KR101844687B1 - Manufacturing method for hard coatings with improved corrosion resistance - Google Patents

Abstract

An objective of the present invention to provide a novel configuration of a coating film and a manufacturing method thereof, capable of solving a problem in which defects are generated in a thin film according to an existing sputtering scheme when a high-hardness coating film is prepared. According to the above objective, the present invention provides a multilayered nanocomposite coating film prepared by forming a CrAlSiN layer on a base material to be subject to high-hardness coating by a hybrid coating scheme including arc ion plating, and forming an Al_2O_3 layer by atomic layer deposition (ALD). In other words, the present invention is directed to improve disadvantages of the high-hardness coating by performing a simplified ALD Al_2O_3 deposition process on the coating film by the hybrid coating scheme including the arc ion plating, which is an existing scheme of producing the high-hardness coating film. In a CrAlSiN/Al_2O_3 multilayered coating film produced by applying the hybrid coating scheme together with the ALD, CrAlSiN is formed by the hybrid coating scheme including the arc ion plating, and corrosion resistance and mechanical properties of CrAlSiN coating are enhanced by introduction of a nano-sized Al_2O_3 cover layer formed in a middle of the CrAlSiN/Al_2O_3 multilayered coating film by the ALD.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing a high hardness coating film having improved anti-

More particularly, the present invention relates to a method for producing a high hardness coating film having improved corrosion resistance, and more particularly, to a high hardness coating film using arc ion plating or arc ion plating and sputtering. And a simplified process which can be greatly improved.

High hardness coatings are widely applied in various industries. For example, when durability is required, such as cutting, forming, and casting tools, a high hardness coating is applied to improve hardness and improve chemical and thermal stability, thereby prolonging tool life and improving performance. In particular, a multi-component nitride-based high hardness coating film produced by mixing three or more elements such as CrAlN, CrSiN, CrAlSiN, TiAlN, TiSiN, and TiAlSiN has high hardness and excellent corrosion resistance and oxidation resistance, Has been widely studied and used as a protective film for improving the service life of tools and devices used.

 Generally, nitrided hard coating films are formed by arc ion plating in a nitrogen atmosphere in order to obtain high deposition rate and adhesion due to ionization. However, in the case of the multi-component hard coat film, In the case of elements such as Si, in which an insulating layer is formed in a nitrogen atmosphere, arc plasma is difficult to generate. In order to solve this problem, an element having conductivity even when nitrided such as Ti or Cr is deposited by arc ion plating, and at the same time, an element showing nonconductive when nitriding such as Al or Si is deposited using sputtering The hybrid coating method is utilized as a method for forming the multi-component coating films listed above.

However, in general PVD processes including arc ion plating and sputtering, hardened coatings by PVD processes often exhibit inherent defects because the species vaporized by the plasma have a linear-of-sight transfer characteristic , The defects appear as columnar grain structures, pinholes, holes, discontinuities, etc., and can adversely affect the corrosion resistance characteristics. Particularly, when the substrate or base material is a steel-based active alloy or is being used in a wear-corrosion process, corrosion due to such defects can easily occur.

Particularly, in order to secure the adhesion, in the case of using the arc ion plating alone or using the arc ion plating technique and the sputtering at the same time, the hybrid coating method produces a hard coating film, (Macroparticle) can easily be generated by ion agglomeration. The occurrence of such macro-particles acts as a defect of the coating film and forms a substantial part of the thickness of the coating layer, thereby causing a problem of greatly reducing corrosion resistance, which is an advantage of the multi-component hard coating film.

Accordingly, there is a need for an effective method for improving the corrosion resistance of a multicomponent hard coating film by utilizing current arc ion plating alone or hybrid coating method using arc ion plating and sputtering at the same time.

In CN Publication No. CN1321936C, the application of the Cr ₂ N-Al ₂ O ₃ nanocomposite to the hard coating is described, but it is difficult to propose a method of sintering after making the composition in terms of the manufacturing method, .

On the other hand, ALD (atomic layer deposition) methods have been established in various semiconductor and electronic industries. The ALD method has shown great potential for adaptability to corrosion protection surfaces for metal parts or devices that require high precision. In the ALD process, a precursor is introduced into the substrate surface, causing it to be introduced in alternating and distinctly applied pulses. Precursor pulses are isolated by inert gas purging and act on the substrate surface only. The material layer is grown through periodic repetition of the self-limiting surface reaction. The resulting thin film shows high quality, has few defects, has high uniformity, low process temperature, and is very easy to control film thickness. The advantage of this ALD is that it can block the pinholes and other defects that may remain in the coating structure, thus improving the corrosion protection function of the hard coat.

