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摘 要随着航空航天科技等科学领域的飞速发展，钼与石墨的焊接结构件的运用也随之增加。本文介绍了钼与石墨的化学物理特性以及钼与石墨钎焊的研究现状。由于石墨的润湿性比较差，大多数钎料难以有效地润湿石墨，因此本课题采用含有活性元素 Ti的钎料 Ag-Cu-Ti对钼与石墨进行了真空钎焊。运用扫描电子显微镜(SEM)和其能谱分析（EDS）等方法，对钎焊接头的微观组织进行观察分析，研究了不同钎焊工艺下（主要为钎焊温度和保温时间），接头中元素的扩散和分布特点。实验研究结果表明：在钎焊温度达到 830℃以上并且保温 3分钟以上时，钎料即熔化，Ag-Cu发生共晶反应。随着钎焊温度和保温时间的增加，Ag72-Cu28-Ti3钎料能够发生更充分地扩散，并且石墨和钼基体中C、Mo元素也开始发生不同程度的溶解。钎料中的Ti元素在一定工艺参数条件下，会与石墨中的 C元素发生反应生成TiC层，有效提高了对石墨的润湿性，改善界面张力；在一定工艺参数条件下，钎料中的 Ti元素会与钼基体中的 Mo元素形成无限固溶体，为真空钎焊提供了有利条件。实验结果得到了在现有实验设备和数据情况下，采用 Ag72-Cu28-Ti3活性钎料对高强石墨和纯钼钎焊最佳的工艺参数条件为870℃，保温 15min。58966
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毕业论文关键词：石墨；钼；真空钎焊；Ag-Cu-Ti活性钎料；钎焊温度；保温时间
Abstract With the rapid development of aerospace science and technology and other fields ofscience, the use of welded structure of molybdenum and graphite increases. This articledescribes the chemical and physical properties of molybdenum and graphite as well asgraphite and molybdenum research status brazing.Because graphite is relatively poor wetting, solder most difficult to effectively wetgraphite, so this issue with an active solder Ag-Cu-Ti molybdenum and graphite vacuumbrazing. A scanning electron microscope (SEM) and its spectroscopy (EDS) and othermethods, the microstructure of brazed joints were observed and analyzed, studied underdifferent soldering processes (mainly for soldering temperature and time), the jointelements diffusion and distribution.Experimental results show that: when the brazing temperature reaches 830 ℃ or moreand holding more than 3 minutes, Ag-Cu-Ti brazing material that is liquefied, Ag-Cueutectic reaction. With the increase of brazing temperature and holding time, Ag-Cu-Tibrazing material can occur more fully diffused and graphite and molybdenum substrate C,Mo elements have begun to varying degrees of diffusion. Brazing alloy Ti elements undercertain process parameters, will work with graphite element C reacts generate TiC layer,effectively improve the wettability, interfacial tension to improve graphite; under certainprocess parameters, brazing alloy the Ti elements are molybdenum substrate in an infinitesolid solution Mo element, provided the conditions for the vacuum brazing. The resultsobtained in the case of existing laboratory equipment and data, using Ag72-Cu28-Ti3active brazing of high-strength graphite and pure molybdenum brazing optimum processparameters.
Keywords：graphite; molybdenum; vacuum brazing; Ag-Cu-Ti active brazing;brazing temperature; holding time
目 录
第一章 绪论.. 1
1.1引言.1
1.2钎焊技术的特点.2
1.2.1 钎焊技术的优缺点..2
1.2.2 钎焊工艺 2
1.2.3 真空炉中钎焊的优缺点..3
1.2.4 钎焊过程 4
1.2.5 钎料5
1.3钼及其合金的钎焊研究现状.7
1.4石墨材料的钎焊性9
1.5本课题主要的研究内容. 10
第二章 实验方法及设备.12
2.1实验材料.. 12
2.2实验设备.. 13
2.3实验过程.. 14
2.4钎焊工艺参数的选择.. 14
2.4.1 钎焊温度. 14
2.4.2 保温时间 15