Research of Ultra-Black Coating Emissivity Based on a Controlling the Surrounding Radiation Method

A method of controlling the surrounding radiation, proposed to measure the emissivity of the sample with high accuracy, is introduced. Two disks at different temperatures are moved alternately in front of the sample for controlling the surrounding radiation of the sample. The emissivity of the sample is obtained from the relationship between the measured value of the radiation thermometer and the radiation from the sample. There are three samples, including the Japansensor JSC-3, Tempil Pyromark 1200, and NEXTEL Velvet Coating 811-21 ultra-black coating, measured by this method. The uncertainty contributions of this method are analyzed, and the uncertainty of the emissivity measurement method is 0.54 % (k = 1). The surface microstructure of the coatings is measured by scanning electron microscopy, and the relationship between emissivity and the surface properties is discussed.