Novel Applications of Ceramic Precursors - TiN Coating on Alumina and Functionally Gradient Materials
- PDF / 2,850,098 Bytes
- 12 Pages / 414.72 x 648 pts Page_size
- 33 Downloads / 233 Views
D. SEYFERTH*, C. K. NARULA**, and P. CZUBAROW*** * Department of Chemistry, Rm 4-382, Massachusetts Institute of Technology, Cambridge, MA 02139 ** Department of Chemistry, Ford Motor Company, P.O. Box 2053, MD 3083, Dearborn, MI 48121 "*** Corporate Technology, Raychem Corporation, 300 Constitution Drive, MS 123/6614, Menlo Park, CA 94025 ABSTRACT There are very few demonstrated applications of ceramic precursor technology. Here, we describe two new applications of known ceramic precursors, thin film deposition and the fabrication of functionally gradient materials [FGM]. To demonstrate the thin film deposition, we prepared titanium nitride film on an alumina substrate using (CH3)3SiNHTiCI3 precursor by a single dipcoat-fire cycle. The fabrication of copper and aluminum based FGMs was demonstrated using Nicalon fiber polycarbosilane and poly(methylsilane) precursors as binders and in situ sources of ceramics. INTRODUCTION During the last decade an extensive amount of research has been carried out on ceramic precursors [1]. There are many claims involving the preparation of materials in film, powder, binder, fiber, and whisker forms but there are only a few success stories. For example, some commercially available SiC fibers are manufactured using a polycarbosilane precursor [2], and metal-oxide film deposition has been done via the sol-gel process [1]. In this presentation, we describe the applications of known ceramic precursors in titanium nitride film deposition and in the fabrication ofFGMs. The first application employs a titanium nitride precursor, (CH 3)3 SiNHTiCI3, described by Narula [3]. This precursor is soluble in common organic solvents and has been shown to furnish microcrystalline TiN at 600 'C. Previous attempts to prepare TiN films by ceramic precursor technology resulted in carbon contaminated films. For example, Matsumura prepared TiN films and fibers by the pyrolysis of titanium halide or alkoxide infiltrated polymers containing cyano groups at 1200 'C in nitrogen [4]. Ogino et al. employed titanium alkoxide to prepare films and fibers which were then pyrolyzed in an ammonia atmosphere at > 800 'C [5]. Recently, it has been suggested that preceramic polymers are suitable as binders for ceramic powders in the fabrication of shaped ceramic parts [6]. When such a part is sintered, pyrolysis of the preceramic polymer occurs with minimal evolution of gases to give a high yield of ceramic residue, which is retained in the part [7]. Preceramic polymers have also been used as binders and in situ sources of ceramics in the fabrication of metal matrix composites (MMCs) [8]. In both cases, the utilization of a preceramic polymer does not require a debinding step. The ceramic phases formed in this process are derived from the reaction of the metal and the ceramic precursor yielding, in most cases, metal carbides and silicides. As a natural extension of this work, we have explored the application of ceramic precursors in the fabrication of FGMs. It is important to note that the FGMs are generally fabricated
Data Loading...
