The Effect of Pulsed Power During Electrochemical Surface Modification on the Wettability of Aluminum and Titanium Alloy

Abstract

Abstract Aluminum and especially titanium alloy are increasingly being used to replace traditional metals in many new applications due to their high strength-to-weight ratio and biocompatibility. Surgical implants need to have a hydrophilic nature when tissue growth is desired, while they need to be hydrophobic if tissue/microbial growth is not expected. Thus, there is a need to control the wettability of these metals. This study used a sodium chlorate electrolyte to control the wettability of 1-inch by 3-inch aluminum and titanium alloy samples using an electrochemical surface modification (ECSM) process. Duty cycle, frequency, and ECSM duration were modified while voltage was held constant at 10 V. Duty cycles of 25%, 50%, 75%, and 100% (or direct current) and frequencies of 1 kHz and 100 kHz were used. The time of processing was changed to allow the samples to have an equal active time with 2000, 1000, 667, and 500 seconds for 25%, 50%, 75%, and 100% duty cycles, respectively. A first principles-based theoretical model was developed in this study to predict the pulse power setting needed to achieve the desired wettability in the samples by measuring the sample mass before and after ECSM. The model was validated with experimental results. The surface’s wettability switched from superhydrophilic to hydrophilic after the sample was heated in a furnace. Both the metals showed a change in contact angle behavior after evaporation of the residual water. This study allows for the use of ECSM as a technique to modify the surface of implants with controlled wettability for improved osseointegration.