JP2007169743A - Coated member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated member capable of reducing the residual compressive stress in a boron nitride coating film, and enhancing the wear resistance of the coated member under a service environment requesting the wear resistance. <P>SOLUTION: In the coated member, a compound coating film consisting of boron, nitrogen and oxygen is coated on a surface of a base material. The compound coating film has a tissue structure with amorphous boron nitride being dispersed in crystalline boron nitride. The sectional area of a zone of the amorphous boron nitride in the section of the compound coating film is replaced by the area of a circle, and the diameter of the circle is obtained as the diameter of the equivalent circle. In this case, the diameter is below 10 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a covering member coated with boron nitride.

  Improvement studies for reducing the residual compressive stress of the boron nitride film are proposed in the following Patent Documents 1 to 3.

JP-A-8-11004 JP 2002-167205 A JP 2005-297142 A

  Patent Document 1 shows an example in which cBN, hBN, wBN, amorphous BN, and the like as a boron nitride film are two-layered with a film such as TiN, and the adhesion to the substrate is improved. Patent Document 2 describes the boron nitride film itself. The residual compressive stress is reduced, and Patent Document 3 discloses an example of two layers. An object of the present invention is to provide a covering member capable of reducing the residual compressive stress of the boron nitride film and further improving the wear resistance of the covering member in a use environment where wear resistance is required.

  The present invention is a member having a substrate surface coated with a compound film comprising boron, nitrogen, and oxygen, the compound film having a structure in which amorphous boron nitride is dispersed in crystalline boron nitride, and The covering member is characterized in that the area of the amorphous boron nitride region in the cross section of the compound film is less than 10 nm when calculated as an equivalent circular diameter which is a diameter when the area is replaced by a circle. By adopting the above configuration, the residual compressive stress of the compound film can be reduced without impairing the excellent characteristics of boron nitride, and in the use environment where wear resistance is required, the wear resistance of the covering member can be further reduced. The covering member which can improve property can be provided.

  In the compound film of the present invention, the crystalline boron nitride preferably has a hexagonal and / or cubic crystal structure. Further, when boron in the compound film is present as an oxide, it may be 0.3% or more and less than 10% by mass, or when boron is present as a simple substance, it may be 1% or more and less than 25%. preferable. An A layer is provided between the base material and the compound film, and the A layer is a nitride, oxide or boride of one or more elements selected from the periodic table 4a, 5a, and 6a group elements, Al and Si. , Sulfides, carbides, or a solid solution or a mixture thereof. Furthermore, it is more preferable to laminate | stack a compound membrane | film | coat and A layer alternately in 2 or more layers and less than 5000 layers.

  The covering member of the present invention provides a covering member capable of reducing the residual compressive stress of the boron nitride film and further improving the wear resistance of the covering member in a use environment where wear resistance is required. I was able to. As a result, the improvement in wear resistance of the covering member has become extremely effective for improving productivity and reducing cost.

