Pore Characteristic of Natural and Inorganic Binder Filled Turquoises Based on Gas Adsorption and Scanning Electron Microscope Analysis

Turquoise is a porous gem material, and the porosity can directly affect its physical properties, such as colour, luster, durability, etc., thus affecting the quality of the turquoise. Therefore, the research works on the porosity of turquoise is crucial, and the gas adsorption method can measure the distribution characteristics of mesopores (2-50 nm) and pores of different pore sizes in turquoise. In this paper, the pore characteristics of inorganic binder filled turquoise before and after treatment were comparatively studied by using Bet automatic gas adsorption instrument and scanning electron microscope; the gas adsorption test showed that the specific surface area and pore volume of turquoise after filling treatment were changed to some extent, and the adsorption and desorption curves belonged to the curves of class Ⅲ without hysteresis return line; the average pore size distribution graph showed that the pores of all levels of turquoise after filling treatment were reduced to some extent. The average pore size distribution diagram showed that the pores of turquoise were reduced to some extent, and the large pores were filled into small pores by inorganic binder filling, and the phenomenon of smaller pores being eroded into large pores also occurs during the treatment process; the results of scanning electron microscope study showed that there were large changes in the microcrystalline aggregate morphology, crystal particle characteristics and porosity structure of turquoise before and after the treatment; combined with the calculation, the surface porosity of turquoise samples treated by inorganic filling was significantly reduced, and it was found that the pores in turquoise after treatment were closed at one end and do not penetrate, which were consistent with the pore shape characterized by the adsorption and desorption curves; the obvious difference in the microscopic morphology can be used as one of the bases to distinguish the inorganic binder filled turquoise from natural turquoise.