Quantitative analysis of silica aerogel-based thermal insulation coatings

A mathematical heat transfer model for a silica aerogel-based thermal insulation coating was developed. The model can estimate the thermal conductivity of a two-component (binder-aerogel) coating with potential binder intrusion into the nano-porous aerogel structure. The latter is modelled using a so-called core–shell structure representation. Data from several previous experimental investigations with silica aerogels in various binder matrices were used for model validation. For some relevant cases with binder intrusion, it was possible to obtain a very good agreement between simulations and experimental data with shell thickness and/or thermal conductivity of the shell as adjustable parameters. However, the experimental data was not sufficiently detailed to allow a separation of the effects of the two parameters. In the ideal case of no aerogel binder intrusion, a comparison with a coating containing intact hollow glass or polymer spheres showed that silica aerogel particles are more efficient in an insulation coating than hollow spheres. In a practical (non-ideal) comparison, the ranking most likely cannot be generalized. A parameter study demonstrates how the model can be used, qualitatively, to get an indication of the effect of important model parameters on the thermal conductivity of an insulation coating. With relevant data available for service life exposure conditions and raw material costs, the model can also be used as an optimization algorithm.     

新型隔热保温涂料的研制

介绍了一种引入了膨胀微球的新型隔热保温涂料的研制方法,并将该涂料与普通涂料、玻璃微球保温涂料进行了比较。结果表明,引入了膨胀微球后涂料密度大幅降低,隔热和保温(特别是内保温)性能较普通涂料和玻璃微球涂料相比都有了明显的提高。     

隔热涂料和外墙外保温的匹配组合

按照隔热保温机理,可将隔热保温涂料分为反射隔热涂料、辐射隔热涂料及阻隔性隔热保温涂料三类。针对不同地区的气候特点,将隔热保温涂料和外墙外保温组合起来,产生舒适的室内热环境,达到节能的目的。     

Shell powder as a novel bio-filler for thermal insulation coatings

The feasibility of employing shell powder as a novel bio-filler to prepare fluorocarbon coating is demonstrated.According to the relevant Chinese standards, the thermal and mechanical properties of the shell powder-filled fluorocarbon coating were evaluated, and compared with those filled by commercial calcium carbonate. All the shell powder-filled coatings can meet the requirements stated in the relevant standards, and with decreasing the particle size of the shell powders, the performance of the thermal insulation coating is enhanced. The coating(SC3) filled by shell powders with an average particle size of 2.81 μm possesses a better thermal insulation performance than the coating(CC) filled by commercial calcium carbonate. The coating SC3 has comparable adhesive force and washing resistance with the coating CC, and in the washing resistance test, after 2000 cycles, the coating SC3 was still able to cover totally their substrates. This work demonstrates a high value-added disposal method for the aquacultural wastes.     

影响二氧化硅气凝胶隔热涂料热导率的因素

采用溶胶凝胶法及雾化技术制备了二氧化硅气凝胶微球,同时制备了二氧化硅气凝胶隔热涂料。利用扫描电镜（SEM）对涂料的微结构进行观测,采用激光粒度检测仪对二氧化硅气凝胶微球的尺寸进行检测,采用Hot Disk热导率仪测量了二氧化硅气凝胶隔热涂料的热导率。结果显示：根据SEM 图像,气凝胶微球在涂料中形成明显团聚,且在气凝胶体积分数较高时,涂料中气孔增多。此外,小粒径气凝胶微球更容易形成团聚。由于气凝胶微球热阻极大,气凝胶隔热涂料的热导率随气凝胶微球含量的增加而下降。气凝胶微球的团聚相比均匀分散不利于热导率的降低,而孔隙的增多则有利于涂料热导率下降,因为空气的热阻高。小粒径微球的界面热阻比大粒径微球更大,导致小粒径微球制备的隔热涂料热导率低,混合粒径使气凝胶微球堆积密度增大,有利于降低涂料的热导率。     

Thermal insulation of CMAS (Calcium-Magnesium-Alumino-Silicates)- attacked plasma-sprayed thermal barrier coatings

The impact of the penetration of small quantities of calcium-magnesium-alumino- silicates (CMAS) glassy melt in the porous plasma-sprayed (PS) thermal barrier coatings (TBCs) is often neglected even though it might play a non-negligible role on the sintering and hence on the thermal insulation potential of TBCs. In this study, the sintering potential of small CMAS deposits (from 0.25–3 mg.cm⁻²) on freestanding yttria-stabilized zirconia (YSZ) PS TBCs annealed at 1250 °C for 1 h was investigated. The results showed a gradual in-depth sintering with increasing CMAS deposits. This sintering was concomitant with local transformations of the tetragonal YSZ and resulted in an increase in the thermal diffusivity of the coatings that reached a maximum of ∼110 % for the fully penetrated coating.     

