Title of Invention

BORON CARBIDE POWDER AND A METHOD OF MANUFACTURE THEREOF

Abstract

A method of manufacturing of boron carbide powder comprising the steps of grinding the carbon and boron oxide powder in the weight ratio of 1:2.66, mixing the ground powder homogeneously, packing the mixture in a graphite crucible and closed by perforated lid, placing the crucible inside a silicon carbide-alumina susceptor and filling the gap with zirconia powder, placing the susceptor in a borosilicate reactor vessel lined with ceramic fiber board insulators, covering the crucible lid with carbon powder, evacuating the reactor vessel and flushing the same with high purity argon before heating the said vessel in a domestic microwave oven (2.45GHz) to a temperature of 1450 degree C for 40 minutes, the temperature being measured by a R - type Pt-PtRh thermocouple after switching off the oven.

Full Text

This invention relates to boron carbide powder and a method of manufacture thereof. Boron carbide (B4C) is well known for its high melting point, outstanding hardness, low specific weight, high modulus, high chemical stability, good wear resistance and high neutron absorption cross section. In addition, boron carbide has been used in armour because of its low specific weight and high impact resistance. Boron carbide can be prepared by a variety of high temperature methods such as carbothermic reduction of boron oxide at over 1600 degree C, direct reaction of boron with carbon, reduction of boron trichloride with methane at a temperature of 1500 degree C employing laser or magnesiothermic reduction of boon oxide in the presence of carbon at 1000 to 1200 degree C. Rapid formation of B4C at a lower temperature using less expensive materials through a simpler process route is receiving lot of attention Microwave synthesis of materials offers the advantages of heating through the entire volume and very efficient transfer of energy. Reaction times are shorter than those required in conventional methods to produce sample having comparable crystallites. A novel method for producing boron carbide using carbon and boron oxide under microwave irradiation within a shorter duration is being presented in this report. The purity of the product has been conformed with X-ray fluorescence spectroscopy (XRF). According to this invention the method of manufacture of boron carbide powder comprises the steps of grinding carbon and boron oxide powder in the weight ratio of 1: 2.66; mixing the ground powder homogeneously; packing the mixture in a graphite crucible and covering with a perforated lid; placing the crucible inside a silicon carbide-alumina susceptor and filling the gap with zirconia powder, placing the susceptor in a borosilicate reactor vessel lined with ceramic fiber board insulator, covering the crucible lid with carbon powder, evacuating the reactor vessel and flushing the same with high purity argon before heating the said vessel in a domestic microwave oven (2.45 GHz) to a temperature of 1450 degree C for 40 minutes, the temperature being measured by a R-type Pt-PtRh thermocouple after switching off the oven. EXAMPLE Carbon and boron oxide powder are ground in the weight ratio of 1:2.66. The ground powder is then mixed homogenously in an agate mortar mixer. The ground mixture is packed tightly in a graphite crucible of 20 mm diameter and 40 mm length and closed with a perforated lid. The crucible is then placed inside a silicon carbide-alumina susceptor and the gap is filled with zirconia powder. The susceptor is then placed in a borosilicate reactor vessel lined with ceramic fiberboard insulators. The crucible is covered with carbon powder. The reactor vessel is evacuated and flushed with high purity argon before heating the said vessel in a domestic microwave oven to a temperature of 1450 degree C at 2.45 GHz for 40 minute, the temperature being measured by an R type Pt- PtRh thermocouple after switching off the oven. The thermocouple is inserted through a hole in the ceramic fiberboard, to measure the temperature. The term and expression in this specification are of description and not of limitation having regard to the scope and ambit of this invention. We claim 1. A method of manufacturing of boron carbide powder comprising the steps of grinding the carbon and boron oxide powder in the weight ratio of 1:2.66, mixing the ground powder homogeneously, packing the mixture in a graphite crucible and closed by perforated lid, placing the crucible inside a silicon carbide-alumina susceptor and filling the gap with zirconia powder, placing the susceptor in a borosilicate reactor vessel lined with ceramic fiber board insulators, covering the crucible lid with carbon powder, evacuating the reactor vessel and flushing the same with high purity argon before heating the said vessel in a domestic microwave oven (2.45GHz) to a temperature of 1450 degree C for 40 minutes, the temperature being measured by a R - type Pt-PtRh thermocouple after switching off the oven. 2. The method as claimed in Claim 1 wherein the temperature was measured by inserting the thermocouple through a hole in ceramic fiberboard insulator. 3. The method is claimed in any one of the preceding Claims wherein the microwave oven is a domestic microwave oven operated at 2.45GHz. 4. A method of manufacture of boron carbide powder substantially as herein described and illustrated by the Example. 5. Boron carbide powder whenever manufactured by a method as claimed in any one of the preceding Claims

Documents:

0566-che-2005 complete specification as granted.pdf

0566-che-2005-claims.pdf

0566-che-2005-correspondnece-others.pdf

0566-che-2005-description(complete).pdf

0566-che-2005-form 1.pdf

0566-che-2005-form 26.pdf

EXAMINATION REPORT REPLY.PDF