THERMAL CYCLING AND ISOTHERMAL TESTS ON BLACK-COATED SPECIMENS

Thermal cycling and isothermal tests were performed on AISI 316 L(N) a ustenitic steel with different types of black coating. The adhesion an d the fatigue life of the coatings, as well as the fatigue of the base material were investigated. The tests were performed in different tes t rigs, using tubes and circular discs. The discs were subjected to cy clic heating on the coated side, using an Ar + He + 1% H-2, flame in a plasma spray facility. The tubes, coated on the outside, were inducti on heated. The temperature ranges typical for first wall applications were about 150-430 degrees C on the discs and 80-435 degrees C for the tubes. Isothermal strain-controlled uniaxial tests on coated tubes ha ve been carried out as a base comparison for the thermal cycling exper iments. In this report, the test rigs are described and the results of the tests are presented. For the tubes, the adhesion of the coatings up to high loadings was surprisingly good. Likewise, no accelerated fa tigue of the base material was observed to be caused by the coatings. For the discs, nearly all the coatings survived 10000 load cycles.