Dr Prakash Jadhav, Professor and Head, Department of Mechanical Engineering at SRM University-AP has published a chapter titled “Design Methodologies for Composite Structures in Aircraft Engines” in the book Advanced composites in aerospace engineering applications, Feb 2022, ISBN 978-3-030-88191-7, Springer.

Abstract of the book chapter

Recently there have been many successful attempts to implement the use of fibre-reinforced composite structures in commercial aircraft engines. The author has been part of these efforts while working in the aviation industry. This article describes these efforts to design, analyze, manufacture, and implement the composite structures inside the low-pressure and low-temperature zones of the engine. Very innovative out-of-the-box design methodologies were used to design these components. These efforts elaborate on the design, optimization, and improvement of the composite fan blade, the composite fan platform, and the composite booster blade inside the engine. It focuses on structural design, aerodynamic efficiency, and specific fuel consumption improvement efforts along with the usual reduction of weight targets. This work successfully demonstrates the systematic steps in the design and implementation like preliminary coupon-level simulations, coupon-level manufacturing, coupon/prototype testing, and final part-level simulations followed by part tests.

The target readers for the book are all engineers, professionals and researchers from the aerospace field. Dr Prakash Jadhav’s future research plan is to continue to develop new methodologies to implement more composites into the aerospace industry. The book chapter will be extremely useful for engineers working on the design of composite structures for aerospace applications.

High-entropy alloys (HEAs) are gaining research significance in recent times as they propose novel alloy designs and concepts demonstrating better performance. HEAs constitute multiple principal elements in varying concentrations and combinations to produce new materials with excellent physical properties and superior performance at extreme temperature conditions. Recent studies have brought out a few high-entropy alloys possessing exceptional properties, even capable of challenging the existing theories and models for conventional alloys. However only very little has been explored within this multidimensional space leaving limitless possibilities to be explored and materialized.

Dr Sheela Singh, from the Department of Mechanical Engineering, has been conducting rigorous research in this domain and she has published research articles proposing novel ideas to tweak the properties of HEAs. In one of the articles co-authored by Dr Sheela, “Effect of minute element addition on the oxidation resistance of FeCoCrNiAl and FeCoCrNi2Al high entropy alloy”, published in the journal Advanced Powder Technology, she investigates the effect of Ti0.1 and Ti0.1Si0.1 addition on the high-temperature isothermal oxidation behaviour of dense FeCoCrNiAl and FeCoCrNi2Al high entropy alloys.

Mechanical properties such as hardness & young’s modulus, thermal properties such as melting temperature, specific heat capacity and coefficient of thermal expansion (CTE) were investigated by Nano hardness tester (NHT), differential scanning calorimetry (DSC) and dilatometer, respectively. The phases present in the HEAs produced by hot vacuum pressing and after isothermal oxidation were characterized by X-ray diffraction, Scanning Electron Microscopy and Raman Spectroscopy.

The weight gain recorded after isothermal oxidation for 5,25,50 and 100 hours at 1050°C was found to be parabolic in nature. X-ray diffraction analysis (XRD), as well as Raman spectroscopy analysis of HEA’s oxidized at 1050°C for 100 hours, shows the formation of the Al2O3 phase. A homogeneous thin oxide scale without any discontinuity was observed throughout the cross-section. It has been confirmed that Ti & Si addition in minute amount (0.1 at. % each) improves the mechanical properties and oxidation resistance as well as reduces the waviness of the oxide scale.

Another article co-published by her, “Enhanced Magnetization with Increased Chromium Concentration in FeCoCrxNi2Al High-Entropy Alloy”, in Materials and Science Technology, reports the effect of increasing the concentration of antiferromagnetic element Cr in FeCoCrxNi2Al (x = 0.5, 1.5) High Entropy Alloy (HEA) on their magnetic properties. It was found that the structure and composition of different phases, and the likely degree of spinodal decomposition in the Cr-Fe rich BCC phase significantly affects the magnetic properties.

