WO2014109425A1 - Method for producing thin film on nanocrystalline max - Google Patents

Abstract

The present invention relates to making a thin film on Ti₂AlN MAX, and provides a method wherein, in contrast to the prior art in which an amorphous Ti₂AlN thin film that has been formed by sputtering or the like is given crystalline properties by being subjected to a subsequent heat treatment at a high temperature of about 800°C, a thin film is made directly into a crystalline thin film while being vapour-deposited at relatively low temperature. According to the present invention, outstanding crystalline thin films can be made at a relatively low temperature of between 400 and 500°C by making a Ti₂AlN target and by causing the ionisation of metal particles which are eroded and emerge from the target through the use of a plasma which is discharged upon applying an impulse voltage, and hence the range of choice of base materials is widened and the range of uses of thin films on Ti₂AlN MAX is widened.

Description

Manufacturing method of nanocrystalline MAA thin film

The present invention relates to a method for preparing a MAX phase thin film having a chemical formula of M _{n + 1} AX _n type, and more particularly, to a method for manufacturing a Ti ₂ AlN MAX phase thin film having nanocrystals.

MAX phase thin films are semi-ceramic And crystalline metal combined with a metal element A different from M, and have excellent physical properties such as electrical conductivity, oxidation resistance, and machinability. In particular, Ti₂The AlN MAX phase material has excellent oxidation resistance at high temperatures, and it is stable when the MAX phase material is used for articles that require fire resistance, such as aircraft turbine blades and internal combustion engine components such as automobiles, which need high temperature oxidation protection. It is very advantageous for operation and long life. In addition, it has low friction and wear resistance in addition to oxidation resistance to high temperature, it is recommended to be applied to a protective coating material, a low friction coating material, a sensor, an electrical contact point forming material.

According to the prior art, such a Ti ₂ AlN MAX phase material has been mixed with TiN and Al powder, sintered into a sintered body to make a block unit, and then drilled to produce the desired shape. Applicability of Ti ₂ AlN MAX phase material using this sintered body was very limited in that it must be sintered in block units and processed. Therefore, as an alternative for improving the applicability, been proposed to coat a thin film of Ti ₂ AlN MAX phase material on a base material requiring the properties of Ti ₂ AlN MAX phase material, it is coated with a method such as sputtering. However, the method for fabricating a thin film using the sputtering method requires post-annealing thereof because the state of the thin film formed by deposition is amorphous. That is, after the deposited thin film is subjected to a post-heat treatment at a high temperature of 600 to 800 ° C. in a vacuum to make amorphous, the coating process is completed with the Ti ₂ AlN MAX phase thin film.

This post-heat treatment process reduces productivity, and is not limited to the base material that can withstand the post-heat treatment process, and can be coated with a thin film of Ti ₂ AlN MAX. And the crack and / or peeling problem of the thin film due to the difference in thermal expansion coefficient of the coated thin film has a disadvantage.

Meanwhile, Korean Patent Publication No. 10-2004-0004091 discloses a method of manufacturing a Ti _{n + 1} AlN _n MAX phase thin film by a magnetron sputtering method, wherein a Ti / Al target and N ₂ gas are supplied to supply 700 to 900 ° C. Ti _{n + 1} AlN _n MAX phase thin film is manufactured at the process temperature. Although such a high temperature process can solve the productivity problem, it is still inapplicable since the base material itself requires high temperature durability, and the thermal expansion problem that can occur in the high temperature process and the Al fraction due to evaporation of Al provided as a target Deterioration may be a problem.

Accordingly, an object of the present invention is to provide a method of coating a Ti ₂ AlN thin film on the base material by lowering the temperature of the coating process so that the Ti ₂ AlN MAX phase thin film can be more variously applied. The purpose of the present invention is to provide a method for manufacturing a new MAX phase thin film to form a crystalline thin film and to be coated with a Ti ₂ AlN MAX phase thin film without a post heat treatment process.

