Ultrasonic characterization of modified Cr_2O_3 coatings by reflection coefficient spectroscopy

Pores,microcracks and density of plasma sprayed Cr2O3 coatings before and after high-intensity pulsed ion beam(HIPIB) irradiation were investigated using the ultrasonic reflection coefficient spectroscopy(URCS).The URCS was analyzed based on an acoustic transmission model for the multi-layered structure.The longitudinal velocity in the coatings was calculated from the experimental URCS,and the attenuation coefficient expression was deduced by comparing the experimental and numerical fitting amplitude spectral lines.The longitudinal velocity of as-sprayed Cr2O3 coating is 2 002 m/s,and increases to 2 099 and 2 148 m/s after being irradiated by HIPIB with 1 and 5 shots.Correspondingly,the factor A changes from 0.046 to 0.026 and 0.020 and n from 1.702 to 1.658 and 1.649 in the attenuation coefficient expression of α=Af n.It is observed that the surface morphology of Cr2O3 coatings changes from rough and porous to smooth and uniform with the increase of shot number,which accords with the ultrasonic analyses reasonably.The URCS seems to provide a convenient and nondestructive method to characterize surface modification of the plasma sprayed coatings.

Thermal Performance of Building Roof with Infrared Reflective Coatings

This paper investigated the applicability and effects of infrared reflective coating on energy consumption of factory building in hot summer and warm winter zone.It first resorted to theoretical calculation,which demonstrated the beneficial effects of infrared reflective coating on reducing building energy consumption.Then it analyzed a field measurement done on two identical rooms respectively with ordinary coated roof and infrared reflective coated roof from November 2006 to October 2007,on a 24h basis.The measured data include exterior and interior roof surface temperature,indoor air temperature,and indoor globe temperature.The related weather data is from a weather station near the measured area.The continuous measurement has been accomplished in southern China,and the measured data indicate that roof surface temperature and heat gain are significantly decreased in summer while slight negative effects in winter are induced by adopting infrared reflective coating.Thus it is simple and applicable to reduce building energy consumption in this area by applying infrared reflective coating.Regress equation between reduced roof thermal property,such as surface temperature and heat gain,and reduction in absorbed solar radiation shows their highly linear relationship.Based on the measured data,it is estimated that the reduced power consumption is 3.45 kWh/m2·month in June.

Three-Component Model for Bidirectional Reflection Distribution Function of Thermal Coating Surfaces

We present a bidirectional reflection distribution function （BRDF） model for thermal coating surfaces based on a three-component reflection assumption, in which the specular reflection is given according to the microfacet theory and Snell＇s law, the multiple reflection is considered Nth cosine distributed, and the volume scattering is uniformly distributed in reflection angles according to the experimental results. This model describes the reflection characteristics of thermal coating surfaces more completely and reasonably. Simulation and measurement results of two thermal coating samples SR107 and S781 are given to validate that this three-component model significantly improves the modeling accuracy for thermal coating surfaces compared with the existing BRDF models.

Kubelka-Munk Revised Theory for High Solar Reflectance and High Long-wave Emissivity Coatings Designing

The Kubelka-Munk revised theory was adopted to derive the mix design theory of high solar reflectance and high emissivity coatings.When the concentration of each colorant is within 20%,and the width of the coating is more than 200 μm,each colorant has enough covering power in visible and near-infrared spectral range.It can be assumed that the addition of colorants in coatings can only change the solar spectral absorption ratio rather than solar spectral scattering coefficient.The spectral scattering coefficient of coatings tends to a constant.The spectral absorption-scattering property of each colorant can be characterized through one parameter.The spectral absorption-scattering coefficient of coatings can be calculated with the multivariate linear relationship of each pigment.Moreover,the results can be expanded for high solar reflectivity and high long-wave emissivity coating preparation.The accuracy of Kubelka-Munk revised theory has been tested and verified through comparison between the calculated value and tested value of coating reflectance.

