CVD (Chemical Vapor Deposition) coating applicable to microporous wire-drawing die and preparation method of CVD coating

Abstract

The invention discloses a CVD (chemical vapor deposition) coating applicable to a microporous wire-drawing die and a preparation method of the CVD coating, and relates to the technical field of CVD coatings. A composite coating is deposited in a microporous wire drawing die through a CVD method, and the composite coating is sequentially provided with TiN / Ti (C, N) / beta-SiC / aluminum oxide from inside to outside; wherein TiN is used as a coating in direct contact with a microporous wire-drawing die substrate, and the main purpose of TiN is to improve the bonding strength between the coating and the substrate and prevent the coating from falling off due to cracks generated by stress change caused by different thermal expansion coefficients between the substrate and the coating.

Description

Technical Field

[0001] The invention relates to the technical field of synchronous preparation of CVD coatings, in particular to a CVD coating suitable for a microporous wire drawing die and a preparation method thereof. Background Art

[0002] CVD coating of microporous wire drawing dies refers to the formation of a layer of diamond or other hard material coating on the surface of the microporous wire drawing die through chemical vapor deposition (CVD) technology. This coating technology can significantly improve the hardness, wear resistance, corrosion resistance and service life of the wire drawing die, and is particularly suitable for the drawing of small wires and wires. CVD technology is a method of converting gaseous substances into solid substances through chemical reactions in a vacuum or inert gas environment and depositing them on the surface of the substrate. In the CVD coating process of microporous wire drawing dies, commonly used raw materials include hydrogen, methane, acetone, etc. These gases react chemically at high temperatures to form coatings of diamond or other hard materials.

[0003] CVD coating can significantly improve the hardness and wear resistance of the wire drawing die, enabling it to withstand higher drawing forces and longer use: the coating can protect the base material from wear and corrosion, thereby extending the service life of the wire drawing die and improving the surface quality of the drawn product. Summary of the invention

[0004] The object of the present invention is to provide a CVD coating suitable for a microporous wire drawing die and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for preparing a CVD coating suitable for a microporous wire drawing die. The CVD coating is TiN / Ti(C, N) / SiC-nano diamond / alumina in order from the surface of a microporous wire drawing die substrate outward.

[0007] As an optimization, the total thickness of the CVD coating is 15-25 μm, including TiN (0.5-1 μm) / Ti(C, N) (4-7 μm) / SiC-nanodiamond (2-4 μm) / aluminum oxide (10-15 μm).

[0008] As an optimization, the TiN layer is prepared by chemical vapor deposition, the deposition temperature is 850-950° C., the deposition pressure is 20-40 mbar, and the reaction gases are nitrogen, hydrogen and titanium tetrachloride;

[0009] 2TiCl4+N2+4H2→2TiN+8HCl

[0010] The reaction process is shown in the above formula.

[0011] As an optimization, the Ti(C, N) layer is prepared by chemical vapor deposition, with a deposition temperature of 800-900° C., a deposition pressure of 5-20 kPa, and reaction gases of titanium tetrachloride, acetonitrile and hydrogen;

[0012] 2TiCl4+2CH4+N2→2TiCN+8HCl

[0013] The reaction process is shown in the above formula.

[0014] As an optimization, the SiC-nano diamond layer is prepared by chemical vapor deposition, the deposition temperature is 830-850° C., the deposition pressure is 5-9 kPa, the reaction gases are tetramethylsilane, hydrogen and methane, and the hardness of the SiC-nano diamond layer is 30-35 GPa.

[0015] As an optimization, the aluminum oxide layer is prepared by chemical vapor deposition, the deposition temperature is 1000-1100°C, the deposition pressure is 30-40kpa, and the reaction gas is gaseous aluminum halide; the gaseous aluminum halide is generated by reacting hydrogen chloride activation gas with pure aluminum at a temperature of 300-350°C.

