FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules  2005

COMPLETE SPECIFICATION
(SEE SECTION 10 AND RULE 13)

TITLE OF THE INVENTION

“VITRIFICATION OF SUPER ABRASIVE ARTICLES BY MICROWAVE ENERGY”
APPLICANTS:

Name : Wendt (India) Limited

Nationality : Indian

Address : 69/70 Sipcot Industrial complex  Hosur 635
126 Tamil Nadu India

The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed:-

TECHNICAL FIELD
[001] The embodiments of this invention relate to a ceramic bonded vitrified super abrasive product and more particularly but not exclusively the embodiments of this invention relate to hardening of the bond that is carried out by subjecting the product matrix to micro wave radiation. The curing temp fixed at 750oC to 820oC and the cycle of curing is also within 5Hrs to 6Hrs by Microwave cure process.

BACKGROUND
[002] The process of making vitrified super abrasive article is a known art. However  there is a need in the vitrified super-abrasive article state-of-the-art to reduce the energy consumed. Further  there is a need to achieve a cost reduction together on the overall procedure of manufacturing.
[003] Further  there is a need in the method of manufacturing a ceramic bonded vitrified super abrasive article that requires lesser volume of susceptor material.

OBJECT OF INVENTION
[004] The principal object of the invention is to provide a cost effective method of making a vitrified super abrasive article.
[005] Another object of the invention is to develop a method of manufacturing a ceramic bonded vitrified super abrasive product which requires lesser volume of susceptor material.

SUMMARY OF INVENTION
[006] In view of the foregoing  an embodiment herein provides an abrasive body  more particularly the embodiment of the invention relates to a vitrified super abrasive product  wherein the addition of chemicals and an extra super abrasive powder viz silicon carbide as partial suceptor as well as filler and Zn+ in the matrix to help to prevent oxidation of super abrasive diamond at a temperature of 800oC and more. Further  the setting of the super abrasive mass has effectively carried out in a microwave system at a very low temp of 750oC – 800oC in a specific time table of 4-7 Hrs  more precisely within 5-6 Hrs. The microwave facility is outsourced  custom built similar to conventional facility but the heating is by absorption of microwave by the body and heating up by itself instead of heat radiation transmitting from outer to inner core by conduction. The microwave cured mass confirms to specifications and have stable geometry.

