本文選題：銅包鎢粉 + 粉體電鍍��； 參考：《湖南大學(xué)》2014年碩士論文

【摘要】：銅包鎢粉是廣泛應(yīng)用于電接觸材料、電極材料、軍工材料、高密度合金以及電子封裝和熱沉材料等領(lǐng)域的先進(jìn)包覆粉體復(fù)合材料。采用電鍍的方法制備銅包鎢粉克服了傳統(tǒng)的化學(xué)鍍方法出現(xiàn)的施鍍效率低，鍍液循環(huán)性差，產(chǎn)品不純，環(huán)境污染等缺陷。 本文以粒徑分布3-16m鎢粉為基體，采用間歇電鍍的方法制備銅包鎢粉，研究了電鍍制備銅包鎢粉的工藝和大超電勢下銅的成核機(jī)理。并研究了銅包鎢粉對鎢銅復(fù)合材料顯微組織結(jié)構(gòu)及性能的影響。采用掃描電鏡（SEM）、能譜分析（EDX）、X射線衍射儀（XRD）等測試手段對復(fù)合粉體表面形貌、鍍層表面的元素及相組成進(jìn)行了分析。具體研究成果如下： 1、獲得了合適的電鍍工藝，CuSO460g dm 3，濃H2SO440cm3dm 3，十二烷基硫酸鈉0.1g dm3，控制8-12g·dm3鎢粉裝載量，用12-16A·dm2陰極電流密度，在20-30h1攪拌頻率下對鎢粉施鍍，可以制得包覆完好的銅包鎢粉復(fù)合粉體。鍍層平均厚度約為2.5m，銅含量可達(dá)到54.3wt%，鎢銅復(fù)合粉體的制備效率大大提高。 2、銅離子在鎢粉表面能量低的地方呈點狀沉積，然后不斷生長，最后擴(kuò)展到整個鎢粉表面形成包覆層，鍍層均勻致密；EDX和XRD結(jié)果顯示復(fù)合粉體中無雜質(zhì)存在，表面的銅鍍層以晶態(tài)形式存在，鍍層較厚且包覆完整。 3、施加合適的電流密度和攪拌頻率能夠有效地控制銅在粉體上電鍍，合適的攪拌頻率，可以避免電鍍過程鎢粉的團(tuán)聚現(xiàn)象，將電鍍鎢粉打碎并重新分散，，促使內(nèi)層粉體與表層粉體不斷地變化、轉(zhuǎn)換，保證粉體受鍍的均勻性。 4、大超電勢下銅的成核遵循瞬時成核機(jī)理，且沉積電勢越負(fù)，銅的成核越向瞬時成核曲線方向偏移。大的電流密度下銅的成核密度大，有利于在大比表面積的鎢粉表面形成均勻致密的銅鍍層。 5、研究了有機(jī)添加劑在電解液中的作用，適量聚乙二醇能有效增大陰極極化，增大電化學(xué)反應(yīng)電阻，提高極化超電勢，使銅電結(jié)晶的成核尺寸減小，從而獲得均勻致密的銅鍍層。 6、銅包鎢粉能夠改善鎢銅復(fù)合材料的組織均勻性，降低材料的孔隙度。銅基體形成連續(xù)三維導(dǎo)電網(wǎng)絡(luò)結(jié)構(gòu)，鎢顆粒更趨彌散，增強(qiáng)了銅、鎢間的界面結(jié)合力。鎢銅復(fù)合材料的密度、硬度和導(dǎo)熱導(dǎo)電性顯著提高，熱膨脹系數(shù)明顯降低，鎢銅復(fù)合材料的性能有顯著提高。
[Abstract]:Copper coated tungsten powder is an advanced coated powder composite which is widely used in the fields of electrical contact materials, electrode materials, military materials, high density alloys, electronic packaging and heat sink materials. The preparation of copper coated tungsten powder by electroplating overcomes the disadvantages of the traditional electroless plating methods such as low plating efficiency, poor cycling of bath, impure products and environmental pollution. In this paper, copper coated tungsten powder was prepared by intermittent electroplating using 3-16m tungsten powder with particle size distribution as substrate. The preparation process of copper coated tungsten powder and the nucleation mechanism of copper under large superpotential were studied. The effect of copper-coated tungsten powder on microstructure and properties of tungsten-copper composite was studied. The surface morphology, elements and phase composition of the composite powder were analyzed by means of SEM and EDXX X ray diffractometer (XRD). The specific research results are as follows: 1. The suitable electroplating process of CuSO4 60g dm ~ (3), concentrated H _ 2SO _ 4 _ (40) cm ~ (3) cm ~ (-3), sodium dodecyl sulfate 0.1 g / dm ~ (3), controlling the loading amount of 8-12g dm3 tungsten powder, using 12-16A dm2 cathode current density, plating tungsten powder at 20-30h1 stirring frequency, has been obtained. Copper-coated tungsten powder composite powder can be prepared. The average thickness of the coating is about 2.5 m, the copper content can reach 54.3 wts. the preparation efficiency of the W-Cu composite powder is greatly improved. 2. The copper ion deposits in the place of low energy on the surface of tungsten powder and then grows continuously. The results of edX and XRD show that there is no impurity in the composite powder, and the copper coating on the surface exists in the form of crystal. The coating is thicker and the coating is intact. 3. The appropriate current density and stirring frequency can effectively control copper electroplating on the powder, and the appropriate stirring frequency can avoid the agglomeration of tungsten powder in the electroplating process. Breaking and redispersing the electroplated tungsten powder can cause the inner layer powder and the surface powder to change, transform, and ensure the uniformity of the powder plating. 4. The nucleation of copper follows the instantaneous nucleation mechanism under large superelectromotive force, and the deposition potential is more negative. The nucleation of copper shifts to the instantaneous nucleation curve. Under the condition of high current density, copper has high nucleation density, which is conducive to the formation of uniform and dense copper coating on tungsten powder with large specific surface area. 5. The role of organic additives in electrolyte was studied. Proper amount of polyethylene glycol can effectively increase the cathode polarization, increase the electrochemical reaction resistance, increase the polarization superpotential, and reduce the nucleation size of copper electrocrystallization. 6. Copper coated tungsten powder can improve the microstructure uniformity and decrease the porosity of tungsten copper composite. The copper matrix forms a continuous three-dimensional conductive network structure, and the tungsten particles become more dispersive, which enhances the interfacial adhesion between copper and tungsten. The density, hardness, thermal conductivity and thermal expansion coefficient of tungsten and copper composites were improved significantly, and the properties of tungsten and copper composites were improved significantly.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TB331;TB44

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