ВПЛИВ ВИСОКОЇ ТЕМПЕРАТУРИ НА ЗМІНУ КОЛЬОРУ У МІЦНИХ ГІРСЬКИХ ПОРОДАХ

Abstract

Methodology. The samples were prepared in the form of 15x15 cm cubes. One side was polished, while the others were sawn. The samples were subjected to thermal heating in a muffle furnace at temperatures of 200, 400, 600, and 800 °C. The stone samples were heated slowly at a rate of 4 °C per minute. Upon reaching the desired temperature, the stones were maintained at that temperature for 1 hour. After heating, the stone samples were slowly cooled in the muffle furnace for 24 hours. Each experiment included three samples of stone of each type. Images of the natural stone were scanned before and after heating, and then processed using software to obtain quantitative color change indicators in the CIELab system. Results. With increasing temperature, the surface of Leznikiv granite became lighter due to a change from a saturated dark-red color to a light-red color and the appearance of white mineral spots. When heated, Maslav granite lost its green color, and brown spots appeared in place of the green. Heating the surface of gabbro resulted in the appearance of brown spots, with the area of spots increasing as the temperature increased. Labradorites also developed brown spots, which increased in size with higher temperatures. Additionally, the iridescence of labradorite disappeared with increasing temperature, and the surface acquired a lighter shade. Scientific novelty. For the first time, a correlation was established between the propagation speed of ultrasonic waves in Leznikiv, Maslav granites, Bukin gabbro, and Kateryniv labradorite when heated to 800 degrees. Leznikiv granite exhibited the smallest loss in ultrasonic wave speed, while Maslav granite showed the highest loss. Comparing labradorite and gabbro, labradorite had the least loss in ultrasonic wave speed when heated. Practical Significance. The findings of this study provide the ability to predict color changes in natural stone when subjected to heating.