KR100762198B1 - Coating material and thereof coating method with superhard and high lubrication - Google Patents

Abstract

A coating material having high hardness and high lubricating property is provided to solve the mechanical property-related problems occurring in conventional hard thin films, and to obtain an eco-friendly coating film having good wear resistance and improved lifespan. A coating material having high hardness and high lubricating property is vacuum deposited on a matrix(100) of a mold or lubricating article to form a thin film layer(300), wherein the coating material comprises 42.9-75.8 wt% of Cr, 6.0-38.4 wt% of Zr, and 18.2-20.7 wt% of N. The thin film layer has a thickness of 2-6 micrometers. The thin film layer optionally further comprises an intermediate layer(200) formed of Cr or CrN between the matrix and the thin film layer to relieve residual stress.

Description

High hardness, high lubricity coating material and its coating method {COATING MATERIAL AND THEREOF COATING METHOD WITH SUPERHARD AND HIGH LUBRICATION}

1 is an exemplary schematic configuration diagram of a coating apparatus according to the present invention;

2 is an enlarged view illustrating main parts of FIG. 1 as two targets according to the present invention;

3 is an exemplary schematic configuration view showing a coating apparatus in the case of one target according to the present invention;

4 is a structural view of the coating layer by the coating material according to the present invention;

5 and 6 is an exemplary cross-sectional structure and a surface photograph of the high lubricating thin film coated with a coating material according to the present invention,

7 is a graph of test results according to an embodiment of the present invention.

♧ description of the symbols for the main parts of the drawing ♧

10..Vacuum chamber 20 .... Vacuum pump

30 .... Cr Deposition Source 40 .... Zr Deposition Source

50 .... Rotating jig 60 .... Shutter

70 .... Flow control part

The present invention relates to a high hardness, high lubricity coating material and a coating method thereof, and more particularly, the temperature of the DLC (Diamond Like Carbon) thin film represented by the limit of the hard thin film made of a conventional high hardness compound coating and the lubricating thin film and The present invention relates to a high hardness, high lubricity coating material and a method of coating the same to overcome the limitations on humidity and to maintain environmentally friendly and superior mechanical properties.

Typically, gas nitriding and carburization, wet plating, and the like have been used as metal surface treatment techniques for improving mechanical properties of components, particularly durability.

However, as the application environment is severe along with the refinement and miniaturization of parts, such surface treatment technology cannot be applied. Especially, in the case of the wet plating method, the use of the surface treatment causes severe environmental problems. There is a situation.

Accordingly, studies on plasma coatings that are more environmentally friendly and exhibit better mechanical properties have been actively conducted worldwide. Until now, TiN, TiC, Ti (C, N), (Ti, Al) N, CrN, ZrN, etc. Hard compound coatings have been applied in many businesses to improve the life and productivity of materials. However, this also exposes many limitations of the existing plasma coating method due to the complicated use conditions of the product and the severe use conditions.

In addition, high hardness compounds have low wear characteristics (abrasion rate) due to their high hardness, but due to their high hardness and high coefficient of friction, they are known to cause a lot of wear of the counterpart.

In order to solve these problems, DLC (Diamond like carbon) coating method, which can be used in high lubrication conditions because of low wear rate and low friction coefficient, has been proposed and used, but the wear characteristics of DLC thin films have a Due to a lot of constraints on temperature caused a sharp drop in effectiveness.

For example, in the case of DLC thin film, the coefficient of friction increased from 0.2 at room temperature to about 3 times as high as 0.6 at 300 ℃ or higher, and the use time of DLC coated products was 3 times higher in the humid atmosphere than in the dry atmosphere depending on the humidity. It has been found that the tendency to decrease by as much as 10 times.

Therefore, there is a continuous need to study a variety of new types of thin films that can compensate for the drawbacks of surface treatment techniques as described above.

However, no effective technology has been specifically provided so far, and it remains in the research stage.

The present invention has been made to solve the above problems in view of the above-mentioned prior art, by adding zirconium to the chromium nitride thin film to overcome the limitations of the mechanical properties of the existing hard thin film and at the same time the effect of temperature and humidity of the DLC thin film Its main purpose is to provide a high hardness, high lubrication coating material and its coating method that overcome the limitations of the reduction of properties and provide both abrasion resistance and high lubrication activity, while being environmentally friendly and long life.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment according to the present invention.

