共查询到18条相似文献,搜索用时 78 毫秒
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炭黑对轮胎胎面胶热物性的影响 总被引:1,自引:0,他引:1
研究了炭黑品种和用量对轮胎胎面胶热扩散系数(α)、导热系数(λ)及比热容(C)3种热物性参数的影响规律。结果表明,随着炭黑填充量的增加,胎面胶的α及λ均逐渐增大,C逐渐减小。炭黑的结构性对胎面胶α的影响程度大于炭黑的粒径;温度相同时,炭黑的结构性越高,其填充胎面胶的α越大;随着炭黑填充量的增加,3种炭黑填充胎面胶α之间的差距呈现先增大后减小的变化趋势。炭黑的结构性及粒径对胎面胶C的影响没有固定的规律,但在低温区,炭黑的粒径越大,其填充胎面胶的C越大,且炭黑填充量对此差距无影响。炭黑的结构性对胎面胶λ的影响程度大于炭黑的粒径;温度相同时,炭黑的结构性越高,其填充胎面胶的λ越大;当炭黑用量较低时,其对胎面胶λ的影响程度相对较小,随着炭黑填充量的增加,3种炭黑填充胎面胶λ之间的差距呈现先增大后减小的变化趋势。 相似文献
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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。 相似文献
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耐火材料力学—热物理性能的评述 总被引:4,自引:0,他引:4
本文简述了对耐火材料机械性能及热震稳定性的已有知识及有关研究的进展。讨论了耐火材料化学成份,相组成,微观及宏观组织对其弹性常数、力学强度、断裂及热震参数等物理化学性能的影响;探讨了耐火材料现有测试评价技术中的问题和未来研究的方向。 相似文献
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E. Zapata-Solvas D.D. Jayaseelan P.M. Brown W.E. Lee 《Journal of the European Ceramic Society》2013,33(15-16):3467-3472
Thermal properties of La2O3-doped ZrB2- and HfB2-based ultra high temperature ceramics (UHTCs) have been measured at temperatures from room temperature to 2000 °C and compared with SiC-doped ZrB2- and HfB2-based UHTCs and monolithic ZrB2 and HfB2. Thermal conductivities of La2O3-doped UHTCs remain constant around 55–60 W/mK from 1500 °C to 1900 °C while SiC-doped UHTCs showed a trend to decreasing values over this range. 相似文献
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实验探讨了试样轴径向比热容测试的差异性,获取了最佳测试方向,并在此基础上进一步研究了试样厚度对热损影响的程度,获得了最佳厚度值范围。结果表明,采用激光脉冲法进行比热容测试过程中,C/C复合材料内部传热非常复杂,具有非一维传热的特点,但在一定的试样条件下可以获得较好的测试效果;比热容测试时试样应选择热损小的方向,即毡基和轴编材料均应取纤维质量分数高且分布均匀的径向。 相似文献
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Microstructure and thermo-physical properties of yttria stabilized zirconia coatings with CMAS deposits 总被引:4,自引:0,他引:4
Jing WuHong-bo Guo Yu-zhi GaoSheng-kai Gong 《Journal of the European Ceramic Society》2011,31(10):1881-1888
Yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) are used to protect hot-components in aero-engines from hot gases. In this paper, the microstructure and thermo-physical and mechanical properties of plasma sprayed YSZ coatings under the condition of calcium-magnesium-alumina-silicate (CMAS) deposits were investigated. Si and Ca in the CMAS rapidly penetrated the coating at 1250 °C and accelerated sintering of the coating. At the interface between the CMAS and YSZ coating, the YSZ coating was partially dissolved in the CMAS, inducing the phase transformation from tetragonal phase to monoclinic phase. Also, the porosity of the coating was reduced from ∼25% to 5%. As a result, the thermal diffusivity at 1200 °C increased from 0.3 mm2/s to 0.7 mm2/s, suggesting a significant degradation in the thermal barrier effect. Also, the coating showed a ∼40% increase in the microhardness. The degradation mechanism of TBC induced by CMAS was discussed. 相似文献
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《Journal of the European Ceramic Society》2022,42(5):1877-1883
High thermal conductivity, wear resistant graphite is desirable for a range of applications, for example as an electrode to minimize energy consumption in aluminium smelting. This paper demonstrates that by infiltrating the porosity by reactive infiltration with SiC at levels ranging from 4 to 12 vol.% or Si3N4 ranging from 7 to 19 vol.% the thermal conductivity can be raised progressively from ~41 W/m K to ~53 and 64 W/m K respectively. A simple analytical model predicts thermal conductivity rises with increasing reinforcement fraction only 7–9 % higher than that observed. This suggests that heat transfer between the graphite and the reinforcing particles is good making these materials good options where improved thermal conductivity and wear resistance over graphite is required. 相似文献
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《Ceramics International》2017,43(6):4731-4745
