Title of Invention	SILICON CARBIDE-ALUMINA-ALUMINUM NITRIDE COMPOSITE, ABRASIVE PARTICLES AND PROCESS OF PREPARING THE SAME
Abstract	This invention relates to a silicon carbide-alumina-aluminum nitride composite abrasive particles which comprises 1 to 95 weight percent of silicon carbide and 1 to 95 weight percent of a solid solution of alumina and aluminum nitride. This invention also includes a process for preparing silicon carbide-alumina- aluminum nitride composite abrasive particles by preparing a suspension of silicon carbide, an alumina precursor, and a carbon source, seeding the suspension with alpha alumina, separating, grinding calcining and heat treating said gel to obtain the abrasive composites. This invention further includes abrasive articles such as grinding wheels, discs, . bonded and coated abrasive articles like belts, abrasive paper and methods of making them with the composite abrasive particles discussed herein above.

Title of Invention

SILICON CARBIDE-ALUMINA-ALUMINUM NITRIDE COMPOSITE, ABRASIVE PARTICLES AND PROCESS OF PREPARING THE SAME

Abstract

This invention relates to a silicon carbide-alumina-aluminum nitride composite abrasive particles which comprises 1 to 95 weight percent of silicon carbide and 1 to 95 weight percent of a solid solution of alumina and aluminum nitride. This invention also includes a process for preparing silicon carbide-alumina- aluminum nitride composite abrasive particles by preparing a suspension of silicon carbide, an alumina precursor, and a carbon source, seeding the suspension with alpha alumina, separating, grinding calcining and heat treating said gel to obtain the abrasive composites. This invention further includes abrasive articles such as grinding wheels, discs, . bonded and coated abrasive articles like belts, abrasive paper and methods of making them with the composite abrasive particles discussed herein above.