[0016] As an optimization, before depositing the TiN layer, the microporous wire drawing die substrate is immersed in acetone, deionized water and anhydrous ethanol in sequence for ultrasonic cleaning for 30 to 40 minutes and then taken out. After ultrasonic cleaning, it is immersed in Murakami reagent and allowed to stand for 10 to 15 minutes, then taken out and washed with deionized water for 2 to 3 times, then immersed in Caro's acid reagent and allowed to stand for 1 to 2 minutes, then taken out, washed with deionized water for 2 to 3 times, and dried for use.

[0017] As an optimization, the Murakami reagent is prepared by mixing potassium ferrocyanide, potassium hydroxide and deionized water in a mass ratio of 1:1-1.2:20-22; the Caro's acid reagent is prepared by mixing sulfuric acid and hydrogen peroxide in a volume ratio of 1:10-12.

[0018] As an optimization, the microporous wire drawing die substrate is pre-processed with crystal planting before depositing the SiC-nano diamond layer. The microporous wire drawing die substrate deposited with the TiN layer and the Ti(C, N) layer is immersed in a diamond suspension, and then taken out and dried after ultrasonic vibration for 30 minutes for use.

[0019] A CVD coating suitable for a microporous wire drawing die is prepared by using any of the above preparation methods.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0021] The present application deposits a composite coating in a microporous wire drawing die by a CVD method, wherein the composite coating is sequentially arranged from the inside to the outside as TiN / Ti(C, N) / β-SiC / alumina; wherein TiN is used as a coating directly in contact with the substrate of the microporous wire drawing die, and its main purpose is to improve the bonding strength between the coating and the substrate, and to avoid stress changes and cracks caused by the difference in thermal expansion coefficients between the substrate and the coating, so as to cause the coating to fall off;

[0022] The second layer is a Ti(C, N) layer, which is used as the second layer to improve the overall toughness of the coating. Since the microstructure of the coating is finer and columnar, and there is no looseness, pores and dendrites in the coating, the cap coating can effectively reduce the diffusion and outward penetration of the Co phase on the substrate surface, which affects the mechanical strength of the diamond coating. In the process of preparing the coating, the substrate surface is pretreated with acid and alkali to eliminate the influence of Co. First, alkali solution is used for treatment, and the tungsten carbide grains on the substrate surface are etched by alkali solution to enhance the roughness of the substrate surface and expose the surface Co phase as much as possible. Then, acid solution is used for de-Co treatment, so that the substrate surface is in a state without Co phase.

[0023] The third layer uses a silicon carbide and diamond composite layer, which mainly serves as a transition layer. On the one hand, it improves the bonding strength of the membrane-substrate interface. On the other hand, the physical properties of the cover layer interface and the diamond interface are similar, which can effectively reduce the mismatch between the coatings due to thermal expansion coefficients and elastic moduli. Caused by cracks; the mechanical properties of the composite coating can be regulated within a wide range according to the content of the two phases in the structure, thereby optimizing the membrane-substrate interface bonding strength to the greatest extent; and the outermost layer uses alumina to improve the oxidation resistance and thermal corrosion performance. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] Example 1

[0026] The microporous wire drawing die substrate CVD coating is sequentially deposited on the substrate surface, and the preparation method is as follows:

[0027] The TiN layer was prepared by chemical vapor deposition at a deposition temperature of 850°C, a deposition pressure of 20 mbar, and reaction gases of nitrogen, hydrogen, and titanium tetrachloride; TiN (0.5 μm);

[0028] The Ti(C, N) layer was prepared by chemical vapor deposition at a temperature of 800°C and a pressure of 5 kPa.

