鎂合金防腐復(fù)合涂層的制備及耐蝕性研究
發(fā)布時(shí)間：2018-12-16 07:11
【摘要】：鎂合金作為新世紀(jì)新型綠色材料,具有很多其它金屬無(wú)法比擬的優(yōu)點(diǎn),如密度小,強(qiáng)度高,電磁屏蔽好等特點(diǎn),在通訊、汽車(chē)、電子等行業(yè)具有很大的應(yīng)用潛力。但是,鎂合金的耐蝕性較差,這大大限制了鎂合金大范圍的應(yīng)用,如何提高鎂合金的耐蝕性成為鎂合金進(jìn)一步推廣應(yīng)用所要解決的首要問(wèn)題。為了使鎂合金的優(yōu)勢(shì)充分發(fā)揮,很多耐蝕涂層被研究開(kāi)發(fā)。如金屬鍍層、有機(jī)涂層、化學(xué)轉(zhuǎn)化膜、陽(yáng)極氧化等。但是,這幾種方法均有一些缺陷�；瘜W(xué)轉(zhuǎn)化膜制備方法簡(jiǎn)單,但是膜的致密性差,容易開(kāi)裂,無(wú)法阻止鎂合金基底的腐蝕;陽(yáng)極氧化能夠在鎂合金表面形成多孔的氧化膜,在一定程度上降低鎂合金的腐蝕速率,但是由于表面孔洞的存在,單層氧化層無(wú)法長(zhǎng)久保護(hù)鎂合金基底,腐蝕介質(zhì)易進(jìn)入孔洞腐蝕鎂合金基底;電鍍和化學(xué)鍍鍍層一般分為陽(yáng)極鍍層和陰極鍍層,最常見(jiàn)的鎂合金防腐的金屬鍍層為鎳磷合金鍍層,作為陰極鍍層的最大的缺點(diǎn)就是如果鍍層存在微孔將加速鎂合金基底的腐蝕,基底在很短時(shí)間內(nèi)產(chǎn)生穿孔,且施鍍步驟復(fù)雜,耗能大。本論文主要研究鎂合金防護(hù)的新方法,為鎂合金的防腐提供新思路,進(jìn)一步提高鎂合金的耐蝕性,擴(kuò)大其使用范圍。涂層的宏觀及微觀形貌分別用光學(xué)顯微鏡和場(chǎng)發(fā)射掃描電子顯微鏡(FESEM)表征。涂層成分及元素含量采用色散X射線(xiàn)光譜(EDS)測(cè)定。通過(guò)浸泡試驗(yàn)、電化學(xué)極化、電化學(xué)阻抗等測(cè)試方法表征涂層的形成機(jī)理及涂層的耐蝕性。主要研究?jī)?nèi)容如下:1.研究并討論了鎂合金化學(xué)鍍雙層鍍層的防護(hù)與腐蝕機(jī)理。針對(duì)當(dāng)前鎂合金化學(xué)鍍鎳存在的孔洞問(wèn)題,提出了雙層鍍施鍍方案,以化學(xué)鍍Ni-P層作為內(nèi)層,化學(xué)鍍Ni-B作為外層,研究了最佳工藝條件參數(shù)。采用鹽霧以及電化學(xué)手段對(duì)鍍層的腐蝕行為進(jìn)行了檢測(cè),并提出了雙層鍍層的腐蝕機(jī)理。2.開(kāi)發(fā)了非活性基底的一種非鈀活化工藝,并優(yōu)化了工藝條件,最終在微弧氧化層上獲得均勻致密的化學(xué)鍍鎳層。微弧氧化層作為內(nèi)層,具有多孔結(jié)構(gòu),能夠?yàn)榛瘜W(xué)鍍層提供足夠多的機(jī)械咬合點(diǎn),且在一定程度上減小鎂合金基底與化學(xué)鍍鎳層之間的電偶腐蝕的發(fā)生�；瘜W(xué)鍍鎳層作為外層能夠?qū)ξ⒒⊙趸瘜悠鸬椒饪椎男Ч?.研究了鎂合金表面超疏水鍍層的制備工藝,采用化學(xué)鍍和電鍍相結(jié)合的方法在鎂合金表面獲得疏水層,該涂層由內(nèi)層化學(xué)預(yù)鍍鎳,中間層電鍍銅和外層電鍍鎳層組成�；瘜W(xué)預(yù)鍍鎳使試樣表面電場(chǎng)分布相對(duì)均勻,電鍍銅層起到加厚鍍層及作為阻擋層的作用。電鍍鎳使得表面形成粗糙結(jié)構(gòu),而粗糙表面是超疏水結(jié)構(gòu)形成的一個(gè)重要因素。然后通過(guò)簡(jiǎn)單的浸泡方法對(duì)鍍層表面進(jìn)行修飾,獲得超疏水層。4.研究開(kāi)發(fā)了一種鎂合金化學(xué)電泳復(fù)合涂層方法。采用電化學(xué)氧化的方式使鎂合金表面形成氧化層,然后通過(guò)化學(xué)電泳的方式在鎂合金表面獲得一層致密的較厚的涂層。當(dāng)氧化試樣放入電泳漆中時(shí),氧化層的Mg O或者M(jìn)g(OH)2與電泳漆中的樹(shù)脂陽(yáng)離子發(fā)生反應(yīng),不溶性的樹(shù)脂沉積在試樣表面形成涂層。對(duì)涂層的結(jié)構(gòu)及耐蝕性進(jìn)行了實(shí)驗(yàn)研究。本論文在如下方面有創(chuàng)新性研究工作:(1)在鎂合金表面制備了高耐蝕性的Ni-B/Ni-P雙層鍍層,并探究了雙層鍍層高耐蝕性的原因。(2)采用一種新型的非活性基底活化劑,在鎂合金微弧氧化層上獲得了化學(xué)鍍鎳層,大大降低了活化劑成本。研究了新型活化劑的活化機(jī)理及所得到的復(fù)合涂層的腐蝕機(jī)理;(3)開(kāi)發(fā)了一種具有超疏水性質(zhì)的功能性鍍鎳層,對(duì)鍍層的結(jié)構(gòu)、耐蝕性及疏水機(jī)理進(jìn)行了探究。(4)開(kāi)發(fā)了一種鎂合金化學(xué)電泳復(fù)合涂層防護(hù)技術(shù),并對(duì)所得復(fù)合涂層的耐蝕性進(jìn)行了研究。
[Abstract]:As a new type of green material in the new century, the magnesium alloy has the advantages of many other metals, such as small density, high strength, good electromagnetic shielding and so on, and has great application potential in the fields of communication, automobile and electronics. However, the corrosion resistance of the magnesium alloy is poor, which greatly limits the application of the large range of the magnesium alloy, and how to improve the corrosion resistance of the magnesium alloy is the first problem to be solved by the further popularization and application of the magnesium alloy. In order to give full play to the advantages of the magnesium alloy, many corrosion-resistant coatings have been developed. such as a metal coating, an organic coating, a chemical conversion film, an anode oxidation, and the like. However, there are some drawbacks in these methods. The preparation method of the chemical conversion film is simple, but the compactness of the film is poor, the cracking is easy, the corrosion of the magnesium alloy substrate can not be prevented, the anodic oxidation can form a porous oxide film on the surface of the magnesium alloy, and the corrosion rate of the magnesium alloy can be reduced to a certain extent, but due to the existence of the surface hole, the single-layer oxide layer can not protect the magnesium alloy substrate for a long time, the corrosion medium is easy to enter the hole to erode the magnesium alloy substrate, the electroplating and the chemical plating plating layer are generally divided into an anode plating layer and a cathode plating layer, and the most common corrosion-resistant metal plating layer of the magnesium alloy is a nickel-phosphorus