Properties Of Metallic Layers Sintered On Nitride Ceramics Depending On The Oxygen And Titanium Content In The Reactive Layer
Wiesława Olesińska Instytut Technologii Materiałów Elektronicznych, ul. Wólczyńska 133, 01-919, Warszawa
Annals 1 No. 1, 2001 pages 96-99
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abstract Production of metallic layers on non-oxide ceramic materials using the powder metallization method is difficult because of the poor wettability of these materials by both molten metals and by glasses. An additional difficulty is that, at temperatures above 11423 K, ceramic materials, both alumina nitride and silicon nitride ceramics are sensitive to humidity, since in an atmosphere of water-containing hydrogen ammonia is synthesized and nitrides decompose. The present study was, therefore, devoted to the deposition of metallic layers on nitride ceramic substrates, sintered in an atmosphere of dry hydrogen. The effects of the oxygen and titanium contents in the reactive layer deposited on nitride ceramics (AlN, Si3N4) on the wettability and sintering capability of the metallic layers were examined. The deposited metallic layers were standard Mo and Mn layers with the oxygen content ranging from 0 to 40 at. % and the titanium content from 0 to 8 at. %. The layers were sintered at a temperature between 1573 and 1653 K in a hydrogen atmosphere (dew point 203 K). The microstructure of the metallic layers was examined using a scanning electron microscope (figs 1-3) and an electron probe (fig. 4). A considerable migration of Al and Si to the interface layer was observed. The microstructure of the metallic layers sintered on nitride ceramics appeared to be very similar to the microstructure of metallic layers deposited on alumina oxide ceramics (figs 5-6). In the transition layers between the Al2O3 or AlN ceramic material and the metallic layer, a continuous glass layer is formed on the ceramic surface, which wets very well both the substrate and the metallic powders. The metallic layer is compact and the braze does not penetrate between the grains.