First, the present invention is to obtain a high lubricity by increasing the hardness and lower the surface roughness (Roughness) through the thin film synthesis by adding Zr to CrN, and also maximize the plasma density and ionization rate by adopting the asymmetric magnetron sputtering method The schematic process principle is as follows.

That is, the magnet is mounted on the cathode on which the material to be coated is applied as a target to apply a magnetic field in a direction parallel to the target surface to focus the electrons and to rotate the electrons in the vicinity thereof so that the plasma is very close to the target surface. As a result, the plasma density and the ionization rate are increased by this phenomenon, and as a result, the sputtering rate is also improved while increasing the discharge current by the mass produced ions.

Therefore, the number of ions colliding with the target is increased, resulting in an increase in deposition rate.

At this time, it is preferable that the magnets equipped with the two sputtering deposition sources are installed with different poles from each other to form a magnetic field of the closed circuit.

In addition, it is preferable to use Cr having a purity of 99.9% and Zr having a purity of 99.9% as targets for use.

FIG. 1 is an exemplary schematic configuration diagram of a coating apparatus according to the present invention, and FIG. 2 is an enlarged view of main parts of FIG. 1 in the case of two targets.

As shown in Figure 1 and 2, there is provided a vacuum chamber 10, the coating operation is performed therein, one side of the vacuum chamber 10 is a suitable vacuum degree, such as 10 ^-3 ~ 10 ^-5 Torr or less It is provided with a vacuum pump 20 that can be dropped in, the inside of the vacuum chamber 10 is formed at a certain angle (40 ~ 50 °) with each other Cr Cr deposition source for Cr thin film synthesis and Zr thin film synthesis (30) ) And Zr deposition source 40 is provided.

At this time, the Cr and Zr deposition sources 30 and 40 are asymmetrically installed with each other as described above as the magnetron sputtering deposition source.

That is, as shown in Figure 2, the magnetic pole of the Cr deposition source 30, which is a magnetron is arranged in the SNS, while the Cr target 32 is attached to the lower surface, while the magnetic pole of the Zr deposition source 40, which is a magnetron Is disposed in the NSN, it is preferable that the Zr target 42 is attached to the structure made of a structure.

In addition, a rotary jig 50 having a structure capable of being moved up and down while being able to move up and down to maintain a predetermined distance with the Cr deposition source 30 and the Zr deposition source 40 is formed at the inner center of the vacuum chamber 10. Is installed, the specimen (S) is seated on the upper surface of the rotary jig 50, the shutter 60 is provided between the specimen (S) and the Cr and Zr deposition sources (30, 40).

At this time, the rotary jig 50 should be provided in a vacuum and insulated state to apply a direct current and a pulsed DC bias voltage (-), and the shutter 60 has a foreign material on the target surface to stabilize the plasma. The specimen surface is prevented from being deposited during removal.

In this case, the DC bias voltage is a thin film is deposited without bias, but in order to increase the deposition rate of the thin film (+) ions such as Cr ⁺ from the target to be deposited on the specimen to be better, at this time Direct current and pulsed DC bias are preferred as a means to keep the bias constant, and a -50 to -200V range is particularly preferable because when it is lower than -200V, there is no effect of increasing deposition rate and when it is higher than -50V (+ This is because the ions accelerate rapidly and rather impede thin film deposition by ion bombardment in the substrate.

In addition, one side of the vacuum chamber 10 is provided with a flow rate control unit 70 for adjusting the flow rate of nitrogen or argon gas which is an atmosphere gas used in the synthesis of a thin film.

Through such a coating apparatus, the surface of the specimen (S) can obtain a thin film of 42.9 ~ 75.8Cr-6.0 ~ 38.4Zr-18.2 ~ 20.7N component composition by weight of the present invention coating material.

Meanwhile, the present invention may produce a thin film of a desired composition by using one magnetron sputtering deposition source, and FIG. 3 shows such an example.

