Polishing tool and a composition for producing said tool

Abstract

The invention can be used in various industries for machining miniature and large sized articles made of sapphire, quartz, ceramic, semiconductor and other hard-to-treat materials, including two-side machined pieces without preglueing. The inventive tool comprises a chuck provided with abrasive elements in the form of pellets fixed thereto. Abrasive filler is arranged between said elements. The density and abrasive grit of said abrasive filler range correspondingly from 0.2 to 0.8 and from 0.01 to 0.5 with respect to the density and abrasive grit of the elements. The inventive composition consists of epoxy resin, diamond-containing abrasive, a hardener, a filler and polyhydride siloxane. The polyhydride siloxane is used in order to form pores when reacting with the hardener during the production of the tool. Said invention makes it possible to produce the tool having a high cutting performance which ensures a high surface finish.

Description

[0001] The invention pertains to the diamond-abrasive machining of various materials as well as to manufacture of fixed abrasive tools.

[0002] The invention can be used in various industries for machining sapphire, quartz, ceramics, glass articles, semiconducting materials and various materials. It may be efficiently used when processing miniature articles and thin large-sized articles, including double-sided machining without preparatory gluing of articles being processed.

[0003] Polishing tools for articles machining, which contain chucks with abrasive units in the form of pellets attached thereto (1), are well-known. The disadvantage of such polishing tools is that's difficult and often impossible to machine thin large-sized articles (having thickness ratio h/D≦1/50) without preglueing of articles to a substrate. This could be explained in the following way. Since fixed abrasive tool is able to work in self-sharpening mode only under sufficiently high specific pressure, the compactness of chuck surface filling with abrasive pellets should be minimal. However such chuck filling with abrasive pellets is unacceptable when machining small-sized articles, as they simply fall through between the pellets. On the other hand, when machining thin large-size articles with thickness ratio h/D≦1/50, low compactness of chuck filling with pellets results in deformation of thin bearing separators with processed articles, being attached to their sockets, under working load in course of operation. As a result of such deformation separators and parts hit against pellets located far from each other, deteriorate themselves as well as damage the polishing tool. In order to exclude that, it is often resorted to filling the space between pellets with various filling agents, for example, the space between pellets is filled with epoxy resin. However, that results in greasing of the tool and in impossibility of its operation.

[0004] Polishing tool, being in technical terms the most similar to the proposed invented tool, is a tool containing chuck with abrasive units attached thereto. The space between abrasive units is filled with filler containing abrasive (2). In such polishing tool the abrasive units in the form of flat plates are attached endways to the chuck with infill ratio 0.05-0.15, and the space between the plates is filled with epoxy resin. At that, the epoxy resin contains abrasive having grit equal to the grit of flat abrasive plates or 1-2 numbers lower, and the quantity of abrasive makes 10-15% from the epoxy resin volume.

[0005] Such polishing tool may be used in operations of preparatory roughing or some materials primary polishing, which allows very high specific pressure during machining.

[0006] The disadvantage of such a polishing tool is in low effectiveness of polishing due to epoxy resin presence between abrasive plates. This is explained by the following reasons. In the first place, owing to sharp increase of total area of the polishing tool working surface, the specific pressure to cutting tool decreases scores of times, for instance, in case of infill ratio range stated above the specific pressure decreases from 7 to 20 times. Therefore it is necessary to increase total polishing tool and machined articles loading heavily. But that automatically results in deformation of articles machined and as a consequence in degradation of machining geometries. During machining of miniature articles they often fail for the reason of overloading in the region of processing. In the second place, as is well known the epoxy resin brings to greasing of tool. Presence of abrasive in the epoxy resin is not able to provide operation of polishing tool in self-sharpening mode in full measure, as the factor of abrasive plates cutting surfaces greasing noticeably predominates the factor of opening by means of abrasive released as a result of filler wear.

[0007] The composition for polishing tools including epoxy resin, hardener, abrasive, filler and blowing agent as a sticker is well-known (3). Polishing tool made of the said composition may be used efficiently enough for rough and semifinish glass polishing.

[0008] However, such tools are of little use in case of high-strength hard-to-treat materials processing, and may not be used in operations of the final as well as preparatory polishing.

[0009] Composition, being the most similar to the proposed invented one, is the composition designated for manufacture of abrasive tools containing sticker using epoxy resin with hardener, diamond-containing abrasive and filler (2).

[0010] The disadvantage of such composition is that tools manufactured on its basis may work only under sufficiently high specific pressure, and consequently, the infill ratio should not be high. The same, as it was stated above, results in impossibility of operation of such tools during machining of miniature or small-sized articles.

