本文選題：銀基釬料 + 雜質(zhì)元素��； 參考：《機(jī)械科學(xué)研究總院》2015年博士論文

【摘要】：近年來(lái),隨著釬焊材料應(yīng)用領(lǐng)域不斷擴(kuò)展和性能研究不斷深入,對(duì)釬料品質(zhì)的要求隨之不斷增加。然而,在釬料生產(chǎn)及后期服役過(guò)程中的共性問(wèn)題“微量雜質(zhì)元素”研究的系統(tǒng)性不夠。目前微量雜質(zhì)元素的研究工作已引起國(guó)內(nèi)外學(xué)者的重視,逐漸開展相關(guān)的研究工作,但針對(duì)雜質(zhì)元素鈣、碳、硫、氧對(duì)銀基釬料影響及釬料潔凈度的表征方法等仍未見系統(tǒng)研究和報(bào)道。課題依托國(guó)家973項(xiàng)目“潔凈鋼工藝仿真與連接界面結(jié)構(gòu)及性能表征研究”開展,采用光學(xué)顯微鏡、掃描電子顯微鏡、XPS和XRD等多種分析手段研究鈣、碳、硫、氧在銀基釬料中的存在形式及其對(duì)釬焊工藝性和釬焊性能影響作用機(jī)理,初步提出不同雜質(zhì)元素對(duì)釬料及釬焊性能影響規(guī)律,界定潔凈釬料,并用熵值表征了釬料潔凈度。研究表明：鈣元素使BAg45CuZn釬料三元共晶點(diǎn)E向Ag方向靠近,隨其含量的增加,釬料組織中銅基及銀基固溶體晶粒異常長(zhǎng)大,而銀基固溶體含量減少,層片狀共晶組織增多且其片間距減小。鈣主要存在于銀基固溶體和銅基固溶體的相界面處,易與銅生成高硬脆性、斜方晶格的α-CaCu金屬間化合物,且其較為活潑的化學(xué)性質(zhì),在氧作用下,使固溶在釬料中的鈣形成CaO阻流劑阻礙釬料流動(dòng),降低其與母材的潤(rùn)濕性能,最終導(dǎo)致釬焊性能下降。硫是破壞力極強(qiáng)的元素,在釬料表層形成Cu2S, ZnS, Ag2S等高熔點(diǎn)硫化物,釬料心部顯微組織形態(tài)雖未發(fā)生明顯變化,但硫原子向釬料心部進(jìn)行了擴(kuò)散,其在銀固溶體中的含量略低于銅固溶體。隨著硫含量的增加,釬料斷裂方式由韌性斷裂演變?yōu)榇嘈詳嗔?斷口處存在大量割裂基體連續(xù)性的粒狀硫化物。在釬焊溫度下,未熔融的硫化物增加釬料粘度,造成與母材界面張力增加,易形成未釬透缺欠,惡化釬焊性能。帶有軋制油的釬料會(huì)在其表面形成一層含碳層,根據(jù)軋制道次的不同,厚度將從0.5μm變化到7gm左右。碳在釬料表面主要以游離的碳分子和ZnC8、C2CdO4形式存在。在焊接的過(guò)程中,釬料內(nèi)游離碳分子和含碳化合物中部分未能及時(shí)上浮到表面而被包裹在釬料內(nèi)部；部分碳分子及含碳化合物隨著釬料的熔化開始上浮,最后這些顆粒物被液態(tài)釬料推到了鋪展最前沿,在液態(tài)釬料周圍形成一個(gè)包圍圈,阻礙釬料的鋪展；還有極少一部分游離的碳易與鋼中的Cr、Ni、Mn、Fe等形成了一些碳化物,但結(jié)合界面處的組織比較疏松,存在孔洞,致使接頭的抗拉強(qiáng)度降低。氧在釬料中主要以氧化物的形式存在,固溶和吸附的含量較低。隨著粉狀釬料氧含量的增加,粉末顆粒之間出現(xiàn)了一定的粘連,部分顆粒表面還出現(xiàn)了裂痕。利用高氏-洛侖茲方法分析發(fā)現(xiàn)釬料表層結(jié)構(gòu)由外向內(nèi)依次為自由水吸附層、碳?xì)溆袡C(jī)化合物污染層、氧化物層。同時(shí),釬料合金的固相線溫度及表觀活化能不斷升高,而潤(rùn)濕性和接頭強(qiáng)度不斷下降。釬焊接頭組織中的氧化夾雜物缺陷,在疲勞試驗(yàn)過(guò)程中易在此處形成裂紋源,致使接頭強(qiáng)度降低。針對(duì)銀基釬料,提出了“潔凈”釬料的概念及釬料流動(dòng)速率評(píng)價(jià)方法,在將釬焊工藝性評(píng)價(jià)規(guī)范由傳統(tǒng)的質(zhì)量-面積評(píng)價(jià)擴(kuò)展為質(zhì)量-面積-時(shí)間評(píng)價(jià)方面邁出了實(shí)質(zhì)性一步：用工藝熵值和性能熵值兩個(gè)參數(shù)定量表達(dá)釬料潔凈度,揭示了同成分同組織釬料性能迥異的內(nèi)在原因,初步建立了“潔凈”釬料表征體系,豐富了該領(lǐng)域的相關(guān)內(nèi)容。
[Abstract]:In recent years, with the continuous expansion of the application field of brazing materials and the deepening of the performance research, the requirements for the quality of the solder have been increasing. However, the systematicness of the study of "trace impurity elements" in the common problem in the process of the production and service of the brazing material is not enough. There is no systematic study and report on the influence of calcium, carbon, sulfur and oxygen on the influence of silver based filler metals and the cleanliness of the solder. The subject relies on the national 973 project, "the study of the process simulation of clean steel and the characterization of the connection interface structure and properties", and the use of optical microscopy and scanning electricity. The existence form of calcium, carbon, sulfur and oxygen in silver based solder and its influence mechanism on brazing process and brazing properties are studied by various analytical means such as SUBMICROSCOPE, XPS and XRD. The influence rules of different impurity elements on brazing properties and brazing properties are preliminarily proposed, clean solder is defined and the cleanliness of the filler metal is characterized by entropy value. With the increase of the content of the three element eutectic point E of the BAg45CuZn filler metal, the content of copper based and silver based solid solution in the solder is abnormal, but the content of the silver based solid solution decreases, the layer like eutectic structure increases and the interval between the pieces decreases. The calcium is mainly located at the interface of the silver based solid solution and the copper based solid solution, and is easily formed with copper. High hard brittleness, a -CaCu intermetallic compound of the inclined