Investigation of Plating Process Variability and Mechanism for Oxide Disruption in a Ni-Modified Fluxless Brazing Process for Aluminum Alloys

Abstract

The effect of surface oxides and the presence of ternary constituents were examined using differential scanning calorimetry (DSC) along with SEM, EDX, and TEM studies to quantitatively analyze the role of nickel in its use as a fluxless braze promoter for aluminum alloys during brazing. This braze promoter exhibits an exothermic reaction due to intermetallic reaction with neighboring aluminum and silicon which disrupts the tenacious surface oxide allowing molten liquid to flow. Seven surface conditions were created with various oxide thicknesses and surface chemistries to better understand their role in this fluxless brazing process. These surface altered coupons were then sputtered with various nickel thicknesses. DSC and post characterization techniques confirmed that a larger surface oxide poses a barrier to this intermetallic reaction and that nickel still remained present on the surface.