[0011] The technical aim is to create polishing tools and composition for their manufacture, which are able to provide sharp increase of productivity and quality of such intractable materials as sapphire, quartz, ceramics, semiconducting materials while machining, effective use of such tools for machining miniature and small-sized articles with thickness ratio h/D≦1/50, which may be machined with utter difficulty with traditional polishing tools.

[0012] The problem could be solved owing to the fact that the polishing tool, which contains chuck with abrasive units attached thereto, filled with filler with abrasive in the space between such units, is characterized by abrasive units of pellets form, filler density makes 0.2-0.8 from the density of abrasive pellets, and the grit of the filler abrasive makes 0.01-0.5 from the grit of abrasive pellets material. The filler in the space between abrasive pellets may be realized in the form of adjuvant abrasive pellets attached to the surface of the chuck. The ratio of the basic and adjuvant abrasive pellets is preferably chosen in the range from 1:6 to 4:1. The filler may also be placed in the whole space between abrasive pellets, and penepoxide, added with composition of abrasive with fine powder of aminoplast or/and phenoplast, is used as such filler, at that proportion of abrasive and aminoplast or/and phenoplast in the filler makes correspondingly 15-30% and 10-40% from the penepoxide mass.

[0013] In this case the filler density may be 0.05-0.5 from the density of the abrasive pellets.

[0014] The problem is solved owing to the fact that the composition for manufacture of the polishing tool containing epoxy resin, diamond-containing abrasive, hardener and filler is characterized by polyhydride siloxane in the following ratio (relative mass portions):

Epoxy resin                 100
Hardener                    5.0-10
Diamond-containing abrasive 0.1≧60
Filler                      5.0-80
Polyhydride siloxane        0.2-5.0

[0015] The composition may additionally contain formic acid as a functional additive in amount of 1.0-10.0 relative mass portions.

[0016] The composition of polirit based on not less than 70% of cerium dioxide, microbeads made of silicon dioxide sized from 10 to 100 nm., graphite powder and fine-dyspersated metal powder may be used as a filler.

[0017] The composition of cerium dioxide with aminoplast, being thermosetting pressing mass, based on urea-, carbamide-, melamine- and/or carbamidemelamineformaldehyde resin and/or phenoplast, being thermosetting pressing mass, based on formaldehyde resin, may be used as a filler, at that cerium dioxide and aminoplast and/or phenoplast in the composition are in the ratio of 1:(0.1-10).

[0018] The composition of diamond dust and auxiliary abrasive, being corundum or silicon carbide or boron carbide or boron nitride or their composition may be preferably used as the abrasive, at that the diamond dust and the auxiliary abrasive are in the ratio of (0.01-10):(50-0.5) relative mass portions.

[0019] The invention is explained by the Figure, where:

[0020] FIG. 1 displays a polishing tool with filler in the form of auxiliary pellets:

[0021] FIG. 2 displays a polishing tool with filler in the whole space between abrasive units.

[0022] The polishing tool contains a chuck 1 with alternating basic abrasive pellets 2 and auxiliary abrasive pellets 3 attached thereto. In such polishing tool example (FIG. 1) the quantity of basic and auxiliary abrasive pellets are in the equal ratio, i.e. 1:1.

[0023] FIG. 2 displays the polishing tool containing a chuck 1 with abrasive pellets 2, attached thereto, with filler 4 flooding the space between them.

[0024] The polishing tool may be used in operations of one-sided and double-sided machining of flat as well as other surfaces.

[0025] In the process of miniature articles machining as well as machining of flat surfaces of thin articles having thickness ratio h/D≦1/50 by means of fixed diamond-abrasive tool the following contradictions occur. On the one hand, it is necessary to maximize infill of the chuck surface with abrasive pellets. On the other hand, such infill results in decrease of the specific pressure of the tool to machined article, such decrease results in greasing of the polishing tool and in decrease of material takeoff. This problem is solved by utilizing auxiliary pellets or solid filler having density and solidity much lower than ones of basic abrasive pellets. The auxiliary pellets are manufactured high-porous with interstice content in the ratio of 20-80%. In the event that the density of the auxiliary pellets mass is lower than 0.2 from the density of the basic pellets, i.e. in the event that gas phase content in the pellets mass exceeds 80%, extremely high wear and intensive flaking of separate large-sized articles of pellets occur, that results in formation of scratches on the surface being machined. The utilization of auxiliary pellets with mass density higher than 0.8 from mass density of the basic abrasive pellets does not provide appreciable positive effect.

