반사도와 색 차 분석을 이용한 Cu-Zn 합금의 색 변화 고찰

The change in reflectivity of Cu-Zn alloys was investigated with the modulation of Zn content. The reflectivity of the prepared alloys were compared with pure copper and divided into wavelength regions corresponding to blue, green, yellow, and red colors. As the amounts of Zn increased, the difference in reflectivity of the yellow region increased, and that of the red region decreased. To determine the color difference, the measured reflectivity of the alloys was transformed into a tristimulus value using the Reflectance-Tristimulus value converting equation. Then the tristmulus value was converted into the CIE L*a*b* color space. The color difference was calculated using the color difference formula of the converted L*a*b* values. When 5 at%Zn was added, the color difference value was 3.224, and it increased with increasing Zn content. As the difference in the reflectivity of the green and yellow regions increased, the b* value of the alloys increased and the a* value of the alloys decreased. In this study, the addition of Zn content to Cu alloy induced changes in the reflectivity of the green and yellow wavelength regions, which influences color differences of α-Cu solid solution alloys. (Received November 1, 2017; Accepted December 27, 2017)