Boron nitride is promising as a cutting tool for material processing applications such as hardened steel because it is hard and has excellent heat resistance and low reactivity with iron. A film mainly composed of boron nitride, for example, is formed by physical stress (hereinafter referred to as PVD) due to the application of residual stress due to coating conditions such as ion bombardment and thermal distortion with the substrate. Residual stress is generated. In particular, the former residual stress is dominant, and an extremely high residual compressive stress is generated inside the film, and peeling occurs when left after film formation. Moreover, peeling often occurs early after use as an abrasion resistant film. Accordingly, it is an object of the present invention to improve the wear resistance of a covering member coated with boron nitride.
The coated member of the present invention is a member coated with a compound film composed of boron, nitrogen, and oxygen. Therefore, for example, the balance may contain carbon, sodium, calcium, tungsten, etc. inevitably mixed. Further, the compound film has a structure in which amorphous boron nitride is dispersed in crystalline boron nitride. In other words, it is an important improvement of the present invention that the crystalline boron nitride as the matrix phase is composed of a textured structure surrounding the amorphous boron nitride in the dispersed phase. When comprised from these structure | tissue structures, it has the effect of reducing a residual compressive stress, having high hardness. This is because amorphous boron nitride suppresses the progress of the transition and, as a result, relieves the residual compressive stress. With this configuration, it is possible to exhibit the characteristics of boron nitride sufficiently in a wear environment, and at the same time, have excellent peel resistance and improve wear resistance. Here, the state in which the compound film has a structure in which amorphous boron nitride is dispersed in crystalline boron nitride means that the total area of the region occupied by crystalline boron nitride in the cross-sectional structure of the compound film is P, non- When the total area of the region occupied by the crystalline boron nitride is Q, it can be said that P ≧ Q is satisfied. In order to confirm this structure, it is effective to observe the cross section of the film with a transmission electron microscope.
The covering member of the present invention is particularly effective for improving the wear resistance of the covering member when the equivalent circular diameter of the amorphous boron nitride region satisfies less than 10 nm. If the equivalent circular diameter of the region of amorphous boron nitride dispersed in crystalline boron nitride exceeds 10 nm, the residual compressive stress in crystalline boron nitride may not be sufficiently relaxed. Therefore, the peeling resistance tends to be lowered, which is inconvenient.
When the crystalline boron nitride crystal structure in the compound film of the present invention is a hexagonal crystal (hereinafter referred to as hcp) and / or a face-centered cubic crystal (hereinafter referred to as fcc), the wear resistance is particularly improved. It is effective for. When the crystalline structure of crystalline boron nitride is hcp, it is effective for improving lubricity. Further, in the case of fcc, it is effective for wear resistance and the life of the covering member is improved. When hcp and fcc coexist, these intermediate characteristics are exhibited. In particular, when the ratio of hcp to fcc is higher than the crystalline structure of crystalline boron nitride, it is effective for improving the lubricity and wear resistance of the covering member. More specifically, the ratio of crystalline boron nitride in boron nitride is optimum when hcp is 60% or more and 97% or less, and the balance is fcc.
When boron is present in the boron nitride of the compound film of the present invention as an oxide in an amount of 0.3% or more and less than 10%, it is particularly effective in relieving residual compressive stress and improves peeling resistance. Is preferable. On the other hand, when the boron oxide is less than 0.3%, oxygen does not have an effective action for reducing the residual compressive stress. On the other hand, the presence of 10% or more is not preferable because the strength of the compound film tends to decrease. X-ray photoelectron spectroscopy is effective as a method for confirming the bonding state of boron.
It is also effective in reducing the residual compressive stress of the boron nitride layer that boron exists as a simple substance in the boron nitride of the compound film of the present invention in an amount of 1% or more and less than 25%. On the other hand, when the amount of boron alone is less than 1%, it is confirmed that the boron does not effectively reduce the residual compressive stress. On the other hand, the presence of 25% or more is not preferable because the strength of the film tends to decrease.
The covering member of the present invention has an A layer between the base material and the compound film, and the A layer is a nitride of one or more elements selected from periodic table 4a, 5a, 6a group elements, Al, and Si. It is preferable that it is made of any one of oxides, oxides, borides, sulfides and carbides, or a solid solution or a mixture thereof. A layer can improve the adhesiveness of a base material and a compound membrane | film | coat, and can supplement the characteristic of a compound membrane | film | coat. For example, by adopting a layer having excellent heat resistance as the A layer, film characteristics satisfying both the heat resistance and the characteristics of the compound film of the present invention can be obtained. In addition, the A layer is not necessarily one layer selected from the above elements, and a plurality of layers having different compositions can be laminated, and wear resistance can be improved. Particularly preferable examples of the A layer include (AlTi) N, (AlTiSi) N, (TiSi) N, (AlCr) N, and (AlCrSi) N. Furthermore, it is also preferable to laminate the compound film and the A layer alternately in the range of 2 or more and less than 5000 layers from the viewpoint of improving wear resistance and peel resistance. As the layer thickness of each layer, the stacking effect is confirmed in the range of 2 nm or more and less than 2 μm. Exceeding 5000 layers is inconvenient because the peel resistance tends to decrease.

