JP4453902B2 - Hard coating and hard coating tool - Google Patents

Description

  The present invention relates to a hard coating excellent in wear resistance, adhesion, and high temperature oxidation resistance coated on cemented carbide, high speed steel, die steel and the like. The present invention also relates to a hard film coated tool formed of the hard film.

  With a tool coated with a conventional hard coating, the cutting speed is increased for the purpose of improving the efficiency of metal processing, and the high feed cutting process in which the feed amount per blade exceeds 0.3 mm under cutting conditions. However, satisfactory performance has not been obtained in terms of adhesion and mechanical properties of the hard film, such as oxidation resistance and wear resistance. From such a background, a technique for the purpose of further improving the oxidation resistance and wear resistance of a hard coating has been disclosed. Patent Documents 1 and 2 disclose a technique for forming a concentration distribution in a hard film and a technique for improving wear resistance by forming a film having a repeated layer of composition change in which the composition continuously changes. ing. However, both are attempts using only the arc discharge ion plating method in the physical vapor deposition method. Patent Document 3 discloses a technique of coating molybdenum disulfide for the purpose of obtaining lubricity on a machining tool. Patent Document 4 discloses an example of a film in which molybdenum disulfide and TiN are combined. However, the adhesion and hardness of the coating are not sufficient, and there remains a problem in the wear resistance of the cutting tool.

JP 2003-225807 A Japanese Patent No. 3460288 JP-A-5-239618 Japanese National Patent Publication No. 11-509580

  An object of the present invention is to provide a hard film having improved adhesion to a substrate and excellent in oxidation resistance and wear resistance. Another object of the present invention is to improve adhesion to the substrate, have excellent oxidation resistance and wear resistance, and further suppress welding at high temperatures and diffusion of work material elements into the hard coating. It is to provide a tool coated with a hard coating corresponding to dry machining, high speed, and high feed of cutting.

The hard film of the present invention is a hard film in which the surface of a substrate is coated with at least a nitride or oxysulfide of Al, Ti, Mo, and Si. The Al, Ti, Mo, and Si are (Al _w Ti _x Mo _y Si _z ), where w, x, y, and z are atomic% relative to the total amount of Al, Ti, Mo, and Si, and 20 ≦ w ≦ 50, 25 ≦ x ≦ 75, 2 ≦ y ≦ 20 , 0.01 ≦ z ≦ 10, w + x + y + z = 100, w ≦ x + y + z, nitride sulfide or nitric _{sulfide, (O α S β N 100} -α-β), however, oxygen, total sulfur and nitrogen Atomic% with respect to the quantity , represented by 0 ≦ α ≦ 5, 0.1 ≦ β ≦ 5, and when the substrate of the hard film is observed with an electron microscope, a phase coated with high-density plasma and a low density There are a plurality of phases coated with plasma, and the high-density plasma The Si amount z of the phase coated with the low density plasma and the phase coated with the low-density plasma is obtained as an average value, a phase having a relatively large average value of the Si amount z is A phase, and a relatively small phase is B phase. And the difference in Si amount z between the A phase and the B phase is 0.2 atomic% or more and 5 atomic% or less. By adopting the above configuration, it is possible to improve the adhesion of the hard film and provide a hard film having excellent oxidation resistance and wear resistance.

In the hard film of the present invention, the friction coefficient of the hard coating is not less than 0.4, has a binding energy of Si and oxygen in the range of 105eV from 100eV at ESCA analysis of the hard coating, the hard coating X The (200) plane of the face-centered cubic structure in line diffraction and the (100) plane of the cemented carbide of the substrate have a heteroepitaxial relationship. Further, when the peak intensity value of the (111) plane of the face-centered cubic structure is Ia and the peak intensity value of the (200) plane is Ib, the peak intensity ratio Ib / Ia ≧ 2.0, ) Plane lattice constant λ (nm) is in the range of 0.4155 ≦ λ ≦ 0.4220. Further, at least one intermediate layer selected from Ti nitride, carbonitride, boronitride, TiAl alloy, Cr metal, and W metal is provided on the upper surface of the substrate. It is preferable that the convex portions on the surface of the hard film are smoothed by mechanical treatment after the hard film is coated. When the hard film of the present invention is coated on the surface of a wear-resistant member or heat-resistant member that requires high hardness such as a cutting tool, the adhesion of the hard film is improved, and the oxidation resistance and wear resistance are remarkably improved. In particular, it is possible to suppress welding resistance at a high temperature of cutting and diffusion of the work material element into the hard film. Furthermore, it is possible to provide a hard film coated tool that can cope with dry cutting, high speed, and high feed of cutting.

