Enhancement of an unused protective coating

A method for enhancing an existing substantially unused high temperature environmentally resistant metallic diffused aluminide protective coating on an article surface, the existing coating being within a first selected coating range, comprising the steps of:

• specifying a second selected coating range for the unused diffused aluminide protective coating, the second selected coating range being different from the first selected coating range in at least one of chemistry and physical condition;
• evaluating the existing unused metallic diffused aluminide protective coating to identify at least one substantially unused coating region that deviates from the second selected coating range by being deficient in at least one of chemistry and physical condition and the amount of being deficient;
• and then,
• without removing the existing unused metallic diffused aluminide protective coating, enhancing at least the coating region of the substantially unused diffused aluminide protective coating to the second selected coating range by steps including:
• a) applying over the unused metallic diffused aluminide protective coating at least to the unused coating region at least one secondary element selected from the group consisting of Pt, Rh, Pd, Cr, Si, Hf, Zr, and Y;
• and,
• b) heating at least the coating region to a temperature and for a time sufficient to diffuse the secondary element into the diffused aluminide protective coating to provide a treated coating region.