The Materials Science Division (MSD) of CSIR - National Aerospace Laboratories has been carrying out R&D on NiTi Shape Memory alloys (SMAs) since 2002. The Division has successfully developed the know-how for the processing of NiTi SMAs in various semi-finished and finished product forms. The SMAs developed are suitable for both engineering and biomedical applications. The technology has been transferred to Mishra Dhatu Nigam (MIDHANI) Limited, Hyderabad, a Defence Public Sector Undertaking (DPSU), in the year 2017, for commercial production and marketing. Currently, collaborative research is underway with the leading medical institutes of the country for design and development of stents for biomedical applications.
Shape Memory Effect and Superelasticity
Nickel-titanium (NiTi) SMAs have received considerable scientific attention because of their two unique functional properties: shape memory effect (SME) and superelasticity (SE). SME is the ability of the material to be deformed at low temperature and then revert to its original shape upon heating above a critical temperature. SE is the ability of the material to experience large recoverable strains when deformed within a temperature range. These, combined with the superior mechanical properties and corrosion resistance make SMAs as promising class of material for a variety of engineering and biomedical applications.
The laboratory is equipped with state-of-the-art processing facilities for undertaking R&D work on NiTi SMAs. The facilities include vacuum arc melting furnace, hot and cold rolling mills for wires and strips, wire drawing machine, heat treatment furnaces (controlled atmosphere and vacuum), special furnaces for shape memory heat treatment, set-up for stabilization of wire properties for repetitive strain applications.
The SMA laboratory has the characterization facilities for evaluation of functional and mechanical properties of NiTi SMAs under application environment. The facilities include differential scanning calorimeter (DSC), universal tensile testing machine (UTM), rotating beam fatigue testing machine for wires, thermo-mechanical fatigue testing machine,
Modulated Differential Scanning Calorimetry
Study of phase transformation
Make: TA Instruments
Temperature Range: -180 to 500°C
Temperature accuracy: ± 0.1°C
Sensitivity: 0.2 µW
Baseline reproducibility: ±10 µW
Universal Tensile Testing Machine
Evaluation of tensile properties
Electro-mechanical system for tensile testing of thin specimens (wires/strips)
Max. Load: 5 kN
Temperature Range: -100 to 250°C
Control: Fully automated through software
Speed Range: 0.01 to 1000 mm/min
Load accuracy: 0.5% of indicated load
Thermomechanical Fatigue Testing Machine
Evaluation of functional fatigue properties
Custom built apparatus for evaluation of thermo-mechanical fatigue behaviour of NiTi shape memory alloy wires. Conceptualized and designed by CSIR-NAL.
Make: Pragathi Solutions, Bangalore
Rotating Beam Fatigue Testing Machine
Rotating beam fatigue machine can be used for testing of small diameter wire in a simple and rapid method for obtaining fatigue strength and endurance limit values to serve as quality indexes.
Make: Valley Instruments, USA
Suitable for mechanical fatigue testing of thin wires with diameter as low as 100 µm
NiTi SMA Products
The laboratory has also developed expertise for shape setting as well as surface preparation of the products depending on the nature of the applications.
Engineering Products (technology transferred to MIDHANI, Hyderabad)
Biomedical Products (under development)
Specially designed NiTi SMA stents are being developed in collaboration with Biomedical Technology Wing of Sree Chitra Tirunal of Medical Sciences and Technology, Trivandrum and Dr. Cherian Heart Foundation, Frontier Lifeline Hospital, Chennai.
Pulmonary valve stent NiTi-ring for aortic stent-graft
Last updated on : 16-08-2018 02:47:21pm