Cyclic high temperature oxidation of HFPD thermal sprayed CoNiCrAlY coatings under simulated gas turbine and furnace environments

Abstract

CoNiCrAlY powders were thermal sprayed using the high frequency pulse detonation (HFPD) method onto AISI 310 austenitic stainless steel samples. The cyclic oxidation behaviour of these coatings at 800 and 1000uC in simulated gas turbine and standard atmosphere environments was experimentally determined. Austenitic AISI 310 was used as a reference. Composition and morphology of surface phase were evaluated using X-ray diffraction and scanning electron microscope techniques. Oxidised HFPD CoNiCrAlY coatings have always been characterised by the formation of a continuous and highly protective alumina layer. In contrast, the protection of the chromium oxide layer generated on the austenitic AISI 310 under the same operating conditions is much less effective and a degraded region near to the oxidised layer has been observed at the highest temperatures. Moreover, cracks appear in the chromium oxide layer when it is submitted to high thermal gradients, as a consequence of thermal stresses.

The influence of pyrolysing Al2O3 precursor on the high temperature properties of the YSZ-Al2O3 composite coating

“…Improvement in power output and thermal efficiency of the gas turbine depends on increase of turbine inlet temperature (TIT). However, high temperature also increases the oxidation and hot corrosion rate of the metallic components, that have been coated by thermal barrier coatings (TBCs) [1,2]. The low thermal conductivity of TBCs leads to the reduce in the heat transferred to the substrate, allowing the turbine to operate at much higher gas temperatures than the melting point of the substrate material, Thereby improving engine efficiency and performance [3].…”

Microstructure and Hot Corrosion Properties of Laser Cladding of a Co-Base Alloy on the Leaf Surface of Gas Turbine

“…Thus the alloys used as turbine components must be oxidation, corrosion, fatigue, and wear resistant, and be stable in microstructure at high temperatures. In recent years, surface modification such as electric arc spraying, hot spraying, plasma spraying and laser surface cladding or alloying have been reported [1][2][3][4][5][6]. CoCrW CoCrBSi and MCrAlY alloys are often chosen as the protective coating materials.…”