JP7247452B2 - coated tool - Google Patents

Description

The present invention provides, for example, a tool used for a cutting tool such as a mold for press working or casting, an insert, etc., which is a hard tool containing a nitride or carbonitride containing Al and Cr coated by a chemical vapor deposition method. It relates to a coated tool having a coating on the surface of the tool.

2. Description of the Related Art Conventionally, in order to extend the life of tools such as molds and cutting tools, coated tools are used in which the surfaces of the tools are coated with a hard film by a physical vapor deposition method or a chemical vapor deposition method. Among various hard coatings, hard coatings composed of nitrides or carbonitrides of Al and Ti and hard coatings composed of nitrides or carbonitrides of Al and Cr are excellent in wear resistance and heat resistance. Widely used for coated cutting tools.
Physical vapor deposition and chemical vapor deposition are widely applied to coated cutting tools that are actually on the market to form hard coatings made of nitrides or carbonitrides of Al and Ti. On the other hand, regarding the formation of hard coatings made of nitrides or carbonitrides of Al and Cr, physical vapor deposition is applied to coated cutting tools that are actually on the market, and chemical vapor deposition is applied. The current situation is that it is not.

However, _research has been conducted _on the _{formation of hard coatings} by chemical vapor deposition. _3. Coating the surface of the tool substrate with a hard coating made of nitrides of Al and Cr having a cubic crystal structure by separately supplying gas group B consisting of N ₂ and H ₂ as hard coating raw material gases. disclosed.

JP 2017-80883 A

Regarding the coating described in Patent Document 1, according to the study of the present inventor, when a hard coating made of nitrides of Al and Cr is coated by chemical vapor deposition, _NH3 gas, which is an alkaline gas, and CrCl, which is a halogen gas, are used. It was confirmed that the ₃ gas and AlCl ₃ gas react excessively, making it difficult to form a stable film, and that the durability when used as a coated tool including a coated cutting tool is sometimes insufficient.
Accordingly, an object of the present invention is to obtain a coated tool coated with a nitride or carbonitride of Al and Cr having excellent durability.

A tool according to one embodiment of the present invention comprises:
The hard coating is a chemical vapor deposition film , and the average content ratio of Al is 50 atomic % or more, Cr is 10 atomic % or more, and the total content ratio of Al and Cr is 90 atoms with respect to the total amount of metal elements including semimetals. % or more of nitrides or carbonitrides,
Composed of an aggregate of columnar particles grown in the film thickness direction on the surface of the base material,
On the (111) plane, (200) plane, (220) plane, (311) plane, (222) plane, (400) plane, (331) plane, (420) plane and (422) plane resulting from the fcc structure TA, (311) plane , (222) plane, (400) plane, (331) plane, (420) plane and (422) plane. When the total peak intensity is TB, the value of TB / TA is 0.40 or more and 0.70 or less ,
the law of nature,
An intermediate coating containing Ti nitride or carbonitride is provided between the base material and the hard coating.

Furthermore, in the tool according to the embodiment, the hard coating has a single-layer structure portion with a relatively high Al content and a portion with a relatively high Al content in the microstructure using a transmission electron microscope. It is preferable that the crystal grains having a portion of low lamination structure are dispersed.

According to the above, it is possible to obtain a coated tool coated with nitrides or carbonitrides of Al and Cr with excellent durability.

1 is a diagram showing the results of X-ray diffraction measurement of Example 1. FIG. FIG. 10 is a diagram showing the results of X-ray diffraction measurement of Example 2; FIG. 10 is a diagram showing the results of X-ray diffraction measurement of Example 3; 3 is a diagram showing the results of X-ray diffraction measurement of Comparative Example 1. FIG. FIG. 10 is a diagram showing X-ray diffraction measurement results of Comparative Example 2; 1 is a schematic diagram of a chemical vapor deposition apparatus (CVD furnace) used for coating hard coatings in Examples. FIG. FIG. 2 is an enlarged schematic schematic diagram of a main part of a chemical vapor deposition apparatus (CVD furnace) used for coating a hard coating in Examples. FIG. 2 is a schematic cross-sectional view of a gas jetting port of a chemical vapor deposition apparatus (CVD furnace) used for coating hard coatings in Examples. 2 is an enlarged TEM photograph (magnification: 2,000,000 times) of the hard coating of Example 1. FIG. FIG. 10 is a schematic diagram of FIG. 9;

The present inventors have found that by increasing the X-ray diffraction peak intensity due to the crystal plane on the high angle side for nitrides or carbonitrides mainly composed of Al and Cr, coated cutting tools with a large processing load among tools. We have found that durability is improved when used as a coating film, and have arrived at the present invention based on the idea that this finding can be applied to the aforementioned coated tools in general. That is, for nitrides or carbonitrides mainly composed of Al and Cr, X Focusing on the relative intensity of the sum of the X-ray diffraction peak intensities, we found that when the relative intensity of the sum of these X-ray diffraction peak intensities is above a certain level, the durability of the coated tool is improved. It was.
In addition, in order to improve the durability and stabilize the film formation, it is necessary not to allow the NH ₃ gas, which is an alkali gas, and the CrCl ₃ gas or AlCl ₃ gas, which are halogen gases, to react excessively. It is also found that the ratio of the amount of NH ₃ gas in the mixed gas of is specified to the total amount of N ₂ gas and H ₂ gas, and that the Cr chloride gas needs to be generated in the CVD furnace. bottom.
Hereinafter, the composition, structure, crystal structure, characteristics, and details of the manufacturing apparatus of the hard coating forming the coated tool of one embodiment of the present invention will be described.
In this specification, when a numerical range is expressed using "-", the range includes upper and lower limits.