  The hard film of the present invention improves the adhesion between the hard film and the substrate, and has excellent oxidation resistance, wear resistance, lubricity, and fracture resistance. By applying the hard coating of the present invention to cutting tools etc., stability and long tool life can be obtained even in intermittent cutting conditions during die machining, including dry high-efficiency cutting, and productivity in cutting It is extremely effective in improving

When the base of the hard coating is observed with an electron microscope, the hard coating of the present invention has a plurality of phases of a phase coated with high-density plasma and a phase coated with low-density plasma. The Si amount z of the phase coated with the low density plasma and the phase coated with the low density plasma is obtained as an average value. The phase in which the average value of the Si amount z is relatively large is the A phase, the relatively small phase is the B phase, and the difference in the Si amount z between the A phase and the B phase is 0.2 atomic% or more. It is a hard film characterized by being 5 atomic% or less. By making the difference between the average values of the Si amounts z of the A phase and the B phase within the above specified range, the impact resistance of the hard coating can be improved. Hard film of the present invention, by generating a difference intentionally controlling the amount of Si z Si content z during deposition, to improve the impact resistance while maintaining excellent lubricating properties, high hard coating itself It became possible to give toughness. Furthermore, since the low hardness and high hardness films were alternately formed alternately, it was confirmed that not only the impact resistance was improved but also the residual compressive stress that had an effect on the adhesion was suppressed.

As shown in FIG. 1, the hard film of the present invention is formed by providing a phase coated with a high density plasma and a phase coated with the low density plasma on the hard film, and intentionally determining the difference in Si amount z. In order to generate this, an apparatus equipped with an arc discharge ion plating (hereinafter referred to as AIP) method using high-density plasma and a magnetron sputtering (hereinafter referred to as MS) method using low-density plasma is provided. Used. By using the present apparatus, intentionally controlling the difference in Si content z, it becomes possible to generate a difference in Si content z. As employed in the present invention, evaporation sources of different types of generated plasma density are installed in the same vacuum apparatus, and coating is performed by generating discharges at the respective evaporation sources during coating. The combined system of AIP and MS employed in the present invention is intentionally selected in order to improve the impact resistance characteristics of the hard coating and to further generate a difference in Si amount z in the hard coating. In order that the hard film of the present invention maintains the crystal structure in a face-centered cubic structure and imparts excellent toughness to the film, it is preferable to generate a difference in Si amount z in the hard film using the above method. In particular, the composition of the target required for each method is not limited. MS includes electron beam type or closed magnetic field type MS, but is not limited to other types. For example, in a method other than the above, when a high-density plasma AIP method is used, a plurality of evaporation sources are installed in a vacuum apparatus, and an alloy target having a different composition is installed in each evaporation source. It is also conceivable to set different discharge outputs at the evaporation sources. However, in the coating by the AIP method, the plasma density generated at the time of coating is very high, so that a good quality film is formed. It is difficult to suppress. In other words, it is difficult to produce a difference in the Si amount z and hardness of the hard coating for each phase only with the phase coated with high-density plasma, improving the impact resistance properties of the hard coating, and providing fracture resistance and toughness. It is difficult to do.

The hard coating of the present invention is preferably coated by physical vapor deposition using high-density plasma or low-density plasma, and the metal components Mo, Si, Al, and Ti are preferably coated by a plurality of evaporation sources having different discharge outputs. The hard coating method of the present invention is preferably a physical vapor deposition method in which a bias voltage is applied to the coated substrate side. When considering the thermal effects on the coated substrate, coating adhesion, etc., and considering the fatigue strength when the coated substrate is used as a cutting tool, the compressive stress generated in the coated coating can be coated at a relatively low temperature. The processing by the film forming apparatus provided with a plurality of evaporation sources having different plasma densities, such as AIP and sputter controllable, exhibits the most stable cutting performance. If necessary, an apparatus using a plasma-assisted chemical vapor deposition apparatus and a physical vapor deposition method together may be used.
FIG. 2 shows the result of observing the film cross section of Example 1 of the present invention. In Example 1 of the present invention shown in FIG. 2, the phase coated with high-density plasma AIP and the phase coated with low-density plasma MS have a multiphase structure, and each phase grows without being continuously divided. Confirmed that.