  Examples of the base material of the covering member of the present invention include cemented carbide, cermet, high-speed steel, ceramics, and the like, and any of them is preferable because the effects of the present invention can be confirmed. The covering member is preferably a cutting tool, and the effect of improving wear resistance can be remarkably confirmed. Examples of the cutting tool include an end mill, a drill, a blade exchangeable tool, a reamer, a router, and a small-diameter drill for a printed circuit board. This is particularly effective for a small-diameter rotating tool having a tool blade diameter of less than 1 mm. The means for coating the coating of the present invention is not particularly limited, but PVD methods include sputtering, filter-type arc ion plating, and electron beam-type ion plating. As a chemical vapor deposition (hereinafter referred to as CVD) method, there is a plasma CVD method. In addition, it can coat | cover by the method of forming into a film under the glow discharge plasma by RF, ECR, laser ablation, a microwave. Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to the following Example, It can change suitably by the field of use.

As Example 1 of the present invention, Co: 8 wt%, Cr: 0.5 wt%, VC: 0.2 wt%, hardness as a base material for evaluating the structure of a compound film mainly composed of boron nitride Used HRA94.2 fine grain cemented carbide inserts.
After sufficiently degreasing and cleaning the insert, it was placed on a jig in a film forming apparatus having a high frequency bias power source and a high frequency sputtering power source. The boron nitride target was installed in a sputtering evaporation source. When coating films other than boron nitride at the same time, they were installed in another sputtering evaporation source. The jig installed in the device revolves at 3 revolutions / minute. The inside of the film forming apparatus was evacuated to 3 × 10 ⁻⁴ Pa, and heated and evacuated so that the substrate temperature became 500 ° C. Next, Ar gas was introduced into the film forming apparatus, and Ar gas was ionized by discharging between the cathode electrode and the anode electrode. At this time, a pulsed bias voltage was applied to the substrate. The pulsed bias voltage was set such that the negative bias voltage was 200V, 90%, the positive bias voltage was 0V, 10%, and the pulse period was 20 kHz. The ionized Ar ions collide with the coated substrate, and the substrate is cleaned and activated. At this time, it is also effective to use a combination of gases such as Xe, Kr, and H _{2 in} order to further increase the cleaning efficiency and activity of the substrate. Ar and / or other gas were introduced into the container as needed, the whole pressure was set to 700 mPa, and the bias voltage was set to -100V. Of the plurality of sputtering evaporation sources arranged in the vessel, two boron nitride targets were mounted. Each 4 kW of electric power was supplied to generate sputtering discharge, and a coating having a total thickness of about 1 μm was coated on the coated substrate to which a high frequency bias voltage was applied. At this time, it is possible to form an A layer as an intermediate layer as necessary, which is a preferable mode. The means for containing N, C, O, S, B, or the like in the boron nitride film can be added as a pressure level of the introduced gas during film formation or as a mixed gas with nitrogen. The sample prepared according to the example uses a boron nitride target containing oxygen in the order of several hundred ppm, and oxygen gas is not added during film formation.

