Objective
The objective of HITS is to develop a new generation of thermal barrier coating systems (TBC's) with enhanced thermal insulation capability for the protection of hot section components in three main areas of transport and power generation technology: aero and land based gas turbine blading, gas turbine combustors and diesels. The developments from HITS will bring far reaching benefits to engine weight and performance economics, component lives, reduced exhaust emissions etc. The technical approach is designed around reducing the thermal conductivity of the ceramic insulative layer by optimising both its composition and morphology. The typical industrial targets of the project will be to halve the thermal conductivity of the coatings for the respective applications: for turbine blading (125mm EBPVD1 coatings), a reduction in k = 1.9 W/m.K(1) 0.5 to 0.8 W/m.K for combustors (500 ,um plasma spray coatings), a reduction in x = 0.9 W/m.K(1) 0.4 to 0.6 W/m.K). For diesels (plasma spray, 1mm thick coatings), surface modifiers to block off the ingress of corrodants must be specially developed if a ceramic layer containing up to 40% porosity is to be viable in such a highly corrosive environment.
In the first phase, novel coatings having low thermal conductivity will be designed as a result of: compositional changes to decrease the ceramic intrinsic thermal conductivity, optimisation of the morphological architecture (pore distribution, microcrack network, column arrangement) of the ceramic coating with the help of a modelling approach, These innovative coating combinations will then be produced after having established the correlation between process variables and coating morphology.
In a second phase, promising candidates will be down selected depending on the industrial process feasibility and by characterizing other coating properties critical to TBC usage (e.g. high temperature microstructural stability and thermal strain tolerance).
In the last phase, the best coating systems identified above will be deposited on real components specially designed to take advantage of the presence of the new low conductivity TBC's. The coated components will perform engine testing in order to demonstrate both the manufacturing capability of and the achieved benefits from a new generation of thermal barrier coatings made in Europe. A new consortium has been established, comprising manufacturers and developers of turbine (SNECMA, Volvo) and diesel engines (Kvernes Technology), coating suppliers in EB PVD (Interturbine) and plasma spray (Sulzer) technologies, institutes/universities specialized in TBC deposition and development (DLR, JRC, RWTH) and an institute specialized in numerical modelling of materials and their physical properties (ONERA), supported by the high temperature processing capability of EB PVD ingots at the University of Leoben. This consortium, composed of coating suppliers, coating users and science base institutes in materials and processes, is ideally tailored to ensure both the technical success of the project and the rapid implementation of the newly developed coatings in European industry.