Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604187
Title: Lateral drying of ceramic suspensions
Author: Holmes, D. M.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2006
Availability of Full Text:
Full text unavailable from EThOS. Please contact the current institution’s library for further details.
Abstract:
Many ceramic processing routes, such as tape casting, screen-printing and ink jet printing, involve deposition of a suspension of ceramic particles in a prescribed shape on a substrate. As the liquid evaporates from the suspension, the particles pack together and liquid leaves the pores. In water-based suspensions, these processes often occur at fronts that move from the edge to the centre of the drying layer. This is known as lateral drying. As drying proceeds, the body can change shape, residual stresses can develop and cracking can occur. However, existing models cannot predict either the shape changes that occur or adequately explain why the drying layer cracks. To study this, the drying behaviour of layers of alumina suspensions was investigated experimentally. Measurements were made of the movement of lateral fronts, the changes in local thickness and the activity at the surface of the layers, and the cracking behaviour and the dried thickness profiles were studied. By considering the redistribution of liquid at the first lateral front, where particles pack together, an expression for the thickness profile of the dried layers has been derived. Mass loss data, together with the local thickness measurements, suggest that the particles do not come into touching contact at this first front. Instead, a collapse event occurs when the repulsive layers between the particles are overcome. The development of stress in a drying layer is generally attributed to the build-up of capillary pressure at the surface of the body. However, this causes compression of the particle network, despite the constraint to shrinkage imposed by the substrate, and therefore cannot explain why cracking occurs. Here, it is proposed that the driving force for cracking actually arises from the collapse event. This predicts that cracking should occur while the space between the particles is still filled with liquid. This is consistent with the measurements of surface activity and local thickness, and the cracking behaviour observed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.604187  DOI: Not available
Share: