Abrasive sawing wire, production method thereof and use of same

Abstract

An abrasive wire including a steel core and a coating including a binder and abrasive particles, the binder being formed by at least one iron alloy layer containing, by weight percent in relation to the weight of the binder: between 0 and 3% oxygen, advantageously between 0 and 2%; and between 0.3% and 9% of at least one element selected from the group including carbon, boron an phosphorous.

Claims

1. An abrasive wire comprising a steel core and a coating comprising a binder and abrasive particles, said binder being formed of at least one iron alloy layer containing, by mass with respect to the binder mass: from 0 to 3% of oxygen; and from 0.3% to 9% of at least one element selected from the group consisting of carbon, boron, and phosphorus.

2. The abrasive wire of claim 1, wherein the binder comprises two layers of iron alloy containing, by mass and independently from one layer to the other, from 0 to 3% of oxygen, and from 0.3% to 9% of at least one element selected from the group consisting of carbon, boron, and phosphorus.

3. The abrasive wire of claim 1, wherein the iron alloy comprises from 0.5 to 1.5% by mass of carbon.

4. The abrasive wire of claim 1, wherein the iron alloy comprises from 0.3 to 1% by mass of boron.

5. The abrasive wire of claim 1, wherein the iron alloy comprises from 1 to 9% by mass of phosphorus.

6. The abrasive wire of claim 1, wherein the iron alloy may comprise at least 97% by mass of iron, and less than 1% by mass of nickel, and/or less than 1% by mass of cobalt.

7. The abrasive wire of claim 1, wherein the abrasive particles are formed of grains at least partly covered with a film made of a metallic material.

8. The abrasive wire of claim 7, wherein the metallic material is ferromagnetic.

9. The abrasive wire of claim 1 wherein the at least one iron alloy layer contains, by mass with respect to the binder mass, from 0 to 2% of oxygen.

10. A method of manufacturing an abrasive wire, according to the steps of: electrodeposition on a steel wire of a composite coating comprising a binder and abrasive particles, by passing in an electrolyte bath (B1) comprising at least iron II ions, abrasive particles, and at least one source of at least one element selected from the group consisting of carbon, boron, and phosphorus; optionally, electrodeposition of an additional layer of iron alloy binder by passing in an electrolyte bath (B2) comprising at least iron II ions, and at least one source of at least one element selected from the group consisting of carbon, boron, and phosphorus wherein said binder is formed of at least one iron alloy layer containing, by mass with respect to the binder mass: from 0 to 3% of oxygen; and from 0.3% to 9% of at least one of the elements selected from the group consisting of carbon, boron, and phosphorus.

11. The abrasive wire manufacturing method of claim 10, wherein the baths (B.sub.1) and (B.sub.2) comprise, independently from each other, from 20 to 100 g/L of iron II ions.

12. A method of sawing a material selected from the group consisting of silicon, sapphire, and silicon carbide, said method comprising the steps of providing an abrasive wire and using the abrasive wire to saw the material; wherein the abrasive wire comprises a steel core and a coating comprising a binder and abrasive particles, said binder being formed of at least one iron alloy layer containing, by mass with respect to the binder mass: from 0 to 3% of oxygen; and from 0.3% to 9% of at least one element selected from the group consisting of carbon, boron, and phosphorus.

13. An abrasive wire comprising a steel core and a coating comprising a binder and abrasive particles, wherein said binder is formed of an iron alloy layer consisting of iron and, by mass with respect to the binder mass: from 0 to 3% of oxygen, and from 0.3% to 9% of phosphorous.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a device enabling to obtain the abrasive wire according to a specific embodiment of the invention.

(2) FIG. 2 illustrates a cross-section view of the abrasive wire according to a specific embodiment of the invention.

(3) FIG. 3 illustrates a cross-section view of an abrasive particle of the abrasive wire according to a specific embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) Device (2) illustrated in FIG. 1 enables to implement a method of electrodeposition on a steel wire (4) to prepare the abrasive wire (3) according to a specific embodiment of the present invention.

(5) The method especially comprises the steps of: unwinding a steel wire (core) (4) stored in the form of a coil (24), along the direction of arrow F; optionally, degreasing the steel core (4) in an alkaline medium; optionally, pickling the steel core (4) in an acid medium; optionally, passing steel core (4) through a magnetization device (26) which applies a magnetic field, having an intensity advantageously greater than 800 A/m. Core (4) is thus permanently magnetized: electrodepositing on a steel core a composite coating comprising a binder and abrasive particles, by passing in a bath (B.sub.1) (36) of electrolyte (38) comprising at least iron II ions, and abrasive particles (6), and at least one source of at least one element selected from the group comprising carbon, boron, and phosphorus; optionally, electrodepositing a second binding layer by passing in a bath (B.sub.2) of electrolyte (52) comprising at least iron II ions, and at least one source of at least one element selected from the group comprising carbon, boron, and phosphorus; obtaining the abrasive wire (3); optionally storing the abrasive wire (6), advantageously in the form of a coil (68) by means of a motor (70).

