The Size Effect Of Nuclear Graphite On Mechanical Property

As one of the important part of high temperature gas cooled reactor, the mechanical property and strength distribution of nuclear graphite should be seriously treated. The property of graphite materials is related to specimen size.This paper mainly studied the size of the influence of the tensile strength, bending strength, compression strength and fracture toughness.The results showed:(1) The flexural strength decreased as the specimen size increased, that was the obvious size effect phenomenon. The flexural strength decreased as the support span length increased. The 3-point flexural strength was bigger than 4-point flexural strength. In addition, the Weibull size effect equation was used to verify experimental results. (2) The tensile strength had the size effect phenomenon in certain cases. (3) The compressive strength didn’t have the size effect phenomenon. (4) The fracture toughness had the size effect phenomenon in certain cases. Furthermore, SENB method is more suitable than CN method for testing the fracture toughness of nuclear graphite,and IM method can’t test the fracture toughness of nuclear graphite.The nuclear fault is brittle fracture. Fractures often occur on crystals of binder dipping glue, and less on grains.Generally, there are a lot of flaws like pinholes in graphite crystal, and fracture faces of samples always develop from them. The improvement of mechanical properties can consider to further improve the ratio of graphite aggregate particle size, and use the better performance of binder and impregnant.