The role of group IVB active metals in silver brazers on zirconium diboride wetting

The wetting behaviour of Ag-X (X = Ti, Zr, Hf) molten alloys in contact with sintered ZrB2 - substrate is described in terms of spreading kinetics and contact angles. The Ag-X / ZrB2 systems have been studied thermodynamically and experimentally. The measurements were performed by the sessile drop technique at T=1323 K and under controlled atmosphere. Different interfacial microstructures have been characterised by SEM and EDS analyses. The results show the determinant role of transition metals in understanding of physico-chemical factors that are responsible for bonding of ZrB2 ceramics.