Wettability for understanding the behaviour of new filler materials for sinter-brazing

ABSTRACT

The success of the sinter-brazing technique depends on the control of the liquid phase of the brazing alloy. Therefore, it is necessary to design the composition of the brazer taking into account its wettability, infiltration capacity, chemical reaction with the base material and development of the final microstructure. The present work pretends to analyse the wettability of a new proposal for sinter-brazing, in order to understand the behaviour of the liquid phase during sintering. For that purpose, the sessile drop technique is used for tracking the variation of the contact angle on different substrates and atmospheres. Fe and FeC are the chosen substrates and the experiments will be carried out under inert (Ar) and reducing (N₂–H₂) conditions. After the wetting test, SEM microscopy allows analysing the cross-section of the drop/substrate interface, so that important phenomena can be observed, such as dissolution of the solid, diffusion of alloying elements and formation of precipitates. Besides, DICTRA® software is used to simulate the kinetics of liquid/solid interaction and the possible dissolution processes. Furthermore, the wetting behaviour of the designed brazing alloy is compared with the wettability of commercial filler materials.

This paper is part of a special issue on the Advances in Materials and Processing Technologies (AMPT) 2015 and has subsequently been revised and extended before publication in Powder Metallurgy.

KEYWORDS:

• Wetting
• contact angle
• liquid phase
• sinter-brazing
• brazing alloy
• DICTRA®

Acknowledgements

This work has been developed under the international project Höganäs Chair and its support is gratefully acknowledged. The authors also wish to thank Dr A. Muñoz Castellanos from Physics Department at Universidad Carlos III de Madrid for his assistance in the ingots production. DIMMAT project (Programme S2013/MIT-2775) funded by Madrid region has supported the development, as well.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

M. Campos http://orcid.org/0000-0002-8360-9561