alloy coating, the biggest disadvantage of the cathode coating is that if the coating is present with a micro-hole, the corrosion of the magnesium alloy substrate is accelerated, the substrate is perforated in a very short time, and the plating step is complex and the energy consumption is large. This paper mainly studies the new method of magnesium alloy protection, and provides a new thought for the corrosion protection of the magnesium alloy, and further improves the corrosion resistance of the magnesium alloy and expands the application range thereof. The macroscopic and micro-morphology of the coatings were characterized by an optical microscope and a field emission scanning electron microscope (FESEM), respectively. The content of the coating and the content of the element were determined by dispersive X-ray spectroscopy (EDS). The formation mechanism of the coating and the corrosion resistance of the coating were characterized by immersion test, electrochemical polarization and electrochemical impedance. The main content of the study is as follows: 1. The protection and corrosion mechanism of magnesium alloy electroless plating double-layer coating was studied and discussed. In order to solve the problem of the existing holes in the electroless nickel plating of the magnesium alloy, a double-layer plating scheme was proposed, and the optimum process condition parameters were studied by electroless Ni-P layer as the inner layer and the electroless Ni-B as the outer layer. The corrosion behavior of the coating was tested by salt spray and electrochemical method, and the corrosion mechanism of the double-layer coating was put forward. A non-active activation process for inactive substrates was developed, and the process conditions were optimized, and a homogeneous and dense electroless nickel plating layer was finally obtained on the micro-arc oxidation layer. the micro-arc oxidation layer is used as an inner layer and has a porous structure, so that a sufficient mechanical bite point can be provided for the chemical plating layer, and the occurrence of the electric coupling corrosion between the magnesium alloy substrate and the chemical nickel-plating layer is reduced to a certain extent. the chemical nickel-plating layer can be used as the outer layer to effect the micro-arc oxidation layer as a sealing hole. The preparation process of the super-hydrophobic coating on the surface of the magnesium alloy was studied. The hydrophobic layer was obtained on the surface of the magnesium alloy by the combination of electroless plating and electroplating. The coating was composed of the inner layer of chemical pre-plating, the intermediate layer of copper plating and the nickel layer of the outer layer. the chemical pre-nickel plating makes the electric field distribution of the surface of the sample to be relatively uniform, and the electroplated copper layer plays a role of thickening the plating layer and serving as a barrier layer. Electroplated nickel causes the surface to form a rough structure, and the rough surface is an important factor in the formation of super-hydrophobic structures. and then the surface of the plating layer is modified by a simple soaking method to obtain the super-hydrophobic layer. A method for composite coating of magnesium alloy by chemical electrophoresis was developed. the surface of the magnesium alloy is formed into an oxide layer by means of an electrochemical oxidation, and then a dense thick coating is obtained on the surface of the magnesium alloy by means of chemical electrophoresis. When the oxidation sample is put into the electrophoretic paint, the Mg O or Mg (OH) 2 of the oxide layer reacts with the resin cation in the electrophoretic paint, and the insoluble resin is deposited on the surface of the sample to form a coating. The structure and corrosion resistance of the coating were studied. The paper has the innovative research work in