Improved Graphite Materials for Re-Entry Vehicles. Volume III.
Abstract
Processing studies and preliminary material characterization data are described for several types of carbon/carbon composites in which a reinforcement constituent extends in several directions in three dimensions. The principles of 4-directional reinforced nose tip ma-terials are described. The first 7- directional yarn reinfor-cement has been fabricated under this contract. Modifica- tions to a 150 C softening point coal tar pitch were ex-plored, and this pitch was used for the matrix in a 4-D reinforced graphite made from Type 2, PAN precursor, 10,000 filament tow. Although ablation performance and impact resistance (inplate slap) were facorable, the high anisotropy inherent to this fiber system tends to limit mechanical strength. Strength, elastic modulus, and thermal expansion doefficient have been characterized as a function of fiber packing angle in this composite. Limited data on CVD-in-filtrated unidirectional and 4-directional fiber systems has also been obtained. Comparative ablation tests have been performed with a channel flow facility and a miniature high pressure facility, and use of a laser for vaporization screening was explored. Scanning electron microscopy shows that rayon precursor carbon and graphite filaments are oxidized or vaporized preferentially, while PAN-precursor filaments are often etched in relief. (Author-PL)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1970
- Accession Number
- AD0868270
Entities
People
- Edward R. Stover
Organizations
- General Electric