气候及老化之因素

FACTORS OF WEATHERING AND CLIMATE

尽管大部分试验都与研究和开发有关 ,但人们从事试验的主要原因仍是为了满足客户对材料的要求。在试验期间或评估结果时可做出若干结论或决定。引起老化的三大主要因素是 :光 (日光辐射 )、水 (湿度 )和温度。但这不仅是每种因素需要多少量才能最终导致材料降解的问题 ,因为辐射波长不同、潮湿程度不同、以及实际温度的冷热循环 ,均会对曝露的材料造成很大 (甚至主要 )的影响。这些因素 (及其变化 )的共同作用导致降解。辐射能量分为直射分量和漫射分量 ,按波段不同又分为紫外部分、可见部分和红外部分。文中给出了各种辐射量的大小、定义和等式。气候在降解过程中起着关键作用。不同气候以不同方式对材料产生作用。

While nearly all testing is done in one way or another for research and development purposes, the main reason why people test is to meet specifications required by those who buy their material. There are several answers or decisions that may be made during a test or in evaluating results. The three main factors of weathering are light (solar radiation), water (moisture) and temperature. But it is not just 'how much' of each of these factors that ultimately cause degradation to materials, because different wavelengths of radiation, different phases of moisture, and actual temperature cycling have a significant, if not greater, effect on materials on exposure. These factors (and secondary effects) work in synergy to cause degradation. Radiant energy can be broken into direct and diffuse components, and different wavelength bands have been categorized into the UV, Visible, and IR regions. Radiometric quantities, definitions, and equations are presented. Climate plays a key role in degradation processes. Different climates will affect materials in varying ways. The two benchmarks for weathering studies include subtropical and desert climates.