添加剂对尖晶石碳质材料性能的影响

为提高尖晶石碳质材料的抗热震性和抗冲刷性,以尖晶石、石墨和不同种类添加剂(铝-硅合金、硅粉、B4C、Si C)为原料,热塑性酚醛树脂为结合剂,在氮气保护下经950℃热处理后,制备了石墨含量为8%(w)的尖晶石碳质材料,探究了添加剂对尖晶石碳材料力学性能、抗热震性和抗氧化性的影响。结果表明:1)铝-硅合金或B4C能明显提高尖晶石碳材料的常温抗折强度,但会降低材料的抗热震性,B4C对材料的抗热震性最不利,硅粉和Si C对常温抗折强度影响不大,但能显著提高抗热震性;2)铝-硅合金或硅粉能显著提高材料的高温抗折强度,B4C或Si C对高温强度影响不大。3)经950℃热处理后,B4C对提高材料的抗氧化性作用不明显,单独加入硅粉、铝-硅合金和B4C复合添加均能提高抗氧化性能。     

镁尖晶石滑板的开发

以优质电熔镁砂为主要原料,通过引入镁铝尖晶石、单斜ZrO2、α-Al2O3粉,探讨了这些添加物对镁铝尖晶石滑板性能的影响。认为加入10％～20％的镁铝尖晶石及部分单科ZrO2对提高滑板抗热震性和高温抗折强度具有良好的作用。     

碳的种类对铝锆碳滑板性能的影响

分别对单独加入4%(质量分数)鳞片石墨、炭黑、沥青碳3种碳材料和加入不同碳材料(总质量分数4%)复合的铝锆碳滑板进行了树脂加入量、耐压强度、高温抗折强度、显气孔率、体积密度等物理性能以及抗氧化、抗热震性能比较。试验结果表明添加石墨可以实现低的树脂加入量,试样的显气孔率低,抗氧化性好;添加炭黑可以提高试样的强度;添加沥青碳,则可提高试样的抗热震性,但抗氧化变差;复合添加这3种碳材料,可以得到强度高、抗热震好的铝锆碳滑板试样。     

沥青种类和硝酸镍对铝碳材料性能与结构的影响

为了提高低碳铝碳耐火材料的抗热震性,分别选用环保沥青Carbores P、中间相沥青和高温沥青,以硝酸镍为催化剂,研究了沥青种类和催化剂对低碳铝碳材料常温和高温强度、抗热震性能及显微结构的影响,并探讨了沥青种类对催化改性低碳铝碳耐火材料中纤维碳生成的影响。结果表明:加入3种沥青的低碳铝碳试样,在催化剂作用下均生成了一定量的纤维状纳米碳;同时加入沥青和催化剂,更有利于提高铝碳材料的常温和高温强度及抗热震性;与加入高温沥青相比,加入环保沥青Carbores P和中间相沥青的催化改性铝碳材料中形成了较多且长的纤维状纳米碳,使材料的常温和高温抗折强度及抗热震性显著提高。     

硅粉对金属Al结合镁铝碳滑板材料性能的影响

金属Al结合镁铝碳质滑板抗侵蚀性优良,适用于浇铸钙处理钢.研究了加入硅粉对镁铝碳材料常规物理性能、抗氧化性、抗渣性的影响.结果表明,加入硅粉后,材料800℃ 和1000℃ 的烧后抗折强度(MOR)和高温抗折强度(HMOR)提高,但是加入过多硅粉会使材料1000～1600℃ 的烧后显气孔率升高,强度降低.加入适量的硅粉可以改善材料抗氧化性和抗侵蚀性.     