That is, Figure 3 is an exemplary view showing a case of one coating device according to the present invention, a pair of Cr to be opposed to each other on both side walls of the vacuum chamber 10 to maintain a proper degree of vacuum by the vacuum pump 20 -The Zr target 82 is attached to the Cr-Zr deposition source 80, a rotating jig (not shown) rotatable by the rotating motor (M) is installed in the inner center of the vacuum chamber 10, this rotation The specimen (S) is fixed on the jig, a bias source 90 for supplying power to the Cr-Zr deposition source 80 is provided, the internal magnetic field and the external magnetic field by the power supply of the bias source (90) Plasma region (P) as close to the specimen (S) by varying the intensity of the Cr, Zr particles (including ions, atoms, molecules, etc.) separated from the Cr-Zr target 82 is uniform in the specimen (S) It is possible to have a high deposition rate while being deposited.

Here, the bias source 90 is the same as in the above examples of FIGS.

Through this deposition process, the present invention coating material (thin film) as shown in FIG. 4 can be obtained.

That is, Figure 4 shows the structure of the coating material (thin film) according to the present invention, the coating material (thin film) of the present invention as shown in the intermediate layer 200 for improving the adhesion while relieving stress on the base metal material 100 of the metal material And a Cr-Zr-N layer 300 having a thickness of several μm having high hardness and high lubrication thereon is deposited to form a laminate.

At this time, the intermediate layer 200 is preferably mainly composed of a Cr layer or a CrN layer, the thickness is preferably 0.5 ~ 1.5㎛, the reason is that if the thin film is deposited directly on the base material without the intermediate layer 200, the residual stress is Because it is generated to solve this problem, if the thickness is too thick (more than 1.5㎛), the physical properties of the thin film are too low, and if it is too thin (0.5㎛ or less), the residual stress resolution ability and adhesion are inferior. Particularly preferred.

In addition, the Cr-Zr-N layer 300 preferably has a thickness of 2 ~ 6㎛ to maintain high hardness and high lubrication characteristics.

At this time, the reason for limiting the thickness range is that when the thickness of 2㎛ or less has a high risk that the thin film characteristics are lower than its physical properties under the influence of the base material, when the thickness of 6㎛ or more increases the residual stress of the thin film Since the adhesion is inferior, the thickness range is appropriate.

Hereinafter, the manufacturing method of the coating | covering material (thin film) which concerns on this invention is demonstrated.

In order to manufacture the coating material of the present invention, the specimen (S) is first seated on the rotary jig 50, and then the rotary jig 50 is placed upwardly in place in the vacuum chamber 10.

At this time, in the vacuum chamber 10, the Cr and Zr deposition sources 30 and 40 which separate the target into two Cr and Zr, or the Cr-Zr deposition source 80 having the target as one Cr-Zr are the specimens (S). ) And a certain distance (5 ~ 15㎝) is arranged.

Subsequently, the inside of the vacuum chamber 10 is high-vacuumed by using the vacuum pump 20, and when the vacuum is completed, an appropriate amount of inert gas is supplied into the vacuum chamber 10 through the flow rate adjusting unit 70 to supply the atmosphere gas. Filled with.

Here, the supply flow rate of the inert gas is preferably 2.0 to 4.0 mTorr for Ar, and 0.8 to 2.0 mTorr for N ₂ .

This is to maintain a certain degree of vacuum in order to occur the plasma phenomenon, and in order to maintain the optimum plasma density, an amount of argon, which is an inert gas, must be injected. At this time, when nitrogen is injected, the amount of argon can be reduced.

However, if the amount of argon is too small, the deposition rate decreases because the amount of argon ions that collide with the target is small. If the amount of argon is too high, the particles falling off the target collide with argon and also lower the deposition rate. In the case of nitrogen, if the amount is too small, a high hardness compound will not be formed. If too much, excess nitrogen is adsorbed on the target surface, and the sputter yield of the target is drastically lowered by the poison effect. The above-mentioned amount is most suitable.

In this state, while supplying power while rotating the rotary jig 50 at a constant speed, each target is sputtered by ionized argon from the Cr target and the Zr target to form a Cr-Zr-N layer having high hardness and high lubrication characteristics. 300).

