Thermographic NDE advisory and guidance system

Analytical expressions for the thermal contrasts of defects, of varying diameters, depths and openings imaged using the flash and long pulse excitation methods, are presented. Included are: in-plane delaminations; adhesion defects and wall thinning of a fluid filled pipe. The theoretical predictions are shown to be in good agreement with experimental measurements. The analytical expressions have been incorporated in expert system-like software to enable the rapid evaluation of thermographic NDE for a specified application. The system computes the thermal contrast of user defined defects, for both excitation methods, and compares results with typical IR camera performance to assess the suitability of thermographic NDE.     

连铸坯红外热像表面自动探伤系统

为了控制连铸坯表面缺陷,提高钢板的质量和成材率,利用均匀材料与非均匀材料红外热成像的特征差别,提出了一种方便简捷的红外热像连铸坯表面缺陷自动检测系统.采用红外热像装置采集连铸坯图像数据,并通过自动检测图像处理软件进行实时处理,从而实现对连铸坯生产过程的实时监控.采用模块化思想和多线程技术设计了自动检测软件.结果表明,该系统能完成对裂纹图像的实时处理、显示和自动报表等功能.     

Service Performance Evaluation of Graphene Modified Heavy Anticorrosive Coating on the Surface of Transmission Tower under Harsh Marine Atmosphere Corrosive EnvironmentEI北大核心CSCD

目前国家电网输电铁塔普遍采用镀锌钢进行施工建设,钢材表面镀锌层可以抑制基体腐蚀,保障输电铁塔长期安全服役。但在沿海地区的苛刻海洋工业大气腐蚀环境中,输电铁塔表面镀锌层易发生快速腐蚀失效。研制一种低表面处理石墨烯改性重防腐涂料体系,包括低表面处理石墨烯防腐底漆、环氧石墨烯阻隔中间漆和聚氨酯耐候面漆。通过实验室性能测试、 环境考核试验和示范工程涂装,对其服役性能进行综合评价。结果表明：研制的石墨烯改性重防腐涂料具有良好的隔水性和低表面处理施工性能,复合涂层耐盐雾性能超过 5 000 h,耐循环老化 4 200 h 后漆膜完整。在国网宁波供电公司北坞 2321 线 10 级输电铁塔示范涂装 54 个月后,石墨烯改性重防腐涂层光泽度降低,漆膜变色 1 级,百格附着力在 0~1 级,拉拔附着力 8.56~11.37 MPa。根据室内模拟加速试验和实际工程服役性能测试结果,研制的石墨烯改性重防腐涂料对输电铁塔在苛刻海洋大气腐蚀环境下的综合防护寿命可达 10 年以上。研究了石墨烯改性重防腐涂料体系的实际服役性能,实现在苛刻海洋大气腐蚀环境中对输电铁塔的长效腐蚀防护,为电网设施的长期腐蚀防护提供可靠途径。     

Infrared thermography processing based on higher-order statistics

Active thermography has reached a high status as a non-destructive evaluation method due to both ease and speed of inspection. Nevertheless, automatic processing of an infrared (IR) sequence is essential in order to reduce human intervention. Unfortunately, this target is difficult to achieve given the amount of data recorded by the IR camera during a typical inspection process and human participation is absolutely necessary. In this paper, higher-order statistics (HOS) analysis is employed to process IR sequences and to compress the most useful information into a unique image for each inspection. Pulsed infrared thermographic temporal response is well-known with a statistical behaviour. This statistical behaviour is analyzed and the results of its application to carbon fibres reinforced plastic (CFRP) samples are reported.     

高温压力管道红外热成像检测技术

建立了大型管道试验装置，并对带有不同几何尺寸内部开孔缺陷的四种不锈钢和20钢管进行了红外热成像检测试验。结果表明，红外热成像技术十分适用于检测高温压力管道内部腐蚀缺陷，检测灵敏度能够满足压力管道安全运行的要求。     

Improvement of electrochemical performance of Si thin film anode by rare-earth La PIII technique

Si thin film is considered a good candidate for rechargeable Li-ion thin film battery anode material because it possesses large lithium adsorption capacity, good thermal and chemical stability. However, the fast capacity decay upon charge-discharge cycling has hindered the application of Si thin films. In this investigation, Si thin films were sputtered on Cu foils and characterized. One of the explanations for the bad cycling characteristics is the poor adhesion between the Si film and the Cu substrate. Some Cu foils were treated by Plasma Immersion Ion Implantation (PIII) method using rare-earth La element to improve the adhesion strength between the Si thin films and the Cu substrate in order to enhance the cycling performance. Electrochemical analysis revealed that La PIII surface treatment on the Cu foil substrate was effective in strengthening the interface adhesion between the Si thin films and the Cu substrates. Subsequently, the electrochemical performance of the Si thin film anodes was improved.     