The present invention,

In coating the base material with a thin film of Ti ₂ AlN MAX,

A target made of Ti ₂ AlN is installed in a vacuum, an inert gas is blown, and a plasma discharged by applying an impulse voltage is used to discharge metal elements from the target in an ion state directly to the base material. It is possible to provide a method for manufacturing a MAX phase thin film, which is characterized by coating with a crystalline Ti ₂ AlN MAX phase thin film.

In addition, the present invention, during the coating process, the base material may provide a method for producing a MAX phase thin film, characterized in that maintained at 300 to 500 ℃.

In addition, the present invention, in the above method, during the plasma operation to maintain a vacuum degree of 0.1 to 1Pa, the power of the plasma generator (plasma generator) to provide a thin film manufacturing method for the MAX phase, characterized in that to maintain 0.5 to 1kW. Can be.

In addition, the present invention can provide a method for manufacturing a MAX phase thin film, characterized in that the bias voltage of -10 to -90 V is applied to the target side.

In addition, in the above method, the target made of Ti ₂ AlN may provide a method for manufacturing a MAX phase thin film, characterized in that the Ti: Al: TiN is mixed by producing a sintered plasma.

In addition, the present invention, in the above method, the energy of the metal ion generated from the Ti ₂ AlN target can provide a method for producing a MAX phase thin film, characterized in that 50 to 100eV.

In addition, the present invention, in the above method, the base material may provide a MAX phase thin film manufacturing method, characterized in that the material having a durability at 300 to 500 ℃.

In addition, the present invention, in the above method, the target of Ti ₂ AlN can provide a MAX phase thin film manufacturing method, characterized in that the atomic ratio of Ti: Al: N is 2: 1.1 ~ 1.2: 1.8 ~ 2.0. .

According to the present invention, since the crystalline MAX phase thin film is directly formed in the thin film forming step without a separate post heat treatment process, productivity can be greatly improved.

In addition, the crystalline MAX phase thin film manufactured according to the present invention is formed by generating metal ions by a high-energy plasma, so that the crystalline thin film is formed at a lower temperature than the post-heating temperature, while the grain boundary has a low grain boundary. A thin film can be obtained and the oxidation resistance to hardness and high temperature can be improved.

In addition, since the crystalline MAX phase thin film is formed at a lower temperature than the post-heat treatment temperature, cracking or peeling of the thin film, which may occur due to different thermal expansion coefficients of the base material and the coated thin film, may be avoided.

In addition, the present invention can implement a crystalline MAX phase thin film coating at a considerably low temperature to increase the width of the base material can be applied, and due to the low process temperature, the ratio of Al loss from the Ti ₂ AlN target is rather small By controlling the atomic ratio of the Ti ₂ AlN MAX phase thin film of a superior composition can be coated.

In conclusion, according to the present invention, it is possible to simplify the production process and lower the process temperature to increase the applicability and to coat the thin film of superior physical properties compared to the conventional process.

Figure 1a is a table showing the composition of the MAX phase material.

Figure 1b is a crystal structure model to help understand the MAX phase material.

Figure 2 is a schematic diagram illustrating the generation of metal ions in the thin film forming process according to an embodiment of the present invention.

3 is a view for explaining preparation of a target used in the present invention.

Figure 4 is an XRD graph showing the characteristics of the target produced in the present invention.

Figure 5 is a graph showing the XRD results of the Ti ₂ AlN (110) MAX coated thin film prepared according to the embodiment of the present invention in comparison with the thin film according to the prior art.

6 is a graph showing the XRD results of the Ti ₂ AlN MAX phase coating thin film prepared for different substrates according to an embodiment of the present invention.

7 is a graph showing XRD results for differentially applying a bias voltage according to an embodiment of the present invention.

FIG. 8 is an SEM photograph of a Ti ₂ AlN MAX phase coated thin film prepared by varying deposition temperature in an embodiment of the present invention. FIG.

9 is a TEM photograph of a Ti ₂ AlN MAX phase coated thin film prepared in an embodiment of the present invention.

10 is a photograph of a SAED (Selected Area Electron Diffraction) pattern produced in an embodiment of the present invention.

