Wettability of aluminium nitride based ceramics of different porosity by two active silver based brazing alloys

Wettability of dense and porous AlN ceramics in contact with commercial active brazes CB4, CB5 of Ag-Cu-Ti compositions has been investigated. Contact angles have been measured during isothermal exposure at 810, 900 and 950degreesC in a vacuum of 1 x 10(-3) Pa. Results showed good wettability for dense samples. Contact angles for porous samples were higher by about 20-30degrees. Contact interaction has been studied for both forms of the ceramic. A layer of non-stoichiometric TiN has been identified in the interaction zone between dense AlN and CB4 or CB5. Formation of the interaction zone for porous AlN is accompanied by a process of melt penetration into pores and overlaps with an impregnation zone. (C) 2004 Elsevier B.V. All rights reserved.