Title of Invention

"A PROCESS FOR MAKING NEW CORDIERITE-SPINEL COMPOSITE USING A NOVEL SYNERGISTIC COMPOSITION"

Abstract A process for making new Cordierite-Spinel composites using a novel composition. The present invention provides a process for making new Cordierite-Spinel composites using a novel composition comprising Garnet sand 50 - 60 wt%, Talc 15 - 25 wt% , Clay 10 - 20 wt%, Nucleating Agents 0-10 wt%. The process comprises the steps of mixing a binding agent with the novel composition and ageing for 20-24 hours after granulation, compacting the powder by conventional methods used in ceramic fabrication, drying at the unfired compacts at 110° -120°C followed by firing at a temperature in the range of 1100°-1200°C for a period in the range of 1 to 3 hours to get the new Cordierite-Spinel composites.
Full Text The present invention relates to a process for making
Cordierite-Spinel composites using a novel synergistic composition
from garnet beach sana and a process for making the new Cordierite-Spinel composites.
The Cordierite-Spinel composites are mainly used as structural material,
electroceramics, kiln furniture.
Cordierite, a stable material can be easily obtained from materials such as
pure oxide , carbonate, any type of clay, talc, sepiolite for which reference
may be made to P. Grosjean, Interceram, Vol 42(1), 1993 (11-15) wherein the
cordierite is made by using Luzenac talc and a very refractory pure kaolinite.
Reference may also be made to L.D. Zobina, G. D. Semchenko, Refractories
Jr. (Jan-Feb), 72-75, 1983, wherein cordierite has been developed by
Shavrov clay and other two Types of kaolin. Reference may be made to £.
Medvedovski, Interceram Vol 45(2), 82-86 (1396), wherein cordierite has
been developed by using a MgO containing component and ciay and
aiuminosilicate fluxes.
The drawbacks of the above processes for making cordierite are given beiow
1. The sintering temperature in all the above cases are high and in the
temperature range 1300 -1350°C.
2. Beneficiation of raw materials are required prior to processing.
3. Lower mechanical strength due to inherent microstructurai defects.
5. High shrinkage and deformation. 6. Shorter firing range.
To the best of our knowledge, no such literature is available on Cordierite-Spinel composite material.
The main object of the present invention is to provide a composition useful for making new Cordierite-Spinel composites from garnet beach sand.
Another object of the present invention is to provide a process for making new Cordierite-Sponel composites from garnet beach sand which obviates the drawback as detailed above.
Another object of the present invention is to improve mechanical properties of the product.
Still another object of the present invention is to eliminate the step of beneficiation of raw materials used.
Yet another object of the present invention is to widen the firing range.
The composition of the present invention is not a mere admixture but a synergistic mixture having properties which are different and distinct from the mere aggregation of the properties of the individual ingredients.
Accordingly the present invention provides a composition useful for making new Cordierite-Spinel composites from garnet beach sand which comprises:
Garnet sand 50 - 60 wt%
Talc 15-25wt%
Clay 10-20wt%
Nucleating Agents 0-10 wt%
In an embodiment of the present invention the garnet sand used may have the following characteristics-

(Table Removed)
In an embodiment of the present invention the clay used may have the following characteristics-

(Table Removed)
In an embodiment of the present invention the nucleating agent used may be transition metal oxides, Zirconium oxide, Titanium oxide. Accordingly the present invention provides a process for making new Cordierite-Spinel composites using a novel synergistic composition comprising 50 - 60 wt% garnet sand, 15-25 wt% talc, 10-20 wt% clay, 0-10 wt% nucleating agents , which comprises grinding of garnet sand such as herein described, for a period in the range of 12 - 35 hours and sieving with 300 BS mesh size, drying the said ground garnet sand, proportioning and thorough mixing of the ground garnet sand with talc, clay and nucleating agents such as herein described , for 4-5 hours, sieving through 100 mesh BS , mixing the resultant with a binding agent as defined herein, granulating and ageing for 20-24 hours after granulation, compacting the powder by conventional methods used in ceramic fabrication, drying at the unfired compacts at 110° -120°C followed by firing at a temperature in the range of 1100°-1200°C for a period in the range of 1 to 3 hours to get the new Cordierite-Spinel composites In an embodiment of the present invention clay and talc may be ground to pass 300 BS mesh.
In an embodiment of the present invention binding agent used may be such as Polyvinyl alcohol, molasses.
The details of the process of the present invention are given below :
1. Garnet sand is ground in ball mill with water for a period of 12-35 hours to
pass through a 300 mesh size.
2. The wet ground garnet sand is dried.
3. 50-60% of the fine garnet sand is dry mixed with 15-25% talc, 10-20%
clay and 0-10% nucleating agents for 4 to 5 hours.
4. The final mix is sieved through 100 mesh B.S.
5. The binding agent such as molasses or polyvinyl alcohol is added to the
final mix and granulation done and kept for 24 hours for ageing.
6. The granulated mix is pressed in a shape of pellet and bars by usual
methods of pressing.
7. The pressed shapes are dried in an oven at 110 -120°C and fired at
temperature in the range of 1100-1200°C for a period in the range of 1 to 3
hours.
The process of the present invention can be used to produce new Ccrdierite-Spinel composites of various shapes and sizes required for application as structural materials, kiln furnitures.
Garnet generally transform to substitutional spinel solid solution during sintering. This in-situ spinel formation has been utilised to form a new Cordierite-Spine! composite to achieve an excellent property combination at much lower temperature. In the present work talc and clay are mixed with the garnet sand which fired at much lower temperature (1100 - 1200°C) and the ultimate product found, primarily consist of cordierite and spinel which do not
coexist in nature. The crystallisation usually progresses through intermediate metastable stage during heat treatment and finally the stable phases developed which mainly depend on the chemical composition and thermal history of the base materials, as well as the addition of small amount of nucleating agents. In this case, both low temperature form ((3-cordierite) and metastable form (fi-cordierite) readily converts to the stable form (a cordierite) in the temperature range of 1100-1200°C when heated in air. The transition metal oxides or the nucleating agents are added to the mix in order to accelerate the formation of major cordierite phase at much lower temperature. The other major phase developed is spinel and there is a continuous replacement series from spinel to hercynite. The melting point of spine! is very high (2135°C) and also show much superior properties alongwith cordierite compared to normal cordierite ceramics. The simultaneous growth of cordierite and spinel gives improved microstructure at much lower temperature and show much superior properties combinations such as low shrinkage, low thermal expansion, low porosity, high bending strength, high compressive strength etc.
The characteristic of the raw materials used in the examples are given below

