Inhomogeneous structures with carbon nanotubes (CNTs), reinforced with Cu composite foams as the reinforcing skeletons (CNTs/Cu_f^®Cu), have been designed to overcome the paradox between strength and ductility or conductivity in copper matrix composites. The interface between CNTs and the copper matrix is usually weak, due to poor wettability and interaction. In this study, nickel nanoparticles are decorated onto CNTs to improve interfacial bonding. The broader interface transition area between CNTs and copper with Ni₃C interfacial products formed, and a combination of improved electrical conductivity (95.6% IACS), tensile strength (364.9 MPa), and elongation (40.6%) was achieved for the Ni-decorated CNTs/Cu_f^®Cu (Ni-CNTs/Cu_f^®Cu). In addition, the strengthening mechanisms are discussed in this study.

Carbon nanotubes (CNTs) reinforced double-layered Cu-Ni composite foams (Cu-Ni/CNT foams) were prepared through chemical plating and electrodeposition, for the purpose of combining enhanced mechanical and electromagnetic shielding properties. The microstructure characterization revealed a quite uniform dispersion of the CNTs embedded in the metal layers, even after heat treatments. The property testing showed the compressive strength, energy absorption capacity and electromagnetic shielding effectiveness (SE) of Cu-Ni/CNTs foams were significantly improved, as compared to Cu-Ni foams. The heat treatments of the composite foams resulted in an interdiffusion of the Cu and Ni layers, causing an increase of compressive strength and a slight decrease of average SE. The possible mechanisms of the property evolution are discussed.

During the laser-based directed energy deposition (DED-LB) processing, a WC-12Co composite coating with high hardness and strong wear resistance was successfully prepared on a 316L stainless steel substrate by adopting a high-precision coaxial powder feeding system using a spherical WC-12Co composite powder, which showed a large number of dendritic carbides and herringbone planar crystals on the substrate-binding interface. The influences of laser power on microstructural and mechanical properties (e.g., hardness, friction resistance) of WC-12Co composite surfaces were investigated. The results show that laser power has a significant effect on determining the degree of Co phase melting around the WC particles and the adhesion strength between the matrix and the coating. Lower laser power does not meet the melting requirements of WC particles, thus weakening the molding quality of the composite coating. At high laser power, it is possible to dissolve the WC particles and melt the metal powder between the particles, thus improving the material properties. The laser power increased from 700 W to 1000 W and the average hardness of the coating surface gradually increased from 1166.33 HV to 1395.70 HV, which is about 4–5 times higher than the average hardness of the substrate (about 281.76 HV). In addition, the coatings deposited at 1000 W showed better wear resistance. This work shows that the processing parameters during laser-directed energy deposition can be optimized to prepare WC-12Co composite coatings with excellent mechanical properties.

Ni60/60% WC composite coatings with a good surface roughness and high mechanical properties were successfully prepared on 316L stainless steel substrate by laser-directed energy deposition (LDED) technology. The effects of laser power on the microstructural evolution and mechanical properties of the Ni60/60% WC composite coating were investigated. The relationships between the chemical composition, the microstructure, the hardness, and the friction wear resistance of the composite coatings were characterized and investigated. The results show that the laser power had a significant effect on the energy input, which determined the melting extent of the Ni60 phases around the WC particles and the bonding strength between the reinforcements and the matrix, as well as the bonding strength between the substrate and the coatings. With an increase in the laser power from 800 W to 1400 W, the average hardness of the coating surface increased due to the increased densification of the deposited coatings and then decreased due to grain coarsening under a high energy input. The average coefficient of friction of the coatings decreased gradually to 0.383 at 1000 W, showing a minimum wear of 0.00013 mm² at 1200 W. The main wear mechanisms on the coated surfaces were adhesive wear and abrasive wear. Moreover, the coatings deposited at 1200 W exhibited better forming quality and wear resistance. This work suggests that the processing parameters during LDED can be optimized to prepare Ni60/60% WC wear-resistant coatings with excellent mechanical properties.

The laser drilling of carbon steel is always suffered from the formation of slag, the presence of cutting burrs, the generation of a significant quantity of spatter, and the incomplete penetration of the substrate. In order to avoid these defects formed during the laser drilling of carbon steel, the COMSOL multi-physics simulation method was used to model and optimize the laser drilling process. Considering the splash evolution of the material during the complex drilling process, the transient evolution of the temperature field, the flow of the molten fluid, the geometrical changes, and the absorption of the laser energy during the laser drilling process were investigated. The simulated borehole dimensions are consistent with the experimental results. The process parameters have a great influence on the fluid flow pattern and material slag splashing. The laser power has a significant effect on the laser processing compared with the process parameters. With the increase in laser power and the decrease in laser heat source radius, the time required for perforation is reduced, the flow of melt is accelerated, the perforation efficiency is increased, and the hole wall is smoother, but the degree of spattering is greater. The optimized process parameters were obtained: laser heat source radius of 0.3 mm, laser power of 3000 W. These findings can help reduce the machining defects in carbon steel with excellent mechanical properties by optimizing the laser drilling processing parameters.