When the hard coating of the present invention is used with a cutting tool as a coated substrate, this hard coating coated tool can improve adhesion and wear resistance by preventing the welding phenomenon of the work material. That is, the phenomenon of occurrence of welding in the cutting process was considered, and the effect of welding resistance of various elements constituting the hard film was examined from this, and an element effective for welding resistance at high temperatures was found.
Al, Ti, Mo and Si of the hard coating of the present invention are (Al _w Ti _x Mo _y Si _z ), where w, x, y and z are atoms with respect to the total amount of the Al, Ti, Mo and Si. %, 20 ≦ w ≦ 50, 25 ≦ x ≦ 75, 2 ≦ y ≦ 20, 0.01 ≦ z ≦ 10, w + x + y + z = 100, w ≦ x + y + z.
The numerical value range of the Al amount w is 20 ≦ w ≦ 50. The reason for w ≦ 50 is that when w increases in the metal composition balance, Al ₂ O ₃ is formed on the surface layer and the static heat resistance is excellent, but in actual cutting, the Al amount w of the hard coating is large. This is because the Fe component in the work material induces inward diffusion in the film. Therefore, the Al amount w is 50 atomic% or less, and w ≦ x + y + z. If the Al amount w is less than 20 atomic%, the effect of Al cannot be obtained, and the wear resistance and oxidation resistance of the film are inferior, which is inconvenient.
The amount of Si z is 0.01 ≦ z ≦ 10. When the Si amount z exceeds 10 atomic%, the film hardness and heat resistance tend to be improved, but the fracture surface structure of the hard film changes from a columnar structure to a fine granular structure. When it becomes a fine grain structure, the crystal grain boundary of the hard coating increases, and when the cutting heat rises, it increases the path through which oxygen in the atmosphere and Fe of the work material diffuse inward, which is inconvenient and has a cutting edge. Welding occurs and lubricity is impaired. Next, the residual stress inside the film increases, and peeling from the interface between the substrate and the hard film is likely to occur, and peeling easily occurs particularly in cutting processing with high impact resistance. This is inconvenient because welding occurs around the peeled portion. The reason why the Si amount z is 0.01 atomic% or more is that it is an easy detection point in Si analysis. In consideration of stability during mass production, it is necessary to perform analysis in a short time in order to perform mass production without delay.

Mo amount y is 2 ≦ y ≦ 20. The Mo amount y is to make the Ti oxide immediately below the surface layer formed when the hard coating is oxidized into a dense crystal structure based on the Si amount z necessary for improving heat resistance. This oxide layer having a dense crystal structure has an effect of suppressing the intrusion of oxygen that diffuses inwardly through Si and Al oxides formed in the vicinity of the surface layer. Thereby, densification of the crystal structure of the Ti oxide can suppress peeling of the surface Al ₂ O ₃ layer. The Mo amount y is effective for increasing the hardness of the hard coating, in addition to the effect of suppressing welding due to heat resistance stability. However, if the Mo amount y exceeds 20 atomic%, the hardness of the hard coating decreases. In addition, when coated by physical vapor deposition, the fracture surface structure of the film changes from a columnar structure having excellent impact resistance characteristics to a fine granular structure, and chipping and scraping wear occur at the beginning of cutting. Further, the discharge of the vapor deposition source becomes unstable when the hard film is coated, and it becomes difficult to form a uniform and stable film. This is because Mo is a refractory metal. When the Mo amount y is less than 2 atomic%, there is no effect of increasing the hardness of the hard coating, and improvement in tool performance cannot be expected.

