Reducing Friction and Wear of a Zinc Substrate by Combining a Stearic Acid Overcoat with a Nanostructured Zinc Oxide Underlying Film: Perspectives to Super-Hydrophobicity

Abstract

In this study, a simple two-step process was developed to render zinc (Zn) surfaces super-hydrophobic for the purpose of lowering friction and increasing wear resistance. Zn substrates were immersed in an aqueous solution of N,N-dimethylformamide (4%, volume fraction v/v) to fabricate a ZnO film consisting of uniform and wellpacked nanorods. A self-assembled monolayer of stearic acid was then prepared on the ZnO-nanorod film to acquire super-hydrophobicity. Scanning electron microscopy, Fourier transform infrared microscopy, and water contactangle measurements were employed to analyze the morphological features, the chemical composition, and superhydrophobicity of freshly prepared samples. Moreover, the friction and wear behavior of the organic-inorganic composite film sliding against steel was evaluated in a ball-onplate configuration using a UMT-3 friction and wear tester. It was found that the stearic acid overcoat on the nanostructured ZnO film led to a large water contact angle of *155°as well as to significantly decreased friction and greatly extended wear resistance.

Corrosion protection of brasses and zinc in simulated urban rain

“…Instead of using inhibitors, the surface of metals can be made hydrophobic and thus protected against corrosion by being less wetted by liquid . Self‐assembled layers of carboxylic acids that adsorb by their carboxyl groups to positively charged metal surfaces, have been investigated on surfaces of many metals including Cu , brass , Al , Mg and Zn . We have investigated carboxylic acids, differing in length of the carbon chain, as corrosion inhibitors for Cu, Zn and brasses (Cu40Zn and Cu10Zn) in simulated urban rain .…”

Stearic Acid/Layered Double Hydroxides Composite Thin Films Deposited by Combined Laser Techniques

“…Both -CH 3 and -CH 2 - are hydrophobic groups and have low surface energy decreasing the surface energy of the surface they cover or of the materials they are grafted to [ 35 , 36 ]. The free -COOH band of solid stearic acid is still present in the spectrum of the as-deposited StMAPLE(266 nm) film while it vanishes in the spectrum of the film after 36 months of storage, which shows that the stearic acid had reacted with the Si surface, although there are no changes in contact angle value [ 37 , 38 ]. It has been observed that an “ordered” film of alkanoic acids is characterized by alkyl chains in all-trans configurations arranged in such a way that they are tilted from the normal surface at the same angle.…”

“…It has been observed that an “ordered” film of alkanoic acids is characterized by alkyl chains in all-trans configurations arranged in such a way that they are tilted from the normal surface at the same angle. This results in νCH 2 -asymmetric ≤ 2916 cm −1 [ 37 , 38 ]. Table 3 includes a column with the position of this peak.…”

Corrosion protection of brasses and zinc in simulated urban rain. Part II. The combination of inhibitors benzotriazole and 2‐mercaptobenzimidazole with stearic acid

“…The formation and properties of BTAH‐ and 2‐MBI‐layers on copper were investigated in our previous studies . Carboxylic acids also show good protection by forming hydrophobic layers of metal carboxylates on various metals . In our earlier work we investigated hydrophobic and corrosion protection properties of layers formed with carboxylic acids differing in carbon chain length.…”