JP6910598B2 - Cover cutting tool - Google Patents

Description

The present invention relates to a coated cutting tool having a hard film made of a nitride containing Al and Cr coated by a chemical vapor deposition method on the surface of the tool.

Conventionally, in order to improve the life of a cutting tool, a coated cutting tool in which the surface of the tool is coated with a hard film by a physical vapor deposition method or a chemical vapor deposition method has been used. Among various hard films, the hard film made of nitrides of Al and Ti and the hard film made of nitrides of Al and Cr are film types with excellent wear resistance and heat resistance, and are widely used in coating cutting tools. There is.
For the formation of a hard film composed of Al and Ti nitrides, the physical vapor deposition method and the chemical vapor deposition method are widely applied to coating cutting tools actually sold on the market. On the other hand, regarding the formation of a hard film composed of Al and Cr nitrides, the physical vapor deposition method is actually applied to the coated cutting tools sold on the market, and the chemical vapor deposition method is not applied. Is the current situation.

For example, Patent Document 1 separately supplies a _{gas group A composed of NH 3} , N ₂ and H _2, and a gas group B composed of CrCl ₃ , AlCl ₃ , Al (CH ₃ ) ₃ , and N ₂ and H _2. This discloses that the surface of the tool base material is coated with a hard film made of nitrides of Al and Cr having a cubic structure.

JP-A-2017-80883

The coating described in Patent Document 1, according to the study of the present inventors, when coating hard film made of a nitride of Al and Cr in the chemical vapor deposition, and NH ₃ gas is an alkaline gas, a halogen gas CrCl ₃ gas and AlCl ₃ gas is excessively difficult react with film formation is stabilized, and further, it was confirmed that the durability of the coated cutting tool also not sufficient.

The cutting tool according to the embodiment of the present invention is
The hard film is a nitride containing 60 atomic% or more of Al and 10 atomic% or more of Cr with respect to the total amount of metal elements including metalloids, and the total content ratio of Al and Cr is 90 atomic% or more. ,
It is composed of a collection of columnar particles grown in the film thickness direction with respect to 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 due to the fcc structure Has peak intensity and
The total peak intensity due to the crystal plane is the total peak intensity due to the TA, (311) plane, (222) plane, (400) plane, (331) plane, (420) plane and (422) plane. In the case of TB, the value of TB / TA is 0.40 or more.

Further, in the cutting tool according to the above embodiment, the hard film has a single-phase structure having a relatively high Al content in a microstructure using a transmission electron microscope, and a relatively Al content. It is preferable that the crystal particles having a portion having a low product phase structure are dispersed.

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

It is a figure which shows the X-ray diffraction measurement result of Example 1. FIG. It is a figure which shows the X-ray diffraction measurement result of Example 2. It is a figure which shows the X-ray diffraction measurement result of Example 3. It is a figure which shows the X-ray diffraction measurement result of the comparative example 1. FIG. It is a figure which shows the X-ray diffraction measurement result of the comparative example 2. It is a schematic schematic diagram of the chemical vapor deposition apparatus (CVD furnace) used for coating the hard film of an Example. It is a schematic schematic diagram which enlarged the main part of the chemical vapor deposition apparatus (CVD furnace) used for coating the hard film of an Example. It is the schematic sectional drawing of the gas outlet of the chemical vapor deposition apparatus (CVD furnace) used for coating the hard film of an Example. 6 is an enlarged TEM photograph (magnification of 2,000,000 times) of the hard film of Example 1. It is a schematic schematic diagram of FIG.

The present inventor improves the durability of a nitride mainly composed of Al and Cr when it is used as a coating film for a coating cutting tool by increasing the X-ray diffraction peak intensity caused by the crystal plane on the high angle side. We found that and arrived at the present invention. That is, for nitrides mainly composed of Al and Cr, the X-ray diffraction peak intensities due to the (311) plane, (222) plane, (400) plane, (331) plane, (420) plane, and (422) plane. When the relative intensities of the total of these X-ray diffraction peaks were arranged by paying attention to the relative intensities of the above, we obtained a surprising finding that the durability of the coated cutting tool is improved when the total relative intensities of these X-ray diffraction peak intensities are above a certain level. ..
Further, in order to improve the durability and stabilize the film formation, the NH _{3 gas, which is an alkaline gas, and the CrCl 3} gas or AlCl ₃ gas, which are halogen gases, should not be excessively reacted, that is, in the mixed gas. It was also found _{that the ratio of the amount of NH 3} gas to the total amount of N ₂ gas and H ₂ gas should be specified, and that Cr chloride gas should be generated in the CVD furnace.
Hereinafter, the component composition, structure, crystal structure, characteristics, and details of the manufacturing apparatus of the hard film constituting the coated cutting tool according to the embodiment of the present invention will be described.