窒硫product or nitric sulfide of the hard coating of the present invention _{(O α S β N 100-} α-β), however, oxygen in atomic% to the total amount of sulfur and nitrogen, 0 ≦ α ≦ 5,0. The effectiveness of 1 ≦ β ≦ 5 is to improve lubricity.
FIG. 3 shows the results of measuring the friction coefficient when oxygen or sulfur is contained in the hard coating. Invention Example 8 has a sulfur content β = 1 atomic%, and Invention Example 5 has a sulfur content β = 1 atomic% and an oxygen content α = 4.8 atomic%. Compared to the case of Comparative Example 31 where oxygen and sulfur were absent, Invention Examples 5 and 8 showed a tendency for the friction coefficient to decrease. During high-efficiency processing, the amount of oxygen α is set to 0.3 atomic% or more, so that welding of the workpiece to the hard film is suppressed and lubricity is improved. In the physical vapor deposition method, when the amount of oxygen in the hard film is analyzed from the influence of residual oxygen remaining in the vacuum apparatus at the time of coating, it is detected that the amount of oxygen α is about 0.1 atomic%. Based on this phenomenon, it was confirmed that the coefficient of friction was lowered even under high temperature conditions corresponding to cutting when the oxygen content was α = 0.3 atomic% or more. However, the oxygen amount α may have an adverse effect. When the oxygen amount α exceeds 5 atomic%, the lubrication characteristics are excellent, but the hardness of the hard coating decreases. Moreover, the crystal structure form of the hard coating cross-section becomes finer, and there arises a problem that scuffing wear is likely to occur. Therefore, in the present invention, the oxygen amount α is defined as 0 ≦ α ≦ 5, 0.
It was confirmed that by setting the sulfur amount β to 0.1% or more, the lubricity was improved and the friction coefficient was lowered even under high temperature conditions corresponding to cutting. When (TiAlMo) N-based hard coating was attempted to be sulfur, the friction coefficient was reduced from 0.3 to 0.4 as shown in Examples 1 to 15 of the present invention from 0.8 in Conventional Example 30. I confirmed that I can do it. This includes a synergistic effect due to the amount of oxygen. When the amount of sulfur β exceeds 5%, the lubrication characteristics are excellent, but the inconvenience that the hardness of the hard coating is lowered occurs. Therefore, in the present invention, the sulfur amount β is defined as 0.1 ≦ βb ≦ 5. As a method for adding sulfur, when a physical vapor deposition apparatus is used, for example, in addition to a method for adding from a MoS ₂ target, introduction with a gas in which vacuum piping and environmental treatment equipment are arranged is also conceivable. However, since it is difficult to add from a reactive gas with the current physical vapor deposition technique, it is a simple method to add from a MoS ₂ target using the MS method. The present invention is a technique for imparting excellent toughness to a hard coating, and causes simultaneous discharge with the MS system while maintaining strong adhesion with the arc discharge system. Even when the MoS ₂ target is used in the MS system, the present invention causes simultaneous discharge with the arc electric system having high energy, so the S component is dissolved in the (TiAlMoSi) compound phase. Exist. Accordingly, the ratio of the MoS ₂ phase present in the hard coating is small, and the area ratio is 3% or less.
The hard film of the present invention can maintain the lubricating performance for a long time by having the hard film containing Ti, Al, Si and Mo having an S-containing compound having a lubricating performance. If the coefficient of friction of the hard coating is larger than 0.4, the effect of improving the lubrication characteristics is not seen, so it was set to 0.4 or less.

The total film thickness of the hard film of the present invention is 0.5 to 10 μm in average layer thickness, and the hard film covers the region corresponding to 1 to 30% of the average layer thickness from the interface with the substrate of the hard film. When the amount of oxygen contained is M, the amount of oxygen contained in a region extending from the surface of the hard coating to a depth corresponding to 1 to 30% of the average layer thickness, and the difference between the two is (NM) , (N−M) ≧ 0.3. Since the residual compressive stress increases due to the oxygen amount α, it affects the adhesion of the hard coating, and therefore, it is advisable to give considerable consideration to the method of adding oxygen during film formation. As a device for maintaining the adhesion of the hard film, it is appropriate to gradually increase the oxygen amount from the start to the end of film formation. As a result, (N−M) ≧ 0.3, and it becomes possible to obtain a hard coating having excellent lubricity and impact resistance.
In the hard coating of the present invention, an oxide of a metal element of the hard coating is formed by increasing the amount of oxygen α contained in a region extending from the surface of the hard coating to a depth corresponding to 1 to 30% of the average layer thickness. It is easy to be done. Therefore, the lubrication characteristics can be improved. For example, adding a large amount of oxygen from the initial stage of film formation by physical vapor deposition is not preferable because the surface of the substrate and the inner wall of the processing apparatus are insulated. The ratio of the total amount of nonmetallic elements (O + N + S) to the total amount of metal elements (Al + Ti + Mo + Si) is nonmetallic component / metallic component> 1.0, and is preferably 1.02 or more. The upper limit of this ratio is preferably 1.7.

