RESUMEN
Titanium matrix composites (TMCs) have garnered substantial attention from researchers owing to their outstanding properties. Nonetheless, the strength and ductility of TMCs hardly co-exist and often show a trade-off between each other. In this study, we employ an ultra-thin graphite powder sheet as the carbon source and employ Ti/C composites with varying carbon contents, prepared via a layer-stacked laminated sintering method, to ensure a comprehensive in-situ reaction and uniform reinforcement distribution. With increasing carbon content, noticeable alterations occur in the size, concentration, and morphology of the titanium carbide (TiC) particles. The increase of TiC particle content is found to boost the ultimate tensile strength of the composite. However, this improvement comes at the expense of reduced elongation. Notably, as the carbon content reaches 1.81 wt%, the yield strength and ultimate tensile strength of the composites soar to 354.4 MPa and 575.4 MPa, respectively. These values represent a remarkable increase of 75.4% and 65.0% compared to pure titanium, while maintaining an acceptable elongation of 6.45%. This study unveils a promising approach for significantly enhancing the mechanical properties of titanium alloys.
RESUMEN
Titanium matrix composites (TMCs) with TiC reinforcements were fabricated by an in-situ method that evolves pure titanium foils (thick: 100 µm) and graphite powder sheets by spark plasma sintering. 20 µm thick graphite powder sheets with PVA (polyvinyl alcohol) were fabricated as carbon resources. The effects of different sintering temperatures and heating time on microstructural features, interface, and properties of the composites were investigated. The structural and microstructural analyses were performed by EPMA, FE-SEM, and EDS. The XRD patterns taken from the cross-section of the prepared composites revealed the composites are composed of TiCx and hexagonal close-packed (HCP) α-Ti. Homogeneous rod-like TiCx particles reinforced TMCs were evaluated by tensile property. The tensile properties of the rod-like TiCx-reinforced TMC show that the tensile strength (UTS) is 479 Mpa, which is 81.4% higher than pure titanium. The formation mechanism and enhancement mechanism of rod-like TiCx particles are also discussed.
RESUMEN
The conventional manufacturing process of fiber-reinforced metal matrix composites via liquid infiltration processes, preform manufacturing using inorganic binders is essential. However, the procedure involves binder sintering, which requires high energy and long operating times. A new fabrication process without preform manufacturing is proposed to fabricate short carbon fiber (SCF)-reinforced aluminum matrix composites using a low-pressure infiltration method. To improve the wettability between fiber and matrix, fibers were plated copper using an electroless plating process. The low-pressure infiltration method with preformless succeeded in manufacturing a composite with a volume fraction of about 30% of carbon fibers.The fiber orientation of the composite material manufactured without preform and the fiber orientation of the composite material manufactured using an inorganic binder was almost the same. The manufactured composites with preformless have high hardness and high thermal conductivity.
RESUMEN
Polyvinyl alcohol (PVA)-based carbon nanofiber (CNF) sheets are fabricated as an innovative thermal interface material (TIM), which is a potential substitute for traditional TIMs. Five types of PVA-based CNF sheets were fabricated at different mass ratios of PVA:vapor-grown carbon fiber (VGCF) (1:0.100, 1:0.070, 1:0.050, 1:0.030, 1:0.025). The thickness of the PVA-based CNF sheets was 30-50 µm, which was controlled by the amount of VGCF. The microstructure of the CNF sheets indicated that VGCFs were arranged in random directions inside the sheet, and PVA was formed as a membrane between two VGCFs. However, many pores were found to exist between the VGCFs. The porosity of the PVA-based CNF sheets decreased from 25 to 13% upon decreasing the mass ratio of VGCF from 43.38 to 16.13%. The density and Shore hardness of all CNF sheets were 1.03-1.15 × 106 g m-3 and 82.4-85.0 HS, respectively. The highest thermal conductivity, measured as the mass ratio of PVA:VGCF, was achieved at 1:0.05, with the in-plane thermal conductivity of the fabricated sheet being 14.3 W m-1 k-1.