<Composition>
First, the composition of the hard film according to the present embodiment will be described.
The hard film according to this embodiment is a nitride based on Al and Cr. The Al and Cr nitride film is a film having excellent wear resistance and heat resistance.

<< Aluminum Al >>
When the Al content ratio is high, the heat resistance of the hard film is increased, and a lubrication protective film is easily formed on the tool cutting edge, so that the durability of the coated cutting tool is improved. In order to sufficiently reproduce these effects, the hard film according to the present embodiment has an Al content ratio of 60 atomic% with respect to the total amount of metal elements including metalloids (hereinafter referred to as metal elements). That's all. Furthermore, it is preferable that the Al content ratio is 70 atomic% or more. However, if the Al content ratio becomes too high, the amount of AlN having a fragile hcp structure increases, and the durability of the coated cutting tool decreases. Therefore, the Al content ratio is preferably 90 atomic% or less.

<< Chromium Cr >>
If the Cr content is too small, the AlN of the fragile hcp structure increases too much, and the durability of the coated cutting tool decreases. In addition, it becomes difficult for a lubrication protective film to be formed on the tool edge, and welding is likely to occur. Therefore, the Cr content ratio is set to 10 atomic% or more. Furthermore, the Cr content ratio is preferably 15 atomic% or more. However, if the Cr content ratio becomes too high, the Al content ratio relatively decreases and the heat resistance decreases. Therefore, the Cr content ratio is preferably 30 atomic% or less.

<< Other elements >>
The hard film according to the present embodiment has a total content ratio of Al and Cr of 90 atomic% or more in order to impart higher heat resistance to the hard film. Furthermore, it is preferable that the total content ratio of Al and Cr is 95 atomic% or more. The hard film according to this embodiment may contain metal elements other than Al and Cr, for example, Ti, Si, Zr, B, and V. These elements are elements generally added to AlTi-based nitrides and AlCr-based nitrides, and if added in a small amount, the durability of the coated cutting tool is not significantly reduced. That is, in a nitride having a total content ratio 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 will be described later. ) As long as the relative strength of the total peak strength caused by the surface is a certain value or more, the durability of the coated cutting tool is not significantly reduced even if these metal elements are contained. However, if the content ratio of the metal element other than Al and Cr becomes too high, the basic characteristics of the nitride based on Al and Cr deteriorate, and the durability of the coated cutting tool deteriorates. Therefore, when other metal elements are contained, the content ratio is set to 10 atomic% or less.

<< Inevitable Impurities >>
The hard film according to the present embodiment may contain components contained in the film-forming gas such as oxygen, carbon and chlorine as unavoidable impurities up to 1% by mass or less when the entire hard film is 100% by mass. If the hard film according to the present embodiment is a nitride as a whole, oxides, composite carbides based on Al and Cr, composite carbonitrides, and the like may be partially contained due to these impurities. ..

<Crystal structure>
The hard coating according to the present embodiment has a (111) plane, a (200) plane, a (220) plane, a (311) plane, a (222) plane, a (400) plane, a (331) plane, and a (331) plane, which are caused by the fcc structure. It has peak intensities on the 420) and (422) planes.
If it has a peak intensity due to these fcc structures, it may have a peak intensity due to the hcp structure in part. However, if the peak strength due to the hcp structure becomes too large, the durability of the coated cutting tool decreases.
Therefore, even when the hcp structure is contained, it is preferable that the maximum peak intensity of the peak caused by the hcp structure is 1/10 or less of the maximum peak intensity of the peak caused by the fcc structure.

The hard film according to the present embodiment has a (111) plane, a (200) plane, a (220) plane, a (311) plane, a (222) plane, a (400) plane, and a (331) plane having an fcc structure in X-ray diffraction. It has peak intensities on at least nine faces, (420) and (422) faces. By having the peak strength on the (422) surface on the higher angle side, the durability of the coated cutting tool is improved. Normally, a nitride mainly composed of Al and Cr coated by the arc ion plating method tends to have relatively high peak intensities on the (111) plane, (200) plane, and (220) plane on the low angle side. be. The present inventor has described the (311) plane, (222) plane, (400) plane, and (331) plane on the high angle side in a nitride mainly composed of Al and Cr coated by a chemical vapor deposition method in which the film forming conditions are devised. It was found that the durability of the coated cutting tool is improved by increasing the relative strength of the total of the peak intensities caused by the (420) and (422) surfaces.
Regarding the nitride mainly composed of Al and Cr coated by the chemical vapor deposition method, the (111) plane, (200) plane, (220) plane, (311) plane, (222) plane, and (400) plane of the fcc structure , (331) plane, (420) plane and (422) plane, total peak intensity due to TA, (311) plane, (222) plane, (400) plane, (331) plane, (420) plane and (422) When the total peak intensity due to the surface is TB, the durability of the coated cutting tool can be improved by setting the TB / TA value to 0.40 or more. Preferably, the TB / TA value is 0.50 or more. More preferably, the TB / TA value is 0.55 or more. Even if the peak intensities of the (111), (200), and (220) planes on the low angle side are too low, the basic characteristics of the hard film deteriorate, so the TB / TA value may be 0.70 or less. preferable.