蜂窝夹层结构胶接面树脂堆积的红外热像检测

为了研究树脂堆积的红外热像检测问题,文章进行了一维模型建模分析、蜂窝夹层结构样件试验验证和解剖分析。研究发现树脂堆积区域在脉冲加热后的原始热图中表现为"暗区"或"暗斑",并且这些区域的表面温度低于正常胶层厚度区域的表面温度,得出了树脂堆积可以在红外热像检测中被检出的结论。通常树脂堆积不是一种缺陷,但是对蜂窝夹层结构胶接面树脂堆积进行检测却具有重要的现实意义。判断树脂堆积区域的位置、形状和面积,将有助于改进生产工艺。对这些区域进行识别、记录和存档,可以为原位检测蜂窝积水问题提供评定的依据。     

水性涂料在船舶上的应用研究

采用无皂法制备水性丙烯酸乳液,通过半连续滴加工艺进行无皂乳液聚合反应,利用该乳液制备的涂料,研磨分散过程不易破乳,且漆膜与基材的附着力好。通过分析乳液种类、玻璃化转变温度和配套底漆类型对漆膜的外观形貌、附着力及耐盐雾性能影响,得到影响耐盐雾性能的因素。结果表明：利用无皂法制备的丙烯酸乳液水性内舱面漆膜致密;玻璃化转变温度高的无皂乳液耐盐雾500 h内具有优异的性能,而玻璃化转变温度低的在1000 h盐雾的效果更好一些;与溶剂型环氧底漆、水性环氧底漆都具有良好的配套性能,具有优异的附着力和良好的耐盐雾性能。     

缺陷深度脉冲热像检测新方法

介绍脉冲热像检测中由峰值时间求缺陷深度的方法，对热传导性能好的材料，从红外热像时间序列难以捕捉到峰值时间。为此提出了一个既能避开峰值时间又能被红外热像仪探测和记录的新参数，从而达到测量缺陷深度的目的。     

等离子增强磁控溅射技术与纳米复合结构涂层

本文介绍了等离子增强磁控溅射技术（PEMS）的基本原理,以及利用该技术所开发的纳米复合结构涂层,这种涂层的微观结构为纳米颗粒的复合材料—TiSiCN涂层,该涂层具有非常高的表面硬度,具有极好的防腐耐磨性能,同时该涂层的厚度可达560μm,且具有非常好的附着力和柔韧性,不易从基材脱落及脆裂。利用等离子增强磁控溅射技术沉积的纳米复合结构涂层性能良好,具有非常广泛的应用前景。     

缺陷大小和深度的红外检测

介绍红外层析检测的基本原理。为定量测定缺陷，提出由有缺陷区域表面温度和由表面温差达到最大值的峰值时间确定缺陷深度的两种红外检测方法，同时给出由红外热图像确定缺陷尺寸的方法，结果是这些方法更适合于试件浅表面较大面积的缺陷。     

载银自抛光 / 低表面能环保涂层的制备及其耐微生物附着性能研究

目的制备一种新型绿色环保的耐海洋微生物附着涂层。方法通过聚硅氧烷(有机硅)改性丙烯酸树脂,合成以硅氧烷为侧链,丙烯酸树脂为主链的有机硅改性丙烯酸树脂。利用聚多巴胺的粘附性和还原性,制备二氧化硅/聚多巴胺/纳米银(Si O2/PD/Ag)纳米复合材料。以制备的有机硅改性丙烯酸树脂为成膜物,以载银纳米颗粒为杀菌剂,制备耐微生物附着环保涂层。通过傅里叶红外光谱仪(FTIR)和接触角检测仪(CA)分别对有机硅改性丙烯酸树脂的Si—O基团和接触角作表征,通过透射电子显微镜(TEM)表征Si O2/PD/Ag的制备过程,通过水解率和细菌附着等实验评价涂层的防污性能。结果Si—O—Si和Si—O—C的接入使得丙烯酸树脂改性后的接触角从72°提高到96°。Si O2/PD/Ag是一种特殊"核-壳-卫星"结构的载银纳米颗粒,纳米银均匀分散在Si O2的表面。涂层的水解性能良好,水解率为1.03μm/d,杀菌剂分散均匀。结论该涂层通过自抛光和低表面能双重物理抑菌作用和纳米银的杀菌作用,能有效抑制海洋微生物在试样表面的附着。     

Adhesion improvements of Thermal Barrier Coatings with HVOF thermally sprayed bond coats