Interestingly, the sample with Cr concentration x=1.5 showed two times larger saturation magnetization as compared to x=0.5. Furthermore, the magnetization versus temperature response shows a multi-phase character and exhibits distinct behaviour in low temperature and high-temperature regimes in both samples. The obtained soft ferromagnetic behaviour of these HEAs is crucial for the development of a new class of HEA for various applications.

The considerable structural and functional potential, as well as the richness of design, make HEAs promising candidates for new applications prompting further studies in the field. There remains a vast compositional space that is yet to be discovered. New studies have to be initiated finding out effective ways to recognise regions within this space where high-entropy alloys with potentially interesting properties may be lurking. Dr Sheela’s research is a right step in this direction to pave the way for fruitful developments in the future.

The research project titled Development of Novel Gold and Silver Alloys was sanctioned to Prof G S Vinod Kumar from the Department of Mechanical Engineering. The project was sanctioned by Waman Hari Pethe Sons, a leading Gold/Diamond jewellery manufacturing company based in Maharashtra, with a total outlay of Rupees 17 Lakhs. The tenure of the project is two years, from May 2022 to May 2024.

Prof Vinod Kumar’s research interests mainly revolve around the hardening of 22 carats and 24 carats gold for light-weight and high-strength jewellery and the novel processing of light alloy (Al and Mg) foam and studying the structure and properties. He has been intensely involved in the development of technologies for improving the hardness of 22k gold for weight saving and high strength in the cast and hand-made jewellery. This was jointly patented by SRM and Titan. He also has several industrial research partnerships and funded projects to his credit.

The present project aims to develop novel high carat gold (24,22 and 18 carats) for high-strength and light-weight jewellery applications and novel silver alloys (high pure (99%) or sterling silver (92.5%)) having better anti-tarnishing capability. It further aims to develop colour gold alloys (Black, violet and pink gold). The project also involves both the lab-scale and industrial development of the process for scaling up jewellery production of the gold and silver alloys.

A robust body of published works helps advance research capabilities and contribute to the larger research domain. Two latest paper publications from the Department of Mechanical Engineering are co-authored by Prof G S Vinod Kumar and his PhD student, Mr Akshay Devikar.

The first paper, Stabilization and Mechanical Properties of Mg-3Ca and Mg-3Ca/SiC/5p foams alloyed with Beryllium, got published in the Journal of Materials Engineering and Performance and had an impact factor of 2.036.

Liquid processing of Magnesium is complicated due to its uncontrolled flammability in the presence of oxygen. However, owing to the lightweight property of Mg, it can be used as a structural material in various sectors such as naval, aerospace, automobile, biomedical, heat exchangers, and military applications. Therefore, using Ca and Be as alloying elements and oxidation preventers, the researchers produced lightweight Mg foams (of density 0.17 g/cm 3), which float on water. SiC particles provide excellent Mg foam stabilisation as well. The compression tests revealed the highest strength for Mg-3Ca foam containing both Be and SiC. Thus, the burning problem of Mg was overcome by adding Ca and a trace quantity of Be to make lightweight foams, which were strengthened by SiC particles.

Abstract

The present paper investigates the stabilisation of Mg-3Ca alloy and Mg-3Ca/SiC/5p composite foams with and without the addition of 0.12 wt.% beryllium. In Mg-3Ca alloy foam, Be addition has significantly improved the expansion and pore structure. Whereas, in the case of Mg-3Ca/SiC/5p composite foams, the SiC particles stabilised the foam effectively, while Be addition did not show any distinguishable improvement in the foam structure. The formation of BeO and the dense coverage of SiC particles in the gas-solid interface of Mg-3Ca and Mg-3Ca/SiC/5p composite foams, respectively, are the reasons for the foam stabilization. Mg-3Ca/SiC/5p composite foam exhibited the lowest foam density of 0.10 g/cm3. The quasi-static compression test shows that Mg-3Ca-0.12Be/SiC/5p composite foam containing Be exhibited lower foam density and higher normalized compressive strength. The energy absorption capacity per unit foam density in Be containing foams was also higher.

The second paper, the Effect of Beryllium on the stabilization of Mg-3Ca alloy foams, is published in the journal Materials Science and Engineering B with an impact factor of 3.407.