Full Text	This invention relates to silicon carbide-alumina-aluminum nitride composite abrasive particles and processes of preparing the same. A variety of abrasive particles such as diamond particles, cubic boron nitride particles, silicon carbide, fused alumina, and sintered alumina are known in the art. Abrasive particles are either used in the loose form or are incorporated into abrasive articles such as coated abrasive products, bonded abrasive products, non-woven abrasive products. Abrasive particles for a particular abrading application include abrading life, rate of cut, substrate surface finish, grinding efficiency and production cost. Silicon carbide which is conventionally used in abrasives is found to be efficient in grinding cast iron glass and tungston carbide containing material. Hard and strong abrasive grits for use in abrasive wheels, flexible coated abrasive products such as sand paper, and loose abrasives are produced by fiision of alumina containing raw material in an electric ftimace or firing of shaped bodies containing finely divided alumina at a temperature well below the fusion point of the material. Such low temperature process is called sintering. US patent no.3079243 discloses milling of calcined bauxite to produce a raw material of fine particle size which is then fomied into abrasive grit sized particle which are fired at a temperature above 1500°C to form hard, strong, tough pellets of polycrystalline alumina. Seeded sol-gel alumina abrasives are formed by uniformly dispersing submicron sized particles of alpha alumina precursor such as boehmits. The mixture is fired after removing water therefi-om to above conversion temperature required to form alumina, which is then sintered US patent no.4623364 refers to such a process. US patent no.4855,246 discloses a high density micro crystalline composite ceramic abrasive particles containing alumina, gamma alumium oxynitride. The main drawbacks of the present day composite abrasive particles are listed below: 1. Absence of an efficient abrasive showing hardness between the range of silicon carbide abrasives and cubic boron nitride abrasives 2. Present day abrasives are not suitable for abrading both ferrous and non-ferrous bodies. 3. Sintered polycrystalline silicon carbide or silicon carbide composite abrasives similar to polycrystalline alumina are not available. One of the objectives of the present invention is to develop a silicon carbide-alumina-aluminum nitride composite abrasive particles suitable for grinding botli ferrous and non-ferrous material. Abrasives of this invention shows hardness in between silicon carbide and cubic boron nitride which makes it suitable for grinding ferrous and non-ferrous material. Tliese abrasives also exliibit polycrystalline composite structure. Yet another improvement is in the production of cost effective sintered silicon carbide based abrasive composite shapes. Abrasives produced by the processes according to this invention are almost fully dense in nature. This invention relates to a silicon carbide-alumina-aluminum nitride composite abrasive particles which comprises 1 to 95 weiglit percent of silicon carbide and 95 to 1 weigjit percent of a solid solution of alumina and aluminum nitride. The preferred range of silicon carbide is 1 to 85 and 1 to 55 weiglit percent and the preferred range of a solid solution of alumina and aluminum nitride is 1 to 45 weight percent. This composite abrasive particle may have the abrasive particle granules in a homogenous or non-homogeneous solid solution. Tliis invention also includes a process for preparing silicon carbide-alumina-aluminum nitride composite abrasive particles which comprises the steps of preparing a mixed sol suspension of silicon carbide particles, an alumina precursor and a carbon source, the components being present in proportions sufficient to provide a ceramic abrasive particle having 1 to 95 weiglit percent of silicon carbide and 95 to 1 weight percent of solid solution of alumina and aluminum nitride, seeding the suspension with alpha alumina to gel said mixed sol, separating and dr>ing said gel crushing and sieving the same to provide sized granules and thereafter calcining the same at a temperature in the range of 600^C to 1200'C followed by heat treatment in nitrogen or inert atmosphere at a temperature above 1600°C. The calcined granules may be optionally shaped into a body and heated at a temperature above 1600oC in a nitrogen or inert atmosphere and then ground and classified to obtain tlie abrasive particles. Carbon source in the said process may be carbon, or carbon generating compounds such as glycerol, polyvinyl alcohol polyvinyl pyrolidine and sucrose. The drying of the granules prior to calcining may be carried out in an ambient, nitrogen or inert atmosphere. Water soluble aluminum compounds such as alumina nitrate and aluminum chloride in tlie concentration ranging from 0.5 N to 5,0 N may be used as a source of aluminum. This invention includes a method of producing bonded abrasives which comprises mixing the silicon carbide-alumina-aluminum nitride composite abrasive particles with conventional abrasive bonding mateiials such as polymer, resins, ceramic, metal powders either alone or in combination to form a bonded abrasive article such as grindmg wheels or discs. Silicon carbide, aluminum oxide, sol-gel alumina, cubic boron nitride, diamond, zirconia, silicon nitride, zirconium toughened alumina, tungston carbide and other conventional abrasives may be added either alone or in combination for making these abrasives. The following examples illustrating the process of preparing the silicon carbide-ahimina-aluminum nitrate composite according to the invention. Example 1 300 g of Sic of surface area 1 nr/g is dispersed in 5000 cc of 1 (N) aluminum monohydrate sol and 9 g of carbon black is mixed thorou^ly. The pH of the medium is kept at 3.5 by adding 70 wt% of niti'ic acid. The suspension is stirred for 15 minutes and 50 g of 25 wt% aluminum nitrate solution is added while stirring. The whole mixture is allowed to age for 24 hours to complete the homogeneous gelation. Tlie gelling mixture is kept in circulating air-oven for 24 hours at 90oC for oven-drying. The oven-dried gel is crushed and sieved tlirougli 200 mesh, Tlie sieved fraction is calcined at lOOO^C in flowing nitrogen atmosphere. The calcined gel is again crushed, passed through 200 mesh sieve, shaped by any conventional method and fired at 2000^C under a nitrogen gas pressure of 20 atmosphere into an impervious graphite crucible for sintering. The sintered bodies is cnished and classified and used as abrasive