本文關(guān)鍵詞： SiC/Ti擴(kuò)散連接 脈沖電場(chǎng) 交流電場(chǎng) 界面結(jié)構(gòu) 剪切強(qiáng)度　出處：《哈爾濱工業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：SiC陶瓷具有耐高溫、抗腐蝕、抗氧化性強(qiáng)等優(yōu)越性能,利用連接方法制備陶瓷/金屬?gòu)?fù)合結(jié)構(gòu)件,能夠?qū)⑻沾膳c金屬的優(yōu)異性能充分運(yùn)用,對(duì)拓寬陶瓷材料的應(yīng)用范圍具有特別重要的意義。本文采用擴(kuò)散連接方法制備Si C/Ti復(fù)合構(gòu)件,并針對(duì)擴(kuò)散連接的連接效率低、連接工藝條件苛刻等缺點(diǎn),在擴(kuò)散連接過(guò)程中施加交流電場(chǎng)和脈沖電場(chǎng),以優(yōu)化Si C/Ti擴(kuò)散連接工藝,降低擴(kuò)散連接溫度,改善接頭質(zhì)量。同時(shí),利用SEM、TEM、XRD等方法研究交流電場(chǎng)和脈沖電場(chǎng)對(duì)Si C/Ti擴(kuò)散連接界面反應(yīng)的影響規(guī)律和連接機(jī)理。交流電壓對(duì)SiC/Ti接頭顯微組織和力學(xué)性能有很大影響,交流電壓值與連接溫度,兩者共同作用影響反應(yīng)層的厚度,而反應(yīng)層厚度對(duì)接頭剪切性能影響存在最佳值。最佳工藝參數(shù)為950℃/7.5MPa/1.5h/交流電壓值400V,此時(shí)接頭剪切強(qiáng)度可達(dá)72.5MPa,比無(wú)電壓擴(kuò)散連接接頭強(qiáng)度提高59%,說(shuō)明施加交流電壓可以有效提高接頭質(zhì)量。電壓的方向?qū)缑孢B接情況有較大影響,負(fù)電壓抑制元素?cái)U(kuò)散,反應(yīng)層厚度降低,導(dǎo)致基體之間結(jié)合強(qiáng)度降低;正電壓促進(jìn)元素?cái)U(kuò)散,接頭質(zhì)量較好。但交流電壓疊加較大靜電壓時(shí),反應(yīng)層變厚,反應(yīng)層內(nèi)生成大量脆性化合物對(duì)接頭性能不利。采用正交試驗(yàn)獲得脈沖電場(chǎng)作用下各參數(shù)對(duì)接頭性能影響按脈沖幅度、占空比、頻率依次增大,且各脈沖參數(shù)存在交互作用。最佳脈沖工藝參數(shù)為脈沖幅度為400V,占空比為50%,頻率為500Hz,在此脈沖電場(chǎng)作用下,經(jīng)950℃/7.5MPa/1.5h擴(kuò)散連接接頭的剪切強(qiáng)度達(dá)到78.9MPa。對(duì)SiC/Ti界面微觀組織結(jié)構(gòu)進(jìn)行分析發(fā)現(xiàn),界面反應(yīng)生成相主要為T(mén)i C與Ti5Si3,接頭界面反應(yīng)的相組成結(jié)構(gòu)從Si C到Ti為:Si C/細(xì)晶區(qū)/(Ti C+Ti5Si3)/Ti C/Ti。Si C/Ti擴(kuò)散連接接頭的斷裂屬于脆性解理斷裂,整個(gè)斷面的裂紋擴(kuò)展路徑為:裂紋首先萌生在連接界面最薄弱的地方,接著在雙相區(qū)與Si C中反復(fù)擴(kuò)展,直至接頭被破壞。SiC與Ti形成可靠性連接的重要階段在于固相擴(kuò)散反應(yīng),即發(fā)生了反應(yīng)擴(kuò)散。與未施加電場(chǎng)的情況下相比,施加電場(chǎng)后反應(yīng)層各區(qū)的厚度均增加,電場(chǎng)提高了反應(yīng)擴(kuò)散的速率常數(shù),即在相同時(shí)間內(nèi),施加電場(chǎng)后反應(yīng)層更厚。通過(guò)熱力學(xué)分析,生成Ti C和Ti5Si3的化學(xué)反應(yīng)自由能遠(yuǎn)遠(yuǎn)小于0,因此該反應(yīng)在選用的試驗(yàn)條件下能夠自發(fā)進(jìn)行。由反應(yīng)的平衡常數(shù)Kθ值可以看出,當(dāng)反應(yīng)達(dá)到平衡時(shí),生成物的濃度很高,即反應(yīng)進(jìn)行的比較完全。
[Abstract]:SiC ceramics have excellent properties such as high temperature resistance, corrosion resistance and strong oxidation resistance. The excellent properties of ceramics and metals can be fully utilized when ceramic / metal composite structural parts are prepared by bonding method. It is of great significance to widen the application of ceramic materials. In this paper, sic / Ti composite members are fabricated by diffusion bonding method, and aiming at the disadvantages of low bonding efficiency and harsh bonding process conditions. In order to optimize the sic / Ti diffusion bonding process, reduce the diffusion bonding temperature and improve the quality of the joints, AC field and pulse electric field are applied in the diffusion bonding process. The influence of alternating current field and pulse electric field on the interfacial reaction of SiC/Ti diffusion bonding was studied by means of SEM-TEMX XRD. The AC voltage has a great influence on the microstructure and mechanical properties of SiC/Ti joint, and the AC voltage value and the connection temperature are also studied. The combination of the two influences the thickness of the reaction layer, The optimum process parameter is 950 鈩，

本文編號(hào)：1516880