【正文】 洛陽理工學(xué)院畢業(yè)論文 24 外文資料翻譯 Characteristics and Problem of Chromecontaining Refractory* Akira YAMAGUCHI Okayama Ceramics Research Foundation, Nishikatakami 140618,Bizen,Okayama,7050021 Japan Abstract One of characteristics of Cr2O3containingrefractory is excellent corrosion resistance. However, here is a problem of hexavalent chromium, which is noxious to the human body, and easily formed by there actions among the refractory and CaO,Na2O and/orK2O in slag. In this article, the reason why the Cr2O3containingrefractory has excellent corrosion resistance, the forming conditions of hexavalent pounds ,and the methods for suppressing generation of the pound, are described as a base of further development of excellent refractories. Key words: Chromecontaining refractory,Cr2O3,CaCr2O4,CaCrO4,Corrosion resistance, Hexavalent chromium pound 1 IntroductionSiO2,ZrO2,Al2O3,Cr2O3,MgO and CaO are main high temperature oxides which constitute the refractories. In these oxides,Cr2O3 is the most excellent in corrosion resistance under the general service condition. However, there is a case that Cr2O3 contained in refractories changes to hexavalent chromium pounds by reacting with CaO,Na2O and/or K2O during service. The hexavalent chromium is known to be hazardous to human health. The health/environmental concerns have resulted in a significant reduction in the use of Cr2O3. In Japan, the gasification melting furnace has mainly been founded to deal with city dust and industrial waste recently. Since the refractories for this furnace are severely attacked by Na2O,K2O and/or CaO at 13001600℃ ,Cr2O3 containing refractories which have excellent corrosion resistance are used. However, the possibility of the use of the refractories throughout 洛陽理工學(xué)院畢業(yè)論文 25 future depends one stablishing safety system of chromium. This paper documents why Cr2O3 has excellent corrosion resistance, clarifies the forming conditions of hexavalent chromium pounds, and discusses the conditions and procedure for suppressing the for mation of hexavalent chromium pounds. 2 Characteristics of Chromium as A Refractory Component The Smallness of Dissolution Quantity to Slag Though phase equilibrium diagrams of 1to3ponent systems clarify the details of the phase patibility and reactions for the specified(1,2 or 3)ponents, they will not indicate the full details for actual service conditions where there usually are more than three ponents involved. Therefore, it is not possible to precisely determine the reactions between a refractory and each of wet liquid slag, iron/steel slag, cement, molten glass, etc., which are plex, multiponent system containing more than three ponents, based on a phase diagram. However, the reactions can be generally estimated using a pertinent threeponent (ternary)phase diagram of SiO2CaOhigh temperature oxide, because the main ponents in various slags are generally SiO2and CaO. When another ponent is added to three ponents, the melting temperature is declining and the formed liquid quantity is increasing. Therefore, it is necessary to examine the situation at temperatures which are higher than the actual practice. For simplification, three ponents are considered. In this example, the situation at 16001700℃ is examined. is the isothermal section of theCaOSiO2Cr2O3 equilibrium phase diagram[1]at 1600℃ .Maximum dissolution quantity of Cr2O3 to the slag with various CaO/SiO2 ratios, which is obtained from ,isshown in ,and the quantity at 1700℃ is also shown in quantity decreases with the decrease ofCaO/SiO2 in 洛陽理工學(xué)院畢業(yè)論文 26 slag. Isothermal section of CaOSiO2Cr2O3 equilibrium phase diagram at 1600℃ shows the saturation amounts of Cr2O3,Al2O3and MgO to the CaOSiO2 slag at 1600 ℃ ,which are estimated from the phase diagrams of CaOSiO2Cr2O3[1],CaOSiO2Al2O3[2]and CaOSiO2MgO[3]respectively. The saturation amount of Al2O3 is most for each slag. The saturation amount of Cr2O3 dissolved in the slag with 50/5030/70 of CaO/SiO2 ratio is less than that ofAl2O3 and MgO. Cr2O3 dissolution quantity is little, but knowledge on which is abounding. As an example, Fig. 4 shows the maximum dissolution quantity of MgAl1xCrxO4(MgAl2O4MgCr2O4 .)to CaMgSiO4 melt[1],which is obtained from the phase diagrams ofCaMgSiO4MgAl2xCrxO4[4].The quantity decreases with the increase of the MgCr2O4 amount in the solid solution. 洛陽理工學(xué)院畢業(yè)論文 27 Maximum dissolution quantity of Cr2O3 intoCaOSiO2 slag at 1600℃and 1700℃ Saturation amount of Cr2O3,Al2O3 and MgO to theCaOSiO2 slag at 1600℃ shows the contact surface of the refractories(75wt%Al2O325wt%Cr2O3)used for a waste melting gasifier .For the slag the saturation amount of Al2O3 is very large, and that of Cr2O3 is little, so Cr2O3 crystal precipitate and grow up. 洛陽理工學(xué)院畢業(yè)論文 28 Maximum dissolution quantity of MgAl1xCrxO4 intoCaMgSiO4 melt at 1600℃ Contact surface of the refractories (75wt%Al2O325wt%Cr2O3)used for a waste melting gasifier CorrosionResistant Improvement Effect by theCr2O3 Addition By adding Cr2O3 to other high temperature oxides, the melt generation temperature shouldn39。 （ 3）鎂碳磚在生產(chǎn)過程中易產(chǎn)生層裂、韌性差。爐子傾動(dòng)時(shí)受異常力的作用 渣 線 爐渣侵蝕 爐 底 受鋼水劇烈沖刷與磨損 頂?shù)讖?fù)合吹煉轉(zhuǎn)爐底供氣磚 受鋼水及爐渣化學(xué)侵蝕與劇烈沖刷 ,溫度驟變及氧化作用 出鋼口 受鋼水沖刷 ,爐渣侵蝕及溫度變化劇烈 洛陽理工學(xué)院畢業(yè)論文 17 第 4章 鎂碳磚技術(shù)發(fā)展趨勢(shì) 納米結(jié)構(gòu)基質(zhì)低碳鎂碳磚的開發(fā)研究 文獻(xiàn) [18， 19]通過采用納米尺度的炭黑以及復(fù)合石墨化炭黑改性酚醛樹脂 ，形成雜化樹脂 (HB:Hybrid Binder )和高性能雜化樹脂 (High Performance Hybrid Binder)。爐口、爐帽部位溫度變化劇烈，受渣蝕較嚴(yán)重，應(yīng)選用抗熱震性好，抗渣性強(qiáng)的鎂碳磚。通過調(diào)整施壓方法也可以提高氣體排出量，起到提高生產(chǎn)質(zhì)量的效果。 （ 2）、 控制配合料的濕度 洛陽理工學(xué)院畢業(yè)論文 鎂碳磚生產(chǎn)多采用壓制成型，與陶瓷墻地磚的產(chǎn)相似，對(duì)濕度要求較為嚴(yán)格。 熱處理 鎂碳磚不需高溫?zé)?，但需進(jìn)行熱處理。實(shí)踐表明，采用多級(jí)配比、選用合適的細(xì)粉粒度生產(chǎn)出的鎂碳磚具有較高的密度和強(qiáng)度，可以滿足使用要求。 其本身