Fiber Strength Retention of Lanthanum- and Cerium Monazite-Coated Nextel™ 720

Nextel? 720 fibers were coated with LaPO₄ and CePO₄ monazite. The coatings were applied using washed and unwashed rhabdophane sols derived from La(NO₃)₃/(NH₄)₂HPO₄ and a washed sol derived from Ce(NO₃)₃/H₃PO₄. The coatings were cured in-line at 900°–1300°C. Multiple coatings were also applied. Fiber strength was retained after coating with washed sols, but not with unwashed sols. These results are consistent with earlier work on LaPO₄ monazite fiber coatings derived from La(NO₃)₃/H₃PO₄.