Avaliação do comportamento dos revestimentos de carbeto de tungstênio e carbeto de cromo via HVOF frente à fadiga térmica

Abstract

Thermal fatigue is a failure mode that occurs in materials and equipment subject to sudden and cyclical changes in temperature. Aiming for longer parts life, the ceramic coating is inserted as an alternative to prolong the service life of the machinery, in order to increase productivity and reduce maintenance costs. The ceramic coatings of Chromium Carbide (CrC) and Tungsten Carbide (WC) are deposited by thermal spraying via High Velocity Oxygen Fuel (HVOF), whose function is increasing the resistance to thermal fatigue. Therefore, the present study had as objective to evaluate the resistance to thermal fatigue, of ceramic coatings, aiming at the use of the coating that best suits the thermal shock environment. For this, the thermal cycling test was carried out, evaluating the porosity, micrographs, microhardnesses and the thermal stresses of the CrC, WC and steel 1020 coatings were analyzed, comparing them. From the tests carried out it can be observed that the CrC coating presented a better performance, resisting the thermal shock, in comparison to the WC which the coating completely left the substrate. In addition to presenting lower inclusion levels, the two coatings also had lower hardness values after the test.