At this time, the rotational speed of the rotary jig 50 is preferably maintained at 10 ~ 20rpm, the source power supplied is preferably DC 10 ~ 20 W / ㎠ for Cr target, Pulsed DC 2.0 for Zr target 3.2A (Frequency: 20 kHz, Duty: 50%) is preferable.

Here, the reason for rotating the rotary jig 50 is that when using different types of targets, as shown in Figure 2 because the specimens are different from each target by distance and the deposition rate and composition is different for depositing a uniform thin film on the specimen will be.

In addition, the bias voltage applied to the specimen in the process is preferably a direct current -50 ~ -200V as described above.

Meanwhile, the present invention has been described for manufacturing the coating material of the present invention using an asymmetric magnetron sputtering method, but is not limited thereto, and other PVDs (such as cathode arc ion plating method, ion beam sputtering method, electron beam deposition method, resistance heating deposition method, etc.) Vapor deposition); Of course, it can also be produced by other CDV methods such as high temperature CVD (chemical vapor deposition), plasma CVD, MOCVD (metal organic substance deposition).

EXAMPLE

Hereinafter, an embodiment according to the present invention will be described.

First, the composition of the coating material of the present invention was configured as shown in Table 1 below, which is shown for the composition range of 42.9 ~ 75.8Cr-6.0 ~ 38.4Zr-18.2 ~ 20.7N in the weight percent of the technical idea of the present invention.

In this case, the atomic ratio (at%) described in Table 1 below refers to one of the concentration display methods, and is usually one of the display methods used to display the concentration in the ratio of atomic number for theoretical calculation.

As shown in Table 1, the process conditions of actually preparing the coating material of the present invention with the composition of components of the invention in which the composition ratio of Cr-Zr-N is changed are as follows.

◎ Process pressure: 4.2 × 10 ^-3 Torr

◎ Gas flow rate: Ar: 3.0mTorr / N ₂ : 1.2mTorr

◎ Magnetron Source:

Source 1: Pure Cr (99.9% or higher)

Source 2: Pure Zr (99.9% or higher purity)

◎ Source Power:

Source 1: DC 15.28 W / cm 2

Source 2: Pulsed DC 0.4-3.2A (Frequency: 20 kHz, Duty: 50%)

◎ Specimen temperature: about 200 ℃

◎ Rotating Jig Rotational Speed: 15 rpm

Specimen bias voltage: DC -100V

At this time, the discharging current of Cr target is to be constant (DC 15.28 W / ㎠) and the Zr target is changed by increasing the content of Zr sequentially while increasing the discharging current of Zr target (in 0.4A increments). Is the ratio according to the amount of Zr changed in this process.

In addition, the thin film prepared by using the existing material and the invention material 7 of the invention material and the surface texture and surface roughness by taking a scanning electron microscope and shown in Figure 5 and 6 shown in FIG.

As shown in Figure 5, the existing material thin film having a composition ratio when the Zr content = 0 exhibited columnar structure, and the surface 310 was very rough, the hardness was measured to be about 21GPa, the surface The roughness (310) was 5.2 nm.

In addition, as shown in Figure 6, the thin film made of the invention material 7 having a component composition ratio when Zr content = 34.3% by weight, that is, of 47.5wt% Cr-34.3wt% Zr-18.2wt% N layer (300 '). In this case, it appeared as a very fine thin film compared to the existing material, it was confirmed that the surface roughness has a very good roughness. In addition, the hardness at this time was measured to be about 34GPa, the surface 310 'roughness was 0.8nm.

Therefore, it was confirmed that the hardness and surface roughness improved as the x value increased.

Therefore, DLC, CrN, and the inventive materials 6, 7, and 8 according to the present invention were tested under the same abrasion test conditions, and the friction coefficient and lubricity test were compared to evaluate the characteristics of the present invention. And the results are shown graphically in FIG. 7.

◎ Specimen: 1.5 탆 thin film deposited on Si wafer 100

◎ Counterpart: AISI 52100 Steel Ball (Hv = 1100)

◎ load: 4N

◎ Speed: 220 rpm

◎ Temperature: Room temperature (25 ± 1 ℃)

◎ Experimental environment: in the air (comparative humidity: 50 and 90%)

As shown in the graph of Figure 7, in the case of the invention materials 6, 7, and 8 according to the present invention, the friction coefficient is lower in the humidity atmosphere of 50%, 90% than CrN, a conventional material known to have high hardness due to low wear rate. It was confirmed.

