Fabric laminated composites with excellent mechanical strength and brake stability are now developed as promising wet friction materials. However, facing the serious challenge of persistent operation under harsh conditions, the resistance and interlaminar bonding properties of laminated composites urgently require further improvement. In this study, methylene diphenyl diisocyanate (MDI) was chemically grafted onto a carbon fiber powder (CFP) surface via an oil bath for surface functionalization. Fabric laminated composites modified with functionalized CFP (CFP-MDI) were subsequently fabricated by sedimentation to construct a “brick and mortar” structure. As a result, the comprehensive performance of laminated composites was effectively promoted by the introduction of CFP-MDI as a mortar. In particular, owing to the conspique synergistic effect between CFP and MDI, the interlaminar shear strength (ILSS) of the modified laminated composite increased by 17.93%, and the wear rate decreased by 38.18%, from 7.91×10⁻¹⁴ to 4.89×10⁻¹⁴ m³/(N·m), demonstrating the excellent ability of the modified composite to efficiently suppress crack and local damage propagation. This work provides a new strategy to achieve the integrated construction of toughening interlaminated and wear-resistant coatings, which is conducive to the large-scale application of laminated fabric composites in the friction transmission braking field.

To meet the increased demand for light-weight and high-performance special-shaped load bearing parts in automotive industry, the short carbon fiber reinforced magnesium matrix composite (C_sf/Mg) part with complex configuration features and abrupt cross-sectional transitions was fabricated by liquid-solid extrusion following vacuum pressure infiltration process (LSEVI). Near-net forming schemes of both the special-shaped fiber preform and composite part were proposed. The effect of process parameters on the forming quality of the composite part was discussed. Meanwhile, the microstructures and compressive properties in different regions of the part were analyzed. The results show that the forward forming scheme provides the special-shaped fiber preform with no surface defects. For the C_sf/AZ91D part, its internal microstructures show that the infiltration of liquid magnesium is sufficient and uniform. The compressive strength of the composite part can reach up to 487 MPa, corresponding to ∼40% increase compared to 335 MPa of the AZ91D alloy. The average compressive strain of composites is less than 10%, which is about 50% of that of the AZ91D alloy. When the fiber orientation is parallel to the shear direction on the shear plane, the load-bearing capacity of the fiber is much higher than that of the fiber perpendicular to the shear direction. This work not only provides a convenient approach to fabricate special-shaped preform with high fiber volume fraction, but also gives a demonstration for the near-net forming of C_sf/Mg parts with excellent material isotropy and compressive properties.

Mg alloy matrix composites reinforced with short carbon fibers (C_sf/Mg) are considered as potential candidates for integrated structural-functional electronic parts that satisfy the requirements of lightweight, excellent mechanical properties, and heat dissipation. However, the different characteristics of C_sf and Mg alloy make the interface a critical issue affecting the synergistic improvement of thermal and mechanical properties of the composites. Here, Cu coating with different thicknesses is introduced to modify the C_sf/Mg interface, so as to simultaneously enhance the thermal and mechanical performances, which can combine the advantages of coating modification and matrix alloying. Results reveal that thermal diffusivity (TD) of 3-C_sf-Cu/Mg composites is as high as 22.12 mm²/s and an enhancement of 52.97% is achieved compared with C_sf/Mg composites, as well as 16.3% enhancement of ultimate compressive strength (UCS) in the longitudinal direction, 8.84% improvement of UCS in the transverse direction, and 53.08% increasement of ultimate tensile strength (UTS). Such improvement can be ascribed to the formation of intermetallic compounds. The formation of intermetallic compounds can not only effectively alleviate the lattice distortion of the matrix and decrease interfacial thermal resistance, but also bear the loads. Our work is of great significance for designing C_sf/Mg composites with integrated structure and function.

Graphene nanoplates (GNPs) and carbon nanotubes (CNTs) can construct efficient thermal flux channels in composites, which is becoming one of the effective methods to improve thermal conductivity (TC) of composites. In this paper, an emerging class of GNPs&MWCNTs preform with 3D orientated structures were prepared by using electrostatic self-assembly and directional freeze-drying methods, and then fabricated the GNPs&MWCNTs reinforced AZ91D magnesium (GNPs&MWCNTs/AZ91D) composites by squeeze casting process. To ensure the well preparation of the composites, the GNPs&MWCNTs preforms need to possess enough compression strength to withstand squeezing pressure. Therefore, the effects of the electrostatic self-assembly process, directional freeze drying process and thermal reduction process on the compression strength of 3D structure GNPs&MWCNTs preforms were studied. The compression strength of GNPs&MWCNTs preforms were well improved to 98 KPa, which were used for the fabrication of AZ91D matrix composites. The TC of 0.5 wt.% (1:1) GNPs&MWCNTs/AZ91D composites reached 71.7 W/(m·K) in the freezing direction, which was 41.8% higher than that (50.6 W/(m·K)) of the AZ91D alloy. This work provides a novel method for preparing GNPs&MWCNTs/AZ91D composites with improved TCs.