grain capable of grinding both ferrous and non ferrous material. Example 2 400 g of SiC of surface area I m"/g is dispersed in 4000 cc of I (N) aluminum monohydrate sol and 15 g of carbon black is mixed thoroughly. The pH of the medium is kept at 3.5 by adding 70 wt% of nitric acid. The suspension is stirred for 15 minutes and 50 g of 25 v\t% aluminum nitrate solution is added while stirring. The whole mixture is allowed to age for 24 hours to complete the homogeneous gelation. The gelling mixlure is kept in circulating air-oven for 24 hours at 90oC for oven-drying. The oven-dried gel is crushed and sieved through 200 mesh. The sieved fraction is calcined at lOOOoC in flowing nitrogen atmosphere. The calcined gel is again crushed, passed through 200 mesh sieve, shaped by any conventional method and fired at 2000oC under a argon gas pressure of 10 atmosphere into an impervious graphite crucible for sintering. The sintered shapes is crushed and classified and used as abrasive grain capable of grinding both ferrous and non ferrous material. This invention further includes a method of making sintered articles which comprises shaping the calcined silicon carbide-alumina-aluminum nitride composite abraiiive paiticles after calcination by pressing, slip casting, tape casting, injection moulding and the like with subsequent heat treatment of the shaped mass at a temperature above 1650°C in an atmosphere of nitrogen or inert gas. The heat treatment may be carried out for a period of 1 to 48 hours and may be done in impervious container for controlling the vapour pressure. It should be noted that the heat treatment in this process must be atleast 50oC above the heat treating temperature for the calcimining step in the preparation of the composite abrasive particles. Heat treatment may be etYected at a nitrogen gas pressure of 2 atmosphere to 100 atmosphere to minimize volatilization. Calcined granules in the range of 0.5 to 20 micron may be used in this method. Furtlier, this invention includes a method of making bonded and coated abrasive products having a backing coated with atleast one layer of bonded abrasive having silicon carbide-alumina-aluminum nitride composite abrasive particles disclosed herein above. Obvious equivalents and alternatives known to persons skilled in tlie art aie not excluded from the scope of this invention and the appended claims. WE CLAIM: 1. Silicon carbide - alumina - aluminum nitride composite abrasive particles comprising upto 1 to 95 weight percent of silicon carbide and upto 1 to 95 weight percent of a solid solution of alumina and aluminum nitride. 2. The silicon carbide - alumina - aluminum nitride composite abrasive particle as claimed in claim 1 which has 1 to 85 and 1 to 55 weiglit percent of silicon carbide and 1 to 45 weiglit percent of alumina and aluminum nitride. 3. The silicon carbide - alumina - aluminum nitride composite abrasive particle as claimed in claims 1 or 2 comprising conventional abrasives such as ceramics, metal powders, cubic boron nitride, diamond as optional constituents. 4. A process for preparing silicon carbide-alumina-aluminum nitride composite abrasive particles comprising the steps of preparing a mixed sol suspension of silicon carbide particles, an alumina precursor and a carbon source, the components being present in proportions sufficient to provide ceramic abrasive particles of having 1 to 95 weight percent of silicon carbide and 1 to 95 weight percent of solid solution of alumina and aluminum nitride, seeding the suspension with alpha alumina to gel said mixed sol. separating and drying said gel, crushing and sieving the same to provide sized granules, and thereafter calcining the same at a temperature range of 600°C to 1200^C followed by heat treatment in nitrogen atmosphere above 1600°C. 5. A process as claimed in claim 4 wherein the calcined granules are sliaped into bodies before sintering and the sintered body is ground and classified tor obtainign the abrasive. 6. The process as claimed in claim 4 wherein said carbon source is carbon black or carbon generating precursors such as glycerol, polyvinyl alcohol, polyvinyl pyrolidine, sucrose and the like. 7. The process as claimed in claims 4 to 6 wherein said granules are dried prior to calcining in an ambient/nitrogen/or inert atmosphere. 8. The process as claimed in claims 4 to 7 wherein water soluble aluminum compounds such as aluminum nitride and/or aluminum chloride in the concentration ranging from 0.5(N) to 5.0(N) are the source of aluminum. 9. A method of producing bonded abrasive articles comprising mixing the silicon carbide-alumina-aluminum nitride composite abrasive particles as claimed in claims 1 to 3 with conventional abrasive bonding materials such as polymer, resins, ceramics and metal powders either alone or in combination to form a bonded abrasive articles such as grinding wheel or discs. 10. The method as claimed in claim 9 wherein known abrasives such as silicon carbide, aluminum oxide, sol-gel alumina, cubic boron nitride, diamond, zirconia and zirconia toughened alumina, tungston carbide are optionally added before forming said bonded abrasive article. 11. Grinding wheels made by a method as claimed in any one of the claims 9 or 10. 12. A method of making a sintered abrasive article comprising shaping tlie calcined silicon carbide-alumina-aluminum nitride composite abrasive particles as claimed in claims 1 to 3 by pressing, slip casting, tape casting and injection moulding with subsequent heating of said shaped article at a temperature above 1650°C in an atmosphere of nitrogen or ineit gas. 13. The method as claimed in claim 12 wherein said heat treatment is carried out for a period of 1 to 48 hours in an impervious container. 14. The method as claimed in claims 12 and 13 wherein said heat treatment temperature is at least 50^C above the calcination temperature in the method of making said abrasive particle, 15. The metliod as claimed in claims 12 to 14 wherein said heat treatment is effected at a nitrogen gas pressure of 2 atmosphere to 100 atmosphere. 16. Tlie method as claimed in claims 12 to 15 wherein calcined granules in the range of 0.5 to 20 microns are subjected to shaping and sintering. 17. A method of making bonded and coated abrasive products wherein a backing is coated with at least one layer of bonded abrasives having silicon carbide alumina-aluminum nitride composite abrasive particles as claimed in claims 1 to 3. 18. Bonded and coated abrasive articles when made by a method as clauned in claim 17. 19. Silicon carbide-alumina-aluminum nitride composite abrasive particles substantially as herein described.

