富铝尖晶石对镁质耐火材料抗侵蚀性的影响

研究了富铝尖晶石对镁质耐火材料抗钢渣与抗钙处理钢侵蚀性的影响。结果表明 :随着富铝尖晶石加入量的增加 ,镁质耐火材料的抗钙处理钢和钢渣熔蚀性逐渐减弱 ,而抗钢渣渗透性逐渐增强 ;纯镁质和镁尖晶石质耐火材料在抗钢渣与抗钙处理钢侵蚀方面远远优于铝锆碳质材料     

利用铝铬渣与废弃镁碳砖合成镁铝尖晶石材料

以铁合金厂铝铬渣和钢厂废弃镁碳砖为主要原料,通过固相烧结反应合成MgAl2O4材料,研究分析铝铬渣与废弃镁碳砖细粉比例关系对合成MgAl2O4材料组成和结构的影响.用XRD、SEM及Rietveld quantification软件对材料中结晶相组成和结构进行表征.结果表明:铝铬渣和废弃镁碳砖细粉经1500℃保温2h煅烧,可以合成出镁铝尖晶石材料.当镁碳砖含量为40％,铝铬渣为60％时,合成材料微观结构中出现典型的镁铝尖晶石八面体形貌特征,结晶相发育完整,结构致密,镁铝尖晶石含量达到94％.     

1600℃氮气气氛下Al对Al2O3–MgO材料中尖晶石物相演变的影响

探究了在1 600℃氮气气氛下金属Al对Al₂O₃–MgO耐火材料中尖晶石物相演变的影响。结果表明,金属Al显著改变了尖晶石物相的组成、形貌和反应路径。未添加金属Al时,氧化镁与氧化铝反应生成镁铝尖晶石;镁铝尖晶石与其包裹的氧化铝颗粒发生固溶体反应形成一次富氧化铝的镁铝尖晶石。C–O₂反应使体系氧分压持续降低,氧化镁分解产生的Mg(g)与周围的氧化铝和一次富氧化铝的镁铝尖晶石发生置换反应,形成二次富氧化铝的镁铝尖晶石和金属Al(l/g)。在高温氮气下,金属Al(l/g)氮化形成氮化铝后,与上述一次或二次富氧化铝的镁铝尖晶石反应形成镁阿隆尖晶石(MgAlON)尖晶石。将金属铝引入到Al₂O₃–MgO耐火材料后,含铝气相物质——Al(g)和Al₂O(g),沿耐火材料中的气孔或孔隙扩散传质。一方面,Al(g)和Al₂O(g)氮化反应形成氮化铝,固溶强化并提升MgAlON尖晶石中氮元素的含量;另一方面,Al(g)、Al₂...     

镁铝尖晶石对铝钛渣合成钛酸铝的影响

为降低合成钛酸铝材料的原料成本,以铁合金厂铝钛渣为主要原料,按71.5%(w)铝钛渣和28.5%(w)二氧化钛粉的基础配方,分别外加质量分数1%、2%、3%和4%的添加剂镁铝尖晶石,以聚乙烯醇溶液为结合剂,经湿磨、干燥、机压成型后,分别在1 400、1 450和1 500℃保温2 h合成了钛酸铝材料,然后检测其体积密度和显气孔率,运用XRD和SEM分析物相组成和显微结构,并运用X’Pert Plus软件计算钛酸铝的晶格常数。结果表明:镁铝尖晶石中Mg2+对钛酸铝中Ti4+的置换作用导致钛酸铝的晶格常数增大,晶格发生畸变,从而促进钛酸铝的合成及其烧结;随着合成温度的升高,上述置换作用和促进钛酸铝合成、烧结的效应增强。     

LiCoO2合成过程对镁铝尖晶石陶瓷侵蚀的研究

研究了LiCoO2合成粉体过程对镁铝尖晶石陶瓷的侵蚀,并探讨了相关侵蚀机制.研究结果显示,经历10次的LiCoO2粉体合成过程后,镁铝尖晶石陶瓷的平均被侵蚀深度仅约100μm;其侵蚀机制为:含锂化合物先于含钴化合物对镁铝尖晶石陶瓷进行侵蚀并形成LixMyOz(M=Al/Mg)化合物,含钴化合物进一步侵蚀渗透形成LixMyOx(M'=Al/Mg/Co)化合物并从LixMyOz(M=Al/Mg)化合物中析出.研究认为,用镁铝尖晶石陶瓷制备合成钴酸锂粉体用匣钵具有良好的抗侵蚀性能.     