Since there is no diffraction peak of aluminum nitride in the ICDD file, the diffraction peak intensity of each crystal plane is obtained from the aluminum nitride having an fcc structure described in ICDD file No. 00-025-1495. Further, although the ICDD file number 00-025-1495 does not have the peak intensity of the (422) plane, the peak intensity of the (422) plane can be confirmed in the X-ray diffraction pattern by calculating the plane spacing d value.
The X-ray diffraction peak of the aluminum nitride hard film is similar to the X-ray diffraction peak of the titanium aluminum nitride hard film, and the peak positions overlap. Therefore, when the hard film according to the present invention and the titanium aluminum nitride hard film are laminated, for example, alternately laminated, the TB / TA value can be calculated by using the obtained X-ray diffraction peak as the peak of the aluminum nitride hard film. good.

<Columnar particles>
The hard film according to the present embodiment is composed of a set of columnar particles grown in the film thickness direction with respect to the surface of the base material. The durability of the coated cutting tool is improved by forming the hard film made of nitrides based on Al and Cr into columnar particles grown in the film thickness direction with respect to the surface of the base material.
The average width of the columnar particles on the surface side is preferably 0.1 μm or more and 2.0 μm or less. By setting the average width on the surface side to 0.1 μm or more, the durability of the coated cutting tool is further enhanced. Further, when the average width on the surface side is 2.0 μm or less, the hard film is less likely to be plastically deformed, and the particle size falling off from the hard film is reduced, so that tool wear is easily suppressed.

The surface side in the present embodiment means the vicinity of the surface of the hard film on the side in contact with the work material, for example, the vicinity of the CP (Cross-section Policer) processed surface. The width of the columnar particles of the hard film can be measured by observing the cross section with a transmission electron microscope or a scanning electron microscope. The measurement location was set at a depth of 0.5 μm from the film surface on the side in contact with the work material. By observing the widths of 30 or more consecutive columnar particles, the average value of the particle widths converges. Therefore, the average width of the columnar particles of the hard film may be obtained from 30 or more continuous columnar particles.

<Micro tissue>
The microstructure of the hard film according to the present embodiment is not particularly limited, but it is preferable that crystal particles in which a single-phase structure and a product-phase structure coexist are dispersed in one particle. Specifically, for example, in one crystal particle, nitrides of Al and Cr having a relatively high content of Al and nitrides of Al and Cr having a relatively low content of Al are alternately laminated. A case where crystal particles having a portion having a product phase structure and a portion having a single-phase structure of a nitride of Al and Cr having a high Al content are dispersed in a microstructure (corresponding to Example 1 described later). (See FIGS. 9 and 10).
It is presumed that the single-phase structure portion has less distortion than the product-phase structure portion. Therefore, having a single-phase structure portion improves the durability of the coated cutting tool. The AlN content of the part having a product phase structure is relatively smaller than that of the part having a single phase structure, so that the Al content of the crystal particles as a whole increases too much and the AlN having a fragile hcp structure. Is suppressed from increasing. The presence of such particles enhances the wear resistance and heat resistance of the hard film as a whole, and can exhibit excellent durability.
The microstructure of the hard film according to this embodiment may have crystal particles having only a single-phase structure. Further, it may have crystal particles having only a laminated structure. It may have crystal particles having only a single-phase structure, crystal particles having only a laminated structure, and crystal particles having a single-phase structure and a product-phase structure coexisting.

In the part of the product phase structure, the nitrides of Al and Cr having a relatively high Al content ratio preferably have an Al content ratio of 60 atomic% or more, and have a relatively low Al content ratio. The Al and Cr nitrides preferably have an Al content of 55 atomic% or less.
In the part of the product phase structure, the nitrides of Al and Cr having a relatively high Al content ratio preferably have an Al content ratio of 70 atomic% or more, and further preferably 80% atomic% or more. preferable. However, if the Al content ratio becomes too high, AlN in the hcp structure increases, so the Al content ratio is preferably 95 atomic% or less. Further, it is preferably 90 atomic% or less.
In the part of the product phase structure, the nitrides of Al and Cr having a relatively low Al content ratio preferably have an Al content ratio of 50 atomic% or less, and further preferably 40 atomic% or less. preferable. However, if the Al content ratio becomes too low, the heat resistance of the entire hard film decreases, so the Al content ratio is preferably 10 atomic% or more. Further, 20 atomic% or more is preferable.
The single-phase structure portion preferably has an Al content of 60 atomic% or more. Furthermore, the Al content ratio is preferably 70 atomic% or more. However, if the Al content ratio becomes too high, AlN in the hcp structure increases, so that it is more preferably 90 atomic% or less.

