本文選題：銅箔 + 雙層疊軋��； 參考：《北京科技大學》2015年博士論文

【摘要】：通過某些常規(guī)成形方法制備出具備晶粒尺寸多級多尺度結構或兩表面不同粗糙度結構的金屬材料,使其不同部位滿足不同使用工況的要求或具有不同的功能,是提高金屬材料綜合性能的一種有效途徑。已有研究表明,控制不同區(qū)域晶粒的變形程度呈梯度變化是獲得晶粒尺寸梯度結構的主要辦法,設計兩表面上的摩擦潤滑條件不同是獲得兩表面不同粗糙度結構的主要途徑。但迄今為止,未見有塑性加工方法直接制備同時具有梯度組織和兩表面不同粗糙度結構材料的相關報道。因此,本課題組提出了“采用雙層疊軋法直接制備兼具梯度組織和兩表面不同粗糙度結構材料”的思路,以期短流程、高效地開發(fā)出一種綜合性能優(yōu)異的金屬材料。而研究雙層疊軋材料的微觀組織和表面形貌特征,了解微觀組織和表面形貌的形成機理,弄清微觀組織和表面粗糙度的影響因素及規(guī)律,則是正確設計疊軋工藝,實現(xiàn)上述思路,制備出兼具梯度組織和兩表面不同粗糙度結構的高性能金屬材料的關鍵科學問題。 本論文以廣泛應用于電子領域的金屬純銅為對象,利用雙層疊軋成形純銅箔材,系統(tǒng)研究了雙層疊軋銅箔的微觀組織和表面形貌特征及形成機理,分析了微觀組織、表面形貌與疊軋銅箔性能之間的內(nèi)在聯(lián)系,所得結果為開發(fā)及應用兼具梯度組織和兩表面不同粗糙度結構的高性能純銅箔材奠定了實驗和理論基礎。研究工作主要取得了以下創(chuàng)新性結果： 開發(fā)了兼具厚度方向非對稱梯度組織和兩表面不同粗糙度結構的純銅箔材。以厚度50μm的雙層疊軋銅箔為例,其光面粗糙度Rz為0.061μm,毛面粗糙度Rz為1.095μm,滿足與撓性印刷電路板基板粘結時對銅箔表面粗糙度的要求,有望省略傳統(tǒng)銅箔生產(chǎn)工藝中的單面毛化處理；厚度方向上從光面至毛面,銅箔晶界間距平均值先由2.3μm增加至7.4μm,然后又降低到3.6μm；相比于相同壓下率的單層軋制銅箔,疊軋銅箔的耐彎折疲勞壽命提高15%以上。 揭示了雙層疊軋銅箔非對稱梯度組織及兩表面相異織構的形成機理。銅帶兩側不同的軋制壓應力和剪切應力,以及非對稱的變形滲透作用是影響不同區(qū)域晶粒尺寸、導致疊軋銅箔非對稱梯度組織形成的主要原因。光面?zhèn)鹊膹妷嚎s和剪切變形條件有利于促進晶粒向銅型織構取向集中,毛面?zhèn)鹊寞B合摩擦變形條件更有利于促進晶粒通過位錯滑移的方式向黃銅型織構取向集中,并且該作用強于機械孿生方式對晶粒向黃銅型織構取向轉動的促進作用。 基于金屬流動和變形力學理論,建立了雙層疊軋銅箔毛面粗糙度的形成模型,揭示了毛面的形成機理。由于金屬以沿軋制方向流動為主,在被閉合雙合油(或空氣)壓力的作用下,兩層疊合面之間的初始微坑首先發(fā)生沿軋制方向的連通合并,逐步形成穩(wěn)定的密閉微坑；隨著穩(wěn)定密閉微坑體積不斷壓縮、流體壓力不斷增大,微坑凹陷顯著變深；同時由于變形區(qū)內(nèi)金屬應力變形的特點,微坑更容易沿寬度方向連通合并,使得疊合面上的微坑發(fā)展成為具有一定寬度方向伸展的凹陷紋和凸起紋。 闡明了粗糙度與位錯密度對雙層疊軋銅箔表面功函數(shù)和耐蝕性能的共同影響作用。粗糙度主要影響疊軋銅箔表面功函數(shù)的均勻性,位錯密度增大對疊軋銅箔表面功函數(shù)降低的貢獻明顯大于表面粗糙度增大。對于厚度大于110μm的疊軋銅箔,兩表面的功函數(shù)都在4.4eV以上,此時耐蝕性能主要受粗糙度影響,光面耐蝕性能優(yōu)于毛面；對于厚度小于70μm的疊軋銅箔,兩表面的功函數(shù)都在4.1eV以下且均發(fā)生晶間腐蝕,此時耐蝕性能主要受位錯密度影響,毛面耐蝕性能優(yōu)于光面。 發(fā)現(xiàn)了雙層疊軋銅材拉伸斷裂的厚度效應。隨著厚度的減小,疊軋銅材表面硬化層所占厚度比例增大,芯部韌性層對延續(xù)銅材整體拉伸變形的作用不斷減弱,因而斷口中韌窩和韌窩凹坑數(shù)量和尺寸都明顯減少,斷后伸長率顯著降低。
[Abstract]:It is an effective way to improve the comprehensive performance of metal materials by using some conventional forming methods to prepare metal materials with multilevel multi-scale structure of grain size or different roughness structure of two surface, so that different parts meet the requirements of different operating conditions or have different functions. The main way to obtain grain size gradient structure is that the degree of grain deformation is gradient, and the main way to obtain the different roughness on the surface of the two surface is the main way to obtain the different roughness structure on the two surface. But so far, no plastic processing method has been produced directly with the gradient and two surface different roughness structure. As a result, we put forward the idea of using double layer rolling method to direct the preparation of structure materials with gradient and two surface roughness, in order to develop a kind of metal material with excellent comprehensive performance in a short process. The formation mechanism of microstructures and surface morphology and the understanding of the influencing factors and rules of the microstructure and surface roughness are the key scientific problems in the correct design of the rolling process and the realization of the above ideas, and the preparation of high performance metal materials with both gradient and two surface roughness structures.