[0029] The reaction gases are titanium tetrachloride, acetonitrile and hydrogen; Ti(C,N) (4 μm);

[0030] The SiC-nanodiamond layer was prepared by chemical vapor deposition, with a deposition temperature of 830°C, a deposition pressure of 5 kPa, and reaction gases of tetramethylsilane, hydrogen, and methane; SiC-nanodiamond (2 μm);

[0031] The aluminum oxide layer is prepared by chemical vapor deposition, with a deposition temperature of 1000°C, a deposition pressure of 30 kPa, and a reaction gas of gaseous aluminum halide; the gaseous aluminum halide is activated by hydrogen chloride gas and reacts with pure aluminum at a temperature of 300°C to generate gaseous aluminum halide (10 μm).

[0032] Example 2

[0033] The microporous wire drawing die substrate CVD coating is sequentially deposited on the substrate surface, and the preparation method is as follows:

[0034] The TiN layer was prepared by chemical vapor deposition at a deposition temperature of 900°C, a deposition pressure of 30 mbar, and reaction gases of nitrogen, hydrogen, and titanium tetrachloride; TiN (0.8 μm);

[0035] The Ti(C, N) layer was prepared by chemical vapor deposition at a temperature of 850°C and a pressure of 10 kPa.

[0036] The reaction gases are titanium tetrachloride, acetonitrile and hydrogen; Ti(C,N)(6μm);

[0037] The SiC-nanodiamond layer was prepared by chemical vapor deposition, with a deposition temperature of 840°C, a deposition pressure of 7 kPa, and reaction gases of tetramethylsilane, hydrogen, and methane; SiC-nanodiamond (3 μm);

[0038] The aluminum oxide layer is prepared by chemical vapor deposition, with a deposition temperature of 1050°C, a deposition pressure of 35 kPa, and a reaction gas of gaseous aluminum halide; the gaseous aluminum halide is activated by hydrogen chloride gas and reacts with pure aluminum at a temperature of 325°C to generate gaseous aluminum halide (12 μm).

[0039] Example 3

[0040] The microporous wire drawing die substrate CVD coating is sequentially deposited on the substrate surface, and the preparation method is as follows:

[0041] The TiN layer was prepared by chemical vapor deposition at a temperature of 950°C, a pressure of 40 mbar, and reaction gases of nitrogen, hydrogen, and titanium tetrachloride; TiN (1 μm);

[0042] The Ti(C, N) layer was prepared by chemical vapor deposition at a temperature of 900°C and a pressure of 20 kPa.

[0043] The reaction gases are titanium tetrachloride, acetonitrile and hydrogen; Ti(C,N)(7μm);

[0044] The SiC-nanodiamond layer was prepared by chemical vapor deposition at a deposition temperature of 850°C, a deposition pressure of 9 kPa, and reaction gases of tetramethylsilane, hydrogen, and methane; SiC-nanodiamond (4 μm);

[0045] The aluminum oxide layer is prepared by chemical vapor deposition, with a deposition temperature of 1100°C, a deposition pressure of 40 kPa, and a reaction gas of gaseous aluminum halide; the gaseous aluminum halide is activated by hydrogen chloride gas and reacts with pure aluminum at a temperature of 350°C to generate gaseous aluminum halide (15 μm).

[0046] Example 4

[0047] The microporous wire drawing die substrate CVD coating is sequentially deposited on the substrate surface, and the preparation method is as follows:

[0048] The Ti(C, N) layer was prepared by chemical vapor deposition at a temperature of 850°C and a pressure of 10 kPa.

[0049] The reaction gases are titanium tetrachloride, acetonitrile and hydrogen; Ti(C,N)(6μm);

[0050] The SiC-nanodiamond layer was prepared by chemical vapor deposition, with a deposition temperature of 840°C, a deposition pressure of 7 kPa, and reaction gases of tetramethylsilane, hydrogen, and methane; SiC-nanodiamond (3 μm);

[0051] The aluminum oxide layer is prepared by chemical vapor deposition, with a deposition temperature of 1050°C, a deposition pressure of 35 kPa, and a reaction gas of gaseous aluminum halide; the gaseous aluminum halide is activated by hydrogen chloride gas and reacts with pure aluminum at a temperature of 325°C to generate gaseous aluminum halide (12 μm).