<Composition>
First, the composition of the hard coating according to this embodiment will be described.
The hard coating according to this embodiment is a nitride or carbonitride based on Al and Cr. A nitride or carbonitride film of Al and Cr is a film excellent in wear resistance and heat resistance. Even in the case of carbonitride, if the total content ratio (atomic %) of nitrogen and carbon is 100% in the average composition of the hard coating, the nitrogen content ratio (atomic %) is 80% or more. Preferably. If the hard coating consists mainly of nitrides, which are excellent in heat resistance, the durability of the coated tool will not be significantly reduced even if carbonitrides and the like are partially contained. More preferably, when the total content ratio (atomic %) of nitrogen and carbon is 100%, the content ratio (atomic %) of nitrogen is 90% or more. In addition, the carbon contained in the hard coating may be contained as free carbon.

<<Aluminum Al>>
When the average content of Al is high, the heat resistance of the hard coating increases, and it becomes easier to form a lubricating protective coating on the tool surface, improving the durability of the coated tool. In order to fully reproduce these effects, the hard coating according to the present embodiment has an Al content ratio of 50 atomic % with respect to the total amount of metal elements including semimetals (hereinafter referred to as metal elements). That's it. Furthermore, it is preferable to set the content ratio of Al to 55 atomic % or more. Furthermore, it is more preferable to set the content ratio of Al to 60 atomic % or more. Furthermore, it is even more preferable to set the content ratio of Al to 70 atomic % or more. However, if the content of Al is too high, AlN with a fragile hcp structure increases and the durability of the coated tool decreases. Therefore, it is preferable to set the Al content ratio to 90 atomic % or less.

<<Chromium Cr>>
If the average Cr content ratio is too low, AlN with a brittle hcp structure increases too much, and the durability of the coated tool decreases. In addition, it becomes difficult to form a lubricating protective film on the surface of the tool (the surface of the cutting edge in the case of a cutting tool), and adhesion is likely to occur. Also, for this reason, the content ratio of Cr is set to 10 atomic % or more. Furthermore, it is preferable that the content ratio of Cr is 15 atomic % or more. However, if the content ratio of Cr becomes too high, the content ratio of Al relatively decreases, resulting in a decrease in heat resistance. Therefore, the content ratio of Cr is preferably 45 atomic % or less.

<<other elements>>
The hard coating according to the present embodiment preferably has a total content ratio of Al and Cr of 90 atomic % or more in order to impart higher heat resistance to the hard coating. Furthermore, it is preferable to set the total content ratio of Al and Cr to 95 atomic % or more. The hard coating according to this embodiment may contain metal elements other than Al and Cr, such as Ti, Si, Zr, B, and V. These elements are elements generally added to AlTi-based nitrides or carbonitrides and AlCr-based nitrides or carbonitrides, and if added in small amounts, the durability of the coated tool is significantly reduced. It contributes to the improvement of durability depending on the use of the tool. That is, in the nitride having a total content of Al and Cr of 90 atomic % or more, the (311) plane, (222) plane, (400) plane, (331) plane, (420) plane and (422) plane described later ) if the relative strength of the total peak strength due to the surface is a certain value or more, even if these metal elements are contained, the durability of the coated tool will not be significantly reduced, and depending on the use of the tool, the durability Contribute to improvement. However, if the content ratio of metal elements other than Al and Cr becomes too high, the basic properties of nitrides or carbonitrides based on Al and Cr are degraded, and the durability of the coated tool is degraded. Therefore, when other metal elements are contained, the content ratio is preferably 10 atomic % or less.

<<Inevitable Impurities>>
The hard coating according to the present embodiment can contain, as unavoidable impurities, up to 1% by mass or less of components contained in the film forming gas such as oxygen and chlorine when the entire hard coating is taken as 100% by mass. If the hard coating according to the present embodiment is a nitride or carbonitride as a whole, it may partially contain compounds derived from these impurities.

<Crystal structure>
The hard coating according to the present embodiment has the (111) plane, (200) plane, (220) plane, (311) plane, (222) plane, (400) plane, ( It has peak intensities on the 331), (420) and (422) planes.
As long as it has the peak intensity due to these fcc structures, it may partially have the peak intensity due to the hcp structure. However, if the peak strength due to the hcp structure becomes too large, the durability of the coated tool will decrease.
Therefore, even when the hcp structure is contained, the maximum peak intensity of the peak due to the hcp structure is preferably 1/10 or less of the maximum peak intensity of the peak due to the fcc structure.

In the X-ray diffraction, the hard coating according to the present embodiment has the fcc structure (111) plane, (200) plane, (220) plane, (311) plane, (222) plane, (400) plane, (331) plane It has peak intensities in at least nine planes, the (420) plane and the (422) plane. Having peak strength in the (422) plane on the higher angle side improves the durability of the coated tool. Usually, nitrides mainly composed of Al and Cr coated by arc ion plating tend to have relatively high peak intensities of (111) plane, (200) plane, and (220) plane on the low angle side. be. In nitrides or carbonitrides mainly composed of Al and Cr coated by chemical vapor deposition with devised film formation conditions, the present inventors found that the (311) plane, (222) plane, and (400) plane on the high angle side It has been found that the durability of the coated tool is improved by increasing the relative intensity of the sum of the peak intensities attributed to the plane, (331) plane, (420) plane and (422) plane.
(111) plane, (200) plane, (220) plane, (311) plane, (222) plane, (400) plane, (331) plane, (420) plane and the sum of peak intensities due to (422) plane TA, (311) plane, (222) plane, (400) plane, (331) plane, ( When TB is the sum of the peak intensities attributed to the 420) plane and the (422) plane, a TB/TA value of 0.40 or more can improve the durability of the coated tool. Preferably, the value of TB/TA is 0.50 or more. More preferably, the value of TB/TA is 0.55 or more. Even if the peak intensity of the (111) plane, (200) plane, and (220) plane on the low angle side is too low, the basic properties of the hard coating deteriorate, so the value of TB/TA should be 0.70 or less. preferable.

