• Ibram Ganesh

      Articles written in Bulletin of Materials Science

    • Aqueous slip casting of MgAl2O4 spinel powder

      Ibram Ganesh

      More Details Abstract Fulltext PDF

      A stoichiometric MgAl2O4 spinel (MAS) powder was synthesized by calcining a compacted mixture of 𝛼-Al2O3 and calcined caustic MgO at 1400°C for 1 h and was surface treated against hydrolysis using an ethanol solution of H3PO4 and Al(H2PO4)3 after fine grinding. Aqueous suspensions with 41–45 vol.% treated powder were prepared using tetra methyl ammonium hydroxide (TMAH) and an ammonium salt of polyacrylic acid (Duramax D-3005) as dispersing agents. These stable suspensions were consolidated in plaster moulds by slip casting (SC) route for the first time. For comparison purposes, the treated powder was also compacted by die-pressing technique after converting into freeze-dried granules and sintered along with slip cast samples at 1550–1650°C for 1–2 h. The MAS ceramics fabricated by slip casting and die-pressing exhibited comparable properties.

    • Novel composites of $\beta$-SiAlON and radome manufacturing technology developed at ARCI, Hyderabad, for hypervelocity vehicles


      More Details Abstract Fulltext PDF

      Keeping the importance of developing suitable radome (a word derived from radar $+$ dome) materials and near-net shape consolidation technique for manufacturing radomes suitable for hypersonic ($\gt$mach 5) radar-guided missilesin India, the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), Hyderabad, hasinitiated an in-house R&D programme and successfully developed a complete process know-how for manufacturing defectfreeprototype $\beta$-SiAlON-based radome structures with all the desired properties. As a part of this R&D programme, totalsix separate sub-projects mentioned below were undertaken and executed: (i) identification of the best composition out of$\beta$-Si$^{6−z}$Al$_z$O$_z$N$_{8−z}$ ($0 ≤ z ≤ 4.1$) solid solution, which possesses a right combination of properties required for radome applications, (ii) designing of an AlN-free precursor mixture for consolidating $\beta$-Si$_4$Al$_2$O$_2$N$_6$ ceramics by following aqueous colloidal processing routes, (iii) development of a process for passivating water-sensitive AlN powder against hydrolysis, (iv) development of aqueous gelcasting (GC) and hydrolysis-assisted solidification (HAS) powder processing routes for consolidating dense $\beta$-SiAlON ceramics using highly solids loaded ($\gt$50 vol%) aqueous slurries, (v) development ofan hydrolysis-induced aqueous gelcasting (GCHAS) process, a novel near-net-shape consolidation technique, to produceradomes with very high-production yields and (vi) development of an economic route for synthesizing the low-dielectricconstant and high strength novel $\beta$-SiAlON-SiO$_2$ ceramic composites. In this paper, (i) the basis for choosing $\beta$-SiAlON based ceramics for hypervelocity radome applications, and (ii) the various bottle-neck problems faced, while executing this entire R&D work and the way they were overcome have been critically analysed and discussed systematically, while citing all the relevant and important references.

  • Bulletin of Materials Science | News

    • Dr Shanti Swarup Bhatnagar for Science and Technology

      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

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