square lattice, and its more active chemical properties. Under the action of oxygen, the calcium forming CaO inhibitor in the solders prevents the flow of the solder, reduces its wettability with the parent material, and eventually leads to the decrease of brazing properties. Sulfur is a very strong breaking force, and forms Cu2S, ZnS, Ag2 on the surface of the solder. Although the microstructure morphology of the core of S and other high melting points is not obviously changed, the sulfur atom diffuses into the core of the brazing material, and its content in the silver solid solution is slightly lower than that of the copper solid solution. With the increase of the sulfur content, the fracture mode of the brazing material evolves from ductile fracture to brittle fracture, and there is a large number of fractured matrix continuity at the fracture surface. At the brazing temperature, the non fused sulfide increases the viscosity of the solder, resulting in an increase in the interfacial tension with the parent material, and the formation of a layer of carbon containing a layer on its surface. The thickness of the solder with rolling oil will form a layer of carbon in the surface of the rolling oil from 0.5 to 7gm. The carbon is on the surface of the solder. The free carbon molecules and ZnC8, C2CdO4 form exist mainly. During the welding process, the free carbon molecules and the parts of the carbon containing compounds in the solder are not floating to the surface in time and are wrapped in the filler metal; some carbon molecules and carbon containing compounds begin to float up with the melting of the solder, and finally these particles are pushed to the bed by liquid solder. At the forefront of the exhibition, a ring around the liquid filler metal is formed around the liquid solder, which hinders the spreading of the solder; and a few free carbon is easy to form some carbides with Cr, Ni, Mn, and Fe in the steel, but the microstructure at the interface is loose and has holes, causing the tensile strength of the joint to be reduced. Oxygen is mainly in the form of oxide in the solder. The content of solid solution and adsorption is low. With the increase of oxygen content of the powder filler metal, there are certain adhesions between the powder particles and some cracks on the surface of the particles. Using the method of the Kao's Lorentz method, it is found that the surface structure of the filler metal is from the outside to the inside of the free water adsorption layer, the hydrocarbon organic compound pollution layer and the oxide layer. At the time, the solid phase temperature and apparent activation energy of the brazing alloy are increasing, and the wettability and strength of the joint are decreasing. The defect of the oxide inclusions in the brazed joints is easy to form a crack source here in the fatigue test, which causes the joint strength to be reduced. The concept of "clean" solder and the flow of the brazing filler metal are proposed for the silver base solder. The method of rate evaluation has taken a substantial step in the evaluation of brazing technical specification from the traditional quality area evaluation to the quality area time evaluation. It quantificationally expresses the cleanliness of the solder by two parameters of entropy value and entropy value of the process, and reveals the inherent reasons for the very different performance of the same composition and the same organization. The "clean" solder characterization system enriches the relevant contents in this field.

【學(xué)位授予單位】：機(jī)械科學(xué)研究總院
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG425

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