the following aspects: (1) The Ni-B/ Ni-P double-layer coating with high corrosion resistance is prepared on the surface of the magnesium alloy, and the reason of the high corrosion resistance of the double-layer coating is also investigated. and (2) a novel non-active base activator is adopted, a chemical nickel-plating layer is obtained on the magnesium alloy micro-arc oxidation layer, and the cost of the activator is greatly reduced. The activation mechanism of the new activator and the corrosion mechanism of the composite coating were studied. (3) a functional nickel-plated layer with super-hydrophobic property was developed, and the structure, corrosion resistance and hydrophobic mechanism of the coating were explored. (4) The protective technology of magnesium alloy chemical electrophoresis composite coating was developed, and the corrosion resistance of the obtained composite coating was studied.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TG174.4
本文編號(hào)：2381974
[Abstract]:As a new type of green material in the new century, the magnesium alloy has the advantages of many other metals, such as small density, high strength, good electromagnetic shielding and so on, and has great application potential in the fields of communication, automobile and electronics. However, the corrosion resistance of the magnesium alloy is poor, which greatly limits the application of the large range of the magnesium alloy, and how to improve the corrosion resistance of the magnesium alloy is the first problem to be solved by the further popularization and application of the magnesium alloy. In order to give full play to the advantages of the magnesium alloy, many corrosion-resistant coatings have been developed. such as a metal coating, an organic coating, a chemical conversion film, an anode oxidation, and the like. However, there are some drawbacks in these methods. The preparation method of the chemical conversion film is simple, but the compactness of the film is poor, the cracking is easy, the corrosion of the magnesium alloy substrate can not be prevented, the anodic oxidation can form a porous oxide film on the surface of the magnesium alloy, and the corrosion rate of the magnesium alloy can be reduced to a certain extent, but due to the existence of the surface hole, the single-layer oxide layer can not protect the magnesium alloy substrate for a long time, the corrosion medium is easy to enter the hole to erode the magnesium alloy substrate, the electroplating and the chemical plating plating layer are generally divided into an anode plating layer and a cathode plating layer, and the most common corrosion-resistant metal plating layer of the magnesium alloy is a nickel-phosphorus alloy coating, the biggest disadvantage of the cathode coating is that if the coating is present with a micro-hole, the corrosion of the magnesium alloy substrate is accelerated, the substrate is perforated in a very short time, and the plating step is complex and the energy consumption is large. This paper mainly studies the new method of magnesium alloy protection, and provides a new thought for the corrosion protection of the magnesium alloy, and further improves the corrosion resistance of the magnesium alloy and expands the application range thereof. The macroscopic and micro-morphology of the coatings were characterized by an optical microscope and a field emission scanning electron microscope (FESEM), respectively. The content of the coating and the content of the element were determined by dispersive X-ray spectroscopy (EDS). The formation mechanism of the coating and the corrosion resistance of the coating were characterized by immersion test, electrochemical polarization and electrochemical impedance. The main content of the study is as follows: 1. The protection and corrosion mechanism of magnesium alloy electroless plating double-layer coating was studied and discussed. In order to solve the problem