Fluorocarbon Lubricant Research Articles

Fluorocarbon lubricant impregnated nanoporous oxide for omnicorrosion-resistant stainless steel

Corrosion protection coatings have been required for long-term uses of metallic materials applied in various environments incorporating liquid and/or vapor phase corrosion reactants. In this study, we introduce a fluorocarbon lubricant impregnated nanoporous oxide (FLINO) coating on stainless steel for realizing effective resistances against corrosive media in both liquid and vapor phases. The FLINO layer on stainless steel significantly enhances corrosion resistances with superior durability and self-healing capability. The combination of nanoporous structure and fluorocarbon lubricant layer provides an outstanding atmospheric corrosion resistance, which has been a serious issue to be overcome on corrosion-resistant coatings. Therefore, the FLINO coating exhibiting stable and remarkable corrosion resistance against both liquid and vaporized corrosive media, called omnicorrosion-resistance, gives a new route for the versatile protection of metallic materials in various environments encompassing both underwater and atmospheric applications.

Fouling-resistant behavior of liquid-infused porous slippery surfaces

Marine economy is seriously affected by marine biofouling, which has plagued people for thousands of years. Although various strategies have been developed to protect artificial surfaces against marine biofouling, cost-effective biofouling-resistant coating is still a goal in pursue. Herein, a cost-effective liquid-infused porous slippery surface (LIPSS) was facilely prepared by using poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) elastomer to form microsphere surfaces, followed by infusing fluorocarbon lubricants into the porous structure. The as-prepared slippery surfaces were characterized by static water contact angle, sliding velocity and sliding angle analysis. We also investigated the adhesion behavior of Escherichia coli (E. coli) and limnetic algae on different surfaces. It is confirmed that the slippery surfaces have better anti-biofouling properties than the porous SEBS reference. This cost-effective approach is feasible and easily produced, and may potentially be used as fouling-resistant surfaces.

Self-cleaning and antibiofouling enamel surface by slippery liquid-infused technique.

We aimed to create a slippery liquid-infused enamel surface with antibiofouling property to prevent dental biofilm/plaque formation. First, a micro/nanoporous enamel surface was obtained by 37% phosphoric acid etching. The surface was then functionalized by hydrophobic low-surface energy heptadecafluoro-1,1,2,2-tetra- hydrodecyltrichlorosilane. Subsequent infusion of fluorocarbon lubricants (Fluorinert FC-70) into the polyfluoroalkyl-silanized rough surface resulted in an enamel surface with slippery liquid-infused porous surface (SLIPS). The results of water contact angle measurement, diffuse-reflectance Fourier transform infrared spectroscopy, and atomic force microscope confirmed that the SLIPS was successfully constructed on the enamel surface. The antibiofouling property of the SLIPS was evaluated by the adsorption of salivary protein of mucin and Streptococcus mutans in vitro, as well as dental biofilm formation using a rabbit model in vivo. The results showed that the SLIPS on the enamel surface significantly inhibited mucin adhesion and S. mutans biofilm formation in vitro, and inhibited dental plaque formation in vivo.

Total reflection X-ray photoelectron spectroscopy as a semiconductor lubricant elemental analysis method

Photoelectron spectra from a typical hard disk storage media device (HDD) were measured at total reflection and non-total reflection at unburnished, acetone-cleaned, and argon-sputtered conditions. F, O, N, and C usually making the upper layer of a typical hard disk medium were detected. Enhancement of the photoelectron emission of the fluorocarbon lubricant was observed at total reflection. Pt and Co were only found by non-total X-ray photoelectron spectroscopy (XPS) because they are constituents of a deeper region than the top and interface regions. Argon-sputtered, ultrasonic acetone-cleaned, and unburnished top layers were compared at total and non-total reflection conditions. Total reflection X-ray photoelectron spectroscopy (TRXPS) is demonstrated to be a powerful tool for storage media lubrication layer chemical state analysis, reliable for industrial quality control application , and reproducible.

