Nanoscale Boehmite Filler for Corrosion- and Wear-resistant Polyphenylenesulfide Coatings
We evaluated the usefulness of nanoscale boehmite crystals as a filler for anti-wear and anti-corrosion polyphenylenesulfide (PPS) coatings exposed to a very harsh, 300°C corrosive geothermal environment. The boehmite fillers dispersed uniformly into the PPS coating, conferring two advanced properties: First, they reduced markedly the rate of blasting wear; second, they increased the PPS's glass transition temperature and thermal decomposition temperature. The wear rate of PPS surfaces was reduced three-fold when 5 wt% boehmite was incorporated into the PPS. During exposure for 15 days at 300°C, the PPS underwent hydrothermal oxidation, leading to the substitution of sulfide linkages by sulfite linkages. However, such molecular alteration did not significantly diminish the ability of the coating to protect carbon steel against corrosion. In fact, PPS coating filled with boehmite of ≤ 5 wt% adequately mitigated its corrosion in brine at 300°C. One concern in using this filler was that it absorbs brine. Thus, adding an excess amount of boehmite was detrimental to achieving maximum protection.