INDUSTRIAL APPLICATIONS FOR SHAPE MEMORY ALLOYS

Abstract

Although medical applications for shape memory alloys (SMA) now dominate in today’s market, there are many applications in the industrial sector which have reached large volume production that far surpass the material usage in the medical fields. In the early growth of shape memory alloy technology the most important applications were for fasteners and couplings, mainly in the military sector. With the maturing of the technology, and the broader availability of alloys, industrial applications appear in a wide spectrum of commerce. Eyeglass frames were an early example of a new use of superelasticity which has grown to be a world wide product. Cellular phone antennas consume millions of feet of superelastic wire, and the development of underwire for women’s brassieres, formerly limited to Asian market, is now expanding into a worldwide fashion. A new idea of using superelastic NiTi powder to enforce the resistance of SnPdAg solder against failure induced by thermal stress appears promising. In the automotive sector, European car manufacturers have long been using SMA actuators for transmission fluid control. Now, it is growing with the most recent success in using a NiTiNb plug for sealing high-pressure fuel passages in diesel engine injectors. SMA actuators continue to achieve steady growth in safety valves for both consumer and industrial applications. New actuator applications include a thermal interrupter for protecting lithium ion battery from uncontrollable thermal runaway. Research and development activities continue in vibration and damping principles. Employing either passive or active means are well proven but the commercialization has been slow to develop. Active tuning of resonance frequency and seismic vibration controls may find their niches in the near future. Micro-electromechanical (MEM) devices fabricated using thin film NiTi actuators will also be briefly discussed.