Desarrollo de revestimientos de sílice para el proceso de microfundición de joyería con pre-engaste de esmeraldas

The possibility of implementing natural emeralds to the stone in place technique in the manufacture of jewelry was evaluated using two silica samples, one commercial and other developed with natural silica sand, both thermally stabilized at 350 °C. Raw materials and blend performances were characterized by X-ray diffraction, scanning electron microscopy and differential scanning calorimetry and thermo-gravimetry, as well as through compression strength, permeability and thermal shock resistance tests. The sand/gypsum mixture with 68/32 ratio and the addition of 50 wt% of water was selected as the most suitable to obtain the new investment, as well as 38% water for commercial investment. Finally, microcasting tests were carried out with a low melting point gold alloy (398 °C) and simulation tests of this process were performed using the Solidcast^® and Flowcast^® software programs, it was observed full capacity of the alloy to fill the molds, as well as a minimum affectation of the emeralds.