ISO 27448:2009标准是一种测试半导体光催化材料自清洁性能的方法。半导体光催化材料是一种具有自清洁性能的材料，可以通过光催化反应将有机物质分解为无害的物质。该标准通过测量水接触角来评估半导体光催化材料的自清洁性能。

水接触角是指水滴与材料表面接触时形成的角度。当水接触角小于90度时，水滴会在材料表面形成一层薄膜，这种现象称为“自清洁效应”。ISO 27448:2009标准通过测量水接触角来评估半导体光催化材料的自清洁性能。

该标准的测试方法如下：

1. 准备测试样品。将半导体光催化材料切割成正方形，边长为10mm，厚度为1mm。

2. 清洗测试样品。将测试样品放入去离子水中，超声波清洗10分钟，然后用去离子水冲洗干净。

3. 测量水接触角。将测试样品放在水平台上，滴入一滴去离子水，然后用相机拍摄水滴与材料表面的接触角度。

4. 计算平均水接触角。重复以上步骤3次，计算平均水接触角。

该标准的测试结果可以用于评估半导体光催化材料的自清洁性能。当水接触角小于90度时，说明材料具有良好的自清洁性能。

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