Measurement and Validation of Coefficient of Thermal Expansion of Graphite IG-110 under Compressive Stress

Coefficient of thermal expansion（CTE） of nuclear graphite IG-110 under compressive stresses was measured with the strain gauge method,and the corresponding effects of stresses on the CTE of IG-110 were analyzed.Results indicate that the strain gauge method is feasible and reliable in the CTE measurement of IG-110.Compressive stresses have significant effects on the CTE of graphite IG-110.Compared with those of the unloaded specimens,CTE parallel to the loading direction of specimens increases from 3.71×10^-6 K^-1 to 4.20×10^-6 K^-1,4.41×10^-6 K^-1 and 4.78×10^-6 K^-1 for compressive stresses of 20,30,40 MPa which increases by about 13.2%,18.9% and 28.8%,respectively.Meanwhile,CTE perpendicular to the loading direction de-creases from 4.03×10^-6 K^-1 to 3.80×10^-6 K^-1,3.79×10^-6 K^-1 and 3.75×10^-6 K^-1 which decreases by around 5.7%,6.0% and 6.9%,respectively.CTE changes of nuclear graphite under stresses are probably due to the opening or closure of micro-cracks induced by stress in graphite.