Experimental research
2021 - Present
High Temperature Ceramics
Characterizing mechanical, thermal, and failure properties of advanced ceramics for solar energy applications
(a) SEM characterization of ceramics using Binder-Jetting, an Additive Manufacturing method. (b) Fabrication of complex ceramic parts and structures. (c) Schematic of Concentrated Solar Energy plant
Advanced ceramics
To meet the goal of advancing solar receivers and heat exchangers and meeting the next-generation requirements, ceramics are proposed as the choice of materials. At the high-temperature operating conditions (of ~ 800 C) for long durations, they can show better creep-rupture resistance compared to stainless steel and nickel-based metal alloys (such as 740 H) as per the lifetime estimation using srlife. Hence, characterizing their mechanical, thermal, and failure properties to establish their reliability for the application as a structural component is essential. In the current research, the characterization of commercial grade silicon-carbide, additively manufactured reaction bonded silicon-carbide, and MAX Phase ceramics is being conducted.
More information on the current research is available in the Publications Section.
2016 - 2021
Lab introduction
The video introduces the Extreme Environment Materials Lab which is a part of the Department of Aerospace Engineering at Texas A & M University. The PI of the lab is Dr. Jean-Briac le Graverend.
The video also describes the experimental setup and its capabilities with regard to stress and temperature. Lastly, the video talks about the materials tested and characterized which include Ni-based super alloys and High-Temperature Shape Memory Alloys (HTSMAs).
Thermomechanical Tests
The video demonstrates two types of thermomechanical tests performed on HTSMAs apart from isothermal creep. The first is a Uniaxial Constant Force Thermal Cycling (UCFTC) and the second is an Alternating Isothermal Creep + UCFTC.
Post Experimental Analyses
The video demonstrates two types of ex-situ post-experimental analyses carried out by our lab on HTSMAs subsequent to testing. The first is Differential Scanning Calorimetry (DSC) and the second is X-ray diffraction analysis which is carried out at an external facility.
High Temperature Shape Memory Alloys
Investigating the coupling between phase transformation and viscoplasticity in polycrystal HTSMAs
Strain-time responses generated on conducting UCFTC tests at 1, 10 & 50 C/min thermal cycling rates, by cycling between 100 & 500 C at 500 MPa
The high temperature behavior of a Ti-rich Ni-Ti-20Hf HTSMA was investigated through thermomechanical tests involving isobaric conditions and thermal cycling at different rates. The thermomechanical conditions were chosen to activate transformation and viscoplasticity, in order to observe a coupling between the phenomena.
The entire macroscopic response of the HTSMA is observed to be rate-dependent. The response changes drastically on increasing the rate from 1 to 10 C/min, but remains fairly the same in terms of magnitudes and trends from 10 to 50 C/min. Hence the thermal cycling rate is an important factor to consider during UCFTC testing and training of these alloys.
The thermal cycling rate basically controls the activation of viscoplasticity and TRIP, and the accumulation of retained martensite, all of which affect phase transformation. Viscoplasticity has a major effect at slow rates (of 1 C/min), but its effects get overshadowed by TRIP at fast rates (of 10 & 50 C/min). While the effect of retained martensite is seen at all three rates.
More results and conclusions from the project are available in Publications Section.