Full Text

This invention relates to silicon carbide-alumina-aluminum nitride composite abrasive particles and processes of preparing the same.
A variety of abrasive particles such as diamond particles, cubic boron nitride particles, silicon carbide, fused alumina, and sintered alumina are known in the art. Abrasive particles are either used in the loose form or are incorporated into abrasive articles such as coated abrasive products, bonded abrasive products, non-woven abrasive products. Abrasive particles for a particular abrading application include abrading life, rate of cut, substrate surface finish, grinding efficiency and production cost. Silicon carbide which is conventionally used in abrasives is found to be efficient in grinding cast iron glass and tungston carbide containing material. Hard and strong abrasive grits for use in abrasive wheels, flexible coated abrasive products such as sand paper, and loose abrasives are produced by fiision of alumina containing raw material in an electric ftimace or firing of shaped bodies containing finely divided alumina at a temperature well below the fusion point of the material. Such low temperature process is called sintering.
US patent no.3079243 discloses milling of calcined bauxite to produce a raw material of fine particle size which is then fomied into abrasive grit sized particle which are fired at a temperature above 1500°C to form hard, strong, tough pellets of polycrystalline alumina.
Seeded sol-gel alumina abrasives are formed by uniformly dispersing submicron sized particles of alpha alumina precursor such as boehmits. The mixture is fired after removing water therefi-om to above conversion temperature required to form alumina, which is then sintered US patent no.4623364 refers to such a process. US patent no.4855,246 discloses a high density micro crystalline composite ceramic abrasive particles containing alumina, gamma alumium oxynitride.

