镁铝尖晶石对方镁石-复合尖晶石砖性能及抗V2O5侵蚀性的影响

以高纯镁砂、高铁镁砂、铁铝尖晶石砂、镁铝尖晶石为原料,于1600℃烧成制备了方镁石-复合尖晶石试样,研究不同镁铝尖晶石对试样性能的影响,采用SEM观察和分析了V2O5气氛侵蚀后试样的微观形貌。结果表明：添加75MA和90MA的试样,显气孔率随着尖晶石含量的增加先增加后降低;添加66MA的试样,显气孔率随着尖晶石含量增加而增加;添加三种尖晶石的试样,耐压强度、高温抗折强度均随着尖晶石含量增加而降低;添加12%75MA和90MA试样的热震稳定性好于添加66MA的试样;添加90MA的试样,尖晶石含量越高,试样的抗侵蚀性越好;添加66MA尖晶石的试样,尖晶石含量越高,试样的抗侵蚀性越差;当试样中MA含量相同时,Al2O3含量越高,试样的抗V2O5侵蚀性越好。     

添加剂对方镁石——尖晶石砖性能影响

以电熔氧化镁、电熔镁铝尖晶石为主要原料 ,分别加入TiO2 、Al2 O3、Fe2 O3、CaO添加剂予以改性 ,通过高温烧结制成方镁石—尖晶石试样 ,研究其物理性能。结果表明 :添加一定量的TiO2 对方镁石—尖晶石的物理性能有大幅度的改善 ;随着Al2 O3、Fe2 O3、CaO加入量的增加试样的常温抗压强度及体积密度有所提高 ;XRD分析证明试样基质主晶相为MgO ,次晶相为尖晶石 ;SEM分析可看到基质与颗粒间反应层较薄 ,结合不紧密 ,硅酸盐相表面有少量脱溶相     

成型受压方向对方镁石-尖晶石-碳砖性能的影响

研究了成型受压方向对方镁石 尖晶石 碳砖热膨胀率、抗渣等性能的影响 ,实验研究结果表明 :平行受压方向上的热膨胀率大于垂直受压方向上的热膨胀率 ,平行受压方向上的抗渣性优于垂直受压方向上的抗渣性 ,并从显微镜观察到了含石墨耐火砖石墨的趋向分布情况     

电熔合成镁铝尖晶石及其应用研究

作者利用浮选菱镁矿和工业氧化铝电熔合成了镁铝尖晶石;利用电熔尖晶石和高纯镁砂制成了高耐火性能的方镁石-尖晶石砖,利用电熔尖晶石、电熔镁砂和鳞片石墨制成了抗氧化性明显优于镁炭砖的尖晶石炭砖。     

添加剂ZrO_2对方镁石-铝镁尖晶石质耐火材料性能的影响

研制无铬耐火材料对水泥工业的环保发展有着重要意义.以电熔镁砂颗粒、镁砂细粉、铝镁尖晶石、α-Al_2O_3细粉作为主要成分,添加2%无定形态TiO_2细粉最为助烧结剂,以此组成耐火材料的基础配方,并考察了ZrO_2对该耐火材料性能的影响.结果表明:随着Zr O2用量的增加,试样显气孔率和体积密度呈增长趋势,但幅度不太明显;常温抗折强度、抗热震性能、抗渣性等都呈先增大后减小趋势,但达到最值的用量不同;荷重软化温度呈逐渐下降趋势;综合各项性能来看,ZrO_2的最佳用量为4%~6%.     

ZrO2对镁尖晶石耐火材料力学性能的影响

在方镁石－尖晶石系统中添加３种含锆氧化物，改变了材料的相组成及显微结构，提高了材料的中温强度和热震稳定性。     

利用煅烧镁铝尖晶石制造方镁石-尖晶石砖的研究

作者完成了利用煅烧镁铝尖晶石制造方镁石-尖晶石砖的工艺条件的实验室研究和工业试制。结果表明,采用天然原料(高铝矾土和菱镁矿)煅烧合成的镁铝尖晶石料和制砖镁砂,控制合理的工艺参数,可以制得抗热震性优良、高温性能良好的方镁石-尖晶石砖。文章中提出的合成镁铝尖晶石的配料公式简单、实用,适用于不同品位原料合成镁铝尖晶石的配料计算。     

利用镁铝尖晶石改善镁质滑板材料性能研究

本文着重探讨了煅烧镁铝尖晶石的品位、富含氧化镁数量、煅烧温度及其加入量对镁质滑板材料性能的影响,比较了镁铝尖晶石的加入形式与材料性能的关系。研究表明:在一定条件下,以煅烧镁铝尖晶石作为镁质滑板材料,达到了提高其抗热震性的目的;当采用中颗粒镁铝尖晶石代替煅烧镁铝尖晶石时,材料性能可与日本同类产品相比较。     