Dual in-situ observation of tribochemical and morphological evolution of single-layer WS_(2)and multi-layer WS_(2)/C coatings

The outstanding tribological performance of transition metal dichalcogenides(TMDs)is attributed to their unique sandwich microstructure and low interlayer shear stress.This advantageous structure allows TMDs to demonstrate exceptional friction reduction properties.Furthermore,the incorporation of TMDs and amorphous carbon(a-C)in multi-layer structures shows excellent potential for further enhancing tribological and anti-oxidation properties.Amorphous carbon,known for its high ductility,chemical inertness,and excellent wear resistance,significantly contributes to the overall performance of these multi-layer coatings.To gain an in-depth understanding of the tribological mechanism and evolution of TMDs’multi-layer coatings,a dual in-situ analysis was carried out using a tribometer equipped with a 3D laser microscope and a Raman spectrometer.This innovative approach allowed for a comprehensive evolution of the tribological,topographical,and tribochemical characteristics of both single-layer WS_(2)and multi-layer WS_(2)/C coatings in real time.The findings from the dual in-situ tribotest revealed distinct failure characteristics between the single-layer WS_(2)coating and the multi-layer WS_(2)/C coating.The single-layer WS_(2)coating predominantly experienced failure due to mechanical removal,whereas a combination of mechanical removal and tribochemistry primarily influenced the failure of the multi-layer WS_(2)/C coating.The tribological evolution process of these two coatings can be classified into four stages on the basis of their tribological behavior:the running-in stage,stable friction stage,re-deposition stage,and lubrication failure stage.Each stage represents a distinct phase in the tribological behavior of the coatings and contributes to our understanding of their behavior during sliding.

Evaluation of thermal sprayed coating using ultrasonic inspection by means of bottom echo back reflection

Thermal spraying technique is widely used in various mechanical parts as a surface reforming technique.However,as demand to maintain superior mechanical performance in harsh operating environment increases,the need for non-destructive evaluation method for thermal spray coating becomes more important.For this purpose,we thinned the thickness of the thermal sprayed coating by abrasion with blasting and used ultrasonic inspection by means of bottom echo reflection for effective measurement of abrasion quantity in thermal sprayed coating.The results obtained are summarized as follows.When the thickness of thermal sprayed coating becomes thin,the echo height increases.This is because thermal sprayed coatings absorb ultrasonic energy.Ultrasonic energy absorbed by Al2O3 is smaller compared with Fe-13Cr coating.Thermal sprayed coatings submerged in water have a lower echo height compared with air.As mentioned above,the thermal sprayed coating thickness can be estimated using ultrasonic inspection by means of bottom echo back reflection.

THE RESEARCH ON NEW REFLECT ROAD MARK COATING

As the developing of the traffic and transport, road signs coating materials become important more and more. This paper introduces the development and current situation of the traffic marking coating and discusses its raw material and application operation. C 5 petroleum resin made in china is used as major material in a hot melt traffic marking coating. To get the best material composition, orthogonal test is used and wear resistant, water resistant, acidity proof, alkaline proof, adhesive strength, fluid characteristic of the coating is researched.

Accuracy design of ultra-low residual reflection coatings for laser optics

Refractive index inhomogeneity is one of the important characteristics of optical coating material, which is one of the key factors to produce loss to the ultra-low residual reflection coatings except using the refractive index inhomogeneity to obtain gradient-index coating. In the normal structure of antireflection coatings for center wavelength at 532 nm, the physical thicknesses of layer H and layer L are 22.18 nm and 118.86 nm, respectively. The residual reflectance caused by refractive index inhomogeneity（the degree of inhomogeneous is between -0.2 and 0.2） is about 200 ppm, and the minimum reflectivity wavelength is between 528.2 nm and 535.2 nm. A new numerical method adding the refractive index inhomogeneity to the spectra calculation was proposed to design the laser antireflection coatings, which can achieve the design of antireflection coatings with ppm residual reflection by adjusting physical thickness of the couple layers. When the degree of refractive index inhomogeneity of the layer H and layer L is-0.08 and 0.05 respectively, the residual reflectance increase from zero to 0.0769% at 532 nm. According to the above accuracy numerical method, if layer H physical thickness increases by 1.30 nm and layer L decrease by 4.50 nm, residual reflectance of thin film will achieve to 2.06 ppm. When the degree of refractive index inhomogeneity of the layer H and layer L is 0.08 and -0.05 respectively, the residual reflectance increase from zero to 0.0784% at 532 nm. The residual reflectance of designed thin film can be reduced to 0.8 ppm by decreasing the layer H of 1.55 nm while increasing the layer L of 4.94 nm.