不同铝基原料对MgO-Al-C材料性能和显微结构的影响

以烧结镁砂骨料、电熔镁砂细粉、Al粉、N220炭黑为原料,酚醛树脂为结合剂,制备MgO-Al-C材料,研究了三种铝基原料(造粒氧化铝微粉、氧化铝空心微珠、六铝酸钙)对其常温抗折强度、高温抗折强度、抗热震性及抗氧化性的影响,并借助XRD和SEM对其物相组成及显微结构进行分析。结果表明,造粒氧化铝微粉是多孔结构,可吸收热应力,加入量为1%(质量分数,下同)时,可提高材料的常温抗折强度和抗热震性,明显改善材料的抗氧化性。氧化铝空心微珠是中空结构,可缓冲热应力,加入量为3%时,可明显提高材料的常温抗折强度,并具有较高的抗热震性和抗氧化性。六铝酸钙的热膨胀系数较低,可赋予材料较好的韧性,加入量不超过5%时,样品具有较好的抗热震性。     

堇青石对镁铝尖晶石质耐火材料抗热震性能的影响

镁铝尖晶石堇青石复合耐火材料是以各种级配的镁铝尖晶石和1 ～Omm的堇青石为骨料,0.088 mm镁铝尖晶石和二氧化硅微粉为基质,加入硅溶胶结合剂制成的烧结耐火材料.所获得的材料经过1200℃烧结具有优良抗热震性以及满足要求的其他性能,随着堇青石掺量的增加,材料的抗折强度降低,抗热震性增强.     

硼改性酚醛树脂加入量对铝碳材料性能的影响

为了改善铝碳材料的性能,以质量分数为40%的电熔刚玉(1~0.2 mm)、30%的Al2O3微粉(≤0.01mm)、25%的鳞片石墨(≤0.3 mm)、5%的添加剂(≤0.047 mm)为主原料,外加有机硼改性酚醛树脂粉和普通的酚醛树脂粉作为结合剂制备了铝碳材料。用热重分析法测定了树脂的残碳量,按相关标准测定了铝碳材料的常温抗折强度、高温抗折强度、显气孔率、抗氧化性、抗热震性,研究了硼改性酚醛树脂加入量(质量分数分别为0、2%、4%、6%、8%)对铝碳材料性能的影响。结果发现:硼改性树脂的残碳量较高;加入硼改性酚醛树脂不利于铝碳材料的强度,但可以提高铝碳材料的抗氧化性和抗热震性。     

石墨种类对尖晶石碳材料性能与结构的影响

以质量分数分别为88%的镁铝尖晶石、8%的石墨、1%的B4C、3%的铝硅合金粉为原料,外加7%的酚醛树脂和2. 5%的酒精制备了尖晶石碳材料,研究了石墨种类(鳞片石墨(+199和-199)、超细鳞片石墨SG、膨胀石墨EG)对该材料性能与结构的影响。结果表明:1)石墨含量至8%(w)时,石墨在基质中的分布不连续。鳞片石墨(+199和-199)对试样抗热震性和常温强度影响不大。加入3%(w)的超细鳞片石墨对试样的抗热震性较佳; 2)热震后试样的残余强度随膨胀石墨含量的增加稍有提高,而强度保持率最高试样的常温抗折强度则较低,综合考虑加入1%(w)的膨胀石墨较为适宜; 3)尖晶石碳棒头材料中石墨组成为鳞片石墨(+199和-199)和膨胀石墨,制备了多支塞棒进行了工业试验,结果表明该塞棒棒头不开裂,抗冲刷性能较好。     

无碳免烧刚玉-莫来石质滑板砖的研制与应用

以板状刚玉、莫来石、α-Al2O3微粉、铝粉、硅粉、碳化硅粉和新型结合剂为主要原料,通过研究铝粉加入量(质量分数分别为0、3%、6%、9%、12%、15%)、硅粉加入量(质量分数分别为2%、4%、6%、8%)及铝粉、硅粉加入比例(其质量比分别为15:0、12:3、9:6、7.5:7.5、6:9、3:12和0:15)对试样致密度、常温强度、高温强度、抗热震性和抗氧化性的影响,研制了无碳免烧刚玉-莫来石质滑板砖,并在多家钢厂投入实际使用。结果表明:1)随着铝粉、硅粉加入量的增加,试样的致密度、常温耐压强度、高温抗折强度、抗热震性、抗氧化性均逐渐提高,但铝粉、硅粉的加入量(w)分别超过9%和6%后,试样强度、抗热震性和抗氧化性提高均不太明显;2)随着硅粉加入比例的提高,试样常温耐压强度变化不大,高温抗折强度和抗热震性均逐渐提高;3)无碳免烧刚玉-莫来石质滑板砖能够满足2炉或3炉连滑的要求,应用效果优于铝碳质滑板砖。     

