Self-generated TiC particle reinforced FeCrCoNiTiAlBC high entropy alloy coating with a thickness of 1.5 mm was cladded on the surface of 45# steel by a semiconductor laser. Results show that fine grain TiC particles have been self-generated in the coating with the increase of the additions of C and B elements from 2 to 4 wt. %. The base crystal structure of the coating was found to change from a body-centered-cubic solid solution to a face-centered-cubic (FCC) solid solution with the increase in the addition of B and C. The TiC particles have irregular quadrilateral and flower morphologies, and the average hardness of the coating is 560 HV. The cracking tendency of the coating has been significantly reduced, which is attributed to the formation of the self-generated fine TiC particles and the FCC solid solution matrix.

Spherical 24CrNiMo alloy steel powder used for selective laser melting (SLM) fabricating high-speed train brake disc was prepared by the vacuum induction melting gas atomisation (VIGA) method. Powder morphology, particle size, flowability and microstructure were measured. Part properties fabricated by SLM were investigated via some modern analysis method. The experimental results showed that powder mean particle size D₅₀ was 75 μm, flowability was 16.69 s/50 g and apparent density was 4.71 g cm⁻³. 24CrNiMo alloy steel specimen microstructures prepared by SLM consisted of proeutectoid ferrite and granular bainite. Average microhardness was 346 HV, tensile strength was 1223 MPa, extensibility was 13.1% and the product of strength and elongation was 16.1 GPa%. 24CrNiMo alloy steel powder prepared by the VIGA method had good laser printability and huge potential application value for SLM-fabricated brake disc.

Self-lubricating composite material sleeves were prepared using a powder matrix of 663-tin bronze powder in which boron nitride (BN) of 0 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, and 6 wt% was added as a lubricating phase. The microstructure, mechanical properties, and tribological performance of the samples were studied using optical microscopy, scanning electron microscopy, hardness tests, tensile tests, and wear tests. The results show that the density, hardness, and compressive strength of the samples each decrease gradually with the increase of BN content, and porosity increases with the increase of BN content. The friction coefficient and wear loss both reduced after BN was introduced in the Cu alloy matrix due to BN forming a lubricating film on the friction surface. With a BN content of 2 wt%, the sleeve showed the best combination of properties with a hardness of 55 HV, crushing strength of 302 MPa, density of 7.069 g/cm³, a relatively small friction coefficient and lowest wear loss. The new copper-based/BN self-lubricating composite material has good prospects for application in the manufacturing of frictional sleeves of high-speed sewing machinery.

Hybrid Ni-P alloy plating coating containing nano-A1₂O₃ and polytetrafluoroethylene (PTFE) particles on the substrate of 45 steel has been prepared by an electroless plating method. The microstructure, microhardness, and wear resistance of the composite plating coating were analyzed using a microhardness tester, optical microscope, scanning electron microscopy, X-ray diffraction, and friction-wear tester. The results show that the Ni–P–PTFE–nano-Al₂O₃ composite plating coating with high wear resistance and a low friction coefficient, made by the combination of 3g/L nano-A1₂O₃ and 10 mL/L PTFE particles in plating solution, was responsible for enhancing tribological and lubricating properties on the 45 steel surface. The microhardness of the Ni-P-PTFE-nano-Al₂O₃ amorphous coating was HV452; its hardness was correspondingly increased and reached HV756 with a heat treatment at 350°C for 1 h, with the PTFE particles in the coating undestroyed. Simultaneously, the wear loss was 1.6 mg and the friction coefficient was 0.11, the cooperative effect of both particles enabled the Ni-P-PTFE-nano-A1₂O₃ composite coating to have highly wear-resistant and lubricating properties.