Taking the elliptical bearing as the research object, adopting the mixture two-phase flow model and energy equation, the pressure characteristics, the cavitation distribution and the thermal effect of elliptical bearing with different ellipticities are analyzed. The results show that the maximum temperature rise of elliptical bearing is lower than cylindrical bearing. The optimal ellipticity of elliptical bearing is 0.6, the upper and lower bush of elliptical bearing can form the effective oil film, the proportion of cavitation area and volume is small, the maximum temperature rise of oil film is lowest, which is conducive to the stable operation of journal bearings.

The microtexture with different morphological characteristics is obtained by changing the processing parameters of laser marking machine. The microtexture morphology characteristics are observed, and the width and depth of microtexture is measured. At the same time, the theoretical model of laser processing is established to solve the change rule of the processing morphology. The average friction coefficient variation of specimens obtained by different processing parameters is tested by universal friction and wear tester. The results show that the width of microtexture increases with the increase of laser processing power and decreases with the increase of laser scanning frequency, which is consistent with the theoretical results of laser processing. The depth of microtexture increases with the increase of laser processing power and scanning frequency. When the scanning times are 3, the width and depth of microtexture reach the maximum. With the decrease of scanning speed, the width and depth of microtexture increase gradually. Friction experiments show that when the processing power is 60–70 %, the lubrication can achieve the optimal value.

In the actual working condition, due to the manufacturing errors, improper installation, load, thermal deformation or other factors can cause the journal surface to produce the form and position errors. The mathematical models are developed that takes into account the form and position errors, the lubrication performance of four-recess capillary restrictor hybrid journal bearings with different journal tilt angles and cylindricities is studied, and the effect of eccentricity on the oil film lubrication performance is analysed. The results show that the dimensionless oil film pressure and loading capacity increase as the journal tilt angle and eccentricity increase considering journal tilt, and the friction coefficient tends to increase and then decrease. Compared with journal alignment, the oil film thickness distorts, the oil film pressure peak shifts to the edge of bearing, and the horizontal tilt has a greater impact on bearing when the journal is tilted. The oil film pressure distribution has no significant change considering cylindricity errors, while the oil film pressure value increases, the loading capacity increases and the coefficient of friction decreases as the cylindricity and eccentricity increase. The research shows that the presence of a certain cylindricity error contributes to the lubrication performance of four-recess capillary restrictor hybrid journal bearings.

Purpose Researchers have not reached an agreement on which biomimetic shape has the best lubrication performance. This paper aims to study the influence of microtexture size, shape and direction on bearing capacity, end leakage, friction coefficient and wear of oil film. Design/methodology/approach Different oil film thickness equations considering the microtexture of bearing surface are gained. The two-dimensional finite difference equation and the calculation equation of wear are established. Findings The theoretical research shows that the wear value and the wear ratio when long side is perpendicular to the axial direction of the bearing are generally lower than when the long axis is parallel to the axial direction of bearing. The theoretical and experimental results show that the appropriate microtexture shape, such as circular dimple, crescent-shaped dimple, triangular dimple and fish-shaped dimple can improve effectively the lubrication performance of journal bearing and reduce the friction coefficient. Originality/value The research has great significance to reduce friction and improve the wear resistance of equipment.

The aim of this work is to study the strengthening mechanism and thermal stability of spray formed H13 steel. The microstructure and hardness of spray formed H13 steels are investigated by electron microscopy, transmission electron microscopy and hardness measurementscanning. The calculated results demonstrate that tensile strength, impact energy and hardness values of sprayed-formed H13 steel are higher than that of as-cast H13 steel when the tempering temperature is 600 °C after quenched at 1050 °C. Compared with as-cast H13 steels, tempered spray-formed H13 steels possess supernal high-temperature temper resistant stability. The chemical composition of the carbides in spray-formed steels is V and Cr rich spherical carbides are hardly influenced by the tempering treatment.