Effect of low-dose reactor radiation on the dynamic mechanical behavior of pyrolytic graphite

✍ Scribed by J.J. Brennan; D.E. Kline

• Publisher: Elsevier Science
• Year: 1967
• Tongue: English
• Weight: 776 KB
• Volume: 5
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(67)90072-3

✦ Synopsis

The dynamic mechanical behavior of pyrolytic graphite (PG) (deposited at 2200°C) has been investigated as a function of reactor radiation dose up to 1.8 x 10" nvt (fast). Studies made from about 100°K to 800°K at frequencies near 2000 c/s indicate that the dynamic modulus of as-received PG decreases over this temperature range a few percent. A relaxation peak (&-'z. 10m3) appears near 240°K.

Irradiation to 1.8 x 1O1' nvt (fast), results in a non-linear increase in modulus with dose to about 5.5 per cent and in a pronounced modulus inflection near 240°K. Relaxation processes are also evident near 380°K and 700°K in the irradiated samples. Upon retesting of irradiated samples, which had been exposed to temperatures of 700°K to 800°K during the prior test runs, the modulus recovered to approximately as-received values, but the 240°K inflection anomaly became more prominent. Annealing studies indicate that the modulus recovery depends upon temperature and time. Exposure to high test temperatures appears to eliminate the 380°K post-irradiation peak but leaves the 700°K process almost undisturbed.

The 380°K peak also disappears with time at constant temperature (near 380°K). An attempt is made to interpret some of the experimental results and to correlate the observations with irradiation effects in graphite as reported in the literature.