Metal Nano Layer Coating for Improving the Detection and Recognition of Micro-Poisons Using Reflection Spectroscopic Measurement

Metal nano layer coating for increasing the sensitivity of spectroscopic measurements is proposed and experimentally demonstrated in this paper. The metal nano layer will attract the micro-poisons from any measured aqueous sample increasing the concentration of the micro-poison in the vicinity of the surface and significantly improves the sensitivity of the spectroscopic measurement. The demonstration was carried out using Fourier Transform Infra-Red (FTIR) operating in the MIR 400 cm-1 - 4000 cm-1 and 5 nm Gold layer which was grown on silicon oxide substrate. In the experimental demonstration Malathion organophosphate pesticide was used as micro-poison. The spectroscopic measurement proves that Malathion was attracted to the metal nano layer. Furthermore, the absorption lines of Malathion were detected and recognized. This proof of principle can be applied to any Internal Reflection Elements (IRE) and it can be used to purify any aqueous solutions and atmosphere from micro-poisons which will be attracted to the metal Nano layer.

The Optical Properties of Black Coatings and Their Estimated Cooling Effect and Cooling Energy Savings Potential

The optical properties of coatings pigmented with different black colorants were systematically investigated and their surface temperatures and cooling energy savings were estimated. The black coatings pigmented with chromite iron nickel black and manganese ferrite black spinel colorants are not cool enough to be energy efficient cool black coatings. The cool black coatings pigmented with NIR-transmitting perylene black and dioxazine purple colorants possess a green shade and a violet shade, respectively. The estimated surface temperature reduction values and annual cooling energy savings in Beijing range from 3.0°C and 1.21 kWhm-2yr-1 for the black coating pigmented with chromite iron nickel colorant to 13.8°C and 5.52 kWhm-2yr-1 for the black coating pigmented with dioxazine purple colorant, respectively.

Wave-absorbing Properties of a Cement-based Coating with MnO2/Activated Carbon Composite

MnO_2/activated carbon composite（Mn-ACC） wave absorber was prepared by the reaction between Mn（CH_3COO）_2 and KMnO_4 on activated carbon. Then, a novel cement based composite absorbing coating（CB-CAC） was prepared by adding the Mn-ACC, manganese zinc ferrite and rubber particles into cement. XRD method was used to analyze the reaction products of the Mn-ACC. The tensile bond strength and the wave absorbing properties of the CB-CACs were also tested. The results showed that the crystallinity of MnO_2 formed in the Mn-ACC was poor. Adding Mn-ACC into the CB-CAC led to first increase and then decrease of the tensile bond strength. The tensile bond strength reached 1.89 MPa with 8.51% of the Mn-ACC. The CB-CACs obtained the optimal absorbing properties with the cement, manganese zinc ferrite, Mn-ACC, rubber particles and H_2O mass ratio of 7.5？7.5？1？1？5.5, respectively. The band width of the reflection below-10 dB was up to 8.8 GHz, which accounted for 57.14% of the test band.

PRELIMINARY STUDY ON RETRO-REFLECTIVE COATED PAPER BASED ON MICROGLASS BEADS

High-reflectivity micro-glass bead, as a kind of retro-reflective material, is widely used in reflective fabric or film and other reflective coatings. But it is rarely used in coated paper. The retro-reflective theory of micro-bead is described. Also the effect of size of micro-bead, dosage of binder and different color layers on reflective properties of coated paper are discussed in this article. The results show that its retro-reflective efficiency is good, equally to reflective fabric or film when the micro-glass bead is used in coated paper.

