铌酸钠钾基无铅压电陶瓷制备技术新进展

碱金属铌酸盐系无铅压电陶瓷以其优越的压电性能和较高居里温度倍受关注.结合目前有关KNbO3-NaNbO3(KNN)基无铅压电陶瓷的报道,综述了近年来铌酸钠钾基无铅压电陶瓷在粉体制备、陶瓷的成型、烧结以及晶粒取向等制备技术研究的新进展,并从不同方面展望了今后铌酸钠钾基无铅压电陶瓷性能研究及其制备技术上可能的进展.     

绿色无铅电子焊料的研究与应用进展

概述了关于无铅电子焊料全球范围的立法与研发计划、国内外无铅焊料的发展现状及所取得的研究成果,探讨了无铅焊料合金的专利问题,进行了无铅软钎焊技术可行性、经济性和可靠性分析,介绍了无铅焊料的应用情况,并展望了前景.     

A STUDY OF FATIGUE AND CREEP BEHAVIOUR OF FOUR HIGH TEMPERATURE SOLDERS

Creep and cyclic deformation behavior of two lead-free high temperature solder alloys, 95Sn-5Ag and 99Sn-1.0Cu, a high lead alloy 97.SPb-1.SAg-1.0Sn, and an Ag-modified eutectic alloy 62.SSn-36.1Pb-1.4Ag, were studied. Room temperature and high (100°C and 150°C) temperature fatigue tests (with cyclic strain amplitude up to 6.0%) for the four solders were conducted, with the fatigue lives ranging from a few cycles to more than 100,000 cycles. It is shown that among the alloys studied, 62.SSn-36.1Pb-1.4Ag (the modified Sn-Pb eutectic alloy) has the lowest fatigue resistance in term of low cycle fatigue life (strain controlled). The high lead alloy, 97.SPb-1.5Ag-1.0Sn, has the highest strain fatigue resistance in the large strain region (Δ > 2.0%). Temperature has a significant effect on alloys 95Sn-5Ag and 99Sn-1.0Cu, but has a negligible effect on the Ag modified Sn-Pb eutectic alloy 62.5Sn-36.1Pb-1.4Ag and 97.5Pb-1.5Ag-1.0Sn. Creep studies show that these alloys generally have a very significant primary creep regime (up to 20%); thus, any realistic constitutive relation has to take such a primary creep phase into consideration. Cyclic deformation of alloy 95Sn-SAg was simulated by using a constitutive relation built upon a 2-cell model, which covers both primary and secondary creep. This model provides a good estimate of the peak stresses (the minimum stress and the maximum stress in each cycle); it agrees with experimental results when the applied cyclic strain is small and/or the applied strain rate is very low.     

(Na1/2Bi1/2)TiO3(NBT)无铅压电陶瓷的研究进展

对(Na1/2Bi1/2)TiO3基无铅压电陶瓷的研究现状进行了综述.着重概括了通过元素替代/掺杂手段对NBT陶瓷性能的影响规律.该系统陶瓷具有的强铁电性质与Bi3 密切相关;材料压电性能可通过改性技术进行调节:如通过加入第二组元化合物降低其矫顽场而提高NBT基陶瓷压电性能.总结了(Na1/2Bi1/2)TiO3基无铅压电陶瓷组成的研究思路和方向.     

Microstructure,mechanical properties and machinability of Cu–Zn–Mg and Cu–Zn–Sb brass alloys

Lead-free alloys have attracted great attentions recently due to the toxic nature of lead for the human body. In this study, low amounts of Mg and Sb were added to the Cu65–Zn35 brass and microstructure, mechanical properties and machinability of samples were compared to Cu65–Zn35 brass. Both Mg and Sb led to the promotion of β′ phase as well as the formation of new ternary copper rich intermetallic particles. It was found that these particles had a significant role in the reduction of the ultimate tensile strength, toughness, work hardening and elongation while increasing the hardness of samples. Results of machinability evaluation of samples showed that the cutting forces were decreased significantly and morphology of chips were improved compared to Cu65–Zn35 brass sample.     

新型苯并(噁)嗪树脂基覆铜板基板的研制

以4,4′-二胺基二苯甲烷、甲醛及双酚F为原料,苯酚为封端剂合成苯并噁嗪树脂,用其浸渍KH560处理的平纹玻璃布,制备了苯并噁嗪玻璃布层压板。测试结果表明,该苯并噁嗪树脂体系5%的热失重温度为410.4℃,800℃残炭为63.60%,用DMA方法测得其玻璃化转变温度(Tg)为238.5℃,制得玻璃布层压板具有优良的热稳定性和耐热性。常态下,该层压板的弯曲强度纵向为835.3MPa;横向为552.3MPa。表面电阻率体积电阻率分别为8.7×1014Ω和1.5×1013Ω.m。同时该层压板的耐锡焊性能在288℃锡浴中起泡时间大于60s,阻燃性能达到UL94-VI级。     

K+型无铅鸡蛋皮蛋加工技术

以新鲜鸡蛋为试材,采用浸泡法加工工艺,探讨KOH对加工鸡蛋皮蛋中蛋清、蛋黄的pH值、色泽及TPA(texture profile analysis)等质量特性的影响及其可能作用机理,旨在为研发K+型鸡蛋皮蛋提供依据。研究表明,5.5% KOH处理的皮蛋,在感官品质及质构特性方面较为理想。     

Effects of Na/K ratio on the phase structure and electrical properties of Na<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>K<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>NbO<Subscript>3</Subscript> lead-free piezoelectric ceramics

Lead-free piezoelectric NaxK1-xNbO3(x = 0.3-0.8)(NKN) ceramics were fabricated by normal sintering at 1060°C for 2 h.Microstructures and electrical properties of the ceramics were investigated with a special emphasis on the influence of Na content.The grain size of the produced dense ceramic was decreased by increasing Na content.A discontinuous change in the space distance was found at the composition close to Na0.7K0.3NbO3 ceramic, which indicates the presence of a transitional composition between two dif...     

Sn-Ag-Cu系无铅焊料性能研究进展

Sn-Ag-Cu是全球公认的最具潜力替代Sn-Pb钎料的无铅焊料。本文介绍了Sn-Ag-Cu系无铅焊料在熔化温度、润湿性、抗氧化性和焊接可靠性方面的主要性能以及最近的研究重点,最后对Sn-Ag-Cu系无铅焊料的发展趋势进行了展望。     

Sn-9Zn系无铅焊料钎焊接头剪切性能的研究

利用扫描电镜及万能材料实验机研究了Sn-9Zn/Cu钎焊接头的界面形貌及Sn-9Zn焊料微合金化前后钎焊接头的剪切性能变化。结果表明,Sn-9Zn/Cu界面金属间化合物为Cu5Zn8,界面层呈平整的锯齿状。由于焊接时没有保护气氛,以致Sn-9Zn氧化而使剪切性能变差,而同时添加微量RE和Ag或RE和Al元素后剪切强度大幅度增高,尤其是添加0.025%RE和0.3%Ag时剪切强度可提高46.47%,同时添加元素后剪切断口韧性断裂趋势增大。