The effect of spark plasma sintering on lithium disilicate glass-ceramics

Fatima Al Mansour; Natalia Karpukhina; Salvatore Grasso; Rory M Wilson; Mike J Reece; Michael J Cattell

doi:10.1016/j.dental.2015.07.001

The effect of spark plasma sintering on lithium disilicate glass-ceramics

Dent Mater. 2015 Oct;31(10):e226-35. doi: 10.1016/j.dental.2015.07.001. Epub 2015 Jul 23.

Authors

Fatima Al Mansour¹, Natalia Karpukhina², Salvatore Grasso³, Rory M Wilson³, Mike J Reece³, Michael J Cattell⁴

Affiliations

¹ Centre for Adult Oral Health, Institute of Dentistry, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Turner Street, Whitechapel E1 2AD, UK.
² Dental Physical Sciences, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Mile End Road, E1 4NS, UK.
³ School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, E1 4NS, UK.
⁴ Centre for Adult Oral Health, Institute of Dentistry, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Turner Street, Whitechapel E1 2AD, UK. Electronic address: m.cattell@qmul.ac.uk.

PMID: 26211698
DOI: 10.1016/j.dental.2015.07.001

Abstract

Objectives: To evaluate the effects of spark plasma sintering (SPS) on the microstructure of lithium disilicate glass-ceramics.

Methods: IPS e.max CAD glass-ceramic samples were processed using spark plasma sintering (SPS) and conventionally sintered (CS) as a comparison. Specimens were sintered at varying temperatures (T1: 840°C, T2: 820°C, T3: 800°C), heating rates (HR1: 150°C/min, HR2: 300°C/min, HR3: 500°C/min) and pressures (P1: 15MPa, P2: 50MPa, P3: 70MPa). IPS e.max Press glass powder samples were densified at 750 and 800°C (50 or 200MPa pressure). Samples were characterized using XRD, HTXRD, and SEM and quantitative image analysis.

Results: There was a significant increase in median crystal size (MCS) between the CS and the SPS T1 groups. A statistical difference (p>0.05) in MCS between SPS T1 and SPS T2 groups was observed. The SPS HR3 sample produced a smaller MCS than the CS, SPS HR1 and HR2 groups (p<0.05). The SPS P3 sample had a reduction in MCS compared with the CS group (p<0.05). XRD of the SPS samples revealed major lithium disilicate/lithium metasilicate phases and minor lithium orthophosphate and cristobalite/quartz phases. Densified IPS e.max Press glass samples resulted in fine fibrils or graduated lithium disilicate crystals.

Significance: The effects of SPS were used to refine the microstructure of IPS e.max CAD lithium disilicate glass-ceramics. Densification by SPS of IPS e.max Press glass resulted in textured and fine nano-crystalline microstructures. SPS generated glass-ceramic microstructures may have unique properties and could be useful in the production of CAD/CAM materials for dentistry.

Keywords: Crystallization; Glass-ceramic; Lithium disilicate; Microstructure; Spark plasma sintering; X-ray diffraction.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Ceramics / chemistry*
Computer-Aided Design
Crystallization
Dental Materials / chemistry*
Dental Porcelain / chemistry*
Dental Stress Analysis
Elastic Modulus
Hardness
Hot Temperature
Materials Testing
Surface Properties

Substances

Dental Materials
lithia disilicate
Dental Porcelain
Glass ceramics