[0026] Wear of the auxiliary pellets takes place under the lower specific pressure. Therefore, even in the event that infill of the chuck surface exceeds 50%, that does not result in sharp decrease of the specific pressure and results in greasing of the tool.

[0027] The usage of finer (from 2 to 100 times) abrasive in the mass of filler of the abrasive pellets provides effect of additional coercive opening of the working surface of the basic pellets. This makes it possible to use those pellets under much lower pressure. That means that some decrease of specific pressure to the basic abrasive pellets for the reason of high compactness of filling with auxiliary pellets is compensated by the effect of additional opening of the basic pellets by the finer abrasive of the auxiliary pellets or by the solid filler. Furthermore, the decrease of the specific pressure results in increase of machined surface forming precision, and the presence of additional abrasive in machined region provides reduction of roughness of surface being machined. It is necessary to note that in the filler mass it is inadmissible to use abrasive having grit of the basic cut higher than 0.5 from the abrasive grit of the basic abrasive pellets, as that results in notable deterioration of the surface roughness as well in formation of deep separate scratches on the surface of a article, being machined. And utilization of abrasive having grit lower than 0.01 from the basic abrasive pellets grit in the filler does not provide effect of opening of the polishing tool working surface For instance, in case of using of polishing tool containing basic abrasive pellets with diamond dust having graininess 100/80 mm., auxiliary pellets, using corundum as abrasive with grit 5 0, work efficiently.

[0028] The basic and auxiliary pellets quantity ratio is in a rather wide rage from 1:6 to 4:1. At that, time it is necessary to choose required ratio of the basic and auxiliary pellets in every individual case taking into account following factors. For example, in case of machining of such hard and intractable materials as sapphire, synthetic quartz, silicon carbide it is needed to use high specific pressure. Therefore, in such case the optimal ratio of the basic and auxiliary pellets quantity is from 1:1 to 1:4.

[0029] The ratio of the basic and auxiliary pellets quantity less than 1:6 should not be used in the process of the polishing tool manufacture, designated for machining of any material, as cutting ability of such a tool will be very low.

[0030] In case of manufacture of a polishing tool with filler, placed in the whole space between abrasive pellets, the base of such filler is foamed epoxy resin, being gas-filled material based on epoxy resin. This is hard material with closed cells structure. It is of high mechanical durability even at increased working temperatures. Taking also into account its high adhesive power in relation to the most of materials, it could be concluded that foamed epoxy resin with abrasive additives and other components may be ideal filler, flooding the space between abrasive pellets. The process of foaming and hardening of foamed epoxy resin is simple in technical terms. It allows controlling density of product gas-filled material in a very wide range.

[0031] The density of the foamed epoxy resin may be controlled subject to methods and modes of foaming in the range from 0.02 to 0.4 g/cm3. Besides, the compactness of the abrasive pellets, which may be used for manufacture of polishing tools, could be in the same wide range from several grams per cubic centimeter, for example, in case of diamond pellets on metal matrix, to several gram proportions per cubic centimeter in case of porous diamond pellets on organic matrix. Therefore, the density of the filler should be coordinated with density of the abrasive pellets.

[0032] For polishing tools with solid filler the range of filler density in relation to the density of the abrasive pellets could be somehow changed. The range of filler density, chosen for our polishing tool from 0.05 to 0.8 from the density of the abrasive pellets, is determined by the following conditions: the bottom limit of the filler density −0.05 from the density of the abrasive pellets makes it possible to machine materials under utterly low specific pressure, as such filler decreases the specific pressure to the working tool insignificantly. However, further extension of air interstice may result in flaking of large sized particles of the filler that results in scratches on materials being machined.

[0033] In the process of defining of optimal abrasive grit used in the filler it was unambiguously ascertained that utilization of equal abrasive grit pellets is inadmissible, as that results in increased wear of the tool, rough scratches occurrence and does not provide necessary surface roughness.

[0034] The utilization of fine-grained abrasive in the filler forming 0.01-0.5 from abrasive grit of the abrasive pellets provides the best results of polishing tools operation. In the first place, fine abrasive adheres well to thin walls of foamed epoxy resin cells, and as they wear it provides the effect of smooth opening of the abrasive pellets working surface.

[0035] The abrasive for the filler with grit 0.5 from the abrasive pellets grit may be used for rough polishing tools or for tools used in extremely hard conditions of operation. Even such abrasive grit in the filler results in notable worsening of surface roughness and in increased tool wear. The utilization of abrasive with grit less than 0.01 from the abrasive pellets grit does not provide effective opening of the polishing tool working surface.

