6061和4043鋁合金在不同金屬表面的潤濕行為及界面結(jié)構(gòu)
發(fā)布時(shí)間：2019-04-16 15:44
【摘要】：鋁合金以其優(yōu)良的抗氧化性能而被廣泛應(yīng)用于熱浸鍍工藝中的鍍層材料。以鋼和鈦?zhàn)鳛榛w,通過熱浸鋁工藝得到的鍍層不但可以實(shí)現(xiàn)材料表面的室溫抗腐蝕性而且可以提高材料高溫下的抗氧化性。而在銅表面熱浸鍍鋁并結(jié)合半固態(tài)連接可以避免Al-Cu連接過程中過多脆性相的產(chǎn)生,實(shí)現(xiàn)Al-Cu復(fù)合材料的有效連接。熱浸鋁工藝的實(shí)現(xiàn)及鍍層質(zhì)量的控制與鋁合金在基體表面的潤濕性密切相關(guān)。同時(shí)異種金屬連接過程中釬料對(duì)母材良好的潤濕性是獲得優(yōu)質(zhì)焊接接頭的重要因素之一。因此,本課題通過研究鋁合金與T2銅、Q235鋼、TC4鈦合金及TA2純鈦的潤濕行為及界面結(jié)構(gòu),探討界面反應(yīng)與潤濕性及鋪展動(dòng)力學(xué)間的相互聯(lián)系。研究內(nèi)容有望進(jìn)一步豐富上述基體熱浸鋁工藝及異種金屬連接過程中釬料對(duì)母材潤濕性的相關(guān)基礎(chǔ)理論。首先,研究了熔融6061和4043鋁合金分別在T2銅表面的潤濕行為,研究表明:該體系屬于典型的溶解潤濕,在650~700 oC,潤濕性與溫度存在典型的相互依賴,隨著溫度升高最終潤濕性逐漸改善;在700~750 oC,隨著溫度升高潤濕性無明顯改善,最終平衡接觸角均在21o左右;界面分層現(xiàn)象可由溶解析出理論解釋,整個(gè)界面呈三層,依次為α2 Al-Cu固溶體、δAl-Cu固溶體及AlCu金屬間化合物;三相線區(qū)域熔融鋁合金含量相對(duì)較少,隨著Cu的溶解更容易達(dá)到飽和,并析出金屬間化合物;金屬間化合物產(chǎn)生后阻礙三相線區(qū)域固-液界面物質(zhì)交流,同時(shí)阻礙熔滴鋪展,從而抑制潤濕;兩者體系的鋪展動(dòng)力學(xué)均可由溶解過程控制潤濕模型描述,6061和4043鋁熔滴在基板表面呈非線性鋪展,潤濕激活能分別為52 kJ/mol和57 kJ/mol。其次,研究了熔融6061和4043鋁合金在Q235鋼、TC4鈦合金及TA2純鈦表面的潤濕行為,研究表明:上述體系均為典型的反應(yīng)潤濕,最終潤濕性與溫度存在典型的相互依賴關(guān)系,隨著溫度升高潤濕性明顯改善;鋁合金中微量的Si、Mg導(dǎo)致界面結(jié)構(gòu)及最終潤濕性產(chǎn)生差異,Si在界面富集,并且滿足熱力學(xué)條件;界面處富Si的致密層(Fe2(Al1-xSix)5、Ti7Al5Si12)產(chǎn)生后阻礙三相線區(qū)域固-液界面物質(zhì)交流,從而抑制潤濕;而Ti7Al5Si12不穩(wěn)定,隨著溫度升高,致密的Ti7Al5Si12逐漸分解,同時(shí)在三相線區(qū)域產(chǎn)生疏松的Al3Ti金屬間化合物,疏松相的產(chǎn)生能夠破除基板表面的氧化膜,促進(jìn)鋁合金熔滴與基板發(fā)生反應(yīng),從而促進(jìn)潤濕;Mg以蒸汽的形式揮發(fā)后包裹在三相線附近充當(dāng)氣相釬劑(還原劑),還原基板表面的氧化膜,使得基板表面呈金屬性,熔滴與潔凈的基板接觸并發(fā)生反應(yīng),同時(shí)三相線區(qū)域產(chǎn)生疏松的FeAl3及Al3Ti,疏松相產(chǎn)生后能夠破除基板表面的氧化膜,促進(jìn)潤濕;鋪展動(dòng)力學(xué)均可由典型的反應(yīng)產(chǎn)物控制潤濕模型描述,6061鋁合金在Q235鋼表面呈線性鋪展,在TC4鈦合金及TA2純鈦表面先呈非線性鋪展,后呈線性鋪展;而4043鋁合金在Q235鋼、TC4鈦合金及TA2純鈦表面均以非線性鋪展為主,潤濕激活能與界面反應(yīng)吉布斯自由能相關(guān)。最后,上述反應(yīng)潤濕體系均出現(xiàn)明顯的前驅(qū)膜,前驅(qū)膜與溫度存在相互依賴關(guān)系,溫度越高前驅(qū)膜越寬;同時(shí),前驅(qū)膜的出現(xiàn)總是伴隨著較好的最終潤濕性,形成機(jī)制為“皮下滲透”機(jī)制。
[Abstract]:The aluminum alloy is widely used in the coating material in the hot-dip coating process with its excellent oxidation resistance. By using the steel and the titanium as the matrix, the coating obtained by the hot-dip aluminum process not only can realize the room-temperature corrosion resistance of the surface of the material, but also can improve the oxidation resistance of the material at high temperature. And the hot-dip aluminizing on the surface of the copper and the semi-solid connection can avoid the generation of the excessive brittle phase in the Al-Cu connection process and realize the effective connection of the Al-Cu composite material. The realization of the hot-dip aluminum process and the control of the coating quality are closely related to the wettability of the aluminum alloy on the surface of the substrate. At the same time, the good wetting of the base material to the base metal during the connection of the dissimilar metal is one of the important factors to obtain the high-quality welded joint. In this paper, the wetting behavior and interface structure of aluminum alloy and T2 copper, Q235 steel, TC4 titanium alloy and TA2 pure titanium are studied, and the contact between the interface reaction and the wettability and the spreading dynamics is discussed. The research contents are expected to further enrich the basic theory of the wettability of the base metal in the hot-dip aluminum technology and the dissimilar metal connecting process. First, the wetting behavior of the molten 6061 and 4043 aluminum alloy on the surface of the T2 copper is studied. The results show that the system is typical of the dissolution and wetting, and the wettability and the temperature are typical in the range of 650-700 oC, and the wettability is gradually improved with the increase of the temperature. The final equilibrium contact angle is about 21 o as the temperature increase wettability is not obviously improved, and the interface layering phenomenon can be explained by the dissolution and precipitation theory, and the whole interface is three layers, and the whole interface is a 2-Al-Cu solid solution, an Al-Cu solid solution and an AlCu intermetallic compound; the content of the molten aluminum alloy in the three-phase line region is relatively small, and the saturation is more easily achieved with the dissolution of the Cu, and the intermetallic compound is precipitated; after the intermetallic compound