PREPARATION METHOD OF NIOBIUM DISELENIDE FILM WITH ULTRA-LOW FRICTION AND LOW ELECTRICAL NOISE UNDER SLIDING ELECTRICAL CONTACT IN VACUUM

Abstract

The present disclosure relates to a preparation method of a niobium diselenide (NbSe.sub.2) film with ultra-low friction and low electrical noise under sliding electrical contact in vacuum. The method uses a direct current (DC) closed field magnetron sputtering method for preparation. Through process design of low deposition pressure and low sputtering energy, on one hand, a purity of an NbSe.sub.2 sputtered product is kept, generation of interference phases such as NbSe.sub.3 is avoided, and electrical conductivity of the sputtered NbSe.sub.2 film is greatly improved, and on the other hand, a nanocrystalline/amorphous superlattice composite structure is formed, and excellent mechanical and lubricating properties are achieved. Under sliding electrical contact in vacuum, compared with those of a common electroplated gold coating, a friction coefficient of the film is reduced to 0.02 from 0.25, a wear life is prolonged by at least 7 times, and the electrical noise is reduced by about 50%.

Claims

1. A preparation method of a niobium diselenide (NbSe.sub.2) film with ultra-low friction and low electrical noise under sliding electrical contact in vacuum, wherein the method uses a direct current (DC) closed field magnetron sputtering method for preparation; and through process design of low deposition pressure and low sputtering energy, the method comprises the following steps: (1) placing a to-be-coated substrate with a clean surface on a sample holder in a coating chamber, and conducting argon plasma cleaning and etching to remove residual impurities and pollutants on the surface of the substrate; (2) preparing a titanium (Ti) transition layer on the surface of the substrate by taking argon as a sputtering gas and a titanium target as a sputtering target to improve film-substrate bonding strength between the substrate and the NbSe.sub.2 film; and (3) preparing an NbSe.sub.2 lubricating layer by taking argon as a sputtering gas and an NbSe.sub.2 target as a sputtering target.

2. The preparation method of an NbSe.sub.2 film with ultra-low friction and low electrical noise under sliding electrical contact in vacuum according to claim 1, wherein in step (1), a background vacuum pressure of a vacuum cavity of the coating chamber is lower than 3×10.sup.−3 Pa; and a cleaning pressure is stabilized at 0.8 to 2.0 Pa, and the cleaning is conducted at a negative substrate bias voltage of −400 to −800 V.

3. The preparation method of an NbSe.sub.2 film with ultra-low friction and low electrical noise under sliding electrical contact in vacuum according to claim 1, wherein in step (2), a purity of the Ti target is higher than 99.8%; the titanium transition layer is prepared at a sputtering pressure of 0.1 to 0.5 Pa, a target sputtering power of 0.5 to 10 W/cm.sup.2, and a negative substrate bias voltage of −50 to −400 V; and the Ti layer has a thickness of 0.1 to 1 um.

4. The preparation method of an NbSe.sub.2 film with ultra-low friction and low electrical noise under sliding electrical contact in vacuum according to claim 1, wherein in step (3), a purity of the NbSe.sub.2 target is higher than 99.9%; the lubricating layer is prepared at a sputtering pressure of 0.04 to 0.3 Pa, a target sputtering power of 0.2 to 1 W/cm.sup.2, and a negative substrate bias voltage of −50 to −400 V; and the NbSe.sub.2 layer has a thickness of 1 to 5 um.

5. The preparation method of an NbSe.sub.2 film with ultra-low friction and low electrical noise under sliding electrical contact in vacuum according to claim 1, wherein the to-be-coated substrate is made of copper, aluminum, titanium alloy, or steel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 is a schematic diagram of a DC closed field magnetron sputtering deposition system for an NbSe.sub.2 lubricating film;

[0020] FIG. 2 shows an XRD pattern of the NbSe.sub.2 lubricating film prepared by the present disclosure;

[0021] FIG. 3 shows a HRTEM photograph of the NbSe.sub.2 lubricating film prepared by the present disclosure;

[0022] FIG. 4A shows a friction curve comparison between the NbSe.sub.2 lubricating film prepared by the present disclosure and a current electroplated gold coating;

[0023] FIG. 4B shows a contact voltage comparison between the NbSe.sub.2 lubricating film prepared by the present disclosure and a current electroplated gold coating; and

[0024] FIG. 4C shows a contact electrical noise comparison between the NbSe.sub.2 lubricating film prepared by the present disclosure and a current electroplated gold coating.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Example 1

[0025] 1) Argon plasma cleaning of to-be-coated sample: a copper slip ring with a clean surface and copper, aluminum, 9Cr18, and TC4 test blocks were placed on a sample holder in a coating chamber, and an air pressure in the vacuum cavity was pumped to be no more than 3.0×10.sup.−3 Pa. High-purity argon was introduced till a pressure of 1.8 Pa. A negative bias power supply was turned on. A voltage was adjusted −600 V. Argon plasma bombardment cleaning was conducted for 20 min to remove residual impurities and pollutants on the surface of the substrate.