[0052] Example 5

[0053] The microporous wire drawing die substrate CVD coating is sequentially deposited on the substrate surface, and the preparation method is as follows:

[0054] The TiN layer was prepared by chemical vapor deposition at a deposition temperature of 900°C, a deposition pressure of 30 mbar, and reaction gases of nitrogen, hydrogen, and titanium tetrachloride; TiN (0.8 μm);

[0055] The SiC-nanodiamond layer was prepared by chemical vapor deposition, with a deposition temperature of 840°C, a deposition pressure of 7 kPa, and reaction gases of tetramethylsilane, hydrogen, and methane; SiC-nanodiamond (3 μm);

[0056] The aluminum oxide layer is prepared by chemical vapor deposition, with a deposition temperature of 1050°C, a deposition pressure of 35 kPa, and a reaction gas of gaseous aluminum halide; the gaseous aluminum halide is activated by hydrogen chloride gas and reacts with pure aluminum at a temperature of 325°C to generate gaseous aluminum halide (12 μm).

[0057] Example 6

[0058] The microporous wire drawing die substrate CVD coating is sequentially deposited on the substrate surface, and the preparation method is as follows:

[0059] The TiN layer was prepared by chemical vapor deposition at a deposition temperature of 900°C, a deposition pressure of 30 mbar, and reaction gases of nitrogen, hydrogen, and titanium tetrachloride; TiN (0.8 μm);

[0060] The Ti(C, N) layer was prepared by chemical vapor deposition at a deposition temperature of 850°C, a deposition pressure of 10 kPa, and reaction gases of titanium tetrachloride, acetonitrile and hydrogen; Ti(C, N) (6 μm);

[0061] The aluminum oxide layer is prepared by chemical vapor deposition, with a deposition temperature of 1050°C, a deposition pressure of 35 kPa, and a reaction gas of gaseous aluminum halide; the gaseous aluminum halide is activated by hydrogen chloride gas and reacts with pure aluminum at a temperature of 325°C to generate gaseous aluminum halide (12 μm).

[0062] Example 7

[0063] The microporous wire drawing die substrate CVD coating is sequentially deposited on the substrate surface, and the preparation method is as follows:

[0064] The TiN layer was prepared by chemical vapor deposition at a deposition temperature of 900°C, a deposition pressure of 30 mbar, and reaction gases of nitrogen, hydrogen, and titanium tetrachloride; TiN (0.8 μm);

[0065] The Ti(C, N) layer was prepared by chemical vapor deposition at a temperature of 850°C and a pressure of 10 kPa.

[0066] The reaction gases are titanium tetrachloride, acetonitrile and hydrogen; Ti(C,N)(6μm);

[0067] The SiC-nano-diamond layer was prepared by chemical vapor deposition, with a deposition temperature of 840° C., a deposition pressure of 7 kPa, and reaction gases of tetramethylsilane, hydrogen, and methane; SiC-nano-diamond (3 μm).

[0068] Test Example 1

[0069] The film-substrate bonding strength, anti-oxidation temperature, hardness and friction coefficient of each CVD coating in Examples 1 to 7 are shown in Table 1.

[0070] Table 1 Test results

[0071]

[0072] From the comparison of the experimental data of Examples 1 to 7 in Table 1, it can be found that the CVD coatings in Examples 1 to 3 all perform well in various indicators;

[0073] The film-substrate bonding strength in Example 4 is the lowest, mainly because the contact layer with the substrate is a Ti (C, N) layer, which is not tightly bonded to the substrate during the deposition process, resulting in poor final test results;

[0074] Although the film-substrate bonding strength is good in Examples 5 and 6, since there is only one layer between the SiC-nanodiamond layer and the substrate during the deposition process, the coating cannot effectively prevent the Co phase on the substrate surface from diffusing outward, resulting in limited deposition effect of the final SiC-nanodiamond layer, which reduces the final performance of the coating; and in Example 7, since the final aluminum oxide layer is not deposited, the hardness of the final coating is greatly reduced.