Experimental and Computational Study of the Microwave Absorption Properties of Recycled α-Fe2O3/OPEFB Fiber/PCL Multi-Layered Composites

The aim of this study was to fabricate multi-layered recycled α-Fe2O3/OPEFB fiber/PCL composites for microwave absorbing applications in the 1 - 4 GHz frequency range. The multi-layered composites were 6 mm thick and each consisted of a 2 mm thick layer of recycled α-Fe2O3/PCL composites at various loadings (5 wt% - 25 wt%) of 16.2 nm recycled α-Fe2O3 nanofiller, placed between two layers of 2 mm thick OPEFB fiber/PCL composites blended at a fixed ratio of 7:3. The real (ε') and imaginary (ε") components of the relative complex permittivity were measured using the open-ended coaxial probe technique and the values obtained were applied as inputs for the Finite Element Method to calculate the reflection coefficient magnitudes from which the reflection loss (RL) properties were determined. Both ε' and ε" increased linearly with recycled α-Fe2O3 nanofiller content and the values of ε' varied between 3.0 and 3.9 while the ε" values ranged between 0.26 and 0.64 within 1 - 4 GHz. The RL (dB) showed the most prominent values within the 1.38 - 1.46 GHz band with a minimum of -38 dB attained by the 25 wt% composite. Another batch of minimum values occurred in the 2.39 - 3.49 GHz range with the lowest of -25 dB at 2.8 GHz. The recycled α-Fe2O3/OPEFB fiber/PCL multi-layered composites are promising materials that can be engineered for solving noise problems in the 1 - 4 GHz range.

可见光减反射膜薄层控制误差的分析与性能优化

为提升光学镜头的成像质量,消除杂散光的影响,以K9玻璃为基底设计可见光波段平均反射率小于0.1%的减反射膜。采用电子束离子辅助沉积的制备方式,针对薄层敏感度高、光谱变化大等问题,通过建立稳定控制膜层厚度的数学模型来减小膜厚误差,提高制备精度和成膜稳定性。对减反射膜进行环测实验,优化调整工艺参数,侧重提高减反射膜的硬度和耐水煮能力。实验结果表明,最终制备出的减反射膜在420~680 nm波段内的平均反射率约为0.044%,最高反射率为0.0712%,克服了以MgF2为外层的减反射膜机械性能和化学稳定性较差的问题,满足工程应用低损耗、稳定可靠、高强度、可重复性制备的要求。

涂层界面反射超声的梳状滤波效应及其结合质量成像检测研究

涂层结构的界面结合质量可以通过超声无损检测技术进行有效表征。基于涂层界面超声传播模型及其反射信号特征研究,发现其回波信号具有梳妆滤波效应。理论分析表明,超声反射系数和相位都会随界面刚度而变化,在此基础上基于梳状滤波效应构建了适用于界面结合强度检测的频域特征参数。利用高频水浸超声扫查系统对不同结合质量的涂层样品进行了成像测试,并与标准划格法测试结果对比。研究结果表明,在涂层结合强度差异较小的情况下,通过回波信号的反射系数和梳状滤波效应频域特征参数都可以区分结合质量为0级和2级样品,而频域特征参数能够显著提升结合质量成像结果的对比度。该研究将为大批量涂层界面质量无损、在线、全覆盖检测提供理论基础与技术支撑。

应用于太赫兹探测器的宽带减反结构设计

在太赫兹波段,高阻硅和蓝宝石具有低吸收率、高电阻率和低光谱色散等优良特性,常被用作器件的衬底材料。然而,它们的折射率与空气存在较大差异,导致从空气入射的太赫兹波在界面发生大量反射,从而降低了波的透过率;同时,还可能会引发法布里-珀罗谐振腔效应,进而限制太赫兹探测器的工作带宽和灵敏度。为降低界面反射,文章提出一种太赫兹波段的三层减反射结构,借助Matlab中传输矩阵法和电磁场仿真中有限元法进行仿真,筛选出Mylar/Al_(2)O_(3)/AlN的材料组合。仿真结果表明,在340 GHz的入射波照射下,该结构在275~405 GHz范围内反射率均低于-20 dB,将其应用于太赫兹探测器后,-3 dB带宽提升至50 GHz以上,响应度提高了3.2倍。该结构制备简单、成本低廉,为太赫兹波段的宽带减反提供了一种经济且有效的解决方案。

