The formation of highly thermally conductive composites with a three-dimensional (3D) oriented structure has become an important means to solve the heat dissipation problem of electronic components. In this paper, a carbon fiber (CF) felt with a 3D network structure was constructed through the airflow netting forming technology and needle punching. The carbon fiber/phenolic composites were then fabricated by CF felt and phenolic resin through vacuum impregnation and compression molding. The effects of CF felt content and porosity on the thermal conductivity of carbon fiber/phenolic composites were investigated. The enhancement of carbon skeleton content promotes the conduction of heat inside the composites, and the decrease of porosity also significantly improves the thermal conductivity of the composites. The results indicate that the composites exhibit a maximum in-plane thermal conductivity of 1.3 W/mK, which is about 650% that of pure phenolic resin, showing that the construction of 3D thermal network structure is conducive to the reinforcement of thermal conductivity of composites. The method can provide a certain theoretical basis for constructing a thermally conductive composite with a three-dimensional structure.

Pure nickel (Ni), TiB2 reinforced nickel (Ni-TiB2), nickel-phosphorus (Ni-P), and TiB2 reinforced nickel-phosphorus (Ni-P-TiB2) composite coatings were deposited on AISI-1045 steel substrates from Watts bath and phosphorous-containing solution, respectively. The composition and microstructure of these coatings were analyzed by energy dispersive X-ray spectroscopy (EDS), scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis. The properties of these coatings, including hardness, were assessed and compared. The electrochemical performance of these coatings was investigated in a 3.5 wt. % sodium chloride solution using electrochemical spectroscopy (EIS) and the potentiodynamic polarization technique at room temperature. The effect of TiB2 on the microstructure, phase, and properties of the coatings was investigated. The results indicate that the incorporation of TiB2 particles in the nickel matrix greatly increased the hardness and anti-corrosion properties of the nickel coatings by refining of the microstructure and reducing the defects. The enhancement effect of TiB2 on Ni-P coating is not as significant as that of TiB2 on nickel coating. However, with the incorporation of TiB2 ceramic particles, the corrosion resistance and hardness of the Ni-P-TiB2 coating increased by about 50% and 10%, respectively, compared with the original Ni-P coating. The present study provides insight into the potential applications of novel TiB2 ceramic particle-reinforced nickel composite coatings in the areas of wear and corrosion resistance.

Lightweight concrete is one of the effective means to solve the problems of structural component weight, energy efficiency, and fire safety in modern civil engineering. Heavy calcium carbonate-reinforced epoxy composite spheres (HC-R-EMS) were prepared by the ball milling method, and HC-R-EMS, cement, and hollow glass microspheres (HGMS) were mixed into the mold by the molding method to prepare composite lightweight concrete. The relationship between the HC-R-EMS volumetric fraction, the initial inner diameter of the HC-R-EMS, the number of layers of HC-R-EMS, the HGMS volume ratio, the basalt fiber length and content, and the multi-phase composite lightweight concrete density and compressive strength was studied. The experimental results show that the density of the lightweight concrete ranges between 0.953–1.679 g/cm3 and the compressive strength ranges between 1.59–17.26 MPa, where the volume fraction of HC-R-EMS is 90%, the initial internal diameter is 8–9 mm, and the number of layers of HC-R-EMS is three. The lightweight concrete can meet the requirements of high strength (12.67 MPa) and low density (0.953 g/cm3). In addition, the addition of basalt fiber (BF) can effectively improve the compressive strength of the material without changing the density of the material. From a micro-level perspective, HC-R-EMS is closely combined with the cement matrix, which is conducive to increasing the compressive strength of concrete. Basalt fibers connect the matrix into a network, improving the maximum limit force of the concrete.

Metal matrix composite coatings have attracted scientific and engineering interest because of their excellent mechanical properties. Nano-Si3N4 reinforced nickel coatings with different ceria contents were fabricated by electrodeposition. The microstructures, hardness, and tribological properties as well as corrosion behaviors of the composite coatings were studied in detailed. The results show that incorporation of ceria nanoparticles into the nickel matrix can decrease the grain size and facilitate the (111) texture of the coatings, leading to a smooth surface, compact microstructure, and dispersion-strengthening composites. The 6CeO2 coating with the highest hardness of 520 HV50g demonstrates the best wear resistance, while the 3CeO2 coating shows the best corrosion resistance with the smallest i corr value of 0.0972 μA/cm2. The study suggests a significant improvement in mechanical and anti-corrosion properties by incorporation with the ceria nanoparticles, which has important implications for the surface protection of engineering materials.