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Sengupta S.,Carborundum Universal Limited | Roy T.K.,Carborundum Universal Limited | Ramasubramanian N.,Carborundum Universal Limited
Proceedings of the Unified International Technical Conference on Refractories, UNITECR 2013 | Year: 2014

High alumina cements (HAC) are typically made using hydrated lime & calcined alumina. It results in a mixture of two phases CaAl2O4(CA) & CaAl4O7(CA2) after sintering, the ratio of which depends on chemistry & process conditions. The ratio of the two phases is shown to have a significant effect on the final cement properties. Chemical & physical characterization methods were employed to study the effect of process parameters (shear, throughput etc.) on the formation of these two phases. We found that higher densification at green forming stage leads to the formation of higher levels of CA2 phase at relatively lower temperatures. It is also verified that the product produced with higher levels of CA2 phase, leads to longer setting cement. The results reported here provide insights for tailoring the CA & CA2 phases in high alumina cements, by modifying the process conditions. © 2014 The American Ceramic Society.


Kavitha N.,Carborundum Universal Limited | Balasubramanian M.,IIT | Kennedy A.X.,Carborundum Universal Limited
Journal of Composite Materials | Year: 2013

The effects of particle size and silane treatment on the impact strength are experimentally evaluated for epoxy reinforced with nanometer- and micrometer-sized SiC particles. These nano and microcomposites are fabricated using two different sizes of SiC particles: 60-100 nm and 2-4 mm in diameter. The weight fraction of particles is fixed at 1.5% and the particles are dispersed using ultrasonication. For the purpose of investigating the effect of particle-matrix adhesion on the failure process, composites are fabricated using both as received and silane treated SiC particles and γ- aminopropyltriethoxysilane is used as an organofunctional coupling agent to control adhesion properties. Impact energy is measured using Frank IZod impact pendulum instrument. Additionally, fractured surfaces are observed under a scanning electron microscope to investigate particle bonding, particle dispersion, and toughening mechanism. Particle size along with dispersion and bonding are observed to affect the impact strength. It is observed that both the improved particle dispersion and bonding due to silane treatment lead to an increase in impact strength. With regards to particle size, the composites with nanometer-sized SiC particles are having greater impact strength compared to micrometer-sized particles. © The Author(s) 2012 Reprints and permissions.


Kavitha N.,Carborundum Universal Limited | Balasubramanian M.,Carborundum Universal Limited | Balasubramanian M.,Indian Institute of Technology Madras | Vashistha Y.D.,Carborundum Universal Limited
Transactions of the Indian Ceramic Society | Year: 2011

In this study nanoparticles of SiC were produced through direct pyrolysis of rice husk. The major inorganic component of rice husk is silica, which is highly pure, amorphous, with large surface area and highly reactive. Rice husk used in this study was treated with a silica source in order to enrich the silica content. The synthesis was carried out in an argon atmosphere at 1600°C. Activation energy for the formation of SiC was calculated using Arrhenius equation and found to be 110 kJ.mol-1 for raw rice husk and 139 kJ.mol-1 for treated rice husk. The SEM study of pyrolysed rice husk shows that whiskers formed in the silica rich zone and particles formed in the carbon rich zone. © 2011 The Indian Ceramic Society.


Kavitha N.,Carborundum Universal Limited | Kavitha N.,Indian Institute of Technology Madras | Balasubramanian M.,Indian Institute of Technology Madras | Deval Vashistha Y.,Carborundum Universal Limited
Advanced Materials Research | Year: 2012

Nanoparticles of silicon carbide were produced through direct pyrolysis of stoichiometerically balanced rice husk. Rice husk used in this study was treated with different type and amount of silica source in order to enhance the silica/carbon ratio and thereby increase the yield. The synthesis was carried out in argon atmosphere. To increase the yield, different process parameters were identified and experiments were conducted at various levels using Taguchi design. The process parameters optimized using this design include silica source, pyrolysis temperature, silica content and heating rate. Silicon carbide produced from rice husk was analyzed using X - ray diffraction to identify the phase. From taguchi factor effect diagram it has been found that pyrolysis temperature and silica source plays major role in improving the yield. © (2012) Trans Tech Publications, Switzerland.


Jana P.,Indian Institute of Technology Kharagpur | Jana P.,Carborundum Universal Limited | Jayan P.S.,Carborundum Universal Limited | Mandal S.,Carborundum Universal Limited | Biswas K.,Indian Institute of Technology Kharagpur
Materials Letters | Year: 2015

In-situ grown rare earth hexaaluminate and yttrium aluminium garnet composites were prepared through aqueous sol-gel processing. Dense composites were obtained by pressure-less sintering of calcined gel at 1600 °C for 2 h. Microstructural changes and mechanical properties were studied as a function of garnet phase. Well grown hexaaluminate and garnet phases are homogeneously distributed and form a 'cell and nucleus' type microstructure. Micro-hardness, fracture toughness and elastic modulus of these composites are found to be significantly superior to their parent materials. © 2015 Elsevier B.V.


