INVESTIGATION OF THE EFFECT OF SINTERING TEMPERATURES ON THE PRODUCTION OF POROUS NITI ALLOY BY LOOSEN SINTERING METHOD

Abstract

This article aims to produce NiTi shape memory alloys, which show superelasticity and shape memory effect, as well as good biocompatibility and corrosion properties, in open and porous sizes ranging from 100-500 μm, which are required for use as implants. This structure of pores is necessary to allow tissue growth and fluid flow inside the implants. Many powder metallurgy methods have been used in producing porous NiTi shape memory alloys. However, the packaging pressure used in these methods has not successfully created the desired pore distribution, shape, and size. The methods by which it can be produced are costly in terms of cost. In the study, production was carried out by sintering the powder mixture poured into molds without pressure with the help of binder polymers. This sintering process was carried out in an argon atmosphere for 1 hour at temperatures 1050, 1125, and 1200 °C. The study shows that pressureless loosen sintering can produce porous NiTi alloys, which is the more straightforward method. The pore distribution and proportions were examined. Homogeneous distribution and pores in desired sizes are created. It has also been determined that the binder polymer has a space-retaining effect. It was determined at which temperature the alloy sintered at different temperatures contained the desired B2 austenite phase for superelasticity. Austenite start and finish temperatures were determined for the alloy produced at each sintering temperature. As a result of this research, it was determined which phase was denser at which temperature, and the phase transformation temperatures were found. The exact temperature measurements can be calculated by changing the sintering time parameter. In addition, the change in phase transformation temperatures can be measured by heat treatment after sintering. Porous NiTi alloys can be used as dental and medical implants thanks to their excellent biocompatibility and corrosion resistance. This method will decrease production costs, and more people will have access to this material. In general, the mechanism of sintering methods is joining the points in contact with the packaging pressure by necking. In this study, the combination of the grains with the polymer without packaging pressure with the thermal expansion mechanism reveals the originality of the study.