Focus Areas
Collaborators and Funders
Short Overview
Micro and Nanomechanics of Advanced Materials/Ceramics
The present century is recognized as a "Materials Century". The profound context of the term "Materials Century" here refers to the design and development/fabrication of smart and sustainable materials with novel microstructures is going to play a decisive role in the progress of the current century. There is a continuous thrust to develop the engineering and functional materials for miniaturized applications to diminish the potential penury of energy, space and money. All these materials have microstructural aspects that span various length scales ranging from several microns or sub-micron-sized grains to a few angstrom-sized unit cells/atoms. The intermediate length scale between these two is nanoscale defects such as dislocations
(in the case of metals and a few ceramics), ferroelectric domains (in piezo/ferroelectric materials) and shear bands in glasses, and thought to have a pronounced influence on the deformation behaviour of all the above materials. It would be interesting to investigate the deformation response of an individual or clusters of these defects and grains to unravel the early stage of plasticity (i.e., micro and nano plasticity) in these materials. On this front, small-scale deformation testing techniques such as micro tension/compression, micro and nanoindentation, and atomic force microscopy (AFM) are quite popular. My main emphasis is on investigating the in-situ deformation behaviour of these materials using the above deformation testing techniques.
I am leading this work with Prof. Eswara Prasad Korimilli, IIT Indore and Dr. Yong Zhu, NC State University along with the other potential collaborators. The video showcases our efforts in this field.
Fracture Mechanics in 2-D Materials
The present development in functional materials and their demand in M/NEMS devices poses an important question; "Do these materials have the potential to solve the great and pressing problems of society?" Of course, with the discovery of graphene in 2004, 2-D materials/heterostructures have attracted significant attention due to their excellent electronic as well as mechanical properties (For ex., elastic modulus, E around 1 TPa and intrinsic strength around (1/10)*E). The important members of this one-atom-thick 2-D family are graphene, MoSe2, WS2, h-BN and silicene. However, the (super)brittle nature of these structures prevails the instantaneous fracture, and so is the crack propagation. This mainly arises due to various defects present/formed during the large-scale synthesis of these materials and interacting with the crack during the fracture process. The present studies via DFT and MD simulations point out an important knowledge gap in probing the stable crack path and its interaction with various topological defects. On this front, it would be interesting to characterize the microstructural features at the crack tip to gain an understanding of defect induced toughening in 2-D materials.
As an emerging researcher, I am exploring the above aspects with Dr. Yong Zhu @ NCSU. Currently, experiments are being planned and experimental device fabrication work is in progress. The research proposal is at the development stage, and I would be happy to extend this research in collaboration with different research groups. Please direct your queries, suggestions or proposal to vskathavate@gmail.com
Defect-based plasticity/multifunctionality
"There's plenty of room @ bottom".....
by Prof. Richard Feynman, A Great Physicist & Nobel Laureate
The above lecture by Prof. Feynman at CALTECH in 1959 is the main motivation behind exploring this research. The next stage after the materials design process is to establish structure-property correlations and tailor the engineering and functional properties. Over the years, numerous efforts have been directed to tune the functional and engineering performance of the materials by altering the microstructural features at different length scales (discussed above). While dislocations and other defects such as grain boundaries, triple junctions, microcracks, holes and atomic vacancies are
viewed as an obstacle to plastic deformation, recent studies have indicated that mechanical and other functional properties in materials can be enhanced by taming a systematic network of these defects imprinted via various defect engineering techniques. This typically includes dislocation induced toughening in ceramics or ferroelectric domain-assisted toughening in piezoceramics, annealing-induced plasticity in metals, pinning the defects in 2-D materials via controlled fragmentation and high stress-strain driven grain boundary experiments in the bicrystal and polycrystalline materials. It would be interesting to harness the power of the above common, yet important defect engineering techniques to maintain the synergy between various properties in advanced materials.
At present, my main focus is centred on ferroelectric domain engineering and dislocation-domain assisted toughening in piezoceramics and multiferroic thin films. On similar lines, I am also understanding the defect interaction and influence on the crack growth characteristics in 2-D materials. A short video provides some insights into our previous efforts.
Corrosion and Electrochemistry @ Interfaces, and Smart Coatings
"Metals are the greatest gift to the human society" (B.S. Murty et al., in the book "High Entropy Alloys", Elsevier, 2014). Despite the development of functional materials in the present century, engineering/structural metals still play an important role. For instance, as a metallurgist, I always believe there is no replacement for steel. However, one of the downsides of these metals is their ability to form stable oxides in their own environment (i.e., the process of corrosion). Corrosion in metals is of great concern to every metallurgist. According to the survey conducted by the National Association for Corrosion Engineers (NACE), the global cost of corrosion is around $75000 billion (i.e., 4% of global gross domestic product (GDP)) including major sectors such as agricultural, automobile and structural materials industries, and services.
The word/thought corrosion itself poses the strategies to monitor it (I am purposefully avoiding the word "prevention" because in any case corrosion is non-preventable but can be monitored). Some of the strategies on this front are; (i) modifying the metal (i.e., alloying) and its surface (i.e., surface pre or post-treatments), (ii) corrosion inhibitors (i.e., barrier coatings) and (iii) cathodic surface (trim down the rate of reaction). Of all these, protective coatings are the promising way to protect the metals from corrosion. My research focuses on the advanced and open problems related to corrosion at the interface of various coatings and advanced crystalline materials with special emphasis on microstructural length scales. This reflects my commitment to employ various electrochemical techniques to understand the process of corrosion and oxide film formation. I am more interested in understanding; how the addition of a small amount of dopants creates the heterogeneous interfaces and different phases in crystalline metals/alloys, and their subsequent micro and nanoscale effects on pitting and passivation behaviour in various aggressive environments. Furthermore, it would be also possible to detect the corrosion process in its early stages using stimuli-responsive smart coatings. I am also exploring the applications of these polymer-based smart coatings in clinical translation and water/oil repellant applications.
Prof. Pravin Deshpande, COE Pune (COEP) and his group have novel electrochemical testing facilities, while I am leading the efforts in the conceptualization and understanding of the key mechanisms that contribute to the corrosion process. Our joint venture has come to fruition and is reflected in the form of publications in several peer-reviewed journals of international repute such as Surface and Coatings Technology, J. Alloys and Comp., Corrosion Reviews and J. Electrochemical Energy Technology. One of the major achievements during recent times is the book "Smart Coatings: Fundamentals, Advances and Applications" with CRC Press.
