The micro-wear technique and its application to ultrathin film systems

Abstract

A micro-wear testing technique has been developed by incorporating a piezoelectric pusher into an existing microindenter system. The pusher and its associated servo-control circuitry were designed to generate a precise reciprocating horizontal motion at the indenter tip for implementing a microscaled wear test. The information acquired from the test includes the wear loading curve, i.e., the normal applied load versus wear penetration depth, the friction force, and in turn, the apparent wear friction coefficient. Measuring the electrical resistance across the coating thickness is also possible if an electrical conducting indenter is utilized. Furthermore, in conjunction with the surface characterization tools, the wear morphology revealed useful information regarding the coating failure mechanism(s) and shed some light toward understanding coating tribology. The tester design concepts, operating procedure, data acquisition, and analysis will be examined. Experimental results on ultrathin carbon coatings with various thicknesses will be employed to illustrate the capabilities of the micro-wear tester.

Miniature piezoelectric actuators: design concept, fabrication and performance evaluation

“…Compared to laminated bimorph types of miniature piezoelectric actuator, devices based on piezoelectric stack actuators are gaining ever more emphasis due to their capabilities to output significantly more force. Piezoelectric stack actuators stacking piezoelectric layers into a stack to reduce the voltage level needed to obtain the same amount of displacement/force use the d 33 mode (Chang and Wang 1988, 1990, Lee and Wu 1993, Wu and Lee 1994a. As piezoelectric stack actuators do not have the geometric effect on their side similar to that of the bimorph type of actuator, methodologies that transform the large-force, small-displacement characteristics of piezoelectric actuators need to be developed further to facilitate the use of these types of actuator.…”

“…Design examples based on this design concept will be examined in detail. Four devices powered by using piezoelectric stack actuators and designed by using a waveguide, the lever principle and resonant effects (Chang and Wang 1988, 1990, Lee and Wu 1993, Wu and Lee 1994a will be presented to illustrate this line of thinking within the NTU MEMS Collective. A newly developed laser Doppler interferometry system specifically designed for piezoelectric micro-actuators is also examined.…”