Abstract
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.
Highlights
Functionalization of surfaces with chemisorbed molecules is an attractive route to tailor interfacial properties such as lubricity[1,2,3] and wetting.[2,3,4,5] Self‐assembled monolayers (SAMs) have been widely used in recent years to this end due to their durability and relative ease of preparation.[1]
In order to study the effectiveness of NaOH(aq) as a method of removing these chemisorbed species, we have evaluated this method against O2 plasma cleaning
The surface composition and morphology of the TiO2 coated Hot‐dip galvanized (HDG)‐steel substrate have been in detail previously.[24]
Summary
Functionalization of surfaces with chemisorbed molecules is an attractive route to tailor interfacial properties such as lubricity[1,2,3] and wetting.[2,3,4,5] Self‐assembled monolayers (SAMs) have been widely used in recent years to this end due to their durability and relative ease of preparation.[1]. Oils and oil‐based lubricants are widely used to reduce friction in these processes.[14,15] Thicknesses of these lubricant films are dictated by the surface roughness of the materials[3] that are undergoing plastic deformation, because it is necessary that the lubricant covers all of the surface features in order to prevent wear This leads to an over compensation of the amount of lubricant that is applied, which increases cost and waste because excess lubricant must be removed to prevent impacting on subsequent sheet metal forming operations (eg, painting, welding[16]). Detailed surface characterization (X‐ray photoelectron and infrared [IR] spectroscopy) allied to water contact angle (WCA) measurements to study surface wetting have been combined with scanning electron microscopy to study how NaOH(aq) treatment affects the galvanized steel surface These data have been correlated with the tribological properties of the functionalized and NaOH‐treated surfaces using linear friction testing (LFT) and confocal microscopy. It was used as comparison to study the efficacy of the NaOH(aq) treatment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