DETAILED DESCRIPTION OF EMBODIMENTS
[007] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly  the examples should not be construed as limiting the scope of the embodiments herein.
[008] The embodiments herein disclose an abrasive product  more particularly a ceramic bonded vitrified super abrasive product and a method of manufacturing the ceramic bonded vitrified super abrasive product.
[009] The presence of various mineral oxides in the form of alkaline borosilicate ceramic bond known as frits in which the alkaline content is within 4% to 7% by weight  the boron content is 10% to 15% by weight. An external addition of 3% to 5% by weight of lithium carbonate in the formulation along with 5% by weight of Zinc oxide and 3% by weight of cuprous oxide facilitates low temperature curing  setting and prevents oxidation of diamond grits. The combination of the above three mineral oxides and carbonate imparts more strength to the bond and facilitates faster setting of the mass in a low temperature vitrification. The art of manufacturing a grinding wheel as per the general practice of the skills are adopted in the process to roll out a grinding wheel wherein the bond occupies a portion of the mass in the range of 15% to 30% by volume. A technique considered to use wax emulsion as a cold setting binder in the preliminary stage exhibit good binding character as well a mold releasing agent. The wax emulsion contains 55% to 65% of water on the overall 8% to 10% by volume of the wax. The grain selection is based on diamond and other substitute grits and filler grit more precisely SiC (green). The specific substitute grits are Sol-Gel or its other forms of derivatives. The filler grit is an essential part of the curing system  more accurately it is defined as susceptor in Microwave curing. The bond is the frit chemically known as an alkaline borosilicate body. The process of fritting is the well known art. The contents of the frit are feldspar  china clay  quartz minerals and boric acid or borax  soda ash  potassium carbonate and calcium carbonate (CaC03) chemicals. All the materials are mixed and ball milled for about 6 hours and then sieved thro a proper mesh of 120ASTM standards. The Homogenous mix is then transferred to a frit making kiln. The charged mix is heated slowly to temp of 1230oC in order to completely melt the mass to a free flowing viscosity level like that of water. The melt is then transferred to a tub containing chilled water  where the melt crystallizes and turn into a glassy mass of greenish blue in color. The mass is then dried and powdered to 325mesh size by using a ball mill. Further  the mass as an embodiment of super abrasive article is subjected to a curing cycle by allowing vitrification to take place in a microwave oven where in the frequency of the oven is set to 2.45 GHz which is the fixed frequency for industrial applications.
[0010] The procedure adopted in the art of making a grinding wheel is an established skill  in the matter of formulation and conventional in wheel forming technique. In an embodiment of the present invention  adding Zinc oxide as filler in order to prevent grit oxidation and improving the wettability is an added phenomenon. Another projection of silicon carbide of 320mesh and above as a filler in the mix matrix enhances the microwave function.
[0011] Both add-ons have definite function as filler and as a process aid. The addition of Zinc oxide of 320mesh is preferred within the limit of 4% to 7% in weight. The material namely silicon carbide is a super abrasive grain  the silicon carbide has a dual function as effective filler in grinding as well as a good susceptor at elevated temperature. This will reduce the susceptor volume externally placed or covered of the volume. The volume of susceptor  normally recommended is three times the mass of the product. But according to the practice experience the presence of external susceptor level can be one half of the calculated quantity.
Description of the work
[0012] The embodiment under consideration is a grinding wheel in which super abrasive particles like diamond and CBN are the principle materials. An essential compound is the bond which is of frit powder  made from clays and chemicals. The compositions of the constituent are Feldspar  Quartz  China clay  Borax or Boric acid  Sodium Carbonate  Potassium Carbonate and Calcium Carbonate by weight percentage fused to get the frit.
[0013] In addition to the frit the other add-ons are cuprous oxide  Lithium Carbonate and Zinc oxide fine powders (#325 mesh). The addition of the above said powders are collectively 14% by weight to frit powder. Further  minimum 5% by weight is Zinc oxide. The presence of Lithium Carbonate is between 3% and 7%  and precisely it is 3% in that 14%. Addition of Cupperic oxide is 2-5%  preferably 2%.
[0014] The mix matrix in the final form is 50% to 60% by volume of abrasive grit  more precisely by 50% in volume. In one embodiment  abrasive grit is a super abrasive grit. The substitute grit is 15% to 20% of volume exactly 18.5 % in volume. Microwave Energy Filler is 10% to 15% in volume. The bond occupies 12% to 15% in volume  more precisely 13 % in volume. Further  5 volume percentage is occupied by temporary binders like 40% wax emulsion and powdered phenolic resin which goes off from the system as volatiles leaving a porosity of 2 % maximum.
[0015] The process has carried out in the form of making a PCD grinding wheel of 150X20/10X110 which then cured by microwave. The cured wheel is then fixed on to aluminium blank and dried out in a machine.
[0016] The making of the wheel is in line with the making of conventional practices hitherto followed by abrasive industry. A known quantity of super abrasive mix is filled into the cavity of a die and is subjected to compaction pressure. The wheel is extracted from the die and is subjected to drying at 120oC for 2Hrs to 3Hrs. However  the temperature and time period may vary from volume to volume of super abrasive mix. However  the maximum temperature is fixed as 120oC ± 5oC.
[0017] Further  the design of microwave is similar to a conventional oven for a look. However  the inner side of the microwave is lined with fiber board of ceramics to withstand high temperature and to insulate the outer body. The oven is fitted with 2X1.5 Kw microwave power source.
[0018] The dried body is then placed inside the oven. The plate carrying the wheel is a cordierite batt. The wheel is placed in the batt with quartz 24/60 grit as separator in between wheel and batt. The temp cycle followed during curing. The cycle is 5Hrs  starting from 95o C to 800o C with ramp and hold at 500oC  600oC  700oC and 800oC. The ramp is between 10minutes to 20minutes time and the hold is within 30-40 minutes in each stage.
[0019] The process of cooling is natural and the wheels taken out and tested for vitrification  for bell sound by grind sonic testing to confirm quality.
Thus the process has been established and the products evaluated. The results are compared with the conventional cure process. The microwave energy has enabled to rollout more similar product equivalent to one manufactured through conventional method. Hence we are able to conclude that though process parameters are different the end results are conforming to standards.
The addition of silicon carbide to the mix matrix has performed well as a susceptor and filler and this helped for a faster cure by microwave and additionally for better performance
From tests the grinding embodiments of this nature is well suited for microwave energy curing.
[0020] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can  by applying current knowledge  readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept  and  therefore  such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore  while the embodiments herein have been described in terms of preferred embodiments  those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims
We Claim 
1. A ceramic material composition  wherein major portion of said ceramic material composition includes mineral oxides incorporated as bond in an abrasive body.
2. The ceramic material composition as claimed in claim 1  wherein said bond is in the form of firt  said firt includes oxides of silicon  aluminium and boron as major constituents along with three alkali oxides of sodium  potassium and lithium.
3. The ceramic material composition as claimed in claim 1  wherein said bond further includes zinc oxide.
4. The ceramic material composition as claimed in claim 1  wherein said bond further includes cuprous oxide to enhance strength of bond.
5. The ceramic material composition as claimed in claim 2  wherein said boron constitutes 10% to 15% weight of the bond.
6. The ceramic material composition as claimed in claim 2  wherein said alkali oxides constitute 5% to 10% weight of the bond.
7. The ceramic material composition as claimed in claim 1  wherein said bond further includes a wax solution.
8. The ceramic material composition as claimed in claim 7  wherein said wax solution constitutes 40% by weight wax content
9. An abrasive body comprising:
abrasive particles; and
a ceramic bond for binding said abrasive particles 
wherein
said ceramic bond includes a ceramic material composition having mineral oxides.
10. The abrasive body as claimed in claim 9  wherein said abrasive particles is diamond grains.
11. The abrasive body as claimed in claim 10  wherein said abrasive particles includes silicon carbide grains as substitute grains and filler material.
12. The abrasive body as claimed in claim 10  wherein said abrasive particles further includes atleast one of sol-gel abrasive grain and krystolax abrasive grain.
13. The abrasive body as claimed in claim 9  wherein said abrasive body is formed by curing process.

14. The abrasive body as claimed in claim 13  wherein said curing process is performed by microwave technique.

Dated: 26th December 2011 Signature:
Dr Kalyan Chakravarthy
(Patent Agent)

ABSTRACT
An abrasive article consisting an abrasive  more particularly super abrasive compacted with powdered ceramic bond or bonds thereof subjected to hardening process by dielectric heating to form a grinding embodiment in which certain amount of silicon carbide grain included as an accelerator to enhance the heating.