(6) The device (2) used comprises a source (28) which generates an electrolysis current i.sub.e. The positive terminal of the source (28) is connected to electrode (40) located in bath (B.sub.1) (36) of electrolyte (38) which is contained in vessel (34). The electrode (40) is advantageously made of pure iron. The negative terminal of source (28) is connected to two conductive pulleys (30) and (48) arranged on either side of vessel (34) via electric conductors (32) and (46). The two conductive pulleys (30) and (48) enable to provide two points (A) and (B) of mechanical contact with steel core (4)n which is thus connected to the negative terminal of source (28).

(7) Device (2) optionally comprises a device (44) for magnetizing abrasive particles (6) and steel core (4) once it is immersed in bath (B.sub.1) (36). It is positioned above bath (B.sub.1) (36).

(8) The abrasive particles used may be magnetic to allow a fast electrodeposition of the external composite coating on the steel core. They can thus be attracted by the steel core, which is magnetized during this process.

(9) As already mentioned, the magnetic properties of the abrasive particles may in particular originate form a magnetic film covering them.

(10) The steel core is thus covered with a coating made of binder and of abrasive particles by electrodeposition on passing in the bath (B.sub.1).

(11) According to a specific embodiment, a second binder layer may then be deposited on the steel core, by passing in second bath (B.sub.2) (52).

(12) Second bath (B.sub.2) (52), which is contain in vessel (50), comprises an electrolyte. It advantageously comprises no abrasive particles.

(13) The step of electrodeposition of the second binder layer comprises, in particular, immersing the steel core covered with a first binder layer and with abrasive particles, in a bath having an electrode (54) connected to the positive terminal of a second current source (56) arranged therein. Electrode (54) is advantageously made of pure iron.

(14) The negative terminal of second current source (56) is connected to two conductive pulleys (62) and (64) arranged on either side of vessel (50) containing second bath (B.sub.2) (52) via electric conductors (58) and (60).

(15) Conductive pulleys (62) and (64) provide the connection between steel core (4) and the negative terminal of second current source (56) at contact points (C) and (D).

(16) After the passing through the second electrolyte bath, abrasive wire (3) is obtained. It may be stored in the form of a coil (68).

(17) As already indicated, the device (2), and its implementation according to a specific embodiment are described in further detail in the patent application filed under number FR12 53017.

(18) As shown in FIG. 2, abrasive wire (3) according to the invention has a core (4) coated with a first binder layer (10) partially covering abrasive particles (6).

(19) According to this specific embodiment, the abrasive wire further comprises a second binder layer (12) covering abrasive particles (6). This second binder layer is advantageously more resistant to cracking (that is, less brittle) and more resistant to corrosion, than the first layer. It may be softer than the first layer (10) covering the steel core (4).

(20) The two layers (10) and (12) and abrasive particles (6) form external composite coating (8) of abrasive wire (3).

(21) According to a specific embodiment, abrasive particle (6) comprises an abrasive grain (16) covered with a film (18) (FIG. 3). The film is advantageously made of a metallic material, possibly ferromagnetic, to ease the electrodeposition of the particles on steel core (4). Indeed, the electrodeposition of the external composite coating is advantageously implemented in the presence of particles covered with a metal film, possibly ferromagnetic.

EMBODIMENTS OF THE INVENTION

(22) A plurality of abrasive wires (examples 1-6) have been prepared from a steel core in the hardened state. The steel core comprises 0.8% of carbon, it has a 0.12-millimeter diameter.

(23) Operating Procedure:

(24) The wires have been prepared by electrodeposition in a first electrolyte bath (B.sub.1) comprising abrasive particles, to form an external composite coating on the steel core. The composition of each of the elements is summarized in table 1.

(25) The abrasive particles used are diamonds (from 12 to 22 m) coated with nickel. The nickel mass forms 56% of the total mass of the coated abrasive particles.

Example 1: Iron-Based Binder (Fe)

(26) The treatment conditions of the steel core in bath (B.sub.1) are the following:

(27) current density: 5 A/dm.sup.2

(28) temperature: 55 C.

(29) anodes: pure iron

(30) The iron-based coating thus obtained contains approximately 5% of oxygen. It has a hardness of approximately 400 Hv.

Example 2: Binder Based on Iron and Carbon (Fe+C)

(31) The treatment conditions of the steel core in bath (B.sub.1) are identical to those of example 1 except for the current density and the presence of citric acid and of L ascorbic acid.

(32) Indeed, the carbon content in the binder increases with the current density. Below 0.5 A/dm.sup.2, the carbon content is smaller than 0.5%, which percentage may appear to be insufficient to have an influence on the hardness of the deposit (binder).

