熔铝炉用铝硅质耐火浇注料的性能研究

发布时间：2018-01-23 12:12

本文关键词： Al_2O_3-SiO_2 质浇注料铝合金熔炼炉侵蚀添加剂　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：我国汽车工业近年来发展迅速,今后的几十年仍将成为我国现代制造业的支柱产业之一,为降低能耗、提高质量、减轻自重,高性能铝合金在汽车上的应用越来越多,铝合金冶炼条件也越来越苛刻,而目前国内对熔铝炉用耐火材料的研究比较少。论文以Al_2O_3含量为85%(样号M85)和75%(样号M75)的矾土熟料、Al_2O_3含量为60%(样号M60)和45%(样号M45)的蓝晶石基莫来石为主要原料,加入α-Al_2O_3微粉、二氧化硅微粉、Secar71水泥作为结合系统,制备了超低水泥结合的浇注料标准试样和抗渣坩埚试样,研究了不同Al_2O_3含量的铝硅系原料对熔铝炉用浇注料性能的影响。在此基础上,选用综合性能优异的原料作为主原料,进而研究了K_2CO_3、BaSO_4、H_3BO_3等添加剂和铝溶胶结合剂对浇注料性能的影响。通过检测试样的常温和高温性能、采用坩埚法研究试样抗6063#铝合金的侵蚀性能、以及对试样进行物相组成和显微结构的分析,得出以下实验结果:研究Al_2O_3含量对浇注料性能影响的结果表明:试样在1200℃处理后显气孔率减小,表明试样有一定程度的烧结。M75试样由于物相接近纯莫来石的组成而难以烧结,导致抗折和耐压强度最小,M45试样抗折强度最高(18.2MPa),M85试样耐压强度最高(103.4MPa)。随着Al_2O_3含量的增加,试样的导热系数增大,如M85试样导热系数最大,M60试样由于气孔率最大导致导热系数最小。试样850℃下的热态抗折强度比常温抗折强度提高3-6MPa,最致密的M45试样热态抗折强度最高(22MPa),体现了在此温度下浇注料中微粉促进烧结的作用。铝合金液在850℃时与耐火材料中的SiO_2反应生成Al_2O_3和Si,伴随体积收缩,易造成耐火材料开裂损毁。Al_2O_3含量越高、气孔率越低的试样抗渗透和抗侵蚀性能越好,如M85试样。经850℃×72h侵蚀实验后,坩埚试样的侵蚀部分变为黑色,反应层中颗粒和基质均被侵蚀,侵蚀层中气孔被填充变得更加致密,材料结构发生变化,变质层与原砖层之间的热膨胀系数变得不一致,在间歇式工况条件下,容易出现层状结构剥落。同时,在侵蚀过程中,铝合金液中的Zn元素蒸汽从合金中逸出,在过渡层富集。浇注料中加入K_2CO_3添加剂后,采用柠檬酸钠和FS20作减水剂时,试样的流动性最好。高温下K_2CO_3易与金属Al和O_2反应生成KAlO_2和CO_2,使材料的抗侵蚀性能降低。采用铝溶胶作结合剂,加入量较低时试样抗侵蚀性能略有增加,随着加入量的增加,浇注料流动性变差,显气孔率增加,抗侵蚀性能下降。随着BaSO_4加入量的增加,试样的显气孔率增大、导热系数减小、体积密度减小、常温和热态强度降低。900℃时BaSO_4与试样中的Al_2O_3和SiO_2反应生成钡长石(BaAl2Si2O8)和富含钡的液相,降低了基质中SiO_2和莫来石的含量,材料的抗侵蚀性能明显提高。未加入BaSO_4时坩埚试样的侵蚀率为5.10%,加入1.0%BaSO_4后坩埚试样的侵蚀率降低到3.75%,BaSO_4加入量≥2%时,坩埚试样均无肉眼可见侵蚀。但当BaSO_4加入量2%,高温下生成富含钡的液相较多,试样的常温和热态强度降低。BaSO_4加入量较少时,材料的抗侵蚀性能得不到提高,实验得出,BaSO_4最佳加入量为2%。随着H_3BO_3加入量的增加,浇注料试样逐渐变黄,H_3BO_3加入量为2%时,试样已经变为土黄色,表面有宽约0.5mm的裂纹,导致试样显气孔率增大、强度下降。适量H_3BO_3加入后,坩埚试样的抗侵蚀性能明显增强,H_3BO_3加入量为0.1%和0.2%时,经850℃×72h侵蚀实验后,坩埚试样无肉眼可见侵蚀。通过SEM照片可见,1200℃处理后试样中的刚玉成颗粒状,B2O3与Al_2O_3反应生成液相和一致熔融化合物9Al_2O_3·2B2O3,促进烧结,B1和B2试样中刚玉颗粒间的孔隙被玻璃相填充并连接在一起。H_3BO_3加入量较小(0.05%)时,材料的抗侵蚀性能较差;H_3BO_3加入量较大(0.2%)时试样高温下(1200℃)产生裂纹,影响材料的强度。结果显示,H_3BO_3最佳加入量为0.1%,最佳处理温度为900℃。
[Abstract]:China's automobile industry developed rapidly in recent years, the coming decades will become one of the pillar industries in China's modern manufacturing industry, in order to reduce energy consumption, improve quality, reduce weight, high performance Aluminum Alloy used more and more in the car, Aluminum Alloy smelting conditions are more harsh, and the current domestic for aluminum melting study on furnace refractory is less. The content of Al_2O_3 is 85% (sample No. M85) and 75% (sample No. M75) of bauxite, the content of Al_2O_3 is 60% (sample No. M60) and 45% (sample No. M45) of Kyanite based mullite as main raw material, adding a -Al_2O_3 powder, silica powder Secar71, as a combination of cement system, standard castable samples ultra low cement bonded slag and crucible samples were prepared and studied the effect of Al Si material with different Al_2O_3 content on the properties of material casting for aluminum melting furnace. On this basis, with excellent comprehensive properties of raw materials As the main raw material, BaSO_4 of K_2CO_3, H_3BO_3, effects of additives and aluminum sol binder on properties of the castables. By detecting the samples at room temperature and high temperature performance, corrosion resistance by crucible test specimens of anti 6063# Aluminum Alloy, and analysis of samples the phase composition and microstructure, the results were as follows Al_2O_3: research content of material properties of the casting results showed that the samples in 1200 treatment after the porosity decreases, which shows that the sample has a certain degree of sintered.M75 samples due to phase close to pure mullite composition to lead sintering, the flexural strength and compression strength is the smallest, the highest flexural strength of M45 specimens (18.2MPa). The highest compressive strength of M85 specimen (103.4MPa). With the increase of Al_2O_3 