In order to confirm the structure of Example 1 of the present invention, a lattice image was observed with an acceleration voltage of 200 kV using a JEM-2010F type electrolytic emission transmission electron microscope manufactured by JEOL. In order to confirm the crystal structure of the film, a limited field diffraction image was taken. At this time, the camera length was set to 50 cm and the limited visual field region was set to 140 nm. In addition, in order to confirm the crystal structure of the nano area which is a minute part, micro electron diffraction was performed under the conditions of a camera length of 50 cm and a beam diameter of 1 nm. FIG. 1 shows a limited field diffraction image of the 140 nm diameter region of Example 1 of the present invention. FIG. 1 shows that the film of Example 1 of the present invention has a structure in which an amorphous phase and a crystalline phase are mixed. The crystalline phase was boron nitride consisting of hcp. In order to clarify the structure, the lattice image was observed. The result is shown in FIG. As can be seen from FIG. 2, amorphous boron nitride in a region having an equivalent circular diameter of less than 10 nm partially exists in the matrix phase of crystalline boron nitride in the boron nitride layer. The microelectron beam diffraction results corresponding to the regions 3 and 4 in FIG. 2 are shown in FIGS. From FIG. 3, it can be considered that the region 3 in which the lattice image is confirmed in the TEM image of FIG. 2 contains boron nitride having an hcp structure, but it is also considered that the structure is close to amorphous from the diffraction pattern. From the wide-area electron diffraction pattern shown in FIG. 1 and the lattice image observation result of FIG. 2, it is appropriate to think that the region 3 where the lattice image is observed contains boron nitride having an hcp structure. On the other hand, the region 4 where the lattice image shown in FIG. 4 is not confirmed indicates an amorphous structure from the diffraction pattern. Therefore, Example 1 of the present invention has a structure in which amorphous boron nitride is dispersed in hcp boron nitride. In addition, a structure in which amorphous boron nitride is dispersed in fcc boron nitride, a structure in which fcc boron nitride and amorphous boron nitride are dispersed in hcp boron nitride, or hcp boron nitride in fcc boron nitride and The effect of the present invention can be obtained even with a structure in which amorphous boron nitride is dispersed. The equivalent circular diameter in the amorphous boron nitride region was confirmed from a transmission electron micrograph.
In order to clarify the structure of the compound film mainly composed of boron nitride of Example 1 of the present invention, the qualitative elements of elements and the bonding state of boron were analyzed using a Quantum 2000 scanning X-ray photoelectron spectrometer manufactured by PHI. did. The measurement conditions were such that the X-ray source was Al-Kα (monochrome), the analysis region was 100 μm in diameter, and an electron neutralizing gun was used. A wide spectrum measured under these conditions is shown in FIG. FIG. 5 shows that the compound film mainly composed of boron nitride of Example 1 of the present invention contains boron, nitrogen, and oxygen. In addition, unavoidably mixed elements are included. FIG. 6 shows a spectrum attributed to the 1s orbital of the B element. FIG. 7 shows the separated spectrum. From FIG. 7, boron in the compound film mainly composed of boron nitride of Example 1 of the present invention has about 79% of bonds with nitrogen, about 5% of bonds with oxygen, and about 16% of bonds between single boron atoms. You can see that

  In order to evaluate the wear resistance of the coated member of the present invention, a two-blade ball end mill made of cemented carbide was simultaneously loaded and coated as a cutting test tool. This two-blade ball end mill is R5 mm. The base material composition was Co: 7% by weight, Cr: 0.7% by weight, VC: 0.2% by weight, hardness, HRA 94.1. Films generally conforming to the coating conditions of Invention Example 1 were prepared, and Invention Examples 2 to 17 were prepared. The coating conditions were variously changed in conditions such as mixed gas pressure at the time of film formation, bias voltage, and power of the sputtering evaporation source. Comparative Examples 18 and 19 were generally based on the coating conditions of Inventive Example 1, and various changes were made to conditions such as the gas pressure during deposition, the bias voltage, and the power of the sputtering evaporation source. In addition to the AIP method, the intermediate layer can be coated by sputtering, plasma CVD, or the like.

Examples 2 to 19 of the present invention are used as the cutting length or unstable machining state in which the flank wear width reaches 0.1 mm, for example, generation of sparks, abnormal noise, peeling of the machining surface, burning, breakage, etc. The cutting length that reached this condition was defined as the cutting life. Tables 1 and 2 are displayed by rounding off less than 100 m.
(Cutting conditions)
Cutting method: High-speed finishing Work material: FCD500
Cutting depth: axial direction, 1.2 mm, radial direction, 0.05 mm
Spindle speed: 40kmin- ¹
Table feed: 4m / min
Cutting oil: None, dry cutting

