JP2005226102A - Hard coating, and tool coated with the hard coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hard coating which has improved adhesiveness to a substrate, and excellent oxidation resistance and abrasion resistance, and to provide a tool coated with the hard coating, which copes with dry machining, the speeding up of machining and high feeding in machining. <P>SOLUTION: The hard coating, when phase A is defined as a phase that contains a relatively large amount of Si and/or Mo out of phases selected from a plurality of phases showing the light and shade at a venture, which are observed with a microscope in the matrix of the coating covering a substrate surface, and phase B is defined as a phase that contains a relatively small amount of Si and/or Mo out of the phases, and the amounts of contained Si and/or Mo are determined in the form of an average atomic ratio by a chemical composition analysis, has a difference between the phase A and the phase B of 0.2 to 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

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 coating of the present invention has a plurality of phases showing brightness and darkness when the coating substrate coated on the surface of the substrate is observed with an electron microscope, and is a phase randomly selected from these phases, and Si and / or Mo The phase with a relatively large content is the A phase, the phase with a relatively small Si and / or Mo content is the B phase, and the result of the Si and / or Mo content analysis in the composition analysis is an average value by atomic ratio. The hard film is characterized in that the difference between the A phase and the B phase is 0.2 or more and 5 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 coating of the present invention, the composition of the hard coating is Al _w Ti _x Mo _{y S} iz, where w, x, y, and z are atomic ratios of 20 ≦ w ≦ 50, 25 ≦ x ≦ 75, 2 ≦ y. ≦ 20, 0.01 ≦ z ≦ 10, w + x + y + z = 100, metal component represented by w ≦ x + y + z, and O _a S _b N _100-ab , provided that 0.3 ≦ a ≦ 5, 0.1 ≦ b ≦ 5 and having a composition composed of a non-metallic component and having a coefficient of friction of 0.4 or less. In the vicinity of the surface of the hard coating, Si and oxygen are within a range of 100 eV to 105 eV in ESCA analysis. Is a hard film in which the (200) plane of the hard film and the (100) plane of the substrate have a heteroepitaxial relationship. Further, the hard coating has Ib / Ia when the peak intensity value detected on the (111) plane of the face-centered cubic structure in X-ray diffraction is Ia and the peak intensity value detected on the (200) plane is Ib. ≧ 2.0, and the lattice constant λ (nm) of the (200) plane 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 top surface of the substrate. The hard coating is preferably coated by physical vapor deposition, and the metal components Al, Ti, Mo, and Si are preferably coated with a plurality of evaporation sources having different plasma densities and discharge outputs. 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. High feed processing here is defined as cutting in which the feed amount per blade under the cutting conditions exceeds 0.3 mm / tooth.

  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

  The hard coating of the present invention has a plurality of phases showing brightness and darkness when the coating substrate coated on the surface of the substrate is observed with an electron microscope, and is a phase randomly selected from these phases, and Si and / or Mo A phase with a relatively high content is phase A, and a phase with a relatively low Si and / or Mo content is B phase, and composition analysis, for example, EPMA (Electron Probe Micro analyzer, EPM-1610, manufactured by Shimadzu Corporation) analysis The hard film is characterized in that the result of the Si and / or Mo content analysis in the above is obtained by an average value based on the atomic ratio, and the difference between the A phase and the B phase is 0.2 or more and 5 or less. By making the difference between the average values of the A phase and the B phase within the above specified range, the impact resistance of the hard coating can be improved. The hard coating of the present invention intentionally controls the concentration of Si and / or Mo during film formation to generate a concentration difference, thereby improving impact resistance while maintaining excellent lubrication characteristics, and forming the hard coating itself. It became possible to give high 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 coating of the present invention is formed by arc discharge ion plating (hereinafter referred to as “high density plasma”) using a high-density plasma in order to intentionally generate a Mo and Si concentration difference in the hard coating. AIP)) and a magnetron sputtering method using low density plasma are used. By using this apparatus, it became possible to intentionally control the Si and / or Mo content concentration to generate a concentration difference. 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 magnetron sputtering 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 composition concentration difference in the hard coating. Since the object of the present invention is to maintain the crystal structure of the hard coating in the fcc structure and to impart excellent toughness to the coating, it is preferable to generate a composition concentration difference in the hard coating using the above method. In particular, the composition of the target required for each method is not limited. Magnetron sputtering includes electron beam or closed magnetic field magnetron sputtering, but is not limited to other methods. On the other hand, for the method other than the above, for example, when using the AIP method of high-density plasma, a plurality of evaporation sources are installed in the vacuum apparatus, and alloy targets having different compositions are installed in the respective evaporation sources. It is also conceivable to set different discharge outputs at the respective 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, but the energy generated when ions generated in the plasma are incident on the substrate is large, and the residual compressive stress It is difficult to suppress. In addition, it is difficult to obtain a concentration difference and a hardness difference between the hard coatings of a plurality of phases, and it is difficult to improve the impact resistance characteristics of the hard film and to impart fracture resistance and toughness. Even if the hard film of the present invention is a film having the same composition as compared with the case where the AIP method is used alone, the hardness of the hard film can be increased.