content, increase the coefficient of thermal conductivity of samples, such as M85 sample maximum thermal conductivity of M60 samples, due to the porosity in thermal conductivity Minimum. Hot sample at 850 DEG C than room temperature flexural strength flexural strength increased 3-6MPa, M45 were the most dense hot the highest flexural strength (22MPa), embodies the castable to promote sintering powder at this temperature. Aluminum Alloy liquid at 850 DEG C and refractory materials in SiO_2 reaction formation of Al_2O_3 and Si, with volume shrinkage, easy to cause the refractory cracking damage to the content of.Al_2O_3 is higher, the lower the porosity of sample permeability and anti erosion performance better, such as M85 samples. By 850 DEG C * 72h erosion experiment, erosion into black crucible samples, the reaction layer particles and matrix are erosion, erosion layer filled pores become more compact, material structure change, expansion coefficient between the metamorphic layer and the original brick layer heat become inconsistent in batch conditions, prone to layered peeling. At the same time, in the process of erosion, Aluminum Alloy The Zn element in the liquid vapor escaping from the alloy, in the transition layer. Enrichment of K_2CO_3 additive castable, using sodium citrate as reducing agent and FS20, the fluidity is best. K_2CO_3 is easy and high temperature metal Al and O_2 reaction of KAlO_2 and CO_2, the anti erosion properties of materials decreased using aluminum sol as binder, adding amount of low sample anti erosion properties increased slightly with the increase of addition amount, flowability variation, porosity increased, corrosion resistance decreased. With the increasing amount of BaSO_4, the apparent porosity of sample rate increases, the thermal conductivity decreases, the bulk density decreases cold and hot strength, reduce Al_2O_3 and SiO_2 reaction of barium feldspar BaSO_4 in the specimen with.900 C (BaAl2Si2O8) and barium rich liquid phase, reduce the content of SiO_2 in matrix and mullite materials, the anti erosion properties improved significantly. Without B ASO_4 when the sample rate is 5.10% crucible erosion, erosion after joining the 1.0%BaSO_4 crucible sample rate reduced to 3.75%, the addition amount of BaSO_4 was higher than 2%, the crucible samples without visible erosion. But when the amount of BaSO_4 2% generation high temperature barium rich liquid at room temperature and more, decrease the thermal strength of.BaSO_4 added a small quantity of material, the anti erosion ability is not improved, the best amount is BaSO_4 2%. with the increasing amount of H_3BO_3 castable samples changed yellow, H_3BO_3 content is 2%, the sample has become yellow, the surface crack width of 0.5mm, resulting in the sample porosity the amount of H_3BO_3 increases, strength decreased. After adding the anti erosion properties of crucible samples significantly enhanced, H_3BO_3 content is 0.1% and 0.2%, by 850 DEG C * 72h erosion experiment, the crucible samples without visible erosion. SEM images of the visible, at 1200 DEG C After the sample was Yucheng granular, B2O3 and Al_2O_3 reaction liquid and congruent melting compounds 9Al_2O_3 2B2O3, promote sintering and pore corundum particles between the B1 and B2 samples were filled with glass phase and tie together the amount of.H_3BO_3 is small (0.05%), the anti erosion properties of materials is poor; the large amount of H_3BO_3 added (0.2%) when the sample under high temperature (1200 DEG C) crack, affect the strength of the material. The results showed that the optimum amount of H_3BO_3 was 0.1%, the optimum processing temperature is 900 degrees centigrade.

【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG232;TQ175.732

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