Enhancement of the Water-Lubricated Tribological Properties of Hybrid PTFE/Nomex Fabric Laminate Composite via Epoxy Resin and Graphite Filler

This paper studied a hybrid polytetrafluoroethylene (PTFE)/Nomex fabric composite with lower friction coefficient (COF) and high underwater wear resistance. A pin-on-disk tribometer was used to test tribological properties under different applied loads and rotation speeds. The wear surface, transfer film and cross-section were analyzed by scanning electron microscope (SEM) and optical microscope. The results showed enhanced underwater tribological properties because of excellent self-lubricating properties of PTFE fibers and a good lubricating effect and load-carrying capacity of graphite fillers. Improved underwater mechanical strength was connected to the high strength of epoxy resin and high bonding force between Nomex and epoxy resin.

Ionic Liquids Based on Chromotropic Acid: Excellent Lubricating Additives for Aqueous System

In this paper, four ionic liquids based on chromotropate (CAILs) were prepared and applied to heighten the tribological performance of aqueous system on different metal friction contacts. Taking for the potential choice for water-based lubricating additive, CAILs exhibited excellent water solubility and corrosion resistance. Tribological results showed that the CAILs, especially the phenolic hydroxyl group decorated samples (TsnN4444 and TsnP4444), demonstrated extremely effective lubricating properties with the efficient friction and wear descent (69% and 83% for Fe, 47% and 94% for Cu, 74% and 69% for Al, respectively). Especially, the excellent load-carrying capacity was also presented with the highest PB (833N) and PD (1568N) values for TsnP4444. It is speculated that the CAIL molecular adsorption on the interface and further generation of tribochemical films are beneficial for their lubricating effects. resulting from the systematic discussion and analysis of CA, QCM, SEM, XPS, and FIB-TEM tests. However, TsN4444 and TsP4444 showed less effective lubricating performances and poor load-carrying capacities due to tribocorrosion of hydroxyl groups at the interface.

Improving Tableting Performance of Lactose Monohydrate by Fluid-Bed Melt Granulation Co-Processing

Co-processing is commonly used approach to improve functional characteristics of pharmaceutical excipients to become suitable for tablet production by direct compression. This study aimed to improve tableting characteristics of lactose monohydrate (LMH) by co-processing by fluid-bed melt granulation with addition of hydrophilic (PEG 4000 and poloxamer 188) and lipophilic (glyceryl palmitostearate) meltable binders. In addition to binding purpose, hydrophilic and lipophilic excipients were added to achieve self-lubricating properties of mixture. Co-processed mixtures exhibit superior flow properties compared to pure LMH and comparable or better flowability relative to commercial excipient Ludipress®. Compaction of mixtures co-processed with 20% PEG 4000 and 20% poloxamer 188 resulted in tablets with acceptable tensile strength (>2 MPa) and good lubricating properties (ejection and detachment stress values below 5 MPa) in a wide range of compression pressures. While the best lubricating properties were observed when glyceryl palmitostearate was used as meltable binder, obtained tablets failed to fulfil required mechanical characteristics. Although addition of meltable binder improves interparticle bonding, disintegration time was not prolonged compared to commercial excipient Ludipress®. Co-processed mixtures containing 20% of either PEG 4000 or poloxamer 188 showed superior tabletability and lubricant properties relative to LMH and Ludipress® and can be good candidates for tablet production by direct compression.

Defining-Measuring-Analysing-Improving-Controlling (DMAIC): Process and Improve Stability in Carbon Steel Industry

Phosphating is most common method for surface treatment and finishing of ferrous and nonferrous metal. It has excellent corrosion resistance, wear resistance, adhesion and lubricating properties besides its economic values and speed of application. Steel is one of the cheapest materials used in various industries and it requires corrosion resistance therapy. This study aims to provide possible solution to the rusty issue on carbon steel product by improving coating stability using Defining–Measuring–Analysing–Improving–Controlling (DMAIC) method. The result proposed that zinc phosphate coating material has to replace current iron phosphate coating due to the former is more corrosion time resistant than that of the latter.

