Manufacturing of Aluminum Nano-Composites Reinforced with Nano-Copper and High Graphene Ratios Using Hot Pressing Technique

In this study, the nano-aluminum powder was reinforced with a hybrid of copper and graphene nanoplatelets (GNPs). The ratios of GNPs were 0 wt%, 0.4 wt%, 0.6 wt%, 1.2 wt% and 1.8 wt%. To avoid the reaction between aluminum and graphene and, consequently, the formation of aluminum carbide, the GNP was first metalized with 5 wt% Ag and then coated with the predetermined 15 wt% Cu by the electroless coating process. In addition, the coating process was performed to improve the poor wettability between metal and ceramic. The Al/(GNPs-Ag)Cu nanocomposites with a high relative density of 99.9% were successfully prepared by the powder hot-pressing techniques. The effects of (GNPs/Ag) and Cu on the microstructure, density, hardness, and compressive strength of the Al-Cu nanocomposite were studied. As a result of agitating the GNPs during the cleaning and silver and Cu-plating, a homogeneous distribution was achieved. Some layers formed nano-tubes. The Al4C3 phase was not detected due to coating GNPs with Cu. The Cu9Al4 intermetallic was formed during the sintering process. The homogeneous dispersion of Cu and different ratios of GNs, good adhesion, and the formation of the new Cu9Al4 intermetallic improved in hardness. The pure aluminum sample recorded 216.2 HV, whereas Al/Cu reinforced with 1.8 GNs recorded 328.42 HV with a 51.9% increment. The compressive stress of graphene samples was improved upon increasing the GNPs contents. The Al-Cu/1.8 GNs sample recorded 266.99 MPa

Direct Observation of Induced Graphene and SiC Strengthening in Al–Ni Alloy via the Hot Pressing Technique

In this study, Al/5 Ni/0.2 GNPs/x SiC (x = 5, 10, 15, and 20 wt%) nanocomposites were constituted using the powder metallurgy–hot pressing technique. The SiC particles and GNPs were coated with 3 wt% Ag using the electroless deposition technique then mixed with an Al matrix and 5% Ni using ball milling. The investigated powders were hot-pressed at 550 °C and 600 °C and 800 Mpa. The produced samples were evaluated by studying their densification, microstructure, phase, chemical composition, hardness, compressive strength, wear resistance, and thermal expansion. A new intermetallic compound formed between Al and Ni, which is aluminum nickel (Al3Ni). Graphene reacted with the Ni and formed the nickel carbide Ni3C. Additionally, it reacted with the SiC and formed the nickel–silicon composite Ni31Si12 at different percentages. A proper distribution for Ni, GNs, and SiC particles and excellent adhesion were observed. No grain boundaries between the Al matrix particles were discovered. Slight increases in the density values and quite high convergence were revealed. The addition of 0.2 wt% GNs to Al-5Ni increased the hardness value by 47.38% and, by adding SiC-Ag to the Al-5Ni-0.2GNs, the hardness increased gradually. The 20 wt% sample recorded 121.6 HV with a 56.29% increment. The 15 wt% SiC sample recorded the highest compressive strength, and the 20 wt% SiC sample recorded the lowest thermal expansion at the different temperatures. The five Al-Ni-Gr-SiC samples were tested as an electrode for electro-analysis processes. A zinc oxide thin film was successfully prepared by electrodeposition onto samples using a zinc nitrate aqueous solution at 25 °C. The electrodeposition was performed using the linear sweep voltammetric and potentiostatic technique. The effect of the substrate type on the deposition current was fully studied. Additionally, the ohmic resistance polarization values were recorded for the tested samples in a zinc nitrate medium. The results show that the sample containing the Al-5 Ni-0.2 GNs-10% SiC composite is the most acceptable sample for these purposes