The main drawbacks of the present day composite abrasive particles are listed below:
1. Absence of an efficient abrasive showing hardness between the range of silicon carbide abrasives and cubic boron nitride abrasives
2. Present day abrasives are not suitable for abrading both ferrous and non-ferrous bodies.
3. Sintered polycrystalline silicon carbide or silicon carbide composite abrasives similar to polycrystalline alumina are not available.
One of the objectives of the present invention is to develop a silicon carbide-alumina-aluminum nitride composite abrasive particles suitable for grinding botli ferrous and non-ferrous material. Abrasives of this invention shows hardness in between silicon carbide and cubic boron nitride which makes it suitable for grinding ferrous and non-ferrous material. Tliese abrasives also exliibit polycrystalline composite structure. Yet another improvement is in the production of cost effective sintered silicon carbide based abrasive composite shapes. Abrasives produced by the processes according to this invention are almost fully dense in nature.
This invention relates to a silicon carbide-alumina-aluminum nitride composite abrasive particles which comprises 1 to 95 weiglit percent of silicon carbide and 95 to 1 weigjit percent of a solid solution of alumina and aluminum nitride.
The preferred range of silicon carbide is 1 to 85 and 1 to 55 weiglit percent and the preferred range of a solid solution of alumina and aluminum nitride is 1 to 45 weight percent. This composite abrasive particle may have the abrasive particle granules in a homogenous or non-homogeneous solid solution.

Tliis invention also includes a process for preparing silicon carbide-alumina-aluminum nitride composite abrasive particles which comprises the steps of preparing a mixed sol suspension of silicon carbide particles, an alumina precursor and a carbon source, the components being present in proportions sufficient to provide a ceramic abrasive particle having 1 to 95 weiglit percent of silicon carbide and 95 to 1 weight percent of solid solution of alumina and aluminum nitride, seeding the suspension with alpha alumina to gel said mixed sol, separating and dr>ing said gel crushing and sieving the same to provide sized granules and thereafter calcining the same at a temperature in the range of 600^C to 1200'C followed by heat treatment in nitrogen or inert atmosphere at a temperature above 1600°C.
The calcined granules may be optionally shaped into a body and heated at a temperature above 1600oC in a nitrogen or inert atmosphere and then ground and classified to obtain tlie abrasive particles.
Carbon source in the said process may be carbon, or carbon generating compounds such as glycerol, polyvinyl alcohol polyvinyl pyrolidine and sucrose. The drying of the granules prior to calcining may be carried out in an ambient, nitrogen or inert atmosphere. Water soluble aluminum compounds such as alumina nitrate and aluminum chloride in tlie concentration ranging from 0.5 N to 5,0 N may be used as a source of aluminum.
This invention includes a method of producing bonded abrasives which comprises mixing the silicon carbide-alumina-aluminum nitride composite abrasive particles with conventional abrasive bonding mateiials such as polymer, resins, ceramic, metal powders either alone or in combination to form a bonded abrasive article such as grindmg wheels or discs.

Silicon carbide, aluminum oxide, sol-gel alumina, cubic boron nitride, diamond, zirconia, silicon nitride, zirconium toughened alumina, tungston carbide and other conventional abrasives may be added either alone or in combination for making these abrasives.
The following examples illustrating the process of preparing the silicon carbide-ahimina-aluminum nitrate composite according to the invention.
Example 1
300 g of Sic of surface area 1 nr/g is dispersed in 5000 cc of 1 (N) aluminum monohydrate sol and 9 g of carbon black is mixed thorou^ly. The pH of the medium is kept at 3.5 by adding 70 wt% of niti'ic acid. The suspension is stirred for 15 minutes and 50 g of 25 wt% aluminum nitrate solution is added while stirring. The whole mixture is allowed to age for 24 hours to complete the homogeneous gelation. Tlie gelling mixture is kept in circulating air-oven for 24 hours at 90oC for oven-drying. The oven-dried gel is crushed and sieved tlirougli 200 mesh, Tlie sieved fraction is calcined at lOOO^C in flowing nitrogen atmosphere. The calcined gel is again crushed, passed through 200 mesh sieve, shaped by any conventional method and fired at 2000^C under a nitrogen gas pressure of 20 atmosphere into an impervious graphite crucible for sintering. The sintered bodies is cnished and classified and used as abrasive grain capable of grinding both ferrous and non ferrous material.