  The hard film of the present invention has a binding energy of Si and oxygen in the range of 100 eV to 105 eV in ESCA analysis. FIG. 4 shows the result of analyzing the chemical bonding state of the hard coating of Example 1 of the present invention by ESCA analysis. From FIG. 4, it was confirmed that the hard coating of the present invention has a binding energy of Si and oxygen in the range of 100 eV to 105 eV. This is because Si—O is formed preferentially due to the difference in free energy of formation between Al—O and Si—O. The formation of this dense oxide enhances the lubrication characteristics and reduces the workpiece welding phenomenon that occurs during high-efficiency cutting.

The hard coating of the present invention must have strong adhesion to the substrate in order to exhibit performance under the conditions of high feed cutting. For this purpose, the orientation plane of the hard coating directly above the substrate must be controlled so that there is a heteroepitaxial relationship at the interface between the cemented carbide of the substrate and the hard coating. By having a heteroepitaxial relationship, the intermolecular force at the interface between the hard coating and the cemented carbide of the substrate can be increased. As shown in FIG. 5, by aligning the (100) plane of WC contained in the cemented carbide of the substrate with the (200) plane of the hard coating of the present invention when X- ray diffraction is performed, Strength can be increased and adhesion can be improved. Since the hard coating of the present invention has a large residual compressive stress, a heteroepitaxial relationship must be formed at the interface between the cemented carbide of the substrate and the hard coating. Thereby, the feature of the hard film which solved the problem of adhesiveness and improved functionality is exhibited.

The hard coating of the present invention controls the crystal orientation and suppresses the occurrence of strain at the interface between the substrate and the hard coating to a minimum. When the substrate is polycrystalline such as cemented carbide, the (200) plane is oriented to cover the hard film having a face-centered cubic structure on the (100) plane, which is the preferred WC orientation after sintering. You have to control it. When the peak intensity value of the (111) plane in the X-ray diffraction of the hard film is Ia and the peak intensity value of the (200) plane is Ib, if Ib / Ia is less than 2, the interface between the substrate and the hard film is large. Since the crystal grows with strain, the bonding strength becomes insufficient. In addition, the internal stress of the hard coating increases and peels easily. Therefore, in order to ensure adhesion that the hard coating of the present invention can withstand severe cutting conditions, Ib / Ia ≧ 2.0.
In order for the hard coating of the present invention to have stronger adhesion, it is necessary to control the lattice constant λ of the hard coating. λ affects the residual stress value. When the residual stress value increases, it becomes difficult to maintain the adhesion. Therefore, the optimum λ of the (200) plane for maintaining the adhesion was obtained, and 0.4155 ≦ λ ≦ 0.4220 was obtained. When λ is larger than 0.4220 nm, the compressive stress remaining in the hard film exceeds 8 GPa, so that a large stress is applied to the interface between the substrate and the hard film. Even if a heteroepitaxial relationship is established between the two, hard film peeling occurs. When the hard film of the present invention is used with a cutting tool as a coated substrate, the superiority as a cutting tool is impaired. Therefore, λ should not exceed 0.4220 nm. On the other hand, the lower limit of λ is 0.4155 nm. If λ is less than 0.4155 nm, the lubrication characteristics of the hard film will be noticeably deteriorated, which is not preferable. The range in which the excellent characteristics of the hard coating can be sufficiently extracted is 0.4155 ≦ λ ≦ 0.4220. In order to control λ within the specified range and control the residual stress, it is possible to adjust by controlling the Al amount w on the constituent elements of the present invention, and it was confirmed that the production is stable. . λ decreases under the influence of the atomic radius of the element when the Al amount w is increased or when the Si amount z is large. It tends to increase when the Al amount w is suppressed or when film forming conditions are set such that the plasma density increases during coating, and at the same time, the residual compressive stress tends to increase.

