Page 23 - PR 2014 2016 10 Materials and Nanotechnology

Materials and Nanotechnology | Progress Report 299

Dental implants are a class in itself due to its
size, chemical and biological environment. This
paper presents a study on the electric signals
from a strain gage used in a custom-made lab-
oratory micro torque meter specially developed
to evaluate the influence of the bone-implant
and implant-abutment screwed interfaces on
the micro torque signals. The original electric
signals were acquired via National Instru-
ments (NI) hardware and real time processed
with the Labview® software for the evaluation
of noise and its relation to the physical values
of interest and equipment precision (Figure 29).
The results indicate the need of careful atten-
tion to the noise pickup, noise source controls
and mechanical amplification of the original
signal in order to obtain higher accuracy of
the equipment and automated control on the
equipment (Figure 30).

limits leading to a reduction of some mechan-
ical properties. In this study, Grade 91 tubular
joints were made through welding by using
the GTAW process at the root and the SMAW
process in the subsequent welding layers. The
welded joints were subjected to PWHT with
different tempering times (1h, 4h e 8h) and
their mechanical properties were evaluated by
performing conventional tensile, elevated-tem-
perature tensile (540°C), Charpy V-notch im-
pact toughness, Vickers hardness testing and Figure 29: Image showing the inner and main parts of a prototype
micro torquemeter.
microstructural characterization (Figure 28).
Results indicated that mechanical properties of
Grade 91 steel change with increasing temper-
ing time, and a better combination of strength
and toughness can be reached with more than
4 hours of PWHT, under certain conditions.

Study of the strain gage signals for the
control of a micro torque meter

The controls of the stresses on the bone-im-
plant and implant-abutment interfaces are
Figure 30: Experimental torque against microstrain calibration
crucial for the performance of an implant. curve for the torquemeter.