镁铝尖晶石钢包浇注料的生产及使用效果

以镁铝尖晶石料和镁砂共磨粉为主要基质，以Ａｌ２Ｏ３≥８５％的特级高铝矾土为骨科，以新型复合聚磷酸盐为结合剂生产出了新型钢包浇注料，在连铸钢包上使用寿命比原用的铝镁浇注料提高一倍以上。     

CeO2对形成镁铝尖晶石转变温度的影响

采用固相烧结法合成镁铝尖晶石粉末,通过X射线衍射分析尖晶石的相变转变温度。结果表明：CeO₂对相变反应具有促进作用,添加3%CeO₂能够使尖晶石的相变转变温度由1500℃降低到1300℃;随着温度的升高,尖晶石生成量增加。加入稀土CeO₂含量大于1%时,随着CeO₂含量的增加,稀土CeO₂对尖晶石的相变温度的促进作用增强;CeO₂含量小于3%时,保温时间对尖晶石的形成影响不大,在1500℃下,当CeO₂含量为5%时,随着保温时间的延长,尖晶石的含量增加。对温度、保温时间和稀土加入量综合考虑,生产中添加3%CeO₂,1300℃煅烧保温2h为宜。     

利用高碱铝铬渣合成镁铝铬尖晶石

利用高碱和铝铬渣和轻烧镁砂合成镁铝铬尖晶石,同时,Ｎａ２Ｏ和Ｋ２Ｏ在高温下挥发,显著降低了合成料中的碱含量。     

煤熔渣对镁铝尖晶石质耐火材料的侵蚀机制

为了实现水煤浆气化炉炉衬材料的无铬化,研究开发合适的耐火材料代替水煤浆气化炉用高铬砖,以尖晶石骨料及细粉、α-Al_2O_3微粉和轻烧Mg O微粉为原料,于1 600℃保温5 h烧成,制备了φ50 mm×40 mm、内孔为φ25 mm×25 mm的镁铝尖晶石质坩埚试样。采用静态坩埚法,借助XRD、SEM+EDS研究了高温煤熔渣对试样的侵蚀行为。结果表明:1)侵蚀后的镁铝尖晶石材料结构疏松,出现较明显的裂纹,煤熔渣完全渗入试样内部。2)经煤熔渣侵蚀后的镁铝尖晶石材料,物相组成发生变化,除原有的镁铝尖晶石外,还有新物相镁铁铝复合尖晶石相存在。3)煤熔渣对镁铝尖晶石材料的侵蚀机制是物理渗透为主,化学熔蚀为辅。     

AlON对Al2O3-MgO钢包浇注料抗渣性的影响

在Al2O3-MgO钢包浇注料中引入6%的AlON后,用静态坩埚法考察了添加AlON的浇注料在不同气氛条件下1600℃3 h的抗渣性,采用SEM分析了试样的显微结构.结果表明在埋炭保护条件下,添加AlON后浇注料的抗渣性得到改善;在大气气氛中,未加抗氧化剂的试样的抗渣性恶化;分别加入SiC、Si和B4C作抗氧化剂后,抗渣性虽有所改善,但仍比空白试样和含AlON试样在埋炭保护条件下的抗渣性稍差.抗渣性与加入到浇注料中的AlON是否氧化和材料内部能否形成和保持由尖晶石、六铝酸钙和刚玉构成的相组合有关.     

