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摘要:
为了研究加速老化试验与自然曝晒试验的相关性,进行了飞机典型7B04 T74铝合金-30CrMnSiA钢-7B04 T74铝合金双排8个钢螺钉连接件在防护涂层加速谱下6个周期的加速老化试验和海南万宁2年的自然曝晒试验。观测并记录了不同加速周期和曝晒年限的防护涂层失光、变色、粉化、起泡、开裂、剥落和基体腐蚀现象,对加速老化和自然曝晒的防护涂层表观老化特征、基体腐蚀产物进行了对比分析,表明加速老化试验可以再现外场老化特征。考虑到防护涂层老化特征的多属性和动态性,对2种环境下的老化损伤进行了综合量化评估,用指数函数描述老化特征量随时间的变化规律。通过老化动力学规律的对比,给出了当量加速关系的表示形式,并得到了加速谱和海南万宁自然曝晒试验的当量加速关系为0.4年/周期。
Abstract:In order to study the correlation between accelerated aging test and natural exposure test, a comparative test between the exposure test and accelerated test on typical 7B04 T74 aluminum alloy-30CrMnSiA steel-7B04 T74 aluminum alloy connectors with double row 8 steel screws was carried out. The specimens were accelerated in the protective coating accelerated aging environment for 6 cycles and the natural exposure test of Wanning, Hainan for 2 years, respectively. The aging features including loss of gloss, fading, chalking, bubbling, cracking, flaking and metal substrate corrosion of protective coating were observed and measured, the aging characteristics and matrix corrosion products of accelerated aging and natural exposure protective coatings were compared and analyzed, the comparison on the tested aging characteristics of protective coatings indicates that the accelerated aging test can make the characteristics of the field aging reappear. Considering the multi-attribute and dynamic characteristics of aging characteristics of protective coatings, the aging damage in two environments is comprehensively evaluated quantitatively, and the variation law of aging characteristics with time is described by exponential function. By comparing the aging kinetics, the equation of the equivalent acceleration factor was given. The equivalent acceleration relation between two environments was obtained as 0.4 year/cycle.
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表 1 加速老化试验结果
Table 1. Results of accelerated aging test
