红外热像法研究空心砖墙表面温度

建筑墙体的室内表面温度直接反映墙体的保温隔热性能,并且作为室内平均辐射温度的主要组成部分对室内热环境有重要影响。针对建筑工程中大量使用的空心砖墙体具有表面温度不均匀的特点,采用ThermaCAM P20型红外热像仪和ThermaCAM Reporter分析软件,研究应用红外热像法测量空心砖墙体的表面温度,分析空心砖墙体的温度特征以及空心砖、 砌筑砂浆、 配砖等组成材料对表面温度分布的影响。在高层住宅建筑工程现场,选择三层住宅的填充外墙位置,使用不同的烧结页岩空心砖、 砌筑砂浆和配砖砌筑成三种空心砖墙体进行传热实验。通过采集三种烧结页岩空心砖墙体在冬季室内采暖条件下的内表面温度红外热像图,对比分析了两种空心砖和两种砂浆砌筑的墙体表面温度特性数据以及温度均匀性和温度频率分布。结果表明：提高空心砖和砌筑砂浆的保温性,能够有效提高墙体内表面温度,改善室内热环境;由保温砂浆代替水泥砂浆砌筑的节能型烧结页岩空心砖墙体,表面温度的不均匀性从0.6 ℃下降为0.4 ℃,并使表面温度频率分布发生变化,从非对称分布变为正态分布;随着表面温度均匀性的提高,平均温度所占的频率增大。本研究为空心砖墙体热功能的提高和优化提供了依据。     

Infra-red assisted sintering of inkjet printed silver tracks on paper substrates

In this study, conductive silver features using inkjet printing have been successfully prepared and their sintering studied. Regarding conductivity, metallic inks are the most efficient available conductive inks, even if important drawbacks regarding the use of such inks in inkjet still exist. Indeed, the sintering step is an important limiting factor for the productivity and the substrate choice. An infrared (IR) drying method was experimented to optimize the sintering treatment time. Trials with glass and paper substrates were performed and proved that IR drying is interesting to optimize sintering. Indeed a similar level of resistance was obtained for conventional heating (200 °C, 5 min) and for IR radiations within a shorter treatment time (3 min). Moreover, the substrate temperature during the IR sintering treatment was controlled. The substrate appears to be a relevant parameter to optimize sintering because its thermal behaviour directly impacts on the treatment duration. And for the first time a sheet resistance of 1.9 Ω sq⁻¹ was obtained on paper substrate after only 2 min of IR treatment without any observation of substrate degradation. The evaluation of an electrical treatment on the sintering of a nanoparticle film was also performed using a corona pre-treatment. This lead appears to be interesting because the study proves that an electrical treatment can initiate the sintering of silver nanoparticles. The current flow generated by the corona electrodes certainly generates a local heating by dissipation of the conductive pattern. Finally, the solutions presented in this article allow reducing the sintering time of silver conductive inkjet inks. However mainly, it proves that using paper as substrate for such inks is now possible.     

高压烧结法制备Bi2Te3纳米晶块体热电性能的研究

用高压烧结法对水热法制备的Bi₂Te₃纳米线及纳米颗粒粉体进行了压制成型, 并与真空热压法制备的样品进行了形貌和热电性能的比较. 研究表明, 高压烧结样品内的晶粒尺寸明显小于热压样品. 热电性能的研究表明, 高压烧结样品的电阻率、赛贝克系数和热导率均优于真空热压样品. 由纳米线粉体高压烧结的样品其热电优值ZT 在室温时达到了0.5, 高于真空热压样品的值, 表明高压烧结是热电材料纳米粉体成型的一种有效方法.     

Effect of fabrication conditions on the properties of indium tin oxide powders

This paper reports that indium tin oxide （ITO） crystalline powders are prepared by coprecipitation method. Fabrication conditions mainly as sintering temperature and Sn doping content are correlated with the phase, microstructure, infrared emissivity c and powder resistivity of indium tin oxides by means of x-ray diffraction, Fourier transform infrared, and transmission electron microscope. The optimum sintering temperature of 1350℃ and Sn doping content 6～8wt% are determined. The application of ITO in the military camouflage field is proposed.     