基于辐射型反射涂层的热控制墙体性能分析

为评估基于辐射型反射涂层的热控制墙体节能效果,解决相关评测体系缺失问题,建立墙体瞬态传热模型,探究复杂气候交变环境下墙体温度和热流的动态特性,以及辐射换热在被动式制冷过程中的热调控作用,基于热流和墙体传热系数提出一种新的评估模型进行性能评价.结果表明:在室内空调开启情况下,热控制墙体相比于普通墙体,其外表面温度平均下降10.74%,热流提升了281.54%;在夏热冬暖地区,建筑南侧涂覆辐射型反射涂层效果最佳,涂层可以降低建筑全年冷负荷87.8 MJ/m2;在夏热冬冷地区,建筑西面涂覆辐射型反射涂层可以降低建筑全年总负荷26.3 MJ/m2.所提出的性能评价指标能够刻画热控制墙体一天内的传热过程和传热特性,进而得到墙体的折合传热系数,对指导实际建筑施工、降低建筑全生命周期总能耗有重要意义.

BaSO_(4)/ZrO_(2)隔热涂层的制备及性能

[目的]BaSO_(4)不仅成本低,来源丰富,而且具有较高的太阳光反射比和半球发射率,但作为隔热填料应用于涂料中时,隔热性能不如金红石型TiO_(2)和SiO_(2),因此需要对BaSO_(4)进行改性以提升其隔热性能。[方法]以BaSO_(4)及ZrO_(2)粉体为原料,通过煅烧法获得BaSO_(4)/ZrO_(2)粉体,并以BaSO_(4)/ZrO_(2)粉体为隔热填料,纯丙乳液为成膜物质,制备BaSO_(4)/ZrO_(2)隔热涂层。利用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、扫描电镜(SEM)和能谱仪(EDS)对粉体的化学结构及形貌进行表征,并探讨ZrO_(2)添加量对涂层性能的影响。[结果]随着ZrO_(2)添加量的增加,涂层的太阳光反射比、近红外反射比和半球发射率均先升高后降低,隔热温差先增大后减小。当ZrO_(2)添加量为5%(质量分数)时,涂层的太阳光反射比为0.809,近红外反射比为0.785,半球发射率为0.92。此时,BaSO_(4)/ZrO_(2)涂层的隔热温差达到11.29℃,与BaSO_(4)涂层相比高3.12℃,与以未煅烧BaSO_(4)/ZrO_(2)制备的涂层相比高4.52℃。[结论]本研究结果可为基于改性BaSO_(4)的隔热涂料技术和产品的开发提供参考。

原位界面聚合工艺制备超高水分含量微胶囊

为提高微胶囊的含水量、降低填料用量,报道了一种超高水分含量山梨醇水溶液微胶囊的原位界面聚合新工艺。以山梨醇水溶液为芯材,甲苯-2,4-二异氰酸酯和二乙烯三胺界面聚合形成壁材,将分散相以小液滴形式注入到连续相,在两相接触瞬间原位反应开始形成微胶囊壁材,微胶囊水分含量能够达到80%。将该微胶囊制备成伪装涂层后,在400~2500 nm波段内具有和绿色植物相似的反射光谱曲线,与冬青卫矛叶片的光谱相似度达0.9296;伪装涂层的单位面积质量仅为213.9 g/m^(2),涂层附着力达2级。制得的微胶囊水分含量高,应用于伪装涂层后质轻、用量较少、与植物光谱匹配度高、工艺简单,在对抗高光谱探测领域具有良好的应用前景。

光伏镀膜玻璃研究进展及发展趋势

光伏镀膜玻璃是指在玻璃原片上制备一层或多层膜以减反增透,提升光学性能和耐环境老化性能,从而提高光伏组件发电效率。文中介绍了光伏镀膜玻璃的基本原理,通过典型产品的膜层结构、膜层厚度、孔隙率等参数分析不同产品的光学性能和微观结构差异。结合市场需求和前沿技术,从多功能化、薄片化、定制化、环保化等角度探讨了光伏镀膜玻璃的发展趋势。海洋环境等极端环境条件下的应用也对光伏镀膜玻璃提出了新的挑战。相关结果可为光伏镀膜玻璃的生产和研究提供参考和依据,也可为产品开发和市场拓展提供思路。