ORIGINAL ARTICLE Wettability characterization and adhesion enhancement of arc-treated surface of aluminum alloys Mehdi Asgharifar & Fanrong Kong & Joshua Abramovitch & Blair Carlson & Radovan Kovacevic Received: 13 September 2013 /Accepted: 16 December 2013 /Published online: 12 January 2014 # Springer-Verlag London 2014 Abstract The aim of this study is to determine the wettability-enhancing effects of an atmospheric pressure, di- rect current (DC) plasma arc discharge on the surface of aluminum alloys. Wettability is a critical factor in engineering applications such as biomedical implants, painting, and adhe- sive bonding. For example, in the realm of adhesive bonding, greater wettability improves a metal substrate's attraction to an adhesive material and results in a higher bond quality. In this study, the contact angle was determined and compared as a measure of the wettability using two different techniques: the sessile drop and the ballistic deposition with water as a test liquid. The effect of different arc discharge process parameters on the wettability, including arc current and plasma torch velocity, was studied. A two-dimensional finite element anal- ysis based on the volume-of-fluid model was carried out to explore the behavior of droplet (e.g., spreading and stabiliza- tion) on an ideal surface. Additionally, the values of the dynamic receding contact angle were measured through the simulation by applying the tilted plate method and considering the surface roughness to compare the results with the values obtained from the ballistic deposition method. Studying the wettability alteration of the surface of aluminum alloys sub- jected to the arc treatment revealed the wettability reduction over time. Additionally, it was found that there was a linear correlation between the contact angle value and the strength of adhesively bonded joints using two structural adhesives. The results of this study in the wettability modification of alumi- num subjected to the arc treatment and wettability alteration of the treated substrate over time may be used as a quality assurance tool to design the production process and achieve the desired quality and strength in adhesively bonded joints. Keywords Wettability . Contactangle . Arcdischarge . VOF . Adhesively bonded joint . Aluminum alloys Nomenclature A Actual surface area A 0 Nominal surface area b y-Intercept CA Contact angle d Average drop diameter H Reduced hysteresis H w Reduced hysteresis obtained for water H ad Reduced hysteresis obtained for adhesive I Arc current G Fracture energy G 0 The surface energy m Line slope R Wenzel roughness factor R a Arithmetic average of the roughness profile t Time after droplet contact with substrate v Plasma torch velocity V Drop volume W A Work of adhesion W C Work of cohesion θ Contact angle θ 0 Equilibrium Young contact angle θ a Advancing contact angle θ r Receding contact angle This work was partially presented at the ASME 2012 International Manufacturing Science and Engineering Conference (MSEC), University of Notre Dame, June 2012. M. Asgharifar : J. Abramovitch : R. Kovacevic (*) RCAM (Research Center for Advanced Manufacturing), Southern Methodist University, 3101 Dyer St, Dallas, TX 75205, USA e-mail: kovacevi@lyle.smu.edu F. Kong ESAB Welding and Cutting, 411 S Ebenezer Rd, Florence, SC 29501, USA B. Carlson General Motors R&D, 30500 Mound Rd, Warren, MI 48090, USA Int J Adv Manuf Technol (2014) 71:1463–1481 DOI 10.1007/s00170-013-5561-1