In this paper, the microstructure and surface morphology characteristics and formation mechanism of double folded rolled copper foil are systematically studied by using the pure copper foil which is widely used in the field of electron. The internal relations between the microstructure, the surface morphology and the properties of the rolled copper foil are analyzed. The results are both for development and application. The experimental and theoretical basis of the high performance pure copper foil with the gradient structure and the two surface roughness structure has been established, and the following innovative results have been obtained.
The pure copper foil with the thickness direction asymmetric gradient and the two surface roughness structure is developed. With the thickness of 50 m thickness double layer rolled copper foil, the surface roughness Rz is 0.061 mu m and the surface roughness Rz is 1.095 mu m. It is expected to meet the requirements of the surface roughness of the copper foil when bonded to the flexible printed circuit board substrate. It is hopeful to save the tradition. In the production process of copper foil, the average value of the grain boundary between the copper foil and the surface of the copper foil is increased from 2.3 mu m to 7.4 u m in the direction of thickness, and then to 3.6 mu m, and the bending fatigue life of the rolled copper foil is increased by more than 15% compared to the single rolled copper foil with the same pressing rate.
The formation mechanism of asymmetric gradient and two surface texture of double folded rolled copper foil is revealed. The different rolling compressive stress and shear stress on both sides of the copper strip and asymmetric deformation permeability are the main reasons that affect the grain size of different regions and lead to the formation of asymmetrical gradient of the rolled copper foil. The shear deformation conditions are beneficial to promote the orientation of the grain to copper texture orientation, and the overlapping friction deformation conditions on the surface side of the wool side are more conducive to promoting the orientation of the brass texture orientation through dislocation slip, which is stronger than the mechanism of mechanical twins to promote the direction of the brass texture.
Based on the theory of metal flow and deformation mechanics, the formation model of the coat roughness of double folded rolled copper foil was established, and the formation mechanism of the wool surface was revealed. The initial micro pit between the two laminates was first connected along the rolling direction, as the metal was mainly flowing along the rolling direction and under the action of closed double oil (or air) pressure. At the same time, stable closed micro pits are gradually formed. With the steady compression of the stable closed micro pits, the pressure of the fluid is increasing, and the micro pits sag is greatly deepened. At the same time, the micro pits are more easily connected along the width direction because of the metal stress and deformation in the deformation zone, which makes the micro pits on the overlapped surface develop into a certain width direction. The depressions and protruding lines.
The effect of roughness and dislocation density on the surface work function and corrosion resistance of double rolled copper foil has been clarified. The roughness mainly affects the uniformity of the surface work function of the rolled copper foil. The contribution of dislocation density to the decrease of the work function of the surface of the rolled copper foil is obviously greater than that of the surface roughness. For the stacked rolling, the thickness is more than 110 mu. For copper foil, the work function of the two surface is above 4.4eV, and the corrosion resistance is mainly influenced by the roughness at this time, and the corrosion resistance of the surface is better than that of the wool surface. For the rolled copper foil with thickness less than 70 mu, the work function of the two surface is below 4.1eV and the intergranular corrosion occurs, and the corrosion resistance is mainly affected by the dislocation density, and the corrosion resistance performance of the wool surface is superior to the light. Noodles.
The thickness effect of the tensile fracture of the double layer rolled copper material was found. With the decrease of thickness, the thickness ratio of the hardened layer on the surface of the rolled copper increased, and the effect of the ductile layer on the whole tensile deformation of the copper material continued to decrease, so the number and the scale of the dimple and dimple pit in the fracture decreased obviously, and the elongation at the end of the fracture decreased significantly.
【學位授予單位】：北京科技大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TG335.58

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