面漆对湿热环境下膨胀型防火涂层隔热性能的影响

通过105个试件的湿热老化试验和隔热性能试验,研究了2种面漆对膨胀型钢结构防火涂层耐湿热老化性能和隔热性能的影响.结果表明：在经过84次湿热老化循环后,无面漆试件等效导热常数比未老化试件增大131%,涂有2层E型和A型面漆试件的等效导热常数分别比未老化试件增大42%和21%,面漆降低了湿热环境对膨胀型钢结构防火涂层导热系数的影响,涂层隔热性能提高;面漆抑制了涂层膨胀,膨胀层隔热性能降低;当老化时间较短时,面漆对涂层膨胀的抑制作用大于其对涂层耐老化性能的提高,总体上降低了涂层的隔热性能;随着老化时间的延长,面漆的正向作用逐渐显现;膨胀型钢结构防火涂层的隔热性能随面漆厚度的增加而增大.     

膨胀型钢结构防火涂层湿热老化规律研究

膨胀型钢结构防火涂层隔热性能的退化程度受涂料类型、环境条件、使用时间、涂层厚度等因素的影响.为考察上述因素对膨胀型防火涂层耐老化性能的影响,进行了3种工况(变化参数为老化环境及涂料类型)共计78个试件的湿热老化试验及隔热性能试验.结果表明:单组分溶剂型防火涂料在高温高湿环境下更易发生老化;增加涂层厚度可以延缓老化进程;随使用时间延长,涂层防火隔热性能下降,等效导热系数增大,涂层等效导热系数随使用时间变化的规律与涂料类型和环境条件有关.工况1中涂层在老化后期的等效导热系数变化很小,此时涂层与环境所构成的体系已达到一个稳定的平衡状态;工况2和工况3中涂层等效导热系数随时间呈现出递增趋势.     

不同火灾下膨胀型钢结构防火涂层的隔热性能

基于36个试件在标准火与大空间火下的隔热性能测试,计算膨胀型钢结构防火涂层的等效导热系数,研究升温条件对防火涂层隔热性能的影响规律及机理.结果表明,防火涂层是否反应完整取决于火场的最高温度,升温速率影响膨胀-固化阶段防火涂层的发泡程度;升温历史不同,防火涂层的膨胀倍率和炭化层泡孔结构不同,最终表现为防火涂层隔热性能的差异.防火涂层在标准火下的隔热性能优于大空间火下的隔热性能,两者的等效导热系数代表值λr最大差异为65%.升温速率越快,火场最高温度越高,防火涂层的等效导热系数值越低,隔热性能越好,因此,用标准火下防火涂层隔热性能的检测结果来指导大空间火下防火涂层的设计是不安全的.大空间火下防火涂层等效导热系数随升温条件变化的程度还要受涂层厚度的影响,随涂层厚度增加,不同工况下的防火涂层等效导热系数差异程度减小.     

超薄膨胀型钢结构防火涂层的耐湿热性能

为考察超薄膨胀型钢结构防火涂层的防火隔热性能在某一特定环境下随使用时间的变化规律,对36个试件进行了人工加速老化试验和隔热性能试验.结果表明:高湿度环境下,涂层阻燃体系中的亲水性物质(如APP) 会迁移到涂层表面而被溶解,使阻燃体系的组分和配比发生变化,导致高温下阻燃体系的膨胀受阻,从而影响到膨胀倍率和膨胀层内部结构,最终导致膨胀层等效导热系数变大;1,2mm涂层试件的等效导热系数随老化时间总体上呈现出相同的变化规律,与0次循环试件相比,2,4次循环试件涂层的λ-仅增大了1.0%左右,21次循环试件涂层的λ-增大了30.0%,与21次循环试件相比,42次循环试件涂层的λ-仅增大了3.0%左右,表明经过21次循环以后,涂层已达到一个稳定状态.     

