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Gear damage, e.g. scuffing, reacts sensitively to the local dissipation of frictional heat during a full gear mesh. Several empirical friction models have been established in relevant literature. These can be used to calculate the gear friction locally or averaged over a mesh. For calibration purpose, experimental data from twin disc machines with stationary contact conditions are mostly used. However, the assignment of the model as well as the consideration of topographical, rheological and geometrical effects is often subject to uncertainties. In this paper, a method is presented to measure the power losses of high-speed spur gears up to vt = 100 m/s. The measurement principle uses the calorimetric properties of the circulating lubricant. The implementation of the measurement setup in a highspeed gear test rig reduces thermal interferences from sealings and bearings. Analysis regarding the measurement quality show that the measurement method delivers reproducible results with a high measurement resolution over a wide range of operating conditions.

Wood is widely used in impact limiters of transport casks for radioactive material. Encapsulated by an outer and inner steel structure, spruce wood is often applied in layers of alternating direction. The friction at the interfaces between these layers is of crucial importance for the impact and energy absorption e.g., at an accidental impact of a cask against a hard component. In order to get detailed information for corresponding numerical calculations, in this study the friction coefficient for the combinations wood-wood and wood-steel was measured in the temperature range between -40 °C and 90 °C according to the relevant stress conditions for such casks. Results show decreasing friction with increasing temperature, ranging from 0.43 at -40 °C to 0.22 for 90 °C for wood-steel combinations and from 0.3 at -40 °C to 0.24 at 90 °C to for a wood-wood combination.

With the purpose of improving our predesign approach and increasing the end-product sustainability by going from resource wasting field testing to slender tribological model testing, we looked closer to commonly relevant calculation approaches as • Plint’s and Alliston-Greiner’s Energy Pulse (EP) • Matveesky’s friction power intensity (FPI) • Transmitted Energy (TE) to achieve fast and feasible tribo-system ranking for wind turbine bearing cases. With the concept of transmitted friction energy (Ef), satisfactory results were reached. We learned that 2-Disc tribometer may be used to simulate 100 % sliding, making comparison of different slippage rate easier by only using one tribometer, thus reducing measurement inaccuracies caused by different type of machines (e.g., pin on disc) or operator’s influence.

Sealless rolling bearings for use under media lubricated conditions are exposed to high tribocorrosive loads. To achieve the necessary wear resistance while keeping up the corrosion properties of the corrosion resistant steels low-temperature-plasma-diffusion-treatments were conducted. When scaling-up the developed low-temperature-plasma-nitriding-processes to industrial dimensions, it is necessary to reach the required surface conditions independently of the parts placement within the batch. Upscaling to industrial batch processes was analyzed by using the example of rolling bearings. To achieve a homogeneous treatment result, relevant factors like temperature distribution and component placement were taken into account. This allows to draw conclusions about the surface layer properties in dependence of temperature, batch arrangement and position within the batch to verify the treatment results homogeneity.

Thirteen carbon materials were tested as sorbent layers in bar adsorbent microextraction (BAμE) to monitor hint amounts of 10 common pharmaceutical compounds (PhCs) in surface and groundwater matrices such as surface and groundwater, saltwater, spring water, and sewage. The persistence of trace amounts of three organophosphate insect repellent and cis and trans permethrin (PERM) in water quality matrices is suggested using bar adsorptive microextraction in conjunction with microliquid dissolution accompanied by significant volume injection-gas chromatography-mass spectroscopic analysis able to operate in the particular ion monitoring acquisition mode. Using BAμE to compare several sorbent coatings (five porous carbon and six polymers), it was discovered that activated carbon (AC2) was the optimum compromise among specificity and effectiveness. 17-estradiol, estrone, sulfamethoxazole, diclofenac, triclosan, gemfibrozil, 17-ethinylestradiol, mefenamic acid, and clofibric acid were chosen as system drugs to represent different treatment groups. Despite their lower porosity, statistics revealed that low-T-activated hydrochars, made from carbohydrates and a eutectic salt mixture at constant temperature (e.g., 180°C) and autogenerated pressures, could compete at the top level commercially carbonaceous materials in this purpose. These L-T-activated hydrochars had the best overall recovery (between 21.8 and 83.5 percent) for the simultaneous analysis of ten targeted PhCs with very different physical and chemical possessions, utilizing higher-efficiency liquid chromatography diode array identification.

