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91.
T. L. Su L. C. Tsao S. Y. Chang T. H. Chuang 《Journal of Materials Engineering and Performance》2002,11(5):481-486
The interfacial reactions of liquid Sn and Sn-3.5Ag solders with Ag thick films are investigated in the temperature range
from 250–325 °C, and the morphology of intermetallic compounds formed after such soldering reactions is observed. In kinetics
analysis of the growths of intermetallic compounds, it was found that both Sn/Ag and Sn-3.5Ag/Ag reactions were interfacial-controlled,
and the growth rates for both cases were similar. The rate of Ag dissolution into liquid solder attendant on the formation
of interfacial intermetallic compounds after Sn/Ag reaction was about four times higher than that after Sn-3.5Ag/Ag reaction,
as evidenced by experimental results. 相似文献
92.
The surface modification of magnesium alloys (AZ31 and AZ91 HP) was studied by a high current pulsed electron beam(HCPEB). The results show that the cross-sectional microhardness of treated samples increases not only in the heat affected zone( HAZ), but also beyond HAZ, reaching over 250μm. This is due to the action of quasi-static thermal stress and the shock thermal stress wave with materials, which result in its fast deformation on the surface layer and so increases microhardness. For the AZ91HP alloy, a nearly complete dissolution of the intermetallic phase Mg17Al12 is observed, and a super-saturated solid solution forms on the re-melted surface, which is due to the solute trapping effect during the fast solidification process. Measurements on sliding wear show that wear resistance is improved by approximately 5.6 and 2.4 times for the AZ31 and AZ91HP respectively, as compared with as-received samples. 相似文献
93.
S. Y. Chang Y. T. Hung T. H. Chuang 《Journal of Materials Engineering and Performance》2003,12(2):123-127
Alumina ceramics were brazed to Inconel 600 and UMCo-50 superalloys at 900 °C for 10 min using an Sn10Ag4Ti active filler
metal. The brazing filler showed good wettability on alumina and superalloys. The flexural strengths were 69 and 57 MPa for
alumina/Inconel 600 and alumina/UMCo-50 joints, respectively. In both cases, the brazed specimens fractured along the Sn10Ag4Ti/superalloy
interfaces after four-point bending tests. Electron probe microanalysis (EPMA) elemental mapping revealed that the Ni of Inconel
600 and the Co of UMCo-50 dissolved into Sn10Ag4Ti filler metal, which serves to reinforce the weak Sn10Ag4Ti matrix. 相似文献
94.
The superplasticity of the Ti- 6Al- 6V- 2Sn alloy for different temperatures was evaluated by single-sheet free blowing. The
optimal superplastic temperature for the Ti- 6Al- 6V- 2Sn alloy was found to be 850 °C. Diffusion bonding of Ti- 6Al- 6V-
2Sn and 304 stainless steel was carried out in a vacuum. The interface of both bonded alloys was examined by EPMA. The concentration
profile of Ni exhibited a peak at the interlayer and a valley adjacent it, whereas that of Cr exhibited a peak where Ni showed
the valley. X- ray diffraction (XRD) analyses showed that the Fe
2
Ti, NiTi, and CrMn Intermetallic compounds and the Cr element formed at the interface. The thickness profiles of the blown
specimens were measured and compared with theoretical calculations. 相似文献
95.
用脉冲偏压电弧离子镀技术在玻璃基片上制备均匀透明的氧化钛薄膜,通过改变脉冲偏压幅值,考察其对氧化钛薄膜性能的影响。结果表明,沉积态薄膜为非晶态;脉冲偏压对薄膜性能有明显的影响。随偏压的增加,薄膜厚度、硬度和弹性模量均先增大后减小,前者峰值出现在-100-200V负偏压范围,后两者则在-150~250v范围:-300v偏压时的薄膜硬度最高;达到原子级表面光滑度,RRMs为0.113nm,薄膜折射率也最高,在λn=550nm达到已有报道的最高值2.51,此时薄膜具有最好的综合性能。文中对脉冲偏压对薄膜性能的影响机理也进行了分析。 相似文献
96.
Social networking sites (SNSs) are the most popular social platforms for developing personal networks. They provide multiple interactive functions for users to create and use large social networks. To determine why people exhibit ‘stickiness’ to SNSs, this study uses the uses and gratifications theory as an underlying structure and builds the research model with factors of motivational needs and interactivity. Our results showed that social needs, information needs, human–message interaction, and human–human interaction are crucial factors that affect the ‘stickiness’ of users to SNSs. The implications of these findings are presented in this paper. 相似文献
97.
无线多跳网络的分布式工作特点和无线传播介质的特性导致其面临着严峻的性能和安全性挑战,而为弥补以往研究过分依赖仿真分析的不足,基于路由代数与统一路由模型,设计并实现了多种设备的试验测试平台(testbed for high‐level analysis of wireless ad‐hoc routing design ,TH‐award)。该平台采用模块化架构设计了协议库、参数库和测试库,便于用户扩展无线路由协议,有效实现在同一平台上对协议性能与安全性的综合测试,保证了测试平台的可扩展性与兼容性;能以仿真、测试、试验等不同应用模式实现其测试功能,具有良好的适用性与开放性;平台具有分布式管理架构、路由测试引擎等相关设计,能有效实现配置管理、运行分析的自动化,具有很高的可管理性。基于该平台,实现了多种路由协议的快速设置与部署,基于多种场景测试验证了平台的有效性,该平台为研究各种无线路由协议的性能及安全性提供了一种重要手段。 相似文献
98.
99.
This paper is concerned with the stability and output tracking problems of networked control systems (NCSs) with partly quantized information. Both the remote and local systems are considered. The state variables transported from the remote system experiences time delays and quantization errors, while the local state variables do not. The purpose is to design a state feedback controller which guarantees that the output of the local system tracks the output of the remote system in the H∞ sense. This consideration is widely appeared in remote assistant systems. Based on the Lyapunov–Krasovskii (L‐K) functional approach, sufficient conditions on the existence of a quantized robust H∞ output tracking controller for NCSs are presented in terms of bilinear matrix inequalities (BMIs). Furthermore, a cone complementarity algorithm is used to convert these BMIs into a convex optimization problem. Finally, a simulation example is given to demonstrate the efficiency of the proposed method. 相似文献
100.
该文采用STC89C52单片机为核心控制单元,通过控制2个L298N电机驱动模块控制四个电机的正反转,实现智能车的差速控制;利用4个红外光电传感器以阶梯状均匀分布模式布置在智能车前部,用于采集路面的信息以实现循迹功能。该文详细论述了智能车控制系统的具体设计方案,以及智能车控制系统的软硬件实现过程,并且具体分析了智能车的车身结构对其速度和转向的影响。实验证明,该系统能很好地满足智能车对路径的识别和抗干扰能力较强的要求,智能车速度调节响应时间快,稳态误差小,具有较好的动态性能和良好的鲁棒性[1-4]。 相似文献