Chapter 43. Interface Reactions between Beta-Sialons and Cu/Cu₂O

Summary

Fully dense β-sialons with different z-values according to the formula Si_6-2Al₂O₂N_8-2 have been prepared, with and without addition of a sintering aid (Y₂O₃). The sialon ceramics were heat-treated in vacuum at 1000°C, embedded in Cu, Cu₂O, and in a Cu/Cu₂O mixture. The reaction zones formed have been studied by means of an SEM equipped with an EDS system and with use of X-ray powder diffraction technique. No reaction between pure Cu and the β-sialon could be observed, but the reaction between the Cu/C₂O mixture and the δ-sialons is severe. For sialons with low z-values, Cu₂O reacts with the sialons to form a glassy phase containing Si, Al, and Cu. Simultaneously, one part of the Cu₂O is reduced to Cu; meanwhile, the sialons are oxidized with the formation of N₂. With increasing z-value, less Cu and more CuAlO₂ is formed. Similar reaction products are formed when Cu₂O is used as matrix, but no Cu seems to be formed during the reaction with sialons of z = 3.8.