[0036] As is was shown by pilot research, in the process of filler manufacture even for rough polishing tool, using abrasive pellets with abrasive grit not less than 100 micrometers, abrasive grit for the filler may be equal 10-20 micrometers.

[0037] The infusion of fine-dyspersated powders of aminoplast being thermosetting pressing mass, based on urea-, carbamide-, melamine- and/or carbamidemelamineformaldehyde resin and/or phenoplast, being thermosetting pressing mass, based on formaldehyde resin, in proportion of 10-40% from the foamed epoxy resin mass into such foamed epoxy resin in addition to the abrasive results in fortification of the filler and provides additional effect of tool opening. Besides that, this powder takes part in forming of the surface microrelief, and provides improvement of the surface roughness for one grade, when it wears and contacts surface being machined.

[0038] Considering the fact that in the process of the filler manufacture fine grit abrasive together with fine-dyspersated power of aminoplast and/or phenoplast, having huge total free surface, are used, the quantity of abrasive and aminoplast and/or phenoplast should not exceed 30% and 40% correspondingly from the mass of foamed epoxy resin. Otherwise unconnected abrasive clods may appear in the mass. Those lamps will flake in the process of the polishing tool operation and affect conditions of such tool operation.

[0039] The minimal quantities of abrasive and fine-dyspersated powder of aminoplast and/or phenoplast equal 15% and 10% correspondingly are defined by conditions of provision of abrasive pellets working surface opening by means of releasing particles of abrasive and powder.

[0040] For the purpose of settlement of the technical problem put by this invention, besides creation of above-mentioned polishing tool, it was necessary to create a composition for its manufacture. The composition for producing this polishing tool contains epoxy resin with hardener, for instance polyethylenepolyamine, as a sticker. Additional utilization of organosilicon liquid namely polyhydride siloxane in amount of 0.2-5 relative mass portions in respect of 100 relative mass portions of the epoxy resin, results in formation of gas-expanded material. The formation of interstices is the result of reaction of polyethylenepolyamine with polyhydride siloxane, resulting in effervescence of hydrogen forming bubbles in the mass. The mass foaming process has three stages: interstices formation, their expansion and stabilization. Depending on the quantity of polyhydride siloxane added to the mass as well as on modes of pore-formation and polymerization it is possible to control quantity and size of interstices in the product material in very wide range. The ambient air temperature, mass temperature and used moulds temperature affect the process of pore-formation very noticeably. Therefore, for the purpose of production of the mass for manufacture of a tool with predetermined properties it is necessary to perform the process in strictly controlled conditions using special forms and thermostats. The presence of gas phase in the mass favorably affects mechanical shockproof of the tool. It has higher dynamic shockproof characteristics owing to the shock-absorbing capacity of the gas-expanded material.

[0041] It should be kept in mind that in the process of porous abrasive pellets manufacture the mass density of such abrasive pellets affects their durability considerably. For example, in case of contraction of foamed abrasive pellet with mass density of 0.1 g./cm3 the durability makes about 4 kg-wt/cm2, and in case of pellet with density of 0.4 kg./cm3 the durability makes more than 80 kg-wt/cm2. Therefore in the process of porous abrasive pellets manufacture polyhydride siloxane in amount of more than 5 relative mass portions in respect of 100 relative mass portions of epoxy resin should not be used for the reason of low durability of the product pellets.

[0042] It is necessary to lay stress on a special role of free hydrogen emerging in the region of tool cutting when opening cells filled with hydrogen.

[0043] As is well known, the hydrogen is an ideal reducing agent. Interaction of hydrogen in the critical moment of its emission (“. . . in stade nascent . . . ”) with various materials often plays the decisive role. When machining metals the reducing ability of hydrogen prohibits from formation of oxidic hard-to-machine pellicles. In the process of silicon machining hydrogen, being reducing agent binding oxygen, prohibits formation of silicon dioxide in the contact region, and thus prevents growth of submicron fractures and microfissures in the monolith silicon mass. In the process of machining of SiO2 containing materials, for example, synthetic and fused quartz or various glass types, presence of hydrogen prevents formation of hardly destroyable silicic acid pellicle gel in the working zone. Such effect of hydrogen facilitates sharp decrease of specific pressure in the working region and, as a consequence, facilitates reduction of disrupted layer during materials machining.

[0044] There is one more positive effect of hydrogenous interstices being under overpressure. In the process of immediate pore opening microdestruction of the tool mass regions, adjacent to the emerged channel, occurs. That facilitates additional effect of the tool self-sharpening.

