EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The aim of this work is to study the brazing of zirconia to titanium with pure gold. Brazing experiments were carried out under high vacuum (10-4 Pa) at different temperatures.
In order to determine the mechanisms of interfacial interactions at ZrO2/Au interface, wetting of zirconia by AuTi alloys was also studied. The spreading kinetics of the wetting process has been determined by sessile drop method using image capture system with a CCD camera.
The spreading kinetics and the final contact angle strongly depend on the experimental temperatures and especially on the active element content of the alloys. The contact angle decreases when the Ti content in the alloys increases.
The microstructures of the joint and of reactive interfaces were characterized by SEM, EDX and TEM, and compared with those obtained by the sessile drop technique.
From the SEM and TEM analyses, a TiOx reaction layer is highlighted at the ZrO2/Au interface. Its thickness and its chemical composition depend on the titanium content in the alloy. The relationship between the chemical composition of this layer and the wetting behavior is presented and discussed.
Four AuxTiy intermetallic compounds are observed at the Ti/Au interface. Some specific experiments were also performed in order to understand the formation and growth of these intermetallic compounds by solid-state interaction during heating up to the melting temperature as well as during isothermal holdings at brazing temperature.
Mechanical tests have been carried out in order to evaluate the mechanical strength of the joints. Moreover, SEM characterization of the samples after mechanical tests allowed to observe the fracture surfaces.