Silicon doped carbon/Cu joints based on amorphous alloy brazing for first wall application

Amorphous ribbon-type filler-metals represent a promising selection for joining heterogeneous materials together. In this work, rapidly solidified ribbon-type Ti based amorphous filler with a melting temperature of 850 °C and a thickness up to 20 μm is used to join silicon doped carbon to pure copper. SEM examinations demonstrate that a high quality brazed joints could be acquired. The brazed seam has a uniform structure and pore free along its entire length. TiC and ZrC are formed near the interface of carbon and filler-metal when the brazing holds enough time. Using very thin Mo and Cu foil (0.2 mm in thickness) as multiple interlayer are very effective to mitigate the thermal stress occurred in the interface between carbon and copper. The shear strength of this carbon-multiple interlayer-copper joint is more than 20 MPa, and the rupture is mainly occurred on the carbon side.     

Preparation of ultra fine nickel-copper bimetallic powder for BME-MLCC

The preparation of ultra fine nickel-copper bimetallic powder with two-stage chemical reduction method was investigated. Reductive sugar and hydrazine hydrate were employed as reducing agent in different reductive stage, respectively. Reaction of CuSO₄·5H₂O with reductive sugar at 70 °C gives cuprous oxide and copper particles, then as-prepared mixture and nickelous hydroxide were reduced by hydrazine hydrate, and nickel-copper powder having excellent dispersibility was prepared. Influences of nickel added on composition and dispersibility of powder were studied. TG/DTG/DTA of nickel-copper powder, which is stable in room temperature, were discussed with thermal analyzer. Relation of nickel content to oxidation temperature was investigated. Ni-Cu bimetallic powder particles have a fully coated structure when nickel content is up to 30%. As-prepared nickel-copper powder was applied in base metal electrode-multilayer ceramic capacitor (BME-MLCC). The end termination has high adhesion force, fairly good densification, low resistivity, excellent solderibility behavior and resistance behavior to soldering.     

溶胶-凝胶法制备(Sr,Pb)TiO3纳米晶粉及表征

采用溶胶－凝胶法成功地合成了（Sr,Pb)TiO3纳米晶粉，并利用FTIR技术对凝胶的形成过程及350℃，1．5h煅烧获得的粉体材料进行了表征。实验以TG－DSC分析作为拟定煅烧温度的依据，以XRD作为煅烧产物的分析手段，最佳煅烧温度为600℃，所合成的（Sr,Pb)TiO3纳米晶粉的平均晶粒尺寸约为21nm，属钙钛矿型立方顺电相结构。     

稀土钕对激光快速成形TC4合金组织及性能的影响

针对氢化脱氢钛合金粉末氧含量较高的问题，研究了添加稀土钕对激光快速成形TC4合金组织及性能的影响。结果发现，添加稀土Nd后，激光快速成形TC4合金的宏观晶粒尺寸变化不大；但随稀土添加量的增加，初始β列状晶逐渐转化为全β等轴晶，晶粒内部的魏氏α组织逐渐转变为网篮α，粗化α条不断增多，呈现团束聚集趋势，晶界α集束体积分数也不断增大；随稀土添加量的增加，激光快速成形TC4合金的室温塑性先大幅度提高，然后急剧降低；稀土添加量为0．1％～0．2％（质量分数，下同）时，氧含量为0．26％的氢化脱氢TC4合金粉末激光快速成形件沉积态的抗拉强度达975MPa，延伸率9．5％，满足锻件标准要求。     

快速凝固铝硅合金粉末加热过程中硅颗粒的粗化行为

利用差示扫描量热仪(DSC)、电子显微镜等设备对Al-12.8%Si合金粉末的原始状态及热处理后的状态进行了分析。发现其显微组织有两个连续的变化过程:在156℃时,固溶在基体Al中的过饱和Si开始析出,并在340℃发生粗化,随着加热温度的升高,粗化现象仍然存在。另外,对Si颗粒的粗化机理进行了研究,发现其粗化符合经典的LSW理论。     

各向异性Sm2Fe17Nx磁粉的结构与磁性能

研究了Sm2Fe12Nx磁粉的制备、结构与磁性能，发现Sm—Fe合金的铸态组织主要由Sm2Fe17、α—Fe和SmFe2三种物相组成，而经过1000℃均匀化退火48h处理后富Sm的SmFe2相基本消失，α—Fe相的品粒变小，数量减少。随着氯化时间延长到10h，Sm2Fe17相始终未改变其Th2Zn17型结构，而氯原子浓度增加，所有的X射线衍射峰均向小角度方向移动；但在氮化时间超过10h后，物相要发生变化，导致磁性能降低。在500℃下流动的氮气氛中对Sm2Fe17合金氮化2、4、6、10h未加磁场取向的磁粉中，以氮化6h的磁性能值最高：σr＝35．44Am^2/kg(emu／g)，Hc＝58kA／m(729．03Oe)。磁性能值偏低的原因与测量磁场较低，粒径分布不均匀及粒径较大有关。     

PP／mPE／无机填料三元复合材料的形态结构和力学性能

采用刚性无机填料对茂金属聚乙烯（mPE)弹性体增韧聚丙烯（PP）二元共混体系进行增强，从而制得PP／mPE无机填料三元复合材料。分别探讨了CaCO3用量对复合材料拉伸性能和低温冲击性能影响，并考察了不同填料的增强效果。实验结果表明，由于弹性体的存在，无机填料的增强作用减弱；共混物的低温冲击强度也因填料的加入而大幅度下降，但经过表面处理的高岭土体系的冲击强度反而提高。SEM断裂形貌显示，未经表面处理的填料和基体的界面结合较弱，而改性高岭土则以层状结构分散于基体中，并呈现牢固的界面结合。     

低翘曲玻纤增强PET复合材料的制备和性能研究

依据降低翘曲的机理，选用不同降低翘曲的方法，制备了系列翘曲玻纤增强PET复合材料，结果表明，具有较高形状对称性的填料，如滑石粉，云母粉和玻璃微珠都能不同程度地降低玻纤增强PET体系的翘曲，非晶聚合物也能有效改进该体系的翘曲性能。     

补强剂和共混工艺对PA/PVC/NBR三元共混弹性体性能的影响

在选择三元共聚尼龙（PA）、聚氯乙烯（PVC）、丁腈橡胶（NBR）为主体材料，制备PA／PVC／NBR（10／30／60）三元共混弹性体的工作基础上，进一步探讨了填料品种和用量，共混温度，加料顺序等因素PA／PVC／NBR三元共混弹性体的影响。试验结果表明：在PA／PVC／NBR（10／30／60）共混体系中，补强型填料的补强效果优于非补强型的填料，6种填料补强效果依次是：快压出炭黑＞半补强炭黑＞白炭黑＞活性重质，CaCO3＞陶土＞滑石粉，快压出炭黑的适宜用量是20－50份。在制备PA／PVC／NBR三元共混物时，适宜的共混温度是122－140℃，并且采用二段法混工艺制得的共混物性能优于采用一段法共混工艺。     

电磁屏蔽涂料的发展现状及趋势

电子产品的日益普及使得电磁干扰成为一个突出问题,应用电磁屏蔽涂料是消除电磁干扰简单而有效的方法,本文介绍了电磁屏蔽涂料的组成、效能评价方法、技术思想、存在的问题以及发展趋势。复合型以及水性屏蔽涂料具有广阔的研发前景,高效能、宽频带、寿命长的电磁屏蔽涂料将会受到市场欢迎。