11 is a table showing HIPIMS pulse parameters in an embodiment of the present invention.

FIG. 12 is a table illustrating EPMA (Electro Probe Micro Analyzer) results of a Ti ₂ AlN target and a Ti-Al-N coating film prepared therefrom in an embodiment of the present invention.

FIG. 13 is a TEM micrograph of a Ti ₂ AlN MAX phase coated thin film of nanocrystals prepared according to an embodiment of the present invention. FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1a is a table showing the composition elements for the MAX phase material, Figure 1b is a crystal structure model for the understanding of the MAX phase material, in the present embodiment, in particular, the Ti ₂ AlN MAX of the MAX phase materials listed in Figure 1a To produce a phase coating thin film. While the bond between the transition metal element X and the non-metal element X denoted by M is very strong, the bond between the non-transition metal denoted by A and MX is weak. As shown in FIG. 1B, the MX layers are stacked at nanometer intervals. In the meantime, element A is present with high activity. The MAX phase material is a semi-ceramic having evenly distributed properties of metal and ceramic, and has ductility, malleability, machinability, thermal and electrical conductivity, low friction, abrasion resistance, oxidation resistance, and corrosion resistance. Due to such excellent properties, it can be applied as a protective coating material, a low friction coating material, a sensor, an electrical contact point forming material and the like applied to a high temperature. In particular, in the case of Ti ₂ AlN, the high activity of Al atoms is to form an Al ₂ O ₃ protective layer on the surface of Ti ₂ AlN can withstand a long period of time even at high temperatures of around 800 ℃. Therefore, the protective coating thin film may be formed of Ti ₂ AlN or the electrode body on the aircraft turbine blade.

In order to directly manufacture the crystalline Ti ₂ AlN coating thin film, a base material and a target are prepared first.

In this embodiment, the base material was prepared by Si and Ti6242 alloy substrate, respectively, Ti6242 alloy means Ti ₆ Al ₂ Sn ₄ ZrMo. However, the base material is not limited to this, and other materials may be selected. In particular, the present invention may not be concerned about high temperature thermal deformation since the temperature of the manufacturing process is considerably low and does not perform high temperature post-heat treatment, and thus, a wide range of base material choices are made of stainless steel. Steel (SUS) may also be selected as a base material to raise the Ti ₂ AlN coating thin film.

As described above, in order to make the Ti ₂ AlN coated thin film crystalline from the thin film deposition step to eliminate the post-heat treatment process, the energy of the metal particles contributing to the thin film formation in the deposition process should be high, and above all, as shown in FIG. Protruding metal particles from the erosion must be ionized. To this end, in this embodiment, the target was made of Ti ₂ AlN and used. The target is prepared by mixing Ti: Al: TiN in an atomic ratio of 1: 1 to 2: 1, processing it by wet milling for about 2 hours, and plasma sintering at a high pressure of 40 MPa and a temperature of about 1230 ° C. for 10 minutes. It is possible to produce, and the target manufacturing apparatus is shown in FIG. In the present embodiment, Ti: Al: TiN was produced with an atomic ratio of 1: 1: 1, and this target has a density of 4.36, which has an excellent density without relatively internal pores, which is also a pressurized effect during fabrication. An XRD test result and a SEM photograph of the target and a graph showing the analyzed target composition are shown in FIG. 4. That is, it is composed of 50% Ti, 24% Al, 26% N, and it is a target composed of Ti ₂ AlN, and put it in a vacuum chamber to discharge the plasma using an inert gas such as Ar The target is eroded, thereby ionizing the protruding metal particles to coat the Ti ₂ AlN thin film on the base material.

As shown in FIG. 2, the thin film is formed directly into the crystalline thin film in the deposition step only when the degree of ionization of the metal particles is high. To this end, in the embodiment of the present invention by applying an impulse voltage and current to generate a high-energy plasma at a high density, preferably HIPIMS (used by Hauzer in the present embodiment) can be used.

After the base material and the target are mounted in the vacuum chamber, and the base pressure is set to 10 ^-3 Pa to 10 ^-2 Pa, argon gas is introduced to maintain the operating pressure at 0.1 to 1 Pa.