THE INFLUENCE OF SYNTHETIC HYDROCARBON ON LUBRICATING PROPERTIES OF FUELS FOR TURBINE ENGINES

Recently, steps have been taken to introduce synthetic hydrocarbons to aviation fuels as biocomponents. This action is an innovative change in the approach to aviation fuels. This new approach to the assessment of fuel properties requires a revision of the existing criteria for their quality assessment, including those relating to tribological properties. In the requirements for Jet fuel, only the BOCLE test simulating continuous circular motion was used to assess lubricity. Research on the use of fuels containing components with highly differentiated chemical compositions indicate that the BOCLE test may be an insufficient criterion for assessing the lubricity of fuels for aircraft turbine engines. An additional HFRR test modelling the processes accompanying the reciprocating friction that occurs in some lubricated elements of the fuel system has been proposed. This article presents the results of BOCLE and HFRR tests on a range of Jet A1 fuel mixtures and various synthetic paraffin hydrocarbons. A preliminary analysis of the observed effect of synthetic hydrocarbons on the results of both tests is presented.

Сhanging the lubricity of diesel fuel with vegetable oil additive

Intriduction. The environmental safety of cars with a diesel engine does not lose its relevance. In the conditions of stricter requirements for diesel fuel, the content of many substances harmful to the environment, including sulfur, is not allowed. As is known, low-sulfur fuels require the presence of additives that improve the lubricating properties of diesel fuel. Non-compliance with the requirements for lubricity significantly affects the resource of the fuel supply system of a diesel engine, primarily the Common Rail system. In order with the circumstances listed above, we hypothesized that vegetable oil can serve in small concentrations to improve the lubricating properties of fuels.Materials and methods. In our research, we conducted experiments using the standard HFRR method (highfrequency translational motion of a ball rubbing against a plate in fuel). A microscope was used to visually assess the wear spots and measure their size. Diesel fuel was taken as samples for experiments and vegetable oil was added to it as an additive in certain proportions.Discussion and conclusions. The vegetable oil additive can improve the lubricity of diesel fuel, even if it does not comply with GOST for this parameter. The experiments conducted allow us to conclude that the vegetable oil additive as a percentage of diesel fuel almost linearly reduces the diameter of the wear spot

Hydrophobic Lightweight Cement with Thermal Shock Resistance and Thermal Insulating Properties for Energy-Storage Geothermal Well Systems

This study assessed the possibility of using polymethylhydrosiloxane (PMHS)-treated fly ash cenospheres (FCS) for formulating a thermally insulating and thermal shock (TS)-resistant cementitious blend with calcium aluminate cement. To prevent FCS degradation in an alkaline cement environment at high temperatures, the cenospheres were pre-treated with sodium metasilicate to form silanol and aluminol groups on their surface. These groups participated in a dehydrogenation reaction with the functional ≡Si–H groups within PMHS with the formation of siloxane oxygen-linked M-FCS (M: Al or Si). At high hydrothermal temperatures of 175 and 250 °C, some Si–O–Si and SiCH3 bonds ruptured, causing depolymerization of the polymer at the FCS surface and hydroxylation of the raptured sites with the formation of silanol groups. Repolymerization through self-condensation between the silanol groups followed, resulting in the transformation of siloxane to low crosslinked silicon-like polymer as a repolymerization-induced product (RIP) without carbon. The RIP provided adequate protection of FCS from pozzolanic reactions (PR), which was confirmed by the decline in zeolites as the products of PR of FCS. Cements with PMHS-treated FCS withstood both hydrothermal and thermal temperature of 250 °C in TS tests, and they also showed improved compressive strength, toughness, and water repellency as well as decreased thermal conductivity. The lubricating properties of PMHS increased the fluidity of lightweight slurries.

Effect of diamond-like carbon coatings alloying with chromium and molybdenum on the lubricating properties of oils during friction in pair with steel

The results have been presented of an experimental study of the tribological behavior of diamond-like carbon coatings (DLC) doped with chromium and molybdenum obtained by reactive magnetron sputtering. The effect of alloying with these metals on the tribological characteristics of boundary lubrication of a DLC coating/steel contact has been studied for the case of three model lubricants (inactive, surfactant, and chemically active). It has been shown that doping with chromium and molybdenum improves both the tribological characteristics of coatings under dry friction and the lubricating properties of the model oils, while alloying with molybdenum provides lower coefficients of friction and less wear at dry and boundary friction than alloying with chromium.