Investigation of electromagnetic wave absorption and anti-corrosion mechanism of multifunctional Ni/AlN composite coatings with core-shell structure by laser cladding

Abstract

Developing efficient microwave absorbing materials (MAMs) suitable for prolonged use in marine environments is of great importance. Laser cladding serves as one of the new techniques for the material of surface modification and microwave-absorbing materials in the 3D printing. However, it is usually challenging to prepare materials that combine desirable printability, corrosion resistance, and microwave absorption properties using this technology. To enhance the microwave absorption of laser-clad Ni-based alloys, the method of impedance modulation was employed by incorporating ceramic powders with varying AlN content. The results show that Ni/AlN/MWCNTs composite functional materials with core-shell heterostructures were prepared under optimized laser processing parameters. This unique core-shell structure optimizes impedance matching increased polarization loss and multiple scattering to boost microwave absorption. The optimized 20wt% AlN content resulted in a minimum RL of -13.24dB at 13.86GHz, in addition, electrochemical tests showed that AlN enhanced the resistance to the corrosion medium transfer during the corrosion process, and the corrosion resistance of the Ni/AlN/MWCNTs composites material (self-corrosion current density (8.52 × 10-8), the charge transfer resistance (1.55 × 10-5)). Therefore, this work provides innovative theoretical and practical insight for the design and manufacture of advanced microwave-absorbing materials for harsh environments by laser melting technology.