[0045] The effect of positive impact of free hydrogen in the region of diamond tool cutting increases presence of formic acid in the composition for the diamond tool. As is well known, when heated the formic acid decomposes with formation of hydrogen and carbonic acid. Therefore in the cutting zone, where the local temperature considerably exceeds the temperature of formic acid decomposition, the hydrogen emerges that intensifies and amplifies its reducing action to machined material. Besides, the formic acid, dissolving in aqueous solution of lubricating fluid, stimulates loosening and renovation of the diamond tool working surface.

[0046] A special role of the filler in the proposed composition for diamond tools should be noted.

[0047] In the known compositions cerium dioxide played the role of just an auxiliary abrasive. However the presence of cerium dioxide itself as filler or as “an auxiliary abrasive” results in the fact that diamond tools may work in the self-sharpening mode only under increased specific pressure. This concerns structure of cerium dioxide particles of platy structure. On the one hand, as they wear large-size particles of the filler, capable to scratch machined material, do not flake. On the other hand, the platy structure of cerium dioxide makes for tool greasing.

[0048] Therefore, the usage of the composition of polirit, based on not less than 70% of cerium dioxide, microbeads made of silicon dioxide, sized from 10 to 100 nanometers, graphite powder and fine-dyspersated metal powder in the composition for diamond tools as filler makes it possible to scientifically increase operating performance of the tools. That is determined by the following. The interchange of polirit plate-like particles, sized from 1 to 8 micrometers, and microbeads made of silicon dioxide, sized from 10 to 100 nanometers, makes microdestruction of polirit particles, that prohibits greasing of tools in the process of their operation. Such combination of the filler is especially important for manufacture of diamond tools with respect to finish and preparatory polishing using fine diamond dust sized less than 10 micrometers.

[0049] The inclusion of graphite powder, having platy structure, makes lubricating properties of the diamond tools much better. It is especially effective to use graphite powder in the filler composition in the process of diamond tool manufacture for the purpose of machining of such materials as high-strength ceramics, steel and other materials.

[0050] On the grounds of the fact that the basic components of the described composition for diamond tools are organic components with rather low thermal conductivity properties such fact involves difficulties in operation of the diamond tools under severe operation conditions, namely under high specific pressure and high processing speed. Therefore, for the reason of improvement of operating properties of the diamond tools fine-dyspersated metal powder is included into the filler composition. It provides intensification of heat removal from the working zone.

[0051] In another variant of composition the composition of cerium dioxide and aminoplast, being thermosetting pressing mass, based on urea-, carbamide-, melamine- and/or carbamidemelamineformaldehyde resin and/or phenoplast, being thermosetting pressing mass, based on formaldehyde resin, in amount of 5-80 relative mass portions, is used. At that, cerium dioxide and aminoplast and/or phenoplast are in ratio of 1:(0.1-10). The separate usage of cerium dioxide and aminoplast or phenoplast does not meet the requirements. The usage of only cerium dioxide as filler in the mass for abrasive tool manufacture results in worsening of cutting ability of the tool and its inclination for greasing. Besides that, for the reason of inclination of cerium dioxide aggregation there are clods appearing in the mass for abrasive tool manufacture. Those clods embarrass operating properties of the tool. The usage of only aminoplast or phenoplast as filler results in excessively high solidity of the abrasive pellets that requires increased specific pressure in the process of the tool operation. The best results were achieved, when composition of cerium dioxide and aminoplast and/or phenoplast in amount of 5-80 relative mass portions with their proportion in the composition equal 1:(0.1-10) was used as filler for manufacture of the abrasive tool. Owing to usage of the said composition as filler it was a success to considerably improve machining quality as well as productivity of polishing tools due to reducing of specific pressure in working zone. In the process of usage of the abovementioned composition formation of conglomerates, when mixing components, was completely excluded.

[0052] The usage of the composition of diamond dust and auxiliary abrasive in the mass for abrasive tool manufacture results in significant improvement of machining performance of tools. Corundum, silicon carbide, boron carbide, boron nitride or their composition may be used as such auxiliary abrasive. At that, depending on current task the ratio of diamond dust and auxiliary abrasive in total mass may be varied within the range (0.01-10):(50-0.5) relative mass portions. Such wide range makes it possible to obtain a wide variety of polishing tools for various applications. In the process of auxiliary abrasive pellets manufacture it is necessary to use minimal quantity of diamond dust, but maximal quantity of auxiliary abrasive. And conversely, in the process of basic abrasive pellets manufacture it is necessary to use mainly diamond dust with insignificant addition of auxiliary abrasive. As it was stated above, corundum, silicon carbide, boron carbide, boron nitride or their composition may be used as such auxiliary abrasive. At that, the harder machined material the more durable auxiliary abrasive should be.