  Inventive Example 2 has a structure in which amorphous boron nitride is dispersed with hcp boron nitride as a matrix phase, and Inventive Example 3 has a nitrided amorphous boron nitride and fcc phase with hcp boron nitride as a matrix phase. It was a structure in which boron was dispersed. Inventive Examples 2 and 3, abnormal wear due to peeling was suppressed as compared with the Comparative Example, and as a result, excellent wear resistance was exhibited. Invention Example 4 shows a case where 0.2% of boron is present as an oxide. It was preferable from the viewpoint of lubricity that boron is present as an oxide in an amount of 0.3% or more. Invention Example 5 shows a case where the bond ratio of boron and oxygen is 11%. More preferable results were obtained when boron was present in an amount of less than 10% as an oxide. Invention Example 6 shows a case where the bonding ratio of boron and oxygen is 14.5%, and the bonding ratio of boron is 0.5% as a simple substance of boron. Invention Example 7 shows a case where the boron simple substance has a bond ratio of 27%. From this result, it is preferable to set the preferable bond ratio range in the case of existing as a simple boron to 1% or more and less than 25%. Inventive Example 8 shows a case where a boron nitride-based compound film similar to Inventive Example 1 is coated after the A layer is coated with a 2 μm TiN layer. Invention Example 9 shows a case where 100 layers of the TiN of the A layer and the boron nitride-based compound film of Invention Example 1 are alternately laminated. Invention Example 10 shows a case where the (TiAl) N layer is an A layer. Invention Example 11 shows a case where 1000 layers of the (TiAl) N layer of A layer and the boron nitride-based compound film of Invention Example 1 are alternately coated. Invention Example 12 shows a case where the (TiAl) N layer is coated, the (TiSi) N layer is coated, and the boron nitride-based compound film of Invention Example 1 is laminated thereon. Invention Example 13 shows the case where the A layer is coated with an (AlCr) N layer. Invention Example 14 shows the case where the A layer is coated with an (AlCrSi) N layer. Invention Example 15 shows the case where the A layer is covered with a Ti (CN) layer. Invention Example 16 shows the case where the A layer is covered with a (TiAlSi) N layer. As in Examples 8 to 16 of the present invention, the wear resistance was improved by using the A layer. Comparative Example 17 has a structure in which hcp boron nitride is used as a matrix phase and amorphous boron nitride is dispersed, and the equivalent circular diameter of the dispersed amorphous boron nitride region is 10 nm or more. From this, it was found that a structure of less than 10 nm is necessary. In Comparative Example 18, the wear resistance effect of boron nitride itself could hardly be confirmed due to peeling of the boron nitride film. In Comparative Example 19, boron was not qualified as an oxide. The boron nitride film became extremely brittle and the peeling progressed remarkably, and the wear resistance was not improved. In Comparative Example 18, the wear resistance effect of boron nitride itself could hardly be confirmed due to peeling of the boron nitride film. In Comparative Example 19, boron was not qualified as an oxide. The boron nitride film became extremely brittle and the peeling progressed remarkably, and the wear resistance was not improved.

FIG. 1 shows a limited field diffraction image of a 140 nm diameter region of Example 1 of the present invention. FIG. 2 shows a transmission electron micrograph of Example 1 of the present invention. FIG. 3 shows a microelectron beam diffraction image corresponding to the region 3 of FIG. FIG. 4 shows a microelectron beam diffraction image corresponding to the region 4 in FIG. FIG. 5 shows a wide spectrum by X-ray photoelectron spectroscopy analysis of Example 1 of the present invention. FIG. 6 shows the spectrum attributed to the 1s orbital of the B element in FIG. FIG. 7 shows the result of separating the spectrum of FIG.

Claims (5)

A member whose surface is coated with a compound film comprising boron, nitrogen, and oxygen, the compound film having a structure in which amorphous boron nitride is dispersed in crystalline boron nitride, and the compound film A covering member, wherein the area of an amorphous boron nitride region in a cross section is less than 10 nm when calculated as an equivalent circular diameter, which is a diameter when the area is replaced by a circle. The covering member according to claim 1, wherein boron in the compound film is present as an oxide and is 0.3% or more and less than 10% by mass. The covering member according to claim 1 or 2, wherein boron of the compound film is present as a simple substance and is 1% or more and less than 25% by mass. The covering member according to any one of claims 1 to 3, further comprising an A layer between the substrate and the compound film, wherein the A layer is composed of elements 4a, 5a, and 6a of the periodic table, Al, and Si. A covering member comprising one or more of selected nitrides, oxides, borides, sulfides, carbides, or a solid solution or a mixture thereof. The covering member according to claim 4, wherein the compound film and the A layer are alternately laminated in a range of 2 or more and less than 5000 layers.