球土含量对环保型轻质材料性能的影响

本文以陶瓷抛光废料为主要原料,辅以球土、长石、石英等,制备一种以闭口气孔为主的新型轻质建筑材料.在此基础上,采用XRD、体式显微镜、导热仪等研究了球土含量对试样的体积密度、抗压强度、物相组成、导热系数等性能的影响.实验结果表明:随着球土含量的增多,材料中莫来石相开始形成并逐渐增多,抗压强度也逐渐增强;另一方面,随着球土添加量的增加,试样中孔径明显变小,体积密度增大,相应的导热系数随体积密度的增大而直线增大.     

堇青石加入方式对堇青石-莫来石窑具材料性能的影响

为满足锂离子电池正极材料烧成的需要,以堇青石、莫来石、高岭土和氧化铝为原料制备堇青石-莫来石窑具材料,研究了堇青石颗粒和细粉加入量对堇青石-莫来石窑具材料的常温性能、高温抗折强度和抗热震性的影响.并用XRD和SEM分析了试样烧后的物相变化与显微结构.结果表明:随着堇青石颗粒或细粉加入量从0到30％(质量分数),试样的线变化率、显气孔率、高温抗折强度增大,体积密度下降;而对常温抗折强度的影响不大,试样的耐压强度分别呈现下降或提高的趋势,试样的抗热震性先增加后降低,当堇青石颗粒含量为20％,细粉含量为20％时,试样的抗热震性最好.     

氧化铬对菱镁矿风化石制备堇青石材料的影响

本研究以辽南地区菱镁矿风化石、工业氧化铝、二氧化硅微粉为原料制备堇青石材料,研究分析氧化铬对制备堇青石材料中晶相、晶胞参数、晶相含量及显微结构的影响.用XRD和SEM表征各试样中的晶相和显微结构;用X' Pert Plus软件对晶相的晶胞参数和晶相含量进行分析.结果表明:以菱镁矿风化石为原料经过1350℃烧成可以制备出以堇青石为主晶相的堇青石材料.氧化铬与堇青石形成有限的固溶体,当氧化铬加入量为0.8％时,堇青石晶格常数及晶胞体积都最大;小于1.2％的氧化铬的加入会降低了系统中晶相的含量,当氧化铬加入量大于1.2％时,系统中晶相的含量随着氧化铬加入量的增加而逐渐增大.     

水泥-铁尾矿泡沫混凝土的性能研究

研究了铁尾矿掺量对水泥-铁尾矿泡沫混凝土的干体积密度和抗压强度的影响,以及孔结构对泡沫混凝土导热系数的影响.测试了泡沫混凝土的导热系数,用显微镜和图像分析软件分析了泡沫混凝土的气孔结构,建立泡沫混凝土的抗压强度与干体积密度的关系模型,分析导热系数随孔结构的变化规律.结果表明铁尾矿取代水泥后泡沫混凝土的抗压强度降低,且其影响程度随混凝土气孔率的增大而减小.泡沫混凝土的抗压强度与干体积密度呈对数关系,与铁尾矿掺量成指数关系.泡沫混凝土密度相同时,气孔孔径越大抗压强度越高.随着气孔孔径的增大,泡沫混凝土的导热系数逐渐增大;随着孔隙率的增大,泡沫混凝土的导热系数逐渐减小;当孔隙率一定时,气孔孔径越小导热系数越小.     

堇青石对莫来石-铝矾土浇注料性能的影响

以莫来石、铝矾土为主要原料,铝酸钙水泥为结合系统,分别研究了不同堇青石含量经过不同热处理温度后对莫来石-铝矾土浇注料性能的影响.试样自然干燥24 h脱模后,再经110 ℃烘干24 h,分别于1000 ℃、1300 ℃和1500 ℃热处理3 h.检测各温度热处理后试样的线变化率(P.L.C)、体积密度(B.D)、抗折强度(M.O.R)、耐压强度(C.C.S)以及试样的热膨胀系数和抗热震性能.结果表明,莫来石-铝矾土浇注料的体积密度随着堇青石含量的增加而减小.经过1000 ℃和1300 ℃热处理后,莫来石-铝矾土浇注料的抗折强度随着堇青石含量的增加而下降.莫来石-铝矾土浇注料随着堇青石含量的增加,有助于改善材料的抗热震性,材料的强度保持率逐渐增大,且较低的体积密度有利于材料获得较高的热震后的强度保持率.     