Thermal barrier coatings (TBC) are an effective engineering solution for the improvement of in service performance of gas turbines and diesel engine components. The quality and further performance of TBC, likewise all thermally sprayed coatings or any other kind of coating, is strongly dependent on the adhesion between the coating and the substrate as well as the adhesion (or cohesion) between the metallic bond coat and the ceramic top coat layer. The debonding of the ceramic layer or of the bond coat layer will lead to the collapse of the overall thermal barrier system. Though several possible problems can occur in coating application as residual stresses, local or net defects (like pores and cracks), one could say that a satisfactory adhesion is the first and intrinsic need for a good coating. The coating adhesion is also dependent on the pair substrate-coating materials, substrate cleaning and blasting, coating application process, coating application parameters and environmental conditions. In this work, the general characteristics and adhesion properties of thermal barrier coatings (TBCs) having bond coats applied using High Velocity Oxygen Fuel (HVOF) thermal spraying and plasma sprayed ceramic top coats are studied. By using HVOF technique to apply the bond coats, high adherence and high corrosion resistance are expected. Furthermore, due to the characteristics of the spraying process, compressive stresses should be induced to the substrate. The compressive stresses are opposed to the tensile stresses that are typical of coatings applied by plasma spraying and eventually cause delamination of the coating in operational conditions. The evaluation of properties includes the studies of morphology, microstructure, microhardness and adhesive/cohesive resistance. From the obtained results it can be said that the main failure location is in the bond coat/ceramic interface corresponding to the lowest adhesion values.     

An application of thermography for detection of delaminations in airport pavements

Since delaminations in airport pavements can lead to failure, cost effective ways must be suggested to inspect the quality of pavements. One of these cost effective ways is the infrared thermography technique. This research paper covers the determination of delaminations in asphalt pavements situated at one of the busiest airports in Greece, the International Airport of Athens, by means of infrared thermography. The infrared thermographic technique is used efficiently in the detection of cracks, flaws and other imperfections appearing on airport pavements. The outcome of this investigation leads to the proposition of a forecasting non-destructive technique intended for assessment of efficient airport pavements.     

Imaging-based detection of AAR induced map-crack damage in concrete structure

Imaging-based inspection methods are increasingly being employed for crack detection in concrete structures, because they provide quantitative information compared to inspections based solely on conventional visual approaches. However, efficient image analysis methods are needed. This study proposes the application of the grey level co-occurrence matrix (GLCM) texture analysis approach and an artificial neural network (ANN) classifier to obtain surface damage information, such as the total amount of superficial cracking, as well as the total length, and range of crack widths. These methods were applied to thermographic, visual colour and greyscale images of concrete blocks from CANMET that were exposed outdoors for ten years, as well as slabs from GRAI that were kept indoors, all specimens exhibiting various levels of alkali-aggregate reaction (AAR) damage. Results of the classifications show that the greyscale imagery performed fairly well, with an overall classification accuracy range of 72.3–76.5% for the CANMET blocks, and 68.7–75.3% for the GRAI slabs. Classifications using the colour imagery were slightly better than the greyscale imagery, with accuracies ranging from 71.4% to 75.2% for CANMET blocks and 70.9–72.0% for the GRAI slabs. The thermographic imagery, however, produced the highest overall classification accuracies, which range from 73.1% to 76.3% for the CANMET blocks and 74.2–76.9% for the GRAI slabs. The results show that all three types of imagery are relatively effective in characterizing and quantifying crack damage; however, the infrared thermography produced more accurate results compared to the visual colour, and greyscale images.     

不同活化方式对橡胶沥青-集料黏附性的影响

目的 通过对橡胶粉进行活化处理,提升橡胶沥青-集料的黏附性。研究不同活化方式对橡胶沥青黏附性的影响,探究橡胶沥青与集料的吸附方式。方法 用接枝活化和涂覆活化的方法对橡胶粉进行预处理,通过扫描电子显微镜(Scanning Electron Microscope, SEM)对活化橡胶粉进行表征。分析了橡胶粉经过活化预处理对橡胶沥青黏附性产生影响的原因。通过接触角试验、表面能理论和水煮法试验,分别评价了3种橡胶沥青的表面自由能(Surface Free Energy, SFE)、能量比(Energy Ratio, ER)和黏附等级,并通过红外光谱(Fourier Transform Infrared Spectroscopy, FTIR)对3种橡胶沥青与集料的吸附方式和黏附机理进行分析。结果 普通橡胶沥青(Crumb Rubber Modified Asphalt, CRMA)、涂覆活化橡胶沥青(Coating Activated Crumb Rubber Modified Asphalt, AC-CRMA)和接枝活化橡胶沥青(Grafting Activated Crumb Rubber Modified Asphalt, AM-CRMA)表面自由能分别为:13.28 mJ/m²、13.79 mJ/m²和15.77 mJ/m²;涂覆活化橡胶沥青能量比相较于普通橡胶沥青提高了4.0%,接枝活化橡胶沥青能量比相较于普通橡胶沥青提高了18.5%,接枝活化橡胶沥青能量比相较于涂覆活化橡胶沥青提高了13.9%;普通橡胶沥青的黏附等级为4级,接枝活化橡胶沥青和涂覆活化橡胶沥青的黏附等级均为5级。结论 对橡胶粉进行活化预处理可以有效改善橡胶沥青的黏附性,同时,接枝活化对橡胶沥青黏附性的提升要优于涂覆活化。     

