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Ananda Kumar M. G. ¹, Shekhar Kumar M. ¹, Suryanarayana K. ¹, Vynatheya S. ¹, Venkatesh T. R. ¹, Seetharamu S. ¹, Jagannath Nayak ²

Affiliations
1 Materials Technology Division, Central Power Research Institute, Bengaluru - 560080, IN
2 Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka, Surathkal - 575025, IN

Abstract

In India, about 60% of the total power generation comes from thermal power stations operating on fossil fuels like coal and lignite [1]. Presently about 400 million tons of coal and lignite is consumed annually for power generation. Typically, Indian coals have an average ash content of about 45%, thereby leading to generation of around 180 million tons of ash annually as an industrial by product.

Out of the total ash generated, 70 % of this ash comprises of fly ash and the remaining are bottom ash, economizer ash, air-preheater ash, etc. Presently, dry fly ash is being utilized in a big way in value added products like bricks, blocks, pavers, etc., while bulk volumes of fly ash is consumed in blended cement manufacture, different types of concrete, construction of dams, roads, river embankments, etc.

Fly ash also contains about 1.0 % hollow particles called as ‘Cenospheres’ generated during combustion of the pulverized coal at high temperatures in the thermal power plant boilers. Cenospheres is a useful by-product of coal combustion which can be harvested from the ash ponds or by any other methods such as tribo-electric separation, slurry precipitation, pond skimming etc., from fly ash. Fly ash cenospheres are unique in the way that they possess excellent properties such as lightweight, low density, nonmetallic, high melting points. These unique properties make cenospheres a prospective raw material to produce value added products for use in engineering applications. The paper discusses the work carried out at Central Power Research Institute on cenospheres characterization and development of value added products for various applications.

Keywords

Fly Ash Cenospheres, Microspheres, Ash Pond, Alumino-silicate, Comprehensive Characterization, Engineering Applications

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Ananda Kumar M. G. ¹, Seetharamu S. ¹, Jagannath Nayak ²

Affiliations
1 Materials Technology Division, Central Power Research Institute, Bangalore 560 080, IN
2 Department of MME, National Institute of Technology-Karnataka, Surathkal- 575 025, IN

Abstract

Aluminium Metal matrix Composites (AMC) have been fabricated through powder metallurgy route comprising of Aluminum as matrix and reinforced with Cenosphere, a low density material in the form of hollow and porous spheres. The densification of the composite has been carried out in an advanced processing technique called the microwave sintering,which is rapid and economical. AMC with Cenosphere addition of 40 volume % has been prepared and sintered at various temperatures. The sintered composites have been studied for the mineralogical phases by XRD, morphology by SEM and physical properties such as Density, Apparent Porosity and Hardness (BHN). The results obtained have been compared with AMCs that were sintered conventionally. The microwave sintered samples showed better properties in terms of Porosity, Bulk Density and Brinell hardness values compared to the conventionally sintered ones.

Keywords

Cenosphere, Microwave Sintering, Aluminum Metal Matrix Composite, Powder Metallurgy.

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Lakshminarayana Bhatta K. G. ¹, Seetharamu S. ², Sharon Olivera ¹

Affiliations
1 Centre for Emerging Technologies, Jain University, Ramanagarm-562112, IN
2 Central Power Research Institute, Bangalore-560080, IN

Abstract

Carbon dioxide capture and storage (CCS) technology is considered as promising option in the portfolio of mitigation actions for stabilization of atmospheric greenhouse gas concentration as fossil fuels continue to be the major source of energy in foreseeable future. Among the various options for CO₂ capture, the adsorption technology has been widely investigated as a means of an alternative to absorption technology that is having many formidable problems. Recently there is a growing interest in solid sorbents; those can efficiently capture CO₂ in the temperature range of 200-700 °C. Applications of high temperature adsorbents are envisioned mainly in sorption enhanced reformation processes (SERP) and CO₂ removal from hot flue gas/syngas. Lithium ceramics are important class of materials in this category. This paper aims at a review of lithium zirconates and lithium silicates as CO₂ adsorbents. The focus is on various aspects of sorbents such as sorption capacity, mechanism of adsorption, kinetic models, factors affecting the sorbent performance and methodologies developed for performance enhancement. However, CO₂ separating membranes made of lithium-based ceramics are not discussed.