(Table Removed)
The following examples are given by way of illustration of the present invention and should not be construed to limit the scope of the present invention.
Example -1
1 kg of Garnet beach sand is wet ground for 12 hours. 1kg of Clay is ground so that all the materials become fine powder. 1 kg of Talc is also ground to break the lumps to fine powder. 500 g of fine garnet sand and 300 g of talc and 20Cg clay powders were dry mixed for 4 hours. The binding agent molasses was added to the batch, mixed and kept for 24 hours for ageing, finally pressed to desired shapes. The samples were dried at 110°C and fired in an electric furnace at a temperature of 1200°C for 2 hours.
Example - 2
1 kg of Garnet beach sand is wet ground for 15 hours. 1kg of Clay is ground so that all the materials become fine powder. 1 kg of Talc is also ground to break the lumps to fine powder. 550 g of fine garnet sand and 200 g of talc and 250g clay powders were dry mixed for 5 hours. The binding agent polyvinyl alcohol was added to the batch, mixed and kept for 24 hours for ageing, finally pressed to desired shapes. The samples were dried at 110°C and fired in an electric furnace at a temperature of 1100°C for 1 hours.
Example - 3
1 kg of Garnet beach sand is wet ground for 20 hours. 1 kg of Clay is ground so that all the materials become fine powder. 1 kg of Talc is also ground to break the lumps to fine powder. 550 g of fine garnet sand and 200 g of talc and 250g clay powders were dry mixed for 4 hours. The binding agent polyvinyl alcohol was added to the batch, mixed and kept for 20 hours for ageing, finally pressed to desired shapes. The samples were dried at 110°C and fired in an electric furnace at a temperature of 1100°C for 3 hours.
Example - 4
1 kg of Garnet beach sand is wet ground for 25 hours. 1 kg of Clay is ground so that all the materials become fine powder. 1 kg of Talc is also ground to break the lumps to fine powder. 500 g of fine garnet sand and 200 g of talc, 250g clay and 50g titanium oxide powder were dry mixed for 4
hours. The binding agent molasses was added to the batch, mixed and kept for 24 hours for ageing, finally pressed to desired shapes. The samples were dried at 110°C and fired in an electric furnace at a temperature of 1200°C for 1 hours.
Example - 5
1 kg of Garnet beach sand is wet ground for 25 hours. 1 kg of Clay is ground so that all the materials become fine powder. 1 kg of Talc is also ground to break the lumps to fine powder. 550 g of fine garnet sand and 150 g of talc, 2COg clay and 100g titanium oxide powder were dry mixed for 5 hours. The binding agent molasses was added to the batch, mixed and kept for 24 hours for ageing, finally pressed to desired shapes. The samples were dried at 110°C and fired in an electric furnace at a temperature of 1200°Cfor1 hours.
Example -6
1 kg of Garnet beach sand is wet ground for 30 hours. 1 kg of Clay is ground so that all the materials become fine powder. 1 kg of Talc is also ground to break the lumps to fine powder. 600 g of fine garnet sand and 200 g of talc and 200g clay powders were dry mixed for 4 hours. The binding agent polyvinyl alcohol was added to the batch, mixed and kept for 24 hours for ageing, finally pressed to desired shapes. The samples were dried at 110°C and fired in an electric furnace at a temperature of 1100°C for 2 hours.
Example - 7
1 kg of Garnet beach sand is wet ground for 30 hours. 1 kg of Clay is ground so that ail the materials become fine powder. 1 kg of Talc is also ground to break the lumps to fine powder. 600 g of fine garnet sand and 200 g of talc and 200g clay powders were dry mixed for 5 hours. The binding agent molasses was added to the batch, mixed and kept for 24 hours for ageing, finally pressed to desired shapes. The samples were dried at 110°C and fired in an electric furnace at a temperature of 1100°C for 3 hours.
Example -8
1 kg of Garnet beach sand is wet ground for 35 hours. 1 kg of Clay is ground so that all the materials become fine powder. 1 kg of Talc is also ground to break the lumps to fine powder. 600 g of fine garnet sand and 150 g of talc, 200 g clay and 100 g zirconium oxide powder were dry mixed for 4 hours. The binding agent was added to the batch, mixed and kept for 20 hours for ageing, finally pressed to desired shapes. The samples were dried at 120°C and fired in an electric furnace at a temperature of 1200°C for 1 hours.
Example -9
1 kg of Garnet beach sand is wet ground for 35 hours. 1 kg of Clay is ground so that all the materials become fine powder. 1 kg of Talc is also ground to break the lumps to fine powder. 600 g of fine garnet sand and 150 g of talc, 200 g clay and 100 g titanium oxide powder were dry mixed for 5 hours. The binding agent was added to the batch, mixed and kept for
24 hours for ageing, finally pressed to desired shapes. The samples were dried at 110°C and fired in an electric furnace at a temperature of 1200°C for 2 hours.
Example - 10
1 kg of Garnet beach sand is wet ground for 35 hours. 1 kg of Clay is ground so that all the materials become fine powder. 1 kg of Talc is also ground to break the lumps to fine powder. 600 g of fine garnet sand and 200 g of talc, 100 g clay and 100 g zirconium oxide pov/ders were dry mixed for 5 hours. The binding agent polyvinyl alcohol was added to the batch, mixed and kept for 24 hours for ageing, finally pressed to desired shapes. The samples were dried at 110°C and fired in an electric furnace at a temperature of 1200°C for 1 hours. The properties of new Cordierite-Spinel composites are given below :

