Research and Development Laboratory for Aerospace Materials in Rzeszow

Rzeszów, Poland

Research and Development Laboratory for Aerospace Materials in Rzeszow

Rzeszów, Poland
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Wierzba B.,AGH University of Science and Technology | Danielewski M.,AGH University of Science and Technology | Katarzyna Tkacz-Smiech,AGH University of Science and Technology | Sieniawski J.,Research and Development Laboratory for Aerospace Materials in Rzeszow
Chemical Vapor Deposition | Year: 2012

In this work we solve the problem of the simultaneous growth and competition of intermediate phases. The crystal lattice as the frame of reference for diffusion is defined, based on the volume continuity equation. It permits the computation of the material velocity in a system in which reactions at several moving interfaces occur. All reactions lead to the lattice shift due to the difference of diffusivities and molar volumes. We simulate the CVD process followed by annealing in a non-oxidizing atmosphere. The computed kinetics and concentration profiles are compared with experimental results. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Masset P.J.,TU Bergakademie Freiberg | Bogusz A.,TU Bergakademie Freiberg | Sieniawski J.,Research and Development Laboratory for Aerospace Materials in Rzeszow | Wierzba B.,AGH University of Science and Technology | Tkacz-Smiech K.,AGH University of Science and Technology
Defect and Diffusion Forum | Year: 2012

Results concerning nickel aluminisation with application of chemical vapour deposition method are presented. Two-step processing under investigation consists of Al chloride formation in the primary vessel and Al deposition in the secondary one. The initial gas stream is composed of HCl dissolved in H 2 at various ratios. It was shown that the choice of the [HCl]/[H 2] ratio and the determination of the optimum temperature to produce most preferential β-NiAl phase may be done with the use of thermodynamic calculations. The results obtained with application of FactSage program confirm essential influence of both initial [HCl]/[H 2] ratio (in the range between 0,05 and 100) and the temperature in the second vessel (1123 K - 1323 K) on aluminium chloride partial pressures and hence aluminium content in its gaseous donors and at the substrate surface (boundary condition for interdiffusion in Ni-Al system). It was confirmed that β-NiAl growth is favoured at low [HCl]/[H 2] ratios and high temperatures for which AlCl and AlCl 2 partial pressures increase with respect to that of AlCl 3. The thermodynamic predictions remain in agreement with CVD experiments. The presented thermodynamic data may be used as a source of essential information for designing further experiments in this field as well as for modelling of solid-state diffusion in Ni-Al system. © (2012) Trans Tech Publications.

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