Thermal conductivity (k) is one of the most important properties in the design and optimization of refractory linings, as well as for defining safe heating and cooling schedules. Mathematical models for predicting refractories’ thermal conductivity have been proposed in the literature but, in general, they were simplified equations focusing on correlating k with density, alumina content or temperature. This work addresses the development of general expressions for k predictions as a function of physical (density, porosity) and chemical (oxide content) parameters with the temperature for Al2O3-SiO2 and Al2O3-CaO-based refractories. The parallel hot wire technique was used to measure the thermal conductivity of insulating, dense and low-cement-containing (LCC) commercial products in the temperature range of 25 °C to 1000 °C. According to the results, the most suitable mathematical model correlating k with the samples’ density (apparent, volumetric or geometric) and temperature was the geometric one (r2=97.1%). When considering multi-linear models and the combination of more parameters (oxide content, density, temperature), lower r2 values were obtained (74.1–75.5%), indicating that this more complex and all-inclusive expression should lead to a less accurate prediction of thermal conductivity values. The advances presented will be a helpful tool for refractory producers and end-users. 相似文献
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Sonia N. Vijayan Mahak Vij Kanika Thukral Naghma Khan D. Haranath Rajnikant M. S. Jayalakshmy 《中国化学工程学报》2019,27(3):701-708
In the contemporary days, non-linear optical materials(NLO) are getting higher attention as per the increasing demand in optical communication and data storage technology. Consequently, they explore various physical properties of the NLO material for their industrial applications. In current report, l-arginine p-nitrobenzoate monohydrate(LANB) single crystals were obtained by adopting slow cooling technique. The structural confirmation of grown single crystal was carried out using single crystal X-Ray diffractometer. Presence of strain within single crystal was deduced using Hall–Williamson relation. Various defects associated within single crystal were assessed using high resolution XRD. Additionally, its crystalline quality was again confirmed by time resolved photoluminescence spectroscopy(TRPL). Using transmission spectra, the cut off wavelength and band gap of the host material was determined to be nearly 420 nm and 2.9 e V respectively. The dielectric property has been recorded by varying the frequency ranging from 50 Hz to 100 k Hz. The curve suggests that dielectric loss value is less at high frequency ensures the suitability of crystal in photonics and NLO based devices.The laser damage threshold values were also measured for single and multiple shots. Thermal parameters of the titled compound were calculated using PPE. In photoconductivity measurement, negative photoconductivity has been observed in titled compound. Microhardness studies were also performed on single crystal to explore its mechanical properties. 相似文献
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Unidirectional carbon/carbon composites were developed using high-pressure impregnation/carbonization technique with PAN and pitch based carbon fibers of varying microstructure as reinforcements and different types of pitches as matrix precursors. The composites have been given final heat treatment to 2500-2700 °C. Microstructure of these composites has been evaluated using scanning electron microscope and polarized light optical microscope. Thermophysical properties, i.e., thermal conductivity, coefficient of thermal expansion and specific heat have been evaluated. It is found that the type of fibers and matrix present in the composites influences the absorption (specific heat) and transmission (conductivity) of thermal energy. The temperature dependence of thermal diffusion, specific heat, thermal conductivity and coefficient of thermal expansion has been studied and correlated with microstructure of carbon/carbon composites. 相似文献