Deterministic contact modeling based on half-space theories has satisfied a wide range of applications. However, the half-space theories themselves do not involve shape effects of roughness on Green's functions/influence coefficients; in deterministic rough-surface contact analyses, the roughness is considered in gap function. This approach can be called the “roughness simplification”. One needs to answer two questions about the validity of the roughness simplification: How appropriate is the roughness simplification in modeling rough-surface contacts? How accurate can the commonly-included contact-plasticity behavior be captured under the roughness simplification? This work utilized a double-scale representation of an asperity--a microscopic deformable asperity stacked on a deformable half-space, to obtain their combined contact responses in both elastic and plastic regimes. The deformation and contact behaviors of asperities thus configured were obtained with finite element method (FEA) and rough-surface half-space contact solvers. Three stages of asperity contact were discovered: the Hertzian stage, the single-region elastoplastic stage, and the two-region elastoplastic stage where the surrounding base material also takes part in the contact. The comparisons of contact deformation and pressure results from both the FEA and half-space contact solvers support the validity of the half-space theories with the roughness simplification for various ellipsoid-shape asperities with circular-bases in both elastic and elastoplastic rough-surface asperity modeling. The research also reveals that when significant plastic deformations occur, asperities with different aspect ratios can bear different maximum elastoplastic contact pressures.

Micro- and nanotexturing on hard biomaterials have shown advantages for tissue engineering and antifouling applications. However, a growing number of studies have also shown that texturing may cause an increase in friction, demanding further research on the tribological effects of texturing under physiological conditions. This study investigates the tribological effects of micro- and nanopore patterns on hard hydrophilic silicon sliding against soft hydrophobic polydimethylsiloxane (PDMS) immersed in aqueous liquids with various viscosities, simulating the sliding of a textured implant surface against soft tissues. The experimental results show that silicon surfaces with pore textures at both micro- and nanoscale feature sizes confer a higher coefficient of friction (COF) than an untextured one. It is attributed to the texture's edge effect caused by the periodic pore patterns between the two sliding objects with a large difference in material stiffness. For the same solid area fraction, nanopored surfaces show a higher COF than micropored surfaces because of the significantly higher texture edge length per unit area. For micropored surfaces with a similar length of texture edge length per unit area, the COF increases more significantly with the increase in pore size because of the greater stress at the rims of the larger pores. The COFs of both micro- and nanoscale pores generally decrease from ∼10 to 0.1 with an increase in the surrounding aqueous viscosity, indicating the transition from a boundary lubrication to a mixed lubrication regime while mostly remaining in boundary lubrication. In contrast, the COF of an untextured surface decreases from ∼1 to 0.01, indicating that it mostly remains in the mixed lubrication regime while showing the tendency toward hydrodynamic lubrication. Compared to a hydrophilic hard probe sliding against a textured hydrophobic soft substrate, the hydrophobic soft probe sliding against a textured hydrophilic hard substrate produces a significantly higher COF under similar physiological conditions due to the larger edge effect.

In this research, AA2024 aluminum alloy-based surface composites was fabricated using ex-situ titanium boride particles (TiB2) as reinforcement using friction stir processing technique. Microstructural and mechanical variation with respect to addition of TiB2 onto AA2024 surface was studied and evaluated. Results proposed an increase in mechanical strength and hardness with respect to TiB2 addition when compared with the substrate metal. Dry sliding wear characteristics of aluminum surface composites at varying sliding distances (500m, 1000m, 1500m and 2000m) was analyzed using pin-on-disc apparatus. Wear resistance of developed surface composites improved comparatively with respect to substrate metal due to the combined effect of particle inclusion and friction stir processing. Characterization of worn out surface composites proposed that wear mechanism happens due to combination of abrasive and adhesive wear, while the major material removal happens due to abrasive wear.

