ALUMINUM ALLOY ALUMINA-BASED CERAMIC INTERACTIONS/

Wetting experiments were performed on eutectic ZrO2/Al2O3 (ZA), ZrO2/A l2O3/TiO2 (ZAT), and ZrO2/Al2O3/SiO2 (ZAS) ceramic substrates with dif ferent Al alloys. Four major variables were tested to study the wettin g behavior of the different ceramic-metal systems. Variables include h olding time, melt temperature, alloy, and ceramic compositions. An exp erimental setup was designed to measure in situ contact angles using t he sessile drop method. For any ceramic substrate, a temperature over 950 degrees C was necessary to observe an equilibrium wetting angle of less than 90 degrees with pure Al; by alloying the aluminum, wetting could be observed at lower temperatures (theta = 76-86 degrees at 900 degrees C for Al-10 wt.% Si, theta similar to 72 degrees at 850 degree s C for Al-2.4 wt.% Mg) forming clean interfaces. Finally, ZAS specime ns reacted with molten Al alloys over 900 degrees C to produce Zr-Al b ased intermetallics at the metal-ceramic interface.