DE2010183A1 - Coated diamond - Google Patents

Description

DR. ING. E. HOFFMANN-DIPL ,. ING. W. EITLE DR. RER. NAT. K. HOFFMANN PATE NTAIfAVJLLTE D-BOOO MÖNCHEN 80 - MARIA-THERES1A-STRASSE 6 - TELEPHONE (0811) 441061

PERMATTACH DIAMOND TOOL CORPORATION MiIford, New Hampshire, USA

Coated diamond

The invention relates to a coated diamond for cutting, grinding and the like.

At present, diamond particles are supported for cutting, grinding and the like in such a way that they are attached individually or in a multiplicity to the surface of a carrier or that they are attached in single or multiple layers or in other conglomerated structures, partly or entirely in metallic, embeds ceramic or organic matrices.

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With this attachment or embedding · the bond is with the surface of the diamond usually either when the diamond is adhered to the support or when it is hardened or sintering the matrix. When it was recognized that the conventional binding metals, such as copper and Silver alloys, which give diamonds only slightly higher bonds than mechanical bonds, suggesting inability these alloys to wet the surface of the diamond and for the absence of any chemical bonds, which give more than just very low adhesive forces, has been the search for improved ones Bonds started soldering or embedding in the presence of transition metals, especially of Titanium or zirconium, either in the form of metals or hydrides.

In US Pat. No. 2,570,248, the use of a mixture of titanium hydride and copper based on the Connection of the two miteian-.the body to be soldered is applied, proposed. According to the USA patent 2,728,651 is said to be a slurry of titanium hydride in an organic liquid on the diamond apply and sprinkle these titanium hydride coated diamonds on a layer of an alloy metal, whereupon the hydride is heated and decomposed, the solder is melted and the titanium is dissolved.

However, both inventors were aware of the fact that heating the applied coating in the presence of Titanium must be carried out in a vacuum or in a reducing atmosphere, making expensive facilities were required to adapt the large vacuum chambers to the holding devices or to the die presses to provide.

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In U.S. Patent 3,293,012 there is a deformation process described the diamond powder together with a mixture of a powdered hydride and a metallic Binder in alcohol along with an infiltration agent from a molten metal is used. This process is also carried out in a non-oxidizing atmosphere carried out under pressure.

In the preliminary work leading to this invention, it has it turns out that one was wrong if one tried while the diamond was adhering or embedding to form a strong interfacial bond of the diamond in an outer carrier. It was also not recognized that it is associated with disadvantageous consequences if the titanium or zirconium components are mixed with alloys, which are not reactive towards the diamonds, or in close proximity to it at the same time as a heat treatment to subject, as this creates an indiscriminate mono-bonded layer of the molten alloy and the dissolved titanium is formed.

In contrast, it is an object of the present invention to provide individual diamond particles which Wear metallic coatings over their entire surface, which make it possible. The coated diamonds to connect with each other and with other surfaces without im Vacuum or in inert gases must be used and with which high adhesive forces on the surface of the diamond are present. Another object of the invention is diamond bonds to provide great strength by removing the interfacial bond of the diamond surface trains before attaching the diamond to the outer carrier

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attached or inserted into a matrix. Thus, therefore, in the formation of the surface bond of the diamond only materials reactive with diamond may be present. Another object of the invention is to provide a less oxidizable To create protective layer or less oxidizable protective layers, so that the subsequent adhering or embedding with non-oxidizable solder alloys in the air without Oxidation of titanium can be carried out. Working in a non-oxidizing atmosphere is therefore only required during the formation of the interface of the diamond surface and then no more.

The invention therefore relates to a coated diamond for cutting, grinding and the like, which is characterized by is that it consists of a single diamond particle that has a thin, continuous layer of substantially uniform thickness of a transition metal which is substantially is selected from the group consisting of titanium and zirconium or mixtures thereof, whereby a single, uniform, composite body with a high strength bond at the interface between the layer and the diamond particle is formed, which corresponds to the high cohesive bond of a metal-carbide structure and wherein the outer surface of the composite body is not carbide.