水泥窑用方镁石-铁铝尖晶石砖的性能研究

以电熔镁砂、铁粉、氧化铁粉和α-Al2O3粉为原料,制备方镁石-铁铝尖晶石砖,研究了烧结温度和铁加入量对方镁石-铁铝尖晶石砖性能的影响,采用XRD和SEM对试样的物相组成和显微结构进行了分析和表征.结果表明,提高烧结温度有利于方镁石-铁铝尖晶石砖性能的提高,1500℃烧成的试样最致密,综合性能较好,增大铁加入量不利于方镁石-铁铝尖晶石砖性能的提高.与直接结合镁铬砖相比,方镁石-铁铝尖晶石砖的常温耐压强度、抗折强度和热震稳定性较好,挂窑皮性和抗侵蚀性与其相近.     

免烧成硼酸铝-碳化硅耐火材料的性能

以碳化硅为主要原料,分别以酚醛树脂、氧化铝和氧化硼粉体作为常温和高温结合剂,研究了免烧成硼酸铝-碳化硅耐火材料的体积密度、抗折强度和抗热震性.结果表明:当酚醛树脂的质量分数为5%时,耐火材料的体积密度和抗折强度分别为266g·cm-3和13~21MPa;在960℃烧结之后,主要物相为SiC,Al2O3,Al4B2O9;当高温结合剂的质量分数为75%时材料的体积密度最大,为255g·cm-3;当高温结合剂的质量分数为125%时,材料的抗折强度最大,为19MPa;经过5次高温热震后,高温结合剂的质量分数为75%时材料抗热震性较好,强度损失率为25%.     

Reduction in secondary dendrite arm spacing in cast eutectic Al-Si piston alloys by cerium addition

The effects of Ce on the secondary dendrite arm spacing (SDAS) and mechanical behavior of Al-Si-Cu-Mg alloys were investigated. The reduction of SDAS at different Ce concentrations was evaluated in a directional solidification experiment via computer-aided cooling curve thermal analysis (CA CCTA). -The results showed that 0.1wt%-1.0wt% Ce addition resulted in a rapid solidification time, △T_S, and low solidification temperature, △T_S, whereas 0.1wt% Ce resulted in a fast solidification time, △ta-Al, of the α-Al phase. Furthermore, Ce addition refined the SDAS, which was reduced to approximately 36%. The mechanical properties of the alloys with and without Ce were investigated using tensile and hardness tests. The quality index (Q) and ultimate tensile strength of (UTS) Al-Si-Cu-Mg alloys significantly improved with the addition of 0.1wt% Ce. Moreover, the base alloy hardness was improved with increasing Ce concentration.     

Effect of graphite powder as a forming filler on the mechanical properties of SiCp/Al composites by pressure infiltration

(38vol% SiCp + 2vol% Al₂O_3f)/2024 Al composites were fabricated by pressure infiltration. Graphite powder was introduced as a forming filler in preform preparation, and the effects of the powder size on the microstructures and mechanical properties of the final composites were investigated. The results showed that the composite with 15 μm graphite powder as a forming filler had the maximum tensile strength of 506 MPa, maximum yield strength of 489 MPa, and maximum elongation of 1.2%, which decreased to 490 MPa, 430 MPa, and 0.4%, respectively, on increasing the graphite powder size from 15 to 60 μm. The composite with 60 μm graphite powder showed the highest elastic modulus, and the value decreased from 129 to 113 GPa on decreasing the graphite powder size from 60 to 15 μm. The differences between these properties are related to the different microstructures of the corresponding composites, which determine their failure modes.     

累托石与白泥在不烧高铝砖中的结合性对比研究

分别以累托石及白泥为结合剂、高铝矾土熟料为基础料制备不烧高铝砖,借助旋转流变仪、激光粒度仪、XRD及SEM等对不同球磨条件下累托石及白泥的性能与微观结构进行表征,对比分析了累托石及白泥在不烧高铝砖中的结合机理。结果表明,在110℃干燥24h后以及继续在750℃保温3h的热处理条件下,累托石结合不烧高铝砖的常温耐压强度均高于白泥结合不烧高铝砖的相应值。相比白泥,累托石粒径大、黏度高、泥浆稳定性好且具有不规则褶曲形貌的微米级片状结构都是其结合性能优于前者的主要原因。     

Al含量对AJC镁合金显微组织和力学性能的影响

以Mg-4Al-2Sr-1Ca合金为基体,在提高合金中Al含量的基础上,配制了不同成分的几种Mg-(4-7)Al-2Sr-1Ca合金.研究了Al含量对Mg-Al-Sr-Ca合金显微组织和力学性能的影响.研究发现,Mg-4Al-2Sr-1Ca合金的主要组成相为α-Mg,沿枝晶界分布的Mg2Ca α-Mg共晶相、Mg-Al-Sr三元相及晶内Al2Ca颗粒相.当Al元素质量分数增大到5%～6%时,合金中出现了(Mg,Al)2Ca相;进一步增大Al元素质量分数至7%,另一种新相Al4Sr相也被观察到.随着Al含量的增大,合金的强度和塑性在室温和高温下都有所上升.在175℃/70MPa和200℃/70MPa下,Mg-5Al-2Sr-1Ca和Mg-6Al-2Sr-1Ca合金表现出了比其他合金更好的高温抗蠕变性能.     

