In this paper, shot peening (SP) was employed as a post-processing technique for the laser surface melted (LSMed) gear. The aim was to improve the contact fatigue performance of laser surface melting+shot peened (LSMSPed) gears. The microstructure, surface roughness, residual stress, microhardness of C40 steel gears before and after SP treatment were characterized using scanning electron microscopy, x-ray diffraction stress analyzer, contour measuring instrument, and hardness tester. Fatigue test of gear was carried out with a Forschungsstelle für Zahnräder und Getriebebau (FZG) testing machine. Following the laser surface melting (LSM) treatment, a molten layer was observed on the gear teeth surface. The experimental results indicated that SP induced a hardened layer with a certain thickness and plastic deformation on the surface of LSMed gears. Importantly, as the SP parameters increased, there’s a corresponding reduction in both the average grain diameter and the maximum grain diameter. The reduction was most pronounced when the shot diameter reached its maximum value. It’s worth noting that once the optimal threshold for SP parameters is surpassed, the residual compressive stress and microhardness on the LSMSPed gear surface do not exhibit a continuous growth trend. Furthermore, the rise in SP parameters resulted in a gradual increase in the surface roughness of LSMSPed gears, albeit to varying degrees. In light of the combined effects of grain refinement, residual compressive stress, microhardness, and surface roughness, the contact fatigue performance of LSMSPed gears improved with increasing SP parameters. Notably, when comparing the contact fatigue life of LSMed gears with that of LSMSPed gears, we observed a substantial enhancement. However, it’s essential to highlight that when the shot diameter reaches its maximum value, the contact fatigue life of the LSMSPed gear, somewhat unexpectedly, decreased. It emphasized to a certain extent the influence of surface roughness on the contact fatigue performance of LSMSP gears.

Ni/B₄C/TiC coating was prepared using laser cladding technology with 45 steel as substrate material. The effects of different scanning speeds on phase composition, microstructure, microhardness, and tribological properties were investigated. It was found that the coating is primarily composed of Fe₃B, Fe₃C, B₂Fe₃Ni₃, TiC, and solid solution of [Fe, Ni]. TiC particles are not completely dissolved, which promotes grain refinement. The microhardness increases with the increase in scanning speed and reaches the maximum value at 240 mm/min. The wear resistance test revealed that the coating exhibited the best wear resistance at 240 mm/min. The main wear mechanisms were fatigue wear, abrasive wear, and a small amount of oxidative wear.

This paper investigated the microstructure and composition of Argopecten irradians through X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy spectrometer (EDS), and measured the hardness and tribological properties of Argopecten irradians using nanoindentation and friction wear testing machine. The results showed that Argopecten irradians mainly contained carbon, calcium and oxygen, and existed in the mineral phase. There were many radial ribs on the surface of Argopecten irradians shell. The microstructure of Argopecten irradians was crossbedded. The surface hardness and elastic modulus of Argopecten irradians were 0.094 and 5.85GPa, respectively. With an increase in the cross-section distance, the hardness and elastic modulus of Argopecten irradians decreased gradually, and there was an obvious gradient for the mechanical properties. When the temperature was below 200°C during heat treatment, the hardness and elastic modulus of Argopecten irradians first changed slightly and then increased gradually. Under water lubrication conditions, the frictional coefficient of Argopecten irradians / silicon nitride friction counterparts was greater than that of the dry friction condition. This research provided the bionic basis for the compressive composite materials and anti-friction surface design.