超光谱成像仪红外系统热控技术研究

介绍了超光谱成像仪红外系统的应用价值,总结了红外系统在光学元件、焦平面器件、光机结构等不同部分的热控需求。通过主动热控与被动热控的比较,阐述了超光谱成像仪红外系统热控策略,并且归纳了适合其要求的热控技术。其中针对红外系统焦平面热控,对辐射制冷和机械制冷进行了比较,并简要介绍了斯特林制冷机。最后总结了目前超光谱成像仪红外系统热控的关键问题。     

湿法腐蚀进程的红外热像学研究

提出了一种研究湿法腐蚀进程的新方法———红外热像法。在湿法腐蚀中,金属或半导体基片浸泡在化学试剂中,由于化学能的作用,会在溶剂中产生热能,从而发出红外辐射,利用红外热像仪,将探测到的红外辐射信号送至计算机进行处理,得到热像图,从而可以对湿法腐蚀的进程进行分析。理论分析和实验结果都表明,红外热像法可以直观地观测到湿法腐蚀时显著的热扩散过程,从而对湿法腐蚀进程的监测、控制具有指导意义,同时也是红外技术应用的扩展。     

Research on measurement method of selective laser sintering (SLS) transient temperature

During selective laser sintering (SLS), transient temperature has direct effect on prototyping mechanism and quality. The infrared thermograph non-contact testing method is proposed in this paper. The testing results are compared with numerical simulation results. The results indicate that the on-the-spot survey trend agrees with the simulation trend, and the proposed method provides a steady experimental base for selecting sintering parameters and calculating thermophysical parameters reasonably.     

3D modeling and testing of transient temperature in selective laser sintering (SLS) process

In the process of rapid prototyping by the method of selective laser sintering (SLS), transient temperature has direct effect upon the sintering performance. In the present work, a model is developed in order to generate 3D transient temperature field. It uses Al₂O₃ coated ceramic powder and involves the finite element method (FEM) variation of thermal properties and solid–liquid two-phase interface. A high-speed charge coupled device (CCD) image temperature measurement system is used to generate for testing. The obtained test results validates the simulation data and implies that the proposed modeling method is useful in simulating the transient sintering temperature specially when the correct thermal properties and key factors of two-phase interface are main concerns. The performance characteristics of the reasonable sintering parameters are predicted by the proposed modeling method.     

Effect of egassing on the formation of polycrystals from diamond nanopowders produced by detonation and static syntheses

The sintering of diamond nanopowders produced by detonation and static synthesis and degassed through vacuum thermal treatment is studied at an initial pressure of 8 GPa in the temperature range 1200–1600°C. Chemical modification of the initial nanopowders, in combination with thermal treatment in vacuum and encapsulation of the working volume, is shown to suppress graphitization of diamond during sintering, thereby increasing the strength and hardness of polycrystals thus obtained.     

草原枯萎植物的热红外偏振特性研究

为了探究草原枯萎植物的热红外偏振特性,根据热红外偏振的探测机理,利用热红外辐射计对草原枯萎植物样品进行室内测量,发现其热红外偏振辐射亮度、亮温都有随探测角的增大而增大、随方位角和偏振态的增大先增大后减小的趋势,需要特别说明的是虎尾草在180°方位角的亮温是先减小后增大,实验所反映的热红外偏振特性与物质的粗糙程度、探测方向、物质的内部结构及其发射能力有关,该研究为定量研究奠定了基础。     

Ageing evaluation of thermal barrier coatings by thermal diffusivity

Ceramic thermal barrier coatings (TBC) are widely applied for protecting from combustion gases hot path components of gas turbines for both aero- and land-based applications. In order to prevent the detachment of TBC, it would be essential to monitor their degradation in terms of sintering kinetic. As sintering strongly affects also the thermal diffusivity of TBC, the idea is to measure the latter parameter to account for the former. The technique to measure thermal diffusivity using pulsed thermography is described, together with the model that leads to the identification of TBC diffusivity. Tests and results on specimens artificially aged are reported.     