Example 2
400 g of SiC of surface area I m"/g is dispersed in 4000 cc of I (N) aluminum monohydrate sol and 15 g of carbon black is mixed thoroughly. The pH of the medium is kept at 3.5 by adding 70 wt% of nitric acid. The suspension is stirred for 15 minutes and 50 g of 25 v\t% aluminum nitrate solution is added while stirring. The whole mixture is allowed to age for 24 hours to complete the homogeneous gelation. The gelling mixlure is kept in circulating air-oven for 24 hours at 90oC for oven-drying. The oven-dried gel is crushed and sieved through 200 mesh. The sieved fraction is calcined at lOOOoC in flowing nitrogen atmosphere. The calcined gel is again crushed, passed through 200 mesh sieve, shaped by any conventional method and fired at 2000oC under a argon gas pressure of 10 atmosphere into an impervious graphite crucible for sintering. The sintered shapes is crushed and classified and used as abrasive grain capable of grinding both ferrous and non ferrous material.

This invention further includes a method of making sintered articles which comprises shaping the calcined silicon carbide-alumina-aluminum nitride composite abraiiive paiticles after calcination by pressing, slip casting, tape casting, injection moulding and the like with subsequent heat treatment of the shaped mass at a temperature above 1650°C in an atmosphere of nitrogen or inert gas.

The heat treatment may be carried out for a period of 1 to 48 hours and may be done in impervious container for controlling the vapour pressure. It should be noted that the heat treatment in this process must be atleast 50oC above the heat treating temperature for the calcimining step in the preparation of the composite abrasive particles. Heat treatment may be etYected at a nitrogen gas pressure of 2 atmosphere to 100 atmosphere to minimize volatilization. Calcined granules in the range of 0.5 to 20 micron may be used in this method.
Furtlier, this invention includes a method of making bonded and coated abrasive products having a backing coated with atleast one layer of bonded abrasive having silicon carbide-alumina-aluminum nitride composite abrasive particles disclosed herein above.
Obvious equivalents and alternatives known to persons skilled in tlie art aie not excluded from the scope of this invention and the appended claims.

WE CLAIM:
1. Silicon carbide - alumina - aluminum nitride composite abrasive particles comprising upto 1 to 95 weight percent of silicon carbide and upto 1 to 95 weight percent of a solid solution of alumina and aluminum nitride.
2. The silicon carbide - alumina - aluminum nitride composite abrasive particle as claimed in claim 1 which has 1 to 85 and 1 to 55 weiglit percent of silicon carbide and 1 to 45 weiglit percent of alumina and aluminum nitride.
3. The silicon carbide - alumina - aluminum nitride composite abrasive particle as claimed in claims 1 or 2 comprising conventional abrasives such as ceramics, metal powders, cubic boron nitride, diamond as optional constituents.
4. A process for preparing silicon carbide-alumina-aluminum nitride composite abrasive particles comprising the steps of preparing a mixed sol suspension of silicon carbide particles, an alumina precursor and a carbon source, the components being present in proportions sufficient to provide ceramic abrasive particles of having 1 to 95 weight percent of silicon carbide and 1 to 95 weight percent of solid solution of alumina and aluminum nitride, seeding the suspension with alpha alumina to gel said mixed sol. separating and drying said gel, crushing and sieving the same to provide sized granules, and thereafter calcining the same at a temperature range of 600°C to 1200^C followed by heat treatment in nitrogen atmosphere above 1600°C.
5. A process as claimed in claim 4 wherein the calcined granules are sliaped into bodies before sintering and the sintered body is ground and classified tor obtainign the abrasive.

