共查询到19条相似文献,搜索用时 437 毫秒
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符号表A无量纲温度幅值L。热扩散长度。1二维效应作用区边界AD温度幅值。试样表面法向Yd样品无量纲厚度AO特征温度q热源热流。材料热扩散率C材料体积比热容qb热源热流幅值。”测量热扩散率d样品厚度T试样上某点温度A材料导热系数h表面等效换热系数几边界温度p温度相位He无量纲换热系数。。光源边界。测量角频率1前言使用周期热流法测量薄膜材料面向热扩散率的基本原理如图1所示,调制光对试样加热,遮光板沿V方向以一定速度V移动,引起试样上热源边界l变化,假设没有热损失,试样上经历沿。方向的一维导热过程,则热电偶测得之温度幅… 相似文献
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为实现对高速碰撞诱发的闪光辐射温度进行实验测量及误差分析,建立了二级轻气炮加载系统及闪光辐射温度测量系统。采用聚碳酸酯弹丸分别以6 km/s、3.9 km/s的速度垂直撞击2A12铝靶,利用瞬态光纤高温计采集闪光信号,通过比色法计算不同碰撞条件下的闪光辐射强度及辐射温度。依据普朗克辐射定律计算了不同波长及温度条件下的闪光辐射强度理论值,与实验测量结果相比较并进行了误差分析;分别采用双色测温法的不同波长组合及四色测温法计算了闪光辐射温度及其平均温度,通过计算标准差分析了波长的选取对闪光辐射温度的影响。结果表明:与理论计算结果相比较,实验测量得到的闪光辐射强度值偏低,采用双色测温法计算闪光辐射温度时波长的选取对计算结果影响很大,波长间隔越大计算结果误差越小(误差最小值实验No.1为68.25 K,实验No.2为30.67 K);四色测温法计算得到的闪光辐射温度与平均温度相近(误差实验No.1为72.88 K,实验No.2为63.66 K),因此采用比色法计算闪光辐射温度时应尽量选取大间隔波长或多个波长参与计算以降低误差。 相似文献
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在周期加热下薄膜二维导热分析的基础上,探讨了复合股非稳态导热的数值分析方法,并计算了使用周期热流法测量复合膜面向热扩散车时试样上温度波相位和幅值的分布.指出复合膜各膜层导热性质相差很大时,膜材料面向导热与基于一线导热分析的结果是不同的,为复合膜的测量提供了理论基础. 相似文献
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本文讨论了在红外和紫外光谱区测定材料折射率的三种相对法:V棱镜法、菲涅尔法和干涉法,及其测量原理、实验装置、测量方法及误差分析。与绝对法相比较,相对法具有测量方法简便、试样制备容易、对实验室环境要求不苛刻,无需进行温度压力校正等优点。 相似文献
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石英晶体旋光性的温度效应测试研究 总被引:7,自引:0,他引:7
为了测试温度对石英晶体旋光性的影响,采用陶瓷平板型半导体制冷器件作为温控器,设计、建立了石英晶体旋光性温度效应的测试系统,对石英晶体旋光特性的温度效应进行了测试研究:在-10~60℃的温度范围内,从实验上测试了石英晶体的旋光角随温度的变化。实验结果表明:对于确定的单色光,随着温度的升高石英晶体的旋光率增大。根据测试结果,通过求解塞耳迈耶尔方程和四次拟合的方法,得出了塞耳迈耶尔方程的常数与温度的关系式,从而可以得出任意温度下不同波长对应的石英晶体的旋光率。 相似文献
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A new technique is developed to measure the longitudinal thermal expansion coefficient of C/C composite material at high temperature. The measuring principle and components of the apparatus are described in detail. The calculation method is derived from the temperature dependence of the thermal expansion coefficient. The apparatus mainly consists of a high temperature environmental chamber, a power circuit of heating, two high-speed pyrometers, and a laser scanning system. A long solid specimen is resistively heated to a steady high-temperature state by a steady electrical current. The temperature profile of the specimen surface is not uniform because of the thermal conduction and radiation. The temperature profile and the total expansion are measured with a high-speed scanning pyrometer and a laser slit scanning measuring system, respectively. The thermal expansion coefficient in a wide temperature range (1000 - 3800 K) of the specimen can therefore be obtained. The perfect consistency between the present and previous results justifies the validity of this technique. 相似文献
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Viscosity and diffusivity, two important transport coefficients, are systematically investigated from unary melt to binary to multicomponent melts in the present work. By coupling with Kaptay’s viscosity equation of pure liquid metals and effective radii of diffusion species, the Sutherland equation is modified by taking the size effect into account, and further derived into an Arrhenius formula for the convenient usage. Its reliability for predicting self-diffusivity and impurity diffusivity in unary liquids is then validated by comparing the calculated self-diffusivities and impurity diffusivities in liquid Al- and Fe-based alloys with the experimental and the assessed data. Moreover, the Kozlov model was chosen among various viscosity models as the most reliable one to reproduce the experimental viscosities in binary and multicomponent melts. Based on the reliable viscosities calculated from the Kozlov model, the modified Sutherland equation is utilized to predict the tracer diffusivities in binary and multicomponent melts, and validated in Al–Cu, Al–Ni and Al–Ce–Ni melts. Comprehensive comparisons between the calculated results and the literature data indicate that the experimental tracer diffusivities and the theoretical ones can be well reproduced by the present calculations. In addition, the vacancy-wind factor in binary liquid Al–Ni alloys with the increasing temperature is also discussed. What’s more, the calculated inter-diffusivities in liquid Al–Cu, Al–Ni and Al–Ag–Cu alloys are also in excellent agreement with the measured and theoretical data. Comparisons between the simulated concentration profiles and the measured ones in Al–Cu, Al–Ce–Ni and Al–Ag–Cu melts are further used to validate the present calculation method. 相似文献
