Hot press sintering effects and wear resistance of the Al-B4C composite coatings of an AA-2024 alloy

In this study, the surface of AA-2024 alloy substrate was coated with an Al-B4C reinforced composite using hot press sintering. Al and B4C powders were synthesized by mechanical alloying. To this end, four samples were prepared. As a reference sample, AA-2024 substrate was coated with pure Al powder under 110 MPa pressure. In the other samples, the AA-2024 substrate was coated with metal matrix composites (MMCs) contained in Al-5 wt.-% B4C at 90, 110 and 130 MPa. The microstructure of the transition zone formed between the AA-2024 substrate and the coating layer of the coated samples, the microstructure of the Al/B4C MMCs coating, the macro hardness, the linear reciprocating and forth wear resistance of the coating layer were investigated. In addition, an optical microscope (OM), scanning electro microscope (SEM) images and EDS analysis of the microstructure were used. It was observed that the B4C powders were homogeneously distributed in the Al matrix in the microstructure of the coating layer. It was also found that the gaps between the grains in the microstructure of the coating layer and their size decreased with an increase in pressing pressure. Accordingly, it was concluded that macro hardness increased and weight loss decreased.

EFFECT OF PRECIPITATION HARDENING ON CORROSION BEHAVIOR FOR ALUMINUM ALLOYS 2024 AND 6061 IN 0.5M HCL

The corrosion behavior of both AA 2024 and AA 6061 aluminum alloys in 0.5M HCl before and after solution treatment at room temperature (25 oC) was investigated in this paper to know the effect of the solution heat treatment on the corrᴏsion behavior of both 2024 and 606 aluminum alloys. Using the cyclic polarization test, the corrosion resistance of AA 2024 aircraft aluminum alloy decreases after solution treatment at 495 oC for 2hr from (9.490×10-3 mm/y) to (1.309×10-3 mm/y), while the corrosion resistance of AA6061 aircraft aluminum alloy decreases after solution treatment at 530 oC for 2hr from (886.3× 10-3 mm/y) to (1.270×10-3 mm/y). Pitting corrosion was the prevalent type of corrosion for both alloys.

Cerium Stearate Electrodeposited Superhydrophobic Coatings for Active Corrosion Protection of Anodized AA 2024-T3

The present study investigated the active corrosion protection provided by superhydrophobic cerium stearate coatings. Superhydrophobic cerium stearate was deposited on anodized AA 2024-T3 at 40 V with different electrodeposition times using a simple DC electrodeposition technique to know the role of electrodeposition time on surface morphology, hydrophobicity, and corrosion resistance. We characterized the structure and morphology of cerium stearate to understand its formation mechanism. Electrodeposition process at 40 V for 120 min resulted in the formation of dual scale Allium giganteum like micro/nano hierarchical texture of cerium stearate with a water contact angle (WCA) of 165 ± 1.6°. The cerium stearate coating obtained for 120 min process time had excellent self-cleaning property and good chemical stability, environmental stability, and mechanical durability acceptable for industrial applications. Electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET) were used to investigate the active corrosion protection of cerium stearate coating. The electrodeposited cerium stearate coating showed active corrosion protection based on self-healing ability by releasing cerium (Ce3+) ions.

Deformation and Anchoring of AA 2024-T3 rivets within thin printed circuit boards

This work evaluates the viability of applying Friction Riveting as an alternative for the assembly of components on printed circuit boards (PCBs). The popular press-fit technology for assembling components on PCBs consists of a pin inserted tightly into a relatively smaller hole, resulting in good electrical and mechanical properties. However, some limitations are highlighted, such as numerous processing steps and the need for predrilled holes. Friction Riveting is based on mechanical fastening and friction welding principles, where polymeric components are joined with metallic rivets through frictional heating and pressure. The main benefits of using Friction Riveting in PCBs compared with fit-press are (i) a reduced number of processing steps and (ii) shorter joining cycles, because there is no pre-drilling involved with fasteners anchored within the PCB in a single step. The joints were manufactured using 5 mm diameter AA-2024-T3 rivets and 1.5 mm thick glass-fiber-reinforced epoxy laminates (FR4-PCB). It is shown for the first time that it is possible to deform metallic rivets within thin composite plates at a reduced diameterto-thickness ratio. The feasibility study followed a one-factor-a-time approach for parameter screening and optical microscopy assessed joint formation of the deformed rivets inside the laminates through volumetric ratio (VR). The joints present significant deformation (VR=0.5) at the tip of the rivet inserted into overlapped PCBs plates, with thicknesses below 3.0 mm, which is considered the lowest achieved so far with Friction Riveting.

structural characterization and dielectric properties of the effect of carbon nanotubes and silicon on AA2024 Metal Matrix Composites

This research work focuses on the formation of AA2024-carbon nanotubes-silicon hybrid metal matrix composites. Structure morphology, structural characterization, elemental identification and dielectric properties of AA 2024 in the presence of carbon nanotubes, silicon and its combinations at various proportions were evaluated using SEM, XRD, EDX and Hioki 3532-50 LCR Hi-Tester. A two-stage stir casting method was used for the fabrication of AA2024 hybrid metal matrix composites. It was observed that the size of the AA 2024 + 4% CNT + 2% Si composite was found to be 23.6 nm, this shows enhanced results than other composites prepared. Dielectric properties of composites were characterized as a function of composition and frequency. It was found that the dielectric constant, dielectric loss and dissipation factor decreases smoothly with an increase of reinforcements and also frequency.