The invention also includes a process for producing such a coated diamond, which consists in mechanically applying a layer of powdered transition metals from the group titanium and zirconium or their mixtures or their hydrides, the particles and the layer, to the surface of an individual diamond particle to a temperature at least yon 35Q ⁰ C in a non-oxidizing atmosphere heated to thin the whole particles having a

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continuous layer of transition metal to be coated and to bond the layer to the surface of the diamond and that the coated particle is in the non-oxidizing atmosphere cools and, if necessary one or more completely overlapping layers of different less oxidizable materials brings up,

When carrying out the method according to the invention a plurality of individual, separate diamond particles usually arranged together, for example in shape a batch, it has been shown that the product is individual, separate, non-sticking, flowable Represents diamond particles coated with metal.

Essentially, the invention produces individual diamond particles made available, which are provided with firmly bonded coatings made of the transition metals that react with the greatest probability / with diamond or carbon, namely with titanium or zirconium or their mixtures.

The coatings are in the form of thin continuous layers of substantially uniform thickness, which are associated with high adhesive forces along the entire interface between the layer and the diamond are, the adhesive forces are comparable to those generated by the formation of chemical bonds, as shown in a titanium or zinc carbide structure occur.

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Instead of getting these metals purely mechanically from a slurry or other dispersion of which applies for subsequent dissolution in a molten metal binder or solder, it has been found that when this surface is dry mechanically deposited, sometimes at least in the hydride form, in the absence of any other binder on the surface of the diamond and when heated to a suitable one Temperature in the vacuum forms a bond that has a surprisingly high adhesive force, with the At the interface, a reaction or an electron interrelation takes place, which in terms of its chemical or physico-chemical nature of the formation of a carbide corresponds to or is equivalent. Because the titanium and the zircon are not in a non-wetting binder is dissolved and it is free of alloys and not otherwise contaminated, is its attraction and attachment on the surface of the diamond of a completely different order of magnitude.

After the film or coating of transition metal is applied over the entire surface of the diamond particle has been, another layer of a different, less oxidizable metal, a ceramic material or a resin may be applied to enable subsequent attachment to be carried out without causing non-oxidizing atmospheres must be used.

One of the advantages of the present invention is that with an entire batch of mechanically applied Layered diamond particles that are interconnected

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are in contact, the layers can be converted into heat-bonded coatings at the same time, without the adjacent particles sintering together, which is due to the fact that the heat treatment at is carried out at a much lower temperature than that at which the titanium or zirconium layers melt. When trying to get diamond particles with molten brazing materials or with bonding alloys to be coated, then a fusion takes place between the coated diamonds, so that no individual, flowable ones Particles can be obtained, but a solid, melted mass. In contrast, according to the method of the invention, individual, uniform, free-flowing, coated diamond particles obtained 'which are further coated with one or more layers of different materials That can be the surfaces that are metallurgically exposed to air with external metals, organic or ceramic substrates or other carriers are readily connectable in the conventional manner.

Due to the small amount of non-diamond binder required or the required matrix material, bodies with a very high diamond concentration can be obtained that are up to 200 to 260 carats per 16.39 cm, when the body is hot pressed. Reducing the use of the non-diamond material to a minimum reduces friction and heat generation, when the body is used for cutting and grinding. The strength of the bond allows for greater The diamonds protrude from their supporting surface, creating a better margin and increased Lifetime can be achieved without the risk of falling out.

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The invention is to be explained below with reference to Examples 1 to 6 and FIGS. 1 to 6.

Example 1 (Figure 1)

Diamond chips weighing 200 carats together with 200 to 250 mesh, which have been cleaned with conventional solvents to free the surface of organic contaminants, are mixed with 6 g of powdered titanium or zirconium (at least 10 % or more in the hydride form) with 600 mesh placed in a mechanical drum dryer and treated at room temperature and atmospheric pressure until each diamond particle has an adherent layer of the powder on its entire surface.

