Evaluation of the mechanical behaviour of Cr 2O 3 coating film under tensile load

Abstract

In a fusion blanket, the use of a ceramic film coated on structural materials has been considered for improvement of tritium permeability and compatibility of the structural materials with the tritium breeder and neutron multiplier. The chemical densified coating method was selected as a ceramic coating method, because it was able to form film with no open porosity on both the outer and the inner surfaces of a tube. Structural material with a ceramic coating film experiences some stress due to mechanical and thermal load. Therefore it is necessary to evaluate the mechanical characteristics of the coating film to establish an analytical design method and confirm the design criteria of the coated structure. From such a viewpoint, the load and strain on structural material with ceramic coating film under tensile load were measured, and compared with the results of elastic—plastic analysis with a two-dimensional model. In this test, the main component of the ceramic coating film was Cr 2O 3, and 316SS stainless steel was used as the substrate material. From the results of tensile tests on 316SS with a Cr 2O 3 film, elastic performance was observed up to 0.5% strain, and its tensile load was larger than that on uncoated 316SS. Above 0.5% strain, the tensile load was decreased, and then approached tensile load on uncoated 316SS gradually by peeling of the Cr 2O 3 film. For evaluation of the mechanical behaviour of Cr 2O 3 film under tensile load, the load and strain behaviour of 316SS with Cr 2O 3 film was calculated by elastic—plastic analysis with a two-dimensional model using the results of this tensile test. From this result, it was found that the relation between tensile load and strain on 316SS with Cr 2O 3 film could be simulated by elastic—plastic analysis with the two-dimensional model. In the future, the relation between tensile load and strain on different substrates with Cr 2O 3 film under tensile load will be measured and compared with results calculated by the same analytical method.