煅烧制度对合成轻质微孔莫来石骨料性能的影响

以工业氧化铝、硅石粉为主要原料,采用加入可燃物的方法制备莫来石轻质合成料。根据坯体料的DSC-TG和大试样热重分析设置了不同的煅烧制度,比较了两种煅烧制度:一种为单调升温,然后保温;另一种为在高低两个温度分段保温。研究了两种煅烧制度对合成轻质微孔莫来石骨料莫来石化率及体积密度、气孔率性能的影响。结果表明,无烟煤约在600℃烧失,坯体料自1200℃开始发生莫来石化反应,试样经1350℃×6h热处理后的孔径分布3￣7μm左右,莫来石转化率60%。     

莫来石轻质骨料的制备及性能研究

以蓝晶石细粉为原料,核桃壳粉为造孔剂,硅溶胶为结合剂,制备了莫来石轻质骨料。研究了煅烧温度(分别为1 300、1 400、1 500、1 600℃,保温时间均为180 min)和保温时间(分别为60、120、180 min,煅烧温度均为1 500℃)对莫来石轻质骨料体积密度、显气孔率、烧后线变化率、物相组成和显微结构的影响。结果表明,在1 500℃保温60 min所得莫来石轻质骨料的综合性能最优,其体积密度为1.18 g·cm^-3,显气孔率为59.8%,烧后线变化率为2.58%,莫来石相含量为86%(w)。     

莫来石—氧化锆骨料加入物对高铝耐火材料热机械性能的影响

本文研究了含有不同数量电熔莫来石-锆砂的高铝砖的机械性能和抗热震破坏性。对于所有组成而言,上述性能的趋向是由玻璃相的作用以及由氧化锆相转变所形成的网状微裂纹所决定的。试验取得的结果与从机械和物理性能推算的理论参数R″和Rst有关。     

蓝晶石含量对球形45莫来石轻骨料浇注料显微结构及性能的影响

为改善含球形45莫来石轻骨料浇注料的体积稳定性和显微结构,引入了不同含量的蓝晶石(w=8%、10%、12%、14%、16%).采用X-射线衍射仪、扫描电子显微镜等对1300℃保温3 h煅烧后试样的物相组成、显微结构与性能进行了表征.研究发现:随着蓝晶石含量的增加,1300 ℃煅烧后试样的强度显著降低,线变化率由-0.87%逐渐增加至0.64%,骨料基质结合程度先变好后变差.综合考虑各项性能,含12%蓝晶石的试样综合性能最优:1.73 g/cm3的体积密度,36.8%的显气孔率,29.3 MPa的耐压强度,0.18%的线变化率,0.58 W/(m· K)的导热系数(800 ℃)和1339 ℃(T0.6)的荷重软化温度.     

以托帕石为原料的莫来石耐火骨料的制备及其烧结机理

以澳大利亚托帕石精矿为原料,经湿法球磨、烘干后以150MPa压力压制成20×20mm的试样,再分别经1 300、1 400、1 500、1 600、1 700和1 750℃煅烧3h,通过测试试样煅烧后的线变化率、显气孔率、体积密度、吸水率和常温耐压强度,研究了煅烧温度对试样烧结性能的影响,分析了烧结机理。结果表明,试样经1 300℃煅烧3h后,托帕石完全转化为柱状莫来石晶须。随煅烧温度升高,莫来石晶须逐渐烧结;试样经1 750℃煅烧3h后,显气孔率为1.4%,体积密度为2.89g/cm3,常温耐压强度为648MPa。烧结机理分析表明:试样在1 300~1 500℃为固相烧结,烧结传质方式为体积扩散;当煅烧温度高于1 600℃时,试样中生成少量的液相,液相的存在起到烧结助剂作用,使试样致密化过程明显加快,晶粒尺寸显著增大。     

电熔锆莫来石研制

电熔锆莫来石研制施毓斐（上海日用玻璃制品公司耐火材料部２０００２０）ＡｎＩｎｖｅｓｔｉｇａｔｉｏｎｏｆＥｌｅｃｔｒｏ－ＭｅｌｔｅｄＺｉｒｃｏｎｉａＭｕｌｌｉｔｅ￥ＳｈｉＹｕｆｅｉ（ＳｈａｎｇｈａｉＤｏｍｅｓｔｉｃＧｌａｓｓｗａｒｅＣｏ．，Ｒｅｆｒａｃ...     

