Isochronal annealing kinetics and neutron-induced dimensional changes of titanium-doped pyrolytic carbons
✍ Scribed by R.J. Price; J.C. Bokros
- Publisher
- Elsevier Science
- Year
- 1971
- Tongue
- English
- Weight
- 797 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0008-6223
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✦ Synopsis
A series of isochronal 1 hr anneals was conducted on a laminar pyrolytic carbon deposited at 1225°C containing 6.7 wt .% titanium, an isotropic pyrolytic carbon deposited at 2200°C containing 9.7 wt.% titanium, and titanium-free companion carbons. Changes in layer spacing, apparent crystallite height (I>,), density, electrical resistivity, and microhardness were followed. Heterogeneous recrystallization to graphite started in the titanium-doped isotropic carbon at 2300°C and was completed at 25OOY:. 'l'he titanium-doped laminar carbon did not show catalytic recrystallization. The undoped isotropic carbon was not responsive to annealing. The titanium-doped and titallirlrnfree laminar carbons showed a steady increase in I.,. and density and a steady reduction in layer spacing and microhardness over a temperature range from 1400" IO 2800%, but significant reduction in electrical resistivity did not begin unril -.' 18OOY~. 'l-he dimensional changes induced by fast-neutron exposures ~11 to -8 X lo" n/cm" at --(iOO"(: to 125OY; were measured and found to be lower by a f'actor of 3-10 in a catalytically graphitized pyrolytic carbon than in an as-deposited carbon with the same degree of preierred orkilaiion.
Devices and Apphcations,