Coatings with a thickness from ~40 to ~50 µm on Ti6Al4V titanium alloys were formed by plasma electrolytic oxidation (PEO) in a silicate-hypophosphite electrolyte with the addition of graphene oxide. The PEO treatment was carried out in the anode–cathode mode (50 Hz) at a ratio of anode and cathode currents of 1:1; their sum density was 20 A/dm², and the treatment’s duration was 30 min. The effect of the graphene oxide’s concentration in the electrolyte on the thickness, roughness, hardness, surface morphology, structure, composition, and tribological characteristics of the PEO coatings was studied. Wear experiments, under dry conditions, were carried out in a ball-on-disk tribotester with an applied load of 5 N, a sliding speed of 0.1 m·s⁻¹, and a sliding distance of 1000 m. According to the obtained results, the addition of graphene oxide (GO) into the base silicate-hypophosphite electrolyte leads to a slight decrease in the coefficient of friction (from 0.73 to 0.69) and a reduction in the wear rate by more than 1.5 times (from 8.04 to 5.2 mm³/N·m), with an increase in the GO’s concentration from 0 to 0.5 kg/m³, respectively. This occurs due to the formation of a GO-containing lubricating tribolayer upon contact with the coating of the counter-body in the friction pair. Delamination of the coatings during wear occurs due to contact fatigue; with an increase in the concentration of GO in the electrolyte from 0 to 0.5 kg/m³, this process slows down by more than four times.

The results of an experimental study of the effect of the normal pressure in the range of 0.1–0.3MPa, a velocity of sliding of 1–100 mm/s, and a bulk temperature of 22 to–27°C on the coefficient of...

A new sensor for estimating elasticity of soft tissues such as a liver was developed for minimally invasive surgery application. By measuring deformation and adjusting internal pressure of the pneumatic sensor head, the sensor can be used to do palpation (indentation) of tissues with wide range of stiffness. A video camera installed within the sensor shell is used to register the radius of the contact area. Based on finite element model simulations and the measured data, elastic modulus of the indented soft tissue can be calculated. Three phantom materials, namely plastic, silicone and gelatin, with varied stiffness were tested. The experimental results demonstrated that the new sensor can obtain highly reliable data with error less than 5%. The new sensor might be served as an instrument in laparoscopic surgery for diagnosis of pathological tissues or internal organs.

A method for evaluating the tribological parameters and service life of the piston-cylinder tribosystem of a diesel engine based on calculations and experimental studies is presented. This approach...

An experimental methodology for constructing a 3D friction map, which depends on normal pressure, sliding velocity, and temperature, for tire tread rubber has been presented. The methodology of...