矾土基电熔尖晶石对矾土基浇注料性能的影响

为了开发矾土基电熔尖晶石的应用,在矾土骨料、纯铝酸钙水泥、Al2O3微粉、SiO2微粉等原料加入量不变(分别为65%、4%、4%和1%)的条件下,变化矾土基电熔尖晶石的加入量(分别为0、6%、8%、10%和12%)和电熔白刚玉细粉的加入量,研究了矾土基电熔尖晶石对矾土基浇注料常温物理性能、热态抗折强度、抗热震性以及抗渣性的影响。结果表明,与不加矾土基电熔尖晶石的浇注料相比,尖晶石加入量为6%~12%时,浇注料的常温性能相差不大,但热态抗折强度及抗热震性均有所提高,抗渣性有很大改善。     

Mechanical properties and microstructure evolution of MgO–Al–C slide plate refractories in presence of Al powder-modified magnesia aggregates

MgO–Al–C slide plate refractories were fabricated using sintered magnesia and modified sintered magnesia as aggregates, fused magnesia aggregates and fines, Al powder and carbon black (N220) as fines, and thermosetting phenolic resin as the binder. Al powder-modified magnesia aggregates were prepared and characterized and were introduced into the MgO–Al–C slide plate refractories. The effects of the modified aggregates on the properties, phase composition, and microstructure were investigated. 1) The Al powder-modified magnesia aggregates exhibited considerably high bonding strengths and low Al powder shedding ratios, thus meeting the preparation requirements of MgO–Al–C slide plate refractories. 2) At high temperatures, more needle-like and fibrous Al₄C₃, AlN and octahedral MgAl₂O₄ were generated on the surface of the modified magnesia aggregates, which enhanced the bond between the matrix and the aggregates and increased the hot modulus of rupture of the material. 3) Non-oxide Al₄C₃ and AlN phases were formed in situ and had high thermal conductivity and low coefficient of expansion; this could relieve the internal thermal stress of the material and create a toughening effect, improving the thermal shock resistance of the material.     

Effects of Tabular Corundum Types on Properties of Corundum-spinel Castables

The corundum-spinel castables were prepared by six kinds of tabular corundum as aggregates,respectively,and their linear change rate on heating,apparent porosity,bulk density,cold modulus of rupture,cold crushing strength,hot modulus of rupture and thermal shock resistance were compared and studied. The results show that: 1) the six tabular corundum materials have similar main chemical composition but their physical properties vary for the different technical procedures which result in different properties of castables; 2) the optimal properties of corundum-spinel castables correspond to different tabular corundum types,so the corundum type shall be selected according to the application of the castables.     

Effect of Andalusite Addition on Properties of Chrome-corundum Bricks

In order to improve the thermal shock resistance of chrome-corundum bricks, different amounts of andalusite were added to the formulation of chrome-corundum bricks to replace the equivalent white fused corundum with the same particle size. After mixing, shaping, drying and firing, the density, the cold strength, the cold wear resistance, the hot modulus of rupture and the thermal shock resistance were tested. XRD, SEM and elemental surface scanning were used to characterize the specimens. The results show that:(1) the volume expansion of andalusite mullitization reduces the apparent porosity of chrome-corundum bricks;(2) the density and the hardness of mullite are lower than those of corundum so the decrease of the corundum content in brick leads to the decrease of the bulk density, the strength and the cold wear resistance;(3) the cross-distributed columnar mullite in the matrix can effectively improve the hot modulus of rupture and the thermal shock resistance of the specimens;(4) considering comprehensively, the andalusite addition shall not exceed 18%.     