升温机制对膨胀型防火涂层隔热性能的影响

对水溶性(W型)和溶剂型(S型)这2种膨胀型钢结构防火涂层在ISO 834标准火及3条非标准火升温曲线下的隔热性能进行了试验研究,其中3条非标准火曲线的升温速率及最高温度均低于标准火.试验结束后对不同升温机制下防火涂层的膨胀倍率和膨胀层的泡孔结构进行定性对比分析,并根据隔热性能试验中温度的测量结果计算防火涂层的等效导热系数,用以对不同升温机制下防火涂层的隔热性能进行定量分析.分析结果表明:升温速率影响膨胀-固化阶段气体的逸出率,进而对防火涂层的膨胀倍率产生影响;升温速率不同,发泡剂分解释放气体的时间与熔融态涂层黏滞性的匹配度不同,炭层的泡孔尺寸不同;膨胀倍率越大,泡孔尺寸越小,炭层的隔热性能越好;与标准火下防火涂层的等效导热系数相比,非标准火下防火涂层的等效导热系数均有不同程度的提高,最大差异为65%(W型)和35%(S型);用标准火下膨胀型防火涂层隔热性能的检测结果来指导非标准火(火场温度和升温速率均比标准火低)下防火涂层的设计将导致不安全的结果.     

面漆对膨胀型防火涂层隔热性能的影响

分别对有无面漆的膨胀型防火涂层保护的钢板试件进行了火灾试验,并对有无面漆的膨胀型防火涂层的膨胀率和等效导热系数进行了对比分析.将钢构件温度为400~600℃时涂层导热系数的平均值作为等效导热系数,并用之来评价有无面漆的膨胀型防火涂层的隔热性能.结果表明:面漆使膨胀型防火涂层的膨胀率降低了30%左右;无论有无面漆,膨胀型防火涂层的等效导热系数都与涂层干膜厚度呈线性关系,有面漆的膨胀型防火涂层等效导热系数比相同厚度的无面漆膨胀型防火涂层等效导热系数增大了30%~70%.     

膨胀型钢结构防火涂层的隔热性能研究

<正>华侨大学的研究人员对膨胀型钢结构防火涂层的隔热性能开展了试验研究。火灾工况包括标准火与大空间火。研究结果表明,火场最高温度决定了防火涂层所经历的反应阶段,升温速率决定了防火涂层在膨胀-固化阶段的发泡程度。标准火下膨胀型钢结构防火涂层的等效导热系数与大空间火下相     

超薄膨胀型钢结构防火涂层的耐湿热性能

针对涂层的耐湿热性能进行初略的研究，借以说明超薄膨胀型钢结构防火涂层的耐湿热性能在各种特定环境下材料产生的外观、性质、形状的变化规律。对试件进行人工加速老化试验以及隔热性能试验。通过试验表明：超薄膨胀型钢结构防火涂层在阻燃体系中亲水性物质通常会迁移至涂层的表层被溶解，超薄膨胀型钢结构防火涂层的阻燃体系分组和配比方面发生变化，使材料的导热性能增强。     

钢结构防火涂料等效热传导系数的确定

针对厚型钢结构防火涂料的热工参数确定问题和膨胀型钢结构防火涂料隔热性能无合适方法评价的现状，提出了根据耐火试验检测测定构件升温过程确定防火涂料等效热传导系数的方法。并分别利用厚型防火涂料和膨胀型防火涂料的检测结果进行试算，取得了较满意的结果。该方法还解决了有膨胀型防火涂料保护层钢构件的温度计算问题，为该类钢构件的抗火计算奠定了基础，并对防火抗火性能试验检测的内容及应提交的结果提出了建议。     

非膨胀型防火涂料等效热传导系数研究

基于防火涂料标准耐火试验方法,对涂覆非膨胀型防火涂料的钢板试件和工字型钢试件进行了耐火试验,用所得的试件升温曲线计算非膨胀型防火涂料的热传导系数随涂层温度变化曲线.提出将涂层温度为400~800℃时的热传导系数平均值作为涂层等效热传导系数,并用以进行被保护钢构件火灾下升温计算,所得钢构件的升温曲线与试验测得的升温曲线符合良好.参数分析表明,等效热传导系数与试件截面形状系数无关,与涂层厚度相关,表明用小尺寸钢板试件耐火试验结果计算所得的等效热传导系数可用于预测其他被保护钢构件在火灾下的升温.对不同涂层厚度热传导系数进行线性拟合,提出以涂层厚度20mm时的等效热传导系数作为非膨胀型防火涂料等效热传导系数特征值.     

