膨胀型防火涂料的研究进展

介绍膨胀型防火涂料的机理和影响其性能的主要因素以及国内外膨胀型防火涂料的研究状况。     

Laboratory and gas-fired furnace performance tests of epoxy primers for intumescent coatings

Protection of steel structures, using so-called intumescent coatings, is an efficient and space saving way to prolong the time before a building, with load bearing steel constructions, collapses in the event of a fire. In addition to the intumescent coating, application of a primer may be required, either to ensure adhesion of the intumescent coating to the steel or to provide corrosion resistance. It is essential to document the performance of the intumescent coating together with the primer to ensure the overall quality of coating system. In the present work, two epoxy primers were used to investigate the potential failure mechanism of a primer applied prior to an intumescent coating. The analysis was carried out using; (1) gas-fired test furnace, (2) a specially designed electrically heated oven, and (3) thermo gravimetric analysis. When tested below an acrylic intumescent coating, exposed to a gas-fired furnace following the ISO834 fire curve (a so-called cellulosic fire), one of the primers selected performed well and the other poorly. From tests in the electrically heated oven, it was found that both primers were sensitive to the film thickness employed and the presence of oxygen. At oxygen-rich conditions, higher primer thicknesses gave weaker performance. In addition, a color change from red to black was observed in nitrogen, while the color remained red in the oxygen–nitrogen mixture. In summary, the results suggest that an adequate choice of primer, primer thickness, and intumescent coating is essential for a good performance of an intumescent coating system.     

脲醛树脂石蜡微胶囊的制备及其在保温隔热涂料中的应用

以脲醛树脂为壳材料,质量比为1:1:1的液体石蜡、十八烷和固体石蜡组成的混合物为芯材,用原位聚合的方法制备了脲醛树脂石蜡微胶囊,采用红外光谱分析和扫描电子显微镜对微胶囊进行了表征,使用差示扫描量热仪(DSC)研究了石蜡微胶囊的热性能及相变温度。将该微胶囊制成保温隔热涂料,测定了涂料的保温隔热效果及其机械性能。结果显示,脲醛树脂成功包覆了石蜡,微胶囊表面粗糙,粒径为10μm左右,其相变温度分别为2.1°C、15.1°C和42.9°C,相变焓为50.1J/g。与仅含钛白粉的空白涂料相比,添加了空心玻璃微珠、改性硅藻土和脲醛树脂石蜡微胶囊制备的保温隔热涂料最大温差11.5°C,平均温差9.7°C,涂层的机械性能符合国标要求。     

Effects of inorganic fillers on the shear viscosity and fire retardant performance of waterborne intumescent coatings

In the present work, the effects of inorganic fillers on the fire retardant performance of waterborne intumescent coatings are investigated by thermogravimetry (TG), capillary rheometer, X-ray diffraction spectroscopy (XRD) and fire retardant test, etc. The TG results indicate that the thermal stability of vinyl acetate-vinyl ester of versatic acid copolymer (hereafter VAc-VeoVa) in VAc-VeoVa/Si–Al powder composite or in VAc-VeoVa/Halloysite nanometer-tube (HNTs) composite is improved mainly due to the release of the crystal water in Si–Al powder or HNTs. Capillary rheometer analysis results demonstrate that the VAc-VeoVa/HNTs composite melt possesses the highest shear viscosity, because of the large specific surface area of HNTs and the strong interaction force between HNTs and VAc-VeoVa. Weight loss difference (ΔT) of filler/ammonium polyphosphate (APP) composites show antagonism effects at 300 °C < T < 650 °C and synergistic effects at T > 650 °C. The fire retardant test results show the coatings using TiO₂/Si–Al powder/HNTs (8/1/1) as multiple fillers obtains an intumescent char layer with intumescent ratio of 28.14 and presents excellent fire retardant performance (3327 s). It is found that the high melt viscosity, resulted from the effect of inorganic filler, immobilizes the relaxation and rotation of polymer chain, restricts the intumescent behavior of the coatings, which leads to the formation of an intumescent char layer with lower intumescent ratio and the shortening of the fire retardant time. Moreover, the antagonism effect between filler and APP reduces the catalytic dehydration efficiency of pentaerythritol (PER) and VAc-VeoVa, which, as a result, also affects the final fire retardant performance of coatings.     

Testing fire protective properties of intumescent coatings by in-line temperature measurements on a cone calorimeter

An experimental setup was proposed for evaluating the thermal shielding efficiency of intumescent coatings. In particular, a cone calorimeter as heater source was coupled with a thermocouple as detector of the temperature of steel plates coated with intumescent coatings. According to ENV 13381-4 test procedure, the heating curves of the setup was measured by plate thermocouple and compared with ISO 834 standard curve. Meanwhile, the comparison was also made between temperature profiles of blank steel plates at different heat fluxes and unprotected steel elements under ISO fire. The possible correlation between bench scale and large scale test was hence discussed. Several factors (heat flux, distance to cone heater, coating thickness, sample size, edge effect and heat insulator) were deeply investigated and discussed: significant relationships between these parameters and the thermal protective properties of the intumescent coating were evidenced; furthermore a fully developed intumescent char could be obtained by controlling the aforementioned parameters. As a conclusion, the proposed bench-scale test was found to be comparable to the large scale test only in the early heating stages.     

