Solution combustion of spinel CuMn2O4 ceramic pigments for thickness sensitive spectrally selective (TSSS) paint coatings

A series of spinel-type CuMn₂O₄ ceramic pigments were prepared by a facile and low-cost sol-gel solution combustion method and used as cost-effective materials to fabricate thickness sensitive spectrally selective (TSSS) paint coatings by a convenient spray-coating technique. The chemical component, crystalline morphology, and optical property of the copper manganese oxide ceramic pigment could be accurately controlled by altering the annealing temperature. X-ray diffraction (XRD) analysis confirmed that the ceramic pigments annealed at 500 °C for 1 h coincided well with the XRD patterns of crystalline CuMn₂O₄ in the JCPDS database, and there were segregated phases of CuO and Mn₂O₃. Furthermore, the pure spinel CuMn₂O₄ phase could be achieved at 900 °C for 1 h. The copper manganese oxide ceramic pigments could serve as an effective pigment for fabricating the TSSS paint coating, and the TSSS paint coatings based on ceramic pigments calcined at 900 °C showed solar absorptance of 0.895–0.905 and thermal emittance of 0.186–0.310. In addition, the accelerated thermal stability test revealed that the TSSS paint coating exhibited good thermal stability when it was exposed to air at a temperature of 300 °C for 300 h. Hence, the fabricated TSSS paint coating could be used as a solar absorber coating in the low-to-mid temperature domain.     

Synthesis of ceria-praseodymia pigments by citrate-gel method for dental restorations

The objective of this paper was to synthesize both pure and praseodymia-doped ceria by using polymeric precursor method for their use as pigments for overlaying coating of dental ceramic restorations. These pigments were characterized by thermogravimetric and differential thermal analyses, X-ray diffraction, X-ray fluorescence, scanning electron microscopy, while UV–vis spectroscopy was used to determinate the reflectance curves of both pure and praseodymia-doped ceria. The referred pigments were added to feldspathic-glass frits in order to simulated the overlaying ceramic coatings on ceramic dental restorations. It was found to be a fluorescent coating by using the synthesized pure ceria but, a coating displaying a shade comparable to those of some commercial opaque layers when using praseodymia-doped ceria pigments with the lowest praseodymia content. Colorimetric coordinate measurements were carried out and used to plot the reflectance curves in the visible range for all types of the considered overlaying coatings.     

Corrosion protection of galvanized sheet by maleic anhydride-g-liquid polybutadiene environmental friendly coatings

Maleic anhydride-g-liquid poly(1,2-butadiene) (MALPB) was modified with diethanolamine (DEA) to prepare anticorrosive coatings by using ethylene glycol monobutyl ether as non-volatile diluents which was considered environmental friendly; their curing processes and anticorrosive performances on galvanized sheet were studied. A robust coating could be obtained through the crosslinking reaction among hydroxyl groups and acids groups, as well as the crosslinking reaction of double bonds by adding peroxides including 0.25% benzoyl peroxide and 1% dicumyl peroxide (wt% of MALPB) as initiators. The Fourier transforming infrared (FTIR) spectra and differential thermo analysis (DTA) results showed that the coatings could be effectively cured at around 260 °C in 5 min. These coatings exhibited good flexibility and adherence on galvanized sheet while their adhesion decreased with the addition of pigments as observed by the digital microscope. As anticorrosive layers on galvanized sheet, these coatings provided effective barriers to electrolyte by impeding their contact with the metal surface; and their anticorrosive capability could be improved by the addition of pigments as observed through the DC polarization tests and salt spray tests.     

Effect of BaO ratio on the structure of glass–ceramic composite materials from the SiO2–Al2O3–Na2O–K2O–CaO system

This article focused on effect of the content of barium oxide on microstructure of the glass–ceramic materials based on the system SiO₂–Al₂O₃–Na₂O–K₂O–CaO. The following characterisation techniques have been used: X-ray diffraction (XRD), scanning electron microscopy with micro-analyser (SEM–EDS), mid-infrared analysis (MIR), far-infrared analysis (FIR) and Raman Spectroscopy. Significant differences were observed in microstructure of silica–alumina network of glassy phase and phase composition related to changes in the amount of the barium oxide additive. Discussed results are part of a larger project implemented under the PBS Applied Research Programme, in order to determine the compositions of glass–ceramic materials with potential application as a chemically resistant hard coatings or/and resistant to thermal shock or as construction materials.     

