本文選題：鋁熱還原-電磁鑄造 + 銅鉻合金��； 參考：《東北大學(xué)》2011年碩士論文

【摘要】：CuCr合金可以廣泛應(yīng)用于集成電路的引線框、各種電極、電觸頭、高強(qiáng)度導(dǎo)線等要求高導(dǎo)電性、高強(qiáng)度的領(lǐng)域,是一種具有廣泛應(yīng)用前景的大功率、高壓觸頭材料。傳統(tǒng)的粉末冶金法、熔滲法以及真空電弧熔煉法制備CuCr都存在著生產(chǎn)成本高,工藝復(fù)雜,成品率低等缺陷,尤其是在制備大尺寸合金鑄錠方面存在困難。針對這一現(xiàn)象,課題組提出基于鋁熱還原電渣重熔法制備銅鉻合金的新工藝,先后獲得相關(guān)發(fā)明專利2項(xiàng)。前期研究表明：鋁熱還原-電磁鑄造法直接制備的銅鉻合金中存在氣孔以及氧化物夾雜等缺陷,本文將對鋁熱-電磁鑄造法制備的合金中夾雜物賦存形態(tài)、分布規(guī)律以及氣孔等微觀缺陷進(jìn)行系統(tǒng)分析,為電渣精煉工藝選擇提供理論依據(jù)。 首先,通過熱力學(xué)計(jì)算得出鋁熱反應(yīng)在不同溫度下的△Gθ、△G和△H值,確定最高反應(yīng)溫度及熱效應(yīng)。計(jì)算結(jié)果表明,體系反應(yīng)的絕熱溫度為2848K,而且反應(yīng)的吉布斯自由能變很負(fù),故而以鋁作還原劑在理論上是可行的。采用差熱分析研究了CuO-Cr2O3-A1體系的動(dòng)力學(xué),結(jié)果表明：反應(yīng)表觀活化能Ea=151.272kJ/mol,反應(yīng)級(jí)數(shù)n=2.48,反應(yīng)動(dòng)力學(xué)方程為：da/dT=0.2464×105e-151272/RT(1-α)2.48。 其次,采用SEM、能譜分析技術(shù)及金相顯微鏡對合金進(jìn)行了表征,分析了在不同工藝條件下制備的合金中夾雜物賦存狀態(tài)及微觀結(jié)構(gòu)缺陷。結(jié)果表明：合金中存在富銅區(qū)、富鉻區(qū)以及夾雜物區(qū)三個(gè)明顯的區(qū)域,夾雜物主要以氣孔和A1203相形式存在,多分布在富銅相區(qū)以及富銅相與富鉻相界面處。 然后,采用XRD技術(shù)對熔煉渣及合金相組成進(jìn)行表征。結(jié)果表明：熔煉渣主要由A1203相以及少量的金屬Cr相組成,合金主要有Cu相、Cr相和少量A1203夾雜相組成。 最后,采用金相顯微鏡及image圖像處理技術(shù)對合金中氣孔及夾雜物分布規(guī)律進(jìn)行了系統(tǒng)研究。結(jié)果表明：電磁攪拌和強(qiáng)化水冷均能減少氣孔率。其中,水冷強(qiáng)度加強(qiáng)后合金中的氣孔能減少18%,采用銅模澆鑄可使Cr粒子細(xì)化,添加適量的Na3A1F6、CaF2、CaO、發(fā)熱劑均能有效地減少合金中夾雜物含量。
[Abstract]:CuCr alloy can be widely used in the field of lead frame, various electrodes, electrical contacts, high strength conductors and so on. CuCr alloy is a kind of high power and high voltage contact material with wide application prospect. The traditional methods of powder metallurgy, infiltration and vacuum arc melting have many disadvantages, such as high production cost, complex process, low yield, etc. Especially, it is difficult to prepare large size alloy ingot. In view of this phenomenon, a new process for the preparation of copper-chromium alloy based on aluminothermic reduction electroslag remelting method was put forward, and two patents were obtained. Previous studies show that there are defects such as porosity and oxide inclusions in the Cu-Cr alloy prepared directly by aluminothermic reduction-electromagnetic casting. In this paper, the inclusions in the alloy prepared by aluminothermic-electromagnetic casting are studied. The distribution law and microcosmic defects such as porosity were systematically analyzed, which provided the theoretical basis for the selection of electroslag refining process. Firstly, the G 胃, G and H values of the thermal-thermal reaction at different temperatures are obtained by thermodynamic calculation, and the maximum reaction temperature and thermal effect are determined. The calculated results show that the adiabatic temperature of the reaction is 2848Kand the Gibbs free energy of the reaction becomes very negative, so it is theoretically feasible to use aluminum as the reductant. The kinetics of CuO-Cr2O3-A1 system was studied by differential thermal analysis. The results showed that the apparent activation energy of the reaction was 151.272 kJ / mol, the reaction order was nu 2.48, and the kinetic equation of the reaction was: 0. 2464 脳 105e-151272 / RT1-偽 2.48. Secondly, the alloy was characterized by means of SEM, EDS and metallographic microscope. The existing state of inclusions and microstructure defects in the alloys prepared under different technological conditions were analyzed. The results show that there are three obvious regions in the alloy, such as copper-rich zone, chromium-rich zone and inclusion zone. The inclusions mainly exist in the form of porosity and A1203 phase, and are mainly distributed in the copper-rich phase region and the interface between copper-rich phase and chromium-rich phase. Then, XRD technique was used to characterize the composition of slag and alloy. The results show that the slag mainly consists of A1203 phase and a small amount of metallic Cr phase, and the alloy mainly consists of Cu phase Cr phase and a small amount of A1203 inclusion phase. Finally, the distribution of pores and inclusions in the alloy was systematically studied by metallographic microscope and image processing technology. The results show that both electromagnetic stirring and enhanced water cooling can reduce the porosity. The porosity in the alloy can be reduced by 18% after the strengthening of water cooling strength. The Cr particles can be refined by copper mold casting. Adding appropriate amount of Na _ 3A _ 1F _ 6 and CaF _ 2 Cao can effectively reduce the content of inclusions in the alloy by adding appropriate amount of Na _ 3A _ 1F _ 6 and CaF _ 2CaO.
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2011
【分類號(hào)】：TG291

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本文編號(hào)：2040049