Recently, in Korean Patent No. 10-1659232, in order to manufacture a coating film having enhanced corrosion resistance characteristics of a hard coating film, CrN is coated with PVD in the base material and Al ₂ O ₃ is coated with ALD in the middle in a nano thickness, After finishing the defect in atomic layer units, the CrN is again coated with PVD. Such a hybrid coating film maintains high hardness and greatly improves corrosion resistance, but there is a problem that the process is troublesome because it requires PVD? ALD? PVD process.

Accordingly, an object of the present invention is to provide a novel coating film and a method of manufacturing the same, which can greatly improve corrosion resistance at the same time as the process efficiency in forming a multi-component hard coating film.

According to the above-mentioned object, the present invention provides a method of forming a CrAlSiN layer by a hybrid coating method between a HiPIMS method and an arc ion plating method, which is a PVD method, and a method of forming an Al ₂ O ₃ layer by ALD Thereby providing a coating film.

That is, the present inventors have attempted to improve the disadvantages of the hard coating film using only the conventional hybrid coating method and the manufacturing method by the deposition process of forming the ALD protective layer in the hybrid coating method, which is a conventional method of manufacturing a hard coating layer.

HiPIMS (high power impulse magnetron sputtering), due to the ability to generate a high technique potential to the sputtering method are receiving considerable attention throughout the industrial application, HiPIMS is 200μs with a high power density, such as from 1 to 3kW / cm ² The target can be sputtered with pulses having a short duration as much as possible to obtain a high ionization effect of the high density plasma and the sputtered species and the excellent coating density and the adhesion force of the coating film as compared with the conventional dc magnetron sputtering method .

In the CrAlSiN / Al ₂ O ₃ multilayer coating film fabricated by applying hybrid coating between HiPIMS and arc ion plating and ALD, CrAlSiN is formed by the hybrid coating method, and the Al ₂ O ₃ cover layer formed by ALD has a very thin thickness The Al ₂ O ₃ layer formed at this time covers the macroparticles and surface defects of the CrAlSiN hardness coating film and consequently improves the corrosion resistance of the thin film compared with the single CrAlSiN coating film.

The effect of the addition of the Al ₂ O ₃ interlayer, which is a microstructure coating layer, is surface roughness, mechanical properties, and corrosion properties, which have been investigated by the present inventors.

That is,

 1. A method of forming a coating film for improving physical properties of a base material of at least one of hardness, corrosion resistance, abrasion resistance and chemical stability,

The CrAlSiN layer is formed by a PVD (Physical Vapor Deposition) method including arc ion plating,

Formed CrAlSiN layer on the Al ₂ O ₃ layer of ALD (atomic layer deposition) to form by the that the functioning as a barrier layer at the interface, including the macro particles CrAlSiN layer was CrAlSiN / Al ₂ O ₃ which is characterized by a multi-layer coating film Lt; / RTI >

In the above, a multilayer coating film made of CrAlSiN / Al ₂ O ₃ has a thickness of Al ₂ O ₃ coating layer thinner than that of a CrAlSiN coating layer.

According to the present invention,

Al ₂ O ₃ layer is made of CrAlSiN / Al ₂ O ₃ in which the thickness of the Al ₂ O ₃ layer is controlled in the atomic layer unit and is inserted at 1 to 100 nm on the interface of macro particles of the CrAlSiN hardened film .

According to the present invention, by adding ALD to a nano-thick Al ₂ O ₃ layer on the CrAlSiN coating layer by the hybrid coating method, defects that can be formed in the CrAlSiN layer are compensated for. That is, the CrAlSiN / Al ₂ O ₃ multilayer coating film formed by efficiently blocking the Al ₂ O ₃ layer by the ALD from the columnar grain structure, pinhole, hole, and discontinuity that can be included in the CrAlSiN deposited by the hybrid coating method, Is changed into a structure that can not be easily realized. Particularly, the Al ₂ O ₃ layer effectively surrounds macro-particles inevitably generated by arc ion plating that constitutes the hybrid coating method.

Thus, the CrAlSiN / Al ₂ O ₃ multilayer coating film is commercially applicable to various tools and electrode bodies that have high hardness and high corrosion resistance, and which require corrosion resistance such as the marine environment.

In addition, since the PVD and ALD processes are performed once each, the present invention has an advantage in that the process is simpler than the conventional technique of inserting the ALD layer in the middle.

In addition, the CrAlSiN / Al ₂ O ₃ multilayer coating film of the present invention exhibited a very excellent corrosion resistance that can not be exhibited in conventional coating films with a corrosion resistance current I _corr of 1 × 10 ^-11 A / cm ² or less.