掺稻壳灰泡沫混凝土的制备与性能研究

以稻壳灰作为掺合料制备了掺稻壳灰的泡沫混凝土,研究了稻壳灰含量和泡沫体积占比对泡沫混凝土干密度、湿密度、吸水率、抗压强度和导热系数的影响.结果 表明,当稻壳灰含量为0％和10％时,水泥泡沫混凝土和碱激发泡沫混凝土的干密度、湿密度、7d和28 d抗压强度、导热系数都随着泡沫体积比增大而逐渐减小,而吸水率则随着泡沫体积比增大而逐渐增加.相较于水泥泡沫混凝土,相同稻壳灰含量和泡沫体积占比的碱激发泡沫混凝土的干密度、湿密度、吸水率和导热系数都相对更小,抗压强度更大.无论稻壳灰含量为0％还是10％,水泥泡沫混凝土的导热系数都不满足规范标准要求,而碱激发泡沫混凝土的导热系数都满足规范标准要求.     

黏土的杂质含量对堇青石-莫来石复合材料相组成及性能的影响

以滑石细粉、高铝矾土细粉和两种不同杂质含量的黏土细粉为原料,经配料、加水混练成型后,分别于1300、1350和1400℃保温3h制备了堇青石-莫来石复合材料的试样,用XRD、SEM等研究了黏土中杂质含量对堇青石-莫来石复合材料相组成及性能的影响。结果表明:1)使用高杂质含量的黏土能有效降低试样的烧结温度,促进堇青石和莫来石晶体的生成发育,提高试样的体积密度与常温抗折强度,但对其抗热震性损害较大。2)使用高杂质含量的黏土时,提高MgO含量虽然可增加堇青石的含量,但玻璃相含量增加且黏度降低,不能有效提高材料的抗热震性;而使用低杂质含量的黏土时,通过控制引入MgO的含量与煅烧温度,可调节试样中晶相的含量与组成,从而可提高材料的抗热震性。     

添加Li2CO3和BaCO3对合成堇青石性能的影响

采用煤系高岭土、滑石和镁砂为主要原料,在化学组成(w)为MgO13.23%,Al2O333.78%,SiO251.16%的研究配方(试样A)的基础上,分别添加1.0%、1.5%、2.0%的Li2CO3(对应试样编号为L1、L2、L3)或1.0%、2.0%、3.0%的BaCO3(对应试样编号为B1、B2、B3),以100MPa压制成36mm×50mm的圆柱状试样,在110℃干燥4h后,以3~5℃·min-1的升温速度升至1340℃保温3h烧成,然后检测试样的烧后体积收缩率及体积密度、显气孔率和热膨胀系数,并采用XRD分析矿物成分,K值法测量烧后试样的堇青石相含量,以探讨添加Li2CO3和BaCO3对合成堇青石性能的影响。结果表明:随着Li2CO3添加量的增加,烧后试样的体积收缩率和体积密度逐渐增大,显气孔率逐渐减小,而添加BaCO3对堇青石合成过程中的烧结性影响不大;烧后试样A和B2中除分别含有为90%和95%的堇青石外未检测到其他晶相,但L1中还存在一定量的LiAlSi2O6相;添加剂Li2CO3或BaCO3均能降低合成堇青石的热膨胀系数。     

堇青石的低温合成与表征

堇青石具有很多优异的性能,被广泛应用于耐火材料,红外辐射陶瓷及计算机集成电路基片等。天然矿物中的堇青石含量很少,且收集需要的难度高,很难在工业上广泛应用,人工合成堇青石成了堇青石原料的主要来源。本实验采用高温固相法、用"滑石-高岭土-氧化铝"系统进行堇青石制备,以钾长石代替氧化铝,在1200℃的温度下合成出了堇青石。当钾长石掺量为15%的时候,所得到的堇青石样品具有最好的性能,除了有较高的红外发射率,抗压强度达到了110MPa外,所生成的堇青石的量最多,孔隙率较小。     