Slippery Liquid-Infused Porous Surfaces Showing Marine Antibiofouling Properties

Marine biofouling is a longstanding problem because of the constant challenges placed by various fouling species and increasingly restricted environmental regulations for antifouling coatings. Novel nonbiocidal strategies to control biofouling will necessitate a multifunctional approach to coating design. Here we show that slippery liquid-infused porous surfaces (SLIPSs) provide another possible strategy to obtaining promising antifouling coatings. Microporous butyl methacrylate-ethylene dimethacrylate (BMA-EDMA) surfaces are prepared via UV-initiated free-radical polymerization. Subsequent infusion of fluorocarbon lubricants (Krytox103, Krytox100, and Fluorinert FC-70) into the porous microtexture results in liquid-repellent slippery surfaces. To study the interaction with marine fouling organisms, settlement of zoospores of the alga Ulva linza and cypris larvae of the barnacle Balanus amphitrite is tested in laboratory assays. BMA-EDMA surfaces infused with Krytox103 and Krytox100 exhibit remarkable inhibition of settlement (attachment) of both spores and cyprids to a level comparable to that of a poly(ethylene glycol) (PEG)-terminated self-assembled monolayer. In addition, the adhesion strength of sporelings (young plants) of U. linza is reduced for BMA-EDMA surfaces infused with Krytox103 and Krytox100 compared to pristine (noninfused) BMA-EDMA and BMA-EDMA infused with Fluorinert FC-70. Immersion tests suggest a correlation between the stability of slippery coatings in artificial seawater and fouling resistance efficacy. The results indicate great potential for the application of this concept in fouling-resistant marine coatings.

Adsorption of Fluorinated Ethers and Alcohols on Fresh and Oxidized Carbon Overcoats for Magnetic Data Storage

Temperature programmed desorption has been used to study the desorption kinetics and desorption energies of perfluorodiethylether, (CF3CF2)2O, and 2,2,2-trifluoroethanol, CF3CH2OH, adsorbed on fresh and oxidized hydrogenated amorphous carbon (a-CHx) films. (CF3CF2)2O and CF3CH2OH serve as models for the ether backbone and hydroxyl end-groups of Fomblin Zdol, the lubricant most commonly used to lubricate the surfaces of amorphous carbon overcoats on magnetic data storage hard disks. Our measurements clearly reveal, for the first time, the effects of surface oxidation on the adsorption of fluorocarbon lubricants such as Fomblin Zdol on a-CHx films. Oxidation of the a-CHx surface increases the desorption energy of CF3CH2OH but has no observable impact on the desorption energy of (CF3CF2)2O. These results support the suggestion that the alcohols interact with the surface via hydrogen bonding. From a practical perspective, these results imply that the oxidation of the fresh a-CHx film may serve as a means to control or tailor the a-CHx surface to optimize the properties of the lubricant-overcoat interface in hard disks.

Comparative analysis of razor blade coatings using Auger electron spectroscopy

Razor blade technology involves not only the forming of the cutting edge (final facet) but the protection of that edge from damage and corrosion. This requirement has led to the deposition of various types of metallic, ceramic and organic coatings to the final facet to prolong the useful life of the blade. In this study, Auger electron spectroscopy and secondary electron microscopy are employed to characterize the final facet of razor blades from various manufacturers. Each analysis emphasized the final facet morphology and coating composition. The blades are analyzed before and after ‘pithing’ to remove the fluorocarbon lubricant and other oils found on most blades. The typical coating was found to be chromium, but platinum alloys and iron oxides are also observed. The chromium coatings are fully oxidized in some cases, and in others exhibit only a surface oxide. Sputter depth profiling is implemented to determine relative coating thickness and interfacial chemistry.

X-ray photoelectron spectroscopy investigation of fluorocarbon lubricant films

Fluorocarbon lubricants are of great interest in many applications where they are used in very thin layers. Control of the lubricant presence is easily performed by a surface analysis technique such as x-ray photoelectron spectroscopy. However, the interpretation of the spectra is not straightforward. A simple electronegativity description of the charge shifts is developed from the group electronegativity and the Sanderson equalization approaches. It is applied to two types of high molecular weight molecules, and allows us to assign the experimental photoelectron spectra of the two fluorocarbon lubricants under study.

