Surface Treatment of P2O5-BaO-Al2O3-K2O Phosphate Laser Glass

The surface of P2O5-BaO-Al2O3-K2O phosphate glass was modified by using both a chemical etching process and a subsequent high-temperature heat treatment, which can effectively remove the surface defects of phosphate glass and the surface contaminations caused by traditional polishing technology. The process of etching phosphate glass in hydrochloric acid was studied to investigate the etching mechanism and determine the etching optimum conditions. It is found that the etching reactions between hydrochloric acid and glass make the phosphate glass surface smooth while a crystal layer is formed on the glass surface. The optimum etching process is as follows, etching in a 9mol/L HCl solution for 30min. After further heating the glass at 550℃, the crystal layer can be removed as crystal particles on glass surface melt, which results in the increase of the transmittance of glass. The results show that a process combining chemical etching the phosphate glass with subsequent heating treatment is an effective method to improve the surface quality of the phosphate glass.