碳铬渣合成堇青石的反应机理及结构表征

以高碳铬铁合金渣、工业氧化铝粉和硅微粉为主要原料,通过高温固相法合成制备堇青石。利用X射线衍射和扫描电子显微镜等研究了烧成温度、保温时间对堇青石材料结晶度、晶粒尺寸、晶相组成和显微结构的影响规律。结果表明:样品中堇青石主要由镁橄榄石进一步反应生成,其最佳烧结制度为1 350℃,保温3 h,堇青石含量在87%左右;随着烧结温度和保温时间升高,样品相对结晶度降低,堇青石晶粒尺寸则逐渐增加,晶胞参数沿a轴晶向轴方向增大,c轴方向减小,晶胞体积变大。铬元素固溶进堇青石晶格是使其晶胞参数变化的主要原因。     

高炉炭砖的导热系数及其影响因素

对微孔、半石墨质和普通等级炭砖试样的导热系数与温度的关系做了回归分析,得到了导热系数和温度的关系表达式,由此,可以从室温导热系数预测高温导热系数。另外,还计算了导热系数与体积密度、显气孔率、透气度和原料等级之间的相关系数。结果表明,导热系数与透气度和原料等级有一定的相关关系,而与体积密度和显气孔率无关。     

Effects of pitch fluoride on the thermal conductivity of carbon foam derived from mesophase pitch

Carbon foams with high thermal conductivity were obtained from mixtures of mesophase pitch and pitch fluoride. The addition of pitch fluoride in mesophase pitch could significantly increase the specific thermal conductivity of as-prepared carbon foams. After graphitization at 2873 K, the specific thermal conductivity of carbon foams increased from 82 up to 155.4 (W/mK)/(g/cm³) when the content of pitch fluoride was 3% in the raw material.     

Study of the thermal characteristics of phosphate raw materials in the annealing temperature range

In this paper, the thermal characteristics of phosphate raw materials have been studied, including thermal conductivity and volumetric heat capacity in the temperature range that has practical significance in the chemical and technological system of thermal preparation of raw materials. The method of the regular regime of the third kind and the method for solving the inverse heat-conduction problem have been used based on the joint solution of the equations of heat transfer and the kinetics of chemical reactions taking into account the most important accompanying phenomena. A dilatometric analysis of the studied samples of phosphate raw material has been presented.     

Calculation of the properties of raw briquet for producing foam glass in the temperature range of preheating

The suggested method allows for the calculation of a temperature dependence of the density, thermal conductivity, and specific thermal capacity of a raw briquet (from glass powder) during preheating in the course of foam glass production. The properties of the raw briquet were determined based on the structure and chemical composition of the raw material (glass). The resulting dependences can be used to solve the problems of heat-mass exchange.     

Thermal insulation characteristics of roll forming alumina ball material

Rolling ceramic thermal insulation balls have advantages of low cost, large output and easy control of particle size, so it is likely to become the main raw material for 3D printing in the future, but there is little research on its thermal insulation. In this study, we used three kinds of rolling aluminum oxide balls as raw materials to obtain single-granularity-level and multi-granularity-level bulk materials. And the effects of temperature, particle size, and thermal fatigue times on the thermal conductivity of the samples were analyzed. Additionally, the experimental results were verified by FloEFD heat conduction simulation software using finite analysis method to analyze their heat conduction characteristics. With the increase of temperature from 400 °C to 1500 °C, the thermal conductivity of single-granularity-level and multi-granularity-level bulk materials increased linearly. The thermal conductivity of single-granularity-level bulk materials have no direct relationship with the particle size, and the thermal conductivity of multi-granularity-level materials with small particle size difference was a bit lower than that of materials with large particle size difference, and a bit higher than that of materials with single-granularity-level. The simulation results showed that the main reason for the above phenomenon was that the point contact between particles played a dominating role in the heat transfer process. When the contact area increased, the thermal conductivity increased obviously, and the thermal conductivity with the increasing of temperature decreased in a quadratic curve. The improved model considering the shrinkage could improve accuracy of simulation results. Heat flux at the surface contact area was 10.19 times higher than that of the point contact and 15.10 times higher than that of the solid-gas contact at 400 °C. Therefore, reducing the surface contact area and increasing the porosity could significantly reduce the thermal conductivity of the materials.     