[0053] The diamond tool in the form of pellets is manufactured in the following way. The components are blended into epoxy resin under thorough agitation in the following order: diamond dust, filler, formic acid, polyhydride siloxane and hardener. After that the mass is agitated till homogeneous consistence is achieved. The mass should be matured within 1-15 minutes depending on the composition and the volumetric content of polyhydride siloxane. After that, moulds are filled with foamed mass strictly dosed. The mass is matured within 12-24 hours, after that the diamond pellets are withdrawn from moulds. After that the product diamond pellets are heat-treated at 60-110° C. during 0.5-4 hours.

[0054] Diamond tools manufactured with usage of diamond pellets with the described composition were tested in laboratory and industrial environment on a double-sided processing machine of SDP-100 model in machining of various materials.

[0055] Let us cite data on results of testing of a diamond tool, manufactured on the basis of the composition claimed, in the process of machining of silicon wafers 100 mm in diameter. The polishing tools represent metal chucks 500 mm in outer diameter and 287 mm in interior diameter. Diamond pellets 16 mm in diameter and 6 mm in height are attached to the chucks by means of two-part adhesive, 210 units per each chuck. The diamond pellets were manufactured in compliance with the invention proposed at the blending ratio, indicated in Table 1.

TABLE 1
Components	Components content, relative mass portions
Numbers of instances	1	2	3	4	5	6	7	8	9	10
Epoxy resin	100	100	100	100	100	100	100	100	100	100
Hardener	7	7	7	7	6,5	6,5	10	5	6,5	6,5
Diamond powder	0,1	30	5	5	3	3	5	5	3	3
Filler
Optical Polirit	20	20	20	50	10	5	70	30	30	30
Microbeads SiO2	—	—	5	10	1,5	—	5	5	—	—
Graphite powder	2	2	5	5	1	—	3	—	5	—
Copper powder	2	—	—	5	2	—	2	—	—	—
Formic acid	2	2	—	—	5	10	2	1	2	2
Polyhydride siloxane	0,4	4	2	2	2	3	3	3	1	1
Machining Parameters
Numbers of instances	1	2	3	4	5	6	7	8	9	10
Area efficiency, micrometers/min	0,3	1,5	2	2,2	1,5	0,8	0,9	1	1,4	1,2
Surface roughness, Ra, nanometers	25	20	15	7	10	21	18	22	24	22
Faulted layer depth, micrometers	3	2	2	0,5	0,5	1,5	1,8	1,7	1,4	1,6

[0056] The quantity of polyhydride siloxane in our composition for diamond tool is chosen in the range from 0.4 to 4 relative mass portions with respect to 100 relative mass portions of epoxy resin. When using less than 0.4 relative mass portions of the said foaming agent, very insignificant pore-formation occurs. That does not provide required effect, when using diamond tool of this composition. At that, it should be avoided to use more than 4 relative mass portions of polyhydride siloxane in the process of porous diamond tool manufacture, as this will result in reduction of diamond tool strength and in sharp reduction of its durability.

[0057] The optimal range of formic acid quantity in this composition makes from 1 to 10 relative mass portions. The bottom of formic acid quantity is conditioned by minimal quality of hydrogen emission, which still exerts positive influence upon machined material in the process of its machining. In case of using more than 10 relative mass portions of formic acid, it partially reacts with hardener that results in incomplete polymerization and, as a consequence, in nonoperability of the diamond tool manufactured.

[0058] The testing was performed under following machining modes:

Chuck rotation speed, revos      35
Specific pressure, kilogram-force/cm3 0.03

[0059] The comparative results of testing of described diamond tool on the basis of claimed composition (#1) and on the basis of known composition (#2) in the process of silicon wafers machining are indicated below:

Machining Parameter/Number of
Composition	#1	#2
Area efficiency, micrometers/min	1.5	0.2*
Surface roughness, Ra, nanometers	≦0.01	0.12
Faulted layer depth, micrometers	0.5	5
Note:
*In the process of diamond tool testing based on the known composition, it was noticed that the tool becomes greasy rapidly and deep scratches appear that was absolutely absent when testing diamond tool based on the claimed composition.

[0060] Fixed abrasive pellets using the composition, described in calaims 4 and 5 of the subject of invention, are manufactured in the following way. The composition of diamond dust and auxiliary abrasive is prepared and thoroughly agitated separately. The composition of cerium dioxide and and aminoplast and/or phenoplast is prepared separately.

