Tris(dialkylamino)cyclopropenium dialkylphosphate ionic liquids as lubricants

Six new tris(dialkylamino)cyclopropenium dialkylphosphate ionic liquids (ILs), [C3(NR2)3]BEHP (NR2 = NEt2, NBuMe, NPr2, NBu2, NHex2, NDec2; BEHP = bis(2-ethylhexyl)phosphate), were prepared and characterised as potential lubricants. Thermophysical and thermochemical properties of these ILs were investigated, namely: viscosity, density, conductivity, miscibility, thermal stability and phase transitions. Miscibility studies indicated that [C3(NEt2)3]BEHP would not be suitable due to its water solubility and hexane immiscibility. [C3(NDec2)3]BEHP was not investigated as a lubricant due to its low purity (the chloride salt of this cation is also hexane miscible). Of the other four, [C3(NHex2)3]BEHP was found to exhibit significantly less wear for pin-on-disk test conditions than the standard phosphonium [P6,6,6,14]BEHP IL. The amount of wear was found to generally decrease with increasing molecular weight

Tris(dialkylamino)cyclopropenium dialkylphosphate ionic liquids as lubricants

Ionic liquids with cyclopropenium cations containing six large alkyl groups are found to provide excellent lubrication properties when combined with a large dialkylphosphate in steel-on-steel pin-on-disc testing

Development of waterborne anticorrosive coatings by the incorporation of coumarate based corrosion inhibitors and phosphate functionalization

Waterborne coatings are more industrially appealing for corrosion protection due to their low toxicity when compared to traditional solvent based coatings. In waterborne latex systems, the presence of surfactants is crucial, which can nevertheless contribute later to a poor performance of the final films in terms of barrier protection. This can be avoided by the use of polymerizable surfactants covalently bonded to the polymeric chains. In this work, particles of a latex loaded with an organic corrosion inhibitor, methoxy p-coumaric acid (H1), are further functionalized by the incorporation of a polymerizable surfactant, Sipomer® PAM-200 (SIP), by semibatch emulsion polymerization. The proposed system was hypothesized to ideally have higher barrier and corrosion protection properties due to the combination of H1 and SIP. However, the Electrochemical Impedance Spectroscopy results of the latexes cast on metal substrates indicate an antagonistic effect on the corrosion inhibition process rather than synergistic, as both species compete for the same moieties of the metallic surface. Thus, while the control coating with SIP (13.3 mg of SIP/g of polymer) showed impedances of 107.1–106.4 Ω and phase angles of 84–88 degrees over 24 h, the coating with H1 (3.3 mg of H1/g polymer) and SIP (13.3 mg of SIP/g of polymer) showed a less stable behavior with changes in impedances with time from 107.1 to 105.5 Ω and in phase angle from 86 to 72 degrees. The production of a bi-layer system avoids this antagonistic effect

A review of ionic liquid lubricants

Due to ever increasing demands on lubricants, such as increased service intervals, reduced volumes and reduced emissions, there is a need to develop new lubricants and improved wear additives. Ionic liquids (ILs) are room temperature molten salts that have recently been shown to offer many advantages in this area. The application of ILs as lubricants in a diverse range of systems has found that these materials can show remarkable protection against wear and significantly reduce friction in the neat state. Recently, some researchers have shown that a small family of ILs can also be incorporated into non-polar base oils, replacing traditional anti-wear additives, with excellent performance of the neat IL being maintained. ILs consist of large asymmetrical ions that may readily adsorb onto a metal surface and produce a thin, protective film under boundary lubrication conditions. Under extreme pressure conditions, certain IL compounds can also react to form a protective tribofilm, in particular when fluorine, phosphorus or boron atoms are present in the constituent ions

Film formation in trihexyl(tetradecyl)phosphonium diphenylphosphate ([P6,6,6,14][dpp]) ionic liquid on AA5083 aluminium alloy

Film formation in trihexyl(tetradecyl)phosphonium diphenylphosphate ([P6,6,6,14][dpp]) ionic liquid on AA5083 aluminium allo

