Thermal Shock Resistance of Bauxite-based β-Sialon Bonded Corundum Materials

Thermal shock resistant properties of reaction sintered bauxite-based β-Sialon bonded corundum have been investigated, and the results are compared with those of Al_ 2O_ 3 based counterpart. It is found they all have very good thermal shock resistance. Their residual strength ratios after one thermal shock cycle at ΔT=1200℃ and ΔT=1350℃ are 61%~73% and 53%~65% respectively. Their critical temperature difference (TSR) is 600℃~800℃. TSR parameters are calculated based on thermal expansion, modulus of elasticity, and fracture toughness determined. The reasons for improving TSR of these composite materials are discussed.

Rheological Behavior of Bauxite-Based SiC-Containing Castables

Low cement (LC) and ultra low cement (ULC) bauxite SiC castables are important and high performance monolithic refractories and they have been widely used in iron making and incinerator linings. In this work, rheological behavior of LC and ULC bauxite based SiC containing castables has been studied, including the effects of SiC content and cement content on rheological properties of the castables. The results show that with an increase of SiC and cement content, rheological properties of the castables deteriorate. On the other hand, moderate amounts of SiC (4%～8%) and of calcium aluminate cement (2%～4%) have very slight influence on rheological properties, (i.e. when the castables are sheared their torque and yield torque only slightly increase with the shearing speed). The rheological characteristics of the castables follow Bingham fluid and always show shear thinning behavior.

High Temperature Property Development of Bauxite Based Bricks

Physical properties and microstructural evolution on firing of 3 types of bauxite based refractory bricks were carried out using techniques such as porosimetry, XRD and SEM. The groups differed from each other by progressive refining of the matrix or bond phase. It is revealed that such a refinement of the matrix can improve the high temperature properties of the bricks made from poor grade materials .

Research and Application Progress of Bauxite Based Homogenized Grogs in China

The progress of research and production of bauxite based homogenized grogs in China was summarized and the achievements of their application and modification in recent years were epitomized.In combination with the shortcomings existing in the research,production and application,the suggestions of bauxite based homogenized grogs for future development were put forward.

Spalling Resistant Bauxite Based Bricks for Cement Kiln

1 Scope This standard specifies the term, definition, classification, labeling, technical requirements, test methods, inspection rules, packing, marking, transportation, storage, and quality certificate of spalling resistant bauxite based bricks for cement kiln.

Bauxite Based Bricks for Steel Ladle

1 Scope This standard specifies the classification, technical requirements, test methods, inspection rules, packing, marking, transportation, storage, and quality certificate of bauxite based bricks for steel ladle linings.

Bauxite Based Refractory Bricks for Blast Furnaces

This standard is applicable to the bauxite based refractory bricks under the bosh for blast furnaces.

Bauxite Based Refractory Bricks for Hot Blast Stove

This standard specifies the technical require-ments, test method, inspection rules, packing, marking, transportation, storage and quality certificate of bauxite based refractory bricks for hot blast stove.

Effect of High Temperature Calcination on Structure and Properties of Bauxite-based Homogeneous Clinkers

In this paper,the effect of high temperature calcination on the structure and properties of bauxite-based homogeneous clinkers calcined at different temperatures for different durations was studied.The results show that with the rising of calcination temperature and the prolonging of holding time,the volume density of bauxite-based homogeneous clinkers increases and the apparent porosity decreases.After high temperature calcination,the linear expansion of bauxitebased homogeneous clinker is smaller than that of the non-calcined ones.Whether calcined at high temperatures or not,the thermal shock resistance of bauxite-based homogeneous clinkers is good.The crystalline phases of bauxite-based homogeneous clinkers are mainly mullite and corundum.There is more glass phase in the bauxite-based homogeneous clinkers without calcination.After calcination at high temperatures the glass phase content decreases significantly,and the mullite crystals develop better forming the cross-network structure.

β-Sialon Produced by Carbon Thermal Nitriding Reaction of Bauxite

β-Sialon was produced by carbon thermal nitriding reaction in N_2 gas atmosphere when the mixtures of bauxite and anthracite were put into vertical furnace. According to the mass loss of raw materials and the result of X-ray diffration (XRD) of products, the influences of the process parameters on the compositions and relative contents of products, such as the fixed carbon content, the flow of N2, the soaking time and the temperature, were researched.

Aluminum Reduction and Nitridation of Bauxite

The application of bauxite with low Al2O3 content has been studied in this paper and β-SiAlON has been obtained from two kinds of bauxites （Al2O3 content 68.08 mass% and 46.30 mass% respectively） by aluminum reduction and nitridation method. The sequence of reactions has been studied using thermal analysis （TG-DTA）, X-ray diffraction （XRD） analysis and scanning electron microscopy （SEM） with EDS. Compared with carbon thermal reduction and nitridation of aluminosilicates employed presently, the reaction in the system of bauxite-Al-N2 occurs at lower temperature. β-SiAlON appears as one of the main products from 1573K and exists stably in the range of the present experimental temperature. The microstructure of β-SiAlON obtained at 1773 K is short column with 5-10μm observed by SEM.

低碳Al_2O_3-β-SiAlON烧成滑板的热机械性能及显微结构

用10%的矾土基β-SiAlON替代普通铝碳烧成滑板中的部分炭素材料和刚玉,研究了低碳Al2O3-β-SiAlON烧成滑板的高温抗折强度、抗热震性能及显微结构.研究结果显示：这种滑板材料与普通烧成铝碳滑板材料相比较,碳含量降低了4%～6%,但在中、高温 （1000～1400 ℃） 强度有明显提高,抗热震性略有改善.其主要原因是引入的矾土基β-SiAlON与刚玉之间有较紧密的直接结合,起到了强化、韧化的作用.

