HU200617B - Cobalt alloy binding material for producing diamond-grained frame-saw segments - Google Patents

Abstract

The binder according to the invention is characterized in that it contains from 0.1 to 2% by weight, preferably from 0.8 to 1.3% by weight, of Fe alloy and from 0.5 to 1.5% by weight of the W alloy. Scope of the description: 4 pages, without figure <0 O 8 3 -1-

Description

BACKGROUND OF THE INVENTION The present invention relates to a cobalt alloy binder for the production of diamond grain germ segments. More particularly, the present invention provides for the production of Co-based low alloy binder (matrix) diamond grain gateway segments for marble-limestone sawing.

Natural and artificial rock (marble-granite-limestone agglomerate) is one of the most important building materials. Diamond tools are used mainly for rock processing.

In the 1960s and 65s, tools with diamond-grain segments, including gateway segments, began to be used instead of the previous sand and steel-shot abrasion.

The lifetime of the segment is primarily influenced by the composition of the binder (matrix) that holds the diamond grains and the quality of the diamond grains.

Today, 80% of industrial diamond particles are produced artificially, where high quality diamonds crystallize in the form of a regular octahedron. Its surface is perfectly smooth and therefore difficult to hold in the binder, as opposed to natural diamond grains produced from larger particles by crushing or breaking. However, the disadvantage of natural diamond particles is that on the one hand, it is not possible to produce uniform particles by fracture and, on the other hand, there is a high standard deviation depending on the mining site.

The development of a good binder (matrix) already raises metallurgical and metallophysical problems, especially in gatter segments. In addition to the mechanical engagement-support grip, consideration should be given to the atomic bond formed by the solid diffusion on the surface of the metal binder - the diamond particle.

The binder may be any metal powder of suitable particle size and purity (preferably less than 2 µm), either solid state diffusion (Co, W, Mo, Ni, Fe, V, WC) or liquid phase (Cu, Sn, Zn) results in a higher quality, harder binder.

U.S. Patent No. 4,442,180 proposes a sintered-edged material for cutting tools that contains Mo, W carbide crystals. The diamond powder or boron nitride powder is placed in this cermet and sintered at a temperature and pressure such that said powders are thermodynamically stable and bond to the cermet. The resulting material has particularly high hardness and abrasion resistance.

The disadvantage of this solution is that it is too hard and abrasion resistant, so it does not move away fast enough to release new diamond particles in the binder, so that the tool will not be self-sharpening and will not cut continuously.

A metal that is too soft or abrasive (eg, Cu-Sn, Cu-Zn) allows for the early removal of diamond particles without being sufficiently worn, thus preventing the diamond's hardness and abrasion resistance from being properly utilized.

U.S. Patent No. 4,626,281 proposes a premix comprising 3 to 10% by weight of boron carbide, 70 to 90% by weight of tungsten or molybdenum, the remainder being nickel and iron 2 or a mixture thereof. From this composition, at least 85 Rockwell A hardness materials can be formed. Relatively low density: 7-7.4 g / cm ³ .

However, this solution does not provide the cutting edges with the desired properties.

The binder of high grade gatters has a hardness of HRA 58-62 and a density of 8.25-8.4 g / cm ³ , which can be achieved by parameters either by pressure shrinkage (compression) or other special shrinkage technology. In addition, the binder should be highly tough, hard, abrasion resistant, and hold the diamond particles well.

Therefore, we chose cobalt powder as the base metal, which is commonly used in high performance tools. The Co powder can be obtained in a particle size of less than 2 µm, which is well-compressible, well-shrinkable and produces a compact, even-textured matrix.

In our work, it has been surprisingly discovered that the addition of a small amount of Fe and W powder to the Co powder results in a binder having a hardness close to that of the cobalt and a longer life than the cobalt binder.

Accordingly, the present invention provides a Co-based low alloy binder (matrix) for the production of diamond granular germ segments, preferably for marble-limestone sawing, wherein the binder is 0.1-0.2% by weight, preferably 0.8-1.3% by weight of Fe alloy and Contains 0.5% to 1.5% by weight of alloy W - other Co. The particle size of the alloys is expedient

1-2 pm.

The reason for the low lifetime of low Fe (W) alloys may be that since diamond is pure carbon, 1 to 2 pm Fe and W metal powders react in solid form with diamonds than carbon and bind better to the diamond particles in the cobalt binder than we would only shrink it in pure cobalt metal powder.

Tungsten reacts with diamond (carbon) during shrinkage to form a thin layer in the form of tungsten carbide (WC) on the surface of the diamond grain, thus retaining it better in the binder. This was also demonstrated by microscope analysis.

Iron reacts with the diamond (carbon) to form iron carbide (Fe3C) (chemical reaction) and also promotes better retention of the diamond in the binder.

Fine metal powder particles (about 1 to 2 pm) are needed to provide a small amount (0.1 to 2.0% by weight) of statistically many particles uniformly in the binder, on the surface of the diamond particles, and not to have a large difference size cobalt base powder, thereby promoting a good and even distribution of the alloying powder (additive powder).

The low-alloy gatter segments of the present invention are produced by the following hot stamping technology:

Shrinkage temperature: 760-820 'C.

Shrinkage specific pressure: 25-35 MPa

Shrinkage hold time: 4-6 minutes

The binder according to the invention is illustrated by the following examples:

EN 200617 Example A /

Raw materials:

Co powder COC type 1.2 µm particle size

W powder Tungsram 1.0 µm grain size

Fe powder Electrolyte 1-2 pm particle size

diamond:

Artificial Type MBS 70, 0.420.59 mm in grain size, 0.16 g diamond for 6 g matrix, approx. Corresponds to a concentration of 35% by weight.

Matrixbemérés:

Co 98.7% by weight W 0.5% by weight Fe 0.8% by weight

Matrix Diamond Granule Mixing: Spraying with 10% w / w paraffin solution and mixing in a Tuibula mixer for 30 minutes.

Matrix diamond grain mixture weighing: to the nearest 0.1 g, on a Mattler scale with a 12-well graphite tool.

Compression-shrinkage in pressurized equipment:

when shrinking, the specific pressure is 30 MPa shrinkage temperature is 780 ° C shrinkage heat retention for 5 minutes.

Segment hardness HRA 58-62 (measured per serving)

Density of the segment is 8.3-8.4 g / cm ³ (measured per serving)

The gatter segments obtained in the example were capable of cutting 245 fm, while the same purpose gatter segments supplied by the Belgian DIAMANT BOART have a guaranteed longevity of 110 fm / sheet in vertical cutting lengths when transporting Diamant Boart segments and soldering and 160 fm / sheet for complete soldered dowels made by Diamant Boart.

Example 2

All were carried out as in Example 1, except that W was 15% by weight and Fe was 1.3% by weight.

The resulting gatter segments had a lifetime of 230 µm.

Claims (2)

Cobalt alloy binder (matrix for the production of diamond-grained gavel segments, preferably for marble-limestone sawing, characterized in that the binder is 0.1 to 2% by weight, preferably 0.8 to 1.3% by weight of Fe alloy and 0.5 to 1.5% by weight % by weight of alloy W - other Co. 2. The binder according to claim 1, wherein the alloys have a particle size of 1-2 µm.