Evaluation of the electron attenuation length for the determination of the lubricant overlayer thickness on magnetic disks with x-ray photoelectron spectroscopy

The electron attenuation length (AL) of the C 1s photoelectrons in a fluorocarbon lubricant overlayer λfc on sputter-carbon coated magnetic disks has been experimentally determined. The C 1s intensity ratio of the carbon substrate signal with overlayer thickness to the –CF2– signal gives a value of λfc, 2.88±0.68 nm. The result is discussed in a light of the problem associated with an accurate determination of the lubricant overlayer thickness with x-ray photoelectron spectroscopy.

Surface contamination on sputter carbon coated disks measured by using low energy photoelectron spectroscopy in an ambient atmosphere

The influence of surface contamination on sputtered carbon films on a rigid thin-film disk was evaluated with LEPS (low-energy photoelectron spectroscopy) and XPS (X-ray photoelectron spectroscopy). LEPS was as sensitive as XPS for detecting the surface contaminant. LEPS had the advantage of operating in an ambient atmosphere, while XPS was useful for the identification of the chemical species of the contaminant. The XPS analysis revealed that the main contaminant was due to water in air. XPS showed that the wettability of the fluorocarbon lubricant decreased with an increase in the exposure time of the sputtered carbon film to air before lubrication or with a surface-contaminant increase on the sputtered carbon film. >

Variable angle XPS investigation of lubricant films coated on sputtered carbon

AbstractThe thickness t of the fluorocarbon lubricant applied on the sputter‐deposited carbon substrates is measured using the uniform overlayer model where γc is the mean free path of the C 1s photoelectrons in the lubricant, R is the experimentally measured intensity ratio of the fluorocarbon to the hydrocarbon components of the C 1s line, θ is the photoelectron take‐off angle, and a is the ratio of C 1s intensity from the lubricant‐free substrate to that from the bulk lubricant. A procedure for experimentally determining the a value, using a partially gold‐coated graphite substrate as a reference, is reported. Values of 4.1, 2.9 and 2.2 were obtained for a respectively on sputter cleaned substrates of graphite, carbon on silicon wafer and carbon on thin film magnetic recording disk. The lower a values of the deposited films are attributed to the presence of voids in the films. Oxidation causes a decrease in a by reducing the carbon content of the substrates, The experimentally determined a values are verifled by monitoring the relative variation in the C 1s and the F 1s signal intensities as a function of θ. The angle dependence of a is discussed.

The Analysis of Lubricants on Magnetic Disks by Fourier Transform Infrared Spectroscopy

The analysis of fluorocarbon lubricant on magnetic storage disks by Fourier transform Infrared external reflectance spectroscopy is presented. Optimization of parameters for the analysis is discussed and methods of quantitative analysis are proposed. Results from a dedicated accessory for the task are shown.

FTIR determination of fluorocarbon lubricant film thickness on magnetic disk media

Fluorocarbon lubricants have been used extensively for Winchester-type media to minimize head disk interfacial wear and friction. The film thickness of these lubricants must be carefully controlled. This paper describes a non-destructive and cost-effective technique of measuring the average, relative thickness of lubricating films on rigid magnetic disks by using FTIR spectroscopy. Lubricant film thickness data obtained by FTIR correlated very well with those obtained by ESCA spectroscopy. The effect of surface roughness on lubricant retention during the lubrication process is also demonstrated.

ESCA determination of fluorocarbon lubricant film thickness on magnetic disk media

Fluorocarbon films are in extensive use as lubricants for Winchester-type disks, to reduce disk head wear and to reduce friction during landing and start-up. This paper describes a particularly precise and simple method of measuring the average, relative thickness of such films using ESCA spectroscopy. Film thicknesses are measured with a typical precision of 5% of value (lσ), over the operational range of these films.