Anti-tarnish property of sterling silver alloy with yttrium addition

It has been demonstrated that sterling silver alloy is a widely used material in the jewelry industry.The anti-tarnish property is one of the most important properties of this material.In this work,the effect of yttrium on the corrosion resistance,and tarnish resistance properties ofsterling silver alloy were investigated with the use of CIE-LAB uniform color scale,which gained acceptance as an effeetive way to assess color.To better understand the mechanism of the effect,the distribution of yttrium in the alloy was analyzed by mainly segregating in gaps among dendrite crystals and grain boundary.An increase in yttrium content in sterling silver alloy resulted in a decrease in the amount of eutectic structure.The tarnish and corrosion resistance of sterling silver were improved with yttrium content increase.However,too high yttrium conteut will lead to poor anti-tarnish properties.     

饰品用银合金添加元素研究进展

总结了饰品用银合金研究中的关键问题,阐述了银合金强化、抗自然时效软化和抗变色能力的主要进展。从固溶强化、细晶强化、时效强化和第二相强化等方面讨论了银合金添加元素的强化机理,以及添加元素对抗自然时效和抗变色能力的影响。     

超疏水涂层对沥青路面防冰性能的影响

采用有机硅橡胶与表面改性过的微米/纳米粉末制备了超疏水涂层,研究了该涂层对于沥青路面防冰性能的影响.接触角测试结果表明,该超疏水涂层的接触角达到了160°;沥青混合料表面结冰温度试验结果表明,在同样降温条件下,相比于无涂层的沥青混合料试件,涂有超疏水涂层沥青混合料试件的表面水滴结冰时间延长了1.5倍;沥青混合料表面冰层黏结力试验结果表明,相比于无涂层的沥青混合料试件,涂有超疏水涂层沥青混合料试件的表面冰层黏结力在-5℃时减小了84%.     

饰品用银合金的研究进展

介绍了饰品用银合金的概况,重点综述了抗变色饰品银合金以及抗时效软化饰品银合金的最新研究进展,并对饰品银合金的发展进行了展望.     

摩托车用霍尔效应转速传感器的设计

对摩托车用霍尔效应转速传感器进行了开发设计.介绍了传感器的设计方案,使用FEMM二维有限元软件对方案进行模拟仿真,得到了各种参数对结果的影响规律.     

基于动刚度法的热环境下纤维增强聚合物基复合薄板抗振性能的退化

从动力学角度,提出了动刚度法来研究热环境下纤维增强聚合物基复合薄板的抗振性能退化特性。首先,考虑脉冲激励载荷的影响,利用能量法、板壳理论和振型叠加法等,实现了热环境下动刚度的理论求解。同时,总结和归纳了热环境下复合薄板抗振性能退化的分析流程,并以TC500碳纤维/树脂基复合薄板为例,通过对比理论与测试获得的动刚度、固有频率、阻尼和振型结果,证明了该动态指标的有效性和方法的可行性,可以利用该指标来量化评价复合薄板在热环境下的动态性能退化问题。      

Effect of sodium ions in synthesis of titanium silicalite-1 on its catalytic performance for cyclohexanone ammoximation

Titanium silicalite-1 (TS-1) has been hydrothermally synthesized with tetrapropylammonium hydroxide (TPAOH) as the template in the presence of various amounts of Na⁺, characterized by inductively coupled plasma, X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and ultro-violet-visible spectroscopy and studied in cyclohexanone ammoximation. The characterization results show that with the increase of Na⁺ concentration in the synthesis, both the crystal sizes of TS-1and extra framework Ti increase but framework Ti decreases. The addition of Na⁺ below 3 mol-% of TPAOH in the synthesis does not influence the catalytic properties with above 98% conversion of cyclohexanone and 99.5% selectivity to cyclohexanone oxime. However, at the concentrations of Na⁺≥3 mol-% of TPAOH in the synthesis, the catalysts are deactivated faster with the increase of Na⁺ addition, which can be attributed to more high molecular weight byproducts deposited in the large TS-1 particles and the loss of the frame-work titanium. The results of this work are of great importance for the industry.     

水布垭面板坝实测沉降分析与土石坝沉降统计预报模型

本文对水布垭面板坝实测沉降进行整理分析,大坝变形监测仪器工作正常,坝体实测沉降分布规律合理,最大沉降为已填筑坝高的1%,推算填筑堆石体垂直压缩模量达100MPa,坝体填筑质量良好.本文考虑土石料变形的影响因素及材料流变特性,应用统计回归方法建立耦合的指数型坝体沉降统计预报模型,与实测数据拟合很好,预测大坝竣工5年后的沉降略有增加.     

简述欧盟法规(EU)No 168/2013中摩托车OBD要求

简述欧美等主要国家地区标准法规对摩托车车载诊断系统(OBD)要求现状,并重点介绍了最新颁布的欧盟法规(EU)No 168/2013中对摩托车OBD的要求。该法规对我国摩托车行业研发OBD系统有着重要的指导意义。     

市场经济条件下乡镇畜牧兽医站经营管理新探

随着农业产业化的调整,畜牧业的产业格局也发生了巨大的变化,家畜的养殖由使役型逐渐发展为食用型,由少品种向多品种的格局发展,乡镇兽医站的业务水平、管理水平直接影响着畜牧业的生产与发展。