FIG. 1 shows a structural diagram of a coating film according to a process for improving the internal characteristics of the present invention and a trend of the corrosion current density according to the temporal progression.
FIG. 2 is a table showing process conditions for carrying out the hybrid coating method and the atomic layer deposition method of the present invention.
3 is a SEM photograph of the surface of the hard coating film before the ALD process according to the present invention is performed.
FIG. 4 shows the results of XRD analysis of specimens of CrAlSiN deposited on SUS base material and SUS base material by hybrid coating method, and CrAlSiN / Al ₂ O ₃ multilayer coating films of SUS base material coated with hybrid coating and ALD, respectively.
Figure 5 is a SUS base material, a hybrid coating method, a specimen, CrAlSiN / Al ₂ O ₃ multi-layer coating film of the above coins for specimens each coated with a hybrid coating method and ALD (Potentiodynamic Polarization Test) in the SUS base material coated with a CrAlSiN the SUS base material and Potentiostatic Polarization Test This is a graph of electrochemical characteristics measured by polarization experiment.
FIG. 6 shows a TEM photograph and composition of the hybrid coating method according to the present invention.

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

First, the production of a CrAlSiN / Al ₂ O ₃ multilayer coating film will be described.

An SUS304 substrate is prepared as a base material and ultrasonically cleaned, and then a Cr adhesive layer (also referred to as an adhesive layer) is formed to enhance the adhesion of the multilayer coating film to be formed thereafter. As the cleaning method, other methods such as plasma cleaning can be applied besides ultrasonic waves. The CrAlSiN layer is formed by a hybrid coating method between the arc ion plating and the HiPIMS method under the process conditions shown in FIG. CrAlSiN, a multicomponent coating film by a hybrid coating method including arc ion plating, includes a considerably large macro particle as shown in Fig. This may cause vulnerability to corrosion, and the presence of surface defects in CrAlSiN itself also presents the same problem.

In the TEM photograph shown in FIGS. 3 and 6, it is possible to confirm the presence of such macro particles and the corresponding defective portions.

The thickness of the CrAlSiN layer can be controlled by adjusting the deposition time.

Next, the Al ₂ O ₃ layer formed in the form of a defect-free uniform film on the CrAlSiN layer is formed by ALD and is formed by using TMA (trimethylaluminium) and H ₂ O precursor at 150 to 250 ° C, preferably 200 ° C And is deposited at a temperature of about < RTI ID = The ALD equipment used in this example was LUCIDA D100 ALD. During the deposition of the Al ₂ O ₃ layer, 50 sccm nitrogen gas was continuously supplied to the reactor. Inert gases other than nitrogen may be applied. For the uniform precursor supply, the canisters containing TMA and H ₂ O are maintained at a constant temperature of room temperature and slightly low temperature, respectively, and maintained at 25 ° C and 10 ° C, respectively, in this embodiment. The process conditions for the growth of the deposited film are shown in the right table of FIG. The thickness of the Al ₂ O ₃ layer can be controlled by adjusting the deposition cycle.

3 is a SEM photograph showing the surface morphology of CrAlSiN coating film before ALD-Al ₂ O ₃ formation. Micrographs of the surface and cross-section of the coating film were observed with a scanning electron microscope (SEM, Hitachi, S-4800, 15 KV). As shown in FIG. 1, it can be seen that a macro particle layer having various sizes and shapes is formed on the surface of the CrAlSiN layer. As shown in the enlarged image of the macro particle, a thin film is not formed around the macro particle Which are not observed. For this reason, macro-particles formed on the surface of the coating layer act as surface defects.

Also, in order to compare the characteristics of the CrAlSiN coating film with the CrAlSiN / Al ₂ O ₃ multilayer coating film, XRD was analyzed as shown in FIG. 4, and the electrochemical characteristics were measured as shown in FIG. The crystal structure of the coating film was observed using an X-ray diffractometer (XRD, D8-Discovery Brucker, 40 kV) emitting 1.54 Å Cu-Kα radiation.

The results of each test and observation will be described.

Figure 4 shows the XRD patterns of the respective coating and CrAlSiN CrAlSiN / Al ₂ O ₃ multi-layer coating. According to the standard reference values of the Joint Committee on Powder Diffraction (JCPDS, 76-2494), the main phases of CrAlSiN and CrAlSiN / Al ₂ O ₃ multilayer coatings all have a face-centered cubic structure, The peak can be identified by the planes of (111), (200), (220) and (222).

