Abstract The operating temperature of the combustion chamber of heavy-duty gas turbines has been continually increased in order to improve engine power and efficiency. Part of this improvement is due to the use of ceramic thermal barrier coatings (TBCs), which reduce thermal flow from the combustion gas to the metallic structural part of the components. The most traditional deposition technique for bond coats on combustion chamber components is Air Plasma Spray; whereas this technology is the optimum one for ceramic coatings, due to air entrapment in the plasma jet significant oxidation of Al is produced during bond coats deposition. The thermal design of a thick porous TBC able to reduce the heat flow to the minimum allowable by the materials temperature limits is performed. Paper includes a German-language abstract.

Abstract In the graded structure, the material, which has a higher coefficient of thermal expansion and good strength (YSZ), is applied in areas where high thermal stresses occur and where crack growth reaches critical values. A material with outstanding high temperature stability was used on the outer surface, where the temperatures during use can exceed the maximum temperatures for long-term use of YSZ. This article describes the manufacturing process of these structures by plasma spraying with a double injector system. The microstructure of these layers is described in detail. Thermal cycling tests with surface temperatures above 1200 deg C are carried out on these graded and stepped WDS systems. The results indicate a considerable increase in service life compared to the non-graded structures, which leads to the conclusion that this concept is well suited for the application. Paper includes a German-language abstract.

Abstract In this paper, the industrial application study is carried out to optimize the robot-controlled plasma spraying process of the thermal insulation layer for the hot gas flow of a GE-Frame-6B gas turbine. Due to the need for the off-line programming procedure, a precise 3D model of the automated coating system and the workpiece is created. In preliminary tests without a workpiece, basic spraying parameters such as spraying distance and spraying angle are optimized to achieve a sufficient layer quality. In the spray experiments, yttria stabilized zirconia Thermal Barrier Coating is used as the coating material and (NiCr)-6Al (Metco 443NS) as the bondcoat. The microstructure is examined using a light microscope, and microhardness measurements are also carried out. The results of the injection experiments are used to set the injection parameters and the travel path for the real component. Paper includes a German-language abstract.

Abstract This paper discusses the application of electrical insulation on glass ceramic. Morphology of splats, phase transformation, mechanical and electric properties of plasma-sprayed ceramic coatings on glass ceramic are studied. It is observed that the preheating of substrate during deposition of glass ceramic is necessary, since bounding mechanism between coating and glass substrate is mainly of chemical nature. However, high preheating temperature causes also large residual stress in the coating. In order to reduce those, substrate cooling must be activated starting the second deposition step. Further spray parameters such as plasma power and powder feed rate must be also reduced in order to reduce the residual stress in the coating. Paper includes a German-language abstract.

Abstract A composite system that combines different properties of two materials in one composite is the coating of flexible fiber fabrics, with hard and wear-resistant structural materials on the one hand and with functional ceramic surfaces on the other hand. Both layer systems are produced using thermal spraying. In this paper, aramid and mullite light fiber fabrics are coated by atmospheric plasma spraying. To check the suitability of the process for as many technical applications as possible, different ceramic materials are used. Through the additional use of metallic adhesion promoter layers such as AlSi, multi-layer systems with high adhesive tensile strength are implemented. The results show that the use of bio-inert and biocatalytic layer materials, such as titanium dioxide and aluminum oxide, and bioactive materials, such as hydroxyapatite, enables this concept to be used in various areas of biomedical technology. Paper includes a German-language abstract.

Abstract In this paper, a quantitative model for determining the viscous behavior of two-phase particles when they hit the substrate is derived and used for the production of silicon-nitride composite layers. Plasma spray deposition is carried out using a Sulzer-Metco unit and powder feed system in which the powder is injected into the jet external to the nozzle. Silicon nitride-YAS layers with low melting points are developed so that the YAS matrix successfully protects the silicon nitride from decay. The model is developed from the observed layer behavior and provides a basis for the further development of ceramic-matrix composite layers. Paper includes a German-language abstract.

Abstract Atmospheric plasma-sprayed (APS) thermal barrier coating (TBC) systems have been used successfully for years in the area of novel production as well as revision and repair. The effectiveness with regard to thermal insulation and thermal insulation, which is primarily dependent on the layer thickness, layer porosity, and thermal conductivity of the system, can be significantly increased. Other application criteria such as the thermal shock behavior of the system base material, adhesive layer, and TBC top layer, etc. are reliably met at the same time. Typical TBC material systems used are zirconium oxides stabilized by means of yttrium oxide or other types of stabilization. This article describes the developments in the named areas that lead to an improvement in both the technical behavior and the commercial boundary conditions. Novel types of spray additives as well as novel and further developments in process engineering are discussed. Paper includes a German-language abstract.