Surface lubricity on TiO2‐coated galvanised steels can be controlled by solution depositing perfluorooctanoic (C8), lauric (C12) or stearic (C18) acids to avoid lubricating oils/emulsions or substrate pre‐etching to remove surface oxide that add cost and waste. Water contact angles reveal increased surface hydrophobicity on coated samples that correlate with linear friction testing, suggesting water contact angle can be used to screen lubricity compounds. Linear friction testing shows that C12 and C18 lower the coefficient of friction (μ) by 50–60% compared with uncoated substrates whilst C8 drops μ from 0.31 to 0.22. Surfaces have been characterised by X‐ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy, whilst infrared confirms that as‐deposited coatings contain physisorbed and deprotonated acids chemisorbed through esters and thermal gravimetric analysis confirms increasing loadings from C8 to C12 to C18. Surface washing removes physisorbed material and lowers μ by increasing surface organisation and alkyl chain packing that enhances frictional energy dissipation through steric quenching. Copyright © 2017 John Wiley & Sons, Ltd.

The tribological properties of octyl-, dodecyl-or octadecylphosphonic acid coatings on TiO 2coated galvanized steel substrates have been studied using linear friction testing (LFT) as potential lubricants for deep drawing automotive steels. LFT data show that the coatings reduce the coefficient of friction by > 65% from 0.31 to < 0.11. Confocal microscopy reveals that phosphonate-coated surfaces suffer considerably less wear than uncoated substrates during LFT. Water contact angle (WCA), XPS and IR data show that physisorbed phosphonates are removed by acetone washing leaving chemisorbed material. Data from a month-long ageing study using WCA, XPS and IR data shows that most of the physisorbed phosphonates become chemisorbed with time increasing hydrophobicity and tribological properties of the surfaces. Most of the changes occur within 14 days of coating and, after 21 days, no further surface changes were observed.

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Pyridine and some of its derivatives have been evaluated as inhibitors for the corrosion of API‐45 steel in NACE sour solution. Amongst the various methyl and halogen substituted pyridine compounds, 2,4,6‐trimethyl pyridine is found to afford maximum protection followed by 2,6‐dimethyl pyridine, >2,4‐dimethyl pyridine, >3‐bromopyridine, >2‐methyl pyridine, 4‐methyl pyridine, 3,5‐dimethyl pyridine, >2 and 3‐chloropyridine>pyridine. These results have been discussed in the light of availability of the electron densities with the nitrogen atom of the pyridine ring. The inhibitive periormance of all the inhibitors is found to deteriorate with increase in temperature from 30 to 60°C and with passage of time. The values of heat of absorption and free energy of absorption indicates that the inhibitors have a chemical type of absorption at the metal/electrolyte interface. Polarization diagrams and shift in open circuit potential in the presence of inhibitors indicate that these compounds retard the cathodic as well as anodic reaction process.

This paper studies the removal of chemisorbed carboxylates and phosphonates from TiO2‐coated galvanized steel using NaOH(aq). XPS and FTIR data show that NaOH(aq) is effective at desorbing these species and so is an alternative to gas phase processes (eg, plasma cleaning). Tribological investigations show that NaOH(aq)‐treated surfaces show reduced friction and wear, relative to the “as‐received” galvanized steel. This is ascribed to carbonate (present as an impurity in NaOH) that adsorbs to the surface of the substrate during NaOH(aq) immersion. Carbonate removal through sonication in water generates surfaces that show friction similar to “as‐received” galvanized steel. This work is useful in areas (eg, automotive manufacturing), where the effective removal of lubricants following tribological contact is key to subsequent paint adhesion.