The grant provides support for the acquisition of a nano-indentation system, consisting of a nano-hardness tester (NHT) and an atomic force microscope. Many diverse research groups that are involved in the characterization of materials and in nanomechanical stress analysis will benefit from the acquisition of the NHT. The nano-indentation system will be devoted to the study of micromechanical behavior of MEMS materials on both the micrometer and the nanometer scale. It allows a wide variety of tests, including submicron-sized hardness tests, micro-scratch tests, contact fatigue during cyclic indentation, and constant load creep tests. The instrument will be used in several research projects: (1) the measurement of micromechanical properties of MEMS materials as a function of microfabrication processes and temperature to provide both the micromechanical properties for modeling and the understanding of processing-properties relationships of MEMS microcomponents, (2) the investigation of the contact fatigue of silicon wafers and surface crack initiation associated with cyclic contact between two silicon surfaces or accumulated damage to identify the key variables responsible for contact damage and failure in MEMS devices, and (3) the study of adhesion phenomena between two surfaces of MEMS microcomponents due to interfacial forces, such as capillary, van der Waals, and electrostatic forces to understand the dominant mechanisms controlling the bonding between solid contact surfaces on the microscale. %%% This nano-hardness tester is the first of its kind at the University of Kentucky. It will have a large impact on research dealing with micromechanics of MEMS structure and characterization of MEMS materials and nanomaterials. For example, it is clear that surface and interface stresses play an important role in determining the deformation characteristics of MEMS microcomponents due to the high surface area to volume ratio. The micromechanical properties determined via nanoindentation tests will allow for consideration of surface effects, such as surface stresses. The long-term research goal is to develop an understanding of the material properties (including elasticity, plasticity, adhesion, and fracture) of advanced materials relevant to micro-electromechanical systems.