<Average layer thickness>
The average layer thickness of the hard film according to this embodiment is preferably 1.0 to 15.0 μm. The reason is that if it is less than 1.0 μm, it is thin and therefore does not give a sufficient tool life, while if it exceeds 15.0 μm, it becomes too thick and the cutting accuracy may be lowered. The lower limit of the film thickness is preferably 2.0 μm, more preferably 3.0 μm, and even 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 cutting tool of the present embodiment, in order to further improve the adhesion of the hard film to the base material, for example, a nitride, a carbide, a nitride, etc. An interlayer film made of any of the carbides may be provided. The interlayer film is preferably a nitride of Al and Ti having excellent adhesion to the base material and the hard film.
Further, an upper layer having a different component ratio and a different composition from the hard film according to the present embodiment may be provided on the hard film according to the present embodiment. The upper layer is, for example, an oxide such as nitride, carbonitride, carbide or alumina, and may be provided via a bonding layer. Of these, alumina, which is generally used as a coating layer for forming a film by a chemical vapor deposition method, is preferable because it improves the heat resistance of the coating cutting tool. For example, in general, a coated cutting tool provided with alumina is used in the cutting process of a casting. It is preferable that the coated cutting tool of the present invention is also provided with alumina as an upper layer, if necessary, because the durability is further improved.

<Cutting edge treatment after coating>
Since the hard film according to the present embodiment has tensile stress because it is formed by chemical vapor deposition, it is preferable to perform post-coating cutting edge treatment that releases stress by a blasting device or the like after coating. By performing this cutting edge treatment after coating, chipping resistance is improved and a hard film with excellent tool life is obtained.

<Manufacturing method>
In the hard film according to the present embodiment, for example, the mixed gas A and the mixed gas B described below are separately introduced into a chemical vapor deposition apparatus (CVD furnace) in which the internal temperature is raised to 750 ° C. or higher, which will be described later. By mixing in the device, it is possible to coat a tool base such as an insert base material previously placed in the device.

<< Mixed Gas A >>
In the present embodiment, the mixed gas A includes a mixed gas a1 and a mixed gas a2. Mixed gas a1 is the HCl gas and H ₂ gas (also referred to as "mixed gas for obtaining the mixed gas a1" or "mixed gas to produce chloride Cr"), of the gas the 2 contacts the metal Cr This is a gas _{containing Cr chloride gas (not only a component that can be expressed by CrCl 3} but also a gas in which Cr and Cl are chemically bonded), and a typical composition is Cr / H _{2 chloride in terms of volume ratio.} = 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 a typical composition is AlCl ₃ / (H ₂ + N ₂ ) = 0.0006 to 0.0300 in terms of volume ratio.
The volume% of the volume%, and AlCl ₃ gas chloride Cr gas, as described below, was estimated from HCl gas amount to be introduced in order to generate these gases.
In the mixed gas a1, although HCl gas and H ₂ gas for the production of chloride Cr gas is contacted with the heated metal Cr, the heat, as described later in the description of the manufacturing apparatus, the inside of the CVD furnace It is desirable to do it in the gas preheating section. Further, it is desirable to obtain the mixed gas A by mixing the mixed gas a1 having Cr chloride gas with the mixed gas a2 heated to a temperature close to the temperature of the mixed gas a1. By doing so, it becomes easy to generate Cr chloride gas without being affected by _{AlCl 3 gas.}
The temperature at which the Cr chloride gas is generated in the gas preheating section is set to a temperature at which Cr chloride gas of about 750 ° C., which is the minimum set temperature of the furnace temperature, is stably generated. The reason is that if this temperature is too low, the amount of Cr chloride gas generated decreases, the entire hard film becomes Al-rich, and the hcp structure tends to increase.
_{Further, the AlCl 3} gas contained in the mixed gas a2 can be generated by introducing, for example, _{a mixed gas of H 2 gas and an HCl gas into an AlCl 3} gas generator filled with metal Al and kept at 330 ° C. It is preheated when it is mixed with the mixed gas a1 to form the mixed gas A. The temperature of the mixed gas a2 is preferably not so different from the temperature of the mixed gas a1 because the hard film becomes columnar particles, and is preferably in the vicinity of the temperature of the mixed gas a1 (for example, ± 80 ° C.).
In the mixed gas A obtained by mixing the mixed gas a2 with the mixed gas a1, it is desirable to maximize the flow rate _{of the H 2 gas.} It may further contain N ₂ gas and Ar gas in the gas mixture a1 and mixed gas a2.