[0075] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing a CVD coating suitable for a microporous wire drawing die, characterized in that: The CVD coating is TiN / Ti(C, N) / SiC-nano diamond / aluminum oxide in order from the surface of the microporous wire drawing die substrate to the outside.

2. The method for preparing a CVD coating suitable for a microporous wire drawing die according to claim 1, characterized in that: The total thickness of the CVD coating is 15-25 μm, including TiN (0.5-1 μm) / Ti (C, N) (4-7 μm) / SiC-nano diamond (2-4 μm) / aluminum oxide (10-15 μm).

3. The method for preparing a CVD coating suitable for a microporous wire drawing die according to claim 1, characterized in that: The TiN layer is prepared by chemical vapor deposition, the deposition temperature is 850-950° C., the deposition pressure is 20-40 mbar, and the reaction gases are nitrogen, hydrogen and titanium tetrachloride; 2TiCl4+N2+4H2→2TiN+8HCl The reaction process is shown in the above formula.

4. The method for preparing a CVD coating suitable for a microporous wire drawing die according to claim 1, characterized in that: The Ti(C, N) layer is prepared by chemical vapor deposition, the deposition temperature is 800-900° C., the deposition pressure is 5-20 kPa, and the reaction gases are titanium tetrachloride, acetonitrile and hydrogen; 2TiCl4+2CH4+N2→2TiCN+8HCl The reaction process is shown in the above formula.

5. The method for preparing a CVD coating suitable for a microporous wire drawing die according to claim 1, characterized in that: The SiC-nano diamond layer is prepared by chemical vapor deposition, the deposition temperature is 830-850° C., the deposition pressure is 5-9 kPa, the reaction gas is tetramethylsilane, hydrogen and methane, and the hardness of the SiC-nano diamond layer is 30-35 GPa.

6. The method for preparing a CVD coating suitable for a microporous wire drawing die according to claim 1, characterized in that: The aluminum oxide layer is prepared by chemical vapor deposition, the deposition temperature is 1000-1100° C., the deposition pressure is 30-40 kPa, and the reaction gas is gaseous aluminum halide.

7. The method for preparing a CVD coating suitable for a microporous wire drawing die according to claim 1, characterized in that: Before depositing the TiN layer, the microporous wire drawing die substrate is immersed in acetone, deionized water and anhydrous ethanol in sequence for ultrasonic cleaning for 30 to 40 minutes and then taken out. After ultrasonic cleaning, it is immersed in Murakami reagent and allowed to stand for 10 to 15 minutes, then taken out and washed with deionized water for 2 to 3 times, then immersed in Caro's acid reagent and allowed to stand for 1 to 2 minutes, then taken out, washed with deionized water for 2 to 3 times, and dried for use.

8. The method for preparing a CVD coating suitable for a microporous wire drawing die according to claim 1, characterized in that: The Murakami reagent is prepared by mixing potassium ferrocyanide, potassium hydroxide and deionized water in a mass ratio of 1:1-1.2:20-22; the Caro's acid reagent is prepared by mixing sulfuric acid and hydrogen peroxide in a volume ratio of 1:10-12.

9. The method for preparing a CVD coating suitable for a microporous wire drawing die according to claim 1, characterized in that: The microporous wire drawing die substrate is pre-processed with crystal planting before depositing the SiC-nano diamond layer. The microporous wire drawing die substrate with the TiN layer and the Ti(C, N) layer deposited is immersed in a diamond suspension, and then ultrasonically vibrated for 30 minutes before being taken out and dried for later use.

10. A CVD coating suitable for a microporous wire drawing die, characterized in that: The compound is prepared by any one of the preparation methods in claims 1 to 9.

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