This means that the friction coefficient is as low as the friction coefficient under the above-mentioned humidity atmosphere, which means that even if the same load is applied to the thin film, less load is applied to the thin film of the low friction coefficient.

In addition, even when compared to DLC, which is known to have good lubricity, the coefficient of friction of Inventive Materials 6, 7, and 8 according to the present invention exhibits a coefficient of friction of 0.17 to 0.25, which is slightly higher than that of DLC having 0.1. However, in the high humidity atmosphere of 90%, DLC was found to be 0.23, while Inventive Materials 6, 7, and 8 according to the present invention were found to be 0.2 or less, which is remarkably superior to DLC.

Through these test results, the coating material of the present invention can be configured to have a high hardness value of 22 ~ 34Gpa, and also the friction coefficient can be lowered to 0.2 or less, 1.5 times higher hardness and friction coefficient than 60% than the existing CrN thin film In addition, it overcomes the limitations of existing hard coatings and solves the problems of temperature and humidity, which are disadvantages of DLC represented by lubricating thin film, and can be effectively applied to high temperature mold coating or wet high lubrication products. It is expected to be.

Therefore, by employing Zr in a certain ratio in a simple CrN thin film structure, it has high hardness characteristics, which is to be solved in the present invention, and is not easily worn even in a high temperature and humid atmosphere, and has excellent lubricity, thereby minimizing wear of the counterpart material. It has been found that new types of cladding can be produced.

As described in detail above, the present invention enables the manufacture of a high hardness thin film having extremely low abrasion rate by adding Zr to an existing CrN thin film, and also maintains its characteristics even in a high temperature or high humidity atmosphere, thereby making the surface treated product durable. It offers the advantage of significantly improving.

Claims (7)

In the coating material which vacuum-deposits on the base material of a metal mold | die or a lubrication product, and forms a thin film layer; The thin film layer is a high hardness, high lubricating coating material, characterized in that the composition consisting of 42.9 ~ 75.8Cr-6.0 ~ 38.4Zr-18.2 ~ 20.7N by weight. The method according to claim 1, The high hardness, high lubricity coating material, characterized in that the thickness of the thin film layer is 2 ~ 6㎛. The method according to claim 1, The thin film layer is a high hardness, high lubricating coating material, characterized in that it further comprises an intermediate layer made of Cr or CrN to relieve residual stress between the base material. Placing a base material for vacuum layer deposition on a rotating jig in the vacuum chamber, and mounting Cr and Zr deposition sources or Cr-Zr deposition sources with a magnetron source as a target; When the base material is disposed, vacuuming the inside of the vacuum chamber to 10 ⁻³ to 10 ⁻⁵ Torr and injecting an inert gas into the atmosphere gas; Generating an plasma by applying DC or pulsed DC to the source power while rotating the rotary jig at 10 to 20 rpm when the atmospheric gas is injected; A method of coating a high hardness, highly lubricating coating material, comprising the step of forming a thin film layer by vacuum depositing a plasma generated by applying a bias voltage to the base material to the base material. The method according to claim 4, In the magnetron source mounting step, the magnetron source is asymmetrically disposed inclined at an angle of 40 ~ 50 ° with the base material or installed adjacent to both sides perpendicular to the base material, characterized in that the coating method of high hardness, high lubrication coating . The method according to claim 4, In the thin film layer forming step, the method of coating a high hardness, high lubricating coating material, characterized in that it further comprises the step of forming an intermediate layer made of Cr or CrN between the base material and the thin film layer to relieve residual stress. The method according to claim 4, In the thin film layer forming step, the vacuum deposition method is performed by any one method selected from magnetron sputtering method, cathode arc ion plating method, ion beam sputtering method, electron beam deposition method, resistance heating deposition method, high temperature CVD method, plasma CVD method, MOCVD method Coating method of high hardness, high lubricating coating material, characterized in that.

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