<< Mixed Gas B >>
The mixed gas B includes H ₂ gas, N ₂ gas and NH ₃ gas. The composition ratio of this mixed gas B is 0.002 or more and 0.020 or less in the value of b2 / b1 when _{the total volume% of the N 2} gas and the H ₂ gas is b1 and the volume% of the NH _{3 gas is b2.} It is necessary to have the composition of the hard film according to the present embodiment. If the composition ratio of the mixed gas B is within the range of this composition ratio, it is possible to prevent the _{NH 3 gas, which is an alkaline gas, from excessively reacting with the CrCl 3} gas or AlCl ₃ gas, which are halogen gases.
This mixed gas B is also preheated, but the temperature rise due to the preheating is suppressed, and the temperature rise is suppressed to be lower than the temperature of the mixed gas A to avoid excessive preheating.
By setting the gas path for preheating the mixed gas B in the preheating chamber to be the same as the height of the preheating chamber, for example, it is possible to prevent the mixed gas B from being excessively preheated like the mixed gas A. _{As a result, the reaction rate between NH 3} contained in the mixed gas B and the _{Cr chloride gas and AlCl 3} gas contained in the mixed gas A is suppressed, and the hard film 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 and excessive preheating is avoided. As one means for preheating in this way, as described later, in order to obtain a Cr chloride gas generating portion (mixed gas a1) as a heat source for preheating, as in the preheating portion of the CVD furnace used in the present embodiment. The gas path passes through), the first preheating section (the gas path that preheats the mixed gas a2 passes), the second preheating section (the gas path that preheats the mixed gas B passes), and so on. The total 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 gas path of the mixed gas a2) is the sum of the lengths of the gas path for preheating the mixed gas B. It is conceivable to make it longer than (gas path of mixed gas B) by 3 times or more, preferably 5 times or more, and 8 times or less. This range may be appropriately determined depending on the capacity of the device, 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, _{the excessive reaction between the NH 3} gas and the AlCl ₃ gas or Cr chloride gas is suppressed, and the hard film becomes 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 such that the preheating ends after each mixed gas is introduced into the furnace. The route to. That is, as described later, it refers to a connection path that involves rotation during film formation and a path in the preheating chamber (preheating chamber), such as the preheating portion of the CVD furnace used in the present embodiment.

<< Mixing of mixed gas A and mixed gas B and introduction into the furnace >>
Further, when the mixed gas A and the mixed gas B are mixed in advance and introduced into the CVD furnace (inside the reaction vessel) from one nozzle hole _{, the reaction rate between the NH 3} gas and the AlCl ₃ gas or Cr chloride gas becomes faster. Therefore, it becomes difficult to obtain a structure composed of aggregates of columnar particles in the hard film. Therefore, the mixed gas A and the mixed gas B are not mixed before being introduced into the CVD furnace (inside the reaction vessel), and the nozzle hole of the mixed gas A and the nozzle hole of the mixed gas B are separately provided in the CVD furnace. Introduce independently into (inside the reaction vessel). Specifically, for example, as described in the manufacturing apparatus described later, the nozzle hole of the mixed gas B changes the ejection direction from the nozzle hole of the mixed gas A, and further, from the rotation axis rather than the nozzle hole of the mixed gas A. _{The reaction rate between the NH 3} gas and the AlCl ₃ gas or Cr chloride gas should not be too fast by arranging the distances on the outside.

<< Reaction pressure and film formation temperature >>
The reaction pressure for film formation is preferably 3 to 5 kPa. The reason is that if the reaction pressure is too low, the film formation rate decreases, while if the reaction pressure is too high, the reaction is promoted and it is difficult to obtain a structure composed of aggregates of columnar particles.
The temperature inside the CVD furnace (inside the reaction vessel) is preferably 750 to 850 ° C. The reason is that if the film formation temperature is too low, the amount of chlorine in the hard film increases and the wear resistance decreases, while if the film formation temperature is too high, the reaction is promoted and it is composed of aggregates of columnar particles. This is because it is difficult to obtain an organization. The temperature inside the furnace is more preferably 770 to 820 ° C.

<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-mentioned 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 set to 3 to 5 KPa and has the following characteristic configuration. A specific configuration will be described in Examples described later, and here, items to be provided as an apparatus will be mainly described.
The coating device independently preheats each of the three types of mixed gas, the mixed gas, the mixed gas a2, and the mixed gas B for generating Cr chloride gas, which is a component of the mixed gas A, in the CVD furnace (reaction vessel). It has a configuration to be introduced in).

That is, the CVD furnace has a gas preheating unit and an outgassing unit for introducing gas into the reaction vessel described later. The gas preheating part
(1) A Cr chloride gas generating unit that generates a mixed gas a1 containing a Cr chloride gas by bringing a mixed gas for generating a Cr chloride gas into contact with a metal Cr.
(2) First preheating section for preheating the mixed gas a2,
(3) A second preheating section that preheats the mixed gas B, and
(4) A mixing section in which the mixed gas a1 and the mixed gas a2 are mixed to form a mixed gas A.
And have.
The heat source of the preheating unit may be independently provided for the peripheral wall or its vicinity for the preheating part, or a heat source (heater) provided in or near the peripheral wall of the CVD furnace may be used. Further, the metal Cr has a shape such as flakes in which Cr chloride gas is likely to be generated.

