Influences of glass flakes on fire protection and water resistance of waterborne intumescent fire resistive coating for steel structure

Glass flake (GF) was used as a modifier to improve the fire protection and water resistance of waterborne intumescent fire resistive coating. The influences of GF on the properties of the coatings were investigated in detail by using TGA, XRD, X-ray fluorescence spectrometry (XRF), SEM and fire protection test. The TGA results proved that addition of GF could enhance the anti-oxidation of the char layers and increase the residue weights of the coatings. The XRF results indicated that anti-oxidation of the coatings modified by GF was improved. The SEM images demonstrated that addition of GF could improve the foam structure of the coatings. After immersed in water over 600 h, the results showed that the thermal stability and fire protection of the coating without GF were significant decreased, but the coatings modified by GF could still maintain the excellent intumescent effect and fire protection.     

Influence of nano-boron nitride on fire protection of waterborne fire-resistive coatings

Nano-sized BN and micron-sized BN were used as fillers in fire-resistive coatings. The experimental results suggested that nano-BN with a multilayer structure could remarkably enhance the fire protection of fire-resistive coatings. Turbiscan data indicated that nano-sized BN had better dispersion stability in waterborne coatings than micron-sized BN. TGA results showed that nano-sized BN could enhance the thermal stability of the coatings, especially under high temperature. FTIR and EDS results exhibited that nano-sized BN was helpful in reducing the oxidation degree and enhancing the antioxidation property of the char layer under high temperature. The morphology observation demonstrated that nano-sized BN could improve the foam structure of the char layer so as to improve the mechanical strength of the char layer. Nano-sized BN was helpful for the even distribution of the cells; thus the efficiency of heat insulation of the char layer was enhanced. These results proved that nano-sized BN was beneficial to the forming and expanding of the intumescent char layer, and could provide better fire protection for the coatings.     

Comparative study of the fire protection performance and thermal stability of intumescent fire-retardant coatings filled with three types of clay nano-fillers

The fire protection and thermal stability properties of intumescent fire-retardant coatings filled with three various clay nano-fillers (layer double hydroxide [LDH], montmorillonite [MMT], and sepiolite) were compared by fire protection tests and thermo-gravimetric analysis. The fire protection tests show that the incorporation of three fillers improves the fire protection properties of the intumescent fire-retardant coatings and the addition of 1 wt% sepiolite exhibits the lowest flame spread rating of 9.9 and equilibrium backside temperature of 164.5°C at 900 seconds. TG analysis shows that the incorporation of nano-fillers imparts a considerable enhancement of thermal stability and char formation to the intumescent coatings. Especially, the coating with 1 wt% sepiolite acquires the highest residual weight of 34.2% among the samples. Char residue analysis presents that the introduction of clay nano-fillers plays a positive role in enhancing the compactness and anti-oxidation ability of the char residues, and this positive effect as well as the flame-retardant efficiency depends on the types of clay nano-fillers. The three types of layered clay nano-fillers exhibit synergistic flame-retardant effectiveness in the order of sepiolite > MMT > LDH.     

The effect of zirconia ions on corrosion performance of sol–gel coated galvanized steel

Currently, galvanized steel is treated with hexavalent chrome passivation. Sol–gel coating has been found to be a potential replacement for the hazardous hexavalent chrome passivation treatment. The aim of this work is to study the effect of zirconyl nitrate on corrosion behavior of sol–gel coating. Aminopropyl-trimethoxysilane and 3-glycidoxypropyltrimethoxysilane were employed as precursors to prepare the sol–gel-based silane coating. The sol–gel film was deposited on galvanized steel sheet by dip coating method. The chemical properties of sol–gel solution and coated films were analyzed by infrared spectroscopy. Morphology of the film was characterized by scanning electron microscope. The corrosion resistance of the coated samples was evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization curve, and salt spray test. The results indicated that zirconia-doped coatings have better corrosion resistance in comparison with their undoped counterparts. The coating doped with 0.5% zirconyl nitrate provides better corrosion protection due to the inhibitive action of zirconia ion.     

Influences of silicone emulsion on fire protection of waterborne intumescent fire-resistive coating

The combination of self-crosslinking polyacrylate emulsion and silicone emulsion was used as a binder for the preparation of waterborne intumescent fire-resistive coatings. The influences of silicone emulsion on fire protection and char formation of the coatings were investigated in detail by means of TGA, SEM, energy dispersive spectroscopy analysis, rheological measurement, and fire protection tests. The results showed that using silicone emulsion improved thermal stability and antioxidation ability of the coating and increased the residue weights of the char layer at high temperature. Furthermore, an appropriate amount of silicone emulsion could improve the rheological property of the mixed binders and be conducive to the increase of the intumescent factor of the coatings, thus improving the fire protection of the coating significantly. However, an excess amount of silicone emulsion can lead to uneven dispersion of silicone emulsion in the mixed binder and cause an uneven distribution of cell size of the char layer.     

