Methods and Apparatuses for Selecting Natural Product Corrosion Inhibitors for Application to Substrates

A method for selecting a replacement for a chromium-containing corrosion resistant compound to inhibit corrosion on aluminum or aluminum alloys, said method comprising:

• performing a diphenylpicrylhydrazyl radical scavenging assay on a candidate material;
• determining a diphenylpicrylhydrazyl radical scavenging assay corrosion inhibition value of said candidate material;
• performing steady state chronoamperometry testing on the candidate material, said steady state chronoamperometry testing comprising employing a copper rotating disk electrode;
• determining a corrosion inhibition efficiency percentage for said candidate material, said corrosion inhibition efficiency percentage based on the steady state chronoamperometry testing;
• correlating the diphenylpicrylhydrazyl radical scavenging assay corrosion inhibition value of the candidate material to the corrosion inhibition efficiency percentage of the candidate material;
• and
• selecting a candidate material from a plurality of candidate materials based upon a selected candidate material having both a diphenylpicrylhydrazyl radical scavenging assay corrosion inhibition value greater than about 80 and a corrosion inhibition efficiency percentage greater than about 80.

A method for predicting corrosion inhibition characteristics of a corrosion resistant candidate material in a corrosion resistant formulation, said method comprising:

• performing a plurality of corrosion inhibition testing protocols on a plurality of candidate materials, said plurality of corrosion inhibition testing protocols comprising:
• a diphenylpicrylhydrazyl radical scavenging assay;
• and
• a steady state chronoamperometry testing protocol, said steady state chronoamperometry testing employing a copper rotating disk electrode;
• determining a diphenylpicrylhydrazyl radical scavenging assay corrosion inhibition value of said plurality of candidate materials;
• determining a corrosion inhibition efficiency percentage for said plurality of candidate materials, said corrosion inhibition efficiency percentage based on the steady state chronoamperometry testing;
• correlating the diphenylpicrylhydrazyl radical scavenging assay corrosion inhibition value of at least one of plurality of candidate materials to the corrosion inhibition efficiency percentage of at least one of the candidate materials;
• selecting a candidate material from the plurality of candidate materials based upon a selected candidate material having both a diphenylpicrylhydrazyl radical scavenging assay corrosion inhibition value greater than about 80 and a corrosion inhibition efficiency percentage greater than about 80, said candidate material comprising an extract derived from a plant;
• and
• combining the selected candidate material with a polyurethane-containing formulation to form a polyurethane-containing anti-corrosion formulation.

A method for selecting a plant extract for use in a corrosion inhibiting coating for a substrate material comprising:

• obtaining a diphenylpicrylhydrazyl radical scavenging assay corrosion inhibition value of at least about 80 of a candidate material derived from a plant extract;
• obtaining a corrosion inhibition efficiency percentage of at least about 80 for said candidate material derived from a plant extract, said corrosion inhibition efficiency percentage obtained by performing steady state chronoamperometry testing on the candidate material, said steady state chronoamperometry testing employing a copper rotating disk electrode;
• correlating the diphenylpicrylhydrazyl radical scavenging assay corrosion inhibition value to the corrosion inhibition efficiency percentage to obtain a correlation of approximately 1:1 (+/−10%) between the diphenylpicrylhydrazyl radical scavenging assay corrosion inhibition value to the corrosion inhibition efficiency percentage;
• and
• combining the sample derived from a plant extract with a primer comprising a polyurethane to form a polyurethane-containing anti-corrosion formulation.