Evaluation of remelting low-fluxing ferrotitanium slag as a potential refractory raw material: Thermal characteristics and stability

To effectively promote the utilization of metallurgical waste slag, studies on the characteristics and stability of waste slag are essential for waste reuse. Ferrotitanium slag is a byproduct of smelting ferrotitanium with thermite reduction. Low-fluxing ferrotitanium slag (LFS) is the main type of dumping slags produced by ferrotitanium smelting. In this study, an electric arc furnace was used to prepare remelting LFS (RLFS) for homogenization and impurity removal. The characteristics and thermal stability of RLFS as a refractory raw material were characterized. The thermal stability of RLFS was tested under different working conditions. A phase-structure transition mechanism of RLFS particles was established according to the thermal stability test and thermodynamic calculations. The Al₂O₃ content in RLFS exceeded 80%, and RLFS had lower thermal conductivity than brown corundum, but a similar thermal expansion coefficient. The results show that RLFS is a suitable substitute for corundum raw material; the thermal stability test results show that RLFS was susceptible to crack propagation in an oxidizing environment above 1280 °C. The findings of this research provide suggestions for the utilization of RLFS to improve the application stability of refractory products using recycled raw materials.     

烧成工艺对花岗岩基轻质隔热材料性能的影响

以花岗岩废料、黏土、长石为主要原料制备了花岗岩基轻质隔热材料。研究了不同烧成工艺制度(烧成温度、保温时间、升温速率)对该隔热材料性能的影响,确定最优烧成制度,制备出表观密度小、抗压强度高、常温导热系数小的高性能隔热材料。结果表明,以5 ℃/min从常温升至1 000 ℃,再以3 ℃/min升至1 200 ℃并保温30 min,在此烧成工艺制度下制备的隔热材料试样的表观密度为0.6 g/cm³,常温抗压强度18.11 MPa,常温导热系数为0.2 W/(m·K),综合性能最好。     

Synthesis and characterization of calcium silicate insulating material using avian eggshell waste

This work focuses on the synthesis of calcium silicate insulating material via solid state reaction using avian eggshell waste as alternative calcium source. The calcium silicate formulations were mixed in a molar ratio SiO₂:CaO (1:1) and fired at 1100 °C for 24 h. The calcium silicate formulations were characterized by XRD, TG-DTA, dilatometry, SEM/EDS, and thermophysical properties (thermal diffusivity, heat capacity per unit volume, and thermal conductivity). The synthesized calcium silicate materials are composed mainly of wollastonite with minor amounts of larnite and rankinite. It was found that a processing of the avian eggshell waste (raw eggshell waste and calcined eggshell waste) had an influence on the thermophysical properties. Calcium silicate pieces were prepared by uniaxial pressing at 82 MPa, curing, and then testing to determine their use as thermal insulating material. The microstructure was evaluated by SEM. The results showed that both raw and calcined avian eggshell wastes could be used as an alternative calcium source in the calcium silicate formulation. It was found that the calcium silicate pieces reached low thermal conductivity values (0.252–0.293 W/mK). Thus, the developed calcium silicate materials using avian eggshell waste act as a good thermal insulation ceramic material.     

氧氮化硅结合碳化硅制品的生产与使用

以工业用黑色碳化硅砂、硅粉为主要原料，研制出了导热性能优良、抗热震性好、耐高温、耐侵蚀及耐磨损，且生产工艺较简单、成本较低的氧氮化硅结合的碳化硅制品．该产品已广泛应用于冶金炉、化工设备及发电用锅炉的内衬，并取得了较满意的效果。