【摘要】：目前金屬與石墨的連接廣泛應(yīng)用于電器行業(yè)中,電器設(shè)備的核心部件換向器中更需要實(shí)現(xiàn)銅與石墨的連接。石墨與銅的連接通常是在真空或者惰性氣體的保護(hù)環(huán)境下進(jìn)行,但受爐體尺寸大小的限制,很難在工業(yè)上實(shí)現(xiàn)批量生產(chǎn)。隨著超聲波輔助釬焊技術(shù)的出現(xiàn),使銅與石墨在大氣環(huán)境下的連接成為可能。本文采用了超聲波輔助活性釬焊技術(shù),選用并研制了兩種活性釬料:高溫的Ag-Cu-Zn-Ti釬料和低溫的Sn-Ag-Cu-Ti釬料。分析了超聲波在釬焊過(guò)程中的作用,研究了釬焊工藝及釬焊工藝參數(shù)對(duì)接頭力學(xué)性能的影響,并對(duì)連接機(jī)理進(jìn)行了探討。研究結(jié)果表明:采用Ag-Cu-Zn-Ti釬料,超聲波輔助活性釬焊技術(shù)可以實(shí)現(xiàn)大氣條件下銅與石墨的連接。釬焊溫度是接頭質(zhì)量的重要影響因素,在較高的溫度下施焊時(shí),金屬母材和活性釬料均氧化嚴(yán)重,增加了除去氧化膜的難度,使釬焊困難。對(duì)施加2 s超聲波作用得到的釬焊接頭進(jìn)行微觀組織分析,發(fā)現(xiàn)釬縫內(nèi)部靠石墨側(cè)存在大量破碎的氧化膜,隨著超聲波作用時(shí)間的延長(zhǎng),釬縫內(nèi)部的氧化膜逐漸減少,當(dāng)超聲波作用10 s時(shí),釬縫中的氧化膜完全消失,形成了較好的接頭。釬焊接頭的組織組成從銅側(cè)依次為銅/銅鋅合金/銀基固溶體+銅基固溶體/Ti C反應(yīng)層/石墨,釬料與石墨側(cè)的連接主要是反應(yīng)潤(rùn)濕連接。增加超聲作用時(shí)間與提高釬焊溫度會(huì)促使界面反應(yīng)層Ti C的生長(zhǎng),但其不能持續(xù)增加。研究還發(fā)現(xiàn),超聲波的施加時(shí)間影響著釬焊接頭的剪切性能,施加超聲波不超過(guò)10 s時(shí),超聲波有提高接頭強(qiáng)度的作用,如果超聲波作用再持續(xù)施加,反而會(huì)使接頭剪切強(qiáng)度下降。最佳的工藝條件為釬焊溫度820℃、超聲波作用時(shí)間10 s、保溫10 min,在此釬焊條件下,釬焊接頭強(qiáng)度達(dá)到最大值18 MPa采用Sn-Ag-Cu-Ti活性釬料,在大氣條件下也能借助超聲波輔助實(shí)現(xiàn)銅與石墨的連接。在超聲波作用2 s至20 s的過(guò)程中,在釬縫內(nèi)部均沒(méi)有發(fā)現(xiàn)有氧化膜的存在。對(duì)釬焊接頭進(jìn)行分析時(shí)并未發(fā)現(xiàn)釬料與石墨發(fā)生冶金結(jié)合。超聲波作用20 s時(shí),在石墨側(cè)沒(méi)有Ti C反應(yīng)層的形成,釬料與石墨的連接主要是在超聲波的驅(qū)動(dòng)作用下,釬料向石墨內(nèi)部孔洞中的流動(dòng),冷卻至室溫形成的機(jī)械連接。釬焊接頭的界面組織從銅側(cè)依次為Cu/Cu3Sn金屬間化合物層/Cu6Sn5金屬間化合物/Sn-Ti合金、Sn-Ag合金與少量Cu-Ti合金/石墨。當(dāng)釬焊溫度為450℃,施加12s的超聲波作用時(shí),得到的接頭強(qiáng)度最大,為16 MPa。采用這種低溫活性釬料釬焊銅與石墨得到的釬焊接頭,剪切強(qiáng)度大于母材石墨本身。
[Abstract]:At present, the connection between metal and graphite is widely used in the electrical industry, and the connection between copper and graphite is more necessary in the commutator, which is the core component of electrical equipment. The connection between graphite and copper is usually carried out in vacuum or noble gas protection environment, but due to the size of furnace body, it is difficult to realize mass production in industry. With the emergence of ultrasonic assisted brazing technology, the connection between copper and graphite in atmospheric environment is possible. In this paper, two kinds of active solder, high temperature Ag-Cu-Zn-Ti solder and low temperature Sn-Ag-Cu-Ti solder, have been selected and developed by using ultrasonic assisted active brazing technology. The function of ultrasonic wave in brazing process is analyzed, the influence of brazing process and brazing process parameters on the mechanical properties of the joint is studied, and the bonding mechanism is discussed. The results show that the connection between copper and graphite can be realized by using Ag-Cu-Zn-Ti solder and ultrasonic assisted active brazing technology. Brazing temperature is an important factor affecting the quality of joints. When welding at higher temperatures, both the base metal and the active solder are oxidized seriously, which makes it difficult to remove the oxide film and make brazing difficult. The microstructure of the brazed joint subjected to 2 s ultrasonic action is analyzed. It is found that there are a large number of broken oxide films on the graphite side of the brazing seam. With the prolongation of ultrasonic action time, the oxide film in the brazing joint decreases gradually. When the ultrasonic wave is applied for 10 s, the oxide film in the brazing seam disappears completely and a good joint is formed. The microstructure composition of brazing joint is copper / copper-zinc alloy / silver-based solid solution copper-based solid solution / Ti C reaction layer / graphite from copper side, and the connection between solder and graphite side is mainly reactive wetting connection. Increasing ultrasonic action time and brazing temperature will promote the growth of interface reaction layer Ti C, but it can not increase continuously. It is also found that the shear properties of brazed joints are affected by the application time of ultrasonic wave. When the ultrasonic wave is applied less than 10 s, the ultrasonic wave can improve the strength of the joint, and if the ultrasonic action continues to be applied, On the contrary, the shear strength of the joint will be reduced. The optimum technological conditions are as follows: brazing temperature 820 鈩，

本文編號(hào)：2476766