Effect of Bn Interfacial Coating on the Strength of a Silicon Carbide/Silicon Nitride Composite

Abstract

Boron nitride has been identified as a good fiber/matrix interface coating for SiC fibers in a Si3N4 matrix. Boron nitride thin films prepared from BCl3 and NH3 at 1000°C and from B2 H6 and NH3 at 550°C were deposited on SiC (Nicalon®) cloth in a low pressure chemical vapor deposition reactor. The coating thickness was varied from 0.1 μm up to 4 μm. Six layers of cloth for each coating thickness were incorporated into a chemical vapor infiltrated matrix of amorphous Si3N4.Flexural strength data and composite toughness were obtained from three-point bend tests. Scanning electron microscopy and metallographic analysis of fracture surface morphology were used to determine the failure mode.

Influence of Isothermal Chemical Vapor Deposition and Chemical Vapor Infiltration Conditions on the Deposition Kinetics and Structure of Boron Nitride

“…20 It has been successfully used in various composite systems. [21][22][23][24][25][26][27][28][29] Particular attention has been given to the interfacial zones, in terms of chemistry and microstructure. [26][27][28][29] These studies revealed that many interfacial carbon-and/or SiO 2 -rich sublayers can be present between the SiC fibers (Nicalon™ (Nippon Carbon, Tokyo, Japan) or Tyranno™ (UBE Industries, Yamaguchi, Japan)) and the BN film.…”