Publications

Publication:

Adhithya Plato Sidharth Arunachalam, Sathyan Subbiah, M Venkateshwaran, P Niketh, Murugaiyan Amirthalingam; Understanding the effect of microgravity on the droplet transfer behavior in gas metal arc welding using drop tower setup. 44th COSPAR Scientific Assembly. Held 16-24 July, 2022

Abstract:

Additive manufacturing has found greater importance in aerospace industry especially in the field of'in-space'manufacturing (ISM), owing to their just-in-time manufacturing ability and capability to fabricate or repair complex parts with ease. Gas metal arc (GMA) welding based wire arc additive manufacturing (WAAM) processes stands out from the other direct energy deposition (DED) processes because of their good deposition rate, and energy efficiency. Compared to reported investigations in terrestrial GMA-WAAM process, understanding the influence of gravity on the droplet transfer phenomenon is much more essential for implementing it in outer space for metal deposition. The droplet frequency and its dimensions are decided by the forces such as gravitational, Lorentz, plasma jet, surface tension and vapor jet acting on the droplets. To study the force balance in the microgravity environment, welding

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Publication:

Adhithya Plato Sidharth A, Niketh P, Venkateshwaran M, Murugaiyan Amirthalingam, Sathyan Subbiah; An apparatus to study arc-wire direct energy metal deposition additive manufacturing process in a drop tower microgravity platform. Rev. Sci. Instrum. 1 January 2024; 95 (1): 015107

https://doi.org/10.1063/5.0178425 

Abstract:

Understanding the mechanisms and dynamics of molten metal droplet transfer within the plasma of a directed energy deposition arc process in microgravity is critical for optimizing the build process with minimal defects. This paper presents a unique experimental setup designed to investigate the transfer of molten metal droplets in the microgravity environment of a drop tower. The primary design of the apparatus revolves around accommodating, within the confines of the drop tower experimental capsule, essential components, including a high-speed camera with necessary filters for capturing molten metal droplets, a consumable electrode wire-arc setup, batteries, a linear traverse stage for single bead deposition, sensors, data acquisition systems, online communication systems, and the control system. These systems are secured to withstand the high deceleration forces at the end of a free fall in the drop tower. The arrangement has demonstrated consistent deposition outcomes, capturing clear images of droplet transfers using a high-speed camera along with voltage, current, and temperature data during the microgravity state induced by free fall. This apparatus will serve as a foundational element in establishing a viable additive manufacturing capability for space applications, as it provides fundamental insights into the transfer of molten metal droplets.

Publication:

Nithya srimurugan and Sathyan Subbiah, "Production of SiC from Lunar and Martian regolith", Oral Presentation, TechConnect World Innovation conference, Washington DC, USA, June 17 - 19, 2024. 

Abstract:

Expeditions into space aim to establish sustainable and enduring exploration of the moon in the near future. This ambitious goal requires a diverse array of technologies for resource extraction from lunar regolith. Given the challenges of planetary surface exploration, including the absence of timely resupply missions, these technologies must minimize reliance on secondary raw materials such as reagents, binders, and electrolytes. In the current landscape of space exploration, lunar regolith, characterized by its composition of various metal oxides, serves as a pivotal raw material. Research efforts till date predominantly focus on additive manufacturing (AM) techniques for processing lunar soil, facilitating the fabrication of intricately shaped parts with a degree of autonomy during production. Notably, process technologies like carbothermal reduction and molten regolith electrolysis have demonstrated efficacy in extracting oxygen from lunar and Martian regolith, marking significant strides toward sustainable resource utilization in extraterrestrial environments. Our research is driven by the potential of extracting silicon carbide (SiC) from loose regolith powder by carbothermal reduction process using methane as the carbonaceous source. Silicon, abundant on both the Moon and Mars in the form of silicon dioxide, serves as the primary precursor for SiC. Methane will be available as a by-product of the Sabatier reaction which is used for processing carbon dioxide in the ISS. Successful implementation of this process could unlock a myriad of manufacturing opportunities, from abrasives and cutting tools to telescopes, high-power semiconductor devices, and radiation-resistant components, all achieved without the need for consumables from Earth, thereby advancing sustainable manufacturing practices. In this study, Lunar and Martian regolith simulants such as LHS-1, LMS- 1 and MGS-1 (Exolith Labs, USA) are used. The LHS-1 and anorthosite powders are mixed with graphite in a predetermined ratio and is spread into a pocket of dimensions 20mm x 20mm x 0.3mm milled on a graphite substrate. The graphite substrate is then placed inside a tubular furnace and heated upto 1600℃ with a holding time of 1 hour at 1600℃. After the heat treatment process, it was observed that the regolith powders got melted and exhibited partial vaporization. The constituents of the vapours include Na, Fe and SiO, with SiO being predominant. The SiO vapour reacts with the deposited carbon that is present at the ends of the tubular furnace and forms SiC. The carbon deposition at the ends of the tube is because of the passage of methane during previous experimental trials. The condensates are scrubbed off from the ends of the tube and is characterized by XRD and Raman spectroscopy for identification of phases. The peaks at wavenumbers 796 cm -1 and 972 cm -1 in the Raman spectra indicates the formation of SiC. Future efforts are ongoing to extract SiC from the reduced samples and to have high pure SiC crystals which can be used in manufacturing abrasives, optics and electronic devices.