The power of the plasma generator was maintained at 0.5 to 1 kW, and the current was flowed at about 1 A / cm ² .

In particular, it is preferable to apply a bias voltage to the target so as to exert an attraction force that strongly attracts the generated plasma toward the target. In the present embodiment, a bias of -10 to -90 V, more preferably, -30 to -60 V I applied voltage.

In addition, in order for the Ti ₂ AlN thin film to be formed to be crystalline from the deposition step, the energy of the ion to be deposited and the temperature combined therewith are important factors, and the base metal is maintained at 400 to 500 ° C. during the deposition process. It is desirable that the crystalline MAX phase thin film be formed at a much lower temperature than the prior art as metal ions provide a significant portion of the energy required for crystalline formation.

The deposition process using the plasma may vary depending on the thickness of the desired coating thin film, and if the coating layer is equipped with high temperature oxidation resistance, such as an aircraft turbine blade, the coating film may be formed up to μm, but low friction, such as forming a sensor or an electrical contact point If the use requires a thin film of the nm level may be formed.

Figure 5 is a graph showing the XRD results of the Ti ₂ AlN MAX phase coated thin film prepared by using the base material according to the embodiment of the present invention in comparison with that for the thin film according to the prior art, the graph represented by (a) is a conventional The Ti ₂ AlN thin film was manufactured using a DC pulse, indicating that TiN and Ti ₂ AlN of AlTi, fcc were mixed. On the other hand, the Ti ₂ AlN thin film according to the present embodiment is different depending on the temperature variables of room temperature, 300 ℃, 450 ℃, but produced at 450 ℃ temperature that the Ti ₂ AlN thin film having a crystal plane (110) was formed. It can be confirmed, and thus it can be seen that a crystalline Ti ₂ AlN thin film can be obtained immediately at the thin film manufacturing step. If the temperature is room temperature or less than about 300 ℃, it is present in the state of AlTi, AlTi ₃ and the like, it can be seen that to obtain the desired crystalline thin film to maintain the temperature at an appropriate level even when the degree of metal ionization is high. In the above, the direction of the crystal surface can be formed differently depending on the conditions, and is not limited.

In FIG. 6, the XRD graph for the case of using the Si and Ti6242 alloys as the base substrate, respectively, also shows the base material component in the thin film, which means that the thin film is formed very thinly on the substrate, and it can be predicted that the adhesion between the thin film and the base material is strong. have. This means that the crystalline film is formed at a relatively low temperature, and thus a thin film of good quality can be formed without crack separation due to a difference in thermal expansion coefficient.

7 includes experimental data in which the bias voltage is optimized, and it can be seen that about -30 to -90 V, and preferably, about -50 V is the optimum bias.

8 is a SEM photograph of a Ti ₂ AlN thin film formed at room temperature and at 450 ° C. with a base substrate as Si, respectively, and the thin film formed at 450 ° C. shows a morphology capable of knowing the growth direction, and is crystalline at 450 ° C. rather than at room temperature. It can be seen that the thin film is advantageous for growth.

FIG. 9 is a TEM image of a Ti ₂ AlN thin film having a base substrate as Si, whereby the crystal growth direction of the thin film can be seen more clearly than in FIG. 8.

FIG. 10 shows more clearly that the thin film was grown crystalline in the SAED pattern of the Ti ₂ AlN thin film with the base substrate as Si.

In particular, Figure 13 shows a TEM micrograph of a specimen deposited with a bias voltage of -60V on a Si (100) substrate, (a) a bright image, (b) a dark image, (c) a selected area diffraction pattern, (d) and (e) is HRTEM (high resolution TEM), it can be confirmed that the nano-sized crystals are formed.

In this way, the Ti ₂ AlN MAX thin film can be directly produced in a crystalline state in the deposition step without a post-heat treatment process.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self-evident.

According to the present invention, since the Ti ₂ AlN MAX phase thin film is formed at a relatively low temperature of 500 ° C. or less, it can be used as a base material as long as it does not deform within the above temperature range.

