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Title: COATINGS FOR PROTECTION OF EQUIPMENT FOR BIOCHEMICAL PROCESSING OF GEOTHERMAL RESIDUES: PROGRESS REPORT FY 97

Thermal sprayed ethylene methacrylic acid (EMAA) and ethylene tetrafluoroethylene (ETFE), spray-and-bake ETFE and polyvinylidene fluoride (PVDF) and brushable ceramic-epoxy coatings were evaluated for corrosion protection in a biochemical process to treat geothermal residues. The findings are also relevant to other moderate temperature brine environments where corrosion is a problem. Coupon, Atlas cell, peel strength, cathodic disbondment and abrasion tests were performed in aggressive environments including geothermal sludge, hypersaline brine and sulfur-oxidizing bacteria (Thiobadus ferrooxidans) to determine suitability for protecting storage tanks and reaction vessels. It was found that all of the coatings were resistant to chemical attack and biodegradation at the test temperature of 55 C. The EMAA coatings protected 316L stainless steel from corrosion in coupon tests. However, corrosion of mild steel substrates thermal sprayed with EMAA and ETFE occurred in Atlas cell tests that simulated a lined reactor operating environment and this resulted in decreased adhesive strength. Peel tests to measure residual adhesion revealed that failure mode was dependent on exposure conditions. Long-term tests on the durability of ceramic-epoxy coatings in brine and bacteria are ongoing. Initial indications are that this coating has suitable characteristics. Abrasion tests showed that the ceramic-epoxy had good resistance to the abrasive effectsmore » of sludge. Thermal sprayed EMAA coatings also displayed abrasion resistance. Cathodic disbondment tests in brine at room temperature indicated that EMAA coatings are resistant to disbondment at applied potentials of {minus}780 to {minus}1,070 mV SCE for the test conditions and duration. Slight disbondment of one specimen occurred at a potential of {minus}1,500 mV SCE. The EMAA may be suited to use in conjunction with cathodic protection although further long-term, higher temperature testing would be needed.« less
Authors:
Publication Date:
OSTI Identifier:
757096
Report Number(s):
BNL--64991; EB4001
R&D Project: AS017EECD; EB4001; TRN: AH200034%%236
DOE Contract Number:
AC02-98CH10886
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1 Nov 1997
Research Org:
Brookhaven National Lab., Upton, NY (US)
Sponsoring Org:
USDOE Office of Energy Research (ER) (US)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 15 GEOTHERMAL ENERGY; PROTECTIVE COATINGS; POLYMERS; CORROSION PROTECTION; WASTE PROCESSING PLANTS; GEOTHERMAL FLUIDS; BRINES; MATERIALS TESTING; STORAGE FACILITIES; CHEMICAL REACTORS Geothermal Legacy