(Cu-50TiH_2)+SiC_p复合粉体焊料连接石墨/铜接头的微观结构

碳材料与铜的连接在汽车及能源等领域具有潜在的应用。采用Cu、TiH2和SiC粉末组成的复合粉体焊料在950℃/10min工艺条件下真空钎焊石墨与铜,并研究复合粉体焊料中SiC含量对石墨/铜接头剪切强度的影响。结果表明,复合焊料中添加SiC有利于接头室温剪切强度的提高。当SiC体积分数为10%时,接头室温剪切强度最高,为19.2MPa。微观分析表明,连接过程中,复合粉体焊料中TiH2分解产生的Ti与SiC发生原位反应,生成TiC、Ti5Si3及Ti3SiC2等反应产物;另外,Ti与石墨母材发生界面反应形成厚度为2~3μm的TiC反应层,Ti和Cu则形成Ti3Cu4等金属间化合物。由于Ti3SiC2在高温下具有塑性,可在一定程度上缓解石墨/铜接头的残余热应力。同时,晶须状和颗粒状的反应产物弥散分布在连接层中,对接头起强化作用,也有利于石墨/铜接头性能的提高。     

Tarnish Testing of Copper-Based Alloys Coated with SiO_2-Like Films by PECVD

The tarnishing test in the presence of hydrogen sulfide（H2S） vapors has been used to investigate the tarnish resistance capability of copper-based alloys coated with Si02-like films by means of plasma-enhanced chemical vapor deposition（PECVD） fed with a tetraethoxysilane/oxygen mixture.The chemical and morphological properties of the films have been characterized by using infrared absorption spectroscopy（IR） and scanning electron microscopy（SEM）with energy disperse spectroscopy（EDS）.The corrosion products of the samples after the tarnishing test have been identified by X-ray diffraction analysis（XRD）.It has been found that SiO2-like films formed via PECVD with a high O2 flow rate could protect copper-based alloys from H2S vapor tarnishing.The alloys coated at the O2 flow rate of 20 sccm remain uncorroded after 54days of H2S vapor tarnish testing.The corrosion products for the alloys deposited at a low O2flow rate after 54 days of tarnish testing are mainly composed of brochantite.