JP5669107B2 - Cubic boron nitride coating method and material obtained thereby - Google Patents

Description

  The present invention is a novel material that is excellent in wear resistance, low friction, heat resistance, thermal conductivity, electrical insulation, etc., and can be applied to cutting tools, wear-resistant jigs, etc. The present invention relates to a material coated with boron nitride and a method for producing the same.

  Cubic Boron Nitride (cBN) is excellent in hardness, wear resistance, sliding property, thermal conductivity, and electrical insulation. It has been expected for many years as a material used for heat-resistant and highly insulating coatings.

  By coating cBN on a hard substrate, the hardness of cBN can be effectively utilized. Here, steel (for example, high-speed steel (high-speed steel)) is a hard material and used as a tool. Iron, cobalt and nickel-based metals (transition metals) are the main components. In addition, a cemented carbide represented by tungsten carbide (WC) contains an iron-based transition metal as a binder phase.

When boron nitride (BN) is coated on these materials, sp ² -bonded boron nitride (eg hexagonal boron nitride (eg hexagonal boron nitride) is used due to the catalytic action of ferrous metals.
Boron Nitride (hBN), turbostratic Boron Nitride (tBN), and amorphous Boron Nitride (aBN) Met.
In order to prevent the interference caused by the catalytic action of the iron-based metal, a method of removing the iron-based metal in the vicinity of the substrate surface by acid treatment has been proposed in the case of a cemented carbide having the iron-based metal as a binder phase.

  However, the method of removing the iron-based metal has a problem that the surface after the acid treatment is only a pure carbonized phase and the strength in the vicinity of the surface is lowered. In addition, even if the surface iron-based metal is once removed, the transition metal of the binder diffuses from the inside of the base material to the base material surface due to the high temperature treatment at the time of forming the cBN film, thereby obstructing the generation of cBN. There is a problem of doing.

  As a conventional cubic boron nitride coating method, there is a method in which a metal such as Ti or Zr or a metal nitride is interposed as an intermediate layer between cBN and a base material (for example, Patent Document 1). In addition, as a conventional cubic boron nitride coating method, in order to improve adhesion to a super hard material, boron is coated and then iron-based metal is borated by thermal diffusion or reacts with a gas containing boron. A method is proposed in which the substrate is borated to seal off its catalytic action (for example, Patent Document 2).

JP 2010-099916 A JP-A-4-12442834

  However, in the conventional cubic boron nitride coating method, when an intermediate layer is provided, the manufacturing process becomes complicated and the cost increases, and in some cases, the hardness and strength of the intermediate layer are insufficient, It has the subject that the mechanical strength of the whole composite material falls. In addition, there is a case where the intermediate layer or the cBN film is likely to be peeled off due to mismatch of thermal expansion coefficients, which requires a precise control in the manufacturing process, and there is a problem that the cost in the case of implementation is increased.

Further, in the conventional cubic boron nitride coating method, when boring the substrate, boriding is simply performed by thermal diffusion, so it is difficult to control the degree of boriding (boron). If insufficient, the iron-based metal in the surface layer remains unborated. In addition, when boring of the iron-based metal is insufficient, there is a problem that an sp ² -bonded BN phase is likely to be generated during BN coating due to its catalytic action.

Conversely, when boron is excessive, for example, a cemented carbide represented by tungsten carbide (WC) has a problem that solid boron remains on the WC because the main component of WC is not easily borated. When there is an excess of solid boron on WC, there is a problem that cBN cannot be formed by the nitriding reaction, and an sp ² -bonded BN phase is easily generated.
For these reasons, techniques for performing cBN coating on substrates containing ferrous transition metals such as cemented carbide and high speed steel are not well established at present.

The present invention has been made to solve the above-described problems, and suppresses the formation of sp ² -bonded BN on a substrate containing an iron-based transition metal and prevents interference due to the catalytic action of the iron-based metal. Another object of the present invention is to provide a cubic boron nitride coating technique that improves the adhesion and uniformity of a cubic boron nitride film.

  As a result of diligent research, the inventors of the present invention have achieved the above object by reliably boring (boriding) or siliciding (siliciding) part of the iron-based transition metal itself contained in the base material. It was found that this can be achieved, and the present invention was derived.

