The main focus of this study is sealed zirconia-based thermal barrier coatings produced by plasma spraying. AEM examinations conducted on phosphate-sealed Y 2 O 3 -ZrO 2 coatings and orthophosphoric acid sealed MgO-ZrO 2 coatings provide detailed information on the phases in the sealed coatings and the bonding mechanism of phosphate-based sealants on zirconia. In the case of aluminum phosphate sealed alumina and chromia, the primary objective is to add clarity on the bonding mechanism by means of transmission electron microscopy. Investigations of the sealing-layer interface indicate that the sealing of the layer lamellas is due to chemical reactions. Paper includes a German-language abstract.

This study analyzes the tribological behavior of nickel-graphite and aluminum-silicon-polyester thermal sprayed coatings and the effect of non-metallic compounds. Self-lubricating coating composites based on a metallic matrix with ceramic or polymeric filler phases show potential applications requiring high wear resistance and thermal stability at low cost. In some cases, the nickel-graphite layer may eliminate the need for external lubricants or lubricating systems. Paper includes a German-language abstract.

In this paper, the authors use computational tools to simulate thermal and mechanical processes involved in plasma spraying that lead to crack formation and delamination. The substrate-coating system is represented by a metal strip (120 x 20 x 2 mm) and a ceramic layer with a thickness of 0.06 mm. The transient heat transport problem and stress-deformation state of the 3D sample is solved via stress relaxation due to plastic deformation and distributed displacements or cracking. Paper includes a German-language abstract.

In this paper, spectroscopic and electrostatic probe measurements are made to examine the characteristics of a supersonic dc plasma jet near the surface of titanium plate during a nitriding treatment. The low-pressure nitriding process is done using a mixture of ammonia, nitrogen, and hydrogen gasses. Heating effects from the plasma are evaluated with nickel slug and thermocouple attached to the plate. The authors present the results of their study along with observations, insights, and suggestions on how to improve plasma nitriding processes. Paper includes a German-language abstract.

This paper presents the results of long-term thermal cycling tests on plasma-sprayed thermal barrier coatings, including coating samples produced with functionally graded materials. The role of oxidation is also considered based on the results of elemental analysis. The authors explain how the coatings were produced and tested and present and analyze the test results. The thermal barrier coatings formed with functionally graded materials were found to be relatively unaffected after the long-term thermal cycling test and showed no signs of oxidation. Paper includes a German-language abstract.

This study examines the influence of in-flight particle properties and substrate temperature on the quality of ceramic layers obtained at atmospheric plasma sprayings. Investigators sprayed aluminum oxide and zirconium dioxide powders on metal substrates, using infrared temperature measurement techniques to monitor the process. The authors present the test data and explain what it reveals about particle flattening behavior, coating morphology, and the effect of cooling. The investigations show that the influence of substrate temperature must not be overlooked if layer properties are to be predicted and controlled. Paper includes a German-language abstract.

This work investigates the processes involved in the formation of fragmented layers produced on the surface of ceramic coatings by means of laser melting. For the experiments, plasma sprayed zirconia was applied to steel substrates and treated with CO 2 and Nd:YAG lasers. The modified layers were found to consist of macro-fragments 500-2000 µm in size, which in turn consist of micro-fragments 20-70 µm in size. Crack gaps were observed at both levels with widths of 10-15 µm and 1-5 µm, respectively. Heat resistance, hardness, density, and roughness were determined before and after laser melting, and the changes measured are shown to depend on emitted laser power. Paper includes a German-language abstract.

In this paper, atmospheric plasma spraying is used to produce metal-insulator-metal structures that emit ultraviolet light via electrical discharge when sufficient voltage is applied. The metal layers are sprayed with molybdenum alloy powders and the insulator, a 50 to 100 μm dielectric layer, is sprayed with zirconia powder. The authors describe the fabrication process, assess the characteristics of the layers, and present test results that quantify the radiant power of the emitted UV light. Output power and efficiency of the plasma-sprayed structures are compared with that of commercial excimer lamps and the effects of coating erosion due to electrical discharge are discussed. Paper includes a German-language abstract.

This paper assesses the effect of laser remelting on nickel-base coatings produced by thermal spraying. NiAl, NiCr, and NiCrAlMoFe layers are deposited on steel substrates via flame and plasma spraying and treated with a CO 2 laser operated at different power levels. The treated layers are evaluated based on microstructure, hardness profile, and wear resistance. Plasma-sprayed NiCrAlMoFe layers treated at a power of 1000 W exhibited the highest wear resistance. Paper includes a German-language abstract.