Influence of buffering on the spontaneous deposition of cerium conversion coatings for corrosion protection of AA2024-T3 aluminum alloy

Cerium-based conversion coatings were spontaneously deposited on AA2024-T3 alloy at 60 °C using buffered and non-buffered CeCl₃ solutions in the presence of H₂O₂. Malonic acid or amino-acetic acid (glycine) was used as buffering additives. The deposition process and the properties of the coatings obtained were followed by linear voltammetry and electrochemical impedance spectroscopy. The surface morphology was studied by scanning electron microscopy. It was found that buffering complicates the conversion process and hampers the deposition rate. The coatings deposited using buffered baths had lower barrier ability and corrosion durability in 3.5 % NaCl corrosive medium compared to those deposited in the absence of buffers.     

Gel-sol synthesis of surface-treated TiO2 nanoparticles and incorporation with waterborne acrylic resin systems for clear UV protective coatings

Visible transparent UV protective coatings were developed by incorporating nano-TiO₂ into waterborne acrylic systems to provide UV protection for UV-sensitive color cool roofing. Water-based high crystalline TiO₂ nanoparticle suspension was prepared via a gel-sol method at a basic pH. The TiO₂ nanoparticles have an average size of 20 nm and are stable against agglomeration. As-prepared TiO₂ nanosuspension is ready to be well dispersed in commercial waterborne acrylic resin system without extra-surface modification. The fabricated TiO₂/acrylic nanocomposite coating achieved a UV cut-off below 350 nm with a visible transmission greater than 85% at 700 nm. It is also demonstrated by using Rhodamine 6G that surface modification of nano-TiO₂ with a SiO₂ insulation layer would suppress the catalytic activity of nano-TiO₂ and improve the UV protection for UV and photocatalysis sensitive dyes.     

Oxidation protection of graphite materials by single-phase ultra-high temperature boride modified monolayer Si-SiC coating

To improve the oxidation resistance of Si-SiC coating, single-phase ultra-high temperature boride (ZrB₂ or TaB₂) modified Si-SiC coating was designed and established on graphite substrates by combination of dipping and reactive infiltration process. ZrB₂ or TaB₂ phase was introduced in Si-SiC coating by directly mixing raw materials and phenol formaldehyde resin in the slurry, and then the ZrB₂-SiC-Si and TaB₂-SiC-Si coatings were fabricated on the graphite samples by dipping-curing, pyrolysis, and siliconizing. The crystalline phases and microstructure of the as-obtained multiphase coatings were investigated by X-ray diffraction analysis and scanning electron microscopy. The interrupted oxidation tests from room-temperature to 1500?°C were conducted to assess the anti-oxidation property of the prepared coatings. After 1200?h of oxidation at 1500?°C in air (30 times thermal cycles), the mass losses of the graphite substrates coated with ZrB₂-SiC-Si and TaB₂-SiC-Si coatings were 0.086% and 0.537%, respectively, and the high-temperature stability of the modified coatings was greatly improved compared to the Si-SiC coating. The excellent anti-oxidation performances of the compound coatings were attributed to the compact structure of the coatings and the formation of compound oxide layers covering on the surfaces. The compound Zr-Si-O and Ta-Si-O films possessed low oxygen diffusion rate and appropriate viscosity, which can provide appreciable oxidation protection for the internal coatings, thus obtaining the excellent oxidation and spallation resistance property.     

氧化石墨烯提高钢结构水性膨胀防火涂料的防火性能研究

以水性丙烯酸树脂为基体,聚磷酸胺、季戊四醇和三聚氰胺为膨胀阻燃体系,加入少量氧化石墨烯制备水性膨胀防火涂料。采用小板燃烧法研究了氧化石墨烯用量对膨胀型防火涂料的阻燃性能的影响。结果表明:加入极少量氧化石墨烯(<0.01%),可提高涂料的阻燃性,当氧化石墨烯含量在0.005%时,涂层的耐燃时间可达432 s,炭层膨胀高度较未加氧化石墨烯涂层增加了13.04%。结合红外光谱(FT-IR)、X射线衍射(XRD)和扫描电子显微镜(SEM)等表征手段对炭层形貌进行分析可知,加入氧化石墨烯后炭层在300~500 ℃范围的热稳定性提高,燃烧炭层完整密实,隔热性能提高,耐燃时间提高。     