Experimental study of hydrothermal aging effects on insulative properties of intumescent coating for steel elements

This paper reports the results of an experimental study of degradation in fire protection performance of two types of intumescent coating after different cycles of accelerated hydrothermal aging tests. Intumescent coating (without top coating) was applied to steel plate to make a test specimen. After subjecting the specimen to the aging test, fire test was carried out to obtain the steel plate temperature. In order to help understand the aging mechanism of intumescent coating, TGA tests, XPS tests and FTIR tests were also conducted on the intumescent coating after the accelerated aging test. In total, tests were performed on 56 intumescent coating protected steel specimens, of which 16 specimens were applied with type-U intumescent coating and the other 40 with type-A intumescent coating. Results of the degradation mechanism study reveal that the hydrophilic components of intumescent coating move to the surface of the coating and can be dissolved by moisture in the air, which can destroy the intended chemical reactions of these components with others and deter formation of the desired effective intumescent char. The consequence of this is reduced expansion of the intumescent coating and increased effective thermal conductivity. Compared to specimens without hydrothermal aging, after 42 cycles of hydrothermal aging (to simulate 20 years of exposure to an assumed exposure environment), the effective thermal conductivity of type-U intumescent coating was 50% higher and that of type-A intumescent coating 100% higher than that of the fresh coating. These increases in effective thermal conductivities resulted in increases in steel temperatures of up to 150 °C and 220 °C higher than the steel temperatures of the specimens without hydrothermal aging for the type-U intumescent coating and type-A intumescent coating specimens, respectively.     

膨胀型透明防火涂料紫外加速老化性能研究

为研究膨胀型透明防火涂料的老化性能,利用紫外加速老化实验箱对氨基类膨胀型透明防火涂料进行了不同老化周期的测试,对涂层老化前后的外观形貌、附着力、耐火性能以及炭层结构进行了表征。结果表明,老化后涂层表面出现一定程度的裂纹和起泡现象,导致涂层完整性和耐火性能下降。聚乙二醇硼酸酯（PEG-BA）的引入有利于减缓涂层老化过程中的开裂、起泡和粉化现象,进而赋予涂层更佳的抗老化性能。涂层抗老化性能与PEG-BA含量密切相关,其中含20%PEG-BA的透明防火涂料经历11周期老化测试后附着力等级仍达到2B级、背部稳定温度低至184.1 ℃,表现出最佳的抗老化性能。     

纳米SiO2对膨胀型防火涂料的紫外老化影响研究

为了研究纳米SiO2对膨胀型防火涂料的耐紫外线性能的影响,对膨胀型防火涂料KB（不添加纳米SiO2）、SY-1（1%纳米SiO2）、SY-2（2%纳米SiO2）和SY-3（3%纳米SiO2）进行了人工紫外加速老化实验,并利用锥形量热仪、扫描电镜、热重分析仪和傅里叶红外光谱分析仪对样品的理化性能进行了分析。结果表明：添加纳米SiO2提高了膨胀型防火涂料的防火性能和耐紫外线性能,并且添加2%纳米SiO2的效果最明显。从对SY-2和KB的老化机理分析发现,纳米SiO2提高膨胀型防火涂料的热稳定性及耐紫外线性能,主要是通过促进树脂与聚磷酸铵交联,抑制酰胺形成,与季戊四醇形成交联结构完成。     

Indicative fire tests to investigate the behaviour of cellular beams protected with intumescent coatings

Applying intumescent coatings, as fire protection, to cellular beams has generally followed a simple design rule based on calculating the Section Factor from which the cellular section was manufactured and then increasing the required thickness by 20%. The validity of the simple design rule has recently been questioned by the Steel Construction Institute who have published new, alternative, design guidance. It was argued that new design guidance was justified since higher than expected web-post temperatures were experienced in recent fire tests on cellular beams. However, these tests were commercially confidential and were not open to scrutiny by the scientific community. This paper presents the results from preliminary indicative fire tests on unprotected and protected cellular and solid beams to investigate the temperatures experienced by the web-post on a cellular beam. It was found that for an unprotected cellular beam there was no increase in web-post temperatures, but for a protected cellular beam the web-post temperatures were higher compared to the web temperatures of an identical solid beam. Observations from the tests, presented in this paper, suggest that the increase in web-post temperatures was due to the intumescent char being ‘pulled-back’ from the circumference of the hole. The tests also indicated that the difference between web-post temperatures and the bottom flange of the cellular beam is dependent on the type and thickness of intumescent coating used. Further tests are required to investigate the behaviour of intumescent coatings around holes before the proposed new generic design guidance is endorsed.     

