech Florjanski Marek Zietek Mieszko Wieckiewicz 《Molecules (Basel, Switzerland)》2021,26(5)
For long-term successful use of ceramic materials in dental procedures, it is necessary to ensure reliable bonding of restorations to dental substrates. This can be achieved by the application of a proper luting cement and through additional surface conditioning. The present systematic review summarizes the most up-to-date evidence on the use of different surface modification methods to enhance the bond strength of dental ceramics to the hard tissues of the teeth. The authors of the review searched the Web of Science, Scopus, and MEDLINE databases to identify relevant articles published between 1 January 2010 and 1 January 2020. A total of 4892 records were identified, and after screening, the full text of 159 articles was evaluated, which finally resulted in the inclusion of 19 studies. The available reports were found to be heterogeneous in terms of materials and methodology, and therefore, only within-studies comparison was performed instead of comparison between studies. A statistically significant difference in the bond strength between the samples treated with different methods of surface conditioning, or between conditioned and nonconditioned samples, was revealed by most of the studies. Predominantly, the studies showed that a combination of mechanical and chemical methods was the most effective way of enhancing bond strength. Artificial aging and luting cement were also identified as the factors significantly influencing bond strength. 相似文献
1000.
改进老练工艺是降低铝电解电容器漏电流的重要措施。采用脉冲电压老练能提高铝电解电容器阳极氧化膜的修补效率。用正交试验法快速找到脉冲电压老练中的充、放电时间等工艺参数 ,使产品漏电流常数 K降到 0 .3× 10 - 2 ~ 0 .3× 10 - 4 μA/ (V·μF)。 相似文献