(33) However, when the current density is greater than 2 A/dm.sup.2, the carbon content stabilizes around 1.5%.

(34) However, in practice, the current density is advantageously smaller than 2 A/dm.sup.2. Indeed, beyond 2 A/dm.sup.2, the binder has an oxygen content greater than 3% by mass, which quantity embrittles the deposit (binder).

(35) The iron-based coating at 1 A/dm.sup.2 contains approximately 1% of carbon, with approximately 2% of oxygen.

(36) The hardness of the deposit increases from 500 Hv (0.5% of carbon) to 800 Hv (1.5% of carbon).

Example 3: Binder Based on Iron and Boron (Fe+B)

(37) The treatment conditions of the steel core in bath (B.sub.1) are identical to those of example 1, also in the presence of boric acid and of borane dimethylamine.

(38) The coating thus obtained is made of an iron and boron alloy (from 0.3 to 0.7%). It further comprises oxygen traces (<2%).

(39) Its hardness is approximately 300 Hv.

(40) Boron additions from 0.3 to 0.7% appear to lower the oxygen content of the iron deposit, and thus, to lower the brittleness of the electrodeposited metal.

Example 4: Binder Based on Iron, Boron, and Carbon (Fe+C+B)

(41) The treatment conditions of the steel core in bath (B.sub.1) are identical to those of example 1, also in the presence of citric acid of L ascorbic acid, of boric acid, and of borane dimethylamine.

(42) The coating thus obtained is made of an alloy of iron, of carbon (1%), and of boron (from 0.3 to 0.7%), with oxygen traces (<2%).

(43) Its hardness is approximately 600 Hv.

(44) At 5 A/dm.sup.2, the deposit is not brittle.

Example 5: Binder Based on Iron and Phosphorus (Fe+P)

(45) The treatment conditions of the steel core in bath (B.sub.1) are identical to those of example 1, also in the presence of sodium hypophosphite and possibly of aluminum sulfate.

(46) The hardness is approximately 300 Hv for 1% of phosphorus.

(47) The hardness is approximately 900 Hv for 9% of phosphorus.

(48) The brittleness is lower when the phosphorus content is in the range from 1 to 6%.

(49) The obtained deposits contain from 1% to 9% of phosphorus.

(50) They contain less than 3% of oxygen.

(51) Their corrosion is more difficult.

(52) The addition of from 1% to 9% of phosphorus in the electrodeposited iron appears to lower its oxygen content (and thus its brittleness) and its sensitivity to corrosion.

Example 6: Binder Based on Iron, Carbon, and Phosphorus (Fe+C+P)

(53) The treatment conditions of the steel core in bath (B.sub.1) are identical to those of example 1, also in the presence of citric acid of L ascorbic acid, of sodium hypophosphite, and of aluminum sulfate.

(54) TABLE-US-00001 TABLE 1 Compositions of electrolytes used in examples 1-6. The quantities are expressed in g/L. Examples 1 2 3 4 5 6 Elec- Fe.sup.2+ 300 300 300 300 300 300 tro- FeSO.sub.4, lyte.sup.(a) (NH.sub.4).sub.2, SO.sub.4, 6H.sub.2O Fe.sup.2+ 40 40 40 40 40 40 FeCl.sub.2, 4H.sub.2O sulfuric 0.12 0.12 0.12 0.12 qs.sup.(i) qs.sup.(i) acid H.sub.2SO.sub.4 citric acid 1.2 1.2 1.2 C.sub.6H.sub.8O.sub.7 L ascorbic 3 3 3 acid C.sub.6H.sub.8O.sub.6 boric acid 40 40 H.sub.3BO.sub.3 borane 1.8 1.8 dimethyl- amine (CH.sub.3).sub.2 NH BH.sub.3 Sodium 3 3 hypophos- phite H.sub.2Na.sub.2PO.sub.2 aluminum 5 5 sulfate Al.sub.2(SO.sub.4).sub.3, 18H.sub.2O electrolyte 4.5-5 4.5-5 4.5-5 4.5-5 1-2 1-2 pH Current 5 1 5 5 5 5 density (A/dm.sup.2) .sup.(i)qs: quantity sufficient to obtain the pH of the electrolyte

(55) TABLE-US-00002 TABLE 2 Properties of the binders according to examples 1-6. Examples (binder) 4 6 1 2 3 Fe + 5 Fe + Fe Fe + C Fe + B C + B Fe + P C + P Addition % O 5% 2% <2% <2% <3% <3% elements % C 1% 1% 1% % B 0.5% 0.5% % P 4% 4% Hv hardness 200-400 600 300 600 500 600 Brittleness Average Strong Low Low Low Low Corrosion Strong Strong Strong Strong Low Low

(56) The percentages of the addition elements are expressed with respect to the mass of the binder on the steel core of the abrasive wire.