Mechanical, Chemical and Microstructural Characterization of Monazite-Coated Silicon Carbide Fibers

摘要: Tensile strengths of as-received Hi-Nicalon and Sylramic fibers those having monazite surface coatings, deposited by atmospheric pressure chemical vapor deposition, were measured at room temperature the Weibull statistical parameters determined. The average tensile uncoated 3.19 +/- 0.73 2.78 0.53 GPa with a modulus 5.41 5.52, respectively. monazite-coated showed strength loss approx. 10 15 percent, respectively, compared fibers. elemental compositions coatings analyzed using scanning Auger microprobe energy dispersive X-ray spectroscopy. LaPO4 coating on was approximately stoichiometric about 50 nm thick. extended to depth 100 150 nm. may have been in first 30 40 layer. However, roughness fiber made this profile somewhat difficult interpret. Microstructural analyses done electron microscopy, transmission selected area diffraction. consists fine beta-SiC nanocrystals ranging size from 1 mn embedded an amorphous matrix. is polycrystalline silicon carbide consisting submicron crystallites 300 Small amount TiB2 nanocrystallites (approx. nm) are also present. consisted chain peanut shape particles monazite-(La) structure. two layers. inner layer outer comprised much smaller microcrystalline