In the hard coating of the present invention, it is preferable to provide at least one intermediate layer selected from Ti nitride, carbonitride, boronitride, TiAl alloy, Cr metal, and W metal on the upper surface of the substrate. This intermediate layer exists between the hard coating and the substrate and has the effect of improving the adhesion. When the hard coating of the present invention is used with a cutting tool as a coated substrate, it is assumed that it is used for dry high-efficiency cutting. However, when the usage is wet cutting, it is necessary to further strengthen the adhesion between the substrate and the hard coating interface. This is because, in a wet machining situation, a tool that has become hot due to cutting heat is rapidly cooled by the cutting fluid. In general, it has penetrated as a means to reduce the cutting temperature and improve the tool life, but in high-efficiency machining, the cutting heat is very high, so when quenched with cutting fluid, the difference between expansion and contraction is large. Thus, a very large load is brought to the interface where the hard coating is bonded. Due to the presence of this intermediate layer, it is possible to avoid the occurrence of hard film breakage due to repeated fatigue.
By smoothing the convex portions on the surface of the hard film by mechanical treatment after the hard film is coated, the friction characteristics of the hard film are stabilized, which is preferable. For example, when the hard coating of the present invention is used with a cutting tool as a coated substrate, variation in cutting life can be reduced, and a preferable cutting tool can be obtained.
The present invention relates to a hard coating excellent in wear resistance, adhesion and high temperature oxidation resistance coated on cemented carbide, high speed steel, die steel, etc., and in particular, cutting tools, molds, bearings, dies, rolls, pistons. It is preferable to coat the surface of a heat-resistant member such as a ring or a sliding member, such as a wear-resistant member or internal combustion engine component that requires high hardness. The present invention will be described based on the following examples.

A cemented carbide insert serving as a substrate was coated using a device in which an evaporation source by AIP and an evaporation source by MS were provided in a small vacuum apparatus. As the evaporation source, various alloy targets were used, and as the reaction gas, an N ₂ gas, a CH ₄ gas, and an Ar / O ₂ mixed gas were selected from which a desired hard film was obtained. As the coating conditions, a substrate temperature of 400 ° C. and a bias voltage of −40V to −150V were applied. Table 1 shows the metal component, non-metal component, evaporation source, and evaporation source control parameter of the hard coating.

Using the obtained hard coating-coated insert, a cutting test was performed under cutting conditions 1. Evaluation was performed until the tool became uncuttable due to chipping or wear of the cutting edge, and the cutting length at that time was defined as the tool life. Table 1 also shows the results of the cutting test.
(Cutting condition 1)
Tool: Face mill Insert shape: SDE53 type special shape Cutting method: Center cut method Workpiece shape: width 100mm x length 250mm
Work material: S50C (HRC30), Φ6 drill hole porous surface cutting depth: 2.0mm
Cutting speed: 120 m / min
1-blade feed amount: 1.0 mm / blade Cutting oil: None