W61-800各色有机硅耐高温涂料研究

以改性有机硅树脂为成膜物,添加如云母粉、石英粉、石棉粉等填料及低熔点耐高温玻璃粉和陶瓷粉、耐高温颜料、助剂及溶剂制备出一种具有良好耐热性和耐蚀性、在约800℃下可长期使用的耐高温防腐蚀涂料。     

The influence of ceramic additives on intumescence and thermal activity of epoxy coatings for steel

The article presents results of the research on the influence of graphite/kaolin and graphite/titanium oxide systems on thermal properties, intumescence degree and the integrity of the structure of intumescent protective films based on epoxy resins for steel. The TG/DTG/DSC analysis showed that graphite/kaolin system shifted the decomposition reaction of epoxy resin towards higher temperatures, even by about 30°C. Fire endurance tests and the SEM analysis confirmed these results because more thermally resistant (T_500°C reached after 37.5 min for 1.1 coating thickness), swollen (about 20 times) and homogeneous coatings were obtained. The presented results suggest that ceramic fire retardants can successfully cooperate with organic components in intumescent protective coatings for steel elements.     

锆英砂制ZrO_2—SiO_2系陶瓷色料合成机理初探

基于DTA和XRD法对锆英砂制ZrO_2—SiO_2系色料在合成过程的热效应、相组成的分析,提出了色料合成过程的反应历程.     

Heat‐resistant hydrophobic–oleophobic coatings

Thermally and chemically durable hydrophobic oleophobic coatings, containing different ceramic particles such as SiO₂, SiC, Al₂O₃, which can be alternative instead of Teflon, have been developed and applied on the aluminum substrates by spin‐coating method. Polyimides, which are high‐thermal resistant heteroaromatic polymers, were synthesized, and fluor oligomers were added to these polymers to obtain hydrophobic–oleophobic properties. After coating, Al surface was subjected to Taber‐abrasion, adhesion, corrosion, and thermal tests. The effects of the particle size of ceramic powders, organic matrix, and heat on the coating material were investigated. Coating material was characterized by FTIR spectrophotometer. Surface properties and thermal resistance of the coating materials were investigated by SEM and TGA analyses. After thermal curing, contact angles of these coatings with H₂O and n‐hexadecane were measured. It was observed that coatings like ceramic particles are more resistant against scratch and abrasion than the other coatings. Also, they are harder than coatings, which do not include ceramic particles. It was seen that coatings, containing Fluorolink D10H, have high‐contact angles with water and n‐hexadecane. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2386–2392, 2006     

Microstructure and thermal shock resistance of Nd2O3-doped YSZ-based thermal barrier coatings

To study the impact of rare earth oxide doping on the thermal failure of thermal barrier coatings, 0.5 mol%, 1.0 mol% and 1.5 mol% Nd₂O₃-doped YSZ coatings were prepared by explosive spraying. SEM, XRD, EDS and microhardness testing were used to analyse the effect of different rare earth oxide doping contents on the morphology, composition and mechanical properties of the coatings. With an increase in the Nd₂O₃ doping content, the porosity of the coatings was reduced. The decrease in the porosity increased the compactness of the coatings and improved the microhardness and fracture toughness. The bonding strength and thermal shock resistance of the coatings were the highest among the samples herein when the rare earth doping content was 1.0 mol%, and the values were 37.6 MPa and 200 times, respectively. The thermal shock failure mode of the coating was mainly due to the exfoliation of the inner layer of the ceramic layer. The luminous intensity of the coating increased with increasing rare earth oxide doping content, and the emission spectrum of the Nd₂O₃-modified YSZ coating after the thermal shock test produced a new emission peak at 594 nm, which decreased at 708 nm.     

水性热反射船壳漆的研制

研制了一种水性太阳热反射型船壳涂料,考察了不同的基料、相同的隔热颜填料和颜基比对涂层耐介质性能的影响。采用光反射率表征了涂料对可见光、红外光的反射性能。结果表明,以水性聚氨酯树脂为成膜基料,以钛白粉、云母粉、空心陶瓷微珠为隔热功能颜填料,再加上水及助剂等,制备出的涂层与同样体系的溶剂型热反射船壳漆对可见光和近红外光的反射率基本相同。     

Functional colored ceramic coatings obtained by thermal spray for decorative applications

Many inorganic pigments consist of a ceramic matrix doped with transition metal cations, which act as chromophore agents in the ceramic material and provide intense colors. Cassiterite and malayaite are the pigments most commonly used to replace pigments that contain cadmium in the ceramic industry, and are normally deposited using techniques such as CVD, sputtering, sol–gel and spray-pyrolysis. The aim of this study was to produce and characterize SnO₂-based coatings for decorative applications employing a cost-effective technology (APS). The effects of spraying conditions on the crystallinity and microstructure of the coatings were studied. Tests revealed interesting results in terms of the structural features of the coatings, whose optical properties changed. The intrinsic color of the coatings was controlled and compared by reflectivity measurements in the CIELab space, and a change from red-pink to dark-gray was observed for the sample with the highest amount of amorphous cassiterite. The key factor seems to be the percentage of crystalline malayaite, which correlated with the redness value of the color space.     