评定指标 第1个周期 第2个周期 第3个周期 失光/% 2.6 4.5 5.4 变色 0.51 1.23 1.48 起泡 大小 直径为0~0.1 mm 直径为0~0.5 mm 直径为0.1~2.0 mm 密度 钉头边缘有1~2个气泡 钉头边缘有1~5个气泡 钉头边缘有1~5个气泡;部分钉头边缘有一定量(10个)气泡 开裂 大小 个别孔边有0~1/4圆周的开裂 个别孔边有0~1/2圆周的开裂,部分气泡开裂 数量 剥落 最大尺寸 个别钉表面有直径约为0.3 mm的剥落 个别钉头边缘有直径约为1.0 mm、面积约为1 mm×0.5 mm、4 mm×2 mm的剥落 钉头边缘有直径为0.2~1.5 mm的剥落;个别钉头周围有面积约为4 mm×2 mm的剥落 面积/% 基体腐蚀 蚀点大小 剥落点蚀 剥落点蚀 腐蚀产物 钉头边缘缝隙可见微量白色物质 钉头边缘缝隙有少量白色产物 粉化 用力擦,粘有一定量颜料粒子 用力擦,粘有一定量颜料粒子 用力擦,粘有一定量颜料粒子 评定指标 第4个周期 第5个周期 第6个周期 失光/% 11 14 17 变色 2.31 3.2 3.45 起泡 大小 直径为0.1~5.0 mm 直径为0.1~5.0 mm 直径为0.5~5.0 mm 密度 钉头表面及边缘有较多(>15个)气泡 钉头表面及边缘有较多(>15个)气泡 钉头表面及边缘有较多(>15个)气泡 开裂 大小 个别孔边有1/2圆周开裂,部分气泡开裂 个别孔边有1/2圆周开裂,部分气泡开裂 个别孔边有1/2圆周开裂,部分气泡开裂 数量 剥落 最大尺寸 钉头表面有直径为0.2~2.0 mm的剥落;个别钉头周围有面积约为4 mm×2 mm的剥落 钉头表面有直径约为2.0 mm的剥落;个别钉头周围有面积约为4 mm×2 mm的剥落 钉头表面有直径约为2.0 mm的剥落;个别钉头周围有面积约为4 mm×2 mm的剥落 面积/% 基体腐蚀 蚀点大小 剥落点蚀 剥落点蚀 剥落点蚀 腐蚀产物 钉头边缘缝隙有一定量白色产物 钉头边缘缝隙有较多白色产物 钉头边缘缝隙有较多白色产物 粉化 用力擦,粘有一定量颜料粒子 用力擦,粘有一定量颜料粒子 用力擦,粘有一定量颜料粒子 表 2 自然曝晒试验结果
Table 2. Results of natural exposure test
评定指标 第1年 第2年 失光/% 5.2 16.3 变色 1.39 3.35 起泡 大小 直径为0.1~1.5 mm 直径为0.5~5.0 mm 密度 钉头边缘有1~5个气泡;部分钉头边缘有一定量(10个)气泡 钉头表面及边缘有较多(>15个)气泡 开裂 大小 个别孔边有1/4圆周开裂,部分气泡开裂 个别孔边有1/2圆周开裂,部分气泡开裂 数量 剥落 最大尺寸 个别钉头边缘有直径约为1.0 mm、面积约为1 mm×0.5 mm、4 mm×2 mm的剥落 钉头表面有直径约为2.0 mm的剥落;个别钉头周围有面积约为4 mm×2 mm的剥落 面积/% 基体腐蚀 蚀点大小 剥落点蚀 剥落点蚀 腐蚀产物 钉头边缘缝隙可见微量白色物质 钉头边缘缝隙有较多白色产物 失光 褪色现象不明显,失光率约为5% 褪色现象明显,失光率约为20% 粉化 用力擦,粘有一定量颜料粒子 用力擦,粘有一定量颜料粒子 表 3 腐蚀产物能谱分析结果
Table 3. Energy spectrum analysis result of corrosion products
类别 元素质量分数/% C O Na Mg Al Si S Cl Zn Ti 自然曝晒2年 11.83 58.93 23.18 2.01 2.62 0.83 21.84 51.00 16.91 0.50 0.82 5.77 1.71 6.8 60.02 26.66 2.12 2.87 加速老化5个周期 3.59 61.28 0.32 27.47 0.64 6.71 6.2 53.9 0.36 23.42 0.25 15.86 表 4 单项老化损伤量化结果
Table 4. Quantitative results of single aging damage
单项指标 第1个周期 第2个周期 第3个周期 第4个周期 第5个周期 第6个周期 第1年 第2年 失光/% 2.6 4.5 5.4 11 14 17 5.2 16.3 变色 0.51 1.23 1.48 2.31 3.2 3.45 1.39 3.35 粉化 0 1 1 1 1 1 1 1 起泡 直径/mm 0.2 0.5 0.5 2 3 3 0.5 4 数量/个 2 2 5 15 15 20 4 15 开裂 最大长度/mm 0.2 0.5 1 1 1 1 0.5 1 数量/条 0 1 1 5 10 10 1 9 紧固件生锈 最大直径/mm 0 0.1 1 2 2 2 0.5 2 数量/个 0 1 2 3 4 6 1 5 剥落或基体腐蚀 无 无 无 无 无 有 无 无 表 5 老化损伤等级计算结果
Table 5. Calculation results of aging damage grade
加速时间t/周期 老化损伤d 曝晒时间T1/年 老化损伤D 1 0.51 1 1.21 2 0.90 2 3.49 3 1.56 4 2.42 5 3.46 6 5 -
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