[0061] At the room temperature components are blended into epoxy resin under thorough agitation in the following order: the composition of diamond dust and auxiliary abrasive, composition of cerium dioxide and aminoplast and/or phenoplast, polyhydride siloxane and polyethylenepolyamine. The mass is agitated till homogeneous consistence is achieved and is filled into moulds strictly dosed by means of batcher. The mass in moulds is matured till the pore-formation process ending. After mass in moulds maturing at the room temperature within not less than 12 hours, the abrasive pellets are withdrawn from moulds ad heat-treated at 70-90 degrees Celsius during 0.5-4 hours.

[0062] Polishing tools manufactured with usage of this composition were tested in laboratory and industrial environment on a double-sided processing machine of SDP-100 model in machining of various materials. Let us cite data on results of testing of the described tool, manufactured on the basis of the composition claimed in the process of machining of sapphire disks 100 mm in diameter. The polishing tools represent aluminium chucks 500 mm in outer diameter and 287 mm in interior diameter. Basic and auxiliary pellets 16 mm in diameter and 6 mm in height are attached to the chucks by means of two-part adhesive, 420 units per each chuck. Diamond pellets on organic binding material of PT100P1 type, manufactured by “OOO Precisionnie Protsessi”) (Moscow), were used as basic abrasive pellets. The diamond cut of those pellets is 100/80 micrometers. Abrasive pellets, manufactured in conformity with the invention with components ratio indicated in Table 2, were used as auxiliary abrasive pellets.

TABLE 2
Components	Components content, relative mass portions
Numbers of instances	1	2	3	4	5	6	7	8	9	10
Epoxy resin	100	100	100	100	100	100	100	100	100	100
Hardener	7	7	7	7	5	6,5	10	7	6,5	6,5
Diamond containing abrasive	0,1	60	25	37	30	61	15	55	12	12
Including: Diamond powder	0,1	—	2	2	3	1	5	5	2	2
Corundum	—	60	20	20	—	20	10	25	10	10
Silicon carbide	—	—	3	15	15	20	—	25	—	—
Boron carbide	—	—	—	—	12	10	—	—	—	—
Boron nitride	—	—	—	—	—	10	—	—	—	—
Filler
Optical Polirit	20	1	20	20	—	4,5	10	10	—	—
Aminoplast	20	10	20	20	40	0,5	40	5	25	—
Phenoplast	10	—	—	—	20	—	—	15	25	45
Formic acid	—	—	—	—	—	—	—	1	—	2
Polyhydride siloxane	0,2	3	4	4	3	5	3	3	2	2
Tool Parameters
Numbers of instances	1	2	3	4	5	6	7	8	9	10
Abrasive units density, g/cm3	1,5	1,5	1,5	1,5	1,5	1,5	1,0	1,0	1,0	1,0
Filler density, g/cm3	1,2	0,8	0,5	0,7	0,9	0,3	0,5	0,6	0,5	0,7
Machining Parameters
Numbers of instances	1	2	3	4	5	6	7	8	9	10
Area efficiency, micrometers/min	0,5	60	52	80	34	28	42	44	4	2,2
Surface roughness, Ra, micrometers	0,02	0,28	0,30	0,32	0,12	0,14	0,1	0,12	0,03	0,04
Notes:
1. In the instances 1, 9 an 10 in basic abrasive pellets synthetic diamond powder of ACM brand with diamond cut 5/3 micrometers was used, in the instances 2, 3 and 4 diamond powder of AC4 brand with diamond cut 50/40 micrometers was used, and in the instances 5-8 diamond powder of AC4 brand with diamond cut 20/14 micrometers was used

[0063] The grit of auxiliary abrasive indicated in Table 2 makes 0.01-0.5 from the grit of basic abrasive pellets.

[0064] 2. In the instances 2,5,6 the basic and auxiliary abrasive pellets was in ratio of 1:1, in the instances 4,7,8,9 such ratio was 4:1, and in the instances 1,3,10 such ratio was 1:6.

[0065] As it follows from aforecited results, the proposed polishing tool, manufactured in compliance with proposed invention, has high cutting properties and provides high quality of machining.

[0066] Information sources:

[0067] 1. WO 94/17956, MKI B 24B7/16, prior. 18.08.94

[0068] 2. Inventors Certificate USSR 1311921, MKI B24D7/14, 1987

[0069] 3. Inventors Certificate USSR No. 1465439, MKI B24 D3/34, 1990

Claims

1. The polishing tool, containing chuck with abrasive units attached thereto, with filler, containing abrasive, placed in space between abrasive units, differing that the abrasive units are made in the form of pellets, the filler density makes 0.2-0.8 from density of the abrasive pellets, and the grit of the filler abrasive makes 0.01-0.5 from the abrasive pellets grit.

