The influence of grain boundaries on the properties of refractory coatings produced with the aid of plasma arc deposition

Informazioni relative al progetto

ID dell’accordo di sovvenzione: INTAS-93-1451

Progetto chiuso

Data di avvio 1 Aprile 1995

Data di completamento 31 Marzo 1996

Finanziato da

• International Association for the promotion of cooperation with scientists from the independent states of the former Soviet Union (INTAS), 1993-

Costo totale

Nessun dato

Contributo UE

€ 50 000,00

Coordinato da

Universität Stuttgart
Germany

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Risultati sfruttabili

The influence of grain boundaries on the properties of refractory coatings produced with aid of plasma arc deposition

The development of processes for manufacturing tungsten (W) and molybdenum (Mo) coatings and foils with thickness of a few micrometres is technologically very important for the substitution of expensive massive parts made of W- or Mo-based alloys by parts in which a cheap matrix with a low melting temperature is coated with a few micrometres thick refractory layer or by refractory foils. The plasma arc deposition of W and Mo layers on different substrates (metals, ceramics and polymers) ensures higher sputtering rates for refractory materials in comparison with magnetron sputtering. Removing the substrate mechanically or chemically will be studied since this seems to be the only way to produce thin foils of Mo or W. In order to ensure a low degradation rate of the W and Mo coatings at elevated temperatures, the penetration of the substrate material with the lower melting point along grain boundaries (GBs) and the diffusion-induced recrystallization of the coatings must be prevented. For a description and prediction of GB-controlled properties of coatings the method of GB phase diagrams will be used. The penetration of Ni, Fe or Cu along GBs in W and Mo polycrystalline coatings and in W and Mo bicrystals will be investigated using electron-probe microanalysis, metallography, and, for the first time, low-energy ion scattering. The diffusion-induced recrystallization in W- and Mo-based coatings will be investigated by scanning and transmission electron microscopy. The misorientation spectra of grain boundaries in the coatings will be studied by the channelling pattern and Kikuchi line analysis. This research project will place existing successful bilateral partnerships onto a multilateral basis using the unique experience of Russian and Western Europe partners in different fields of coating technologies, GB properties and phase transitions.