Here, when the heat source of the CVD furnace is used as one means for adjusting the temperature of the mixed gas as described above in the preheating section, for example, Cr chloride gas is generated in the heater of the CVD furnace which is the preheating source. Part (the gas path for obtaining the mixed gas a1 passes), the first preheating part (the gas path of the mixed gas a2 passes), and the second preheating part (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 gas path for preheating the mixed gas a2 (mixed gas a2) are made by approaching them in order and devising the arrangement of the gas paths. The total length of the gas path) may be 3 times or more, preferably 5 times or more and 8 times or less the length of the gas path (gas path of the mixed gas B) for preheating the mixed gas B. Can be mentioned.
Here, the length of the gas path for obtaining the mixed gas a1 and the length of the path for preheating the mixed gas a2 and the length of the path for preheating the mixed gas B are gas preheating from the gas inlet of the CVD furnace, respectively. The length to the exit of the department. That is, as described later, it refers to a connection path that involves rotation during film formation and a path in the preheating chamber (preheating chamber), such as the preheating portion of the CVD furnace used in the examples.

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 in the vicinity of the mixed gas a1, for example, in the range of ± 80 ° C. It can be preheated and mixed with the mixed gas a1 in the mixing chamber 63 to obtain the mixed gas A. On the other hand, the mixed gas B introduced from the mixed gas path 91 has a lower temperature than the mixed gas A.
Since the gas path in the preheating section of the mixed gas A is long, the temperature of the mixed gas A has risen to about the temperature inside the furnace. On the other hand, with respect to the mixed gas B, since the gas path in the preheating portion is shortened, it can be said that the temperature rise is suppressed.

Further, 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 are provided as gas discharge parts. It has a second pipe. There are two second pipes, which are arranged so as to face the outside of one first pipe, and these pipes rotate at a speed of 2 to 5 rotations / minute around the axis of the first pipe. Is desirable.
Here, if the nozzle hole of the mixed gas A and the nozzle hole of the mixed gas B are too close to each other, a rapid reaction occurs, it becomes difficult to obtain a structure composed of aggregates of columnar particles, and the film thickness distribution of the hard film becomes difficult. become worse. On the other hand, if the nozzle hole of the mixed gas A and the nozzle hole of the mixed gas B are too far apart, the gas supply becomes insufficient and the film thickness distribution becomes poor. Therefore, as an example, as shown in FIG. 8, the distance from the nozzle hole of the mixed gas A and the rotating shaft (the axis of the first pipe) is H1, the nozzle hole of the mixed gas B and the rotating shaft (the first pipe). When the distance from the axis) is H2, H2 / H1 is preferably 1.5 or more.
Further, it is preferable that the gas ejection direction of the mixed gas A from the nozzle hole and the gas ejection direction of the mixed gas B from the nozzle hole are arranged so as to deviate from 30 degrees to 90 degrees.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

<Coating device>
In this embodiment, the chemical vapor deposition apparatus (CVD furnace) 1 shown in FIGS. 6, 7 and 8 was used as a schematic schematic diagram. The 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 in the lower part of the reaction vessel 5, and a preheating chamber 6 which is a preheating section.
The preheating chamber 6 is
A mixed gas for generating Cr chloride gas introduced from the gas path 82 is dispersed in the radial direction of the preheating chamber 6 via the connection path 11 in a cylindrical shape, and the Cr chloride gas generation chamber 62 (chloride) is dispersed. The space to be introduced into the gas generator)
A Cr chloride gas generation chamber 62, which is provided directly above this space, has a cylindrical space in the center where the outer circumference of the cylinder coincides with the outer circumference of the preheating chamber 6, and is concentric with the preheating chamber 6.
A preheating chamber 61 (first preheating unit) that is formed concentrically with the preheating chamber 6 in the cylindrical space at the center of the Cr chloride gas generation 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 generation chamber 62 and the preheating chamber 61 and mixing the mixed gas a1 and the mixed gas a2, which will be described later, to form a mixed gas A.
have.
Further, in the preheating chamber 6, that is, the axial center portion of the preheating chamber 61, there is a path (second preheating section) through which the mixed gas B introduced from the gas path 91 penetrates in the height direction thereof, and this path is preheated. The upper part of the chamber 6 is connected to the central path of the pipe 7, which has the shortest length (550 mm) of passing through the preheating portion. On the other hand, the path of the mixed gas A mixed in the mixing chamber 63 is provided so as to be connected to the outer path of 2 of the pipe 7 at the upper part of 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, reacts with the metal Cr in the generation chamber, and reacts with the metal Cr in the generation chamber to produce the Cr chloride gas. It becomes the mixed gas a1 containing the above, 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 is introduced into the reaction vessel 5 from the nozzle holes 91a and 91b. On the other hand, the reaction gas A introduced from the gas paths 81 and 82 and penetrating the preheating chamber 61 is introduced into the central path of the pipe 7 and introduced into the reaction vessel 5 from the nozzle holes 83a and 83b.
Here, as shown in the gas ejection port cross-sectional view of FIG. 8, the positional relationship between the nozzle holes 83a and 83b and the nozzle holes 91a and 91b is such that the nozzle holes 91a and 91b have a rotation axis of the pipe 7 rather than the nozzle holes 83a and 83b. H2 / H1 is 2 when the distance between the nozzle holes 91a and 91b and the rotating shaft O1 is H2 and the distance between the nozzle holes 83a and 83b and the rotating shaft O1 is H1. The ejection directions of the nozzle holes 91a and 91b and the ejection directions of the nozzle holes 83a and 83b form an angle of 90 degrees.
The connection path 11, the preheating chamber 6 and the pipe 7 shown in FIG. 12 are configured to rotate at a speed of 2 rotations / minute, but in FIGS. 6, 7 and 8, this rotation is necessary. The illustration of the configuration is omitted.

