Rheological property and stress development during drying of tape-cast ceramic layers

Journal Article · Sun Dec 01 00:00:00 EST 1996 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1996.tb08099.x· OSTI ID:422730

Lewis, J A; Blackman, K A; Ogden, A L ^[1]; Payne, J A; Francis, L F ^[2]

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1. Univ. of Illinois, Urbana, IL (United States)
2. Univ. of Minnesota, Minneapolis, MN (United States)

Rheological property and stress development of tape-cast ceramic layers derived from nonaqueous alumina (Al{sub 2}O{sub 3})-poly(vinyl butyral) (PVB) suspensions were observed during drying. Casting suspensions exhibited strong shear-thinning behavior, with a low shear Newtonian plateau apparent viscosity >10{sup 2}Pa{center_dot}s. The apparent suspension viscosity displayed a power-law dependence on the Al{sub 2}O{sub 3} volume fraction during the initial stage of drying ({le}30% solvent loss). Stress development, measured by a cantilever deflection method, and parallel weight loss measurements were performed during the drying of tape-cast layers and pure binder coatings. Maximum drying stresses ({sigma}{sub max}) of 1.37--0.77 MPa were observed for plasticized tapes cast at gap heights of 150--400 {micro}m. In contrast, nonplasticized tapes of similar thickness displayed a more gradual stress increase, with {sigma}{sub max} values approximately an order of magnitude higher than their plasticized counterparts. The stress histories of the corresponding binder coatings were quite similar to the tape-cast layers, albeit slightly lower {sigma}{sub max} values were observed. Stresses decayed beyond {sigma}{sub max} with a logarithmic time dependence to an almost constant value of 0.2--0.4 MPa for the plasticized tapes. Based on these observations, process methodologies have been offered to minimize stress development and retention in tape-cast ceramic layers.

• Sponsoring Organization: National Science Foundation, Washington, DC (United States); Minnesota Univ., Minneapolis, MN (United States)
• OSTI ID: 422730
• Journal Information: Journal of the American Ceramic Society, Vol. 79, Issue 12; Other Information: PBD: Dec 1996
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES
30 DIRECT ENERGY CONVERSION
COMPOSITE MATERIALS
CASTING
STRESSES
ALUMINIUM OXIDES
ORGANIC POLYMERS
ELECTRONIC EQUIPMENT
SOLID ELECTROLYTE FUEL CELLS
SLURRIES
VISCOSITY
DRYING
POROSITY
WEIGHT MEASUREMENT
BINDERS
COATINGS
EXPERIMENTAL DATA