  Thus, the present invention provides a cubic boron nitride coating method including a step of coating a film mainly composed of cubic boron nitride on a substrate containing an iron-based transition metal, and coating the cubic boron nitride film. The present invention provides a method characterized by including a pre-process for forming a boride or silicide of the transition metal contained in the base material on the base material before the step of performing the step.

A phase diagram (phase diagram) of a cobalt-boron system is shown. 1 schematically shows a WC-Co superalloy substrate coated with cubic boron nitride obtained by the present invention. 1 schematically shows a WC-Co superalloy substrate coated with cubic boron nitride obtained by a conventional method. The Raman scattering spectrum figure of the cubic boron nitride film obtained by Example 1 is shown. The X-ray-diffraction figure of the cubic boron nitride thin film obtained by Example 4 is shown. The X-ray-diffraction figure of the cubic boron nitride thin film obtained by the comparative example 4 is shown. The Raman scattering spectrum figure of the cubic boron nitride film obtained by Example 4 is shown. An iron-boron phase diagram (phase diagram) is shown. A phase diagram (phase diagram) of the nickel-boron system is shown.

<Type of substrate>
The base material containing an iron-based transition metal to which the coating method of the present invention is applied is a cemented carbide having an iron-based transition metal as a binder phase (binder), or a steel having an iron-based transition metal as a constituent ( Particularly high speed steel). Here, in the context of the present invention, iron-based transition metals are chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co) and nickel (Ni), and particularly iron (Fe). , Cobalt (Co) and nickel (Ni). As the cemented carbide, iron such as WC-Co alloy, WC-TiC-Co alloy, WC-TaC-Co alloy, WC-Ni alloy, WC-Ni-Cr alloy, TiN-Ni alloy, etc. , Cobalt and nickel as binders. Of these, the most widely used cemented carbide is a WC-Co alloy, which has hardness, toughness, and deficiency as an alloy due to the hardness of WC, high temperature strength, etc. and good adhesion of Co to WC. This is because the mechanical properties such as properties are particularly excellent. High speed steel is often abbreviated as “His” or “HSS”.

  The present invention is effective for coating cBN on such a high-hardness base material, and the obtained material is an application field in which the high hardness, heat resistance, oxidation resistance, low wear resistance, etc. of cBN can be effectively utilized ( For example, cutting tools, grinding tools, drills and other processing tools, anti-wear tools such as dies, dies and bonding tools, and high-temperature and oxidation-resistant low-friction sliding members such as protective films for magnetic storage media) Can do. The present invention is particularly preferably applied to a substrate containing cobalt (Co) as an iron-based transition metal, such as a WC-Co-based cemented carbide.

<Boride formation>
In a preferred embodiment of the cBN coating method according to the present invention, the transition metal boride (boride) is formed on the substrate prior to coating the cubic boron nitride on the substrate containing the iron-based transition metal. A pre-process is included.

  This pre-process for forming the boride includes coating boron on a substrate containing an iron-based transition metal, and then heating to a temperature at which the transition metal and boron melt, Cooling to a temperature at which boron solidifies. In particular, the heating temperature is preferably equal to or higher than the eutectic point of the eutectic having the most boron-rich composition in a two-component system composed of an iron-based transition metal and boron.

By such a pre-boride formation step, a solid solution of iron-based transition metal and boron (especially boron-rich solid solution) is formed in advance as a boride on the base material, thereby generating sp ² -bonded BN. It is considered that the cBN phase is coated with suppression.

  Hereinafter, the formation of boride according to the present invention will be considered by taking as an example the case where Co (cobalt) is contained as an iron-based transition metal, such as a cemented carbide substrate made of cobalt-containing tungsten carbide. FIG. 1 is a phase diagram (under normal pressure) of a cobalt-boron binary system. A phase diagram of an iron-based transition metal such as cobalt and boron generally shows a plurality of eutectic points (temperatures) at which a melting curve (solidification curve) shows a plurality of minimum values, as shown in the figure.

  According to the present invention, with reference to this state diagram, heating was performed as a boring condition up to a temperature at which cobalt and boron melt (liquefy) (temperature at which a region indicated by L in the state diagram of FIG. Exists). Then, it cools (rapidly cools) to a temperature at which cobalt and boron are solidified (a temperature at which a region indicated by S in the state diagram in the figure exists).

  Here, in the Co-B system in which the present invention is involved, since the substrate is coated with boron in advance, the boron (B) rich region in the state diagram shown in the figure, that is, the right side of the figure. However, it is thought that it can contribute to setting temperature conditions.

That is, in the case of the Co—B system, as a preferred embodiment according to the present invention, the eutectic point of the eutectic of the most boron-rich composition in the binary system composed of Co (cobalt) and B (boron) [in the state diagram of FIG. , B is 61% Co-B eutectic point (percent of atoms), and then heated to a temperature equal to or higher than 1350 ° C. and then below the eutectic point (in the state diagram of the figure, S ₁ + S ₂ By cooling to the temperature where the indicated region exists: for example, 1000 ° C. or lower), a boride (B-rich CoB solid solution) layer is formed (formed) on the substrate, and the Co phase or Co-rich layer is formed. It is believed that no phase exists.

  For other iron-based transition metals, similarly to the above, temperature conditions for forming borides can be determined with reference to the phase diagram. For example, FIGS. 8 and 9 show Fe-B phase diagrams and Ni-B phase diagrams that can be used to define boriding conditions for substrates containing iron and nickel, respectively, as iron-based transition metals. It is a state diagram. In any case, after heating to a temperature at which iron and boron or nickel and boron are melted (temperature in the region indicated by L in those phase diagrams), to a temperature at which iron and boron or nickel boron are solidified. Cool down quickly. In particular, in the Fe-B system, heating to the eutectic point (1500 ° C.) or higher shown in the figure, and in the Ni-B system, heating to the eutectic point (1018 ° C.) or higher shown in the figure, followed by rapid cooling Is preferred.

  When the temperature at which the melt (liquid) exists is low, cBN deposition is possible even in the presence of the melt. Co and B in the liquid state are wetted due to the affinity between Co and WC even when solid boron is present on WC grains where borides are difficult to form, such as WC-Co cemented carbide. The interdiffusion of boron and binder phase Co is promoted, and further boration of WC is promoted, and uniform cBN coating can be facilitated.

  Thus, in the boride forming step according to the present invention, first, boron (boron) is supplied and boron coating is performed. Boron coating on the substrate can be performed by devising known means. For example, using boron trifluoride as a boron source, chemical vapor deposition (CVD: chemical vapor deposition), electron Either physical vapor deposition (PVD: physical vapor deposition) such as beam deposition, ion beam deposition, ion plating, sputtering, laser ablation, or seeding of solid boron powder, or a combination thereof. be able to. The time required for boron coating is generally 5 to 20 minutes, for example, 10 minutes.

  After the boron coating, as already described in detail, the substrate is heated to a predetermined temperature and held for a predetermined time, and then cooled. The time for holding at the predetermined heating temperature is generally 1 minute to 10 minutes, and the cooling is preferably rapidly cooled from the predetermined heating temperature to the cooling temperature in 1 minute or less.

  The boride formation process described above can be performed in vacuum, in an inert gas such as argon, in nitrogen gas, or in a mixed gas of inert gas and nitrogen. At this time, when performed in a gas containing hydrogen or in a plasma containing hydrogen, the transition metal and boron can be eutectic at a considerably lower temperature than in an inert gas atmosphere. A boride (solid solution) can be formed. This is presumably because the addition of hydrogen increases the component by one and lowers the melting point. The reaction rate of the eutectic operation can be increased in the plasma containing hydrogen than in the gas containing hydrogen.