Therefore, the base material can be diversified compared to the conventional Si, Ti6242 alloy substrate, stainless steel and the like.

The Ti ₂ AlN MAX phase thin film is formed by using a high power impulse magnetron sputtering (HIPIMS) Ti ₂ AlN target.

The Ti ₂ AlN target may be fabricated by plasma sintering. As a result of analysis by EPMA on the target thus manufactured, Ti: Al: N: O = 0.47: 0.22: 0.25: 0.06 as shown in FIG. The composition of the Ti ₂ AlN MAX thin film manufactured with the target was also shown in FIG. 12. This suggests that the number of collisions of Al, which is 1.3 times longer than Ti, is smaller than that of Ti, and that Al is evaporated, causing Al to be deficient. In the case of N, the diffusion rate is similar, so similar deficiency may occur. As a result, a nanocomposite in which a small amount of Ti ₂ N coexists in the thin film of Ti ₂ AlN MAX may be formed. Since the formation of Ti ₂ N is caused by Al deficiency, the composition ratio can be controlled in the production of Ti ₂ AlN target to improve this. That is, the atomic ratio of Ti: Al: N can be set to 2: 1.1 to 1.2: 1.8 to 2.0, preferably 2: 1.12: 1.9.

The plasma is discharged using an inert gas, such as Ar, into a vacuum chamber, and the target is eroded. Thus, the protruding metal particles are ionized to coat the Ti ₂ AlN thin film on the base material.

In the embodiment of the present invention by applying an impulse voltage and current to generate a high-energy plasma at high density, it can use a HIPIMS (Hauzer company) device. The parameters are shown in FIG. 11 as a preferred embodiment of HIPIMS.

The base pressure is 4 × 10 ^-3 Pa, inert gas such as argon is blown near the target to maintain the operating pressure at 0.5 Pa, and the temperature was changed from room temperature to 300 to 450 ℃ to perform the thin film coating. Was 0 to -70V. The distance between the target and the substrate was maintained at about 8 cm, and the deposition rate was 0.9 to 1.2 μm / h. Therefore, the film thickness is controlled by the deposition time.

In this way, the Ti ₂ AlN MAX phase thin film can be manufactured at a relatively low temperature.

The rights of the present invention are not limited to the embodiments described above, but are defined by the claims, and those skilled in the art can make various modifications and adaptations within the scope of the claims. It is self-evident.

The coating of the Ti ₂ AlN MAX phase thin film of the present invention is applied to various articles requiring fire resistance, low friction, and abrasion resistance, such as aircraft or automobile parts, internal combustion engine parts, protective coating materials, low friction coating materials, sensors, and electrical contact point forming materials. Can be applied.

Claims (8)

1. In coating the base material with a thin film of Ti ₂ AlN MAX,

   A target made of Ti ₂ AlN is installed in a vacuum, an inert gas is blown, and a plasma discharged by applying an impulse voltage is used to discharge metal elements from the target in an ion state directly to the base material. MAX phase thin film manufacturing method, characterized in that the coating treatment with a crystalline Ti ₂ AlN MAX phase thin film.
2. The method of claim 1, wherein the base material is maintained at 300 to 500 ° C. during the coating process.
3. The method of claim 1 or 2, wherein the vacuum during plasma operation is maintained at 0.1 to 1 Pa, and the power of the plasma generator is maintained at 0.5 to 1 kW.
4. 4. The method of claim 3, wherein a bias voltage of -10 to -90 V is applied to the target side.
5. The method of claim 1, wherein the target made of Ti ₂ AlN is manufactured by sintering with plasma by mixing Ti: Al: TiN.
6. The method of claim 1, wherein the energy of the metal ions generated from the Ti ₂ AlN target is 50 to 100 eV.
7. The method of claim 1, wherein the base material is a material having durability at 300 to 500 ° C. 4.
8. The method of claim 5, wherein the target of Ti ₂ AlN has an atomic ratio of Ti: Al: N of 2: 1.1 to 1.2: 1.8 to 2.0.

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