Abstract
The behavior of elements composing ruby and brazing filler metals at the brazing interface was examined by EPMA, and the construction of reaction layer formed at the brazing interface was examined by X-ray diffraction method, in order to investigate the corrosion phenomina of ruby by active metal brazing filler (Ag-Cu-Ti). The corrosion depth of ruby brazed under various conditions were evaluated by measuring surface roughness, in order to examine the relation between the corrosion depth of ruby and brazing condition.
The examination of brazing interface by EPMA showed that the reaction layer was constituted by two distinct layers with different titanium content. According to the X-ray diffraction method, the reaction layer formed adjacent to ruby was mainly constituted with TiO. Aluminum made from corroded ruby diffused outside of TiO-layer and formed the secondary reaction layer constituted by Ti3AI, Cu2Ti4O, AICu and CuxTiy. These experimental results showed that ruby was reduced by titanium contained brazing filler metal. According to the corrosion test using Ag-Cu-4 mass%Ti, the isothermal corrosion depth of ruby increased proportional to square root of brazing time in the temperature range of 1123 K to 1223 K. The temperature dependence of the rate constants fits an Arrhenius equation yielding activation energies of 224.2 kJ/mol.