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Publication:

Snehal K, Sinha P, Piyush Chaunsali. Development of waterless extra-terrestrial concrete using Martian regolith. Advances in Space Research. 2024Jan1;73(1):933-44. https://doi.org/10.1016/j.asr.2023.07.036 

Abstract:

Human colonization on Martian land is gaining significant attention in space exploration activities that demand in-situ resource utilization in the development of construction and building materials for human habitation. This research explores the utilization of Martian regolith simulant and sulfur to create extra-terrestrial concrete (ETC) with a property suitable for constructing human habitat on Mars. The primary objective of the study is to maximize the utilization of Martian regolith simulant to achieve the desired compressive strength of 25 MPa (average compressive strength specified for concrete used in residential buildings on Earth). Mechanical properties, phase transition, and microstructural characteristics of Martian regolith based-ETC under varied temperature conditions (0 °C, 40 °C, and 50 °C) on Mars were investigated. The optimal mixture proportion of ETC had 70% (by wt.) of Martian regolith and exhibited an average compressive strength of 27 MPa. The formulated ETC could retain up to 25 MPa of compressive strength at 40 ℃ and 50 ℃, and could reach up to 35 MPa at 0 ℃ temperature conditions. The change in compressive strength was attributed to the sulfur sublimation and pore closure brought about by freezing at extreme temperatures, respectively.

Publication:

Neelabh Menaria, Sankaran S, Sathyan Subbiah, Adhithya Plato Sidharth Arunachalam, Venkateshwaran M, Niketh P MEASUREMENT OF METAL FOAM EXPANSION IN A DROP TOWER. 45th COSPAR Scientific Assembly 2024.

Abstract:

Microgravity exerts a significant influence on the characteristics of metal foams by affecting gravity-driven drainage. This effect contributes to achieving homogeneity in the structure of the metal foam, which is considered desirable. Parabolic flights and sounding rockets are employed in most microgravity studies pertaining to metal foams. However, because of their expensive and inaccessible nature, studies in this area are limited. An inexpensive solution to the problem is to use a drop tower. The difficulty encountered when conducting metal foaming experiments in a drop tower lies in the restricted period of microgravity, which limits the time available to observe the phenomena of interest. The objective of this study is to conduct metal foaming in a drop tower and to obtain conclusive insight into metal foam expansion under the influence of microgravity. To achieve this, an ad-hoc setup is developed that can be used for time-constrained experiments involving the measurement of metal foam expansion. This setup can foam multiple metal foam samples at a single time. In this setup, foaming is only allowed in the vertical direction (along the -g axis) and is constricted along the horizontal direction therefore foam expansion is synonymous with an increase in the height of foam in the context of this experiment. A cartridge heater is used in conjunction with a thermocouple to monitor the heating rate, while foam expansion is recorded with the help of a camera. All these components are secured firmly on the deck of the inner capsule with the necessary protection to avoid damage caused by the high g force during the landing of the drop capsule on the airbag. Using relays, the heater, camera, and thermocouple will be activated in a sequence before the drop. Preliminary ground tests (under 1 g) were conducted by performing 30 trials to observe the expansion of metal foam in 2.5 seconds at different intervals of time and to obtain a threshold height after which expansion is uniformly consistent. A drop will be executed once the expanding metal foam crosses this threshold height. Expansion observed during the ground test will be compared with the expansion in the drop tower to quantify the effects of microgravity on the growth rate of foam expansion. This study aims to showcase that even complex experiments such as the measurement of metal foaming expansion can be performed in a drop tower. This will help to accelerate the advancement of research in the field of metal foams 