The diamonds with the layers applied to them are then transferred together into a graphite crucible and

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A vacuum of about 10 mm Hg, but at least about

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^{10 mm Hg heated to a temperature of 850 to 900 0} C for a period of at least 10 to 15 minutes. The particles in the crucible are allowed to cool in vacuo and then removed from the vacuum chamber.

Each particle is individual and does not adhere to the other particles, with the exception of an occasional easily breakable one Adhesion that can be easily broken without damaging the surface. Under the microscope it can be seen that each particle forms a very thin, smooth, and uniform metal film of a substantially uniform one Has obtained starch, for example about 5 wt .- # des

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Total weight of the film and the diamond. In FIG. 1, 1 shows the diamond core, 2 shows the interface between diamond and titanium film and 3 shows the titanium film.

• The surprising size of the heat and vacuum induced interfacial binding leads to the conclusion that lie the high electrochemical activity of the Titans and his high ability in the presence of his Hydrids to wet the diamond, this one with the

has reacted diamond to form a carbide. However, it appears that, because of the limited amount of time, the carbide formation primarily only at the interface with the surface of the diamond, the outer one Surface of the smooth coating is uncarbided. This is evidenced by the fact that in the subsequent brazing a more than adequate metallurgical Adhesion of the coated particle is ensured, which would not be the case if the outer surface were carbidized would be because the conventional soldering materials on titanium carbide surfaces does not adhere well. Likewise, if the coated particles are then hot pressed, the coating is not loosened, as is the case with nickel-plated diamonds. The bonds that are made according to the Invention obtained, withstand the forces directed against the bond due to the different Expansion coefficients of the diamond and the coating arise.

The layer originally formed on the diamond particles is thus regarded as an inhomogeneous layer which differ from a titanium carbide content at the interface and near that towards a completely uncarbided titanium content on the outer surface and in the

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Proximity of it extends, creating the coated particle is made adhesive to metallic and non-metallic binding materials.

In any case, the coated particle has the high cohesion properties of a metal carbide structure on the Interface, however, allows the further application of protective layers to the outer surface of the coated Particle, which can be done according to the conventional methods, and with the result that external adhesions are obtained that are larger than those that would occur if the outer surface of the initial Layer would consist of titanium carbide. This dual function of the single applied titanium layer is thereby achieved that one omits from the coating the metal alloys or brazing materials that have been used up to now and the only low adhesive forces on the diamond resulted from the mechanical bonds only were little away. Another reason for this is that the depth of carbide formation is limited. Naturally, can the uncarbidized surface can then be cemented, for example by heating in packed carbon or in methane to reduce oxidation or to create a harder surface. This measure is not incompatible with the good adhesion to the subsequent binding materials.

Although the specified temperature range is preferred, the minimum temperature is about 350 ° C, which is sufficient high to dissociate the hydride, and the maximum temperature is the temperature at which the graphitization of the diamond under the prevailing conditions

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would take place, ie about 125O ⁰ C. However, it has been shown that an increase in temperature above 1000 ° C. is not associated with any advantage. The reaction time and temperature conditions should always be such that the formation of significant amounts of carbide on the outer surface of the coated particles is minimized. Due to this double puncture of the only applied layer, no other alloying or soldering materials need to be added to the original titanium coatings, as has been done up to now, which only led to low adhesive forces, which were more comparable to the purely mechanical bonds.

Example la

The procedure of Example 1 was repeated. with the exception that the applied layer is a mixture of 1 part by weight of titanium and 1 part by weight of zirconium (again partly in the form of hydrides) was used.

Example 2 (Figure 2)

A further layer of copper or nickel to a thickness of 0.05 to 0.10 mm is placed on the particle according to FIG. 1 plated on. Instead of the galvanic or the currentless Plating can also be done using conventional vacuum deposition methods including sputtering can be used.

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The coated particles are then embedded in a metallic matrix in the following manner to obtain the in Figure 2 (again in large enlargement) to form the product shown. Here 1 is the diamond particle, 2 the interface, 3 the titanium layer, 4 the copper or nickel layer and 5 a fragment of the metal matrix.