Since there are no diffraction peaks for aluminum chromium nitride and aluminum chromium carbonitride in the ICDD file, the diffraction peak intensity of each crystal plane is obtained from fcc structure aluminum nitride described in ICDD file number 00-025-1495. Although ICDD file number 00-025-1495 has no peak intensity of the (422) plane, the peak intensity of the (422) plane can be confirmed in the X-ray diffraction diagram by calculating the interplanar spacing d value.
The X-ray diffraction peaks of the aluminum chromium nitride hard coating and the aluminum chromium carbonitride hard coating are similar to the X-ray diffraction peaks of the titanium aluminum nitride hard coating, and the peak positions overlap. Therefore, when the hard coating according to the present invention and the titanium aluminum nitride hard coating are laminated, for example, alternately laminated, the obtained X-ray diffraction peak is TB/TA as the peak of the aluminum chromium nitride hard coating and the aluminum chromium carbonitride hard coating. The value of is calculated.

<Column particles>
The hard coating according to this embodiment is composed of an aggregate of columnar particles grown in the film thickness direction on the surface of the base material. The hard coating of nitride or carbonitride based on Al and Cr forms columnar particles grown in the film thickness direction on the surface of the base material, thereby improving the durability of the coated tool.
The average width of the columnar particles on the surface side is preferably 0.1 μm or more and 2.0 μm or less. When the average width on the surface side is 0.1 μm or more, the durability of the coated tool is further enhanced. Further, by setting the average width on the surface side to 2.0 μm or less, plastic deformation of the hard coating is less likely to occur, and the diameter of the particles falling off from the hard coating is reduced, making it easier to suppress tool wear.

In this embodiment, the surface side refers to the vicinity of the surface of the hard coating on the side in contact with the workpiece, for example, the vicinity of the CP (Cross-section Polisher) processing surface. The width of the columnar grains of the hard coating can be measured by cross-sectional observation with a transmission electron microscope or scanning electron microscope. The measurement point was set at a depth of 0.5 μm from the coating surface on the side in contact with the workpiece. Observing the width of 30 or more continuous columnar particles converges the average value of the particle width. Therefore, the average width of the columnar grains of the hard coating can be obtained from 30 or more continuous columnar grains.

<Microstructure>
Although the microstructure of the hard coating according to the present embodiment is not particularly limited, it is preferable that crystal grains in which a single layer structure and a laminated structure coexist are dispersed in one particle. Specifically, for example, in one crystal grain, a nitride or carbonitride of Al and Cr having a relatively high Al content and a nitride or carbonitride of Al and Cr having a relatively low Al content Crystal grains having a portion having a laminated structure in which carbonitrides are alternately laminated and a portion having a single-layer structure of a nitride or carbonitride of Al and Cr having a high Al content are dispersed in the microstructure. There is a case (see FIGS. 9 and 10 relating to Embodiment 1 described later).
It is presumed that the portion with the single layer structure has less strain than the portion with the laminated structure. Therefore, the durability of the coated tool is improved by having the part with the single layer structure. Since the Al content ratio of the portion having the laminated structure is relatively smaller than that of the portion having the single layer structure, the Al content of the crystal grain as a whole increases excessively, resulting in AlN having a fragile hcp structure. increase is suppressed. The presence of such particles makes it possible for the hard coating as a whole to exhibit improved wear resistance and heat resistance and excellent durability.
The microstructure of the hard coating according to this embodiment may have crystal grains consisting only of a single layer structure. Further, it may have crystal grains having only a laminated structure. It may have crystal grains having only a single layer structure, crystal grains having only a laminated structure, and crystal grains having both a single layer structure and a laminated structure.

In the portion of the laminated structure, the Al and Cr nitrides or carbonitrides having a relatively high Al content ratio preferably have an Al content ratio of 60 atomic % or more, and a relatively Al content The nitride or carbonitride of Al and Cr having a low ratio preferably has an Al content ratio of 55 atomic % or less.
In the laminated structure portion, the Al and Cr nitrides or carbonitrides having a relatively high Al content ratio preferably have an Al content ratio of 70 atomic % or more, and more preferably 80 atomic % or more. It is more preferable to have However, if the Al content ratio is too high, the amount of AlN having the hcp structure increases, so the Al content ratio is preferably 95 atomic % or less. Furthermore, it is preferably 90 atomic % or less.
In the laminated structure portion, the Al and Cr nitrides or carbonitrides having a relatively low Al content ratio preferably have an Al content ratio of 50 atomic % or less, further preferably 40 atomic % or less. is even more preferable. However, if the content of Al is too low, the heat resistance of the entire hard coating is lowered, so the content of Al is preferably 10 atomic % or more. Furthermore, 20 atomic % or more is preferable.
It is preferable that the single-layer structure portion has an Al content of 60 atomic % or more. Furthermore, it is more preferable that the content ratio of Al is 70 atomic % or more. However, if the content ratio of Al becomes too high, AlN having the hcp structure increases, so the content ratio is preferably 90 atomic % or less.

<Average layer thickness>
The average layer thickness (film thickness) of the hard coating according to this embodiment is desirably 1.0 to 15.0 μm. The reason for this is that if the thickness is less than 1.0 μm, it is too thin to provide a sufficient tool life, while if it exceeds 15.0 μm, it is too thick and there is a possibility that the machining accuracy will be lowered. The lower limit of the film thickness is preferably 2.0 μm, more preferably 3.0 μm, and more preferably 5.0 μm. The upper limit of the film thickness is preferably 12.0 µm, more preferably 10.0 µm.