2. The polishing tool according to claim 1, with the filler in space between abrasive units is made in the form of auxiliary abrasive pellets attached to the chuck surface.

3. The polishing tool according to claim 2, noted by the quantity ratio of basic and auxiliary pellets is chosen in the range from 1:6 to 4:1.

4. The polishing tool according to claim 1, differing that the filler is placed in the whole space between abrasive pellets, and penepoxide, added with the composition of abrasive and fine-dyspersated aminoplast and/or phenoplast powder, is used as filler, at the same time quantity of abrasive and aminoplast and/or phenoplast in the filler makes correspondingly 15-30% and 10-40% from the penepoxide mass.

5. The polishing tool according to claim 4, noted by the density of the filler makes 0.05-0.2 from the density of the abrasive pellets.

6. The composition for the polishing tool manufacture, containing epoxy resin, diamond containing abrasive, hardener and filler, differing that it additionally contains polyhydride siloxane with following components ratio in relative mass portions:

7. The composition according to claim 4, differing that it additionally contains formic acid in amount of 1.0-10 relative mass portions as a functional additive.

8. The composition according to claims 6 and 7, with the combination of polirit, based on not less than 70% of cerium dioxide, microbeads made of silicon dioxide sized from 10 to 100 nanometers, graphite powder and fine-dyspersated metal powder is used as a filler.

9. The composition according to claims 6, with the composition of cerium dioxide with aminoplast, being thermosetting pressing mass, based on urea-, carbamide-, melamine- and/or carbamidemelamineformaldehyde resin and/or phenoplast, being thermosetting pressing mass, based on formaldehyde resin, is used as filler, at that cerium dioxide and aminoplast and/or phenoplast in the composition are in the ratio of 1:(0.1-10).

10. The composition according to claim 6, noted for the composition of diamond dust with auxiliary abrasive, being corundum or silicon carbide or boron carbide or boron nitride or their composition, is used as abrasive. The ratio of the diamond dust and auxiliary abrasive in the composition is in the range (0.01-10):(50-0.5) relative mass portions.

12. (New) The composition according to claim 11, wherein said composition additionally contains a functional additive comprising formic acid in amount of 1.0-10 parts by weight.

13. (New) The composition according to claim 11, wherein said filler is a composite of an abrasive based on not less than 70% of cerium dioxide, microbeads made of silicon dioxide sized from 10 to 100 nanometers, a graphite powder and a finely dispersed metal powder.

14. (New) The composition according to claim 12, wherein said filler is a composite of an abrasive based on not less than 70% of cerium dioxide, microbeads made of silicon dioxide sized from 10 to 100 nanometers, a graphite powder and a finely dispersed metal powder.

15. (New) The composition according to claim 11, wherein said filler is a composite of cerium dioxide with aminoplasts, said aminoplasts being thermosetting pressing mass, based on urea-, carbamide-, melamine-, and/or cabamidemelamineformaldehyde resin and/or phenoplasts, said phenoplasts being thermosetting pressing mass, based on formaldehyde resin, wherein said cerium dioxide and aminoplast and/or phenoplast in the composite are in a ratio of 1:(0.1-10).

16. (New) The composition according to claim 11, wherein said diamond containing abrasive is a composite of diamond dust with an auxiliary abrasive, said auxiliary abrasive being corundum or silicon carbide or boron carbide or boron nitride or their mixture, wherein a ratio of the diamond dust and the auxiliary abrasive in the composite is in a range of (0.01-10):(50-0.5) in parts by weight.

17. (New) A polishing tool, containing a chuck with abrasive units attached thereto, with a filler, containing an abrasive, placed in space between the abrasive units, wherein the abrasive units comprising the composition according to claim 11 and are made in a form of abrasive pellets, a filler density makes 0.2-0.8 from a density of the abrasive pellets, and a grit of the filler abrasive makes 0.01-0.5 from a grit of the abrasive pellets.

18. (New) The polishing tool according to claim 17, wherein the filler in space between abrasive units is made in the form of auxiliary abrasive pellets attached to a chuck surface.

19. (New) The polishing tool according to claim 18, wherein a quantity ratio of basic and auxiliary pellets is chosen in a range from 1:6 to 4:1.

20. (New) The polishing tool according to claim 17, wherein the filler is placed in a whole space between abrasive pellets, and the filler is a composite of penepoxide, added with a mixture of abrasive and finely dispersed aminoplast and/or