Electrochemical vapor deposition of yttria-stabilized zirconia

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6956023

Carolan, M F

Electrochemical vapor deposition (EVD) is the leading technology to produce thin, gas tight films of yttria-stabilized zirconia over porous substrates. Such films are necessary for the construction of efficient solid oxide electrolyte fuel cells and steam electrolyzers. The critical initial step of the EVD process is the chemical vapor deposition of electrolyte on porous substrates. Pore closure occurs at the metal chloride face of the substrate. A model developed to explain these phenomena shows that the CVD reaction of ZrCl{sub 4} and H{sub 2}O is best described by a reaction which is zero order in water and positive order in metal chloride. A single dimensionless parameter, the Thiele modulus, describes the film penetration depth, final pore radius profile and the time for pore closure. High Thiele moduli are desirable to minimize both pore narrowing and the time for pore closure. The growth rate of the film during of EVD phase follows a parabolic rate law, indicating that film growth is limited by transport through the film. Films grow at the same yttrium-to-zirconium ratio as found in the reactant gases.

• Research Organization: California Univ., Berkeley, CA (USA)
• OSTI ID: 6956023
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
CHALCOGENIDES
CHEMICAL COATING
CHEMICAL REACTIONS
CHEMICAL VAPOR DEPOSITION
CHLORIDES
CHLORINE COMPOUNDS
DEPOSITION
ELECTROLYTES
FILMS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
MATERIALS
METALLURGICAL EFFECTS
OXIDES
OXYGEN COMPOUNDS
POROUS MATERIALS
SUBSTRATES
SURFACE COATING
TRANSITION ELEMENT COMPOUNDS
WATER
YTTRIUM COMPOUNDS
YTTRIUM OXIDES
ZIRCONIUM CHLORIDES
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES