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991.
《Ceramics International》2017,43(6):5283-5291
Cu-SiC composites are very promising materials which have high thermal and electrical conductivity and may find many applications. Unfortunately, the main disadvantage of these materials is the dissolution of silicon in copper at elevated temperature, which significantly reduces their properties. In order to overcome this problem particles can be coated with a protective material before sintering. In this paper– the influence of three different metallic coatings on bonding strength were investigated. SiC particles were coated with tungsten, chromium or titanium. As reference a material with uncoated particles was prepared. The experiments were carried out with the use of microtensile tester. The highest increase in strength was observed in the case of chromium coating. On the other hand, the titanium coating, which was of very poor quality, decrease the bonding strength in comparison with uncoated particles. Furthermore, scanning electron and optical microscopes were used to determine the mechanism of debonding. 相似文献
992.
《大分子材料与工程》2017,302(5)
Failure of dental composite restorations is primarily due to recurrent decay at the tooth–composite interface. At this interface, the adhesive and its bond with dentin is the barrier between the restored tooth and the oral environment. In vivo degradation of the bond formed at the adhesive/dentin (a/d) interface follows a cascade of events leading to weakening of the composite restoration. Here, a peptide‐based approach is developed to mineralize deficient dentin matrices at the a/d interface. Peptides that have an inherent capacity to self‐assemble on dentin and to induce calcium–phosphate remineralization are anchored at the interface. Distribution of adhesive, collagen, and mineral is analyzed using micro‐Raman spectroscopy and fluorescence microscopy. The analysis demonstrates remineralization of the deficient dentin matrices achieved throughout the interface with homogeneous distribution of mineral. The peptide‐based remineralization demonstrated here can be an enabling technology to design integrated biomaterial–tissue interfaces.
993.
994.
Large confined space has high incidence of fires, which seriously threatens the safety of people working there. Understanding the distribution of smoke in such large space is critical to fire development prediction and smoke control. Three improved methods for the stratification interface prediction of fire smoke are developed, including of improved intra-variance, integral ratio and N-percentage methods. In these methods, the interface height is determined by the vertical temperature distribution based on a three-layer smoke zone model, which is an improvement of a two-layer zone model. Thereafter, the three improved methods are applied to several typical fire cases simulated CFD to predict the smoke interface, and their applicability and reliability are verified by comparison of the smoke stratification results with the filed simulation results. Results show that the three improved methods can effectively determine the location of the three-layer zone model's interface, and they have the ability to predict smoke interface for fires with different fire source types and ventilation conditions. 相似文献
995.
Soumya Ghosh Chowdhury Jagannath Chanda Sreedip Ghosh Koushik Banerjee Shib Shankar Banerjee Amit Das Prasenjit Ghosh Sanjay Kr. Bhattacharyya Rabindra Mukhopadhyay 《Polymer Engineering and Science》2020,60(8):1973-1983
Proficiency on underlying mechanism of rubber-metal adhesion has been increased significantly in the last few decades. Researchers have investigated the effect of various ingredients, such as hexamethoxymethyl melamine, resorcinol, cobalt stearate, and silica, on rubber-metal interface. The role of each ingredient on rubber-metal interfacial adhesion is still a subject of scrutiny. In this article, a typical belt skim compound of truck radial tire is selected and the effect of each adhesive ingredient on adhesion strength is explored. Out of these ingredients, the effect of cobalt stearate is found noteworthy. It has improved adhesion strength by 12% (without aging) and by 11% (humid-aged), respectively, over control compound. For detailed understanding of the effect of cobalt stearate on adhesion, scanning electron microscopy and energy dispersive spectroscopy are utilized to ascertain the rubber coverage and distribution of elements. X-ray photoelectron spectroscopy results helped us to understand the impact of CuXS layer depth on rubber-metal adhesion. The depth profile of the CuXS layer was found to be one of the dominant factors of rubber-metal adhesion retention. Thus, this study has made an attempt to find the impact of different adhesive ingredients on the formation of CuXS layer depth at rubber-metal interface and establish a correlation with adhesion strength simultaneously. 相似文献
996.
