Swaminathan Natarajan

Influence of plasma coatings on Inconel 617 for gas turbine applications

Abstract The Inconel 617 with plasma sprayed Al2O3–40%TiO2 (A40T) and NiCr–Cr2O3 coatings were investigated for the hot corrosion behaviour at 1000°C for gas turbine applications. The behaviour of the alloy under the mixed salt environment with and without V2O5 in Na2SO4 and NaCl was analysed by means of mass change per unit area, optical and SEM images along with X-ray diffraction and EDAX. Microstructural and EDAX analyses revealed presence of oxides, rich in Ni and Mo on the surface of the samples. The coated sample exhibited better corrosion resistance in A40T and NiCr – Cr2O3 coatings than bare alloy.

Hot Corrosion Behaviour of Inconel 617 in Mixed Salt Environment at 900 and 1000 °C for Gas Turbine Applications

Abstract An attempt is made to study the hot corrosion behaviour of Inconel 617 under mixed salt environment (Na2SO4, NaCl and/or V2O5) at 900 and 1000 °C. The results were analysed and discussed with respect to mass change, XRD, optical image and SEM/EDAX. The oxide scales are enriched with Ni, Cr, Mo and Co at elevated temperatures. The presence of V2O5 in the salt mixture is found to be the most influencing corrosion species for hot corrosion.

Sliding wear behaviour of plasma sprayed coatings on nickel based superalloy

In this paper, the sliding wear behaviour of nickel based superalloy pin was investigated on disc with two different coatings. The plasma sprayed NiCr–Cr2O3 coating and Al2O3+40%TiO2 (A40T) coating were used on the disc for wear studies. The sliding wear tests were performed on dry conditions at room temperature for a constant sliding velocity for two different applied loads (5 and 10 N). The mass loss, wear resistance and coefficient of friction between the pin and disc were studied during investigations. The wear mechanism involved in the NiCr–Cr2O3 coatings is three-body abrasion and Cr2O3 being the third body between pin and disc. The wear rate is high due to the applied load and suppressed cracks. In A40T coating, the minute debris collected on the surface of the coatings acts as a solid lubricant and reduces friction and wear rate. The SEM and energy dispersive spectroscopy analysis were also carried out for characterisation studies on pin after wear studies. The life of nickel pin on A40T coatings is found superior than the NiCr–Cr2O3 coated disc.

Hot corrosion behaviour of Super 304H for marine applications at elevated temperatures

Purpose The aim of this paper is to study the hot corrosion behaviour of super 304H stainless steel for marine applications. Design/methodology/approach The investigation was carried out with three different combinations of salt mixture (Na2SO4, NaCl and V2O5) at two different temperatures (800 and 900°C). Findings The spalling and growth of oxide layer was observed more with the presence of V2O5 in the salt mixture at 900°C during experimentation than what was observed in 800°C. The mass change per unit area is calculated to study the corrosion kinetics and also the influence of salt mixture. Further, the samples are analysed through materials characterisation techniques using optical image, scanning electron microscope (SEM), energy dispersive X-ray (EDAX) and X-ray diffraction (XRD) analysis. The presence of V2O5 in the salt mixture was the most important influencing species for accelerating hot corrosion. Originality/value SEM, EDAX and XRD analysis confirmed the formation of Fe2O3 and Cr2O3 at 900°C showing contribution in corrosion protection.

System Maps: Integrating Knowledge System Models

When we design and develop a system, knowledge about the problem and solution is typically fragmented across a number of tools and models -- and the minds of the engineering team. Unified system modelling tools capture the overall problem and solution at a certain level of abstraction, but detailed knowledge and decisions remain scattered across multiple environments. A great deal of the time and effort expended on large projects such as the SKA radio-telescope goes into the problem of flowing information across development silos and maintaining consistency among them. We are exploring the possibility of creating SystemMaps, a unified repository for system knowledge that can serve as an underlying integrating layer across the various tools and models. Our goal is to explicate and capture the semantics of the relationships among the various models, to enable consistency checking among them. Our starting point is to organize the space of system models into a dimensional framework, such that consistency relationships among models lie along the dimensions. This paper discusses the dimensional framework, and our proposed research directions for working through the problem of creating SystemMaps using a knowledge-centric approach.