Investigation on the tribological behavior and wear mechanism of parts processed by fused deposition additive manufacturing process

Fused deposition modeling (FDM) is a process for producing three dimensional products by layer by layer deposition directly from a digital file, becoming, more exciting among researchers from academia and industry in recent years. However, there is currently a lack of basic knowledge about the effect of multiple processing parameters on the wear behavior of FDM manufactured parts. The purpose of this study is to investigate the effect of different FDM fabrication parameters on the tribological behavior and wear mechanism of processed prototypes using definitive screening design and partial least squares regression. The FDM process parameters considered for experiments are layer thickness, air gap, raster angle, build orientation, road width and number of contours. The study of worn surfaces morphology was also conducted by scanning electron microscopy (SEM). In this study, the FDM process parameters are optimized using Nelder–Mead simplex method to minimize the wear rate and findings were validated by confirmation experiment. The results demonstrate that the FDM process parameters greatly affect the wear behavior of the manufactured parts due to the various microstructural modifications during manufacturing process that cause the changes in the wear properties, which is totally accordant to practical observation. The experimental results indicate that the wear rate of the FDM manufactured parts decreases with the decrease in layer thickness and build orientation, but with the increase in raster angle and air gap. It is found that the lowest and highest values for both road width and number of contours produce high wear rates compared to the wear rates at the center level of those parameters. This study provides useful guides for practical selection of FDM fabrication parameters to improve the tribological properties

Patterned copper sulfide thin films: a method for studying leaching behaviour

© CSIRO 2017.An experimental study on copper leaching from Cu1.85S thin films is presented, wherein copper extraction is quantitatively evaluated by changes in film thickness measured by white light interferometric profilometry. Changes in the film morphology and elemental composition, as assessed by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, are used to confirm that the loss in film thickness is due to changes in the copper content and that the resultant film species is consistent with the mechanism of copper dissolution. The Cu1.85S thin films were synthesized by chemical bath deposition. The leaching behaviour of copper from the films was investigated in acidic ferric sulfate media at pHs 1, 2, and 3, and pH 1 at redox potentials of ∼350-650mV versus Ag/AgCl in 3M KCl. The changes in the film thickness and copper sulfur ratio were shown to reflect copper dissolution behaviour from chalcocite. Leaching of the Cu1.85S films demonstrated a greater decrease in film thickness as pH decreased. In addition comparison of the order of reaction as a function of proton concentration in non-oxidative dissolution of Cu1.85S (0.06) and as a function of iron(iii) concentration in ferric oxidation of Cu1.85S (0.40) shows that the proton dissolution reaction is negligible. Leaching of the Cu1.85S films at redox potentials of up to ∼476.4mV versus Ag/AgCl in 3M KCl produced covellite and demonstrated greater decreases in film thickness with increases in the redox potential. Leaching of the films above ∼476.4mV resulted in the formation of spionkopite and demonstrated a much lesser decrease in film thickness. These results are consistent with Eh-pH diagrams for the Cu-S-H2O system

Imidazolinium inhibitor for mild steel in aggressive conditions

An organic salt comprising of an imidazolinium cation and a 4-hydroxy cinnamate anion has been shown to be a viable inhibitor for reducing the corrosion of steel in 0.01M NaCl aqueous solutions under acidic, neutral and basic conditions. The efficiency is particularly high at pH 8 (86%). Of most significance is that the individual components of this compound do not inhibit as effectively at equivalent concentrations, particularly at a pH of 2, suggesting there is a true synergy resulting from the combination of anion and cation. The immersion studies show the efficacy of these inhibitors to stifle corrosion as observed from optical, SEM and profilometry experiments. The mechanism of inhibition appears to be dominated by anodic behavior and further surface characterization work will investigate the origin of this inhibition and the synergy observed

Design of polymeric corrosion inhibitors based on ionic coumarate groups

Design of polymeric corrosion inhibitors based on ionic coumarate group

The effects of microstructure on the corrosion mechanism of steels used in ship structures

The effects of microstructure on the corrosion mechanism of steels used in ship structure