Page 305 - 00. Complete Version - Progress Report IPEN 2014-2016

Materials and Nanotechnology | Progress Report 305

constant load mode at 250 and 319 MPa. The terization of the nitride layer was performed
techniques used in this study were optical with the aid of optical microscopy (OM) and
microscopy and scanning electron microsco- X-ray diffraction (XRD). Tensile tests were per-
py. Fractographic analysis of the creep test- formed between 600 and 1000°C and defor-
ed samples showed necking and microcavi- mation rates between 0.0002 and 0.002 s−1.
ties. The creep results revealed a significant The results have shown that nitrided sample
increase in material strength. present expanded fcc phase and chromium ni-
tride (CrN) phases. Tensile tests showed that
Aiming at applications such as biomaterial, there was no significant difference in the yield
the effect of plasma nitriding on the Ti-6Al-4V strength and elongation between non-nitrid-
alloy in fatigue behavior has be studied. The ed and plasma-nitrided samples at the same
studies are being performed in the Ti-6Al-4V temperatures. Serrated stress–strain behavior
alloy will be comparative in the alloy with and was observed in the curves obtained at 600 and
without nitriding. 700°C, which was associated with the dynam-
ic strain aging effect. At 600°C, the increase in
Ti-Al intermetallic alloyss with an Al content strain rate promoted an increase of the ampli-
between 35 and 65 (atomic%) are usually di- tude and oscillation frequency of the stress.
vided into two categories: single-phase or two-
phase alloys. The first group consists exclu- Evaluation of adaptation and removal
sively of the ο-TiAl phase, and the second, by resistance of impacted abutment in
the union of the ο-TiAl and ο2-Ti3Al phases. small diameter conical dental implant
Single-phase alloys do not have a balanced
set of properties. The dual phase alloys allow Dental implants of alloy Ti6Al4V (grade V)
the desired characteristics to be systematized of narrow diameter came to solve a constant
by means of different microstructures, which situation in the current implantology, which
can be classified into several groups: (a) par- would be the installation of implants in re-
tially lamellar, (b) near-ο, (c) duplex and D) duced mesiodistal spaces, mainly to allow a
completely lamellar. The study has focused on final prosthesis with appropriate aesthetic re-
the microstructural characterization of Ti-Al- quirement. Because it is a 2-part system, the in-
type alloys (Ti-44Al-4Nb-1Mo-B and Ti-48Al- stallation of the abutment, made in the same
2Cr-2Nb-B). alloy, is performed by impaction because its
stabilization through a screw becomes incon-
Nickel based superalloys sistent due to difficulties in machining such

tiny components. The abutment after impac-
Inconel is a nickel-chromium-molybdenum tion in various ways in the implants were sec-
superalloy with high corrosion resistance and tioned at 2 mm from the implant platform and
strength at elevated temperatures. Surface the two halves were observed in a scanning
modification of Inconel 625 has been carried electron microscope (SEM)(Figure 27), in or-
out to improve mechanical properties at el- der to measure the gap or the space between
evated temperatures. Creep and hot tensile the implant/ abutment. Similarly, after the
tests were performed to evaluate the mechan- abutments were impacted in the implants,
ical properties at elevated temperatures. The they were subjected to tensile test to evaluate
surface modification that was carried out was their required removal force. This study aimed
plasma nitriding. The microstructural charac- to evaluate the accuracy, the juxtaposition of