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In this paper we present results of noncontact measurements of the thermal diffusivity of infrared semi-transparent n-CdMgSe mixed semiconductor crystals by means of the photothermal radiometry (PTR) in a transmission configuration. In order to overcome an influence of the infrared semi-transparency and plasma waves on the PTR signal from n-CdMgSe mixed crystals the samples were covered by thin aluminum foils on both sides. The thermal diffusivities of n-CdMgSe mixed crystals were estimated from PTR phase frequency characteristics using a well-known formula. It was found that the obtained results are underestimated in comparison to thermal diffusivities estimated from the PPE (photopyro-electric) measurements. A three layer model of a PTR signal was applied in order to estimate an error in determination of the thermal diffusivity of a sample caused by aluminum foils. 相似文献
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《Infrared physics》1993,34(4):379-387
Uncooled thermal IR detectors require a suitable absorbing mechanism in order to achieve efficient radiation capture. For bulk detector materials such as ferroelectric ceramics this mechanism may be a broad-band absorber in the form of a metallic black layer, or a thin-film optical interference filter tuned for maximum absorption at the desired wavelength, deposited onto the surface of the detector.A thin metal film having a sheet resistance of 189 Ω per square can absorb 50% of incident radiation, and is employed in the metal film resistance bolometer detector and Golay cell. In this paper an interferometric technique for thin film thermal detectors is described, whereby a thermally sensitive material in the form of a semiconductor or dielectric layer becomes an integral component of a 3-layer absorber stack. The theory of this absorber structure is reviewed and compared with experimental data. It is shown that an effective absorption of 90% can be achieved over the waveband 8–13μm for a blackbody radiation source at 300 K temperature. 相似文献
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Naoyuki Takahashi Takato Nakumura Yoshinori Kubo Katsumi Tamanuki 《Journal of Physics and Chemistry of Solids》2005,66(7):1145-1149
Crystalline quartz films with an AT-cut plane have been grown by catalyst-enhanced vapor-phase epitaxy, at atmospheric pressure, using two quartz buffer layers on a sapphire (110) substrate. In this method, the first quartz buffer layer was deposited on the sapphire (110) substrate at 773 K. After annealing at 823 K, the second buffer layer was deposited at 723 K. The crystal quartz epitaxial layer was then grown at 843 K. The X-ray full-width-at-half-maximum (FWHM) value of the crystalline quartz film obtained was smaller than that of crystalline quartz prepared using a hydrothermal process. The crystalline quality of the quartz films was dependent on the thickness of the buffer layers. Furthermore, it was found that angle control of the cut plane depended on the film thickness of the second buffer layer. The quartz films grown by vapor phase epitaxy show good oscillation characteristics at room temperature. 相似文献
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光电探测器吸收激光后的温升以及因温升造成的各种现象,致使探测器遭受到不同程度的损伤。利用热弹性理论对CO2激光器辐照K9玻璃材料进行研究,建立激光辐照材料温升及热应力分布二维平面模型,通过解析计算得到由激光辐照半导体材料引起的温度场和应力场的瞬态分布。研究表明, K9玻璃材料的激光辐照损伤阀值与辐照时间和光斑半径相关。在同一条件下,造成的热应力损伤阀值较熔融损伤的低,故K9玻璃材料的破坏形态为热应力破坏。 相似文献