A cyber infrastructure for the SKA Telescope Manager

The Square Kilometre Array Telescope Manager (SKA TM) will be responsible for assisting the SKA Operations and Observation Management, carrying out System diagnosis and collecting Monitoring and Control data from the SKA subsystems and components. To provide adequate compute resources, scalability, operation continuity and high availability, as well as strict Quality of Service, the TM cyber-infrastructure (embodied in the Local Infrastructure - LINFRA) consists of COTS hardware and infrastructural software (for example: server monitoring software, host operating system, virtualization software, device firmware), providing a specially tailored Infrastructure as a Service (IaaS) and Platform as a Service (PaaS) solution. The TM infrastructure provides services in the form of computational power, software defined networking, power, storage abstractions, and high level, state of the art IaaS and PaaS management interfaces. This cyber platform will be tailored to each of the two SKA Phase 1 telescopes (SKA_MID in South Africa and SKA_LOW in Australia) instances, each presenting different computational and storage infrastructures and conditioned by location. This cyber platform will provide a compute model enabling TM to manage the deployment and execution of its multiple components (observation scheduler, proposal submission tools, MandC components, Forensic tools and several Databases, etc). In this sense, the TM LINFRA is primarily focused towards the provision of isolated instances, mostly resorting to virtualization technologies, while defaulting to bare hardware if specifically required due to performance, security, availability, or other requirement.

SKA Monitoring & Control: Challenges & approaches

While there are fundamental similarities to the Monitoring and Control (M&C) problem for any large distributed system, there are also unique needs and challenges resulting from the scale and nature of the Square Kilometer Array (SKA) that need to be understood at the current requirements specification stage. An overarching philosophy for SKA software is to avoid bespoke solutions wherever possible. This requires the development of architectural strategies that address the unique needs by leveraging state-of-the-art approaches and available off-the-shelf solutions. In this paper, we present the current understanding of SKA M&C requirements and challenges, and some early thinking on strategies and philosophies to address them. A generic fully-specifications-driven architecture for M&C is discussed as an interesting possibility.

Electrodeposition of nickel from perchlorate based electrolytes

Nickel is usually electrodeposited from the Watts bath. Other baths like sulphamate and fluoborate are also of industrial importance but are used less commonly. Perchlorate solutions, though examined to some extent in the case of cadmium and lead deposition, have not been experimented upon for deposition of nickel. In this paper certain operational data on perchlorate nickel deposition are presented. As a consequence, the following bath composition is recommended: Nickel 29.2 g/l, perchloric acid 201.0 g/l, ammonium chloride 60-120 g/l, pH 5.5-6.8. The useful current density is 1-5 A/dm 2 and optimum temperature 50°C.

An Attempt at Explicating the Relationship between Knowledge, Systems and Engineering

Software systems often serve as the agents of operation for both enterprise systems and embedded systems. Engineering such systems is a knowledge-centric activity. A clear understanding of the relationship between knowledge, systems and engineering can help us to establish firm theoretical foundations for software and systems engineering. Currently we have a strong intuitive understanding of how knowledge flows into engineering, while our understanding of the relationship between systems and knowledge is part explicit and part tacit. A symptom of this is that we have difficulty in building unified models of large systems such as telescopes and enterprises that span multiple knowledge domains and viewpoints. We are able to build multiple models covering various aspects and particular viewpoints. However, we have challenges in integrating them into a single unified model. Another symptom is that software and systems engineering practice are widely viewed as empirical fields, without sufficiently strong theoretical foundations. This work attempts to explicate and synthesize our common intuitive understanding in this space to develop a conceptual model of the relationships. It then explores the validity of this model by examining the extent to which it is able to explain and illuminate current engineering practices and issues. This is an initial strawman version of the model, presented with a view to obtaining feedback and inputs from the community.

SKA telescope manager: a status update

The international Square Kilometre Array (SKA) project to build two radio interferometers is approaching the end of its design phase, and gearing up for the beginning of formal construction. A key part of this distributed Observatory is the overall software control system: the Telescope Manager (TM). The two telescopes, a Low frequency dipole array to be located in Western Australia (SKA-Low) and a Mid-frequency dish array to be located in South Africa (SKA-Mid) will be operated as a single Observatory, with its global headquarters (GHQ) based in the United Kingdom at Jodrell Bank. When complete it will be the most powerful radio observatory in the world. The TM software must combine the observatory operations based at the GHQ with the monitor and control operations of each telescope, covering the range of domains from proposal submission to the coordination and monitoring of the subsystems that make up each telescope. It must also monitor itself and provide a reliable operating platform. This paper will provide an update on the design status of TM, covering the make-up of the consortium delivering the design, a brief description of the key challenges and the top level architecture, and its software development plans for tackling the construction phase of the project. It will also briefly describe the consortium’s response to the SKA Project’s decision in the second half of 2016 to adopt the processes set out by the Software Engineering Institute (SEI) for system architecture design and documentation, including a re-evaluation of its deliverables, documentation and approach to internal reviews.