Alkali Durability of Oxynitride Glass Fibers

Oxynitride glass fibers were drawn from the melt in N₂ atmospheres. The fibers were tested for their alkali durability in 10% NaOH at 96°C for 6 h. The durability is reported as weight loss in mg/cm². The photomicrographs of the fibers before and after testing are presented. Calcium silicate oxynitride fibers have good durability because of a protective surface layer of Ca(OH)₂. Yttria-containing glasses have the best durability among the compositions reported here.