Although the specific configuration is not shown in FIGS. 6 and 7, 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 shown in FIG. It is configured to be 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 1.

≪Base material≫
As the substrate, WC based cemented carbide (10 mass% of Co, 0.6 wt% of _Cr 3 _{C 2,} balance WC and inevitable impurities) manufactured by milling insert (manufactured by Mitsubishi Hitachi Tool WDNW14520) and , WC based cemented carbide (7 wt% of Co, 0.6 wt% of _Cr 3 _C 2, 2.2 wt% of ZrC, 3.3 wt% of TaC, 0.2 wt% NbC, balance WC And an insert for physical property evaluation (ISO standard SNMN120408) made of (consisting of unavoidable impurities) was prepared.

≪Coating of interlayer film≫
In Examples 1 to 3 and Comparative Example 1, a titanium nitride film was formed as an intermediate film. First, the substrate was set in a CVD furnace 1 shown in FIG. 6, the temperature of the CVD furnace 1 is raised to 800 ° C. while introducing _{H 2} gas. Thereafter, at 800 ° C. and 12 kPa, from the gas inlet of the preheating chamber 6 through the gas passage 81, 83.1% by volume of _{H 2} gas, 15.0% by volume of _{N 2} gas, 1.9 volume% of TiCl ₄ A mixed gas composed of gas is 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 the thickness shown in Table 1. did.

≪Covering of hard film≫
<< Process of obtaining mixed gas a1 >>
After reducing the pressure in the CVD furnace 1 in 4KPa while introducing H ₂ gas, the gas path 82 of the preheating chamber 6 shown in FIG. 6, was introduced a mixed gas of H ₂ gas and HCl gas was kept to 400 ° C..
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. _{A mixed gas a1 which is a mixed gas of H 2} gas and Cr chloride gas was generated by reacting with the mixed gas of H 2 gas and Cr chloride gas, and introduced into the mixing chamber 63.

<< Process of obtaining mixed gas A and introducing it into the reaction vessel through the 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 to preheat.
Then, the mixed gas a1 and the mixed gas a2 were mixed in the mixing chamber 63 to obtain a 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 83a and 83b of the pipe 7. The total flow rate of the mixed gas A was 48.75 L / min.

<< Process of introducing mixed gas B into the reaction vessel from 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 was introduced into the furnace through the second nozzle holes 91a and 91b of the pipe 7. The total flow rate of the 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, the excess reaction _{between the NH 3} gas and the halogen gas CrCl ₃ gas or AlCl _{3 gas is caused.} It can be suppressed more reliably, and a hard film having a nitride based on Al and Cr can be stably formed.

In this way, in Examples 1 to 3 and Comparative Example 1, a coated cutting tool was produced by coating the interlayer film with Al and Cr nitrides having a film thickness of about 4 μm by a chemical vapor deposition method. _{Here, in Comparative Example 1, the value of NH 3} / (H ₂ + N ₂ ), which is indispensable for producing the hard film of the present invention, does not satisfy a predetermined range, and further, NH ₃ / (AlCl ₃ + CrCl _3). The value of) is also out of the desired range.
As for the amount of generated Cr chloride gas and AlCl ₃ gas, the composition of the mixed gas was determined by using 1/3 of the amount of HCl gas introduced into the Cr chloride gas generation chamber as the amount of Cr chloride gas. The film forming conditions are shown in Table 2.

Comparative Example 2 was coated using an arc ion plating apparatus. Using an alloy target of Al70Cr30 (numerical value is atomic ratio) without providing an interlayer film, the bias voltage of the negative pressure applied to the base material is -100V, nitrogen gas is introduced into the furnace, and the pressure inside the furnace is 3Pa. A coated cutting tool was manufactured by coating about 4 μm of Al and Cr nitrides at an internal temperature of 500 ° C.

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

≪Composition of hard film≫
Cross section of insert for physical property evaluation (SNMN120408) 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. The composition of the hard film was determined from the average of the measured values obtained by measuring arbitrary 5 points at the center of the aluminum nitride hard film in the film thickness direction. The measurement results are shown in Table 3.

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

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

≪Cutting evaluation≫
The coated milling insert was attached to a rotary tool with a replaceable cutting edge (ASRT5063R-4) with a set screw, and the tool life of the hard film was evaluated under the following milling conditions. The flank wear width of the hard film 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 as the tool life. The processing conditions are shown below. The test results are shown in Table 3.
Work material: S55C (30HRC)
Processing method: Milling Insert shape: WDNW140520
Cutting speed: 150 m / min Rotation speed: 758 rpm Feed per blade: 2.05 mm / tooth
Feed rate: 1554 mm / min Axial depth of cut: 1.0 mm
Radial depth of cut: 40 mm
Cutting method: Dry cutting

Examples 1 to 3 and Comparative Example 2 were composed of a set of columnar particles grown in the film thickness direction with respect to the surface of the base material, while Comparative Example 1 was composed of granular particles.
Here, the first embodiment will be described. 9 and 10 are TEM photographs (magnification: 2,000,000 times) of the hard film according to Example 1, respectively, and schematic schematic diagrams thereof. As shown in FIGS. 9 and 10, in the hard film according to Example 1, crystal particles having a portion having a product phase structure and a portion having a single phase structure were confirmed, and the hard film according to the first embodiment consisted of a portion having a laminated structure and a single phase structure. It can be said that it has crystal particles having a portion thereof.

Examples 1 to 3 showed a stable wear mode and a long tool life. On the other hand, in Comparative Examples 1 and 2, the tool life was shortened.
Looking at the X-ray diffraction patterns of Examples 1 to 3 in FIGS. 1 to 3, it was confirmed that in Examples 1 to 3, the peak intensity (count value) on the high angle side after the (311) plane was large. NS. When the value of TB / TA was evaluated, it was confirmed that the value of TB / TA was 0.40 or more in the present implementations 1 to 3 and the peak intensity on the relatively high angle side was relatively large. As a result, it is presumed that Examples 1 to 3 had a large peak intensity on the high angle side and exhibited better durability. FIG. 4 shows the X-ray diffraction pattern of Comparative Example 1, and FIG. 5 shows the X-ray diffraction pattern of Comparative Example 2. In Comparative Examples 1 and 2, it was confirmed that the TB / TA value was 0.2 or less and the peak intensity (count value) on the high angle side was relatively small, and it was presumed that the durability was not sufficient. NS.

1: Chemical vapor deposition equipment (CVD furnace)
2: Chamber 3: Heater 4: Insert installation plate 5: Reaction vessel 5a: Reaction vessel opening 6: Preheating chamber (preheating part)
61: Preheating chamber 62: Cr chloride gas generation chamber 63: Mixing chamber 7: Pipe (gas release part)
83a, 83b, 91a, 91b, 92a, 93a: Nozzle hole (gas outlet)
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 10 : Exhaust pipe 11: Connection path 12: Rotating part during film formation 13a: Gas path of mixed gas B in the preheating chamber 13b: Gas path of mixed gas B in the connection path (longitudinal direction)
13c: Gas path of mixed gas B in the connection path (rotational axis direction)
20: Insert base material 31: Laminated part 32: Single-phase part

Claims (2)

A coated cutting tool that has a hard film on the surface of the base material.
The hard film is a nitride containing 60 atomic% or more of Al and 10 atomic% or more of Cr with respect to the total amount of metal elements including metalloids, and the total content ratio of Al and Cr is 90 atomic% or more. can be,
The hard film is composed of a collection of columnar particles grown in the film thickness direction with respect to the surface of the base material.
The hard film has a (111) plane, a (200) plane, a (220) plane, a (311) plane, a (222) plane, a (400) plane, a (331) plane, and a (420) plane due to the fcc structure. The (422) plane has a peak intensity, and the total peak intensity due to the crystal plane is the TA, (311) plane, (222) plane, (400) plane, (331) plane, (420) plane and (420) plane. 422) A coated cutting tool characterized in that the value of TB / TA is 0.40 or more when the total peak intensity due to the surface is TB. The hard film is a crystal particle having a monophase structure portion having a relatively high Al content ratio and a product phase structure portion having a relatively low Al content ratio in a microstructure using a transmission electron microscope. The coated cutting tool according to claim 1, wherein the particles are dispersed.

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