  The hard coating of the present invention is coated by physical vapor deposition, and it is preferable that the metal components Mo and Si and other metal components such as Al and Ti are 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. The invention example 1 in FIG. 2 has a multiphase structure in which a phase coated by high-density plasma AIP and a phase coated by low-density plasma magnetron sputtering are formed, and each phase grows without being continuously divided. I confirmed that As a result of examining the concentration distribution of each element of Mo and Si from the hard coating surface to the inside, it was confirmed that a concentration difference was clearly obtained.

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 additive element effective for welding resistance at high temperatures was found. The composition of the hard coating of the present invention is Al _w Ti _x Mo _{y S} iz, where w, x, y, and z are atomic ratios of 20 ≦ w ≦ 50, 25 ≦ x ≦ 75, 2 ≦ y ≦ 20, 0. 01 ≦ z ≦ 10, w + x + y + z = 100, and w ≦ x + y + z. Here, the numerical value defining range of w is 20 ≦ w ≦ 50. The reason why 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. However, in actual cutting, the more the hard coating Al, This is because an Fe component or the like in the work material induces inward diffusion in the film. Therefore, the w value is 50 or less, and w ≦ x + y + z. On the other hand, when the w value is less than 20, the effect of addition of Al cannot be obtained, and the wear resistance and oxidation resistance of the film are inferior, which is inconvenient. The addition of Mo and Si to the (TiAl) N-based hard coating is effective for preventing the welding phenomenon of the work material. By adding an appropriate amount of Si to the film, it is possible to suppress the movement of Al that causes the welding phenomenon and to improve the peel resistance of the chemically stable Al ₂ O ₃ layer. Further, by adding an appropriate amount of Mo, the Ti oxide can be made dense and fine. As a result, the welding phenomenon is excellent even in a high-temperature environment during cutting, and the heat resistance can be improved. The effectiveness of adding Si to the hard coating of the present invention is that, for example, when applied to a cutting tool, a dense oxide of Si is formed earlier than the oxide of Al near the coating surface due to heat generated during cutting. Thus, it is possible to suppress the inward diffusion of Fe contained in the work material into the hard film and, as a result, to suppress the occurrence of welding. There is an optimum value for the amount of Si added, and z is 0.01 ≦ z ≦ 10. When the z value exceeds 10 and the film hardness and heat resistance tend to be improved, the fracture surface structure of the hard film changes from a columnar structure to a fine granular structure. A fine grain structure is disadvantageous because the crystal grain boundaries of the hard coating increase, and when the cutting heat rises, the routes in which oxygen in the atmosphere and Fe of the work material diffuse inwardly increase. This is because welding occurs on the cutting edge and the lubricity is impaired. Therefore, optimization of the fractured surface structure of the hard coating is one of the important requirements. Particularly in high feed processing, a technique for maintaining the columnar structure regardless of the hard coating material is important. Furthermore, if the z value exceeds 10 and the residual stress inside the film increases. In this case, peeling from the interface between the substrate and the hard coating is likely to occur, and peeling easily occurs particularly in cutting with strong impact resistance. This is inconvenient because welding occurs around the peeled portion. On the other hand, the reason why the z value is 0.01 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.

