Dataset for "Effects of copper cementation on aluminum chips used for recycling in a friction-induced recycling process"

Aluminum chips (EN AW-6060, LxWxH 1.99 ± 0.08 x 1.6 ± 0.07 x 0.1 ± 0.01 mm) were immersed in 0.05 M CuSO4 solution for either 10, 30, 50, or 1020 min. Sample preparation Cleaning. The Al chips were cleaned using a JEL RRM Mini-II roe wheel mixer. To this end, they were filled in a suitable flask, and three times their weight in IPA (p.A.) was added. They were then washed for 10 minutes at a speed of 20 rpm, after which the solvent was exchanged for a fresh one, and the procedure was repeated. Cementation and drying. The cementation solution was a 0.05 M CuSO4 solution (pH 4.4). To prepare it, 9.3634 g of CuSO4 ∙ 5 H2O (VWR) was dissolved in 750 mL of H2O. 10 mL of this solution was taken for an initial ion-selective electrode (ISE) measurement (Hanna Instruments). The rest was added to 150 g of aluminum chips inside a 1 L bottle suitable for the drum hoop mixer. In total, four different states were created: The chips were immersed for either 10 min, 30 min, 50 min, or 17 h (1020 min). After the respective times had elapsed, another 10 mL of the solution were taken for the final ISE measurement. The coated chips were washed thoroughly with DI water. Excess water was drained via a sieve. To remove the remaining water, the chips were again immersed in IPA and then drained two consecutive times. Remaining IPA was removed in an oven at 140 °C over 45 minutes. The drying process was controlled via weight loss measurements. Characterization Fourier transform infrared (FTIR) spectra of the aluminum chips were recorded through diffuse reflective infrared fourier transformspectroscopy (DRIFTS) with a Bruker Vertex 70 equipped with a Harrick Praying Mantis™ Diffuse Reflection Accessory. IPA-cleaned chips served as reference for all DRIFTS measurements. All spectra were baseline-corrected, and atmospheric water bands were removed. Baseline correction was done in OPUS using a polynomic line shape with 0 iterations and pins at 4000, 3800, 2250, 1900, 1300, and 850 cm‑1. Removal of water bands was done by recording the reference spectrum at two different times. Constant N2 flow in the sample chamber steadily reduced the water content inside it, leading to an absorption spectrum that only depicts the change of said water content. Subtracting this spectrum from a sample spectrum by a factor cancels out the unwanted water bands. Ion selective electrode (ISE) measurements were performed with a Hanna Instruments HI-6000 in combination with the copper selective electrode HI4108. From a starting volume of 750 mL per state, 10 mL samples were taken before the addition of the Al chips and further 10 mL were taken at the end of the reaction. The 10-mL samples were always diluted to 100 mL with H2O, and 2 mL of ionic strength adjuster (ISA) (HI4000-00, Hanna Instruments) were added. Visible-light micrographs of the coated aluminum chips were recorded with a Keyence VHX‑7000 digital microscope. Close-ups of the different chips were stitched together using Affinity (Canva). Particles were measured using ImageJ (ver. 1.54i).[16] More images were taken for lower cementation time in order to roughly have parity regarding the number of particles visible. Element distributions based on energy-dispersive X-ray spectroscopy (EDX) were taken on a ZEISS NEON® 40 scanning electron microscope (SEM) in combination with an Ultra-Dry detector by Thermo Fisher Scientific using an acceleration voltage of 20 kV and a 30 µm aperture. High-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) imaging (providing predominantly qualitative atomic-number contrast) and spectrum imaging analysis based on EDX were performed at 200 kV with a Talos F200X transmission electron microscope equipped with an X-FEG electron source and a Super-X EDX detector system (FEI). Before STEM analysis, the specimen was placed in a high-visibility, low-background holder and subjected to a Model 1020 Plasma Cleaner (Fischione) treatment for 8 s to eliminate potential contamination. TEM specimen preparation was done by in situ lift-out using a Helios 5 CX focused ion beam (FIB) device (Thermo Fisher). To protect the polished cross-section, with its normal parallel to the extrusion direction, a carbon cap layer was deposited beginning with electron-beam-assisted and subsequently followed by Ga-FIB-assisted precursor decomposition. Afterwards, the cross-sectional TEM lamella was prepared using a 30-keV Ga-FIB with adapted currents. Its transfer to a 3-post copper lift-out grid (Omniprobe) was done with an EasyLift EX nanomanipulator (Thermo Fisher). To minimize sidewall damage, Ga ions with only 5-keV energy were used for final thinning of the TEM lamella to electron transparency. Tensile tests were performed on a ZwickRoell universal testing machine Z100 with tensile specimens of form F according to DIN 50125. A strain rate of 0.008 s-1 and a clamping length of 30 mm were used. Hardness tests were performed using a Nexus 4303 hardness tester from INNOVATEST Europe BV, Maastricht. The Vickers method according to DIN EN ISO 6507-1 was used in the low-force range of HV0.3