莫来石相定量分析初探

用化学分析方法检测了莫来石－刚玉系统中,莫来石相,刚玉相和玻璃相的相含量,为莫来石－刚玉质窑具质量评价提供一种检测依据。     

莫来石推板砖的研制

介绍了氮窑用莫来石推板砖的研制过程。通过对进口产品的剖析 ,采用正交法筛选出配方 ,产品理化指标为 :Al2 O3～ 70 % ,常温抗折强度～ 1 0MPa ,高温抗折强度～ 1 0MPa,荷重软化温度≥ 1 70 0℃ ,线膨胀率 <0 .5% ,使用寿命一般为50次 ,最高可超过 1 0 0次     

莫来石晶粒柱状生长对莫来石基陶瓷力学性能的影响

将AlF3加入莫来石(莫来石/氧化锆)先质中,生坯试样经密闭处理及常压烧结,可获得莫来石柱状晶粒生长.实验结果表明:莫来石柱状生长使莫来石陶瓷在其强度不下降的前提下,韧性提高,且随柱状晶粒粒径增大而增加有类似架桥作用.ZTM(含AlF3)材料韧性的提高是由于莫来石柱状晶粒生长使t-ZrO2形态发生了变化,具有较大长径比或有尖角的不规则形态的t-ZrO2晶粒容易发生应力诱导相变,使材料力学性能得到明显提高.     

Synthesis of Mullite Whiskers

Mullite whiskers were synthesized by heating a mixture of SiO₂ and silicon in an alumina tube reactor under a flow of H₂ and CF₄. The length and diameter of the whiskers were several hundred micrometers and >15 μm, respectively. It was postulated that a vapor phase reaction between SiF₄ and AlF₃ made possible the synthesis of the large mullite whiskers.     

连续莫来石陶瓷纤维的制备研究

采用异丙醇铝和氯化铝作铝源,正硅酸乙酯作硅源,通过溶胶-凝胶法合成含有Al-O-Si长链的溶胶,干法纺丝制备莫来石连续纤维.对溶胶及凝胶进行了FT-IR分析和TG-DTA分析,研究了其光谱和热学性质,并对烧结后的纤维做SEM观察、XRD分析、XRF分析等.测试结果表明,在前驱体溶胶中含有Al-O-Si及Si-O-Si等为骨架的长链,具有较好的可纺性和稳定性;所得纤维直径在十几个微米,晶粒比较细小,在100～200nm之间;烧结过程中没有其它晶相出现.     

自生晶须强韧化莫来石材料的研究

采用溶胶－凝胶法制备Al2O3-SiO粉料,并通过二步加热处理工艺制备自生晶须莫来石材料。研究结果表明,凝胶胶化时间、干凝胶预烧温度和粉料粒度以及生坯密度对自生晶须有重要影响,自生晶须对莫来石材料有明显的强韧化作用。     

Technique for Producing Mullite and Other Mixed-Oxide Systems

Mixed-oxide systems are of interest in a variety of technical ceramic applications. The key in many systems is to achieve a high degree of homogeneity, approaching the molecular level. A technique for producing mixed oxides via direct oxidation of mixtures of organometallic compounds is discussed as a potential route. Preliminary work performed on producing mullite is discussed.     