Kennedy X.,Carborundum Universal Limited | Gowri S.,Anna University
Advanced Materials Research | Year: 2010

Coated abrasives are extensively used for manual operations such us cleaning, deburring, polishing, etc. With the trend towards increased production rates, demands on coated abrasive belts are becoming increasingly severe.. Experimental investigations are to be made to know the effects of the process parameters on the performance of the surface belt grinding process. It is necessary to investigate the effect of flexing along with other input process parameters on output. In the present work the Taguchi's experimental design method is used for performing the belt grinding process on the stainless steel AISI 304 and optimizing the process parameters. Thus, this research aims at right choice of flexing and grinding parameters for the coated abrasive belts. The results were further analysed by Taguchi's signal to noise ratio for finding the optimum process parameters © (2010) Trans Tech Publications, Switzerland.


Jana P.,Indian Institute of Technology Kharagpur | Jana P.,Carborundum Universal Limited | Jayan P.S.,Carborundum Universal Limited | Mandal S.,Carborundum Universal Limited | Biswas K.,Indian Institute of Technology Kharagpur
Journal of Materials Science | Year: 2014

Aqueous sol–gel processing was used to synthesize neodymium-doped magnesium hexaaluminate (La1−xNdxMgAl11O19; x = 0, 0.3, 0.4, 0.5) ceramic powder and subsequently calcined at 1450 and 1600 °C for 2 h. Randomly grown platelets of lanthanum–magnesium hexaaluminate formed a porous interlocking structure. Presence of various percentages of neodymium oxide significantly modifies the porous interlocking microstructure into self-reinforced, card-house-like microstructure. Platelets of rare earth-rich magnesium hexaaluminate were grown preferentially more than the stoichiometric rare earth magnesium hexaaluminate at elevated temperature greater than 1450 °C. Rare earth-rich magnesium hexaaluminate platelets form the skeleton of a card-house structure and the tiny platelets of stoichiometric rare earth magnesium hexaaluminate fill the house. The specific heat capacities, micro-hardness, and fracture toughness were studied in details. © 2014, Springer Science+Business Media New York.


Jana P.,Indian Institute of Technology Kharagpur | Jana P.,Carborundum Universal Limited | Jayan P.S.,Carborundum Universal Limited | Mandal S.,Carborundum Universal Limited | Biswas K.,Indian Institute of Technology Kharagpur
Journal of Crystal Growth | Year: 2014

Advanced sol gel processing was used to synthesize high purity lanthanum hexaaluminate powders. The effect of seeding on the formation of lanthanum hexaaluminate was also studied by seeding the gel. Dry gel was calcined at various temperatures starting from 1100 °C to 1600 °C for 2 h to study the phase evolution. The combine effects of advanced sol gel processing and the presence of seeds promoted the formation of lanthanum hexaaluminate phase at lower temperature than the conventional routes. Lanthanum hexaaluminate phase was detected at 1201 °C and 1300 °C in seeded and un-seeded gels, respectively. The presence of seed decreases the temperature of formation of lanthanum hexaaluminate by 99 °C. Single phase lanthanum hexaaluminate was formed at 1600 °C in seeded gel whereas trace of lanthanum monoaluminate phase still present in un-seeded gel even at 1600 °C.


News Article | August 5, 2014
Site: www.vccircle.com

Murugappa Group firm Carborundum Universal Limited (CUMI) is looking to acquire 49 per cent equity stake its joint venture Cellaris Refractories India Ltd (CRIL) from the Israel-based partner Cellaris Ltd, according to a stock market disclosure. Currently, CUMI owns 51 per cent stake in CRIL. CUMI has signed a letter of intent with Cellaris to buy 6,725,250 equity shares representing the remaining 49 per cent of the equity capital held by Cellaris in CRIL, subject to necessary approvals, the filing said. Following the stake acquisition, CRIL will become the wholly owned subsidiary of CUMI. CRIL was set up for the production of light weight alumina cells for refractory/insulation application. "The change in ownership is expected to speed up scaling up at CRIL and will ensure continuity of operations and product development," CUMI said in the filing. Cellaris is involved in the development, manufacturing and marketing of ceramic foams. It also offers Lite-Cell line of non fibrous, highly porous, ultra light ceramic products for high temperature applications, including furnace insulation, kiln furniture, burner blocks, special atmospheres, light weight kiln cars, flat hanging roof, and heating modules. Founded in 1954, Chennai-based CUMI is a fully vertically integrated abrasives, electro-minerals, ceramics, refractory firm with operations in Australia, Canada, China, India, Middle East, Russia, South Africa, Thailand and the US. In the quarter ended March 31, 2014, CUMI registered a total income from operations of Rs 536.37 crore with a net profit of Rs 26.16 crore. On Tuesday morning, shares of CUMI were trading at Rs 170.20 per share, up 1.58 per cent compared with their previous close, on the BSE.

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