Magnetic MgxCoyZn(1-x-y)Fe2O4 nanoparticles were successfully prepared by the rapid combustion approach, and SEM, XRD, VSM, EDX, and FTIR techniques were applied for their characterization. The influence of the element ratios (Mg2+, Co2+, and Zn2+) in magnetic MgxCoyZn(1-x-y)Fe2O4 nanoparticles on their properties was explored. To acquire a larger specific surface area for better adsorption of methyl blue (MB), magnetic Mg0.4Co0.5Zn0.1Fe2O4 nanoparticles calcined at 400°C for 2 h with 25 mL anhydrous ethanol were selected, and their average particle size and the saturation magnetization were about 81.3 nm and 13.5 emu·g-1, respectively. Adsorption kinetics models and adsorption isotherm models were applied to research the adsorption characteristics of MB onto magnetic Mg0.4Co0.5Zn0.1Fe2O4 nanoparticles. The pseudo-second-order kinetics model ( R 2 > 0.99 ) and Temkin isotherm model ( R 2 = 0.9887 ) were the most consistent with the data, indicating that the adsorption was the chemical multilayer adsorption mechanism, and the process was an exothermic reaction. The E of the Dubinin-Radushkevich (D-R) isotherm model was 0.2347 KJ·mol-1, indicating the adsorption involved physical adsorption besides chemical adsorption. The Δ G 0 and Δ H 0 ( Δ H 0 = − 10.38 KJ·mol-1) of the adsorption process of MB adsorbed onto magnetic Mg0.4Co0.5Zn0.1Fe2O4 nanoparticles measured through the thermodynamic experiment were both less than 0, which proved that the process was a spontaneous exothermic reaction. The adsorption capacity of MB onto magnetic Mg0.4Co0.5Zn0.1Fe2O4 nanoparticles increased with the pH of MB solution increasing from 2 to 4 at room temperature, and it had no significant change when the pH of MB solution was 4-12, while the relative removal rate was 98.75% of the first one after 2 cycles. The electrochemical impedance spectroscopy (EIS) and the cyclic voltammetry (CV) data further demonstrated that MB was adsorbed onto magnetic Mg0.4Co0.5Zn0.1Fe2O4 nanoparticles.

Hazardous heavy metal ions such as copper, zinc, nickel, chromium, cadmium, and lead engender a potential risk to human health. Among the processes involved in the retention of these contaminants, adsorption is advantageous for removing toxic metals because of its environmentally friendly aspect, efficiency, and low-cost operation. Information on the adsorption of heavy metals in soils from the semiarid region of northeastern Brazil is still scarce. In this study, the adsorption of heavy metals (Cd, Cu, Zn, Ni, and Pb) by a semiarid Brazilian bentonitic soil is investigated. This soil has been used as a bottom liner in an experimental municipal solid waste (MSW) cell located in Campina Grande, State of Paraíba, Brazil. The experimental cell consists of a landfill unit on an experimental scale, with the same constructive elements of a sanitary landfill. Disturbed and undisturbed samples of the investigated soil were collected at a quarry in the rural zone of Boa Vista (state of Paraiba, Northeast Brazil). Sorption attributes were determined via batch tests with a soil-solution ratio of 1 : 12.5 (4 g of dry soil to 50 mL of solution). Linear, Freundlich, and Langmuir isotherms were fitted to the experimental data, using as fitting parameters Pearson correlation coefficient ( R 2 ) and p value with a significance level α = 5 % . The ascending order of maximum adsorption capacity for heavy metals followed the series Ni