<Formation of silicides>
In another preferred embodiment of the cBN coating method according to the present invention, a pre-process for forming a silicide (silicide) of the transition metal on a substrate containing an iron-based transition metal is included.
Since B (boron) reacts slowly with iron-based transition metals such as Co (cobalt), it can be cooled from a liquid to a solid by melting B and the transition metal so that B can easily enter Co. is necessary. On the other hand, since Si (silicon: silicon) easily reacts with iron-based transition metals such as Co, the transition can be achieved by vapor deposition on the surface of the transition metal at high temperatures by various conventionally known means. Metal silicides can be obtained. That is, the pre-process for forming a silicide according to the present invention is performed by using a chemical vapor deposition method (CVD: chemical vapor deposition method) or a physical vapor deposition method (PVD: physical vapor deposition method) from a raw material serving as a silicon source. Forming the transition metal silicide by depositing silicon on the surface of the substrate containing the iron-based transition metal.

As the CVD method, plasma CVD, photo-CVD, or the like is known, but plasma CVD is suitable for the present invention. By depositing a source gas serving as a silicon supply source on a heated substrate in an atmosphere of argon or argon + hydrogen, an iron-based transition metal silicide is formed. As a source gas for the CVD method, a gas containing silicon such as silane (SiH ₄ ), disilane (Si ₂ H ₆ ), dichlorosilane (SiH ₂ Cl ₂ ), silicon tetrachloride (SiCl ₄ ), or monomethylsilane (SiH _3). Examples thereof include gases containing silicon and / or carbon such as CH ₃ ), tetramethyl silicon (Si (CH ₄ ) ₄ ), and tetraethoxy silicon (TEOS: Si (OC ₂ H ₅ ) ₄ ).

  By setting the substrate temperature to 300 ° C. or higher, preferably 500 ° C. or higher, the iron-based transition metal can be directly silicided. In the case of a cemented carbide having an iron-based transition metal as a binder phase, the cemented carbide phase (for example, in the case of cobalt-containing tungsten carbide (WC-Co), the WC phase is applicable) is an iron-based transition metal. Since the silicidation reaction is slower than that of the phase and is not sufficiently silicided at about 500 ° C., the iron-based transition metal phase can be used under conditions where silicon is easily vaporized (for example, CVD at low temperature or silicidation in hydrogen plasma). Only can be silicified. When the substrate is heated to 800 ° C. or higher, the cemented carbide phase is also silicided.

  Examples of the PVD method include ion beam vapor deposition, ion plating, or electron beam vapor deposition or sputtering using solid silicon as a target, and a preferable method is a high frequency sputtering method in an inert gas such as argon. In the case of PVD, even when the initial solid silicon present on the surface of the substrate is thin, the solid silicon is absorbed and silicified into the binder phase by subsequent heating to form a sufficient silicide layer.

<Coating of cBN>
As described above, after the boride or silicide of the metal is formed on the base material containing the iron-based transition metal, coating (film formation) of cBN is performed. This cBN film is formed by using a known method of chemical vapor deposition (CVD) or physical vapor deposition (PVD) of cubic boron nitride or a combination thereof. Can do. That is, it is possible to use a plasma CVD method using various high-density plasmas such as plasma jet, microwave plasma, inductively coupled plasma, and electron cyclotron resonance plasma, PVD methods such as bias sputtering, ion beam evaporation, and ion beam assisted evaporation. it can.

  Among these, the plasma CVD method using fluorine is particularly preferable. That is, a boron source such as diborane and boron trifluoride, a nitrogen source such as nitrogen and ammonia, and a fluorine source such as boron trifluoride, fluorine and hydrogen fluoride are supplied into the gas phase, and the gas phase is converted into plasma. Activate and deposit cubic boron nitride onto the substrate. By performing this CVD, as will be described later, a cBN film having particularly good crystallinity can be coated with high adhesion.

  When cBN is coated by the plasma CVD method using fluorine, a bias voltage is applied to the substrate with respect to a reaction vessel wall or a reference electrode installed in the reaction vessel. One or both of hydrogen and a rare gas can be added for reaction and plasma control. As a kind of plasma, various high-density plasmas such as plasma jet, microwave plasma, inductively coupled plasma, and electron cyclotron resonance plasma can be used.

  As the substrate bias, any of direct current, alternating current, high frequency, a stack of them, or a power source obtained by pulsing them can be used. The optimum bias voltage varies depending on the gas pressure, gas composition, substrate temperature, etc., but a positive bias of about 0 to −150 V or about 0 to +100 V can be used depending on the type of plasma.

