Variations of color with alloying elements in Pd-free Au–Pt-based high noble dental alloys

Abstract

The effects of alloying addition of a small amount of base metals (In, Sn, Fe, Zn) on color variations in Pd-free Au-Pt-based high noble dental alloys were investigated in terms of rectilinear and polar color coordinates. The ternary Au-Pt-X (X = In, Sn, Fe, Zn) and quaternary Au-Pt-In-Y (Y = Sn, Fe, Zn) alloys were prepared from high purity component metals. The amount of alloying base metals, X and Y, were restricted up to 2 at.%. The alloying addition of a small amount of Fe, In, Sn, to a binary Au-10 at.% Pt alloy (referred to as AP10) effectively increased chroma, C*. On the other hand, the addition of Zn to the parent alloy AP10 did not change color coordinates greatly. The increase in chroma in the present Au-Pt-based high noble alloys was attributed to the increase in the slope of spectral reflectance curve at its absorption edge near 515 nm. It was found that the addition of a small amount of Fe to the parent alloy AP10 markedly increased lightness, L*, and the addition of Sn gave a very light tint of red to the parent alloy. Although red-green chromaticity index a* contributed to chroma to some extent, contribution of yellow-blue chromaticity index b* was much greater in determining chroma in this Pd-free Au-Pt-based multi-component alloys. The present results are expected to be valuable in case color is to be taken into account in designing Pd-free Au-Pt-based high noble dental alloys.

Ion release from experimental Au–Pt-based metal–ceramic alloys

“…To make clear the effects of the inclusion of oxide-forming elements, In/Fe/Sn/Zn, on various properties of the above-mentioned Pd-free PFM alloys, we are performing systematic studies including optical properties of a series of experimental alloys (16,17).…”

Pt-Pd system: Investigation of mechanical properties

“…The addition of palladium to platinum, as alloying element, to change the color of highly noble dental alloys has been the subject of research [12,13]. Thermal stability, mechanical properties and influence of palladium in thin films based on noble metals have been investigated [14][15][16].…”