Brazing of Si_3N_4 to Metals with Al Filler (Report I) : Si_3N_4/Si_3N_4 and Si_3N_4/Ti or Nb Joints(Materials, Metallurgy & Weldability)
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The wettability of molten aluminum on Si_3N_4 was investigated by a sessile drop technique in a vacuum. The joining of Si_3N_4 to Si_3N_4, and Si_3N_4 to Ti or Nb was performed using Al filler metal. The joining mechanism was investigated by transmission electron microscopy, scanning electron microscopy and EDX microanalysis. The work of adhesion of aluminum on Si_3N_4 increases significantly with increasing temperature, and aluminum definitly wets Si_3N_4. The joining strength of Si_3N_4/Si_3N_4 joint with Al filler exhibits the maximum of 210MPa at elevated temperature of 373K, and decreases with further increasing testing temperature. The strength of Si_3N_4/Ti or Nb joint with Al filler is about half the strength of Si_3N_4/Si_3N_4 joint. The stress arisen from the thermal difference between Si_3N_4 and metal provides the detrimental effect on the strength of the Si_3N_4/metal joint. At the joining layer of Si_3N_4/Ti or Nb joint the intermediate phase of TiAl_3 or NbAl_3 was formed.
- Transactions of JWRI
Transactions of JWRI 18(1), 81-86, 1989-06