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Uniform TitleMicrostructure-property relaltionship in silicon carbide armor ceramics
NameDemirbas, Memduh Volkan (author), Haber, Richard (chair), Niesz, Dale (internal member), Cannon, W (internal member), Pujari, Vimal (outside member), Rutgers University, Graduate School - New Brunswick,
Degree Date2008-05
Date Created2008
SubjectCeramic and Materials Science and Engineering,
Silicon carbide,
Armor,
Ceramics
DescriptionDefects are one of the factors that show a negative effect on the ballistic performance. Uniform microstructures with a low percentage of well distributed porosity could possibly demonstrate high ballistic strength; therefore, it is of interest to estimate the parameters that define the spatial arrangement of defects. This aspect of microstructures was investigated in a variety of silicon carbide ceramics ranging from off-density sintered samples to high density hot-pressed armor grade samples.
The spatial distribution of defects was examined by various techniques including nearest neighbor distance distributions, tessellation analysis, and pair correlation functions. Random distributions were observed for most of the samples with some degree of clustering. Hardness was selected as a mechanical property to correlate with microstructural findings. Hardness contour maps were constructed by indenting samples with a statistically significant number of indents per load to see the variation in terms of location. The large number of indents allowed for Weibull analysis to be used to examine the spread in the data and to test spatial variability. A high degree of correlation was obtained between microstructural parameters and hardness/Weibull modulus values. Smaller defect sizes and homogenous distribution of defects were shown to provide higher hardness values.
A sintered SiC tile was examined using ultrasound to determine high and low amplitude regions in C-scan image maps. Serial sectioning was performed on diced samples from these two regions. Although no significant difference was observed in terms of density and average defect size, statistical tests showed that the difference in the largest defect size detected in low amplitude and high amplitude regions was significant. Clusters of defects were also identified in the samples from the low amplitude regions. The signal loss that was observed in C-scans maps could partially be attributed to these results.
A particularly high degree of correlation was shown between average defect size, spatial distribution parameters and hardness data. These findings exhibit the strong effect of microstructure on the quasi-static properties and may affect ballistic performance.
The spatial distribution of defects was examined by various techniques including nearest neighbor distance distributions, tessellation analysis, and pair correlation functions. Random distributions were observed for most of the samples with some degree of clustering. Hardness was selected as a mechanical property to correlate with microstructural findings. Hardness contour maps were constructed by indenting samples with a statistically significant number of indents per load to see the variation in terms of location. The large number of indents allowed for Weibull analysis to be used to examine the spread in the data and to test spatial variability. A high degree of correlation was obtained between microstructural parameters and hardness/Weibull modulus values. Smaller defect sizes and homogenous distribution of defects were shown to provide higher hardness values.
A sintered SiC tile was examined using ultrasound to determine high and low amplitude regions in C-scan image maps. Serial sectioning was performed on diced samples from these two regions. Although no significant difference was observed in terms of density and average defect size, statistical tests showed that the difference in the largest defect size detected in low amplitude and high amplitude regions was significant. Clusters of defects were also identified in the samples from the low amplitude regions. The signal loss that was observed in C-scans maps could partially be attributed to these results.
A particularly high degree of correlation was shown between average defect size, spatial distribution parameters and hardness data. These findings exhibit the strong effect of microstructure on the quasi-static properties and may affect ballistic performance.
NotePh.D.
NoteIncludes bibliographical references (p. 210-219).
Genretheses
Persistent URLhttp://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17300
LanguageEnglish
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.