基于激光热成像技术的耐火材料导热系数测试新方法

为了满足耐火材料对导热系数测试快速、准确的需求,提出了基于激光加热耐火材料、结合红外热成像技术的材料导热系数测试新方法——激光热成像法,并与现有国家标准的闪光法测试导热系数常用的耐驰公司激光导热仪FLASHLINE-500进行数据对比,探讨了两种不同方法测试不同成分耐火材料导热系数的差异。结果表明:相比闪光法,采用激光热效应结合红外热成像技术的新测试方法能快速、准确地测量出不同耐火材料的导热系数;对材料的导热情况显示直观、明确,测试方法操作简单,抗干扰能力强,大大降低了测试的成本投入。     

耐火材料导热系数的检验方法

分析不同的耐火材料导热系数试验方法,介绍其试验原理、样品尺寸、温度范围等方面的内容,为最终能够在耐火材料导热系数检验过程中,选择适合的导热系数测定方法提供了借鉴,并且提出了当前导热系数测定过程中急需解决的问题。     

节能型低导热性内衬耐火材料

为了有效地控制工业窑炉在间歇式操作时的热能损失,降低内衬材料的热容量和导热系数非常重要。开发了低导热性内衬耐火材料,使导热系数降低约30%。新开发的耐火材料在100t的LF炉中应用证实LF处理时间缩短10%、LF耗电量降低8%。在185t钢包中使用,获得了大幅度抑制钢水温度降低的效果。     

问：目前国内推板窑使用的推板大多采用碳化硅质的。请问碳化硅质耐火材料的优点是什么？现今已开发出了哪些优良品种？它们的性能怎样？

答：碳化硅耐火材料具有强度高、导热系数大、抗热震性好、抗氧化、耐磨损、抗侵蚀等优良的高温性能，是一种优质、低成本的耐火材料，已在陶瓷、化工、冶金、能源等行业得到广泛应用。     

工业窑炉新型耐火材料热物理性能的研究

选择常用的耐火材料,模拟工业窑炉(主要是陶瓷窑炉)实际工况的温度分布特点,在各种温度下对材料试样进行导热系数的测试,最后利用数学方法对测试数据进行分析整理,得出与温度的关系表达式或图表。     

粉煤灰类保温材料的导热系数

粉煤灰类保温材料的导热系数表示墙体材料保温隔热性能的主要指标是导热系数，对其进行测试需要专用的设备技术，目前国内许多试验室不具备这样的条件。材料导热系数与其容重有关：容重越大，导热系数越高；容重越小．导热系数越低。笔者收集了《粉煤灰综合利用》等书刊发...     

激光闪射法测量耐火材料的热物理性能

介绍了应用激光闪射法测量耐火材料比热容、热扩散系数以及导热系数等热物理性能的原理,列举应用实例说明了测试方法,并且讨论了影响实验数据准确性的因素。     

PE-XC材料导热系数的测量

文章采用瞬态热线法测试PE材料的导热系数,介绍了瞬态热线法的优势,并使用TC3000导热系数仪更加快捷、精确、高效的测试PE材料的导热系数。     

导热系数测试方法的综述

本文介绍了导热系数的五种测试方法,描述各种方法的测试原理及其计算方法。材料导热系数测试方法各有其特点,在选择时。应该充分考虑测试材料的性质、导热系数范围、测试温度等。     

高温用高性能隔热浇注料

日本品川耐火材料公司新开发了LN-150和LA-150-2两种高温用隔热浇注料。LN-150具有与常规产品LA-155相同的低导热系数,还具有普通浇注料的高强度。LA-150-2既保留了相同常规浇注料LA-155的强度,又降低了体积密度和导热系数。     

含油气盆地中热传导与岩石热导率研究

含油气盆地中热传导是最主要的热量传递方式,在大地热流一定的情况下制约热传导的主要因素是热导率的大小。前人对岩石热导率与温度、压力、岩石孔隙度的关系以及岩石热导率的各向异性进行了研究。本文对前人的研究成果进行了综合分析,认为下一步应该加强沉积岩平行层面方向和垂直层面方向热导率差异的研究及热导率与岩石输导性能关系的研究。     

Effect of Crystallization on Thermal Conductivity and Specific Heat of Two Corning Glass-Ceramics

A magnesium aluminosilicate glass-ceramic (Corning Code 9606) has been heat-treated at 900°, 1010°, 1200°, and 1260°C for up to 90 min., and the effect on the thermal conductivity between 30 and 300 K has been studied. It has been shown that the large increase of the thermal conductivity which results from the ceramming occurs predominantly when crystalline cordierite forms. At 1260°C, heat treatment for only 20 min leads to a thermal conductivity identical to that measured for commercial 9606, which has been cerammed for 8 h at the same temperature. This observation provides further evidence for the usefulness of commercial 9606 as a thermal conductivity standard. Measurements of the specific heats of Code 9606 before and after ceramming have been reviewed and have been found to be close to that of crystalline SiO₂ above ∼ 30 K, regardless of the state of ceramming. A review has also been made of thermal conductivity and specific heat of several ZrTiO₄ nucleated lithium aluminosilicate glass-ceramics at various states of ceramming. The thermal conductivity of these glass-ceramics seems to be sufficiently independent of chemical composition as well as of the degree of crystallization to warrant a recommended curve for this class of glass-ceramics.     

