【作者】 李霞；

【导师】 蒋建敏； 贺定勇；

【作者基本信息】 北京工业大学 ， 材料科学与工程， 2010， 硕士

【摘要】 陶瓷材料表现出许多良好的高温性能,并能在恶劣条件下保持良好的环境稳定性。然而,大型或复杂组件的使用受到加工成本的影响,这就需要制造小的元件,并将其连接在一起。在高温和氧化环境条件下,接头性能会受到很大的影响。最近,一种被称为反应空气钎焊(RAB)的新技术,在陶瓷连接方面显示了巨大潜力。与传统的活性金属钎焊不同,它采用的是一种高温下形成液相的氧化物-金属钎料,并且钎焊过程不需要真空或惰性气氛保护。本文采用Ag、CuO、Ti粉配制Ag-CuO系和Ag-CuO-Ti系粉末钎料,分别对氧化铝陶瓷和氧化锆陶瓷进行反应空气钎焊试验。通过DSC、铺展性能试验、金相分析、扫描电子显微镜、能谱分析、X射线衍射及四点弯曲试验,分别对钎料的熔化特征、铺展性能和接头的显微硬度、微观结构、界面物相组成、接头强度等进行了测定和分析。本文研究成果如下:1)在Ag-CuO系钎料中加入少量Ti,提高了钎料的铺展性能,当Ti加入量为0.5mol%时效果较好。采用RAB钎焊技术,当钎焊温度为1100℃,保温时间为10min时,Ag-8CuO-0.5Ti钎料的铺展性能、界面硬度过渡情况和接头强度等综合性能最好。2)钎焊过程中,钎料中各组分向陶瓷基体扩散,氧化铝陶瓷基体内的Al元素和氧化锆陶瓷中的Zr元素也向钎料内扩散和溶解。在Ag-CuO系钎料中添加少量的Ti,氧化铝陶瓷接头中黑色过渡层在界面处堆积减少,钎料大量渗入氧化铝陶瓷母材。3) Ag-CuO系钎料与氧化铝陶瓷发生界面反应,反应产物为CuAlO2和CuAl2O4,与氧化锆陶瓷未发生界面反应;Ag-CuO-Ti钎料与氧化铝陶瓷和氧化锆陶瓷均发生了界面反应,反应的产物分别为CuAl2O4、TiO2和ZrTiO4,TiO2。4)在试验范围内,Ag-CuO系钎料中CuO为8mol%时氧化铝和氧化锆钎焊接头的四点弯曲强度分别达到最大值206.11MPa、454.58MPa。Ag-8CuO中加入0.5mol%提高了接头强度。在1100℃保温10min,Ag-8CuO-0.5Ti钎料与氧化铝陶瓷和氧化锆陶瓷钎焊接头的四点弯曲强度最高,分别为212.36MPa、503.44MPa,约为陶瓷母材强度的66%、84%,陶瓷钎焊接头的断裂形式均为脆性断裂。更多还原

【Abstract】 Ceramic materials exhibit many desirable high temperature performances and also provide environmental stability in harsh conditions. However, the applications of large or complex components is limited by the processing cost, and manufacturing smaller components and joining them together is a desire. The properties of joints will be greatly affected by high temperature and oxidation environment. A recently- developed technique for joining these components, referred to as reactive air brazing (RAB), has shown vast potential for these applications. Different from the traditional active metal brazing, RAB uses a liquid-phase oxide-metal melt at high temperature and the process does not require a vacuum or inert atmosphere.In this paper, the Ag-CuO system and the Ag-CuO-Ti system filler metals are prepared by Ag, CuO, Ti powder, and these filler metals are carried out with RAB on alumina and zirconia substrate respectively. The melting characteristics and spread abilities of the filler metals, microhardness, microstructure, interface phases composition and strength of the joints were measured or analyzed through different scanning calorimetry, spreading tests, optical microscopic structure inspection, SEM and energy spectrum analysis, X-ray diffraction analysis and four-point bending tests.The research results are as follows:1) Small amount of Ti adding to the Ag-CuO system filler metals improved the spreading properties of the filler metals, and the effect of adding 0.5mol%Ti is best. The comprehensive performance of spreading properties, interface microhardness transition and joint strength of Ag-8CuO-0.5Ti filler metal are best at 1100℃and holding 10min.2) In the process of brazing, the filler metal elments diffuses to the ceramic substrates. The Al element in alumina ceramic substrates and the Zr element in zirconia ceramic substrates also diffuse to the filler metals. Adding a small amount of Ti to Ag-CuO system filler metals, the black transition layer accumulation reduced in the interface of alumina ceramic, and a large number of brazes infiltrated alumina ceramic materials.3) The interfaces of Ag-CuO/Al2O3 occured interfacial reactions, the reaction products were CuAlO2 and CuAl2O4, but no interfacial reactions at the interface of the Ag-CuO/ZrO2. Both the interfaces of Ag-CuO-Ti/Al2O3 and Ag-CuO-Ti/ZrO2 occured interfacial reactions, reaction products were CuAl2O4, TiO2 and ZrTiO4, TiO2 respectively.4) In the test range, the four-point bending strength of alumina and zirconia were best at the Ag-8CuO of the Ag-CuO system filler metals, respectively reached 206.11MPa, 454.58MPa. Adding 0.5mol%Ti to Ag-8CuO increased the joint strength. The four-point bending strength of alu mina ceramic joints and zirconia ceramic joints brazed by Ag-8CuO-0.5Ti filler metal were the highest at 1100℃and holding for 10min, respectively reached 212.36MPa, 503.44MPa, about 66%, 84% of the ceramic materials strength, and the fracture mode of ceramic joints were brittle fracture.更多还原