不同耐火原料的耐碱腐蚀性能分析

采用快速圆片试验法,对白刚玉、板状刚玉、红柱石、CaAl4O7/MgAl2O4(CA2/MA)复相材料、富铝镁铝尖晶石AR90和AR78试样进行热力学分析和显微结构观察,研究其耐碱腐蚀性能。结果表明,AR90、AR78和CA2/MA与碱盐反应后生成了少量的低密度钾β-Al2O3(K2O·11Al2O3)和KMg2Al15O25,所引起的体积膨胀较小,线变化率满足耐碱腐蚀标准;板状刚玉、白刚玉和红柱石与碱盐反应后生成了大量的低密度化合物K2O·11Al2O3和KAlSiO4,所引起的体积膨胀较大,线变化率不满足耐碱腐蚀标准。     

压力对A380铝合金的铸造组织和力学性能的影响

对A380铝合金进行了挤压铸造成型和传统重力铸造成型,并制得试样.采用偏光显微镜、扫描电镜、定量金相分析、拉伸性能测试等手段,研究在不同压力下挤压铸造A380铝合金的铸造组织和力学性能.结果表明:当压力在0~75MPa范围内时,随着压力的增加,一次枝晶臂尺寸和气孔率得到大幅下降,共晶组织体积分数增加;二次枝晶臂间距减小;针状富铁β-Al5FeSi相尺寸大幅度减小,同时有部分汉字状α-Al8(Fe,Mn)3Si2相生成.当压力在75~100MPa范围内时,压力继续增加对合金组织细化、第二相形貌改善和力学性能提高的作用不明显.挤压铸造试件与重力铸造试件相比,气孔率减小,显微组织细化,力学性能显著提高.当压力为75MPa时,挤压铸造A380铝合金的铸态抗拉强度和伸长率分别比重力铸造提高19%和65%.     

Effects of La addition on the microstructure and tensile properties of Al-Si-Cu-Mg casting alloys

The effects of La addition on the microstructure and tensile properties of B-refined and Sr-modified Al-11Si-1.5Cu-0.3Mg casting alloys were investigated. With a trace addition of La (0.05wt%-0.1wt%), the mutual poisoning effect between B and Sr can be neutralized by the formation of LaB₆ rather than SrB₆. By employing a La/B weight ratio of 2:1, uniform microstructures, which are characterized by well refined α-Al grains and adequately modified eutectic Si particles as well as the incorporation of precipitated strengthening intermetallics, are obtained and lead to appreciable tensile properties with an ultimate tensile strength of 270 MPa and elongation of 5.8%.     

Effect of pre-annealing treatment on the microstructure and mechanical properties of extruded Al-Zn-Mg-Cu alloy bars

Taking extruded Al-Zn-Mg-Cu alloy (7A04 alloy) bars as the research object, the effect and mechanism of pre-annealing treatments on the microstructure and mechanical properties of the aged alloy bars were investigated. The results show that a pre-annealing treatment at 350℃ for 15 h before a T6 treatment substantially reduced the sensitivity of the microstructure and mechanical properties of the extruded 7A04 aluminum alloy specimens toward the extrusion temperature. The average grain sizes of the specimens extruded at 390 and 430℃ after T6 treatment were 3.4 and 8.1 μm, respectively, and their elongations to failure were 7.0% and 9.2%, respectively. However, after pre-annealing + T6 treatment, the differences in both the grain sizes and the elongations of the specimens became small, i.e., their average grain sizes were 3.2 and 3.8 μm and their elongations were 12.0% and 13.3%, respectively. For the specimens extruded at the same temperature, pre-annealing treatment obviously improved the plasticity of the alloy, which is attributed to an increase in soft texture or to grain refinement in the specimens as a result of the pre-annealing + T6 treatment.     

Effect of Silicon Content on Wear Resistance of Al - Si Alloys

The sliding wear behavior of hypoeutectic, eutectic and hypereutectic Al - Si alloys under lubricating condition was investigated. The wear mechanism of three kinds of alloys was discussed and an effective way to improve the wear reslstance of Al - Si alloys was put forward, that is increasing the silicon content.