The effectiveness of Mo added to the (TiAl) N-based hard coating of the present invention is based on Si, which is necessary for improving heat resistance, and a dense crystal of Ti oxide formed immediately below the surface layer when the hard coating is oxidized. It is to make an organization. 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. There is an optimum value for the amount of Mo added, and y is 2 ≦ y ≦ 20. The addition of Mo is effective for increasing the hardness of the hard film in addition to the effect of suppressing the welding due to the heat resistance stability. However, if the y value exceeds 20, the hardness of the hard film decreases. In addition, when coated by physical vapor deposition, the fracture surface structure of the film changes from a columnar structure with excellent impact resistance properties to a fine granular structure, and chipping and scraping wear occurs at the beginning of cutting, so there is no additive effect. It is. 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. On the other hand, when the z value is less than 2, there is no effect of increasing the hardness of the hard coating, and improvement in tool performance cannot be expected. The addition of Mo substantially replaces Ti or Al.

The effectiveness of adding S and O elements to the (TiAl) N-based hard coating of the present invention is to improve lubricity. There are optimum values for the amounts of S and O added, the a value is 0.3 ≦ a ≦ 5, and the b value is 0.1 ≦ a ≦ 5. FIG. 3 shows the results of measuring the friction coefficient when S and O are added to the hard coating. Invention Example 8 is the addition of S with an atomic ratio of b value of 1, and Invention Example 5 is the addition of S with b value of 1 and addition of O with a value of 4.8. Compared with the case of no addition of S and O in Comparative Example 31, Invention Examples 5 and 8 showed a tendency for the friction coefficient to decrease. In high-efficiency machining, by setting the a value to 0.3 or more, welding of the workpiece to the hard film was suppressed, and lubricity was 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 a value is about 0.1. Based on this phenomenon, it was confirmed that the addition of 0.3 or more O reduced the friction coefficient even under high temperature conditions corresponding to cutting. However, the addition of O may have an adverse effect depending on the amount added. When the a value exceeds 5 and the lubrication characteristics are excellent, 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 a value is defined as 0.3 ≦ a ≦ 5. On the other hand, it was confirmed that when S was added, the lubricity was improved by setting the b value to be 0.1 or more, and the friction coefficient was lowered even under high temperature conditions corresponding to cutting. Attempts to add S to a (TiAlMo) N-based hard film, the friction coefficient was 0.8 from the conventional example 30 to 0.3 to 0.4 as shown in the present invention examples 1 to 15. It was confirmed that it could be reduced. This includes a synergistic effect due to the addition of O. When the b value exceeds 5 and the lubrication characteristics are excellent, there is a disadvantage that the hardness of the hard coating is lowered. Therefore, in the present invention, the b value is defined as 0.1 ≦ b ≦ 5. In the case of using a physical vapor deposition apparatus, for example, in addition to the addition method from a MoS ₂ target, the introduction of S with a gas having a vacuum pipe and an environmental treatment facility arranged therein 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 technique to add from a MoS ₂ target using a magnetron sputtering method. The present invention is a technique for imparting excellent toughness to a hard film, and causes simultaneous discharge with a magnetron sputtering system while maintaining strong adhesion by an arc discharge system. Even when a MoS ₂ target is used for the magnetron sputtering method, since the present invention causes simultaneous discharge with the arc electric method having high energy, the S component is dissolved in the TiAlMoSi compound phase. Exists. Therefore, the ratio of the MoS ₂ phase existing in the coating is small, and the area ratio is 3% or less. The hard coating of the present invention can maintain the lubricating performance for a long time by having the hard coating containing Ti, Al, Si and / or Mo having the S-containing compound having the lubricating performance. If the friction coefficient of the film is larger than 0.4, the effect of improving the lubrication characteristics is not seen.

