Laser cladding technology is widely used in component repair and surface strengthening because of its advantages of various powder options and high processing efficiency. This paper outlines the application and research of transition layers in laser cladding and details the advantages of transition layers in terms of bonding performance, defect rate, and cladding thickness. Compared with conventional laser cladding, the composite process with the addition of transition layer has been further improved in terms of organization, mechanical properties, and corrosion resistance. In addition, the repair process of laser cladding to meet the cladding thickness of the parts and avoid the degradation of surface properties is also discussed.

The polymer liner of the hydrogen storage cylinder was studied to investigate better hydrogen storage capacity in Type-IV cylinders. Molecular dynamics methods were used to simulate the adsorption and diffusion processes of hydrogen in a graphene-filled polyamide 6 (PA6) system. The solubility and diffusion characteristics of hydrogen in PA6 systems filled with different filler ratios (3 wt%, 4 wt%, 5 wt%, 6 wt%, and 7 wt%) were studied under working pressures (0.1 MPa, 35 MPa, 52 MPa, and 70 MPa). The effects of filler ratio, temperature, and pressure on hydrogen diffusion were analyzed. The results show that at atmospheric pressure when the graphene content reaches 5 wt%, its permeability coefficient is as low as 2.44 × 10⁻¹³ cm³·cm/(cm²·s·Pa), which is a 54.6% reduction compared to PA6. At 358 K and 70 MPa, the diffusion coefficient of the 5 wt% graphene/PA6 composite system is 138% higher than that at 298 K and 70 MPa. With increasing pressure, the diffusion coefficients of all materials generally decrease linearly. Among them, pure PA6 has the largest diffusion coefficient, while the 4 wt% graphene/PA6 composite system has the smallest diffusion coefficient. Additionally, the impact of FFV (free volume fraction) on the barrier properties of the material was studied, and the movement trajectory of H₂ in the composite system was analyzed.

Laser cladding technology has become one of the most effective surface modification technologies to date due to its high energy density, small heat affected zone, low dilution rate and high cooling rate. However, with the increasing demand for products, the uneven tissue distribution, cracks, pores and other defects of the clad layer seriously limit its application and development. The performance and surface quality of the cladding layer need to be further improved. On this basis, the effects of different energy fields, such as electromagnetic fields, ultrasonic fields and induction heating, on the tissue properties of coatings are outlined and the mechanisms of the effects of various auxiliary technologies on the tissue properties and tissue transformation mechanism are reviewed. In addition, different posttreatment processes (heat treatment, surface strengthening, etc.) of laser cladding coatings are reviewed, providing a reference for further improvements in the microstructure and properties of the cladding layer and discussing existing problems and future development directions.

Laser cladding uses a high-energy laser beam as a heat source to rapidly melt and solidify the cladding material onto the substrate to form a high-performance coating. This technology provides an efficient and economical method to repair and remanufacture precision equipment such as engines and spacecraft. However, the inherent non-equilibrium solidification properties of laser cladding often lead to problems such as coating anisotropy, high porosity, and elemental segregation. Optimizing process parameters and heat treatment do not always eliminate these defects. Therefore, it is necessary to seek a more appropriate solution. Introducing laser remelting on the surface or between the layers of the coating to cause it to remelt and redistribute can refine the grain size, reduce defects, and improve the uniformity of the composition, thus enhancing the performance of the coating. This paper reviews and summarizes the application and development status of laser remelting technology in laser cladding and discusses it in terms of surface quality, hardness, wear resistance, and corrosion resistance of the coating. It also identifies the potential of external field-assisted laser remelting technology in further optimizing coating performance. Finally, based on the review, suggestions are provided for selecting remelting parameters.