Keywords

CO₂ capture, Lithium zirconates, Lithium silicates, Doping, Adsorption, Synthesis

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V. Bharathi ¹, M. Ramachandra ¹, S. Srinivasa ¹, P. Sampathkumaran ², S. Vynatheya ², Seetharamu S. ²

Affiliations
1 Department of Mechanical Engineering, BMS College of Engineering, Bangalore-560019, IN
2 Materials Technology Division, Central Power Research Institute, Bangalore – 560 080, IN

Abstract

The comparative performance of plain Glass-Epoxy (G-E) system with graphite(2.5wt.%) as filler has been reported for slide wear and friction behavior using pin-on-disc setup under varying loads and sliding velocities. This material is intended for use in coal handling systems. Besides slide wear and coefficient of friction (μ) measurements, examination of worn surface features by scanning electron microscope has been carried out to support the slide wear data. The slide wear data reveal that with increase in sliding speed, wear loss of both G-E composite and G-E plain system increase. Further it is seen that the G-E graphite filled system shows the least wear loss compared to plain G-E system. This trend is observed for all the three loads employed in this work. It is observed that the graphite bearing and plain G-E samples display a rise in the value of μ, when both load and sliding velocity are increased. The coefficient of friction of graphite G-E shows the least compared to plain G-E system irrespective of the load and the sliding velocity employed.

Keywords

Glass-epoxy (G-E), Pin-on-disc, Sliding wear, Graphite filler, SEM observations

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K. Narasimha Murthy ¹, P. Sampathkumaran ², Seetharamu S. ², R. K. Kumar ²

Affiliations
1 Department of Mechanical Engineering, CMR Instituteof Technology, Bangalore, IN
2 Central Power Research Institute, Bangalore - 560 010, IN

Abstract

The influence of 2.0% nickel on thin and section permanent molded austempered ductile iron samples were investigated for abrasion and erosion behavior. The section sizes of samples were varied at two levels viz. 25 mm and 50 mm. Wind turbine hubs which were subjected to wear and erosion were made from thin and thick section PMADI castings. The austempering temperature and time were optimized for improved wear behavior and strength at 3000 C for 60 mins. Nickel additions showed about 7% improvement in the wear resistance of thin section PMADI samples over unalloyed PMADI samples. For the purpose of comparison, sand-cast austempered ductile iron was also evaluated for abrasion, erosion resistance. Thin section (25 mm) PMADI samples subjected to austempering at 3000 C for 60 mins showed improved abrasion and erosion behavior in addition to higher strength values over thick section (50 mm) PMADI and sand cast ADI samples. Further these data were analyzed with structure property correlation and were well supported by light photomicrographs.

Keywords

PMADI, Thin/thick section, Abrasion\erosion and Wind turbine hubs

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Suresh N. ¹, Venkateswaran S. ², Seetharamu S. ³, Sampath Kumaran ³, Ramachandran B. E. ⁴, Praveen Kumar T. N. ¹

Affiliations
1 Dept. of Mechanical Engineering, BMS Institute of Technology, Bangalore -560 064, IN
2 Principal, BMS Institute of Technology, Bangalore -560 064, IN
3 Materials Technology Division, Central Power Research Institute, Bangalore- 560 080, IN
4 Dept. of Chemistry, BMS Institute of Technology, Bangalore -560 064, IN

Abstract

The effect of corrosion on aluminium alloy (LM6) containing ceramic fl y ash based microspheres is investigated in this work. Stir casting route has been employed to disperse 10 % ceramic microspheres as reinforcement in the alloy matrix. Further, the alloy system was subjected to grain refinement, modification as well as combined action of grain refinement and modification. Three sets of LM6 alloy castings were produced in each case, to check for reproducibility. The corrosion resistance was evaluated by immersing the samples in 3% NaCl solution. The pH and electrical conductivity were measured to assess the damage due to corrosion. It was observed that the corrosion resistance decreased in the composite samples subjected to grain refinement, modification, combined action of grain refinement and modification compared to untreated alloy composite. Scanning Electron Microscopy [SEM] has been used to substantiate the corrosion data. On the other hand, mechanical properties namely hardness and ultimate tensile strength improved greatly in the modified samples compared to grain refined and grain refined and modified samples.

Keywords

Metal matrix composites, Ceramic microspheres, LM6 and Corrosion

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