6. The process as claimed in claim 4 wherein said carbon source is carbon black or carbon generating precursors such as glycerol, polyvinyl alcohol, polyvinyl pyrolidine, sucrose and the like.
7. The process as claimed in claims 4 to 6 wherein said granules are dried prior to calcining in an ambient/nitrogen/or inert atmosphere.
8. The process as claimed in claims 4 to 7 wherein water soluble aluminum compounds such as aluminum nitride and/or aluminum chloride in the concentration ranging from 0.5(N) to 5.0(N) are the source of aluminum.
9. A method of producing bonded abrasive articles comprising mixing the silicon carbide-alumina-aluminum nitride composite abrasive particles as claimed in claims 1 to 3 with conventional abrasive bonding materials such as polymer, resins, ceramics and metal powders either alone or in combination to form a bonded abrasive articles such as grinding wheel or discs.
10. The method as claimed in claim 9 wherein known abrasives such as silicon carbide, aluminum oxide, sol-gel alumina, cubic boron nitride, diamond, zirconia and zirconia toughened alumina, tungston carbide are optionally added before forming said bonded abrasive article.
11. Grinding wheels made by a method as claimed in any one of the claims 9 or 10.
12. A method of making a sintered abrasive article comprising shaping tlie calcined silicon carbide-alumina-aluminum nitride composite abrasive particles as claimed in claims 1 to 3 by pressing, slip casting, tape casting and injection moulding with subsequent heating of said shaped article at a temperature above 1650°C in an atmosphere of nitrogen or ineit gas.

13. The method as claimed in claim 12 wherein said heat treatment is carried out
for a period of 1 to 48 hours in an impervious container.
14. The method as claimed in claims 12 and 13 wherein said heat treatment
temperature is at least 50^C above the calcination temperature in the method of
making said abrasive particle,
15. The metliod as claimed in claims 12 to 14 wherein said heat treatment is
effected at a nitrogen gas pressure of 2 atmosphere to 100 atmosphere.
16. Tlie method as claimed in claims 12 to 15 wherein calcined granules in the
range of 0.5 to 20 microns are subjected to shaping and sintering.
17. A method of making bonded and coated abrasive products wherein a backing is
coated with at least one layer of bonded abrasives having silicon carbide
alumina-aluminum nitride composite abrasive particles as claimed in claims 1
to 3.
18. Bonded and coated abrasive articles when made by a method as clauned in
claim 17.
19. Silicon carbide-alumina-aluminum nitride composite abrasive particles
substantially as herein described.

Documents:

042-che-2003-abstract.pdf

042-che-2003-claims duplicate.pdf

042-che-2003-claims original.pdf

042-che-2003-correspondnece-others.pdf

042-che-2003-correspondnece-po.pdf

042-che-2003-description(complete) duplicate.pdf

042-che-2003-description(complete) original.pdf

042-che-2003-form 1.pdf

042-che-2003-form 19.pdf

042-che-2003-form 26.pdf

042-che-2003-form 3.pdf

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Patent Number

198888

Indian Patent Application Number

42/CHE/2003

PG Journal Number

23/2006

Publication Date

09-Jun-2006

Grant Date

21-Feb-2006

Date of Filing

14-Jan-2003

Name of Patentee

M/S. CARBORUNDUM UNIVERSAL LTD

Applicant Address

"TIAM HOUSE" NO. 72,(OLD NO. 28), RAJAJI SALAI, CHENNAI 600 001

Inventors:

#	Inventor's Name	Inventor's Address
1	SANTANU MANDAL	C/O. CUMI RESEARCH CENTRE,CARBORUNDUM UNIVERSAL LTD., "TIAM HOUSE" NO. 72,(OLD NO. 28), RAJAJI SALAI, CHENNAI 600 001
2	VEIRAVAN ANNAMALAI	C/O. CUMI RESEARCH CENTRE, CARBORUNDUM UNIVERSAL LTD., TIAM HOUSE NO. 72,(OLD NO. 28), RAJAJI SALAI, CHENNAI 600 001
3	BALACHANDRAN SUBRAMANIAN	C/O. CUMI RESEARCH CENTRE, CARBORUNDUM UNIVERSAL LTD., TIAM HOUSE NO. 72,(OLD NO. 28), RAJAJI SALAI, CHENNAI 600 001

PCT International Classification Number

C09C 1/68

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA