Evaluation of Strategies To Reduce Tribocorrosion of Steel Components
Date
2020-04-30
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Abstract
In oil and gas applications, such as for rod pumps used in oil extraction, metallic components are often subjected to corrosive environments and simultaneously abraded by sand. This presents a serious problem as wear reduces efficiency and necessitates the replacement of parts, resulting in increased costs. The purpose of this thesis is to examine strategies for reducing tribocorrosion, including boronizing treatment processes for steels, and using friction reducers and chemical additives in pipelines carrying fracking fluid. The tribological behaviour of uncoated samples, coated samples, and pipe segments were examined in sliding under both dry and corrosive conditions. 0.5M NaCl solution and fracking fluid referred to as high Total Dissolved Solids (TDS) water was used in conjunction with a potentiostat to artificially induce electrocorrosion. Friction coefficients were determined through the use of a home-built linear reciprocating tribometer, and wear coefficients were calculated using an optical profilometer and hardness testing. Additionally, Energy Dispersive X-ray Spectroscopy (EDS) was employed to perform chemical characterisation of tribofilms and corrosion by-products. From the experiments, it was discovered that sample boron-doped boronized steels yielded the lowest friction coefficient (μ = 0.189±0.003) and lowest pseudo-wear coefficient (k = [5.38±0.17]*10^-8 MPa^-1) in dry sliding. This same coating also showed reduced friction with enhanced corrosion in 0.5M NaCl as opposed to AISI 1018 steel which had worse friction performance under corrosion. From the EDS studies, a mechanism was hypothesized for the cause of friction reduction for corroding boronized steels; sliding leads to the wearing of a thin oxide film produced during corrosion which then acts as a lubricant or an antiwelding surface. From tests performed on steel pipe segments, it found that DynaRate 6524 was the most effective friction reducer in high TDS water, decreasing friction by 20% while DWP 621 on the contrary hindered friction performance resulting in a 20% increase in friction. DyanRate 6524 did not affect wear rates significantly whereas DWP 621 increased wear. It was also observed that electrically-induced corrosion poorly affected the friction performance of DynaRate 6524 friction reducer, however, CalGuard 3100 oxygen scavenger which is meant to inhibit corrosion had no affect on the friction performance of DynaRate 6524.
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Keywords
Tribology, Tribocorrosion, Friction, Wear, Corrosion
Citation
Wong, B. C. (2020). Evaluation of Strategies To Reduce Tribocorrosion of Steel Components (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.