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

Bulletin of Materials Science

关键词: Hypervelocity radome;    $\beta$-SiAlON;    ceramic composite;    near-net-shape consolidation;    AlN passivation against hydrolysis;    conformal sintering.;   

学科分类：材料工程

来源: Indian Academy of Sciences

【 摘 要 】

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.

【 授权许可】

CC BY