Abstract
In order to achieve the high efficiencies demand of industrial gas turbine (GT) combined cycle systems, it is necessary to operate the GT with high turbine inlet temperatures. Currently, gas temperatures at the combustor exit are around 1450 ℃, and combined cycle efficiencies of 50percent have been achieved. The use of ceramic coating on the component surfaces to provide a thermal barrier offers even more thermal protection. In this paper, eddy current testing for measurements of the thicknesses of thermal barrier coatings (TBCs) and artificial detects is described, and initial results are presented from measurements made with TBCs produced by air plasma spray and with CoNiCrAlY-type bond coats for flat surfaces.