Mg-3Ca alloy foams of density as low as 0.25 g/cm3 were successfully produced via the liquid metal route in an open-air atmosphere with trace Be addition. The stable BeO layer formed at the gas-solid interfaces of pores restricted the Mg + CO2/CO reaction, thereby reducing the gas loss responsible for foaming. Be addition (0.13 wt.%) resulted in a high-volume expansion of Mg-3Ca foam (694 %). Metallic single films also exhibited smooth and crack-free interfaces with Be addition.

Abstract

The present work is the first-ever study where the influence of beryllium (Be) addition on the stability of Mg alloy foam was investigated. Mg-3Ca alloy foams were produced by the liquid processing route with and without Be micro-addition. CaCO3 was used as a blowing agent. Mg-3Ca alloy foam without Be resulted in stable foam but exhibited low expansion with poor foam structure. Be addition significantly increased foam expansion and improved their structure. The expansion and the structure of the Mg foams obtained are comparable with that of commercially available aluminum foams. The XPS analysis confirmed the presence of BeO at the gas-solid interface of Mg foam. Be stabilizes the gas-solid interface of the foam by forming a smooth and crack-free surface of the BeO layer, which prevents the continuous oxidation of liquid foam and minimises the loss of blowing gas, thereby enhancing the stability of Mg-3Ca alloy foams.

Bulletproof vests, Car body parts, Hip and Knee implants, Sound and heat-proof walls in theatres, Naval ship bodies, etc., are some of the applications of the research findings. The researchers have collaborated with Dr Manas Mukherjee (Associate Professor) and his PhD student, Mr Biswaranjan Muduli of the Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, for this work. Stabilisation using other alloying elements and ceramic particles for improving mechanical properties of Mg foams specific to application requirements and establishing structure-property relationship from the point of view of melt viscosity by altering the foaming parameters are the future plans of the research team.

Closed-cell metal foams are crucial to heavy industry machinery as they primarily function as impact-absorbing materials. Stabilizing closed-cell metal foams is a pivotal element in the process of manufacturing closed-cell metal foams. On this note, Prof GS Vinod Kumar from The Department of Mechanical Engineering has published a paper entitled Production, stability, and properties of in-situ Al–5ZrB2 composite foams in the journal Materials Science and Engineering: A with an impact factor of 6.044.

Abstract

Stabilization is an essential requirement to produce closed-cell metal foams. In the melt route of foaming, usually ceramic particles are used as foam stabilizers. For the first time, the present study introduces ZrB2 particles as foam stabilizers. We demonstrate the foaming of in-situ based Al composite containing submicron ZrB2 particles. The effect of foaming temperature and holding time on the structural and mechanical properties of the foams was studied. The composites and foams were characterized using XRD, SEM/EDS, and optical scanning techniques. The mechanical properties of the foams were determined by subjecting the foams to a quasi-static compression test. Submicron ZrB2 particles present in the cell wall and at the gas-solid interface promoted foam stability. All the foams exhibited a good cellular structure with high expansion. Among the foams, the foams prepared at 680 ºC with a holding time of 120 s exhibited the smallest cell size and the best mechanical properties. The structural and mechanical properties of the Al–5ZrB2 foams were found to be comparable to conventional foams.

Novel in-situ ZrB2 particles were produced to form Al-5ZrB2 composites. ZrB2 particles present in the melt tend to stabilize the H2 gas bubbles produced from the decomposition of TiH2. The macrostructure was best observed when foamed at 680 ºC and held for 120 sec. Because of its finer pores ( ̴ 3mm ), excellent compressive strength and energy absorption capacity was exhibited comparable to conventional Al foams.

The paper observes a wide-range of possibilities for the application of in-situ Al–5ZrB2 composite foams to modify bullet proof vests, car body parts, sound and heat proof walls in theatres, naval ship bodies, etc.

Prof Vinod Kumar also discusses the future application of this technique in use of metallic powders as blending agent for effective dispersion of blowing agent in the melt and in the field of compressive and energy absorption studies for Al composite foams.