<Intermediate film and upper layer>
In the coated tool of the present embodiment, an intermediate coating containing Ti nitride or carbonitride is provided between the base material of the tool and the hard coating in order to further improve the adhesion of the hard coating to the base material. By providing such an intermediate film, the adhesion between the base material and the hard film is further improved, and the durability is improved even under severe use environments. Here, in this specification, when a compound is not represented by a chemical formula such as Ti nitride or carbonitride, it is not necessarily limited to a stoichiometric range, and Ti nitride or carbonitride To include means to allow the presence of a layer that is unavoidably formed when forming a film of Ti nitride or Ti carbonitride as an intermediate layer.
Further, an upper layer having a different component ratio or composition from the hard coating according to the present embodiment may be provided on the hard coating according to the present embodiment. The upper layer is, for example, a nitride, a carbonitride, a carbide, or an oxide such as alumina, and is preferably provided via a bonding layer. Among these, alumina, which is generally used as a coating layer formed by chemical vapor deposition, is preferable because it improves the heat resistance of coated tools. For example, a coated cutting tool provided with alumina is generally used in the cutting of castings. The coated tool of the present invention is also preferably provided with alumina as an upper layer, as required, to further improve durability.
When applied to a mold, a nitride or carbonitride of V having excellent lubricity may be provided as an upper layer.

<Treatment after coating>
Since the hard coating according to the present embodiment is formed by chemical vapor deposition and has tensile stress, it is preferable to perform a post-coating treatment for stress release by a blasting device or the like after coating. By performing this post-coating treatment, a hard coating with improved chipping resistance in cutting and excellent tool life can be obtained.

<Base material>
In this embodiment, the base material (the base material of the coated tool) is not particularly limited, and can be appropriately selected according to the application, purpose, and the like. For example, cemented carbide, cold work tool steel, high speed tool steel, plastic mold steel, hot work tool steel, etc. can be applied.
When the coated tool of the present invention is used as a cutting tool, the tool base material is not limited to the insert base material. , taps and the like.

<Manufacturing method>
The hard coating according to the present embodiment can be produced, for example, by introducing a mixed gas A and a mixed gas B described below separately into a chemical vapor deposition apparatus (CVD furnace) whose internal temperature has been raised to 750° C. or higher, which will be described later. Mixing in the apparatus can coat a tool substrate, such as an insert substrate, that has been previously placed in the apparatus.

<<mixed gas A>>
In this embodiment, mixed gas A includes mixed gas a1 and mixed gas a2. The mixed gas a1 is HCl gas and _H2 gas (also referred to as "mixed gas for producing Cr chloride" or "mixed gas for obtaining mixed gas a1"), and these two gases are brought into contact with metal Cr. A gas containing Cr chloride gas (a gas in which Cr and Cl are chemically combined as well as a component that can _be expressed as _CrCl3 ) generated by = 0.008 to 0.140. On the other hand, the mixed gas a2 is a gas containing AlCl ₃ gas and H ₂ gas, and has a typical composition of AlCl ₃ /(H ₂ +N ₂ )=0.0006 to 0.0300 by volume.
The volume % of Cr chloride gas and the volume % of AlCl ₃ gas are estimated from the amount of HCl gas introduced to generate these gases, as will be described later.
In the mixed gas a1, HCl gas and _H2 gas for generating Cr chloride gas are heated and brought into contact with metal Cr. It is preferable to carry out in the gas preheating section. Further, it is preferable to obtain a mixed gas A by mixing a mixed gas a1 containing Cr chloride gas with a mixed gas a2 heated to a temperature close to that of the mixed gas a1. By doing so, the Cr chloride gas can be easily generated without being affected by the AlCl ₃ gas.
In the mixed gas a1, HCl gas and _H2 gas for generating Cr chloride gas are heated and brought into contact with metal Cr. It is preferable to carry out in the gas preheating section. The temperature at which Cr chloride gas is generated in the gas preheating section is set to a temperature at which Cr chloride gas is stably generated at about 750° C., which is the minimum set temperature of the furnace temperature. The reason for this is that if this temperature is too low, the amount of Cr chloride gas generated is reduced, the entire hard coating becomes Al-rich, and AlN with the hcp structure tends to increase.
Further, the AlCl ₃ gas contained in the mixed gas a2 can be generated, for example, by introducing a mixed gas of H ₂ gas and HCl gas into an AlCl ₃ gas generator filled with metal Al and kept at 330 ° C. It can be preheated when it is mixed with mixed gas a1 to form mixed gas A. It is preferable that the temperature of the mixed gas a2 is not much different from the temperature of the mixed gas a1, so that the hard coating becomes columnar particles.
In mixed gas A obtained by mixing mixed gas a1 with mixed gas a2, it is desirable to maximize the flow rate of H ₂ gas. Furthermore, the mixed gas a1 and the mixed gas a2 may contain N ₂ gas and Ar gas.

<<mixed gas B>>
Mixed gas B includes _H2 gas, _N2 gas and _NH3 gas. This mixed gas B has a composition ratio in which the value of b2/b1 is 0.002 or more and 0.020 or less, where b1 is the total volume percentage of N ₂ gas and H ₂ gas and b2 is the volume percentage of NH ₃ gas. is preferable for obtaining the composition of the hard coating according to the present embodiment. If the composition ratio of the mixed gas B is within this composition ratio range, it becomes easier to suppress excessive reaction between the NH ₃ gas, which is an alkali gas, and the CrCl ₃ gas or AlCl ₃ gas, which is a halogen gas.
This mixed gas B is also preheated, but the temperature rise due to preheating is suppressed and preheated to a temperature lower than that of the mixed gas A to avoid excessive preheating.
In the coating apparatus to be described later, the gas path for preheating the mixed gas B in the preheating chamber is set, for example, to the same height as the preheating chamber, thereby preventing the mixed gas B from being excessively preheated like the mixed gas A. prevent. As a result, the reaction rate between NH ₃ contained in mixed gas B and Cr chloride gas and AlCl ₃ gas contained in mixed gas A is suppressed, and the hard coating becomes columnar particles.