Phonon engineering in tuning the thermal conductivity of alkaline-earth hexaborides

Controlling the thermal conductivity of alkaline-earth hexaborides is of great importance for their applications as thermoelectric materials and ultrahigh temperature thermal insulation materials. However, no consensus has been reached on intrinsic κ, and the mechanism behind thermal reduction due to metal element incorporation is still blurry. In this work, the intrinsic thermal conductivity of three alkaline-earth hexaborides has been investigated theoretically. The simulated thermal conductivity of three borides shows good agreement with experiments. By examining mode contributions to total thermal conductivity, important role of low-lying optical modes in shaping the thermal transport property of hexaborides through controlling the interaction between acoustic and optical modes is uncovered. Our results demonstrated that tuning the thermal conductivity relies on shortening of mean free path of contributive phonon either by grain boundary scattering or by phonon-phonon interaction. The choice criterion on the doping atom to efficiently decrease thermal conductivity of alkaline-earth hexaborides is proposed.     

二维氮化铝材料传热性能的模拟研究

二维氮化铝材料是一种新型Ⅲ-Ⅴ族二维材料,具有与石墨烯相似的分子结构和材料性能,受到了广泛的关注,然而其导热性能尚未被充分探讨。应用分子动力学模拟的方法研究了单层二维氮化铝在不同温度的热稳定性和导热性能,并分析了其声子频谱。结果表明,单层二维氮化铝材料可以在极高温度（3500 K）下保持结构稳定性,同时在常温情况热导率可达264.2 W·m^-1·K^-1;在500 K以上温度时,声子色散现象使得该材料热导率明显降低。为二维氮化铝材料导热过程的调控和高温导热材料的应用提供了理论指导。     

Behaviour of gas-fluidized beds of fine powders part III. Effective thermal conductivity of a homogeneously expanded bed

The effective thermal conductivity of the dense phase in expanded non-bubbling fluidized beds has been studied between minimum fluidization and minimum bubbling for 9 gas—solid systems. Except close to minimum bubbling, the effective thermal conductivity is not a function of bed voidage and is most sensitive to the gas phase thermal conductivity. The experimental results have been compared with 11 packed bed correlations and with suitable modification three of these can be used to accurately predict the effective thermal conductivity of a non-bubbling fluidized bed.     

The dependence of thermal conductivity of binder residues on heat treatment temperature

The dependence of the thermal conductivity of carbon residues of one pitch and one polyfurfuryl alcohol binder on the heat treatment temperature has been investigated. Specially prepared graphites made with these two binders were used for the experiments. The thermal conductivity data were analyzed in terms of a two-component system and the binder residue thermal conductivity calculated. Both binder residues show an increase in thermal conductivity with increasing heat treatment temperature.     

耐硫甲烷化催化剂的有效导热系数研究

在常压空气气氛下采用稳态法测试了KD306型耐硫甲烷化催化剂的有效导热系数,运用Woodside随机模型,建立了反应状态下有效导热系数的计算模型。研究表明,该催化剂有效导热系数较大,温度、压力影响明显,组成影响较小。     

Measurement of thermal conductivity of epoxy resins during cure

This work reports the development of a methodology for the measurement of thermal conductivity of thermosetting polymers during their cure. The study addresses the reliability and robustness of the method through FEA modeling and testing using a noncuring material with known thermal conductivity. The thermal conductivity and its evolution during the cure has been measured for three widely used aerospace epoxy resins, namely, RTM6, 890RTM, and the XU3508/XB3473 system as function of cure temperature. A constitutive model expressing the dependence of thermal conductivity on the degree of cure and temperature has been established. The device developed here can measure thermal conductivity of epoxy resin with accuracy up to 3%. © 2018 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47015.     

热塑性聚酰亚胺复合材料导热性能研究

采用稳态热板法测定铜粉（Cu）填充热塑性聚酰亚胺（TPI）复合材料的热导率，研究了Cu填充量对复合材料的力学性能和导热性能的影响，初步探讨了温度与复合材料热导率的关系。通过扫描电子显微镜观察了复合材料的微观形态。在此基础上，理论计算复合材料热导率。研究表明，Cu填充TPI可有效提高复合材料力学性能和导热性能。当Cu体积分数提高到26％时，填料聚集形成导热链，Cu／TPI复合材料的热导率是纯TPI树脂的3．5倍；当填料含量低于10％时，Maxwell—Eucken模型适合预测复合材料热导率；基于导热链考虑的Y．Agan模型可较好地反映复合材料热导率随填料含量的变化情况；随着温度的升高，Cu／TPI复合材料热导率先增大后趋于平缓。     

Thermal conductivity and viscosity measurements of ethylene glycol-based Al<Subscript>2</Subscript>O<Subscript>3</Subscript> nanofluids

The dispersion and stability of nanofluids obtained by dispersing Al₂O₃ nanoparticles in ethylene glycol have been analyzed at several concentrations up to 25% in mass fraction. The thermal conductivity and viscosity were experimentally determined at temperatures ranging from 283.15 K to 323.15 K using an apparatus based on the hot-wire method and a rotational viscometer, respectively. It has been found that both thermal conductivity and viscosity increase with the concentration of nanoparticles, whereas when the temperature increases the viscosity diminishes and the thermal conductivity rises. Measured enhancements on thermal conductivity (up to 19%) compare well with literature values when available. New viscosity experimental data yield values more than twice larger than the base fluid. The influence of particle size on viscosity has been also studied, finding large differences that must be taken into account for any practical application. These experimental results were compared with some theoretical models, as those of Maxwell-Hamilton and Crosser for thermal conductivity and Krieger and Dougherty for viscosity.