From Table 1, Examples 1 to 15 of the present invention used evaporation sources having different plasma densities. On the other hand, Comparative Examples 16 to 27 and Conventional Examples 28 to 30 are cases where a single evaporation source having the same plasma density is used. Inventive Examples 1 to 15 showed superior cutting performance. This is because AIP and MS with different plasma densities are used together during coating, and the phase coated with high-density plasma is coated with high hardness and the phase coated with low-density plasma is alternately coated with low hardness. The strength of the hard coating could be improved while maintaining the wear resistance and lubricity of the hard coating. In order to form a phase with different composition such as a phase coated with a high density plasma on a hard film and a phase coated with a low density plasma, and to provide a difference in Si amount z , the target composition and coating conditions are intermittent. Although a continuous change method is conceivable, the use of evaporation sources having different plasma densities, such as those employed in the present invention, has yielded superior defect resistance characteristics.
Comparative Examples 16, 23, and 25 are cases in which a single evaporation source is used to cover the Si amount z so that no difference occurs. Although the comparative example 16 is coating by MS, since the plasma density cannot be increased as compared with AIP, the hardness of the hard coating could not be increased. Therefore, the wear resistance is not sufficient, leading to initial defects. In Comparative Examples 23 and 25, the hard coating tended to increase in hardness, but the toughness became poor and the intermittent cutting performance could not be improved. Comparative Examples 17, 18, 20 to 22 are cases in which AIP is used and coating is performed so that a difference occurs in the Si amount z of the hard coating. Although a difference in the Si amount z occurred, the target cutting performance was not obtained. In particular, Comparative Examples 18, 21, and 22 had a sulfur content exceeding the appropriate range of the present invention. In the case of coating only with AIP, the hard film tends to have a high hardness because the plasma density generated during discharge is large regardless of the target composition. Accordingly, the toughness is insufficient. As shown in the comparative example, even if a difference in the Si amount z occurs in the hard coating, the residual stress is increased, which adversely affects the fracture resistance and adhesion. Some of the comparative examples had a hard film hardness exceeding 3500 in Hv, but due to the low toughness of the hard film, defects occurred under intermittent cutting conditions, and the tool had a short life. In Comparative Examples 26 and 27, AIP and MS were used in combination to generate a difference in Si amount z in the hard coating. However, since the difference in the Si amount z exceeded the target range, the fracture surface texture form of the hard film did not show a continuous columnar form, and phases with different compositions were intermittently growing continuously. For this reason, the bonding force between the phases was weak, and film breakage occurred, and the target cutting performance could not be obtained. However, it was confirmed that Comparative Examples 26 and 27 improved the fracture resistance. As mentioned above, when AIP and MS are used together during coating, when using different methods of plasma density, the difference in Si amount z of the hard coating can be controlled, and the insert coated with the hard coating is excellent. It was possible to demonstrate the fracture resistance.

Next, a cutting test was performed under cutting conditions 2. In the evaluation of the cutting condition 2, the tool life was determined when the maximum wear amount of the flank reached 0.3 mm when no sudden defect, abnormal wear, or damage form accompanied by peeling was observed. Tables 2 and 3 show the results of the cutting test.
(Cutting condition 2)
Tool: Front milling Insert shape: SDE53 type special shape Cutting method: Center cut method Workpiece shape: width 100mm x length 250mm
Work material: S50C (HRC30)
Cutting depth: 2.0mm
Cutting speed: 120 m / min
1-blade feed amount: 1.0 mm / blade Cutting oil: None

From Tables 2 and 3, Invention Examples 1 to 15 show that the coefficient of friction against steel is 0.4 or less, improve the hardness of the hard coating, improve the wear resistance, and have excellent cutting characteristics. It was. In the present invention, the problems of adhesion, lubricity and wear resistance were improved, and satisfactory results could be obtained by greatly improving the performance. Inventive Examples 3, 7, and 12 showed a long cutting life in this cutting evaluation, and improved cutting life over the conventional Examples 28, 29, and 30. Inventive Examples 3 and 12 exhibited low friction coefficient and excellent lubricity, and also reduced the phenomenon of welding of the workpiece to the cutting edge in the initial stage of cutting. Invention Example 12 was able to obtain 2.4 times longer life than Conventional Examples 29 and 30 that had the longest life among the conventional examples. The correlation between the metal component composition and the cutting life described in the examples of the present invention is also affected by the amount of oxygen, the presence or absence of surface oxides, and the presence or absence of heteroepitaxiality. Furthermore, the balance between the Mo amount y and the Si amount z is also important. In this test, those having excellent cutting characteristics on average and having the highest tool life showed a tendency of Mo amount y> Si amount z. Even if the Si amount z of the present invention example was larger than the Mo amount y within the specified amount range, it was confirmed that sufficient cutting performance was exhibited when compared with the conventional example and the comparative example. However, in consideration of cutting performance, a hard coating of Mo amount y> Si amount z is desirable. The hard coating of the present invention greatly improved the lubrication characteristics depending on the amount of oxygen. For example, Comparative Example 31 was a case where neither oxygen nor sulfur was added, and the cutting performance was almost the same as that of the conventional example.
Although Comparative Examples 16 to 25 were examples in which oxygen and sulfur were contained, crater wear and peeling occurred easily because the crystal orientation in X-ray diffraction was outside the specified range. Further, it was confirmed that the adjustment of λ is also necessary. In the case of a hard coating such that the (200) plane λ exceeds 0.4230 nm as in Comparative Examples 17, 21 to 24, the cutting life is shortened regardless of the metal component composition of the hard coating and the amounts of sulfur and oxygen. Reached. The value of λ affects the internal stress level of the hard coating. When λ is large, even if heteroepitaxial is established at the interface between the substrate and the hard film, the residual compressive stress increases, and the hard film easily breaks or peels off due to the increase in stress at the interface. As a result, the tool life is not stable and the life is shortened. Therefore, in order to improve the cutting performance and show a stable cutting performance as in the present invention, the film is formed with good adhesion by appropriately controlling the crystal orientation in addition to the definition of the metal component, the amount of oxygen and the amount of sulfur. It is also important to do.

