微量元素添加对多元Sn-Bi系焊料合金组织与性能的影响

传统焊料合金由于熔点温度高,不能满足部分有机基板、温度敏感器件以及3D封装等多层封装形式的低温封装要求.以Sn-Bi合金为基体,通过添加微量Ag、Cu、Co和Ni元素形成新型多元合金,对多元合金的熔化性能、润湿性能、微观组织和力学性能进行研究.结果 表明:微量元素的添加(质量分数0～1％)对多元Sn-Bi系合金的固相线...     

42CrMo钢激光淬火组织和硬度的研究

采用YLS-3000型光纤激光器对42CrMo钢进行表面熔凝淬火处理,通过金相显微镜、扫描电镜及维氏硬度计的观察与检测,分析淬硬层组织、硬度、深度及其与激光工艺参数之间的相互关系。结果表明,淬硬层深度随激光功率的增大和扫描速度的降低而增大,随激光功率的减小和扫描速度的增加而减小,而硬度的变化不大。激光熔凝淬火后表层出现深约0.3 mm的熔化区,其硬度比内侧稍低,淬硬层深度可达2 mm以上,硬度约为660HV,但熔化区域中心会出现不均匀的变形,进行熔凝淬火时需预留0.2 mm的加工余量。     

多孔硅表面冷电子发射的研究

本文研究了多孔硅二极管表面发射电子的特性。ＰＳ二极管由薄金膜、ＰＳ层、ｎ型Ｓｉ衬底和欧姆接触铝背电极组成。在真空中,当在金属电极和铝背电极间加适当高的正电压且在收集极板和金电极间存在高外电场时,伴随着可见光,电子均匀地穿过金膜出来。电子发射的机理基于ＰＳ层外表面附近的强场效应。     

多层间隔式结构多孔硅冷阴极电子发射的研究

在多孔硅（ＰＳ）表面电子发射冷阴极中采用间隔式多层结构。由此,器件电子发射效率显著提高,在３２．５Ｖ偏压下,发射效率达１３．５％,发射电流密度２９μＡ／ｃｍ＾２;工作电流和发射电流的波动性明显减小;器件稳定性得到提高。     

Li2O-ZnO-SiO2系结晶型低熔点封接玻璃的研究

研制了一种用于与软质玻璃和金属合金封接、以Li2O-ZnO-SiO2为基础的三元系结晶性低熔点玻璃焊料.通过不同的热处理制度以及DSC,纽扣试验等分析手段,对该体系焊料玻璃进行了研究.结果表明,玻璃焊料在600～640℃的流散性良好,能与金属合金、平板玻璃封接.同时探讨了封接温度、封接时间、金属合金预处理的程度以及保护气氛等工艺参数对封接质量的影响.     

“互联网+”背景下我国冷链物流与互联网产业融合及实施路径研究

针对人们对冷链物流需求不断增强现状,为解决冷链物流存在的各项问题,要做好冷链物流与互联网产业融及实施路径研究,希望文中内容对于提高冷链物流市场化能够有所帮助。     

Use of Palm Mid-Fraction in White Chocolate Formulation

Samples of two types of palm mid-fraction (PMF I, a commercial sample and PMF II, from a laboratory-scale acetone fractionation of PMF I) and a Malaysian deodorised cocoa butter sample were used as the main components in the fat phase for white chocolate formulation. The monounsaturatedtriacylglycerol contents of these fats were 853, 899 and 903 g kg⁻¹, respectively.All the fats had free fatty acid contents of less than 10 g kg⁻¹ and melting points in the range of 34·0–34·5°C. The solid fat content profiles for the three fats were very steep. Differential scanning calorimeter analyses showed that all the fats had two melting peaks, T1 and T2. Results of the study showed that the tempering time to produce a well-tempered chocolate using PMF I was longer than that using PMF II, whereas, the time to produce a well-tempered cocoa butter chocolate increased with increase in the tempering temperature. Chocolates made with PMF I and II were well tempered between 17 and 19°C and with cocoa butter at 23°C. Thermal analyses, carried out on the chocolate showed that PMF I and II produced three melting peaks, T1, T2′ and T2 whereas most of the cocoa butter chocolates exhibited only one melting peak, T2. Storage studies showed that most of the chocolates had good bloom resistance for up to 12 weeks storage.     

Multi-Functional Black Bioactive Glasses Prepared via Containerless Melting Process for Tumor Therapy and Tissue Regeneration

Tissue regeneration in complex lesions such as the site of tumors, bacterial infection, and sites lacking blood vessels, has been a huge challenge. Therefore, developing bioactive implantable materials with multi-functional properties such as tumor destruction, bacteria growth inhibition, and angiogenesis promotion is of great significance. In this study, black CaO-SiO₂-TiO₂ (CST) glasses are prepared through the containerless melting approach, by which heterogeneous nucleation can be avoided and thereby glass formation becomes possible via fast quenching. This approach enables the formation of trivalent titanium (Ti³⁺) without using a reducing atmosphere or reducing agents. The black CST glasses are found in this study to possess a strong ability to inhibit bacteria and tumors by their excellent photothermal and photocatalytic effects. Strikingly, these glasses also promote the formation of blood vessels and accelerate the healing of chronic wounds by the synergistic effects of the photothermal effect and Si ions. Thus, this glass system can be a promising multi-functional material for tissue regeneration in complex lesions.     

铜锡合金纳米粒子的制备和性能研究

通过化学还原方法制备了铜锡合金纳米粒子,并研究分析了其的尺寸和热学性能。铜锡纳米粒子的X射线衍射分析结果显示,合成产物主要是锡纳米颗粒和铜锡合金(Cu6Sn5)纳米颗粒组成,且这些纳米粒子并未被氧化。其示差扫描量热法测得结果表明,本次合成的纳米颗粒的熔点为202.98 ℃,适合现代电子封装技术对低熔点封装材料的要求。     

(Sn-9Zn)-xBi钎料组织性能研究

运用莱卡显微镜、X射线衍射仪及电化学测试系统等仪器设备,对(Sn-9Zn)-xBi(x=0,1,3和5)钎料组织性能进行研究.结果表明:当x小于5时,Bi可明显影响(Sn-9Zn)-xBi钎料中富Zn相尺寸及分布,钎料的熔化温度随Bi含量的增加而降低至188℃;钎料的润湿性随Bi含量增加而得到改善,其中以x在1～3为最...