不同碳含量对镁碳砖性能的影响

研究了碳含量的变化对镁碳砖抗渣侵蚀性、抗氧化性能、高温抗折强度和热震稳定性的影响。研究结果表明：随碳含量增加,镁碳砖的体积密度、耐压强度降低;碳含量在6%~8%时,镁碳砖的高温抗折强度、热震稳定性、抗渣侵蚀性及抗氧化性能好;碳含量低,镁碳砖的抗渣侵蚀性降低;碳含量为14%时,镁碳砖的抗氧化性能最差。     

Effect of hollow spheres on the properties of lightweight periclase-magnesium aluminate spinel refractories

This study presents new lightweight periclase-magnesium alumina spinel refractories for the working lining of cement rotary kilns in which magnesium alumina spinel hollow spheres are used to replace conventional dense fused magnesia-aluminate spinel aggregates. The effects of adding spinel hollow spheres on the physical properties, mechanical strength, thermal conductivity, and slag resistance of the samples were explored. The results showed that compared with the sample prepared with dense aggregates, the sample prepared with hollow spheres had a 10.3% higher cold compressive strength, 44.1% higher modulus of rupture (MOR), and lower bulk density. Additionally, with increasing hollow spheres content, the thermal conductivity decreased from 3.79 W/(m·K) to 2.53 W/(m·K), and the high-temperature MOR increased from 2.82 to 4.09 MPa. The highest residual strength ratio was 90.73% (15 wt.% hollow spheres), which is 1.17 times that of the sample prepared without hollow spheres. Moreover, microstructure and energy dispersive spectroscopy of crucible specimens after corrosion by cement clinker showed that specimens with 15 wt.% hollow sphere additions had a better slag resistance. Introducing hollow spheres reduced the thermal conductivity of the refractories, providing a new strategy for improving the heat insulation performance of kiln linings.     

Effects of different particle size of spinel and Y2O3 additive of the periclase-spinel refractory on the sintering densification and corrosion resistance to copper smelting slag

In order to analyze the sintering densification and copper smelting slag corrosion resistance of periclase-spinel refractories, the periclase-spinel refractories were prepared with fused magnesia, magnesia-rich spinel, industrial alumina, and yttrium oxide as the main raw materials. The different particle sizes of spinel in material and with or without Y₂O₃ additive were studied. The study demonstrated that: (1) The different particle sizes of spinel in periclase-spinel refractories can result in different effects. Adding particle spinel to the refractory can improve the strength and corrosion resistance of the periclase-spinel refractories. The addition of spinel and magnesia powders in the matrix resulted in cracks due to the great difference of coefficient of thermal expansion between magnesia and spinel. The reduction in bulk density and strength of the material decreased slag penetration resistance because of its poor sintering properties. While adding the alumina in the matrix can further fill the crack and prevent slag penetration by the volume expansion of in-situ reaction to form spinel. (2) The periclase-spinel refractories can be reacted with Cu slag to form a Mg₂FeO₄ insulating layer as the iron ion becomes oxidized. Adding Y₂O₃ in periclase-spinel refractories can result in grain boundary phase reconstruction, which can promote sintering densification, improve the slag physical infiltration resistance, and improve the chemical corrosion resistance of materials.     

h-BN加入量对低水泥刚玉质浇注料性能的影响

为了提高低水泥刚玉质浇注料中温处理后的强度和抗热震性,在其配料中引入不同量的h-BN粉(其质量分数分别为0、0.5%、1%、1.5%和2%),经成型、养护、脱模、烘干、750℃热处理后,检测试样的体积密度、显气孔率、常温抗折强度、常温耐压强度、抗热震性,并进行XRD分析。结果表明:随着h-BN加入量的增加,750℃处理后试样的显气孔率有所减小,体积密度逐渐减小,常温耐压强度逐渐增大,常温抗折强度也呈增大趋势,抗热震性逐渐改善。可见,加入h-BN有助于提高低水泥刚玉质浇注料中温处理后强度和抗热震性。