本文關(guān)鍵詞： 碳化硅陶瓷 二維流場仿真 三維電場仿真 研拋 摩擦磨損特性　出處：《哈爾濱工業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：碳化硅具有優(yōu)良的物理化學(xué)性能,是制備空間大尺寸輕型反射鏡的新材料。但碳化硅具有硬度高、脆性大、對缺陷敏感等特點,難以獲得高表面質(zhì)量和高效加工。傳統(tǒng)加工方法以及化學(xué)機(jī)械拋光(CMP)因磨粒的存在易產(chǎn)生表面及亞表面損傷,摩擦化學(xué)研拋(TCP)不采用磨料,可獲得高精度碳化硅表面,但效率低。摩擦電化學(xué)研拋(TECP)可實現(xiàn)金屬表面高效、高精度加工,但對碳化硅陶瓷的摩擦電化學(xué)研拋機(jī)理尚不十分明確。論文通過對碳化硅陶瓷研拋的流場仿真和摩擦磨損實驗研究,獲得不同工藝條件對其研拋特性的影響規(guī)律,研究對實現(xiàn)碳化硅陶瓷的高效超精密加工具有重要的理論和指導(dǎo)意義。首先針對帶孔拋光墊,利用Fluent軟件建立研拋過程的二維有限元模型,并研究了研拋速度、拋光墊厚度、小孔尺寸及流體膜厚度對流體流場特征的影響規(guī)律。利用Ansoft Maxwell軟件建立研拋副間電場分布的三維有限元模型,并研究了拋光墊電導(dǎo)率和厚度對電場分布的影響規(guī)律。然后,對原有的行星輪式圓平動研拋試驗機(jī)進(jìn)行結(jié)構(gòu)改進(jìn),實現(xiàn)了載荷和電壓的加載;開發(fā)了數(shù)據(jù)采集處理系統(tǒng),實現(xiàn)了壓力、摩擦力和摩擦系數(shù)的在線監(jiān)測。最后,應(yīng)用改進(jìn)的試驗機(jī)研拋碳化硅陶瓷,獲得了不同外加電壓、研拋液及研拋配副對其摩擦磨損性能的影響規(guī)律。仿真研究表明:帶孔拋光墊的小孔直徑和數(shù)量對流體的承載能力和摩擦力有重要影響。當(dāng)拋光墊上小孔的數(shù)量一定時,隨著小孔直徑的增大,承載能力和摩擦力降低;當(dāng)小孔間距和小孔直徑的比值一定時,隨著小孔數(shù)量的增多,承載能力先降低后增加,摩擦力降低。碳化硅上的外加電壓對研拋液及拋光墊的影響范圍和作用較小。增加拋光墊電導(dǎo)率、降低拋光墊厚度可提高研拋表面的電流密度。實驗研究表明:碳化硅與鑄鐵盤配對研磨時,3%Na OH的研拋效率略高于去離子水的;對試件不加電或施加正電時的研磨效率是施加負(fù)電時的3倍左右。與砂紙配對研磨時,砂紙粒度越大,摩擦系數(shù)越大,機(jī)械去除作用越強(qiáng),因而研磨效率越高。在與細(xì)砂紙研磨時,因其機(jī)械去除作用減弱,3%Na OH的化學(xué)去除作用,特別是電化學(xué)去除作用較為明顯。此時,對試件施加正電的研磨效率是施加負(fù)電和不加電的1.5倍左右。不同加電狀態(tài)下碳化硅與磨砂革配對拋光時,摩擦系數(shù)相近,但加正電時的拋光效率是負(fù)電和不加電時的8~10倍,電化學(xué)去除作用明顯提高;打孔磨砂革因表面平整度差,拋光時比不帶孔磨砂革的摩擦系數(shù)大、波動劇烈;不同拋光液性能影響實驗表明,W5金剛石懸浮液拋光效率遠(yuǎn)高于3%Na OH溶液的,兩者混合液的拋光效率介于其間。
[Abstract]:Silicon carbide has excellent physical and chemical properties and is a new material for the preparation of light mirror with large space size. However, silicon carbide has the characteristics of high hardness, high brittleness, sensitivity to defects, etc. It is difficult to obtain high surface quality and high efficiency machining. Traditional processing methods and chemical mechanical polishing (CMP) can easily cause surface and subsurface damage due to the existence of abrasive particles. Friction chemical polishing and polishing (TCPP) can obtain high precision silicon carbide surfaces without abrasive materials. But the efficiency is low. The friction electrochemical polishing and polishing (TECP) can realize the high efficiency and high precision machining of metal surface. However, the friction and electrochemical polishing mechanism of sic ceramics is not very clear. Through the flow field simulation and friction and wear experiments of sic ceramics polishing, the effects of different technological conditions on the polishing characteristics of sic ceramics are obtained. The research has important theoretical and guiding significance for the realization of high-efficiency ultra-precision machining of silicon carbide ceramics. Firstly, a two-dimensional finite element model of polishing process is established with Fluent software, and the polishing speed and the thickness of polishing pad are studied. The effect of pore size and film thickness on the flow field characteristics is studied. A three-dimensional finite element model of electric field distribution between polishing and polishing