The particles are mixed with copper powder and hot-pressed in a graphite press or a cold press and then pressed sintered by the usual methods or infiltrated with solder. In the other case, a resin powder can also be used or used without a metallic or other filler. If the matrix is ceramic in nature, then the glazing methods can be used. The copper or nickel layer 4 can consist of successive Layers of copper and nickel are made up.

If desired, this can be coated with copper or nickel or particles doubly coated with copper or nickel sintered or fused together in situ at the sintering or fusing temperatures of the less oxidizable metals in a non-oxidizing atmosphere, creating a metallurgical cohesive bond is formed between the transition metal and the overlying less oxidizable metal. It is to point out that protective layers such as 4 are only important in those cases where further procedural measures without the use of non-oxidizing atmospheres should be carried out. The addition of a metal layer or however, metal layers are useful whenever pressing methods are used because the softer metal is the The surface of the mold is not damaged.

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Instead of mixing the coated particles with other metal powders, the coated diamond particles I ₃ 2 _} 3> j 4 can themselves be used as powdered metals according to the conventional powder metallurgical procedures, such as cold pressing, sintering or infiltration, in order to produce bodies impregnated with diamond

Example 3 (Figure 3)

A coated product prepared according to Example 2 can be applied to a tool by using a conventional brazing material between the coated particle and the cleaned surface of a steel shaft brings and then heats the soldering material with a gas torch in air to melt it. The resulting Product is shown in Figure 3. Therein 21 means the diamond, 22 the titanium layer, 24 the nickel or copper layer, 25 the brazing material and 26 part of the steel shaft.

Example 4 (Figure 4)

Coated particles produced according to Example 2 are coated with a layer of spongy iron, what can be done according to the following procedure:

A soldering material is applied to the coated particles and these are then cleaned with a powdery sponge iron mixed and placed in a vacuum or hydrogen oven

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brought to the iron particles on the surface of the coated Soldering diamonds.

A batch of these products is then embedded in a resin matrix in the conventional manner.

The product obtained in this way is shown in FIG. 4, in which 31 the diamond, 32 the interface, 33 the titanium layer, 34 a metal layer, 35 a soldering material, 36 Particles of the spongy iron and 37 a part of the Show resin matrix.

Example 5 (Figure 5)

A coated product produced according to Example 1 is covered with a coating of copper or nickel A thickness of about 0.05 to 0.10 mm plated. While This procedure introduces small hairs, fibers or threads made of ceramic, glass or metal into the metal plating solution Brought aluminum oxide and allowed to settle on the surface of the diamond in the course of about 25 minutes. the subsequent movement of the diamonds in the plating solution leads to further deposition of the hair the coated diamond particle during plating.

The hair-coated particles are then embedded in a resin matrix in the conventional manner to provide a Manufacture part of a grinding wheel, as shown in Figure 1st. 4l therein show a particle from one Natural or synthetic diamonds, 42 the interface, 43 the titanium layer, 44 a copper or nickel layer, 45 hairs and 46 part of the resin matrix,

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Example 6 (Figure 6)

FIG. 6 shows part of a machining tool an unusually high diamond concentration, which results in more cutting points and the risk of undercutting eliminated by treated abrasive particles.

A low carbon steel shaft is provided which has a cavity approximately 0.38 cm in diameter and has a depth of 0.64 cm.

Diamond particles bearing titanium coatings which have been applied according to the invention and which are coated with a nickel or Copper layer (or both) are coated at 750 ° C in air along with powdery Hot-pressed copper and silver solder alloys. By doing this, the product shown in Figure 6 is obtained. In it 51 diamond particles, 52 denote the interface, 53 the titanium layer, 54 the plated-on metal coating, 55 the solder alloy and 56 part of the with a hollow, rigid steel shaft.

Instead of the titanium layer as in Example 2 with Coating metal, the titanium can also be coated directly with a ceramic or a resin-like metal, by applying these substances in powder form and the applied Powder vitrified in a conventional manner or hot-pressed.

