Enhanced solder wettability (SW) of oxidized-Cu (OC) with 96.5Sn-3Ag-0.5Cu lead-free solder (LFS) by Ar-H 2 plasmas was investigated. The SW of OC was significantly improved from 0% wetting of Cu oxidized in air at 260°C for 1 h to 100% wetting of OC modified by Ar-H 2 plasmas for 10 min. The SW of Cu was found to be highly dependent on the surface characteristics of Cu. By decreasing the total surface energy (TSE), decreasing the polar surface energy (PSE), and increasing the dispersive surface energy (DSE) on the surfaces of OC modified by Ar-H 2 plasmas, the SW with LFS improves. X-ray photoelectron spectroscopy (XPS) indicates that Ar-H 2 plasma treatment is used to remove the copper oxides CuO and Cu 2 O from the OC surfaces. The ratio of the total amount of Cu 2 O to CuO was found to be a good indication of how the copper oxides CuO and Cu 2 O affect the PSE, DSE, and SW of Cu.
This study is aimed to investigate the properties of Ni-rich Ni-Ti shape memory alloy sheet parts during and after deep drawing process at room temperature, in which the metal is under plane tension-compression stress state. After annealing at different elevated temperature, shape memory alloy sheet is formed at room temperature by a circular cylindrical punch in different forming depths. Thereafter the deep drawn sheet part is subjected to aging for shape memory treatment. A free shape recovery test is further conducted onto the deep drawn shape memory alloy sheet part. As a result, the sheet metal has austenitic phase at room temperature, which shows superelasticity. Too small forming amount causes severe springback and the form of the deep drawn sheet part is very hard to detect with the naked eye. Only if a forming amount greater than or equal to 4 mm is applied, a form can be achieved on to the sheet part. The subsequent aging shape memory treatment can induce further springback of the deep drawn sheet part. The higher the temperature of the previous annealing, the less the springback by aging. The free shape recovery test shows that the deep drawn sheet part only undergoing annealing without shape memory treatment still possesses shape memory effect. Nevertheless, the deep drawn sheet part aged for shape memory can show a better shape recovery.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.