一种水性隔热涂料的研制

水性隔热保温涂料属于新一代的功能型涂料,广泛应用于外墙保温。本文以苯丙乳液为基料,在颜填料中引入真空玻璃微珠,对比了不同隔热填料及玻璃微珠加入量对隔热效果的影响,制备了一种环保型隔热涂料,该涂料涂于物体表面可降低其内部环境温度,达到节能降耗的目的。     

Environmentally friendly wooden-based coatings for thermal insulation: Design,manufacturing and performances

The design of an innovative protective and thermal insulating coating is investigated. The coating is composed of two superimposed layers; the innermost layer consists of dried beech dust dispersed in a diluted polyurethane binder, while the outermost layer is a conventional decorative hybrid epoxy-polyester powder coating. Each layer was sprayed on a metal substrate and baked at moderate temperature to consolidate the coatings and establish their full properties. The morphological features, mechanical response, protective and thermal insulating performance of the coatings were experimentally analysed by varying their structure and dried beech dust concentration in the binder. These coatings exhibit high potential in terms of thermal insulation and also show remarkable behaviour in terms of visual appearance, adhesion to the substrate and long lasting.     

Plasma-sprayed nanostructured YSZ thermal barrier coatings: Thermal insulation capability and adhesion strength

Adhesion strength and thermal insulation of nanostructured Yttria Stabilized Zirconia (YSZ) thermal barrier coatings (TBC) were investigated and compared with those of conventional YSZ TBCs. A Nickel based superalloy (IN-738LC) was used as the substrate with NiCrAlY bond coat, and nanostructured and conventional YSZ top coats were applied by using air plasma spray (APS). The adhesion strength of coatings was evaluated according to ASTM C633-01, and their thermal insulation capability was evaluated using a specially designed test setup at an electrical furnace. The results revealed the nanostructured YSZ coating to have a bimodal microstructure consisting of nanosized particles and microcolumnar grains. The bimodal microstructure of nanostructured coatings prevented crack propagation by splat boundaries and unmelted particles, thereby improving the bonding strength. Also, due to the presence of nano-zones in the microstructure of nano TBCs, coatings exhibited superior thermal insulation capability.     

Characterization of coil coatings by thermal analysis

The interrelationship between the network formation process and performance properties makes cure process studies critically important in the coil‐coating industry. The objective of this work was to introduce thermal analysis into the evaluation of curing of uncured samples and in studies of the glass‐transition temperatures of cured samples. Thermal analysis, dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC) were used to characterize gelation and curing of three types of samples: paints, coated sheets, and free films. In addition to the generally used three‐point‐bending and extension geometries, a cup‐and‐plate geometry also was used in analyzing gelation and curing of liquid samples. These thermal analyses are suited to the purpose of characterizing coil coatings. A correlation between PMT (peak metal temperature) and measured T_g (glass‐transition temperature) was found, as well as effectively distinguishing different curing conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2016–2022, 2003     

An accurate and rapid method to compare thermal insulation capacity of nine Gd-Yb-YSZ coatings

The conventional method to evaluate thermal insulation capacity (TIC) of thermal barrier coatings involves the measurement of three parameters, which incurred a large accumulative error. To solve this problem, a self-designed new experimental apparatus was used in this work to compare the TIC of nine ceramic coatings composed of nine ceramic powders with different contents of Gd, Yb, Y and Zr, respectively, synthesized by a new fast hydrothermal method. It was found that the insulation temperature (ΔT) of Yttria-stabilized Zirconia (YSZ) coating mainly depended on the material property and thus reflected the TIC of coating by using this new apparatus. The ΔT value was the temperature difference between a blank sample without coating and a coating sample. The measured ΔT values were found to be highly reproducible. Thus, comparing TIC of the nine Gd-Yb-YSZ coatings by measuring ΔT was more accurate and rapid than the conventional method. The measured ΔT values of nine Gd₂O₃ and Yb₂O₃ added YSZ (Gd-Yb-YSZ) coatings were about 10–20 °C higher than that of YSZ coating at 1050 °C. This indicated that the addition of Gd and Yb enhanced TIC of YSZ coating.     

钛酸钾晶须的表面改性及其在隔热卷材涂料中的应用

利用硅烷偶联剂KH-570对表面无机包覆SiO2前、后的六钛酸钾晶须(PTW)进行有机表面改性,比较了硅烷偶联剂改性无机包覆SiO2处理前、后的PTW对卷材涂料隔热性能的影响.采用红外光谱(IR)、热重分析(TG)方法对改性前后的PTW进行了表征.结果表明,SiO2以化学键键合在PTW表面,KH-570在PTW表面形成了有机包覆层.涂膜隔热性能测试结果表明,以9%SiO2包覆处理后再用偶联剂KH-570改性的PTW能明显改善隔热卷材涂料的隔热性能,其热反射率达到75.4%,比不含PTW的漆膜提高了34.4个百分点,比含直接用偶联剂KH-570改性的PTW的漆膜提高了12.8个百分点.     