添加铝铬渣的钢包水口座砖的研制和应用

为降低钢包水口座砖的生产成本,在0#浇注料配方(w):电熔白刚玉骨料70%、电熔白刚玉细粉10%、α-Al2O3微粉+镁铝尖晶石+氧化铬微粉15%、铝酸钙水泥5%的基础上,以等粒度铝铬渣骨料全部取代电熔白刚玉骨料(1#配方),再在1#配方的基础上以铝铬渣细粉全部取代电熔白刚玉细粉(2#配方),配制成3种浇注料,经搅拌、振动浇注成型、养护、干燥以及1 100和1 550℃热处理后,检测试样的体积密度、强度、抗热震性和抗侵蚀性等性能。结果表明:1)110℃烘干后,与0#试样相比,1#试样的体积密度变化不大,显气孔率略有升高,抗折强度略有降低,耐压强度显著提高;而2#试样的各项性能均有不同程度的下降。2)1 100和1 550℃热处理后,1#试样的各项性能指标均有比较明显的改善,高温抗折强度明显提高,抗渣侵蚀性优良,但抗热震性下降;而2#试样除高温抗折强度外其余各项性能下降明显。按综合性能最佳的1#配方制备的钢包水口上座砖在某钢厂60 t钢包上使用,1次寿命达80~90炉次,修补后寿命达110~120炉次,与钢包寿命同步。     

LF精炼钢包渣线用含铬铝镁浇注料的研制

以特级矾土、电熔镁砂、铬刚玉为主要原料制备了LF精炼钢包渣线用含铬尖晶石质浇注料,并在抗渣蚀性及抗热震性方面同现场使用的普通铝镁浇注料进行了对比。结果表明:与现场使用的铝镁浇注料相比,新研制的含铬尖晶石浇注料具有更好的抗热震性及抗渣蚀性,在济钢55t钢包上使用寿命达到79炉次。     

Molten salt synthesis and formation mechanism of magnesium aluminate spinel using different shape Al2O3 as the templets

In order to verify the “Al₂O₃-template-formation” mechanism of magnesium aluminate (MA) spinel proposed previously using Al₂O₃ and MgO micro-powders as raw materials, in this work, MA spinel was synthesized by nanograined, plate-like, and fibrous Al₂O₃ in LiCl molten salt at 1150 °C for 3 h, respectively. The products were characterized by XRD, SEM, TEM, and EDS techniques, and the grain size of the products and raw materials were analyzed. The results showed clearly that the MA spinel was initially nucleated and subsequently developed to octahedral crystal. When the reaction further took place, when using nanograined Al₂O₃, the newly formed MA spinel seeds initially moved and attached to the surface of the large octahedral MA spinel crystal, and they were subsequently engulfed by the large MA spinel crystal, which further grew via layer-by-layer to become micro-sized crystal. Using plate-like or fibrous Al₂O₃ raw material, MgO diffused continuously into the interior of Al₂O₃ to form MA spinel with a gradient growth from surface to depth. These revealed that whatever shape of Al₂O₃ was used, the synthesis of MA spinel was governed by “Al₂O₃-template formation mechanism”, i.e., by the reaction of MgO diffusion into the Al₂O₃ templet in the molten salt.     

铝铬砖和镁铬砖抗艾萨炉炉渣蚀损的模拟研究

采用回转抗渣法模拟研究了试验温度、保温时间和熔渣加入量等因素对铝铬砖和镁铬砖抗艾萨炉炉渣侵蚀能力的影响。用SEM、EDAX及XRD等方法,对抗渣试样的显微结构和矿物组成进行了分析研究。结果表明:随着侵蚀温度的升高、保温时间的延长及炉渣加入量的增加,铝铬砖和镁铬砖的侵蚀面积增大;熔渣渗入铝铬砖后,形成铁铝尖晶石和铁铬尖晶石保护层,阻止了熔渣的侵蚀;三种耐火材料抗艾萨炉炉渣侵蚀能力由强到弱为:铝铬砖>电熔再结合镁铬砖>直接结合镁铬砖。     

Preparation and characterization of novel nonstoichiometric magnesium aluminate spinels

Magnesium aluminate spinel is of great importance for nuclear industry, and its structure, showing a great impact on properties, is sensitive to the composition. In order to explore the stoichiometric effect on structure and properties of spinels, several different spinel compositions with MgO·nAl₂O₃ (n?=?0.5–2.4) were synthesized via solid state reaction. Synthetic samples were characterized by X-ray diffraction, scanning electron microscope and nanoindentation tests. The results of XRD and SEM indicate that the single-phase magnesia alumina spinels have been prepared successfully for the first time ranging from n?=?0.667 to n?=?1.5, which is beyond the previous reported ranges of n$\ge$ 0.91. The hardness and modulus decrease with increasing n, implying further that the nonstoichiometric spinel crystal structures are likely to exhibit superior mechanical properties.     