of the existing holes in the electroless nickel plating of the magnesium alloy, a double-layer plating scheme was proposed, and the optimum process condition parameters were studied by electroless Ni-P layer as the inner layer and the electroless Ni-B as the outer layer. The corrosion behavior of the coating was tested by salt spray and electrochemical method, and the corrosion mechanism of the double-layer coating was put forward. A non-active activation process for inactive substrates was developed, and the process conditions were optimized, and a homogeneous and dense electroless nickel plating layer was finally obtained on the micro-arc oxidation layer. the micro-arc oxidation layer is used as an inner layer and has a porous structure, so that a sufficient mechanical bite point can be provided for the chemical plating layer, and the occurrence of the electric coupling corrosion between the magnesium alloy substrate and the chemical nickel-plating layer is reduced to a certain extent. the chemical nickel-plating layer can be used as the outer layer to effect the micro-arc oxidation layer as a sealing hole. The preparation process of the super-hydrophobic coating on the surface of the magnesium alloy was studied. The hydrophobic layer was obtained on the surface of the magnesium alloy by the combination of electroless plating and electroplating. The coating was composed of the inner layer of chemical pre-plating, the intermediate layer of copper plating and the nickel layer of the outer layer. the chemical pre-nickel plating makes the electric field distribution of the surface of the sample to be relatively uniform, and the electroplated copper layer plays a role of thickening the plating layer and serving as a barrier layer. Electroplated nickel causes the surface to form a rough structure, and the rough surface is an important factor in the formation of super-hydrophobic structures. and then the surface of the plating layer is modified by a simple soaking method to obtain the super-hydrophobic layer. A method for composite coating of magnesium alloy by chemical electrophoresis was developed. the surface of the magnesium alloy is formed into an oxide layer by means of an electrochemical oxidation, and then a dense thick coating is obtained on the surface of the magnesium alloy by means of chemical electrophoresis. When the oxidation sample is put into the electrophoretic paint, the Mg O or Mg (OH) 2 of the oxide layer reacts with the resin cation in the electrophoretic paint, and the insoluble resin is deposited on the surface of the sample to form a coating. The structure and corrosion resistance of the coating were studied. The paper has the innovative research work in the following aspects: (1) The Ni-B/ Ni-P double-layer coating with high corrosion resistance is prepared on the surface of the magnesium alloy, and the reason of the high corrosion resistance of the double-layer coating is also investigated. and (2) a novel non-active base activator is adopted, a chemical nickel-plating layer is obtained on the magnesium alloy micro-arc oxidation layer, and the cost of the activator is greatly reduced. The activation mechanism of the new activator and the corrosion mechanism of the composite coating were studied. (3) a functional nickel-plated layer with super-hydrophobic property was developed, and the structure, corrosion resistance and hydrophobic mechanism of the coating were explored. (4) The protective technology of magnesium alloy chemical electrophoresis composite coating was developed, and the corrosion resistance of the obtained composite coating was studied.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TG174.4
【參考文獻(xiàn)】
相關(guān)期刊論文 前2條
1 王寶剛;王旭;周吉學(xué);張國(guó)福;唐守秋;劉運(yùn)騰;李衛(wèi)紅;;耐熱鎂合金的研究進(jìn)展[J];山東科學(xué);2013年03期
2 唐鋒;胡光輝;黃華娥;潘湛昌;魏志鋼;曾海霞;;化學(xué)鍍鎳層無(wú)鉻鈍化工藝的研究[J];電鍍與精飾;2012年05期
，本文編號(hào)：2381974
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