On a planar thermal analysis of intumescent coatings

The paper discusses a complex model for a nonstationary planar thermal analysis of expandable intumescent coatings. Following the existing one‐dimensional models, we develop novel and improved equations for the two‐dimensional thermal analysis of intumescent coatings. A progressive expansion due to chemical reactions, phase changes, and the time and temperature‐dependent thermal properties of the coating are considered. In the heating process, the coating may locally experience virgin, intumesced, or charred phases, and their transition with time. The rate of the density loss due to the pyrolysis reaction is described with the Arrhenius equation. The thickness of the coating is assumed to increase enormously during the pyrolysis. Consequently, the energy and mass equilibrium equations are formulated with respect to both the deformed and undeformed configuration. Since most of material properties of commercial products are not given by manufacturers, an innovative procedure is proposed to determine the time‐dependent thermal conductivities and remaining fundamental properties of the coating from the set of measured temperatures. This, together with the two‐dimensional formulation of the thermal equations with respect to the undeformed configuration, makes the present model unique and appropriate for the thermal analyses of an arbitrary steel cross section protected with intumescent coatings.     

建筑隔热涂料综述

文章阐述了隔热涂料的种类,介绍了国内外建筑外墙隔热涂料的研究现状以及发展趋势,同时概述了玻璃用透明隔热纳米涂料的研究进展,最后指出了建筑环保节能保温涂料研究中存在的问题。     

Synthesis,spray granulation and plasma spray coating of lanthanum phosphate nanorods for thermal insulation coatings

Nanorods of lanthanum phosphate obtained by a wet chemical precipitation route were granulated to obtain sizes in the range of 10–15 µm by spray drying from aqueous slurry of 35 wt% solid loading and 2 wt% of PVA binder. The powders thus obtained displayed enhanced flowability and were plasma sprayed on to stainless steel substrates resulting in the formation of adherent coatings of 150–180 µm thickness. These coatings were characterized using electron microscopy, X-ray diffraction analysis and Raman spectroscopy. X-ray analysis indicated phase instability of LaPO₄ during plasma spraying resulting in the formation of oxy and polyphosphates of lanthanum (La₂P₄O₁₃ and La₃PO₇). However, post deposition heat treatment of coated samples at 1100 °C for 2 h resulted in the reversible formation of stoichiometric lanthanum orthophosphate (LaPO₄). Raman spectral analysis was used to confirm the phase structure of the coatings deposited at various plasma input powers. The coatings obtained were found to effectively lower the thermal conductivity of the substrates from ~24 W/mK to less than 19 W/mK (~10%) even at 200 °C.     

Thermal insulation and structural reliability of modified epoxy resin-based ablation thermal protection coatings in aerothermal-vibration coupling environment

Novel hybrid ablation thermal protection coatings (FHMP-ATPCs), employing iron trioxide (Fe₂O₃) powder, hollow glass microspheres, and mica powder as the fillers in hydroxyl-terminated silicone oligomer-bridged epoxy resins (PSG) copolymer, is investigated using an aerothermal-vibration coupling test system. The ablation behavior and structural reliability of FHMP-ATPCs with varying coating thickness were studied. During the test, the total enthalpy of airflow and dynamic pressures are 23 MJ/kg and 300 Pa, accompanied by the random vibration with a frequency of 20–2000 Hz and a total root-mean-square acceleration of 14.9g. The maximum surface and back-face temperatures of the coating with the thickness of 2 mm reached 836.2°C and 156.4°C, respectively. Results also showed that the reduction of thickness obviously suppressed the surface temperature and increase in back-face temperature yet maintaining high structural reliability. Compared with DGEBA-based coatings, the PSG-based coatings showed excellent structural reliability during the test. The study provides a solution for obtaining high performance ATPCs, which are highly desired for supersonic vehicles.     

聚氨酯保温材料在外墙保温系统的应用

综述了聚氨酯外墙外保温施工技术的发展历程及聚氨酯保温材料在外墙保温系统的应用。聚氨酯外墙内保温系统施工成本低、操作简单,但能耗高,尤其室内温度较低的时候,室内的热量会大量通过钢筋混凝土楼板传送到外侧,增加了供热设备的能耗。聚氨酯外墙外保温系统的保温效果更好,但由于聚氨酯保温材料较厚,在与墙体黏结的时候,会出现结构不稳定的现象。因此研究聚氨酯外墙保温系统的发展及应用对节约资源具有重要的意义。     

中华人民共和国国家标准GB/T25261-2010 建筑用反射隔热涂料

<正>1范围本标准规定了建筑用反射隔热涂料的术语和定义、要求、试验方法、检验规则、标志、包装和贮存等内容。本标准适用于建筑物表面隔热保温用涂料。2规范性引用文件下列文件中的条款通过本标准的引用而成为本标准的条款。凡是注日期的引用文件,其随后所有的修改单(不包括勘误的内容)或修订版均不适用于本标准。然而,鼓励根据本标准达成协议的各方研究是否可