Investigation on cristobalite crystallization in silica-based ceramic cores for investment casting

Kazemi, A ; Sharif University of Technology | 2013

1164 Viewed
  1. Type of Document: Article
  2. DOI: 10.1016/j.jeurceramsoc.2013.06.025
  3. Publisher: 2013
  4. Abstract:
  5. In this work, cristobalite crystallization and its effects on mechanical and chemical behaviour of injection moulded silica-based ceramic cores were investigated. In order to simulate casting process condition, the sintered samples at 1220 °C were also heated up to 1430 °C. Flexural strength test was carried out on both sintered and heat treated samples. Chemical resistance of the cores was evaluated by leaching the samples inside 43. wt% KOH solution at its boiling point. Phase evolution and microstructure were investigated by thermal analyses (DTA and DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical microscopy (OM). Results showed that cristobalite was crystallized on the surface of fused silica grains at about 1380 °C. Flexural strength of the sintered cores was decreased after simulated casting heat treatment due to cristobalite phase transformation. The formed cristobalite on the surface of fused silica grains dramatically decreased the leachability of ceramic cores
  6. Keywords:
  7. Ceramic core ; Crystallization ; Fused silica ; In situ cristobalite ; Leachability ; Casting process ; Cristobalites ; Injection moulded ; Phase evolutions ; Silica-based ceramics ; Sintered samples ; Bending strength ; Ceramic materials ; Investment casting ; Scanning electron microscopy ; Silica ; Sintering ; Thermoanalysis ; X ray diffraction ; Silicate minerals
  8. Source: Journal of the European Ceramic Society ; Volume 33, Issue 15-16 , 2013 , Pages 3397-3402 ; 09552219 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0955221913003257