微波电路互联用金丝键合界面空间高低温特性演化研究

金丝材料应用于航天器小型化微波模块等产品的电路封装中，金丝键合界面受高低温环境影响易产生性能变化从而影响服役可靠性。本文对金丝界面高低温特性的演化规律进行了研究，包括空间温度环境模拟试验后的界面与成分迁移、界面层厚度变化、键合金丝拉伸剪切力与失效模式演变，得出不同温度条件处理后的金铝键合界面微观组织变化规律。结果表明高低温循环试验后金丝界面仍保持较高的结合强度，一定程度的金属间化合物生长提高了键合界面强度。高温贮存试验中，随着贮存时间的增加，金丝界面层IMC（Intermetallic Compound）厚度和金属间化合物不断增长，失效破坏位置越来越多地出现在键合界面处，铝金属化层附近的金含量因扩散而增高，金铝键合界面处IMC界面层厚度的增加降低了界面结合强度。     

炔丙醚酰亚胺改性双马来酰亚胺树脂的制备与性能

合成了2，2-双［N-（4-炔丙氧基苯基）-3，4-二酰亚胺苯基］六氟丙烷（6FDPE），与（4，4''-二苯基甲烷）双马来酰亚胺（BDM）和二烯丙基双酚A（DABPA）的改性双马来酰亚胺（BDM/DABPA）树脂共混，制备了BDM/DABPA/6FDPE共混树脂。对共混树脂的黏温特性、固化反应和固化树脂的热稳定性和力学性能等进行了研究。结果表明，6FDPE能够扩展BDM/DABPA树脂的加工窗口至70 ℃以上。随着6FDPE的添加量增加，共混改性树脂在氮气氛围下共混树脂固化物的5%热失重温度（）升高达到416 ℃，800 ℃的残留率（Y_r800℃）高达41%，但玻璃化转变温度（T_g）会降低，仍高于300 ℃。6FDPE可增韧BDM/DABPA树脂，共混改性树脂的冲击强度提高至23.9 kJ/m²，增加了55%，但树脂浇铸体的弯曲强度和拉伸强度分别降低至132 MPa和78 MPa，都下降了13%。     

改性环氧树脂的低温力学性能研究进展

近年来,随着国防、航天、大型低温工程(EAST和ITER等)和应用超导等高科技领域的迅猛发展,环氧树脂在低温下的应用愈来愈广泛.本文主要从改性环氧树脂的拉伸强度和冲击韧性两方面,对其低温下的力学性能研究进展进行论述.研究显示,柔性改性和纳米填料改性都可以提高其低温力学性能(拉伸强度和冲击韧性),相关研究工作为改性环氧树脂在低温环境下的应用提供了依据.     

Improving tensile-shear properties of friction stir lap welded dissimilar Al/Mg joints by eliminating hook defect and controlling interfacial reaction

To improve tensile-shear properties of fiction stir lap welded(FSLW) dissimilar Al/Mg joints, pin-tip profiles were innovatively designed and welding speed was optimized, and effects of them on formation, interface microstructure and mechanical properties of different FSLW joints were investigated. With increasing the welding speed, the tensile-shear load of FSLW joints produced by three pins presents an increasing firstly and then decreasing trend. Compared with Rpin, the hook and hole defect i...     

Microstructural formation and mechanical performance of friction stir double-riveting welded Al-Cu joints

A novel friction stir double-riveting welding (FSDRW) technology was proposed in order to realize the high-quality joining of upper aluminum (Al) and lower copper (Cu) plates, and this technology employed a Cu column as a rivet and a specially designed welding tool with a large concave-angle shoulder. The formations, interfacial characteristics, mechanical properties and fracture features of Al/Cu FSDRW joints under different rotational velocities and dwell times were investigated. The results showed that the well-formed FSDRW joint was successfully obtained. The cylindrical Cu column was transformed into a double riveting heads structure with a Cu anchor at the top and an Al anchor at the bottom, thereby providing an excellent mechanical interlocking. The defect-free Cu/Cu interface was formed at the lap interface due to the sufficient metallurgical bonding between the Cu column and the Cu plate, thereby effectively inhibiting the propagation of crack from the intermetallic compound layer at the lap interface between the Al and Cu plates. The tensile shear load of joint was increased first and then decreased when the rotational velocity and dwell time of welding tool increased, and the maximum value was 5.52 kN. The FSDRW joint presented a mixed mode of ductile and brittle fractures.     

Si粉特性对反应烧结Si3N4多孔陶瓷的强韧性及介电性能的调控作用

Si₃N₄多孔陶瓷具有优异的力学性能、介电性能、热学性能和化学稳定性等，特别适用于高温、大载荷、强侵蚀环境下的宽频透波材料。反应烧结Si₃N₄多孔陶瓷在性能、工艺和成本方面优势显著，原料Si粉特性显著控制着其物相、显微结构、力学和介电性能。本文以不同粒径和纯度的Si粉为原料制备注凝成形、反应烧结Si₃N₄多孔陶瓷。结果表明，双粒径配料使素坯产生紧密堆积效应，其遗传并进一步演化出两级显微组织强韧化机制，双粒径配料5 & 45 μm时的弯曲强度和断裂功获得最大值109.94 MPa和990.74 J/m²。该值分别比单粒径配料5和45 μm时的值提高了111.42%、25.97%和46.55%、20.46%；介电常数和介电损耗分别约为4.20和0.007。注凝成形、反应烧结Si₃N₄多孔陶瓷可以兼顾力学性能和介电性能，适用于透波罩等异形、大尺寸构件。     

Recent advances and trends in roll bonding process and bonding model: A review

This review presents a thorough survey of the roll bonding process with a focus on the bimetallic bars/tubes as well as the bonding models and criteria. The review aims to provide insight into cold, hot and cryogenic bonding mechanisms at the micro and atomic scale and act as a guide for researchers working on roll bonding, other joining processes and bonding simulation. Meanwhile, the shortcomings of roll bonding processes are presented from the aspect of formable shapes, while bonding models are shown from the aspect of calculation time, convergence, interface behavior of dissimilar materials as well as hot bonding status prediction. Two well-accepted numerical methodologies of bonding models, namely the contact algorithm and cohesive zone model (CZM) of bonding models and in simulations of the bonding process are highlighted. Particularly, recent advances and trends in the application of the combination of mechanical interlocking and metallurgical bonding, special energy fields, gradient structure, novel materials, green technology and soft computing method in the roll bonding process are also discussed. The challenges for advancing and prospects of the roll bonding process and bonding model are presented in an attempt to shed some light on the future research direction.     

国产M55J级碳纤维与两种典型树脂界面性能研究

为了夯实国产M55J级碳纤维在航天构件中的应用基础，重点研究了国产M55J级碳纤维与航天环氧和氰酸酯树脂的界面性能，并与进口M55J碳纤维进行对比。采用扫描电子显微镜、原子力显微镜对碳纤维的微观形貌进行表征，通过接触角测量、红外光谱分析和微脱粘测试对碳纤维与航天树脂的粘附功、浸润性、化学反应特性和界面剪切强度进行测定。结果显示，国产M55J级碳纤维表面存在大量沟槽，上浆剂形成少量突起；国产M55J级碳纤维与两种树脂的浸润性优于M55J碳纤维与树脂浸润性，国产M55J级碳纤维与两种航天树脂的粘附功分别为55.76和48.61 mN/m，均高于进口碳纤维的粘附功；国产M55J级碳纤维上浆剂与两种航天树脂经高温固化后反应程度达到100%；国产M55J级碳纤维与两种航天树脂的界面剪切强度分别为74.62和62.99 MPa，均高于M55J碳纤维。     

宇航用键合金丝评价体系及其应用研究

键合金丝广泛应用于小型化星载装备多芯片组件中，而复杂的空间环境要求键合金丝具有良好的可键合性和应用可靠性。本文在深入分析星载多芯片组件应用需求和典型失效模式的基础上，构建了键合金丝应用评价体系，从材料基础性能、工艺适用性和应用可靠性三个方面对键合金丝的可用性进行了全面的评估。应用本文提出的评价体系，对某国产键合金丝进行了系统应用评价，各项测试表明国产键合金丝与拟替代的进口金丝基础性能指标、可键合性和键合可靠性均相当，且在高温下国产金丝键合强度退化慢于进口金丝，呈现了更优异的应用可靠性。     

碳纤维复合材料轴向压缩性能测试方法对比北大核心CSCD

轴向压缩性能一直是复合材料力学性能评价表征研究的难点。本文以国产T800级、M40J级碳纤维复合材料为研究对象,从试验研究、机理分析、计算模拟等角度,系统对比并分析了四种常用复合材料压缩性能测试方法的优劣与适用性,提出了优化的测试条件。试验与模拟结果表明,剪切加载方法(GB/T 3856—2005)易产生应力集中造成试样提前破坏,使压缩强度测试结果相比美标剪切加载方法(ASTM D3410—2016)降低约9%;端部加载(SACMA SRM 1R—94)测试结果较美标剪切加载和联合加载方法(ASTM D6641—2014)高3%~6%。测试条件优化研究中发现,加强片材质对破坏模式影响较大,强界面高强度复合材料适宜采用金属加强片,弱界面低强度复合材料适宜采用玻璃钢加强片。分析试样断口形貌,剪切加载和端部加载方法都可以观察到单向复合材料以纤维“跪折”为主的破坏模式。从测试结果和破坏模式来看,端部加载方法是较优的压缩强度测试方法。