Abstract
Some brazing filler metals containing titanium were brazed to sapphire plates under some brazing conditions, in order to investigate the cause of discoloration at the brazed surface. The differences of discoloration at the brazed surface were observed with a video-microscope from the reverse side of the brazed plane, and the brazed sapphire surfaces were examined by SEM after removing the brazing filler metals by dissolution using nitric acid and hydrofluoric acid. According to the SEM observation of brazed surfaces, the discoloration at the brazed surface increased with the increase of surface roughness caused by erosion of sapphire. The Brilliant-cut rubies were brazed to metals at the pavilion area under some brazing conditions with different erosion depth, and the discolorations at the brazed area were observed from the table-plane side. It was found that the discoloration at the brazed area is suppressed with the decrease of ruby erosion at the brazed surface.