pairs is established by using Ansoft Maxwell software, and the influence of the electric conductivity and thickness of polishing pad on the electric field distribution is studied. By improving the structure of the original planetary wheel type circular flattening machine, the loading of load and voltage is realized, the data acquisition and processing system is developed, and the on-line monitoring of pressure, friction and friction coefficient is realized. The application of the improved testing machine to polishing silicon carbide ceramics has obtained different applied voltages. Simulation results show that the diameter and number of holes with holes have an important effect on the bearing capacity and friction force of the fluid. When the number of holes on the polishing pad is constant, With the increase of pore diameter, the bearing capacity and friction force decrease, when the ratio of pore spacing to orifice diameter is constant, with the increase of the number of holes, the bearing capacity decreases first and then increases. The effect of applied voltage on silicon carbide on polishing liquid and polishing pad is small. The electric conductivity of polishing pad is increased. Reducing the thickness of polishing pad can increase the current density of polishing surface. The experimental results show that the polishing efficiency of 3NaOH is slightly higher than that of deionized water when sic and cast iron disk are paired and ground. The grinding efficiency of the specimen without or with positive charge is about three times higher than that with negative charge. The larger the grain size of sand paper is, the greater the friction coefficient is, and the stronger the mechanical removal is when the sand paper is paired with sand paper. Therefore, the higher the grinding efficiency is, the more obvious is the chemical removal of NaOH, especially the electrochemical removal, due to its mechanical removal. The grinding efficiency of positive charge is about 1.5 times higher than that of negative charge and no charge. The friction coefficient of silicon carbide and polished leather is similar in different states, but the polishing efficiency of positive charge is 810 times higher than that of negative charge and no charge. The effect of electrochemical removal was obviously improved, and the friction coefficient of perforated abrasive leather was larger and fluctuated sharply than that of non-hole polished leather during polishing because of the poor surface smoothness. The results show that the polishing efficiency of W5 diamond suspension is much higher than that of 3NaOH solution, and the polishing efficiency of the mixture is between them.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ174.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 李劍鋒,黃靜琪,譚壽洪,陳忠明,丁傳賢;增韌SiC陶瓷在蒸餾水潤滑下的摩擦學(xué)特性[J];硅酸鹽學(xué)報;1998年03期

2 王金虎;翟文杰;;電勢對硅片摩擦電化學(xué)材料去除特性的影響[J];哈爾濱工業(yè)大學(xué)學(xué)報;2014年07期

3 雒建斌;李津津;;摩擦學(xué)的進(jìn)展和未來[J];潤滑與密封;2010年12期

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本文編號：1508358