The gas path for preheating the mixed gas B passes through the gas preheating section, but as described above, the preheating temperature is suppressed to avoid excessive preheating. As a means for preheating in this way, a Cr chloride gas generating part (a gas for obtaining mixed gas a1 passes), the first preheating section (the gas path for preheating the mixed gas a2 passes), the second preheating section (the gas path for preheating the mixed gas B passes), and further, the mixed gas The total length of the gas path for obtaining a1 (gas path for mixed gas a1) and the length of the gas path for preheating mixed gas a2 (gas path for mixed gas a2) is the gas path for preheating mixed gas B ( It is conceivable to lengthen the length in the range of 3 times or more, preferably 5 times or more, and 8 times or less than the gas path of the mixed gas B). This range may be appropriately determined depending on the device capacity, and may be 10 times, or even 20 times. As an example, the gas path for preheating the mixed gas B is preferably 650 mm or less, more preferably 550 mm or less. As a result, excessive reaction between NH ₃ gas and AlCl ₃ gas or Cr chloride gas is suppressed, and the hard coating has a structure composed of aggregates of columnar particles.
The gas path of the mixed gas for obtaining the mixed gas a1, the gas path for preheating the mixed gas a2, and the gas path for preheating the mixed gas B are completed after each mixed gas is introduced into the furnace. means the route to In other words, it refers to a connection path and a path in a preheating chamber (preheating chamber) that accompany rotation during film formation, such as the preheating section of the CVD furnace used in this embodiment, as will be described later.

<<Mixing of Mixed Gas A and Mixed Gas B and Introduction into Furnace>>
If mixed gas A and mixed gas B are mixed in advance and introduced into the CVD furnace (inside the reaction vessel) through one nozzle hole, the reaction rate between _NH3 gas and _AlCl3 gas or Cr chloride gas becomes too fast. , it becomes difficult to obtain a structure composed of aggregates of columnar particles in the hard coating. Therefore, the mixed gas A and the mixed gas B are not mixed before being introduced into the CVD furnace (into the reaction vessel). (inside the reaction vessel) independently. Specifically, for example, as will be described in the later-described manufacturing apparatus, the nozzle hole for the mixed gas B has a different ejection direction from the nozzle hole for the mixed gas A, and furthermore, the nozzle hole for the mixed gas A is more distant from the rotation axis than the nozzle hole for the mixed gas A. The distance between NH ₃ gas and AlCl ₃ gas or Cr chloride gas is prevented from becoming too fast.

<<Reaction Pressure and Film Forming Temperature>>
The reaction pressure for film formation is preferably 3 to 5 kPa. The reason for this is that if the reaction pressure is too low, the film formation rate will decrease, while if the reaction pressure is too high, the reaction will be accelerated, making it difficult to obtain a structure composed of aggregates of columnar particles.
Also, the temperature in the CVD furnace (inside the reaction vessel) is preferably 750 to 850.degree. The reason for this is that if the deposition temperature is too low, the amount of chlorine in the hard coating will increase and wear resistance will decrease. This is because it is difficult to obtain a structure that The temperature in the furnace is more preferably 770-820°C.

In the case of coating with carbonitride, a gas that provides a carbon component, that is, a hydrocarbon gas having 2 to 5 carbon atoms (C2 to C5) (eg, ethane) or a hydrogen carbonitride gas (eg, acetonitrile) is mixed. It is preferably introduced into the CVD furnace together with gas a2. By introducing highly reactive ethane or acetonitrile, the carbonitride can be stably coated. The introduction amount of the hydrocarbon gas is preferably 0.4% by volume or less with respect to the sum of the mixed gas A and the mixed gas B.

<Coating device>
In the chemical vapor deposition apparatus (CVD furnace) used in one embodiment of the present invention, in order to carry out the above-described manufacturing method, the temperature in the furnace (inside the reaction vessel) is 750 to 850 ° C., and the pressure in the furnace (inside the reaction vessel) is It can be made to 3 to 5 KPa and has the following characteristic configuration. A specific configuration will be described in an embodiment to be described later, and here, the items to be provided as the apparatus will be mainly described.
The coating apparatus independently preheats three types of mixed gases, ie, a mixed gas for generating Cr chloride gas, which is a component of mixed gas A, mixed gas a2, and mixed gas B, and heats them in a CVD furnace (reaction vessel inside).

That is, the CVD furnace has a gas preheating section and a gas discharge section for introducing gas into the reaction vessel, which will be described later. The gas preheating part is
(1) a Cr chloride gas generating unit that brings a mixed gas for generating Cr chloride gas into contact with metal Cr to generate a mixed gas a1 containing Cr chloride gas;
(2) a first preheating unit that preheats the mixed gas a2;
(3) a second preheating section for preheating the mixed gas B, and
(4) a mixing unit for mixing mixed gas a1 and mixed gas a2 to obtain mixed gas A;
and
The heat source for the preheating section may be provided independently for the preheating section, or a heat source (heater) provided on or near the peripheral wall of the CVD furnace may be used. Also, the metal Cr is formed in a shape such as flakes that easily generates Cr chloride gas.

