Effect of waste serpentine on the properties of basic insulating refractories

Basic insulating refractories were fabricated by the pressing route using dead-burned magnesia, pure calcined alumina, expanded perlite, and calcined waste serpentine as starting raw materials in four compositions from F1 to F4. Periclase and forsterite were major phases in F1 and F2 compositions, while spinel was also detected in the XRD patterns of F3 and F4 samples. Quantitative phase analysis showed that F4 sample sintered at 1450?°C has the highest forsterite content among all other samples. On the other hand, it has lower thermal conductivity compared to F1 to F3, and even lower than aluminosilicate IFBs with the same bulk density. It is concluded that forsterite is a highly insulating material, compared to periclase, corundum, periclase-spinel, aluminosilicates, such as mullite, etc.     

Synthesized K2O·11Al2O3 as sagger matrix for the preparation of Li-ion battery cathode materials at high temperatures

Refractory materials such as mullite, andalusite, forsterite, and cordierite are generally used to prepare saggers for the calcination of Li-ion battery Li(Ni_xCo_yMn_z)O₂ (LNCM) cathode material. However, these compounds are prone to be attacked by the LNCM materials, thereby leading to short life spans and contamination of the Li-ion battery cathode materials. To improve the corrosion resistance of refractory sagger materials, the most clear cut-way is enhancing the corrosion resistance of matrix using a new refractory component. Potassium aluminate (K₂O·11Al₂O₃, KA₁₁) with an excellent corrosion resistance against alkaline oxide was synthesized via solid-state method using potassium carbonate (K₂CO₃) and industrial alumina powder (Al₂O₃). Interactions between KA₁₁ and LNCM cathode materials at 800°C–1100°C were characterized by refractory-LNCM precursor laboratory-scale tests to understand the corrosion behavior of KA₁₁. The microstructure and phase composition of synthesized KA₁₁ and the calcined KA₁₁-LNCM mixture cylinders were analyzed with SEM and XRD. The observations reveal that KA₁₁ shows a better corrosion resistance to LNCM materials compared with mullite, cordierite, and forsterite. The addition of synthesized KA₁₁ also favors the thermal shock resistances of mullite-based sagger materials.     

Complex Phase Equilibria in Refractories Design and Use

The current applications of phase diagrams and thermodynamic calculations to studies of refractories are reviewed highlighting links to microstructural analyses. Improved understanding of microstructural evolution and chemical corrosion mechanisms has resulted from such work. The limitation of the calculations/diagrams to thermodynamic equilibria has led to imaginative attempts to incorporate some dynamic aspect in them so they are more relevant to practical conditions. These include varying temperature to model a temperature gradient, P _O2 to model atmosphere permeation into a brick, slag/refractory ratio to model slag penetration and altering the slag composition after reaction with the fine matrix phases. The potential future development of such techniques is discussed.     

β-Sialon-Al2 O3-SiC系复相材料的研制和性能

研究了在 15 0 0℃的流动氮气中 ,用Al粉、Si粉、Al2 O3粉、刚玉和SiC的颗粒及细粉直接制备 β Sialon -Al2 O3-SiC系复相材料的氮化烧结技术。XRD和SEM分析表明 ,结合相 β Sialon的显微形貌随刚玉量的增加由纤维状向棱柱状转变 ,发育良好。复相材料的高温抗折强度高于常温抗折强度。抗热震试验结果显示 :添加适量的刚玉对β Sialon -SiC复相材料和添加适量的SiC对β Sialon -刚玉 复相材料都具有良好的增韧效果 ,这是β Sialon的纤维增强及柱状晶体原位自补强增韧和复合弥散相增韧综合作用的结果。抗碱和抗高炉渣试验均显示了该复相材料优良的抗碱和抗铁渣侵蚀能力。     

铝炭制品防氧化涂料的作用机理

采用热分析等研究方法，分析了铝炭制品的氧化过程，研究了以阻断铝炭制品与氧气接触来实现防氧化的硼硅酸盐系涂料的高温特性和防氧化机理，以及不同结合剂对涂料与铝炭制品界面行为的影响。     

炉外精炼用耐火材料提高寿命的途径及其发展动向

结合VOD与RH介绍了造成炉外精炼蚀损严重部位的原因。从MgO-Cr2O3、MgO-CaO、MgO-C、MgO-CaO-C、MgO-MgO·Al2O3等耐火材料性能及在精炼中的作用介绍了如何选择耐火材质;从接触角、熔渣粘度、形成高熔点化合物、气孔微细化以及炉渣成分控制、双饱和与精炼温度等方面介绍了提高炉外精炼用耐火材料寿命的途径。最后结合镁铬、镁钙、MgO-C、镁钙碳与无铬耐火材料介绍了炉外精炼用耐火材料的发展动向,并对MgAlON结合镁质耐火材料在炉外精炼中的研究与应用进行了评估与预期。     

钢液对连铸用含碳耐火材料的侵蚀作用研究

采用中频炉的实验室模拟试验(试验条件:钢液温度1600℃,浸入时间30min,气氛分别为空气和真空)和通过对用后耐火材料的显微结构分析,研究了钢液对3种连铸用含碳耐火材料(Al2O3-C、MgO-C和ZrO2-C)的侵蚀作用。结果表明,脱碳层的形成及钢液中夹杂物与脱碳层中耐火氧化物的反应是材料蚀损的主要原因。因此,在含碳耐火材料接触钢液的表面形成致密耐火层,能有效抑制钢液对连铸用含碳耐火材料的侵蚀。     

自主创新,发展新型优质耐火材料

讨论了今后我国耐火材料品种、结构、调整、升级的问题,应当以自主创新为主旋律,充分利用资源优势发展有自己特色的新型质合成原料和高效制品,还介绍了近两三年来这方面的一些科技成果。     

MgO-CaO-TiO2系材料的烧结性能及抗水化性能

以白云石、工业钛白粉、轻烧镁砂为原料配制了不同组成的MgO-CaO-TiO2材料,分别于1500℃、1550℃、1600℃、1650℃保温3 h煅烧后,研究了材料的烧结性能,并采用蒸压法(0.1 MPa下蒸压2 h)研究了烧后试样的抗水化性能.研究结果表明1550～1600℃煅烧后,试样均达到了良好的烧结,相对密度达到92%以上,原始配料中的CaO全部转化成了不易水化的CaO·TiO2,因而所有试样均表现出优良的抗水化性能.