辐射背景对岩石受力热红外光谱变化影响的实验研究

研究表明,岩石在加载过程中表面的红外辐射随应力发展而变化,而辐射信息的有效提取与辐射背景存在密切关系。通过理论分析不同实验环境对岩石受力热红外光谱变化影响,开展了花岗岩在室内外环境下的受力热红外光谱观测实验,分析了不同辐射背景下岩石红外辐射与应力的相关性以及由应力引发的辐射变化信息的强弱差异,并对两种环境下岩石应力热红外探测的优势波段进行了对比分析。结果表明,辐射背景对岩石受力热红外光谱探测结果有重要影响,室外环境因背景辐射较弱,相同应力作用下的红外辐射变化更加显著,与应力之间的相关程度更高,优势波段区间更宽,更加有利于岩石应力的热红外探测。8.0~11.8 μm波段是利用热红外遥感监测地表花岗岩应力变化的优势波段。     

Near-field-enhanced,off-resonant laser sintering of semiconductor particles for additive manufacturing of dispersed Au–ZnO-micro/nano hybrid structures

Off-resonant near-field enhancement by gold nanoparticles adsorbed on crystalline zinc oxide significantly increases the energy efficiency of infrared laser sintering. In detail, ten different gold mass loads on zinc oxide were exposed to 1,064 nm cw-laser radiation. Variation of scan speed, laser power, and spot size showed that the energy threshold required for sintering decreases and sintering process window widens compared to laser sintering of pure zinc oxide powder. Transmission electron microscope analysis after focused ion beam cross sectioning of the sintered particles reveals that supported gold nanoparticles homogenously resolidify in the sintered semiconductor matrix. The enhanced sintering process with ligand-free gold nanoparticles gives access to metal–semiconductor hybrid materials with potential application in light harvesting or energy conversion.     

Temperature fields control in the process of spark plasma sintering of thermoelectrics

The process of creating thermoelectrics by spark plasma sintering of nanostructured powders in order to obtain materials with improved thermoelectric properties has been modeled. The factors that influence the distribution of thermal field in the sintering process have been analyzed. The influence of geometric parameters of tooling on the formation of temperature gradient field required for effective sintering of functionally gradient materials and segmented branches of thermo-elements has been considered. The results can be used to determine the conditions and modes of sintering of functionally gradient materials in installations of spark plasma sintering and hot pressing.     

Physical-mechanical properties of nanocrystalline materials based on ultrafine-dispersed diamonds

The physical-mechanical properties of polycrystals produced on the basis of ultrafine-dispersed diamonds (UDDs) at high static pressures with the use of thermal treatment in vacuum are investigated. The properties of the polycrystals are shown to depend on the sintering conditions and sintering technique, as well as on the modification of the starting powders. With the addition of metals (Co, Ti) to UDD powders, the mechanical strength of compacts increases, their structure improves, and their parameters can be optimized at lower thermobaric treatment temperatures. By studying the products of thermal treatment of UDDs in vacuum, it is established that the compacts and individual particles that form during thermal treatment differ significantly in microhardness.     

聚对苯撑/LiNi0.5Fe2O4纳米复合热电材料的制备及其性能研究

本文以流变相反应法原位合成了聚对苯撑/LiNi_0.5Fe₂O₄纳米复合热电材料,并对其热电性能进行表征,研究了放电等离子烧结时保温时间对其热电性能的影响.结果发现,复合材料铁氧体颗粒粒径为100---300nm,其外部被一层聚对苯撑膜包覆.电子在Fe²⁺和Fe³⁺之间的跳跃机理在铁氧体电导中占主导作用,因此聚对苯撑/LiNi_0.5Fe₂O₄复合材料具有n型导电特性.随着保温时间增加,复合材料电导率基本不变,但热导率逐渐增大且Seebeck系数逐渐减小,导致热电优值系数降低.由于结合了有机物高电导率和低热导率以及无机材料高赛贝克系数的优点,所制备的复合材料热电性能较单一材料有较大提高.     

