Sealers in use with Micro Arc Oxidation for rough service environments in the O&G industry

Sealers in use with MAO coatings for O&G industry

New exploitation methods in the O&G industry, creates a need of either high performance alloys or coatings for changing PH in ranges between 0-13 ,applications considered are Aluminum made core barrels, Drill pipes, and others.  

Micro Arc Oxidation (MAO) is an electrochemical process of oxidation applied to Aluminum or TSA Aluminum, to grow a dense, ductile ceramic oxide layer that improves, wear, thermal, and corrosion properties.

Due to its porous nature, a special sealing process is required.  sealing the pores and micro discontinuities on the ceramic layer created by the MAO process.

Excellent test results for large PH range using the following sealers after the MAO process: 1.       Organo Ceramic sealer cured at 120-200° C. 2.       Organic sealer applied by CVD.

Two groups of samples were tested: flat coupons, and cut tubes, due to geometry considerations.  

Partial Tests list:

•       10% EDTA +1% citric acid.

•       7.5%wt HCl +1.5%wt HF at 66°C for 140 hours per ASTM G 31-72 (2004) 

•       Brine  solution @ 93°C, 60 days per ASTM G 31-72 (2004).

•       Brine solution @ 100°C, pH 11.5, 30 days.