LOW COST HETEROGENEOUS DEPOSITION OF OXIDE INTERFACE COATINGS FOR CERAMIC COMPOSITES

Gateway Materials Technology and BIRL-Northwestern University propose to develop a deposition process for oxide coatings on ceramic fibers based on an aqueous chemistry route. Hetreogeneous deposition chemistry (HDC) utilizes precise control of concentration, solubility, and surface area to precipitate particles and costings directly on selected surfaces, based on knowledge of nucleation and growth chemistry. The HDC process offers a number of potential advantages for interface coatings in ceramic composites: a wide range of metal oxide compositions and morphologies; uniform, unbridged coatings in complex weaves and architectures; low temperature processing with minimal environmental concerns; and scalability to continuous processing. Phase I of the SBIR effort will concentrate on assessing and developing the baseline HDC process for three oxide compositions and demonstrating the uniformity and controllability of the coating on Nicalon and Nextel tow, fabric, and 3-D performs.