红外图像伪彩色编码和处理

利用红外热成像系统可将物体的热分布转化为可视图像，并在监视器上以灰度级或伪彩色显示出来，从而得到被测目标的温度分布场。根据热成像测温原理以及红外图像的特点，在对室温热成像系统研究的基础上，对红外图像伪彩色编码进行了研究，提出一种新的伪彩色编码方法，即自动阈值法。利用自动阈值法可以在室温环境下，对目标的温度及其分布进行测量。在TMS320C6202和FPGA室温热成像系统中对提出的方法进行了验证。实验结果表明，该方法可使红外图像层次分明，容易分辨出不同的温度区域。     

基于热红外图像处理技术的农作物冠层识别方法研究

为解决农作物冠层热红外图像边缘灰度级分布不均且噪声较大,而传统图像分割方法难以实现其目标区域有效识别的难题,以苗期红小豆冠层热红外图像为研究对象,将模糊神经网络和仿射变换有机结合,提出了基于热红外图像处理技术的农作物冠层识别模型。首先利用五层线性归一化模糊神经网络的自适应特性,选取高斯隶属度函数,自动计算冠层可见光图像识别的推理规则,有效地分割了可见光图像中的冠层区域。通过分析3种分割指标和熵,定量评价可见光图像冠层分割质量。网络迭代38次时,误差精度为0.000 952,该算法平均有效识别率为96.13%,获取可见光冠层图像的像元信息熵值范围为2.454 4~5.198 7,与标准算法所得冠层图像的像元信息熵仅相差0.245 9。然后以取得可见光图像的冠层有效区域为参考图像,采用仿射变换算法,调整优选平移、旋转、缩放等图像变换因子,配准原始热红外图像,提出了基于仿射变换的冠层热红外图像识别方法。对于初始温度范围值在16.35~19.92 ℃的农作物热红外图像,计算选取旋转幅度为1.0和缩放因子为0.9时,作为异源图像的最优配准参数,获取目标图像的最大温差为3.17 ℃,相对于原图像的平均温度值由18.711 ℃下降至17.790 ℃,进而实现了基于热红外图像处理技术的农作物冠层识别。最后以熵的互信息作为监督指标,对农作物冠层热红外图像识别方法进行评价。提出的冠层热红外图像识别方法,所获取的目标图像与初始热红外图像的平均互信息为4.368 7,标准目标图像和初始热红外图像的平均互信息为3.981 8,二者仅相差0.486 9。同时,两种冠层热红外图像的平均温度差值为0.25 ℃,高效消除了原始热红外图像的背景噪声。结果表明本研究方法的有效性和实用性,能够为应用热红外图像反映农作物生理生态信息特征指标参数提供技术借鉴。     

MRTD高精度测试和校准技术研究

围绕红外热像仪成像参数MRTD（最小可分辨温差）测试问题开展研究，介绍了MRTD的测试方法以及MRTD测试装置—红外热像仪评估系统的工作原理，详细分析了MRTD测试过程中，红外热像仪测试位置、差分黑体温差、差分黑体发射率和光学系统几何像差等因素对测试结果的影响。针对这些问题，提出了采用红外扫描辐射计对红外热像仪评估系统温差进行校准的方法，利用该方法对某空间频率下热像仪MRTD进行测试，并给出了测试结果，为热像仪MRTD参数准确测试提供参考。     

用正电子湮没研究纳米碲化铋的缺陷及其对热导率的影响

利用水热法合成了Bi₂Te₃纳米粉末, 并在300–500 ℃的温度范围内对其进行等离子烧结. X射线衍射测试表明制得的Bi₂Te₃粉末是单相的. 对于300–500 ℃范围内烧结的样品, 扫描电子显微镜观察发现随着烧结温度的升高样品颗粒明显增大, 但是根据X射线衍射峰的宽度计算得到的样品晶粒大小并没有明显的变化. 正电子湮没寿命测试结果表明, 所有的样品中均存在空位型缺陷, 而这些缺陷很可能存在于晶界处. 正电子平均寿命随着烧结温度的升高而单调下降, 说明较高的烧结温度导致了空位型缺陷浓度的降低. 另外, 随着烧结温度从300 ℃升高到500 ℃, 样品的热导率从0.3 W·m^-1·K^-1升高到了2.4 W·m^-1·K^-1, 这表明在纳米Bi₂Te₃中, 空位型缺陷和热导率之间存在着密切的联系.