An experimental study of the thermal performance of a novel intumescent fire protection coating

The thermal performance of a novel intumescent coating was investigated at a laboratory scale. A combination of small and large-scale tests was performed in order to fully understand the behavior of the coating. For small-scale testing, experiments were conducted using thermogravimetric analyses. These experiments were run at several heating rates in a nitrogen atmosphere. The results showed that the thermal degradation of the coating occurred in different stages, and, the main mass loss took place around 300 °C. Furthermore, the current work showed that oxygen doesn't exert any significant effect during the early stages of degradation of the materials; however, its interference can be noted past the attainment of the peak value for mass loss rate curve.For large-scale testing, the experiments were carried out in a cone calorimeter using a stainless steel plate as a platform to support the test specimen. The back surface temperature and expansion height of the intumescent coating were measured as a function of time. Several factors such as heat flux, distance to cone heater and coating thickness were also investigated. The results showed that the normalized expansion height of intumescent coating was consistent at different heat flux levels. Hence the expansion of the coating can be considered to be dependent only on the mass loss rates and not the value of the external heat flux.Also, results from the cone tests, permit the formulation of an experimental protocol for evaluating of the thermal shielding efficiency of the intumescent coatings. The results showed that the data obtained using a cone calorimeter with 2.5 cm of distance cannot be compared with other distances, such as 4 or 6 cm. The present work also showed that the values of the relevant parameters did not differ significantly at distances to the cone heater above 4 cm.In a second evaluation, the new intumescent coating was applied to polyurethane and Gypsum boards, for study using cone calorimetry. The use of the coating led to a decrease in the peak of heat release rate for combustion of polyurethane. The application of a coating layer can be used to decrease the overall requirement of thickness of the Gypsum board without compromising its thermal insulation performance.     

温度对水性钢结构防火涂料性能的影响研究

制备了环氧基水性超薄膨胀型钢结构防火涂料,采用FTIR,TGA和SEM等研究了高低温老化对其性能的影响.结果表明:防火涂料的防火性能、热稳定性、高温耐烧蚀性以及炭化层的强度均随着老化温度的提高而降低.这是由于防火涂料中的防火助剂随着高温老化过程的进行不断迁移损失所致,老化温度越高,防火助剂的损失越严重.进一步的研究表明,防火助剂的损失导致防火涂料的膨胀性能发生变化,炭化层的泡孔尺寸变大,分布不再均匀,从而使炭化层强度降低.     

膨胀型防火涂料炭化层形成过程的探讨

炭化层的形成过程和最终状态是决定钢结构膨胀型防火涂料耐火极限的主要因素 ,因此 ,如何形成轻质、均匀、致密和强度高的炭化层是这类涂料研究和生产的技术关键。膨胀型防火涂料的炭化层形成过程是在高温条件下剧烈的化学反应过程 ,因此 ,涂料配方中的各个组分在这种极端的反应条件下都有可能参与炭化层的形成 ,从而最终影响炭化层的形态。本文通过对有机物体系中常用的阻燃剂———硼酸锌在膨胀型防火涂料中的不同含量对涂料耐火极限和形成炭化层的形态影响 ,得出了硼酸锌的加入对膨胀型防火涂料的炭化层具有负面影响的结论。同时 ,通过涂料配方中不同树脂的试验 ,以及添加表面活性剂对炭化层的作用等 ,得出了各组分对炭化层形态的影响规律。并用泡沫塑料膨胀过程的理论分析对上述实验现象进行解释 ,对钢结构膨胀型防火涂料的配方研制具有实际指导意义。