Ultrasonic and Optical Investigation of Mercury Content Influence on Metrological Properties of Reference Alloy Materials

Abstract

Alloys are a mixture of pure metals. They had to be checked for their quality, production, and performance repeatability according to a standard. Thus, reference material may be obtained. The key novelty of this work is the preparation of a reference non-ferrous alloy material according to standards. It has great importance in the restorative materials. In addition, a novel ultrasonic technique was developed. Poly-methyl-methacrylate delay line was designed to modify the used ultrasonic transducers. Alloy powder of platinum modified non-gamma 2 mixed with different mercury percentages (0.5%, 1%, 1.5%, 2%, 2.5% and 3% weight by weight) at room temperature. According to standards, ultrasonic and optical measurements studied the influence of different levels of mercury in the alloy specimens. Ultrasonic velocities and attenuation measurements were carried out using the pulse echo technique. Ultrasonic velocities served to calculate the elastic properties, then to determine the mechanical behavior of the mixed alloy. Ultrasonic attenuation revealed the microstructure change of the mixed alloy. The number of crosslink density and the ultrasonic viscosity are measured. The changes in the optical constants, absorption coefficient, optical band gap, and Urbach energy were measured using the ellipsometric method. Results showed that the mercury content had a great influence on the mechanical properties and the microstructure of the alloys. In addition, 1, 1.5, and 2.5 % W/W mixed alloys were the most mixture that had homogeneous microstructure and could be used as reference restorative materials. The optimum one was the specimen with a mercury content of 2.5 %.