Avaliação da influência da temperatura de pré-aquecimento aliado ao ensaio de ciclagem térmica em revestimentos de barreira térmica

Abstract

Around the world the use of gas turbines for energy generation has been growing in recent years. Nowadays, the search for greater efficiency of these machines is carried out, which is mainly aimed at fuel economy, and as a consequence lower environmental impacts. The development and enhancement of thermal barrier coatings properties, known as TBC (thermal barrier coating) is a key element in increasing turbine efficiency. These coatings protect and retard the degradation of gas turbine components at high temperatures, enabling increased turbine working temperature, thereby increasing their efficiency and lifetime. The real capacity of the TBC is still under development. In order to increase the protection properties of thermal barrier coatings, different studies related to the mechanisms of degradation of these materials are carried out. These tests simulate the severe conditions which happens in the gas turbines environment, with the objective of forcing the mechanisms of wear on the coatings studied. This work uses the equipment Burner Rig in the evaluation of TBC coatings. The purpose of this test is to create large temperature differences in the Top Coat (ceramic coating) in reduced time spaces, while the top of the coating is exposed to high temperatures the ceramic metal interface remains at temperatures well below. This temperature gradient promotes stresses that generates nucleation and crack growth in the ceramic. The results obtained with these tests were able to show the differences that the preheating temperatures provoke in the growth of cracks, alteration of morphology and porosity of the thermal barrier coatings. With this, it is possible to minimize the effects of the degradation suffered, increasing the lifetime of the coatings.