  The total film thickness of the hard coating of the present invention has an average layer thickness of 0.5 to 10 μm, is in the vicinity of the interface between the hard coating and the substrate, and corresponds to 1 to 30% of the average layer thickness from the interface The oxygen content M contained in the hard film over the entire area, and in the vicinity of the surface of the hard film, the oxygen content contained in a region extending from the surface side to a depth corresponding to 1 to 30% of the average layer thickness It is preferable that N−M ≧ 0.3, where N is N and the difference between the two is N−M. Since the residual compressive stress increases due to the addition of O, which affects the adhesion of the film, it is advisable to give considerable consideration to the method of adding O during film formation. As a device for maintaining the adhesion of the film, it is appropriate to gradually increase the O addition amount from the start to the end of film formation. As a result, NM ≧ 0.3, and it becomes possible to obtain a hard film having excellent lubricity and impact resistance. In the hard film of the present invention, the addition of O increases the amount of O added in the hard film near the surface of the film, so that the metal element oxide of the hard film is easily formed. Accordingly, the lubrication characteristics can be improved. On the other hand, it is not preferable to add a large amount of O element from the initial stage of film formation, for example, by physical vapor deposition, because the substrate surface and the inner wall of the processing apparatus are insulated. The ratio B / A> 1.0 of the total amount B (O + N + S) of the nonmetallic elements to the total amount A (Al + Ti + Mo + Si) of the metal elements 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 near the surface of the hard film. FIG. 4 shows the result of analyzing the chemical bonding state by ESCA analysis in the vicinity of the surface of the hard coating of Example 1 of the present invention. 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 film directly above the base must be controlled so that there is a heteroepitaxial relationship at the interface between the base and the hard film. By having a heteroepitaxial relationship, the intermolecular force between the hard coating and the substrate interface can be increased. As shown in FIG. 5, when the (100) plane of WC contained in the substrate and the (200) plane of the (TiAlMoSi) (OSN) hard film are aligned when electron beam diffraction is performed, the intermolecular force is reduced. And can improve adhesion. 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 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 detected intensity of the (111) plane in the X-ray diffraction of the hard film is Ia and the detected intensity of the (200) plane is Ib, if Ib / Ia is less than 2, a large strain is applied to the interface between the substrate and the hard film. Since the crystal grows as it is, 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 optimal (200) plane λ 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 them, 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 was confirmed that it can be adjusted by controlling the Al content on the constituent elements of the present invention and is stable in terms of productivity. . λ decreases under the influence of the atomic radius of the element when Al is increased or Si is added. On the other hand, when Al is added or when film forming conditions are set such that the plasma density is increased during coating, 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 film destruction 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, but the present invention is not limited thereto.

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 magnetron sputtering were provided in a small vacuum apparatus. Various evaporation targets were used as the evaporation source, and the reaction gas was selected from N ₂ gas, CH ₄ gas, and Ar / O ₂ mixed gas to obtain a desired film. As the coating conditions, a substrate temperature of 400 ° C. and a bias voltage of −40V to −150V were applied. Using the obtained hard coating-coated insert, a cutting test was performed under the following cutting conditions 1 and 2. In the evaluation method, processing was performed until the tool became uncut due to chipping or wear of the blade edge, and the cutting length at that time was defined as the tool life. Tables 1 to 3 show the details of the hard coating and the results of the cutting test for the inventive examples, comparative examples, and conventional examples.

(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 (Cutting condition 2)
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)
Cutting depth: 2.0mm
Cutting speed: 120 m / min
1-blade feed amount: 1.0 mm / blade Cutting oil: none Table 1 shows the cutting evaluation results under cutting condition 1 for the chipping resistance of the insert in the cutting process. The work material used in the cutting condition 1 was a material whose holes were previously drilled at equal intervals by a drill. By cutting the surface of the work material under high-efficiency machining conditions, intermittent cutting was assumed, and the possible cutting length until the insert was impacted and damaged was evaluated.

