Rheological Property and Stress Development during Drying of Tape‐Cast Ceramic Layers
1996; Wiley; Volume: 79; Issue: 12 Linguagem: Inglês
10.1111/j.1151-2916.1996.tb08099.x
ISSN1551-2916
AutoresJennifer A. Lewis, Kimberly A. Blackman, Andrea L. Ogden, James A. Payne, Lorraine F. Francis,
Tópico(s)Rheology and Fluid Dynamics Studies
ResumoRheological property and stress development of tape‐cast ceramic layers derived from nonaqueous alumina (A1 2 O 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 2 Pa . s. The apparent suspension viscosity displayed a power‐law dependence on the A1 2 O 3 volume fraction during the initial stage of drying (<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 (σ max ) of 1.37‐0.77 MPa were observed for plasticized tapes cast at gap heights of 150‐400 μm. In contrast, nonplasticized tapes of similar thickness displayed a more gradual stress increase, with σ 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 σ max values were observed. Stresses decayed beyond σ 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
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