Here, when the heat source of the CVD furnace is used as a means for adjusting the temperature of the mixed gas as described above in the preheating section, for example, the heater of the CVD furnace, which is the preheating source, generates Cr chloride gas. part (through which the gas path for obtaining the mixed gas a1 passes), a first preheating part (through which the gas path of the mixed gas a2 passes), and a second preheating part (through which the gas path of the mixed gas B passes) As an example, the length of the gas path for obtaining the mixed gas a1 (the gas path of the mixed gas a1) and the length of the gas path for preheating the mixed gas a2 (the length of the mixed gas a2) are devised. The total length of the gas path) is 3 times or more, preferably 5 times or more and 8 times or less, the length of the gas path for preheating the mixed gas B (gas path of the mixed gas B). is mentioned.
Here, the length of the gas path for obtaining the mixed gas a1, the length of the path for preheating the mixed gas a2, and the length of the path for preheating the mixed gas B are respectively the gas preheating from the gas inlet of the CVD furnace. It means the length to the exit of the part. That is, it refers to a connection path and a path in a preheating chamber (preheating chamber) that are accompanied by rotation during film formation, such as the preheating section of the CVD furnace used in the examples, as will be described later.

With such a configuration, the mixed gas a1 is preheated to 750° C. or higher, while the mixed gas a2 introduced from the gas path 81 is heated to a temperature in the vicinity of the mixed gas a1, for example, within a range of ±80° C. It can be preheated and mixed with the mixed gas a1 in the mixing chamber 63 to form the mixed gas A. On the other hand, the temperature of the mixed gas B introduced from the mixed gas path 91 is lower than that of the mixed gas A.
In addition, since the gas path in the preheating section is long, the mixed gas A rises to about the temperature in the furnace. On the other hand, it can be said that the temperature rise of the mixed gas B is suppressed because the gas path in the preheating section is shortened.

Furthermore, in the CVD furnace, a first pipe provided with a nozzle hole for introducing the mixed gas A into the reaction vessel and a nozzle hole for introducing the mixed gas B into the reaction vessel were provided as gas discharge parts. It has a second pipe. For example, two second pipes are arranged so as to face the outside of one first pipe, and these pipes rotate about the axis of the first pipe at a speed of 2 to 5 revolutions/minute. It is desirable to rotate.
Here, if the nozzle hole for the mixed gas A and the nozzle hole for the mixed gas B are too close, a rapid reaction will occur, making it difficult to obtain a structure composed of aggregates of columnar particles, and the film thickness distribution of the hard coating will be affected. Deteriorate. On the other hand, if the nozzle hole for the mixed gas A and the nozzle hole for the mixed gas B are too far apart, the gas supply becomes insufficient and the film thickness distribution deteriorates. Therefore, as an example, as shown in FIG. 8, the distance between the nozzle hole of the mixed gas A and the rotation axis (the axis of the first pipe) is H1, and the nozzle hole of the mixed gas B and the rotation axis (the first pipe) When H2 is the distance from the center of the center), H2/H1 is preferably 1.5 or more.
Furthermore, it is preferable that the gas ejection direction from the nozzle hole of the mixed gas A and the gas ejection direction from the nozzle hole of the mixed gas B are deviated from each other by 30 to 90 degrees.

The present invention will be described below with reference to examples applied to coated cutting tools, but the present invention is not limited to these examples.

<Coating device>
In this example, a chemical vapor deposition apparatus (CVD furnace) 1 shown in FIGS. 6, 7 and 8 as schematic diagrams was used. An outline of this device will be described.
The CVD furnace 1 has a cylindrical chamber 2, a heater 3 provided inside the peripheral wall of the chamber 2, and a plurality of insert installation plates 4 for installing a large number of insert base materials (tool base materials) 20 in the chamber 2. It has a reaction vessel 5, a connection path 11 provided at the bottom of the reaction vessel 5, and a preheating chamber 6 as a preheating section.
The preheating chamber 6 is
A mixed gas for generating Cr chloride gas introduced from the gas passage 82 is dispersed in the lower part of the cylindrical preheating chamber 6 via the connecting passage 11 to form a Cr chloride gas generating chamber 62 (chloride gas generating chamber 62). a space to be introduced into the gas generation section);
A Cr chloride gas generation chamber 62 provided directly above this space, having a cylindrical space whose outer circumference coincides with the outer circumference of the preheating chamber 6 and whose central portion is cylindrical, and which is concentric with the preheating chamber 6;
a preheating chamber 61 (first preheating section) which is formed concentrically with the preheating chamber 6 in a cylindrical space at the center of the Cr chloride gas generating chamber 62 and preheats the mixed gas a2 introduced from the gas path 81;
a mixing chamber 63 (mixing section) located above the Cr chloride gas generating chamber 62 and the preheating chamber 61 and mixing a mixed gas a1 and a mixed gas a2 to be described later to form a mixed gas A;
have.
In addition, the axial center of the preheating chamber 6, that is, the preheating chamber 61, has a path (second preheating section) through which the mixed gas B introduced from the gas path 91 penetrates in the height direction. At the top of the chamber 6 it is connected to the central passage of the pipe 7, which has the shortest length (550 mm) passing through the preheating section. On the other hand, the path of the mixed gas A mixed in the mixing chamber 63 is provided to connect to the outer path 2 of the pipe 7 above the preheating chamber 6 .

The mixed gas introduced from the gas path 82 is introduced into the Cr chloride gas generation chamber 62 in the preheating chamber 6, reaches the furnace temperature of 750° C. or higher, and reacts with metal Cr in the generation chamber to generate Cr chloride gas. and is introduced into the mixing chamber 63 .
Then, as described above, the mixed gas B is introduced into the outer path of the pipe 7 and into the reaction vessel 5 through the nozzle holes 91a and 91b. On the other hand, the reaction gas A introduced through the gas paths 81 and 82 and passing through the preheating chamber 61 is introduced into the central path of the pipe 7 and introduced into the reaction vessel 5 through nozzle holes 83a and 83b.
Here, the positional relationship between the nozzle holes 83a, 83b and the nozzle holes 91a, 91b is such that the nozzle holes 91a, 91b are closer to the rotation axis of the pipe 7 than the nozzle holes 83a, 83b, as shown in the cross-sectional view of the gas ejection port in FIG. When the distance between the nozzle holes 91a and 91b and the rotation axis O1 is H2, and the distance between the nozzle holes 83a and 83b and the rotation axis O1 is H1, H2/H1 is 2. The ejection direction of the nozzle holes 91a and 91b forms an angle of 90 degrees with the ejection direction of the nozzle holes 83a and 83b.
The connecting path 11 and preheating chamber 6 and pipe 7, shown at 12 in FIG. Illustration of such a configuration is omitted.

