Improving corrosion performance by surface patterning

In this research, the effect of surface patterning on the corrosion behaviour of a metal (nickel) was investigated. The idea originates from the fact that hydrophobic (low or non wettable) surfaces can decrease the contact area between a corrosive solution and a surface. In the current work, special surface patterns were created on pure nickel sheets. The corrosion behaviour of those surfaces was studied using a dynamic polarization method in 0.5M H2SO4. It was found that there is a trend or dependency between the hole size (D), the hole distance (L), and the corrosion current density (lcorr). The higher the (D/L)2 ratio, the higher the corrosion current density (lcorr). The corrosion potential (Ecorr) of all samples was lower than that of the reference sample in all the tests. SEM images showed that after the first corrosion test some local corroded regions were created on the surfaces but in the samples with the lowest lcorr there was a slight change in the surface

Micro Motion Amplifiers for Compact Out-of-Plane Actuation

Small-scale, out-of-plane actuators can enable tactile interfaces; however, achieving sufficient actuator force and displacement can require larger actuators. In this work, 2-mm2 out-of-plane microactuators were created, and were demonstrated to output up to 6.3 µm of displacement and 16 mN of blocking force at 170 V. The actuators converted in-plane force and displacement from a piezoelectric extensional actuator into out-of-plane force and displacement using robust, microelectromechanical systems (MEMS)-enabled, half-scissor amplifiers. The microscissors employed two layers of lithographically patterned SU-8 epoxy microstructures, laminated with a thin film of structural polyimide and adhesive to form compact flexural hinges that enabled the actuators’ small area. The self-aligned manufacture minimized assembly error and fabrication complexity. The scissor design dominated the actuators’ performance, and the effects of varying scissor angle, flexure thickness, and adhesive type were characterized to optimize the actuators' output. Reducing the microscissor angle yielded the highest actuator performance, as it maximized the amplification of the half-scissor's displacement and minimized scissor deformation under externally applied loads. The actuators' simultaneously large displacements and blocking forces for their size were quantified by a high displacement-blocking force product per unit area of up to 50 mN·µm/mm². For a linear force–displacement relationship, this corresponds to a work done per unit area of 25 mN·µm/mm². Keywords: microactuators; tactile actuators; piezoelectric actuators; scissor mechanism; motion amplifier; out-of-plane actuato