Weibing Guo Haitao Xue Xin Wei Xiaoming Zhang 《International Journal of Applied Ceramic Technology》2020,17(3):1286-1292
Ti element is an important active element in brazing Zirconia ceramic (ZrO2) ceramic. Therefore, the interface bonding mechanism of Ti and ZrO2 was studied by using first principles calculation. Two kinds of interfaces with different termination and stacking sequence were established, and the interfacial bonding mechanism was studied using work of adhesion (Wad), electronic behavior and interface energy. The results show that in the O-terminated interface, Ti and O form a strong ion-covalent bond at the interface, and the Wad can reach 13.61 J/m2. In the Zr-terminated interface, Ti and Zr form a metal-covalent bond, and the Wad is 5.56 J/m2. At a temperature of 1123K, when the lnPO2 is larger than e−17, the O-rich interface is more stable in thermodynamics. Therefore, under the experimental condition, the interface tends to form Ti-O compounds when ZrO2 is brazed using Ag(Ti) filler metal. 相似文献
997.
Jake E. Doiron Dr. Christina A. Le Dr. John Bacsa Prof. Gary W. Breton Prof. Kenneth L. Martin Prof. Stephen G. Aller Prof. Mark Turlington 《ChemMedChem》2020,15(18):1720-1730
Although the 1,2,3-triazole is a commonly used amide bioisostere in medicinal chemistry, the structural implications of this replacement have not been fully studied. Employing X-ray crystallography and computational studies, we report the spatial and electronic consequences of replacing an amide with the triazole in analogues of cystic fibrosis drugs in the VX-770 and VX-809 series. Crystallographic analyses quantify subtle differences in the relative positions and conformational preferences of the R1 and R2 substituents attached to the amide and triazole bioisosteres. Computational studies derived from the X-ray data highlight the improved hydrogen bonding donor and acceptor capabilities of the amide in comparison to the triazole. This analysis of the spatial and electronic differences between the amide and 1,2,3-triazole will inform medicinal chemists as they consider using the triazole as an amide bioisostere. 相似文献
998.
Pengju Chen Peng Xiao Zhuan Li Ling Pan Jinwei Li Zeyan Liu Dongmei Pu Yang Li 《Journal of the American Ceramic Society》2020,103(1):82-93
Mullite coating, SiC whiskers toughened mullite coating (SiCw-mullite), and cristobalite aluminum phosphate (c-AlPO4) particle modified SiCw-mullite coating (c-AlPO4-SiCw-mullite) were prepared on SiC coated C/SiC composites using a novel sol-gel method combined with air spraying. Results show that molten SiO2 formed by the oxidation of SiC whiskers and molten c-AlPO4 improved the bonding strength between mullite outer coating and SiC–C/SiC composites due to their high-temperature bonding properties. The bonding strength between mullite, SiCw-mullite, c-AlPO4-SiCw-mullite outer coatings and SiC–C/SiC composites were 2.41, 4.31, and 7.38 MPa, respectively. After 48 thermal cycles between 1773 K and room temperature, the weight loss of mullite/SiC coating coated C/SiC composites was up to 11.61%, while the weight losses of SiCw-mullite/SiC and c-AlPO4-SiCw-mullite/SiC coatings coated C/SiC composites were reduced to 7.40% and 5.12%, respectively. The addition of appropriate SiC whiskers can considerably improve the thermal shock resistance of mullite coating owing to their excellent mechanical properties at high temperature. In addition, c-AlPO4 particles can further improve the thermal shock resistance of SiCw-mullite coating due to their high-temperature bonding and sealing properties. No obvious micro-pores and cracks were observed on the surface of c-AlPO4-SiCw-mullite coating after 48 thermal cycles due to timely healing effect by formation of secondary mullite. 相似文献
999.
尹臣慈 《南方冶金学院学报》1990,11(4):73-76
本文介绍在APPLE—Ⅱ机上,采用汇编语言程序,按磁盘道段直接存取信息,能充分利用外存容量,提高程序运行速度,并解决了计算机绘图中,运行大程序数据传递和复盖的困难. 相似文献
1000.
本文介绍了 MCS—48系列单片机与 TP—801P 微型打印机的一种接口方法,给出了硬件结构和程序框图,提供了微型打印机作为单片机硬考贝输出设备的途径。 相似文献