A weak Cr (110) peak was also observed, which is related to the Cr adhesive layer of the coating. No peak corresponding to the Al ₂ O ₃ phase having an amorphous structure was found. It can be confirmed that no peak indicating the formation of Cr ₂ O ₃ , CrO ₂ , Al ₂ O ₃ and SiO ₂ is formed after the ALD Al ₂ O ₃ layer is formed. This shows that ALD Al ₂ O ₃ formation Is carried out at a low temperature of 200 DEG C or lower

Next, the electrochemical characteristics of the CrAlSiN / Al ₂ O ₃ hard coat film are shown in FIG. For the electrochemical characterization, a 3.5 wt.% NaCl solution was used as the electrolyte. SCE was used as a reference electrode and Pt was used as a counter electrode. 5 (a) shows that the corrosion current of the CrAlSiN / Al ₂ O ₃ coating is 1 × 10 ^-11 A / cm ² or less, which is much higher than that of the CrAlSiN coating and SUS304 have. As shown in FIG. 5 (b), in the case of CrAlSiN / Al ₂ O ₃ coating, a constant current density was observed in the observation of the corrosion current over time through the electrostatic potential polarization experiment. On the other hand, in case of CrAlSiN coating film, corrosion due to pitting started to occur after about 8 ks.

FIG. 6 shows a TEM photograph as a result of actual observation corresponding to the schematic diagram shown in FIG. It showed that the particles contained in the macro CrAlSiN coating, the ALD-Al ₂ O ₃ covering layer can be verified that borrow methoxy closely the internal interface between the projecting surface and CrAlSiN CrAlSiN coating of the coated surface and the macro particles.

This can be explained by the following principle.

The defect-free, high-density Al ₂ O ₃ cover layer formed along the surface worked perfectly with an electron barrier in the coating film and an insulating barrier to block the flow of current from the anode to the cathode, Reducing the corrosion current density and reducing the rate of exchange of electrons at the corrosion interface and the dissolution rate of the anode metal ions. Particularly, when the arc ion plating method alone or a hybrid coating method using arc ion plating as in the embodiment is used, as shown in FIGS. 2 and 7, a large number of macro particles are present on the surface of the hard coat layer , Which is surrounded by a high-density Al ₂ O ₃ cover layer, thereby operating more efficiently.

In addition, the continuous Al ₂ O ₃ cover layer with low defect serves as a good barrier to prevent the diffusion of corrosive substances such as chlorine ions. Chlorine ions play an important role in the corrosion process because chlorine ions penetrate the protective layer formed on the surface of the coating to spontaneously increase corrosion resistance. Because of the small radius of chlorine ions, it can easily diffuse through columnar grain boundaries, internal intrinsic pinholes, coating defects, macroparticle protrusions, and reacts with metal ions such as soluble compounds . The Al ₂ O ₃ cover layer prevented the diffusion of chlorine ions and weakened their destructive effect and improved the corrosion resistance of CrAlSiN coatings.

As a result, it is considered that the Al ₂ O ₃ layer can exhibit the most important corrosion inhibition possible as a dense barrier layer around the macroparticles existing on the surface and the surface of the CrAlSiN layer. The thickness of the Al ₂ O ₃ layer may be selected within nano-size, especially 1 to 100 nm. This is in contrast to the fact that the thickness of the CrAlSiN layer before and after Al ₂ O ₃ formation is micro-sized (μm).

Conventionally, CrN is formed by PVD and CrN is formed by PVD on Al ₂ O ₃ layer formed on ALD on the CrN. In this case, the process design is substantially complicated. According to the present invention, PVD and ALD are performed once This completes the coating and makes it much simpler. Despite the simplified process, it exhibits better corrosion resistance than conventional coatings, which is very advantageous in industrial applicability.

It is to be understood that the invention is not limited to the disclosed embodiment, but is capable of many modifications and variations within the scope of the appended claims. It is self-evident.

No reference symbol.

Claims (3)

1. A method of forming a coating film for improving physical properties of a base material of at least one of hardness, corrosion resistance, abrasion resistance and chemical stability,
The CrAlSiN layer is formed by a hybrid coating method including arc ion plating alone or arc ion plating,
Of the formed Al ₂ O ₃ layer on CrAlSiN layer by ALD (atomic layer deposition) of the crystalline is CrAlSiN / Al ₂ O ₃ formed, characterized in that the function as a barrier layer at the interface, including the macro particles CrAlSiN layer presented by A method for forming a multilayer coating film. The method for forming a multilayer coating film according to claim 1, wherein the thickness of the Al ₂ O ₃ coating layer in the multi-layer coating film composed of CrAlSiN / Al ₂ O ₃ is thinner than that of the CrAlSiN coating layer. The Al ₂ O ₃ layer is coated on the CrAlSiN layer and the thickness of the Al ₂ O ₃ layer is controlled to be 1 to 100 nm by controlling the atomic layer unit so that the protruding surface of the macro particle contained in the CrAlSiN layer and the inner boundary surface with the CrAlSiN coating the multi-layer coating film by CrAlSiN / Al ₂ O ₃ characterized in that the Al ₂ O ₃ covering layer of a crystalline borrow methoxy.

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