Melt Drawing/Coating of Oxide Fibers for Composite Materials Applications.
Final rept. Oct 95-Feb 96,
CONTAINERLESS RESEARCH INC EVANSTON IL
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Undercooled oxide melts achieved a melt viscosity sufficient to draw mullite fibers whose chemical, microstructural, and mechanical properties were measured. Tensile strengths were 5.61 - 0.71 GPa 810 - 100 KSI for as-drawn, amorphous fibers of 10-40 micron diameter and up to 1.0 GPa after crystallization by annealing in air. Melt drawing of YAG fibers was also demonstrated. Fiber coatings were formed by pulsed excimer laser ablation. Push-out tests on coated fibers imbedded in a ceramic matrix gave small values of the debonding shear strength, tau d 25 MPa, for fibers coated with 2 MgO-SiO2 enstatite which provided an interphase-weakening effect. Somewhat larger values of tau d were obtained for LaPO4 coated fibers which provide an interface-weakening effect. Mullite fibers with YPO4 coatings exhibited chemical and dimensional stability during a 2 hour anneal in an aluminum oxide matrix at 1500 deg C. The fiber-pulling process has potential for scale-up to produce high quality oxide fibers at less than 100 per pound.
- Test Facilities, Equipment and Methods