  In each of Invention Examples 1 to 15, evaporation sources having different plasma densities were used in combination. 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 the AIP and magnetron sputtering methods with different plasma densities are used at the time of coating, and the high-hardness film and the low-hardness film are alternately and continuously coated to maintain the wear resistance and lubricity of the hard film. As a result, the film strength could be improved. As a method for forming different phases in the hard film and differentiating the Si content, a method of intermittently and continuously changing the target composition and coating conditions can be considered. The use of evaporation sources with different plasma densities provided better fracture resistance. Comparative Examples 16, 23, and 25 are cases where coating was performed using a single evaporation source so as not to cause a compositional difference. Comparative Example 16 was a coating by magnetron sputtering, but the plasma density could not be increased compared to AIP, so that the coating could not be increased in hardness. 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. On the other hand, Comparative Examples 17, 18, 20 to 22 are cases in which AIP is used and the hard film is coated so that a compositional difference occurs. Although there was a difference in composition, the target cutting performance was not obtained. Particularly, in Comparative Examples 18, 21, and 22, the amount of S added exceeded 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 compositional difference is generated in the film, the residual stress is increased, which adversely affects fracture resistance and adhesion. Some of the comparative examples had a coating hardness exceeding 3500 in Hv, but due to the low toughness of the coating, defects occurred under intermittent cutting conditions, and the tool had a short life. In Comparative Examples 26 and 27, a composition difference was generated in the hard coating by using AIP and magnetron sputtering in combination. However, since the compositional difference exceeded the target range, the fractured surface structure of the hard coating did not show a continuous columnar form, and phases with different compositions were intermittently growing. 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 were improved in chipping resistance by using methods having different plasma densities. As described above, when AIP and magnetron sputtering are used together during coating, when different plasma density methods are used together, the Si composition difference of the hard coating can be controlled, and the insert coated with the hard coating is excellent. It was possible to exhibit the fracture resistance.

  Table 2 shows the test results when the hard coating of the present invention is coated on a cemented carbide insert and mounted on a tool to perform high-efficiency machining under cutting condition 2. Inventive Examples 1-15, Comparative Examples 31-40, and Conventional Examples 28-30, 41 were described in Table 2 and the evaluation results were compared. In the evaluation, when no damage such as sudden defect, abnormal wear, or peeling was observed, the tool life was defined as the point at which the maximum flank wear amount reached 0.3 mm. As shown in Table 2, Examples 1 to 15 of the present invention show that the friction coefficient with respect to steel is 0.4 or less, the hardness of the hard coating is improved, the wear resistance is improved, and the cutting properties are excellent. 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 exhibit low friction coefficient and excellent lubricity, and also reduce the phenomenon of welding of the workpiece to the cutting edge at the initial stage of cutting, as seen in the cutting evaluation results of Comparative Examples 31 to 40. It was observed that almost no wear occurred at the cutting distances that were obtained. This confirmed the effect of the present invention. 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 addition of O, the presence or absence of surface oxides, and the presence or absence of heteroepitaxiality. Furthermore, the balance of the addition amounts of Mo and Si is also important. In this test, those with excellent cutting characteristics on average and those with the highest tool life showed a tendency of Mo> Si. Even when the Si addition amount of the present invention example was larger than the Mo addition amount 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, considering cutting performance, a hard coating of Mo> Si is desirable. The lubricating properties of the hard coating of the present invention were greatly improved by the addition of O. For example, Comparative Example 31 is a case where O is not added, and the cutting performance is almost the same as the conventional example. As in Comparative Examples 33 and 34, even if the metal component is within the range of the present invention, if the a value of the O addition amount exceeds 5, lubrication characteristics are recognized, but early wear occurs due to dynamic cutting. This is presumably because the fracture surface texture form of the hard coating changed from a columnar shape to a fine textured state by adding a large amount of O, and the hardness was lowered without obtaining a high hardness. In Comparative Example 33, since the adhesiveness was taken into account, the initial life was not generated and the wear life was reached. However, in Comparative Example 34, the adhesiveness was not taken into account, so that the hard coating on the insert rake face was peeled off. Appeared prominently. Even if the coating is performed within the range of the hard coating composition of the present invention, if adhesion is not considered, peeling occurs under the current cutting conditions, and stable processing cannot be performed. Comparative Example 36 is a case where the Al component is outside the specified range and adhesion is not taken into consideration. Comparative Example 40 is a case where the Mo component is outside the specified range. When the metal component of the hard coating is out of the specified range, the fracture surface structure becomes finer. When cutting is performed in this state, wear on the insert rake face is rapidly generated, resulting in a short life.