[0026] 2) Deposition of titanium (Ti) transition layer: an argon flow was adjusted to maintain the pressure in the chamber at 0.1 Pa. A DC sputtering power supply for a titanium target and a negative bias power supply were turned on. A sputtering power density of the titanium target was adjusted to 0.3 W/cm.sup.2. A negative bias voltage was −50 V. Deposition was conducted with a thickness of 0.2 μm.

[0027] 3) Deposition of NbSe.sub.2 conductive lubricating layer: the argon flow was adjusted to maintain the pressure in the chamber at 0.05 Pa. The DC sputtering power supply for the titanium target was turned off. A DC sputtering power supply for the NbSe.sub.2 target was turned on. An NbSe.sub.2 target sputtering power was adjusted to 0.3 W/cm.sup.2. A negative bias voltage of the negative bias power supply was adjusted to −50 V. After deposition with a thickness of 2 μm, Ar gas was filled in place for natural cooling. When the temperature was stabilized to a room temperature, vacuum was released to take out the sample.

[0028] 4) Film performance: the film had a static resistivity of 8.6×10.sup.−6 Ω.Math.cm and a friction coefficient of 0.025 under vacuum current-carrying conditions, and a wear life of 100,000 cycles without failure.

Example 2

[0029] 1) Argon plasma cleaning and etching of to-be-coated sample: a copper slip ring with a clean surface and copper, aluminum, 9Cr18, and TC4 test blocks were placed on a sample holder in a coating chamber, and an air pressure in the vacuum cavity was pumped to be no more than 3.0×10.sup.−3 Pa. High-purity argon was introduced till a pressure of 0.8 Pa. A negative bias power supply was turned on. A voltage was adjusted −800 V. Argon plasma bombardment cleaning was conducted for 30 min to remove residual impurities and pollutants on the surface of the substrate.

[0030] 2) Deposition of titanium transition layer: an argon flow was adjusted to maintain the pressure in the chamber at 0.3 Pa. A DC sputtering power supply for a titanium target and a negative bias power supply were turned on. A sputtering power density of the titanium target was adjusted to 1.5 W/cm.sup.2. A negative bias voltage was −200 V. Deposition was conducted with a thickness of 0.4 μm.

[0031] 3) Deposition of NbSe.sub.2 conductive lubricating layer: the argon flow was adjusted to maintain the pressure in the chamber at 0.15 Pa. The DC sputtering power supply for the titanium target was turned off. A DC sputtering power supply for the NbSe.sub.2 target was turned on. An NbSe.sub.2 target sputtering power was adjusted to 0.5 W/cm.sup.2. A negative bias voltage of the negative bias power supply was adjusted to −150 V. After deposition with a thickness of 3.5 μm, Ar gas was filled in place for natural cooling. When the temperature was stabilized to a room temperature, vacuum was released to take out the sample.

[0032] 4) Film performance: the film had a static resistivity of 7.8×10.sup.−6 Ω.Math.cm and a friction coefficient of 0.022 under vacuum current-carrying conditions, and a wear life of 100,000 cycles without failure.

Example 3

[0033] 1) Argon plasma cleaning and etching of to-be-coated sample: a copper slip ring with a clean surface and copper, aluminum, 9Cr18, and TC4 test blocks were placed on a sample holder in a coating chamber, and an air pressure in the vacuum cavity was pumped to be no more than 3.0×10.sup.−3 Pa. High-purity argon was introduced till a pressure of 1.2 Pa. A negative bias power supply was turned on. A voltage was adjusted −400 V. Argon plasma bombardment cleaning was conducted for 40 min to remove residual impurities and pollutants on the surface of the substrate.

[0034] 2) Deposition of titanium transition layer: an argon flow was adjusted to maintain the pressure in the chamber at 0.5 Pa. A DC sputtering power supply for a titanium target and a negative bias power supply were turned on. A sputtering power density of the titanium target was adjusted to 8.5 W/cm.sup.2. A negative bias voltage was −350 V. Deposition was conducted with a thickness of 0.8 μm.

[0035] 3) Deposition of NbSe.sub.2 conductive lubricating layer: the argon flow was adjusted to maintain the pressure in the chamber at 0.3 Pa. The DC sputtering power supply for the titanium target was turned off. A DC sputtering power supply for the NbSe.sub.2 target was turned on. An NbSe.sub.2 target sputtering power was adjusted to 0.9 W/cm.sup.2. A negative bias voltage of the negative bias power supply was adjusted to −350 V. After deposition with a thickness of 4.5 μm, Ar gas was filled in place for natural cooling. When the temperature was stabilized to a room temperature, vacuum was released to take out the sample.

[0036] 4) Film performance: the film had a static resistivity of 9.2×10.sup.−6 Ω.Math.cm and a friction coefficient of 0.029 under vacuum current-carrying conditions, and a wear life of 100,000 cycles without failure.