6 and 7, the illustration of the specific configuration is omitted, but the total length of the length of the gas path for obtaining the mixed gas a1 and the length of the gas path for preheating the mixed gas a2 is is about four times the length of the gas path for preheating the mixed gas B, which is the sum of 13a, 13b and 13c shown in FIG.

≪Base material≫
As a base material, a milling insert (WDNW14520 manufactured by Mitsubishi Hitachi Tool Engineering) made of a WC-based cemented carbide (10% by mass of Co, 0.6% by mass of Cr ₃ C ₂ , the balance being WC and unavoidable impurities); , WC-based cemented carbide (7 wt.% Co, 0.6 wt.% _Cr3C2 , 2.2 wt.% ZrC, 3.3 _wt .% TaC, 0.2 wt.% NbC, balance WC and inevitable impurities) for physical property evaluation (ISO standard SNMN120408) was prepared.

≪Covering of intermediate film≫
For Examples 1 to 3 and Comparative Example 1, a titanium nitride film was formed as an intermediate film. First, the substrate was set in the CVD furnace 1 shown in FIG. 6, and the temperature inside the CVD furnace 1 was raised to 800° C. while H ₂ gas was being supplied. Then, at 800 ° C and 12 kPa, from the gas inlet of the preheating chamber 6 through the gas path 81, 83.1 vol% _H2 gas, 15.0 vol% _N2 gas, 1.9 vol% _TiCl4 A mixed gas composed of gases was introduced into the preheating chamber 62 and flowed into the reaction vessel 5 from the first nozzle holes 83a and 83b of the pipe 7 at a flow rate of 67 L/min to form a titanium nitride film having a film thickness shown in Table 1. bottom.

≪Covering of hard film≫
<<Step of obtaining mixed gas a1>>
After the pressure in the CVD furnace 1 was lowered to 4 KPa while flowing H ₂ gas, a mixed gas of H ₂ gas and HCl gas kept at 400° C. was introduced into the gas path 82 of the preheating chamber 6 shown in FIG.
The Cr chloride gas generation chamber 62 of the preheating chamber 6 preheated to 800° C. is filled with Cr metal flakes (purity 99.99%, size 2 mm to 8 mm), and H ₂ gas and HCl gas introduced from the gas path 82 are filled. to generate a mixed gas a1 of H ₂ gas and Cr chloride gas, which was introduced into the mixing chamber 63 .

<<Step of obtaining mixed gas A and introducing it into a reaction vessel through a nozzle hole>>
A mixed gas a2, which is a mixture of H ₂ gas and AlCl ₃ gas, was introduced into the preheating chamber 62 from the gas inlet of the preheating chamber 6 through the gas path 81 and preheated.
Then, the mixed gas a1 and the mixed gas a2 are mixed in the mixing chamber 63 to obtain the mixed gas A having a temperature near 800° C., which is the temperature of the preheating chamber. Then, the obtained mixed gas A was introduced into the reaction vessel furnace through the first nozzle holes 83 a and 83 b of the pipe 7 . The total flow rate of mixed gas A was 48.75 L/min.

<<The step of introducing the mixed gas B into the reaction vessel through the nozzle hole>>
A mixed gas B composed of H ₂ gas, N ₂ gas and NH ₃ gas was introduced into the gas path 91 and introduced into the furnace through the second nozzle holes 91 a and 91 b of the pipe 7 . The total flow rate of mixed gas B was 30.25 L/min.
Here, when the value of NH ₃ /(AlCl ₃ +CrCl ₃ ) is in the range of 0.18 to 0.39, excessive reaction between NH ₃ gas and halogen gases such as CrCl ₃ gas and AlCl ₃ gas is more likely to occur. This can be suppressed more reliably, and a hard coating containing nitrides based on Al and Cr can be stably formed.

Thus, in Examples 1 to 3 and Comparative Example 1, nitridation of Al and Cr having a film thickness of about 4 μm was performed on the intermediate film shown in Table 1 by chemical vapor deposition using each mixed gas composition shown in Table 2. A coated cutting tool was made by coating an object. Here, in Comparative Example 1, the value of NH ₃ /(H ₂ +N ₂ ) essential for producing the hard coating of the present invention does not satisfy the preferred range, and furthermore, NH ₃ /(AlCl ₃ +CrCl ₃ ) is also outside the preferred range.
The amount of Cr chloride gas and AlCl ₃ gas generated was determined by setting the amount of Cr chloride gas to 1/3 of the amount of HCl gas to be introduced into the Cr chloride gas generation chamber to determine the composition of the mixed gas. Table 2 shows film formation conditions.

Comparative Example 2 was coated using an arc ion plating apparatus. An alloy target of Al ₇₀ Cr ₃₀ (numerical values are atomic ratios) was used without an intermediate film, a negative pressure bias voltage of −100 V was applied to the substrate, and nitrogen gas was introduced into the furnace to increase the furnace pressure. A coated cutting tool was manufactured by setting the pressure to 3 Pa and the temperature in the furnace to 500° C. and coating the nitride of Al and Cr to a thickness of about 4 μm.

Next, for Examples 1 to 3 and Comparative Examples 1 and 2, the composition of the hard coating, measurement of the crystal structure, and machinability evaluation were performed as follows.