Effect of Zirconia Concentration on the Growth of Nanowires in Bioactive Glass–Ceramic Coatings

Bioactive glass–ceramic with various zirconia concentrations was applied on stainless steel (SS) by the sol–gel method. Bioactive glass powder was prepared by the sol–gel method, and thermal properties of the prepared powders were studied by differential thermal analysis (DTA). The effects of zirconia were investigated to explore the growth of nanowires. The growth model of nanowires, in this study, is proposed in terms of the surface diffusion. The coatings showed the hardness values to be in the range of 3000–4500 MPa. The hardness values of prepared composite coatings increased with an increase in zirconia amounts.     

Characterization of blue CoAl2O4 nano-pigment synthesized by ultrasonic hydrothermal method

Nano-sized CoAl₂O₄ pigments, which have received significant attention as a coloring agent in glaze and bulk tile compositions, were successfully synthesized by substituting mechanical stirring during hydrothermal process with ultrasonic irradiation. Difference in physicochemical and optical properties of the CoAl₂O₄ pigments prepared by an ultrasonic-assisted-hydrothermal method was characterized using simultaneous thermo-gravimetric and differential thermal analysis (TG–DTA), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), diffuse reflectance spectroscopy, CIELAB colorimetric analysis, and testing in ceramic glazes and bodies. The ultrasonic-assisted CoAl₂O₄ pigments present a narrow particle size distribution with vivid blue color, and better thermal stability, allowing their use for ceramic inks processed at high temperature. Application of ultrasonic irradiation during the hydrothermal process produces nano-sized powders with better physicochemical and optical properties.     

Polysilazane‐based heat‐ and oxidation‐resistant coatings on carbon fibers

Carbon fibers must be protected from a high‐temperature oxidizing environment because, at approximately 500°C and above, the fibers exhibit reduced mass and strength stability. The fibers can be protected by the application of thermal coatings, which simultaneously improve the adhesive properties of the carbon fibers in the composite materials. Polysilazanes are a new family of heat‐resistant polymer coatings that are converted into silicone carbide or silicone nitride ceramic structures at high temperatures. The converted ceramics are resistant to the effects of high temperatures. In this research work, polysilazane‐based coatings were applied to carbon filament (CF) rovings with the dip‐coating method. Tensile testing at room temperature and under thermal stress was carried out to assess the mechanical and thermomechanical properties of both coated and uncoated rovings. Scanning electron microscopy and energy‐dispersive X‐ray analysis were performed to evaluate the surface topographical properties of the coated and uncoated rovings. Thermogravimetric analysis was executed to determine the thermal stability of the polymer coatings. The coating performance on the CF rovings was determined by assessment of the test results obtained. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis of pigments based on the CuO-Cr2O3-Al2O3 system using the precipitation method

Compositions of ceramic pigments for coloring glaze and flux coatings have been developed using the powder method and the coprecipitation method. Comparative parameters of chromophore properties of the obtained pigments are given. The expediency of using the coprecipitation method in the synthesis of ceramic pigments is demonstrated.     

金属基耐高温陶瓷涂层抗热冲击性能的研究

为提高金属基陶瓷涂层的抗热冲击性能，以无机胶粘剂磷酸二氢铝、耐磨陶瓷骨料氧化铝、碳化硅和氧化镁混合后涂覆于金属表面制得陶瓷涂层。通过交替加热及冷却试验测试该陶瓷涂层的抗热冲击性能，并与其他人的研究数据进行比较。所得涂层抗热冲击次数超过10次，超过了其他人的实验数据，这是由于涂层与基体在界面处相互扩散形成过渡层。另外，宏观上的机械联锁有利于提高涂层与基体在界面处的结合，从而提高了其抗热冲击性能。     

CoFe2O4基棕褐色太阳能吸收涂层的制备及性能

采用溶液凝胶法在400℃的低温条件下制备出单相CoFe₂O₄尖晶石型陶瓷颜料。通过XRD、SEM及颜料的红外反射光谱系统的研究了煅烧温度对陶瓷颜料的晶型结构、晶粒尺寸、晶粒形貌以及热发射值的影响。随后,将合成的CoFe₂O₄尖晶石型陶瓷颜料与有机树脂、有机助剂复配,形成吸光涂料。采用操作简单,成本低廉、容易实现大面积制备的涂料喷涂法将所制备的吸光涂料喷涂到高红外反射的金属铝基底上,制备出尖晶石型棕褐色陶瓷太阳能吸光涂层,其太阳能吸收值α_s=0.768~0.818,热发射值为ε₁₀₀=0.315~0.398。棕褐色的涂层也可以满足太阳能户外建筑对色彩的需求。此外,接触角测试表明CoFe₂O₄尖晶石型陶瓷涂层平均水的接触角θ_e>106°,这使得该涂层具备一定的自清洁性能,能有效地应对户外湿度环境对涂层的侵蚀。     