复合型反射隔热涂料的制备与性能研究

采用红外高反射率的空心玻璃珠(BLZ)和彩色空心陶瓷珠(TCZ)制备得到复合型建筑反射隔热涂料,研究了功能性填料、乳液、颜填料及颜填料粒径配比对涂料隔热效果及耐沾污性能的影响。试验结果表明,成膜物质种类的差异对涂料隔热性能的影响较小,当纯丙乳液含量为40%时,隔热温差为14.6℃;二氧化钛能有效提高涂层反射隔热性能,采用20%的二氧化钛添加量能使隔热温差达到15℃左右;填料含量为12%时,具有良好的隔热增强效果,隔热温差为14.6℃;当m(BLZ)/m(TCZ)=1:1时,涂层隔热温差为16.5℃;耐沾污测试表明,当采用纯丙乳液,钛白、硅藻土和滑石粉比例为5:1:1,m(BLZ)/m(TCZ)=2:1时,具有良好的耐沾污性能。     

Effect of heat treatment on microstructure and mechanical properties of cold sprayed Ti coatings with relatively large powder particles

In this study, the effect of post-spray heat treatment on the microstructure, microhardness, and adhesive strength of the cold-sprayed Ti coating was investigated. It was found that a thick and relatively porous Ti coating was deposited by cold spraying. The coating surface layer presented a more porous structure. The microhardness of the as-sprayed Ti coating was slightly higher compared to pure Ti bulk, owing to the work hardening effect during deposition. After annealing at 850°C for 4 h under vacuum condition, the Ti coating also presented a porous structure with more uniformly distributed small pores. A metallurgical bonding between the deposited particles was formed through annealing treatment. The adhesive strength of coating was significantly improved after annealing. The microhardness of the annealed Ti coating was also increased.     

掺杂SnO_2纳米导电氧化物在透明隔热涂料中的应用及前景

介绍了掺杂SnO2纳米导电氧化物TCO浆料的制备及在透明隔热涂料中的应用。     

Resistance to fire of intumescent silicone based coating: The role of organoclay

The fire performance of a curable-silicone based coatings containing expandable graphite (EG) and an organoclay is evaluated in hydrocarbon fire scenario (standard UL1709) using a lab-scale furnace test. It is shown that the use of organoclay allows achieving better performance. The influence of the clay as additional filler is investigated on the fire performance and on the mechanical properties of the char. It is shown that the clay increases significantly the mechanical properties of the char and hence, the fire performance of the silicone based coating. In a next part, the silicone/clay material was characterized by electron microscopy, wide-angle X-ray scattering and solid state ²⁹Si nuclear magnetic resonance (NMR). It evidences the nanodispersion of the clay into the silicone matrix and two main interactions: (i) intercalation of some silicate layers and (ii) chemical reactions between the hydroxyl groups of the clay and the silicone matrix. Finally, X-ray fluorescence of the residue after fire testing shows the organoclay is present uniformly throughout the thickness of the char, due to the previous interaction, and hence increasing the cohesion of the char.     

钢材构件专用隔热防火涂料(非膨胀型)的研制

以改性有机硅树脂为漆基，加入隔热性能优良的颜填料、化学反应型复合阻燃剂、隔热防火剂和高效固化剂N-7或N-9，配制成CT系列室温固化钢结构高层建筑钢材构件专用隔热防火涂料；该涂料可长期耐450℃高温，过火时间大于3h(900℃明火)。     

Different approaches to produce coatings with bioactive glasses: Enamelling vs plasma spraying

Two alternative approaches, enamelling and plasma spraying, were tested to deposit coatings made with two different bioactive glasses: the established Bioglass^® 45S5, which is considered as a term of comparison, and the experimental BioK. The strong points and weaknesses of the two methods were highlighted. From the analysed samples, it resulted that the enamelling approach works well on thermally stable substrates and creates a strong bond, characterized by a compositional gradient, with alumina substrates. However, the coating thickness must be carefully controlled to limit the thermal residual stresses and the glass formulation should be designed to reduce the glass tendency to crystallize. Instead plasma spraying is suitable for any kind of substrate and is highly automatizable, but the equipment is relatively expensive and the coatings are likely to retain some defectiveness, which makes a post-deposition thermal treatment necessary. Both enamelling and plasma spraying may induce crystallization phenomena, depending on the glass formulation. The introduction of potassium oxide in the glass composition, such as in the BioK, may be useful to hinder the crystallization.     

Advantage of heat insulation made of materials with natural porosity

Various heat insulation materials produced at home and abroad are compared. The advantage of using natural nano-structured materials is substantiated. Translated from Novye Ogneupory, No. 7, pp. 41–44, July 2008.     

Thermal cycling behaviors of the plasma sprayed thermal barrier coatings of hexaluminates with magnetoplumbite structure

Hexaluminates with magnetoplumbite structure are important high temperature ceramic materials for thermal barrier coatings (TBCs). Four hexaluminate coatings including NdMgAl₁₁O₁₉ (NdMA), SmMgAl₁₁O₁₉ (SmMA), GdMgAl₁₁O₁₉ (GdMA) and SrAl₁₂O₁₉ (SrHA) were prepared by plasma spraying. During plasma spraying, rare earth (RE) hexaluminates are partially decomposed, resulting in the loss of MgO. For RE hexaluminate coatings, the thermal cycling lifetime decreases with the reduction of RE³⁺ radius, while SrHA has the shortest lifetime. The random arrangement of the platelet-like hexagonal crystals resulted from the recrystallization during thermal cycling may reduce the bond strength of the coatings and make a large contribution to coatings’ failure. The different thermal cycling behaviors of these coatings seem to be dependent on their recrystallization differences to a large extent.     

Manufacture of magnesite-chrome brick for open-hearth furnace roof with heat insulation

Conclusions Roof brick with trapezoidal openings instead of round ones was manufactured under industrial conditions.The possibility in principle has been shown of mass-producing intricately-shaped units with holes not only of re rectangular shape, but also with sharp corners, in the form of a dovetail. The batch production of these parts on hydraulic presses with a single pressing cycle is advised.Research should be carried out on further improving the shape of roofbrick and ceramic suspensions for heat insulated roofs.     

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.