is generated, the material exchange of the solid-liquid interface of the three-phase line region is prevented, and the droplet spreading is prevented, and the wetting is inhibited; The spreading kinetics of the two systems can be described by the dissolution process control and wetting model,6061 and 4043 aluminum droplets are non-linearly spread on the surface of the substrate, and the wetting activation energy is 52 kJ/ mol and 57 kJ/ mol, respectively. The wetting behavior of molten 6061 and 4043 aluminum alloy on the surface of Q235 steel, TC4 titanium alloy and TA2 pure titanium is studied. The results show that the system is typical of reactive wetting, and the final wettability and temperature are of typical interdependency, and the wettability is improved obviously with the increase of temperature. The micro-Si and Mg in the aluminum alloy lead to the difference of the interface structure and the final wettability, and the Si is rich in the interface, and the thermodynamic condition is satisfied; the Si-rich dense layer (Fe 2 (Al1-xSix)5, Ti7Al5Si12) at the interface blocks the material exchange of the solid-liquid interface of the three-phase line, thereby inhibiting the wetting; Ti7Al5Si12 is unstable, and as the temperature increases, the dense Ti7Al5Si12 is gradually decomposed, and a loose Al3Ti intermetallic compound is generated in the three-phase line region, and the formation of the loose phase can break the oxide film on the surface of the substrate, and promote the reaction between the molten drop of the aluminum alloy and the substrate, thereby promoting the wetting; The Mg is volatilized in the form of steam, and is wrapped in the vicinity of the three-phase line to act as a gas-phase entrainer (reducing agent), and the oxide film on the surface of the substrate is reduced, so that the surface of the substrate is metallic, the molten drop is in contact with the clean substrate and reacts, and simultaneously the three-phase line region produces loose FeAl3 and Al3Ti, the oxidation film on the surface of the substrate can be broken after the loose phase is generated, and the wetting is promoted; the spreading kinetics can be described by a typical reaction product control wetting model; the 6061 aluminum alloy is linearly spread on the surface of the Q235 steel; The surface of the 4043 aluminum alloy in Q235 steel, TC4 titanium alloy and TA2 pure titanium is mainly non-linear spread, and the wetting activation energy can be related to the Gibbs free energy of the interface reaction. Finally, the above-mentioned reaction wetting system has obvious precursor film, the precursor film and the temperature are interdependent, the higher the temperature is, the wider the precursor film is, and at the same time, the appearance of the precursor film is always accompanied by better final wettability, and the forming mechanism is the "Subcutaneous penetration" mechanism.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG174.44
本文編號(hào)：2458897
[Abstract]:The aluminum alloy is widely used in the coating material in the hot-dip coating process with its excellent oxidation resistance. By using the steel and the titanium as the matrix, the coating obtained by the hot-dip aluminum process not only can realize the room-temperature corrosion resistance of the surface of the material, but also can improve the oxidation resistance of the material at high temperature. And the hot-dip aluminizing on the surface of the copper and the semi-solid connection can avoid the generation of the excessive brittle phase in the Al-Cu connection process and realize the effective connection of the Al-Cu composite material. The realization of the hot-dip aluminum process and the control of the coating quality are closely related to the wettability of the aluminum alloy on the surface of the substrate. At the same time, the good wetting of the base material to the base metal during the connection of the dissimilar metal is one of the important factors to obtain the high-quality welded joint. In this paper, the wetting behavior and interface structure of aluminum alloy and T2 copper, Q235 steel, TC4 titanium alloy and TA2 pure titanium are studied, and the contact between the interface reaction and the wettability and the spreading dynamics is discussed. The research