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Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6063 tion. With this heating method, the center portion of the reaction Monoclinic ZrO 2 was deposited on several metallic and chamber (ϳ5 cm length) could be rapidly heated up to a peak ceramic substrates by reacting ZrCl 4 , CO 2 , and H 2 at temtemperature of 1100ЊC with a relatively uniform temperature peratures of 800؇ to 1050؇C. Ni substrates reacted signifidistribution (within Ϯ25ЊC). A K-type thermocouple was used to cantly in the ZrO 2 coating environment since the coating measure the temperature at the center region of the reactor. was porous and contained a considerable amount of Ni. InThe flow rates of Ar, Cl 2 , CO 2 , and H 2 (99.995%, Alphagaz, contrast, the coating deposited on SiC and aluminoborosiliMorrisville, PA) were controlled using mass flow controllers cate fibers was highly crystalline, faceted, and dense without (1259B, MKS, Andover, MA). The pressure of the reactor was any apparent interaction with the substrate materials.controlled using a mechanical vacuum pump and a solenoid flow valve (248A, MKS) interfaced with a pressure controller (250B,

1997corrosion protection, metal coating, protective coatings corrosion protection, metal coating, protective coatings V 1550 -310Preparation and Characterization of Chemically Vapor Deposited ZrO2 Coating on Nickel and Ceramic Fiber Substrates.-ZrO2, an important ceramic coating material for high-temp. structural applications, is deposited on several metallic and ceramic substrates by reacting ZrCl4, CO2, and H2 at temp. of 800-1050 • C. The Ni substrate significantly reacts with the deposition vapor resulting in porous coatings with considerable amounts of Ni. In contrast, coatings on SiC and aluminoborosilicate fibers are highly crystalline, faceted, dense and show no interactions with the substrate material. -(BORST, M. A.; LEE, W. Y.; ZHANG, Y.; LIAW, P. K.; J. Am. Ceram.