It became clear that the cutting performance was also affected by the O addition method. In Comparative Examples 32, 35, and 38, a predetermined amount of O is added from the start of film formation and is added uniformly without changing the amount until the end of coating. On the other hand, the inventive examples and comparative examples 33, 34, 36, 37, 39, and 40 were added in an inclined manner so that the O addition amount showed a gradient from the substrate and hard coating interface toward the surface from the start to the end of coating. It is a thing. As a result of the cutting test, it was found that a coating in which the addition of O is inclined so as to show a gradient is desirable. In Comparative Examples 37, 39, and 40, it was found that when the addition amounts of Mo and Si are outside the specified ranges, the residual compressive stress is increased, and film peeling at the initial stage of cutting occurs. From the above test results, the improvement effect of the hard film of the present invention is the first effect by setting the composition range of the metal component, the second addition effect of O and S, and the third oxidation of dense Si on the hard film surface. It was obtained by the effect of forming the product, and it was confirmed that the lubrication characteristics were greatly improved and the life could be improved.
Table 3 shows the results of analysis of hard coatings by X-ray diffraction, the detected peak intensity ratio Ib / Ia of the (111) plane and the (200) plane, the lattice constant λ of the (200) plane, and cutting under cutting condition 2 An evaluation result is shown. From Table 3, Comparative Examples 16 to 25 and 42 to 46 were also added with S and O, but because the crystal orientation in X-ray diffraction was out of the specified range, crater wear and peeling occurred easily. Further, it was confirmed that the adjustment of λ is also necessary. In the case of a hard coating such that (200) plane λ exceeds 0.4230 nm as in Comparative Examples 17, 21-24, 42-46, regardless of the metal component composition of the hard coating and the amount of addition of S and O, The cutting life was reached early. 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 stable cutting performance as in the present invention, in addition to the provision of the metal component, S, O addition amount, O addition technique, by controlling the crystal orientation appropriately, the adhesion It is also important to form a film with good properties.

  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, so that the friction characteristics of the hard coating were stabilized and the variation in cutting life of the cutting tool was reduced.

FIG. 1 shows a schematic view of a hard film coating apparatus. FIG. 2 shows the result of observing the 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.

Explanation of symbols

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

Claims (6)

When the film substrate coated on the substrate surface is observed with an electron microscope, there are a plurality of phases showing light and darkness, which are randomly selected from these phases, and have a relatively large Si and / or Mo content. The phase is the A phase, the phase having a relatively small Si and / or Mo content is the B phase, and the Si and / or Mo content analysis result in the composition analysis is obtained as an average value based on the atomic ratio. The hard film is characterized by having a difference of 0.2 or more and 5 or less. 2. The hard film according to claim 1, wherein the composition of the hard film is Al _w Ti _x Mo _{y S} iz, where w, x, y, and z are atomic ratios of 20 ≦ w ≦ 50, 25 ≦ x ≦ 75, 2 ≦ y ≦ 20,0.01 and ≦ z ≦ 10, w + x + y + z = 100, w ≦ x + y + z represented by the metal _{component, O a S b N 100-} a-b, where, 0.3 ≦ a ≦ 5,0 0.1 ≦ b ≦ 5, and has a friction coefficient of 0.4 or less, and in the vicinity of the surface of the hard coating, Si within a range of 100 eV to 105 eV in ESCA analysis. A hard film characterized in that the (200) plane of the hard film has a heteroepitaxial relationship with the (100) plane of the substrate. 3. The hard film according to claim 1, wherein the hard film has a peak intensity value detected on the (111) plane of the face-centered cubic structure in X-ray diffraction as Ia and a peak intensity value detected on the (200) plane. A hard coating film characterized by Ib / Ia ≧ 2.0 and a lattice constant λ (nm) of (200) plane in the range of 0.4155 ≦ λ ≦ 0.4220 when Ib is set. 4. The hard film according to claim 1, wherein at least one intermediate layer selected from Ti nitride, carbonitride, boronitride, TiAl alloy, Cr metal, and W metal is formed on the upper surface of the substrate. Hard film characterized by providing 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.