contents are expected to further enrich the basic theory of the wettability of the base metal in the hot-dip aluminum technology and the dissimilar metal connecting process. First, the wetting behavior of the molten 6061 and 4043 aluminum alloy on the surface of the T2 copper is studied. The results show that the system is typical of the dissolution and wetting, and the wettability and the temperature are typical in the range of 650-700 oC, and the wettability is gradually improved with the increase of the temperature. The final equilibrium contact angle is about 21 o as the temperature increase wettability is not obviously improved, and the interface layering phenomenon can be explained by the dissolution and precipitation theory, and the whole interface is three layers, and the whole interface is a 2-Al-Cu solid solution, an Al-Cu solid solution and an AlCu intermetallic compound; the content of the molten aluminum alloy in the three-phase line region is relatively small, and the saturation is more easily achieved with the dissolution of the Cu, and the intermetallic compound is precipitated; after the intermetallic compound is generated, the material exchange of the solid-liquid interface of the three-phase line region is prevented, and the droplet spreading is prevented, and the wetting is inhibited; The spreading kinetics of the two systems can be described by the dissolution process control and wetting model,6061 and 4043 aluminum droplets are non-linearly spread on the surface of the substrate, and the wetting activation energy is 52 kJ/ mol and 57 kJ/ mol, respectively. The wetting behavior of molten 6061 and 4043 aluminum alloy on the surface of Q235 steel, TC4 titanium alloy and TA2 pure titanium is studied. The results show that the system is typical of reactive wetting, and the final wettability and temperature are of typical interdependency, and the wettability is improved obviously with the increase of temperature. The micro-Si and Mg in the aluminum alloy lead to the difference of the interface structure and the final wettability, and the Si is rich in the interface, and the thermodynamic condition is satisfied; the Si-rich dense layer (Fe 2 (Al1-xSix)5, Ti7Al5Si12) at the interface blocks the material exchange of the solid-liquid interface of the three-phase line, thereby inhibiting the wetting; Ti7Al5Si12 is unstable, and as the temperature increases, the dense Ti7Al5Si12 is gradually decomposed, and a loose Al3Ti intermetallic compound is generated in the three-phase line region, and the formation of the loose phase can break the oxide film on the surface of the substrate, and promote the reaction between the molten drop of the aluminum alloy and the substrate, thereby promoting the wetting; The Mg is volatilized in the form of steam, and is wrapped in the vicinity of the three-phase line to act as a gas-phase entrainer (reducing agent), and the oxide film on the surface of the substrate is reduced, so that the surface of the substrate is metallic, the molten drop is in contact with the clean substrate and reacts, and simultaneously the three-phase line region produces loose FeAl3 and Al3Ti, the oxidation film on the surface of the substrate can be broken after the loose phase is generated, and the wetting is promoted; the spreading kinetics can be described by a typical reaction product control wetting model; the 6061 aluminum alloy is linearly spread on the surface of the Q235 steel; The surface of the 4043 aluminum alloy in Q235 steel, TC4 titanium alloy and TA2 pure titanium is mainly non-linear spread, and the wetting activation energy can be related to the Gibbs free energy of the interface reaction. Finally, the above-mentioned reaction wetting system has obvious precursor film, the precursor film and the temperature are interdependent, the higher the temperature is, the wider the precursor film is, and at the same time, the appearance of the precursor film is always accompanied by better final wettability, and the forming mechanism is the "Subcutaneous penetration" mechanism.
【學(xué)位授予單位】：蘭州理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG174.44
【引證文獻(xiàn)】
相關(guān)碩士學(xué)位論文 前1條
1 李旭賓;半導(dǎo)體激光與TIG電弧復(fù)合熱源的熔覆成形機(jī)理研究[D];蘭州理工大學(xué);2018年
，本文編號(hào)：2458897
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