Binder for the fabrication of diamond tools

Abstract

This invention relates to powder metallurgy, more specifically, to methods of fabricating hard alloy items. The invention can be used as an iron, cobalt or nickel base binder for the fabrication of diamond cutting tools for the construction industry and stone cutting, including segmented cutting discs of different designs and wires for reinforced concrete and asphalt cutting used in the renovation of highway pavements, runways in airports, upgrading of metallurgical plants, nuclear power plants, bridges and other structures, monolithic reinforced concrete cutting drills, as well as discs and wires for the quarry production of natural stone and large scale manufacturing of facing construction materials. This invention achieves the objective of providing binders for the fabrication of diamond tools having higher wear resistance without a significant increase in the sintering temperature, as well as higher hardness, strength and impact toughness. The achievement of these objectives by adding an iron group metal as the main component of the binder composition and alloying additives in the form of nanosized powder in accordance with this invention is illustrated with several examples of different type binders for the fabrication of diamond tools.

Claims

1. A binder for the fabrication of diamond tools, the binder consisting of (1) a basis and (2) an alloying additive, wherein said binder is a material sintered and pressed at the sintering temperature, wherein said basis consists of iron, cobalt, or nickel, and said alloying additive is tungsten carbide, zirconium dioxide, or niobium carbide, wherein the alloying additive being in the form of a powder with particles sizes less than 100 nanometers, and wherein the alloying additive is in an amount of 2-10 wt. %, wherein the claimed ranges of wt. % refer to the alloying additive.

2. The binder of claim 1 wherein the alloying additive is in an amount of 10 wt. %.

Description

EMBODIMENTS OF THE INVENTION

(1) The binders can be synthesized by powder metallurgy, i.e. sintering followed by pressing at the sintering temperature. This method is highly productive because the overall duration of material heating to the sintering temperature, exposure to the sintering temperature, pressing and cooling to room temperature does not exceed 15 minutes. The high heating rates and the uniform temperature distribution in the processing chamber are provided by passing electric current through the sintering mold which is used also as the pressing mold. Upon the completion of the exposure to the sintering temperature, pressing is started immediately in order for the required density and shape of the manufactured items to be maintained. The pressing mould design allows the process to be conducted in an inert or protective atmosphere, this increasing tool quality.

(2) Contents of the alloying additives that are below the minimum limit of the concentration range shown above (1 wt. % for iron and cobalt and 1.6 wt. % for nickel) are insufficient for their homogeneous distribution in the bulk of the material, and their effect on the structure and properties of the resultant material is negligible. If, on the other hand, the maximum limit of the abovementioned concentration range (15 wt. %) is exceeded, the concentration of the alloying material (the nanocomponent) becomes excessive. As the alloying material has a higher hardness compared with iron group metals, it acts as a stress concentrator thus strongly embrittling the material and reducing the mechanical properties and wear resistance of the binder.

(3) Tables 1, 2 and 3 show examples illustrating binder properties as a function of composition.

(4) TABLE-US-00001 TABLE 1 Rockwell Impact Hardness Bending Tough- (HRB), Strength ness, 1.5 mm/ σ.sup.bend, KCU, Composition, wt. % 980 N* MPa J/cm.sup.2 100% Fe.sub.binder(B13) 88 920 3.36 99.3% Fe.sub.binder + 0.7% alloying 93 915 3.36 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 99% Fe.sub.binder + 1.0% alloying 95 919 3.37? additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 98% Fe.sub.binder + 2.0% alloying 98 1198 3.80 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 90% Fe.sub.binder + 10.0% alloying 104 1250 4.04 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 85% Fe.sub.binder + 15.0% alloying 101 1190 3.87 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 80% Fe.sub.binder + 20.0% alloying 90 850 3.15 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 78% Fe.sub.binder + 22.0% alloying 92 953 3.01 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) *Hardness was measured at the force 980 N using the ball 1.5 mm in diameter

