Prediction For The Color Of Noble Metal

An approach to calculate the color of the noble alloys using first principle and the basic theory of color was proposd in this paper. The color indexes of Au, Ag, Cu, Pt, Pd and Ni were studied. A method was explored to calculate the color index of metals using the reflective of metals calculated by MS and basic theory of color. These tasks will lay a good foundation for binary. alloy, even for the multialloy's calcaulation. After that, the optical properties of Au-Cu, Au-Pd, Cu-Pd binary alloy and Au-Cu-Pd ternary alloy were studied.The result shows that Pd is a bleaching agent, and it should be selected as an important alloying element for the K alloy. The lightness L* of the binary alloys and ternary alloys has a linear rising with the addition of Pd because Pd could enhance the luster of the K alloy. As a kind of toner, Cu can be selected as a major alloying elements for multicolor palladium jewelry. When the content of Pd is more than 50% in Au-Pd alloy or more than 25% in Au-Cu alloy, the alloy's color will be white. Cu in a sense also plays a role of bleach. When Cu and Pd was added into K alloy at the same time, there will be a better effection in reducing chroma and bleaching than one of the elements.On the other hand, color angle is not affected strongly by the alloy's composion. All the alloy's angle in color are between 56°and 76°of the Au and Cu. C* is decided mostly by the the value of b*. The chroma of ternary alloy is basically affected by the content of Pd, and has a small relation with Cu.By the calculation of the binary alloy's color index and lightnes index, the relationship between the color index and lightnes index of the Au-Cu, Au-Pd and Cu-Pd and the composition is illustrated clearly. A series of equations are regressed to correlate color with the alloy compositions. As a result, the color of the alloys can be estimated and forecasted quantitatively.