SIMÕES, J. B.; http://lattes.cnpq.br/8279861117114431; SIMÕES, Jackson de Brito.
Resumo:
Shape memory alloy (SMA) have functional characteristics of apparent plastic
deformation recovery and change of mechanical properties when subjected to
temperature variations, providing an increasing interest for engineering
applications and a new way of designing mechanical systems. In this context, it
is important develop new methods to manufacture of mechanical components
mainly of Ni-Ti SMA system. In addition, from end of the 20th century
investment casting has become an effective alternative to forming components
of titanium and its alloys for high-tech applications. However, there is no
information on the use of this process for the manufacture of Ni-Ti SMA
mechanical components. Thus, the aim of this thesis was to evaluate two
investment casting technologies, based on melting and injection of liquid metal
into a mold to obtain miniaturized Ni-Ti SMA components with functional
properties. For this purpose, optimization of controllable process parameters
was performed, followed by thermal and mechanical characterization of Ni-Ti
SMA with shape memory effect and superelasticity properties. Subsequently, in
order to validate the used investment casting processes were made different
shapes of Ni-Ti SMA mini-actuators (Belleville springs, orthopedic clamps,
meshes, cellular structures, springs and bolts), which were submitted to thermal
and mechanical characterization, and non-destructive testing of integrity. Based
on the results, it was concluded that the investment casting processes (Plasma
Skull Push-Pull and Induction Melting with Centrifugal Casting employed were
suitable for manufacture of Ni-Ti SMA mini-actuators with good functional
properties and simple and complex geometries.