(5) TABLE-US-00002 TABLE 2 Impact Bending Tough- Rockwell Strength ness, Hardness, σ.sup.bend, KCU, Composition, wt. % 1.5/980* MPa J/cm.sup.2 100% Co.sub.binder(B13) 88 920 3.36 99.3% Co.sub.binder + 0.7% alloying 90 919 3.37 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 99% Fe.sub.binder + 1.0% alloying 93 919 3.37 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 98% Co.sub.binder + 2.0% alloying 98 1198 3.80 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 90% Co.sub.binder + 10.0% alloying 104 1250 4.04 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 85% Co.sub.binder + 15.0% alloying 103 1220 3.90 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 80% Co.sub.binder + 20.0% alloying 101 1190 3.87 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 78% Co.sub.binder + 22.0% alloying 92 953 3.01 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) *Hardness was measured at the force 980 N using the ball 1.5 mm in diameter

(6) TABLE-US-00003 TABLE 3 Impact Bending Tough- Rockwell Strength ness, Hardness, σ.sup.bend, KCU, Composition, wt. % 1.5/980* MPa J/cm.sup.2 100% Ni.sub.binder (B13) 88 920 3.36 99.3% Ni.sub.binder + 0.7% alloying 93 919 3.37 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 99% Ni.sub.binder + 1.65% alloying 98 1198 3.80 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 98% Ni.sub.binder + 2.0% alloying 101 1200 3.90 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 90% Ni.sub.binder + 10.0% alloying 104 1250 4.04 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 85% Ni.sub.binder + 15.0% alloying 102 1200 4.00 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 80% Ni.sub.binder + 20.0% alloying 102 1190 3.87 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) 78% Ni.sub.binder + 22.0% alloying 92 953 3.01 additive (Al.sub.2O.sub.3 or WC or W or ZrO.sub.2 or NbC or C.sub.diamond UFP + Ni or C.sub.diamond UFP + Ag) *Hardness was measured at the force 980 N using the ball 1.5 mm in diameter

(7) The binder materials according to this invention will provide for better economic parameters as compared to the counterpart materials of the world's leading manufacturers with respect to the price/lifetime and price/productivity criteria. For example, the diamond containing segments for asphalt cutting discs are operated in a superhard abrasive medium. The conventional matrix hardening method by introducing tungsten carbide has a concentration limitation due to the consequent increase in the required sintering temperature (this, in turn, reduces the strength of the diamonds and causes additional wear of the process equipment).

(8) The introduction of alloying additives in the form of nanosized particles in the binder allows increasing its wear resistance without a significant increase of the sintering temperature. Granite cutting disc segments are used in the large scale manufacturing of construction facing materials and are therefore a large scale product, too. Their production costs and unit operational costs are an important economic factor in the respective production industries. The transition from conventional binders to iron group metal base binders will reduce the raw material costs. In the meantime, the operational parameters (wear resistance, hardness and impact toughness) of such binders will be retained by introducing nanosized particles of WC, Al.sub.2O.sub.3 and other additives.

(9) The materials used as binders for the synthesis of pearlines suitable for hot pressing have largely reached their operational limits. Further development is oriented to the hot isostatic pressing technology which requires very large capital investment in process equipment, often reaching millions dollars. On the other hand, hot pressing combined with the introduction of nanosized particles allows pearlines to be obtained with parameters close to those obtained using the hot isostatic pressing technology.

(10) The introduction of alloying additions, i.e. tungsten carbide, tungsten, aluminum oxide, zirconium dioxide or niobium carbide, in the form of nanosized powder provides for the high strength, heat conductivity and cracking resistance of the material. The controlled small additions of the alloying components provide for a unique combination of properties, i.e. strength, hardness, cracking resistance and cutting area friction coefficient thereby allowing the service life of tools operated under extremely high loading conditions to be increased by 10-20% compared to the initial ones, without compromise in the cutting capacity.