矾土基β-Sialon结合刚玉-碳化硅复合材料抗冰晶石侵蚀性能的研究

采用静态坩埚法研究了矾土基β-Sialon结合刚玉-碳化硅复合材料在1000℃下的抗冰晶石侵蚀性能。结果表明:复合材料侵蚀量较少,侵蚀层厚度约1mm,侵蚀产物为NaAlSiO_4;渗透层深度约6mm,渗透速率随β-Sialon含量的增加而减小。复合材料渗透界面的分形维数值介于1.1～1.23之间,随Sialon含量的增加而减小。

不烧Al-Si复合低碳Al_2O_3-β-SiAlON材料的抗氧化性能

采用大试样高温热重分析仪研究了不烧Al-Si复合低碳Al2O3-β-SiAlON材料（MAC-F）的抗氧化性,并与Al-Si复合不烧铝碳滑板材料（MAC-S）进行了比较。结果表明（1）两种材料在250-1100℃氧化时的质量变化规律相似,在500℃以前均处于质量损失状态;从500℃开始试样处于质量增加状态,500-1100℃之间两种材料质量变化率的增加量差别不大;1100℃以上材料MAC-S的质量变化率的增加量明显提高,而材料MAC-F质量变化率的增加量稍有降低。（2）1500℃氧化后,材料MAC-F质量增加率明显低于材料MAC-S的,氧化层很薄,厚度仅0.5mm。材料MAC-F的氧化层中有较多的短柱状莫来石晶体,均匀地分布在刚玉骨架结构的空隙中,形成致密的结构,对氧气进入材料的内部起到了阻碍作用。其氧化层表面覆盖着一层由莫来石和少量玻璃相组成的光滑薄膜,更有效阻碍了氧气向内部的渗透。因此,材料MAC-F与材料MAC-S相比,抗氧化性能更为优异。

β-Sialon对金属复合不烧铝碳材料高温力学性能的影响

研究了加入矾土基β-Sialon对金属Al/Si复合不烧滑板材料高温力学性能的影响。加入矾土基β-Sialon后,材料具有如下特性:(1)高温抗折强度-温度曲线保持原有特性,在1 400℃时强度仍达到40MPa以上;(2)残余强度保持率随着矾土基β-Sialon加入量的增加而略有提高,抗热震性稍有改善。还讨论了材料的高温力学性能与物相组成和显微结构的关系。

矾土基β-SiAlON对Al_2O_3-MgO浇注料性能的影响

为了解新型原料矾土基β-SiAlON的使用性能,从而将其应用于实际,研究了矾土基β-SiAlON对MgOSiO_2-H_2O结合的Al_2O_3-MgO浇注料常规物理性能、高温抗折强度、抗热震性以及抗渣侵蚀性的影响。结果表明,加入矾土基β-SiAlON细粉对1 550℃、3h烧后试样的常规物理性能略有负面影响,对试样在1 400℃埋炭条件下的高温抗折强度影响不大,抗热震性有所改善。随β-SiAlON加入量的增加,试样的残余强度保持率增加(从16.27%增加到30.82%),但抗渣侵蚀性明显变差。

铝土矿尾矿协同钒钛磁铁矿尾矿制备刚玉质复相陶瓷

以铝土矿尾矿和钒钛磁铁矿尾矿为原料,经混料、成型和高温烧成等工艺制备了刚玉质复相陶瓷,研究了钒钛磁铁矿尾矿添加量、烧成温度等因素对制得复相陶瓷材料的物相、显微形貌及力学性能的影响规律。结果表明:当铝土矿尾矿与钒钛磁铁矿尾矿质量比为9∶1时,在1100℃下保温3 h制得刚玉质复相陶瓷材料的性能最优,其体积密度为2.71 g/cm^(3),抗压强度为276.9 MPa,抗折强度为67.3 MPa。

镁砂细粉含量对铝镁质浇注料性能的影响

研究了镁砂细粉含量对MgO -SiO2 -H2 O系结合的矾土基铝镁浇注料的流动性、常温物理性能及抗渣性的影响。结果表明 :随镁砂细粉含量的增加 ,浇注料烘后强度增加 ,但过多的镁砂细粉又使强度下降 ;随镁砂细粉含量的增加 ,浇注料的抗渣性逐渐恶化 ,特别是抗渣渗透性下降严重。

不同二氧化硅微粉对矾土基低水泥浇注料性能的影响

研究了4种理化性能不同的二氧化硅微粉对矾土基低水泥浇注料流动性、抗热震性和高温抗折强度的影响。结果表明:加入纯度高,杂质含量少,颗粒分布均匀、集中,表面光滑,自身流动性好的二氧化硅微粉,则浇注料的流动性好,抗热震性好,高温抗折强度高;加入碳和碱金属含量高,颗粒粒度偏粗,表面粗糙,自身分散性差的二氧化硅微粉,则浇注料流动性差,抗热震性差,高温抗折强度低。

硅线石对矾土基浇注料性能的影响

以矾土为主要原料，加入硅线石粉、SiO2微粉、活性Al2O3微粉、水泥等制备矾土基浇注料，研究了硅线石加入量（质量分数分别为0、4％、8％和12％）对浇注料常温性能和抗渣侵蚀性能的影响。结果表明：随着硅线石加入量的增加，浇注料的常温强度和体积密度下降，显气孔率增大；在浇注料中加入硅线石有助于提高试样的抗渣侵蚀性能，但加入质量分数大于8％时，试样抗渣侵蚀性能下降，渣渗透深度和侵蚀深度增加；硅线石加入质量分数为4％～8％时，浇注料的综合性能较好。