Springer Science and Business Media LLC

Two types of lithium greases were fabricated by using PAO and polyol ester as two base oils. The friction tests for the lithium soap-based greases were performed under different operating conditions by mini-traction machine, and the data were compared and analysed. The results show that when the lithium-based soap thickens different types of base oils with the same viscosity, the greater the elastohydrodynamic friction coefficient of the base oil, the greater the elastohydrodynamic friction coefficient of the grease. In a low-speed bearing or contact pair, both base oil and thickener go through the contact zone to contribute to the friction of the grease. When the same lithium-based thickener thickens the different base oils, the greater the interactions between the base oil molecules, the greater the interactions between the base oil molecules and the thickener molecules, the wider the soap fibres, and the greater the friction coefficient of the grease. The friction coefficient of oil PAO–lithium-based soap grease is higher than that of its base oil PAO. The friction coefficient of oil polyol ester–lithium-based soap grease is less than that of its base oil polyol ester when the viscosities of the two base oils are 68 mm2/s.

This work presents the suggestion of a model for the prediction of the reliability of type III gas storage vessel under pressure, considering the geometrical and mechanical uncertainties using the Monte Carlo method. Using the hoop stress for each ply, the Monte Carlo method was used to predict the distribution function of the mechanical response. The random design variables of the aluminum liner; which is overwrapped by a composite manufactured by filament winding. Nine random design variables with uncertainties were selected, namely: elastic constants of metallic and composite materials, ply angles, thickness, and finally the mechanical loading (pressure). To ensure the accuracy of the obtained results, we have performed 105 simulations. The obtained results showed that the elastic properties of the composite materials have no significant influence on the security of the composite vessels type III in relation to the manufacturing parameters: which are thickness, winding angle, and the loading pressure. The probability of failure increased significantly when all the random variables were considered simultaneously.

High-pressure torsion (HPT) is an established material strengthening technique through severe plastic deformation. Expanding its strengthening capabilities requires an appropriate deformation control. Unlike the thoroughly reviewed associated strengthening parameters like sample and processing variables, limited information concerning the apparatus variables is available due to the high experimental cost. This limitation was addressed in this present work by conducting parametric analysis through finite element simulation. This study examined the effects of anvil parameters, including the free flow gap between anvils, anvil wall inclination angle and anvils alignment, on the stress characteristics during HPT. The systematic analysis revealed that the free flow gap, $$j$$ of 1 mm, leads to a heterogeneous pressure distribution across the sample radius. However, the pressure homogeneity depends slightly on the wall inclination angle, $$\beta $$ . In particular, $$j\le $$ 0.2 mm and $$\beta \le $$  10° could generate continuous strengthening behaviour with the applied strain. Furthermore, misalignment also demonstrated contributing to the disc centre strengthening, a critical explanation that the fundamental torsion test formula could not describe. The presented parametric analysis through a computer-aided numerical computation serves as an effective deformation control and optimisation. It complements the existing theory and experimental findings at a minimal computation cost.

Open-loop hydronic heating systems have been found to provide a breeding ground for bacteria, including bacteria associated with microbiologically influenced corrosion (MIC). Microbiologically influenced corrosion of brass fittings, which may contain up to 8% lead in potable water applications, has been linked to high copper and lead levels in water samples taken from the hydronic-loop tubing. The contamination is likely concentrated in slime deposits found within the tubing. These slime deposits can enter the potable water supply, resulting in potential copper and lead exposure levels considerably above Environmental Protection Agency (EPA) guidelines. The authors recommend that hydronic heating systems incorporate a closed-loop design to prevent personal exposure and to provide for use of corrosion-inhibiting additives.

The corrosion inhibition of nickel in 0.5 M H2SO4 by cysteine was investigated with various electrochemical methods and surface observations by SEM. The cyclic voltammetry revealed that the current density is the highest in absence of the cysteine and decreases with increasing inhibitor concentration. The cysteine is an anodic inhibitor. The polarization and electrochemical impedance spectroscopy showed that the cysteine has a poor inhibitive effect. The surface observation by scanning electron microscope corroborates the addition of cysteine has no significant improvement of the surface morphology of nickel electrode in 0.5 M H2SO4. Results obtained by different methods corroborate each other.

X-ray diffraction topography is a new tool that may help fractographic analysis of single-crystal structural materials. It is sensitive to local strain and/or crystallographic orientation and provides a unique view of single-crystal samples both before and after fracture. It can find strength-and performance-limiting surface and subsurface flaws that are undetectable by other methods or are detectable only with great difficulty and provides a complementary view of the fracture surface. The attributes of synchrotron-based X-ray topography as applied to fractography are described and illustrated with examples from recent experiments on sapphire.