  Furthermore, by providing an intermediate layer of Ti nitride, carbonitride, boronitride, TiAl alloy, Cr metal, W metal, etc. directly on the upper surface of the substrate, the adhesion is further reinforced to improve delamination resistance and resistance. The effect of improving defect characteristics was recognized. It was recognized that, after coating the hard coating, the convex portions on the surface of the hard coating were smoothed by mechanical treatment, thereby stabilizing the friction characteristics of the hard coating and reducing the variation in cutting life of the cutting tool.

FIG. 1 shows a schematic view of a hard film coating apparatus. FIG. 2 shows the observation result of the hard film cross section of the example of the present invention. FIG. 3 shows the measurement results of the friction coefficient of the hard coating. FIG. 4 shows the analysis result of the chemical bonding state by ESCA analysis of the hard coating. FIG. 5 shows the heteroepitaxial relationship at the interface between the substrate and the hard coating.

1: Vacuum device 2: AIP evaporation source 3: MS evaporation source 4: Substrate holding jig 5: Direction of rotation

Claims (6)

In a hard film in which the surface of the substrate is coated with at least Al, Ti, Mo and Si oxysulfides or oxysulfides, the Al, Ti, Mo and Si are (Al _w Ti _x Mo _y Si _z ), , W, x, y, and z are atomic% based on the total amount of Al, Ti, Mo, and Si. 20 ≦ w ≦ 50, 25 ≦ x ≦ 75, 2 ≦ y ≦ 20, 0.01 ≦ z ≦ 10, w + x + y + z = 100, w ≦ x + y + z, nitride sulfide or nitric _{sulfide, (O α S β N 100} -α-β), however, oxygen in atomic% to the total amount of sulfur and nitrogen, 0 ≦ α ≦ 5, 0.1 ≦ β ≦ 5, and when the substrate of the hard coating is observed with an electron microscope, a phase coated with high-density plasma and a phase coated with low-density plasma A plurality of phases present, the phase coated with the high density plasma, The Si amount z of the phase coated with the low-density plasma is obtained as an average value, a phase having a relatively large average value of the Si amount z is defined as A phase, and a relatively small phase is defined as B phase. A hard film characterized in that the difference in Si amount z of the phase is 0.2 atomic% or more and 5 atomic% or less. In the hard film of claim 1, wherein the friction coefficient of the hard coating is 0.4 or less, in the ESCA analysis of the hard coating has a bond energy of Si and oxygen from 100eV in the range of 105EV, rigid A hard film characterized in that the (200) plane of the face-centered cubic structure in the X-ray diffraction of the film and the (100) plane of the cemented carbide of the substrate have a heteroepitaxial relationship. The hard film according to claim 1 or 2, wherein the peak intensity ratio Ib / Ia ≧ when the peak intensity value of the (111) plane of the face-centered cubic structure is Ia and the peak intensity value of the (200) plane is Ib. A hard coating film having a lattice constant λ (nm) of the (200) plane in a range of 0.4155 ≦ λ ≦ 0.4220. 4. The hard coating film according to claim 1, wherein at least one intermediate selected from Ti nitride, carbonitride, boronitride, TiAl alloy, Cr metal, and W metal is formed on the upper surface of the substrate. Hard coating characterized by providing a layer. 5. The hard film according to claim 1, wherein the surface of the hard film is smoothed by machining. A hard film-coated tool, which is coated with the hard film according to claim 1.