Publication:

Yashdeep, Sathyan Subbiah, Use of Magnetic fields to impact Glass-Transition and Crystallization during Manufacturing of ZBLAN Optical Fibers. Manufacturing letters, NAMRC 52. 

Abstract:

ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) is the most stable glass among the Heavy Metal Fluoride (HMF) family and has a wide range of applications in medical industry, telecommunication, IR transmission, among others. But, due to crystal formation while manufacturing of ZBLAN fiber its theoretical minimum loss has not been achieved yet. Some techniques such as high cooling rate and microgravity conditions have been utilized to reduce the crystal formation but are challenging to implement during manufacturing of these fibers. Alternatively, magnetic field (MF), also a body force like gravity, is expected to influence the crystal formation mechanism and glass kinetics. In this work, ZBLAN glass is processed under magnetic fields of various intensities while simulating fiber drawing manufacturing process conditions. Then, the processed ZBLAN is analyzed using Differential Scanning Calorimetry (DSC) at varying scanning rates. Various glass kinetics parameters such as activation energy, fragility, and preferred crystallization mechanism in terms of Avrami parameter (n) have been analyzed. The glass transition temperature (Tg) increases for a given sample as scanning rate (β) increases. Samples processed under varying magnetic fields, at the same scanning rate, displayed higher glass transition temperatures. Also, when the magnetic field increases, the activation energy required for glass transition decreases, and the fragility index (m) decreases. There is also a preference for surface crystallization over volume crystallization. These results encourage application of magnetic fields for reducing crystal formation while processing ZBLAN glass.

Publication:

Rahul S, G.K. Suraishkumar, Oxidative stress based startergy for enhancement of bacterioredops in production in Halobacterium Salinarium under microgravity, Techconnect WorldInnovation, DC,USA,2024.

Abstract:

Biological production in microgravity offers potential benefits; however, the effect of microgravity on microbial growth and metabolism varies across species, and its underlying mechanism remains unclear. A better understanding has significant implications for both fundamental research and applied biotechnology. Reactive oxygen species (ROS), such as hydroxyl radicals, nitric oxide, and superoxide, play crucial roles in cellular signaling and defense mechanisms, and their intracellular pseudo-steady-state levels are now accepted as reliable markers of cellular oxidative stress. Our previous studies have demonstrated that ROS can enhance microbial productivity by more than 400 %. Yet, under microgravity conditions, their effects are poorly understood. This study focuses on understanding the impact of oxidative stress on the cellular metabolism of Halobacterium salinarum under simulated microgravity conditions. The aim is to enhance in-space biomanufacturing outcomes by modulating cellular reactive species homeostasis. Our model system is the H. salinarum, known for producing bacteriorhodopsin, a photosensitive transmembrane protein with diverse applications, including the in-space development of improved artificial retinas. We explore the dynamics of reactive oxygen species (ROS) and their impact on H. salinarum cellular metabolism under varying gravity conditions, utilizing a Rotatory Cell Culture System (RCCS) for experimental studies and metabolic modeling techniques. Preliminary findings reveal an 18% reduction in maximum cell concentration under simulated microgravity compared to Earth’s gravity (1g) conditions. We are focusing on oxidative stress-based reasoning for this change by investigating various components of cellular redox homeostasis, like ROS and antioxidants. Further study involves modulating cellular ROS levels and analyzing growth and productivity under different gravity conditions. By integrating these analytical approaches, our study aims to devise a novel ROS-based strategy to enhance productivity in the in-space biomanufacturing of microbial products. Understanding the complex interplay between microgravity, oxidative stress, and microbial metabolism holds significant promise for advancing biotechnological applications in space exploration and utilization.