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As can be seen from the large number of products shown in the accompanying drawings, the products according to the Coated diamond particles made in accordance with the invention for the manufacture of a wide variety of cutting or grinding products used, e.g. by machining tools, machining disks, saw blades, grinding disks, Grinding wheel segments, either with a single or with several layers, saw blade segments or inserts, drill bits, tools for milling, drilling, turning, countersinking, tools with one or more points, tools for beveling and etching, and for wires and other saws and all other types of tools for drawing, fine grinding, cutting and grinding. These products can also be used to make machines for optical lenses or button inserts.

The protective metal layer can consist of any metallic binding materials that are electroplated or can be applied by electroless deposition, in a vacuum or by cathode sputtering. Such are e.g. Nickel, copper, iron, zinc, tin, silver, gold, cadmium or cobalt or their alloys and their mixtures.

Suitable soldering materials are e.g. copper bronze, copper-silver alloys, Copper-beryllium alloys, copper-zinc alloys and all other metallurgical brazing materials, those on the protective layer or on the layer of the transition metal if the metallic protective layer omitted, can adhere.

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Claims (1)

Patent claims 1. Coated diamond for cutting, grinding and the like, characterized in that that it consists of a single diamond particle, which over its entire surface a thin coherent Layer of substantially uniform thickness of a transition metal consisting essentially of the Group titanium or zirconium or mixtures thereof is selected, contributes, creating a single, uniform, composite Body with a high strength bond at the interface between the layer and the diamond particle is formed, which corresponds to the high cohesion bond of a metal-car bidgefüges and wherein the outer surface of the composite body is not carbide! 2. Coated diamond according to claim 1, characterized in that it also has carries one or more completely overlapping layers of a less oxidizable material. 3. Coated diamond according to claim 2, thereby characterized in that the less oxidizable material is a less oxidizable metal such as nickel or copper. 009837/1571 -XO- 4. Coated diamond according to claim 3, characterized characterized in that the less oxidizable metal in situ to the layer of the transition metal has melted. 5 · Coated diamond according to claim 2, characterized in characterized that small hairs, fibers or threads made of ceramic, glass or aluminum oxide on the metal are pinned. 6. Coated diamond according to claim 2, characterized characterized in that a layer of particles of spongy iron is adhered to the metal is. 7. Coated diamond according to claim 2, characterized characterized in that the less oxidizing material consists of two or more completely covering Layers made of ceramic material. 8. Coated diamond according to claim 2, characterized characterized that the less oxidizing Material consists of one or more completely overlapping layers of a resinous material. 9. Method of making a coated Diamonds according to one of Claims 1 to 8, characterized in that one is applied to the surface of a 009837/1571 individual diamond particles a layer of powdery Mechanically applies transition metals of the group titanium and zirconium, as well as their hydrides or mixtures thereof, the particles and the layer are heated to a temperature of at least 250 C in a non-oxidizing atmosphere, to coat the whole particle with a thin continuous layer of the transition metal and to connect the layer to the surface of the diamond and that the coated particle is cooled in the non-oxidizing atmosphere and, if necessary, a or applying several completely overlapping layers of a different, less oxidizing material. 10. The method according to claim 9, characterized in that the layer consists essentially of titanium and titanium hydride and that the particle and -4 the layer at a minimum pressure of 10 mm Hg for at least 10 minutes at a temperature from 350 to 1000 ⁰ C, preferably 85Ο be heated to 9oo ° C. 11. The method according to claim 9 or 10, characterized in that one by electrolytic or electroless deposition, or by applying one or more layers of one in a vacuum less oxidizable metal, such as nickel or copper, applies. 12. The method according to claim 11, characterized. geke η η shows that the one or more layers of the less oxidizable metal are melted in situ onto the layer of the transition metal. 009837/1571 Ij5. A method according to claim 11, characterized in that the plating solution small hairs, fibers or threads made of ceramic, glass or aluminum oxide are added and attached to the layer of the less oxidizable metal adheres. 14. The method according to claim 9 or 10, characterized characterized in that one or more completely on the layer of the transition metal superimposing layers of powdered ceramic or resinous material and that this is glazed or hot pressed. 009837/1571