Study on thermal shock resistance of Sc2O3 and Y2O3 co-stabilized ZrO2 thermal barrier coatings

In order to reveal the effect of Sc₂O₃ and Y₂O₃ co-doping system on the thermal shock resistance of ZrO₂ thermal barrier coatings, Y₂O₃ stabilized ZrO₂ thermal barrier coatings (YSZ TBCs) and Sc₂O₃–Y₂O₃ co-stabilized ZrO₂ thermal barrier coatings (ScYSZ TBCs) were prepared by atmospheric plasma spraying technology. The surface and cross-section micromorphologies of YSZ ceramic coating and ScYSZ ceramic coatings were compared, and their phase composition before and after heat treatment at 1200 °C was analyzed. Whereupon, the thermal shock experiment of the two TBCs at 1100 °C was carried out. The results show that the micromorphologies of YSZ ceramic coating and ScYSZ ceramic coating were not much different, but the porosity of the latter was slightly higher. Before heat treatment, the phase composition of both YSZ ceramic coating and ScYSZ ceramic coating was a single T′ phase. After heat treatment, the phase composition of YSZ ceramic coating was a mixture of M phase, T phase, and C phase, while that of ScYSZ ceramic coating was still a single T′ phase, indicating ScYSZ ceramic coating had better T′ phase stability, which could be attributed to the co-doping system of Sc₂O₃ and Y₂O₃ facilitated the formation of defect clusters. In the thermal shock experiment, the thermal shock life of YSZ TBCs was 310 times, while that of ScYSZ TBCs was 370 times, indicating the latter had better thermal shock resistance. The difference in thermal shock resistance could be attributed to the different sintering resistance of ceramic coatings and the different growth rates of thermally grown oxide in the two TBCs. Furthermore, the thermal shock failure modes of YSZ TBCs and ScYSZ TBCs were different, the former was delamination, while the latter was delamination and shallow spallation.     

Characterization of Thermal Barrier Coatings Produced by Various Thermal Spray Techniques Using Solid Powder,Suspension, and Solution Precursor Feedstock Material

Use of a liquid feedstock in thermal spraying (an alternative to the conventional solid powder feedstock) is receiving an increasing level of interest due to its capability to produce the advanced submicrometer/nanostructured coatings. Suspension plasma spraying (SPS) and solution precursor plasma spraying (SPPS) are those advanced thermal spraying techniques which help to feed this liquid feedstock. These techniques have shown to produce better performance thermal barrier coatings (TBCs) than conventional thermal spraying. In this work, a comparative study was performed between SPS‐ and SPPS‐sprayed TBCs which then were also compared with the conventional atmospheric plasma‐sprayed (APS) TBCs. Experimental characterization included SEM, porosity analysis using weight difference by water infiltration, thermal conductivity measurements using laser flash analysis, and lifetime assessment using thermo‐cyclic fatigue test. It was concluded that SPS coatings can produce a microstructure with columnar type features (intermediary between the columnar and vertically cracked microstructure), whereas SPPS can produce vertically cracked microstructure. It was also shown that SPS coatings with particle size in suspension (D₅₀) <3 μm were highly porous with lower thermal conductivity than SPPS and APS coatings. Furthermore, SPS coatings have also shown a relatively better thermal cyclic fatigue lifetime than SPPS.     

Synthesis of gold pearlescent pigment via heat treatment of mica

Pearlescent pigments are widely used to decorate ceramic tableware and architectural ceramics. Coating of mica with high-refractive metal oxides such as titanium oxide is one of the most important synthesis methods of these pigments. However, this process is expensive and long. Moreover, because of the complexity of the process, it is difficult to control and obtain consistent color. This depends on the thickness of the deposited thin film layer. In this study, a low-cost and easy method is proposed to synthesize gold pearlescent pigment. In this case, bulk mica (phlogopite) is heat-treated at appropriate temperatures, determined from related differential thermal analysis (DTA) profiles. Then, the obtained materials are milled for about 2 h and sieved in the 20–60 μm range. X-ray diffraction (XRD) and goniospectrophotometery are used for characterization of the obtained pigment. XRD results showed a few changes in related patterns of the primary sample. In this case, a part of the initial phase of phlogopite was changed to Mg₂SiO₄ (forsterite) and K₂MgSi₅O₁₂ (leucite). Goniospectrophotometer results demonstrated the highest reflectance in the 560–570 nm range (yellow color), and showed a satisfactory level of brightness and lightness of the obtained gold color.