Corrosion of chemical-mineralogical gradient submicron-porous Al2O3-MgAl2O4 composite in contact with molten converter slag

Penetration resistance and corrosion mechanism of a novel chemical-mineralogical gradient submicron-porous corundum-spinel composite (A90) to converter slag were investigated and compared to its dense corundum counterpart. Slag-penetration resistance of A90, due to its special submicron-pore structure, is superior to that of the corundum counterpart. Gradient Al₂O₃-rich spinels pre-embedded on the inner-surfaces of the pores are essential for making the slag deficient in Fe²⁺ and Fe³⁺ and CaO-rich. The resultant CaO-rich slag reacted with the corundum matrix of A90, building up a continuous dense layer composed of tightly interlocked highly refractory tabular CaA1₁₂O₁₉ and thus suppressing the further slag penetration and corrosion. Due to the lack of MgO in the corundum/molten-slag reaction system, large amounts of low melting iron oxides still remained in the liquid slag, making it much less viscous, so it could penetrate readily the corundum substrate via the grain boundaries in it at the test temperature.     

Effect of Eu2O3 on sintering densification and corrosion resistance of magnesium aluminate spinel

The effect of the doping amount of Eu₂O₃ on the densification behaviour of magnesium aluminate spinel (MAS) and its corrosion resistance to aluminium electrolyte were studied. The relative density, phase composition, micro morphology and hardness of the sintered samples were characterised by Archimedes’ drainage method, X-ray diffractometer, scanning electron microscope and automatic micro Vickers hardness tester. Results showed that the doping of Eu₂O₃ was conducive to the densification of MgAl₂O₄. When the content of Eu₂O₃ was 3 wt.%, the relative density of MAS was the largest (99.32%), the microstructure was more compact and the hardness was the largest (2293.4 kgf/mm²). The MAS sample with 3 wt.% Eu₂O₃ had the best corrosion resistance to aluminium electrolyte, and the corrosion depth was 80.99 μm. It was speculated that the electrolyte may penetrate into the sample through the micropores, and the fluoride salt chemically reacted with MgAl₂O₄ to form Al₂O₃, NaF and MgF₂.     

Enhancing mechanism of improved slag resistance of Al2O3-spinel castables added with pre-synthesized (Al,Cr)2O3 micro-powder

In order to enhance the slag resistance of Al₂O₃-spinel castables, (Al,Cr)₂O₃ is added into Al₂O₃-spinel system as a pre-synthesized micro-powder. Firstly, (Al,Cr)₂O₃ micro-powder is synthesized by sintering under reduction conditions to prevent the formation of hexavalent chromium. The Al₂O₃-spinel castables are prepared using tabular alumina, fused spinel, α-Al₂O₃ micro-powder, calcium aluminate cement and (Al,Cr)₂O₃ micro-powder as the raw materials. The bulk density, porosity, mechanical properties, and slag resistance of the samples are tested. Afterward, the effects of (Al,Cr)₂O₃ micro-powder (0–3 wt%) on the slag resistance and microstructures of the Al₂O₃-spinel castables are assessed by X-ray diffraction (XRD) and energy-dispersive (SEM-EDS) analysis. The results show that the addition of (Al,Cr)₂O₃ micro-powder can could inhibit the deteriorating effects of Cr³⁺ on the mechanical properties of the samples. The microstructure results also shows that with the addition of the (Al,Cr)₂O₃ micro-powder, a secondary solid solution of Ca(Al,Cr)₁₂O₁₉ formed, causing the unit cell to become larger. In the slag erosion area, CA₆ crystals formed with network-like interwoven structures, high density, and greater thickness. These characteristics significantly reduce the erosion and permeability indices of the castables, and improve the slag erosion resistance of the material.