Enhancing permeability and porosity of ceramic shells for investment casting through pre-wetting

Noel O'Sullivan, Joseph Mooney, David Tanner

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, a method known as pre-wetting is applied between the multilayer ceramic investment casting shells to enhance porosity and permeability while sustaining flexural strength. Pre-wetting consists predominately of an aqueous silica binder that improves inter-coat bonding in complex areas. Porosity is developed where the pre-wetting is applied due to the evaporation of the aqueous phase. Results indicate that as porosity increases, both green and fired flexural strength reduce on average by 8.7 - 15.6 % and 18.7 - 28.5 %, respectively, whereas hot strength is increased by 20 - 25 %. Permeability increased by a factor of two when pre-wetting was applied between intermediate coatings and displayed a stepwise increase in intrusion volume in the high-pressure regime through mercury intrusion porosimetry. X-ray microtomography coupled with pore network modelling provided a validation of the increase in the permeability constant. Gas adsorption methods revealed the presence of micropores through the alpha-s method when bilayers of pre-wetting solution were applied.

Original languageEnglish
Pages (from-to)411-422
Number of pages12
JournalJournal of the European Ceramic Society
Volume41
Issue number16
DOIs
Publication statusPublished - Dec 2021

Keywords

  • Ceramic shell
  • Investment casting
  • Modulus of rupture
  • Permeability
  • Porosity
  • Pre-wetting
  • Primary facecoat

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