65Mn表面电喷镀Ni-Co-P/BN复合镀层的硬度分析

利用电喷镀技术在65Mn表面制备了Ni-Co-P/BN复合镀层。借助Design Expert软件进行了电喷镀Ni-Co-P/BN复合镀层的实验设计,并测试了镀层的表面形貌和硬度。根据测试结果,分析了镀层的组成,并研究了电压、镀液温度、两极间隙、纳米BN微粒的质量浓度对Ni-Co-P/BN复合镀层硬度的影响。结果表明:当电压为16V、镀液温度为70℃、两极间隙为1.6mm、纳米BN微粒的质量浓度为8g/L时,可以在65Mn表面制得光亮且致密的Ni-Co-P/BN复合镀层,其硬度较65Mn基体的硬度显著提高。     

Influence of hydrothermal aging process on components and properties of waterborne fire-resistive coatings

The changes in fire-resistive coatings during the aging process were studied. XPS results proved that the hydrophilic components in fire-resistive coatings migrated from the inside to the outside of the coating in the presence of moisture. This migration behavior changed the compositions and distributions in the coating. The changes of components weakened the intumescent performances of the coating. SEM observations showed that the aging process affected the forming of the foam structure, causing nonuniform distribution of the cells. The thermal stability of the coatings decreased during the aging time. TGA results indicated that the migration behavior also reduced the cooperation between the coating components. XRD spectra showed that less TiP₂O₇ was produced in the char layer after the aging tests, which would reduce the chemical strength of the char layer and the anti-ablation stability under high temperature. EDS results showed that the anti-oxidation property of the coating was also damaged by the aging test.     

环氧防火涂料的研究现状及发展前景

钢结构因其优异性能被广泛应用,是目前最常见的建筑材料之一。但钢材有一些不可忽视的缺点,如温度达到500℃时,钢材的强度将下降50%。因此,对钢结构的建筑往往要做一些防火保护措施,最常用的防火方法是在表面涂一些防火涂料。简述国内钢结构环氧防火涂料的研究现状,分析钢结构防火涂料的发展前景。     

Thermal degradation study of fire resistive coating containing melamine polyphosphate and dipentaerythritol

A melamine polyphosphate (MPP)/dipentaerythritol (DPER) mixture was used as fire retardant additives for preparing waterborne intumescent fire resistive coating. The thermal degradation of the MPP/DPER mixture and of the coating was studied by TGA and FTIR. The resulting char of the coating was investigated by XPS, SEM and energy dispersive spectroscopy (EDS). The results showed that the thermal degradation behavior of the MPP/DPER mixture was similar to that of the coating. They decomposed to nonflammable gases, and formed intumescent char layer containing phosphorus oxide at high temperature. The EDS results proved that the resulting char was gradually oxidized with the temperature increase. The SEM micrographs showed that the average cell size of the char layers became bigger and the cell size distribution became wider as the temperature increased from 500 °C to 800 °C, and this non-uniform char layer could damage the fire protection of the coating.     

Effects of inorganic fillers on the performance of the water-based intumescent fire-retardant coating

The purpose of this research was to evaluate the influences of filler type and its content on the performance of a water-based intumescent fire-retardant coating. Three fillers (vermiculite, celite, and aluminum hydroxide) were added to the intumescent paint formulation. The thermal and fire protective properties were studied with thermogravimetric analysis (TGA), torch test, electrical furnace, scanning electron microscopy (SEM), and Fourier transform infrared analysis (FTIR). The results showed that adding fillers into coatings up to 3% could improve the intumescent coating's behavior and increase its endurance against flames. Of the three fillers used, vermiculite showed a better performance in the torch test, attributed to its chemical and physical structure. Vermiculite has low thermal conductivity and is considered an appropriate filler for heat-insulation. The final back-plate temperatures in the torch test for the vermiculite-containing samples were around 100°C–150°C lower than that of other samples. Moreover, vermiculite's addition improved the coating's expansion by 10% compared with the control sample's. The vermiculite sample's char layer morphology showed a uniform cell size distribution, indicating structural robustness. The coating samples successfully transformed polypropylene flammability from highly flammable to V0 level in the UL 94 vertical burning test standard. The results showed that vermiculite could improve intumescent paint's fire resistance and be used as an enhancer in intumescent coating formulations.     

Effects of natural weathering on the fire properties of intumescent fire‐retardant coatings

Fire‐retardant coatings could be one option for providing enhanced protection to buildings during a wildfire, particularly when applied to combustible siding and in under‐eave areas. Limited studies have been conducted on their effectiveness but maintaining adequate performance after weathering has been questioned. This paper reports on a study evaluating the effect of natural weathering on the performance of intumescent‐type fire‐retardant coatings. The main concerns were (a) the reduction of ignition resistance of the coating after weathering and (b) the coating might contribute as a combustible fuel and assist the fire growth after weathering. This study evaluated the performance of 3 intumescent coatings that were exposed to natural weathering conditions for up to 12 months. A bench‐scale evaluation using a cone calorimeter was used to evaluate the performance of the coatings at 3 heat flux levels (30, 50, and 70 kW/m²). Our results showed that weathering exposure reduced the effectiveness of fire protection of intumescent coatings, but the weathered coatings did not act as additional fuels. Weathering orientation showed much less effect on the performance of intumescent coatings in comparison to other parameters. There was statistical evidence that weathering duration, heat flux level, and coating type affected the combustion properties.     

Self-stratifying coatings based on Schiff base epoxy resins

Schiff base epoxy resin was used as a component of self-stratifying compositions, in which different acrylic resins were used. The degree of stratification was determined using the ATR FTIR spectroscopy and microscopy technique. Results were compared with those for commercial epoxy resins with a comparable epoxy number. A determination was made of the mechanical properties of the coatings obtained. Based on the previous studies, it was concluded that Schiff base epoxy resin in a film-forming composition behaves in a similar manner to BPA-based epoxy resins. The best mechanical properties and a high degree of stratification were achieved using a Schiff base epoxy resin/poly(isobutyl methacrylate) composition. Use of a self-stratifying composition not only reduces the time and cost of preparing a multilayer coating system, thanks to the formation of two layers in one application, but also causes the Schiff based epoxy coatings to become more flexible.     

Effect of artificial weathering and temperature cycling on the performance of coating systems used for wooden windows

The effects of ultraviolet light irradiation and water spray and temperature cycling on the color stability of waterborne coating systems on spruce were investigated. The test samples were treated with three coating systems (white and brown pigmented acrylate waterborne coatings systems with different layering) from six producers. The artificial weathering was carried out based on standardized (504 h) and increased weathering parameters (504 h). Thirty cycles of temperature changes were performed. Discoloration suggesting the rate of degradation process and color stability was measured by a spectrophotometer in L*a*b* color space. The results showed greater color stability of white coating systems during both experiments. The producer of acrylate coatings with iodopropynyl butyl carbamate and permethrin as biocides and benzotriazole, silicon dioxide and methylsiloxane as additives was characterized by the best coatings performance. The most sensitive color parameter to describe the surface quality as a result of irradiation and water spray has proven to be a change of lightness. A tendency towards degradation with increasing lightness was observed during weathering. The effect of temperature itself on color change was minimal. Scanning electron microscopy and energy dispersive spectroscopy revealed microscopic changes of coatings caused by artificial weathering.     

膨胀型钢结构防火防腐涂料性能研究

以磷酸锌为阻锈剂制备了水溶性膨胀型钢结构防火防腐涂料,测试了产品的阻燃性能和防腐性能.结果表明:当磷酸锌的质量分数在8.2%左右时,在保持涂料防火性能的基础上,使其阳极腐蚀过程受到明显的阻滞,实现了兼有防腐和防火的双重功能.用扫描电镜、红外光谱和X射线荧光光谱分析了炭质层的结构,研究了涂料的防火机理.     

Corrosion resistance of compositionally modulated Zn–Ni multilayers electrodeposited from dual baths

By successive deposition from dual baths containing Zn sulfate electrolyte and Ni sulfate–chloride electrolyte, smooth and bright compositionally modulated multilayered (CMM) coatings with different number, thickness and sequence of the sublayers were obtained. The corrosion resistance of the coatings was studied by anode potentiodynamic dissolution and by corrosion potential measurement. With increase in the number of sublayers, regardless of their individual thickness, the correlation between the quantity of Zn, dissolved at more negative potentials (between –1.250 and –0.750 V vs SSE), and the whole quantity of the metal in the coating, decreases. This correlation is smaller in CMM coatings ending with a Ni oversublayer compared to CMM coatings ending with a Zn oversublayer. The corrosion potentials of CMM coatings ending with a Zn oversublayer composed of a great number thin (0.7 m) sublayers, are more positive (0.150/0.200 V) than the potentials of CMM coatings composed of a few thick (3.0 m) sublayers. The most positive corrosion potentials (–0.750/–0.800 V vs SSE) have the CMM coatings ending with a Ni oversublayer; i.e. these multilayered coatings are the most corrosion resistant.     

膨胀型防火涂料及防火机理研究综述

随着技术的不断发展,人们对各个行业广泛应用的木质结构和钢结构的要求越来越高,其中的一个重要关注点就是防火问题。因此,人们开始研究在基材表面覆盖一层防火涂料,发现防火效果较好。从膨胀型防火涂料的分类、组成、特点、防火机理、原料选择等方面对膨胀型防火涂料进行了深入研究,发现其具有良好的防火、抑烟性能,受到了人们的青睐。