(Table Removed)
The main advantages of the present invention are :
1. Incorporation of new phases combinations improve the mechanical and
other properties of the product.
2. Lower the sintering temperature.
3. Simplify the manufacturing process.
4. Wide usability range.
5. Lower the cost of product.



We Claim:
1. A process for making new Cordierite-Spinel composites using a
novel synergistic composition comprising 50 - 60 wt% Garnet
sand, 15-25 wt% Talc, 10-20 wt% Clay, 0-10 wt% Nucleating
agents which comprises grinding of garnet sand of the kind such as
herein described , for a period in the range of 12 - 35 hours and
sieving with 300 BS mesh size, drying the said ground garnet sand,
proportioning and thorough mixing of the ground garnet sand with
talc, clay and nucleating agents such as herein described , for 4-5
hours, sieving through 100 mesh BS , mixing the resultant with a
binding agent as defined herein, granulating and ageing for 20-24
hours after granulation, compacting the powder by conventional
methods used in ceramic fabrication, drying at the unfired
compacts at 110° -120°C followed by firing at a temperature in the
range of 1100°-1200°C for a period in the range of 1 to 3 hours to
get the new Cordierite-Spinel composites
2. A process as claimed in claims 1 wherein the nucleating agent used
is selected from Titanium oxide, Zirconium oxide.
3. A process as claimed in claims 1 wherein binding agent used is
selected from polyvinyl alcohol, molasses.
4. A process for making new Cordierite-Spinel composites using a novel synergistic composition substantially as herein described with reference to the examples.

Documents:

1126-del-1999-abstract.pdf

1126-del-1999-claims.pdf

1126-del-1999-correspondence-others.pdf

1126-del-1999-correspondence-po.pdf

1126-del-1999-description (complete).pdf

1126-del-1999-form-1.pdf

1126-del-1999-form-19.pdf

1126-del-1999-form-2.pdf

1126-del-1999-form-3.pdf


Patent Number 215664
Indian Patent Application Number 1126/DEL/1999
PG Journal Number 12/2008
Publication Date 21-Mar-2008
Grant Date 29-Feb-2008
Date of Filing 19-Aug-1999
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI-110001, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 MALABIKA CHAUDHURI CENTRAL GLASS & CERAMIC RESEARCH INSTITUTE, CALCUTTA 700 032, INDIA.
2 DINESH KUMAR DAS CENTRAL GLASS & CERAMIC RESEARCH INSTITUTE, CALCUTTA 700 032, INDIA.
3 NAR SINGH CENTRAL GLASS & CERAMIC RESEARCH INSTITUTE, CALCUTTA 700 032, INDIA.
4 GAUTAM BANERJEE CENTRAL GLASS & CERAMIC RESEARCH INSTITUTE, CALCUTTA 700 032, INDIA.
PCT International Classification Number C04B 35/195
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA