Advanced Materials Characterisation Techniques

Transcription

1 TEQIP Workshop on Advanced Materials Characterisation Techniques 1-2 nd November, 2014 Department of Materials Science and Metallurgical Engineering IIT Hyderabad About the workshop Materials characterisation is an integral part for understanding the structure- property relationships and suitable material applications. With development in science and technology, characterisation techniques have evolved and facilitated understanding of matter and advanced applications. Characterisation tools and techniques are now available to assess structural as well as functional properties of a material. While the characterisation is a major field for materials scientists, it remains an important aspect for all engineering areas and sciences. In-spite of being a multidisciplinary pursuit, understanding and interpreting data from characterisation techniques can be difficult and misleading. Given this, it is important to know about the characterisation techniques and their developments and at the same time use the obtained results carefully for right conclusions. Schedule of the workshop Day 1 8:30 A.M. 9:15 A.M. Breakfast 9:15 A.M. 9:20 A.M. Lighting of lamp 9:20 A.M. 9:30 A.M. Welcome address 9:30 A.M 11:00 A.M. Keynote lecture by Prof. K Bhanu Shankara Rao (Government of India, Ministry of Steel Chair Professor, MGIT, Hyderabad) 11:00 A.M. 11:15 A.M. Tea Break 11:15 A.M. 12:30 Noon Lecture #1 by Dr. Mudrika Khandelwal (Rheology) 12:30 Noon 1:45 P.M. Lecture #2 by Dr. Shubradeep Chatterjee (X-ray Diffraction) 1:45 P.M. 2:30 P.M. Lunch 2:30 P.M. 4:00 P.M. Lecture #3 by Dr. Suhash Ranjan Dey (Electron Microscopy) 4:00 P.M. 4:15 P.M. Tea Break 4:15 P.M. 5:30 P.M. Lecture #4 by Dr. Pinaki Prasad Bhattacharjee (Electron backscattered diffraction) 5:30 P.M. 6:30 P.M. Discussion 7:00 P.M. 8:30 P.M. Dinner Day 2 9:00 A.M. 10:00 A.M. Breakfast 10:00 A.M. 11:15 A.M. Lecture #5 by Dr. Ranjith Ramadurai (Photoelectron spectroscopy) 11:15 A.M. 11:30 A.M. Tea Break 11:30 A.M. 12:45 P.M. Lecture #6 by Dr. Atul Suresh Deshpande (Surface Area and Analysis) 12:45 P.M. 1:45 P.M. Lecture #7 by Dr. Bharat Bhooshan Panigrahi (Dilatometer: Thermal Expansion Measurement of Solids and Monitoring of Powder Sintering) 1:45 P.M. 2:30 P.M. Lunch 2:30 P.M. 2:45 P.M. Vote of Thanks, Certificate distribution and Closing Remarks 2:45 P.M. 5:30 P.M. Lab Visit (Hostel Lab. and Kandi Lab.)

2 Briefs about lectures The workshop was declared open by Dr. Pinaki P. Bhattacharjee, HOD, department of materials science and metallurgical engineering. He addressed the participants followed by introduction to the keynote speaker. The keynote speaker was Prof. K. Bhanu Shankara Rao. Profile: Ministry of Steel, Govt. of India, Chair Professor, at MGIT Hyderabad. Keynote address Prof. Bhanu Shankara Rao gave a brief introduction to his career followed by presentation on his research focussed on evolution of microstructure during fatigue deformation and fracture. He discussed in details his findings on creep fatigue. He talked about how temperature time effect and several related phenomena can interact synergistically and lead to premature failure. Serrated yield in plastic portion of hysteresis loop is symbol of dynamic strain ageing. He discussed the phenomena in several materials including composite materials for aerospace. He took us through his work which tempted US to offer him American citizenship, which he denied as he wanted to come back to India. He emphasised the importance of characterisation in order to gain mechanistic understanding of material. The deformation and damage has to be characterised by microscope and combined with macroscopic observations. He also demonstrated various forms of fatigue experiments (introduction of waveforms, hold time test, dwell time test). The concept of dynamic straining was introduced, along with microscopic characterisation of the same. The keynote speaker was presented a memento of gratitude and appreciation.

3 Abstracts of lectures by MSME faculty members Dr.Mudrika Khandelwal Rheology Study of flow in matter The lecture covered the science of flow in materials. It was shown that viscosity alone is not enough to define flow of materials. Rheology involves complete characterisation including viscosity, elastic modulus and viscous modulus. Newtonian and non-newtonian fluids were discussed. The importance of time and shear rate in rheological behaviour were discussed. Everyday products were discussed with respect to their rheological behaviour. Objective of the lecture was to answer four questions 1. Why does ketchup not come out easily? 2. How can somebody walk on mixture corn starch and water? 3. Why is it easier to shape clay with slower shear force? And 4. Importance of rheology in chocolates. Dr. Subhradeep Chatterjee X-ray diffraction X-ray diffraction (XRD) is an invaluable tool for the materials characterization. This talk gives an overview of the technique and the outlines the diverse range of questions about a material that can be answered with its effective use. It starts with an explanation of the basic physics of X-ray generation. It then shows how that knowledge can be utilised to understand the concept of filtering the radiation which can avoid many errors of interpretation of the results. Generation of XRD intensity profiles, which serve as fingerprints for materials, is then discussed in terms of the crystal structures of materials. Basics features of the most commonly used XRD instrument, the diffractometer, is explained. Detailed tips are provided on how to interpret the results correctly and how common errors of identification can be avoided. The talk also shows how to extract quantitative information like composition and volume fraction of phases, precise lattice parameters and grain size using XRD. Finally, cutting edge applications of XRD using synchotron sources on in-situ experiments is also highlighted. Dr. Suhash R. Dey Electron Microscopy Human eyes can differentiate two objects only when separated by more than 0.2 mm. For smaller distance distinction, humans require aid in form of microscopes. The talk gave introduction to primitive microscope (optical based), its properties (optics) and limitations (in

4 terms of poor resolution, brightness of the source, etc) and then taken to the needs of higher end microscopy (electron based). For electron microscopy, fundamental of electron-matter interactions and generation of various rays are explained. This is followed by complete utilization of scanning electron microscopy (SEM): starting from sample preparation, electron gun types, SEM scanning methods in terms of raster; signals generations and their capturing in terms of energy and placements with various examples (secondary electron imaging, backscatter electron imaging and diffraction, channeling contrast imaging, elemental analysis mapping through energy dispersive spectroscopy and wavelength dispersive spectroscopy, electron beam induced current). The talk finally ended with three case studies performed by author in his postdoctoral works. Dr Pinaki P. Bhattacharjee Materials Characterization by Electron Backscatter Diffraction Electron Back Scatter Diffraction (EBSD) is a very versatile and powerful technique for characterization of microstructure and texture simultaneously in a wide range of materials. The lecture introduced the basic concepts of microstructural elements and orientation. The fundamental principles of EBSD analysis including formation of kikuchi bands, Hough transformation of kikuchi bands, indexing of the bands and orientation determination were discussed. The usefulness of EBSD analysis in understanding microstructure and texture was illustrated using two case studies, namely, a two phase duplex steel and highly oriented nickel substrates for coated superconductors. Dr. Bharat B. Panigrahi Dilatometer: Thermal Expansion Measurement of Solids and Monitoring of Powder Sintering Dilatometer characterizes the dimensional changes such as volumetric changes or linear changes, as a function of processing temperature and time, on the solid material, including metals, ceramics, polymers and glasses, etc. Normally two different types of dilatometer are available, one is push-rod

5 type and another one is optical dilatometer (including Laser dilatometer). In the push-rod type dilatometer, the solid sample is placed at the flat surface and a free hanging rod (with a negligible load) touches another side of the sample in the same axis. When the sample expands or shrinks, the push rod also moves accordingly; which is recorded. Some of the temperature dependent processes which show dimensional changes are thermal expansion of the material, crystalline phase transformation, glass softening temperature, polymer softening temperature and glass transition temperature, and powder sintering process etc. For example, thermal expansion coefficient of a material can be obtained. In the powder system, sintering is usually characterized by shrinkage and this shrinkage starts at particular temperature, called onset of sintering. Using the dilatometer, the amount of shrinkage of a powder compact, as a function of temperature and holding time can be accurately determined. Various cash studies have been presented. Dr.Atul S. Deshpande Surface area analysis Information on surface area and porosity is important many applications such as catalysis, separation/ filtration techniques and energy storage applications. Nitrogen sorption method is one of the prominent method for surface area analysis. This talk is focuses on basic aspects of operation, data collection and data analysis. Fundamental of various adsorption theories such as BET and Langmuir theory are also discussed. Dr. Ranjith Ramadurai Photoelectron spectroscopy Photoelectron spectroscopy (PS) is a unique surface characterization technique operating under the principle of photoelectric effect. In this technique, either monochromatic ultra-violet (UV) or x-ray beam is focused on the sample and the kinetic energy of the emitted photo electrons is analyzed. In the case of utilization of UV source it is commonly known as UPS and in the case of X-rays it is known as XPS. In both cases, upon analyzing the kinetic energy of the photoelectron for a known incident energy beam facilitates to calculate the binding energy of that particular photoelectron. The UPS is known for its surface sensitivity and energy resolution and could be utilized to differentiate the electron binding energy from dangling bonds, the surface reconstructed atoms with back bonding and also the bulk atoms. In this talk Silicon (7x7) reconstruction mechanism and methods to confirm the binding the energy state of different atoms involved in reconstruction utilizing UPS was detailed.

6 In the case of XPS the most commonly used sources are Al and Mg K radiation. Due to the probe energy offered by XPS, the core level spectrum of various atoms could be analyzed. In addition, valence band spectrum of semiconductors and hetero junctions, interfacial layers and molecular orbital energy etc. could be analyzed. The model system of silicon forming wide range of interfaces with Gd 2 O 3 a high-k dielectric material was discussed and used as an illustration for the analysis of the spectrum. The detail of change in the binding energy with respect to the change in chemical surrounding of silicon atom was elaborated as a model system. Lab tours In part of the TEQIP-2014 workshop, Lab tour is one of the major event for the participants to give the wider exposure on the various synthesis and characterization techniques available in the IIT Hyderabad. During this event participants had an opportunity to visit the labs of MSME department at permanent and temporary campuses. The participants were given brief demonstration on several characterization techniques like PPMS, FE-SEM, UTM machine, Vickers Hardness Test machine, Impedance Analyzer, DSC, Dilatometer, TGA/DTA, Thin film XRD and several other instruments. We are very much sure that this exposure on several characterization is very much helpful for them to improve their knowledge and pursue their research with higher quality. Feedback session and Relation building The workshop has strengthened the relationship between IIT Hyderabad and the TEQIP funded colleges in Telangana, Andhra and Karnataka. The participants have shown interest in holding in house workshops with the help of IIT H faculty and also utilizing IIT H resources for their research.

7 The interactive session for participant with MSME was very useful to the participants as they could clarify their queries. Conference dinner was also organized on 1 st. It facilitated interaction between TEQIP colleges and also with IITH. The Conclusion Certificates were distributed. Commitments have been made by IIT Hyderabad to support the TEQIP colleges in research and teaching.