≪Composition of hard coating≫
Using an electron probe microanalyzer (EPMA, JXA-8500F manufactured by JEOL Ltd.), under the conditions of an acceleration voltage of 10 KV, an irradiation current of 0.05 A, and a beam diameter of 0.5 μm, a cross section of an insert (SNMN120408) for physical property evaluation The composition of the hard coating was obtained from the average of the measured values obtained by measuring five arbitrary points in the center of the thickness direction of the aluminum chromium nitride hard coating. Table 3 shows the measurement results.

<<Measurement of crystal structure>>
Using an X-ray diffractometer (EMPYREAN manufactured by PANalytical), a CuKα1 ray (wavelength λ: 0.15405 nm) was applied to the surface of the hard coating on the rake face of the physical property evaluation insert (SNMN120408) at a tube voltage of 45 kV and a tube current of 40 mA. After irradiation, the crystal structure of the hard coating was evaluated.

The ICDD X-ray diffraction database was used to identify the diffraction peaks. Since there is no ICDD data for the fcc-structure aluminum chromium nitride hard coating, the ICDD file for the fcc-structure aluminum nitride hard film was used instead. The results are shown in Figures 1-5.

≪Cutting evaluation≫
The coated milling insert was attached to an indexable rotary tool (ASRT5063R-4) with a set screw, and the tool life of the hard coating was evaluated under the following milling conditions. The flank wear width of the hard coating was measured by observing with an optical microscope at a magnification of 100 times. The tool life was defined as the total cutting length when the maximum wear width of the flank exceeded 0.350 mm, and the machining time up to that point was measured in units of 5 minutes. Processing conditions are shown below. Table 3 shows the test results.
Work material: S55C (30HRC)
Machining method: Milling Insert shape: WDNW140520
Cutting speed: 150 m/min Rotation speed: 758 rpm Feed per tooth: 2.05 mm/tooth
Feed rate: 1554 mm/min Axial depth of cut: 1.0 mm
Radial depth of cut: 40mm
Cutting method: dry cutting

Examples 1 to 3 and Comparative Example 2 consisted of aggregates of columnar particles grown in the film thickness direction on the surface of the substrate, while Comparative Example 1 consisted of granular particles.
Here, description is added about Example 1. FIG. 9 and 10 are TEM photographs (magnification: 2,000,000 times) of the hard coating according to Example 1 and a schematic diagram thereof, respectively. As shown in FIGS. 9 and 10, in the hard coating according to Example 1, crystal grains having a part with a laminated structure and a part with a single layer structure were confirmed. It can be said to have a crystal grain with a portion.

Examples 1 to 3 exhibited stable wear patterns and extended tool life. On the other hand, Comparative Examples 1 and 2 had a shorter tool life.
Looking at the X-ray diffraction patterns of Examples 1 to 3 in FIGS. 1 to 3, it is confirmed that the peak intensity (count value) on the high angle side after the (311) plane is large in Examples 1 to 3. be. When the TB/TA value was evaluated, it was confirmed that Examples 1 to 3 had a TB/TA value of 0.40 or more, indicating relatively high peak intensity on the high angle side. From this, it is presumed that Examples 1 to 3 had a large peak strength on the high angle side and exhibited superior durability. The X-ray diffraction pattern of Comparative Example 1 is shown in FIG. 4, and the X-ray diffraction pattern of Comparative Example 2 is shown in FIG. In Comparative Examples 1 and 2, the TB/TA value was 0.2 or less, and it was confirmed that the peak intensity (count value) on the high angle side was relatively small, and it is presumed that sufficient durability was not exhibited. be.

Since the coated tool of the present invention has excellent durability, it can also be used as a cutting tool and a mold for press working or forging. It can also be applied to die-casting pins, inserts, and sliding parts that constitute various machines.

1: Chemical vapor deposition equipment (CVD furnace)
2: Chamber 3: Heater 4: Insert installation plate 5: Reaction vessel 5a: Opening of reaction vessel 6: Preheating chamber (preheating section)
61: Preheating chamber 62: Cr chloride gas generation chamber 63: Mixing chamber 7: Pipe (gas discharge part)
83a, 83b, 91a, 91b, 92a, 93a: Nozzle hole (gas ejection port)
81: Gas path of mixed gas a2 82: Gas path of mixed gas to be mixed gas a1 84: Gas path of mixed gas 91: Gas path of mixed gas B 92: Gas path of mixed gas 93: Gas path of mixed gas : Exhaust pipe 11: Connection path 12: Rotating part during film formation 13a: Gas path of mixed gas B in preheating chamber 13b: Gas path of mixed gas B in connection path (longitudinal direction)
13c: Gas path of mixed gas B in connection path (rotational axis direction)
20: Insert base material 31: Laminated portion 32: Single layer portion

Claims (2)

A coated tool having a hard coating on the surface of a base material,
The hard coating is a chemical vapor deposition film , and the average content ratio of Al is 50 atomic % or more, Cr is 10 atomic % or more, and the total content ratio of Al and Cr is 90 atomic % or more of nitride or carbonitride,
The hard coating is composed of an aggregate of columnar particles grown in the film thickness direction on the surface of the base material,
The hard coating has (111) plane, (200) plane, (220) plane, (311) plane, (222) plane, (400) plane, (331) plane, (420) plane and The (422) plane has a peak intensity, and the total peak intensity due to these crystal planes is TA, (311) plane, (222) plane, (400) plane, (331) plane, (420) plane and ( 422) where TB is the total peak intensity attributed to the plane, the value of TB/TA is 0.40 or more and 0.70 or less ,
A coated tool characterized in that an intermediate coating containing Ti nitride or carbonitride is provided between the base material and the hard coating. The hard coating has crystal grains having a single-layer structure portion with a relatively high Al content ratio and a laminated structure portion with a relatively low Al content ratio in a microstructure using a transmission electron microscope. 2. The coated tool of claim 1, wherein the coated tool is dispersed.

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