Crack growth behavior of encapsulation processed SiC-PMMA particulate composites
The effect of processing on the fatigue crack propagation and fracture toughness of ceramic-polymer composites was investigated. A new process for composite production was developed with homogeneous particle distribution and low residual stress levels in mind. PMMA was uniformly distributed by encapsulating the SiC substrate by means of precipitation polymerization. The encapsulation processed powders were then compacted at temperatures above T{sub g} to form the composite. The encapsulation process was optimized by varying the initial concentrations of the reactants until homogeneous nucleation was suppressed. The coatings were found to be continuous at the SiC-PMMA interface, with particle agglomeration occurring between coated particles. Polymer loadings equivalent to 30 vol % SiC were achieved. Composites of several particle size ranges were tested under cyclic fatigue and static loading conditions. Fatigue growth rates and fracture toughness data display a trend of increasing crack growth resistance with increasing particle size, with encapsulation processed composites outperforming conventionally cast composites in both cyclic fatigue and fracture resistance. The largest K{sub Ic} value was found to be 2.95 MPa(m){sup 1/2}, a factor of 3 increase over un-reinforced PMMA. The roles of crack deflection, shielding, bridging, and pinning in enhancing toughness were discussed in light of crack profile fracture surface details. 65 refs., 30 figs., 2 tabs.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6180093
- Report Number(s):
- LBL-29611; ON: DE91005372
- Resource Relation:
- Other Information: Thesis (M.S.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COMPOSITE MATERIALS
CRACK PROPAGATION
PMMA
SILICON CARBIDES
ENCAPSULATION
FRACTURE PROPERTIES
PARTICLE SIZE
POLYMERIZATION
CARBIDES
CARBON COMPOUNDS
CHEMICAL REACTIONS
ESTERS
MATERIALS
MECHANICAL PROPERTIES
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYACRYLATES
POLYMERS
POLYVINYLS
SILICON COMPOUNDS
SIZE
360603* - Materials- Properties
360601 - Other Materials- Preparation & Manufacture