高引燃脉冲新HiPIMS模式对TiN/CrN多层膜结构和性能的影响EI北大核心CSCD

多层TiN/CrN薄膜能显著改善复杂环境下部件的性能和寿命,为获得性能良好的TiN/CrN多膜层,提出一种高引燃脉冲新HiPIMS模式(高功率脉冲磁控溅射技术)的新放电技术,在一到四引燃脉冲个数条件下制备TiN/CrN多层薄膜。结果表明,随着引燃脉冲个数的增加,TiN/CrN薄膜膜基结合力增加,三引燃脉冲条件下结合力达到HF1(压痕法结合力指标,HF1为性能良好)压痕边缘膜层出现碎裂但膜层并未崩裂,在四引燃脉冲条件下膜基结合力也为HF1,且相较三引燃脉冲膜层碎裂也消失,膜基结合力最佳。同时,随着引燃脉冲个数的增加,膜层的粗糙度下降,磨痕变窄,硬度增强,硬度的波动范围减小,薄膜摩擦因数逐渐降低,四引燃脉冲条件下摩擦因数为0.25,膜层厚度呈先增加后减小的趋势,在三引燃脉冲个数条件下达到最大值332.1 nm试验结果表明引燃脉冲能够强化膜层与基体之间的结合力,硬度以及摩擦磨损的性能,细化晶粒。     

Enhancement of thermographic images as tool for structural analysis in earthquake engineering

In this paper, we present an application of a reconstruction method to thermographic images employed to analyze the response of a masonry structure under seismic actions.At first the theory of linear multivariate sampling Kantorovich operators is presented. By means of the above operators, we are able to reconstruct images taken from thermographic survey of masonry walls, and enhance their quality. Digital image processing of reconstructed images allows us to identify the mutual arrangement of the blocks (made of stones and/or bricks) and mortar joints inside the wall portion analyzed, and therefore the texture of the masonry. Subsequently, the texture has been used to estimate the equivalent elastic properties of the masonry by means of homogenization techniques. Finally a real-world case-study is analyzed, taking into account the mechanical properties estimated from reconstructed thermographic images and evaluating the structural response in terms of modal analysis.     

红外热波检测中热像信号重建引起的伪缺陷现象

在脉冲热激励红外热波检测中,热像信号重建技术（TSR）常用来分析和处理试验结果。该方法的特色是可以增加热像序列的空间和时间分辨率,提高信噪比,减少数据量。同时,该方法还能消除某些伪缺陷的干扰,比如脉冲闪光灯和热像仪镜头的反射所带来的伪缺陷。但是TSR是基于对温度变化曲线进行多项式曲线拟合的,而多项式曲线拟合中,拟合阶数和数据长度对拟合结果影响较大,在某些情况下可能会产生伪缺陷。阐述了热波数据重建技术原理,并以试件表面处于热不平衡状态和表面不均匀进行试验的结果来分析由于数据重建技术所产生的伪缺陷。     

Effect of antimony doped tin oxide on behaviors of waterborne polyurethane acrylate nanocomposite coatings

A multi-functional waterborne polyurethane acrylate (WPUA) nanocomposite coating was prepared through introducing the acrylate groups into the end of the polyurethane main chains and then modified by antimony doped tin oxide (ATO) nanoparticles by ultrasonic dispersion. Structural and morphological features of coatings were assessed using Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and a 3D measuring laser microscope. Performance of the coatings was evaluated using water resistance studies, thermogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA) and mechanical tests such as tensile strength, elongation at break. The data showed that the WPUA/ATO coatings possessed good mechanical properties and thermal stability. The UV-visible-near infrared (UV-VIS-NIR) spectra results suggested that the WPUA/ATO coatings could absorb near infrared radiation so that it would prevent heat transmission and heat diffusion effectively.