Abstract/Details

Effect of sputter deposited YSZ thin films on the fracture behavior of dental bioceramics


2008 2008

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Abstract (summary)

The fracture behavior of dental bioceramic materials was evaluated under physiologic conditions when modified by yttria stabilized zirconia (YSZ) thin film deposition. It was hypothesized that changing the YSZ thin film properties will produce a significant enhancement in the strength of bioceramic materials, ultimately promoting a more fatigue resistant construct. Porcelain, alumina, and zirconia were evaluated in terms of dynamic fatigue for an initial characterization of their fracture behavior. Data showed that strength degradation occurred in all three materials, most drastically in porcelain. Initial strength measurements, focused on depositing YSZ thin films on three unique substrates; porcelain, alumina, and zirconia, were carried out. A significant increase in strength was observed for alumina and porcelain. Since strength alone is not enough to characterize the fracture behavior of brittle materials, coated specimens of porcelain and zirconia were subjected to dynamic fatigue and Weibull analysis. Coated YSZ porcelain specimens showed a significant increase in strength at all tested stressing rates. YSZ coated zirconia specimens showed similar strength values at all stressing rates. The effect of film thickness on porcelain was also evaluated. Data demonstrated that film thickness alone does not appear to control increases in the flexural strength of a modified substrate. It is expected that deposition induced stress in YSZ sputtered films does not change with film thickness. However, a thicker film will generate a larger force at the film/substrate interface, contributing to delamination of the film. It was clear that in order to have a significant improvement in the fracture behavior of porcelain, changing the thickness of the film is not enough. The columnar structure of the YSZ films developed seems to favor an easy path for crack propagation limiting the benefits expected by the coating. The effect of a multilayered film, composed by brittle/ductile (YSZ/parylene) layers on porcelain was investigated. Strength measurements of porcelain bars coated with a single layer of parylene, YSZ, and YSZ+parylene were different than the uncoated group. The greatest increase in strength was shown when a multilayered structure was applied. SEM analyses show that crack deflection occurs. The effect of a laminate film structure was also evaluated in terms of dynamic fatigue. However, the fatigue behavior decreased for the coated group. It is speculated that the residual stress profile and deposition conditions of this film may have influenced crack propagation.

Indexing (details)


Subject
Dental care;
Materials science
Classification
0567: Dental care
0794: Materials science
Identifier / keyword
Health and environmental sciences; Applied sciences; Bioceramics; Ceramic materials; Dental porcelain; Fracture; Strength; Surface coating; Thin films; YSZ
Title
Effect of sputter deposited YSZ thin films on the fracture behavior of dental bioceramics
Author
Teixeira, Erica Cappelletto Nogueira
Number of pages
155
Publication year
2008
Degree date
2008
School code
0153
Source
DAI-B 69/07, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780549669876
Advisor
Thompson, Jeffrey Y.
University/institution
The University of North Carolina at Chapel Hill
Department
Materials Science
University location
United States -- North Carolina
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3315635
ProQuest document ID
304531956
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/304531956
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