Anisotropic Grain Growth and Microstructural Evolution of Dense Mullite above 1550°C

Mullite powder with a nearly stoichiometric composition was hot-pressed at 1550°C to produce an almost fully dense microstructure of fine, nearly uniaxial grains. The grain growth of the dense mullite was investigated during subsequent annealing at temperatures in the range of 1550–1750°C. Grain growth was relatively slow at 1550°C and the microstructure remained nearly equiaxial. Annealing at temperatures above the eutectic temperature (∼1590°C) produced fairly rapid anisotropic grain growth. At 1750°C, the anisotropic grain growth can be divided into two stages. In the first stage, the initial microstructure with an anisometric shape factor of 1.7 evolved rapidly into a microstructure with a shape factor of 2.7, consisting of a significant fraction of highly elongated grains. In the second stage, the microstructure evolved slowly into a system consisting of somewhat blocky grains with a shape factor of 2.2. The Al₂O₃ content of the mullite grains increased slightly and reached an equilibrium value during the first stage of anisotropic grain growth. For the samples annealed at 1750°C, the indentation fracture toughness (2.5 ± 0.2 MPa · m^1/2) was almost independent of the anisometric shape factor. The interaction between the indentation cracks and the microstructure showed a predominantly transgranular mode of crack propagation. The data indicate that while a network of highly elongated grains can be developed by the present approach, some further manipulation of the grain boundary chemistry is required for an improvement of the fracture toughness.     

部分莫来石化陶瓷催化剂载体的研究

高温燃烧催化荆需要在高于1000℃的氧化气氛中，具有良好的耐热性、抗热冲击性和较大的比表面积。国内使用的催化荆仅能烧至600℃，高于600℃活性就会下降，甚至失活。本文探讨的部分莫来石化陶瓷催化荆载体，不但耐热性好，而且催化活性高，具有良好的使用前景。     

酸碱条件下莫来石形成机理研究

以正硅酸乙酯(C8H20O4Si),硝酸铝(Al(NO3)3·9H2O)为主要原料,氨水调节pH值,通过溶胶凝胶法制备出酸碱条件下纯相莫来石粉体.通过热分析得知粉体在升温过程中吸热、放热和晶相转换过程;通过XRD研究了凝胶在热处理过程中的结晶变化;通过红外吸收光谱测定了粉体中Si-O-Al键的存在和变化;通过环境扫描电子显微镜测定研究了莫来石粉末的表面特性.最终得出凝胶转变至莫来石的相变过程:酸碱条件下莫来石的生成过程都经历了由无定形铝和无定形硅转变为硅铝尖晶石再到莫来石的过程;在碱性条件下,莫来石开始转变温度低于酸性;同时生成的莫来石中,碱性条件比酸性条件粒度小.     

Synthesis of Submicrometer Mullite Powder via High-Temperature Aerosol Decomposition

High-purity mullite powders (3Al₂O₃.2SiO₂) have been prepared using a high-temperature aerosol decomposition technique yielding submicrometer (0.6 μm average) particles of spherical morphology with no hard agglomerates using aluminum nitrate and fumed silica as precursors. Depending upon the reaction conditions used, the powders range from amorphous to crystalline with no evidence of secondary-phase formation. This mullite synthesis approach has the advantages of not requiring postsynthesis milling, the ability to use a wide range of precursor systems, and enhanced control over chemical homogeneity and particle size/shape.     

Svnthesis and Characterization of Nanoscale Mullite Powder

Nanoscale mullite powder were synthesized via Solgel-SCFD and middle temperature treatment by using AIP( aluminum-isopropoxde ) and TEOS ( tetraethyl orthosdicate) as starting materials. Both of the binary aerogel of alumina-silica and calcined nanoscale materials were investigated by using TG-DSC (thermogravimetry-differential scanning calorimeter), TEM (transmission electron microscope), XRD ( X-Ray diffractometer ) and specific surface area and porosimetry. TG-DSC indicated the removal of most of the volatiles , i. e. 15.98% up to about 700℃ ,and in the DSC curve, existence of two exothermic peak at about 445℃ and 1015℃ may be due to the crystallization of Si-O-Al-O in diphasic gels and mullitization and a small endothermic peak at about 805℃ indicated the decomposition of structural water molecules. On the colligation of the results of TG- DSC, XRD and TEM , the beginning temperature of mullitization in Al2 O3-SiO2 aerogel system can be confirmed at about 1015℃. XRD results also showed the formation of mullite at the range 1100 ～1200℃. TEM and surface area and porosimetry results showed that the nanosized mullite were calcinated at 1100and 1200℃ exhibited size 30nm and 50nm, specific surface area 138.91m2/g and 95.81m2/g.