Title of Invention	A PROCESS FOR THE PREPARATION OF SILICON CARBIDE WHISKERS, PLATELETS AND FIBRES
Abstract	This invention relates to a process for the preparation ion of silicon carbide such as in the form of wishkers,platelets and fibres. The process comprisesion in reacting silicon source with raw cotton fibres in en organic solvent preferably an alcoholic solvent such as n-butanol. The silicon nitride coated cotton fibres so obtained are then subjected to the step of pyrolysis.

Full Text

A PROCESS FOR PREPARATION OF SILICON CARBIDE AND PRODUCTS THEREOF This invention relates to a process for the preparation of silicon carbide. In particular, this invention relates to the process for preparation of silicon carbide such as in the form of fibres, whiskers and platelets and to the products thereof. The need for high temperature insultation and thermally stable reinforcing fibres for aerospace composites lead to the development of variety of fibres. This has demanded research In the development and subsequent industrial manufacture of number of materials like, silica, alumina, zirconia, silicon carbide, silicon nitride and boron nitride, for their suitability as aerospace composites and having high temperature insulation and thermal stability* Silicon carbide among these has gained importance as one of the better alternatives required for these structural applications in the highly specialised area of aerspace composites. The main reasons for selection of silicon carbide fibres for such purposes are their superior strength and good thermal stability. Silicon carbide fibres have been considered as reinforcing fibres far high-performance composite materials. Silicon carbide fibre are generally prepared by chemical vapour deposition techniques, wherein syntheslscd silicon carbide is required to be deposited on a tungsten or carbon core fibre. Another method employed to prepare the silicon carbide fibre is the pyrolysis of organic precursor. This alternative method involves melt spinning of a process for the preparation of silicon carbide and products thereof, as stated herein above, wherein silicon carbide in any desired form, as stated herein above, Is obtBincd in high yields and purity, and the proposed process is convenient, time-saving and economical. Another object of this invention is to propose a process for the preparation of silicon carbide and products thereof, as stated herein above, which avoids preparation of organosilicon polymers, deposition of synthesised silicon cnrt)ide on tungsten or carbon fibre, requirement of chemical vapour deposition techniques, which in-turn requires high tectinical expertise to perform. Still another object of this invention is to propose a process for the preparation of silicon carbide and products thereof, as stated herein above, wherein silicon carbide in any desired form, as stated herein above, Is obtained in high yields and purity, and the proposed process is convenient, time-saving and econoinical. According to this invention there-is provided a process for the preparation of silicon carbide such as in the form of wishkers, platelets and fibres comprising of reacting silicon source with raw cotton fibres in an organic solvent, preferably an alcoholic solvent such as n-butanol, subjecting said silicon nitride coated cotton fibres to the step of pyrolysis. I CLAIM; 1. A process for the preparation of silicon carbide such as in the form of wishkers, platelets and fibres, comprising of reacting silicon source with raw cotton fibres in an organic solvent preferably an alcoholic solvent such as n-butanol, subjecting said silicon nitride coated cotton fibres to the step of pyrolysis. 2. A process as claimed in claim 1 wherein said silicon source Si3N4. 3. A process as claimed in claims 1 and 2 wherein the ratio of said silicon source and raw cotton fibres is 0.3 to 1.0 mole. 4. A process as claimed in claims 1 to 3 said reaction is carried out at room temperature for preferably 0.5 to 2 h and subsequently filtered. 5. A process as claimed in claim 4 wherein said fliterate is treated at temperature of 85 to 90oC, preferably at 90oC for 6-12 h, preferably for 8-10 h. 6. A process as claimed in claims 1 to 6 wherein said pyrolysis is carried out at temperature of 1200-1600 C for 0.25-1 h preferably under the flow of said inert gas, preferably argon gas, at flow rate of 0.1 to 1.0 litre/min and at heating rate of 10-50oC/min. 7. A process as claimed in claims 1 to 6 wherein the by-product is removed by further heating preferably at 650-750oC for preferably 2-3-5 h. 8. A process for the preparation of silicon carbide, such as in the form of wishkers, platelets and fibres substantially as herein described.

Documents:

30-del-1996-abstract.pdf

30-del-1996-claims.pdf

30-del-1996-correspondence-others.pdf

30-del-1996-correspondence-po.pdf

30-del-1996-description (complete).pdf

30-del-1996-form-1.pdf

30-del-1996-form-2.pdf

30-del-1996-form-4.pdf

30-del-1996-gpa.pdf

30-del-1996-petition-others.pdf