An in-depth study was undertaken to correlate chromate conversion coating process variables to coating weights obtained on aluminum braze sheet coupons. The purpose of this study was (1) to determine the target coating weight (mg/sq. ft.) that was required for adequate corrosion protection; (2) to correlate conversion coating process variables to coating weights on aluminum braze sheet coupons; and (3) to find the optimum process conditions that will achieve target coating weight.
Rigorous statistical analysis was conducted to correlate the process parameters to coating weight. Polarization tests were conducted whereby open circuit potential and pitting potential were compared to determine the minimum coating weight needed to achieve corrosion protection.