<Material properties>
According to the present invention, it is possible to obtain an excellent coating material in which a highly crystalline cBN is coated with a high degree of adhesion on a base material such as cemented carbide or high speed steel.
That is, the obtained cBN film has a peak in which either or both of Raman scattering by phonons in the optical longitudinal wave mode of cBN and Raman scattering by phonons in the optical transverse wave mode are 50 cm ⁻¹ or less in the Raman spectrum. Or the half width of 2θ of the reflection peak of any one of (111), (200), (220), and (311) of the cubic boron nitride of the surface film by thin film X-ray diffraction Have high crystallinity of 1.5, 2.5, 2.5 or 3 degrees or less, respectively. Further, when the crystallinity is good, the half width of the Raman peak is 25 cm ⁻¹ or less, and the reflection peak of any one of (111), (200), (220), and (311) of X-ray diffraction is used. The half width of 2θ is 1, 1.5, 1.5, 2 degrees or less, respectively.

  In addition, the cBN coating material obtained by the present invention has high cBN adhesion, and when the adhesion is measured by a scratch test, when the boride according to the present invention is formed, the peel load is 30 N or more. When the silicide according to the present invention is formed, it is confirmed that it is 10 N or more.

  According to the present invention, how a cBN coating material having excellent adhesion can be obtained will be schematically described as an example of a WC-Co cemented carbide as follows: That is, FIG. As shown, a boride or silicide phase 2 exists as an intermediate layer between the substrate 3 (consisting of the WC phase 31 and the Co phase 32) and the cBN film 1. More specifically, phase 2 of boride or silicide is mainly formed of tungsten boride or silicide on the surface in contact with WC phase 31, and cobalt boride or silicide on the surface in contact with Co phase 32. Is mainly occurring. In the case of forming a silicide, as described above, the silicide may be formed exclusively with Co by means such as adjusting the temperature of the base material, and the WC phase may be directly coated with cBN. In addition, when cBN is directly coated on the super hard material phase (WC phase), there is a characteristic that the elastic modulus is high. On the other hand, when silicide is present on the entire surface of the substrate, toughness is present. There is a characteristic that it is high. Since there is such a difference in characteristics depending on the coating, both can be used properly according to the application.

In contrast, in the conventional cBN coating method, as shown in FIG. 3, the sp ² -bonded BN film 100 is formed on the substrate 3 (FIG. 3 (a)), or when cBN is coated. The thick sp ² -bonded BN film 100 may be formed on the substrate 3 ((b) in the same figure), and the cBN coating on the sp ² -bonded BN film 100 was easily peeled off. However, in the cBN coating method of the present invention, Co (cobalt) becomes a boride (solid solution with boron) or a silicide, so that the catalytic action on sp ² -bonded BN formation is suppressed, as shown in FIG. , CBN film formation and adhesion can be improved. The cBN film of the present invention may have a very small amount of sp ² -bonded BN on the substrate side. In this case, the adhesion of the cBN film is also good.

  In the practice of the present invention, when chemical vapor deposition (CVD: chemical vapor deposition) is used to form a boride or silicide and then coat a film mainly composed of cubic boron nitride, supply By switching the gas, it can be performed in common in the same apparatus, and the manufacturing process can be simplified and the work load can be reduced. Even when one or a plurality of steps of boride or silicide formation and cBN coating is a PVD method, all steps can be performed in the same apparatus by devising those steps.

  In the above description, the cemented carbide having Co (cobalt) as the binder phase is mainly described as the base material to be cBN coated. However, the present invention is not limited to other types of substrates containing iron-based transition metals. The same applies to the material. Even in this case, a cBN coating equivalent to the cBN coating described above can be performed.

EXAMPLES Hereinafter, examples will be shown to describe the features of the present invention more specifically, but the present invention is not limited to these examples.
Of the following examples, Example 1-3 is an example of forming a boride before cBN coating, and Examples 4 and 5 are examples of forming a silicide before cBN coating. The peel load is measured by a scratch test in which a diamond indenter is pressed and pulled while increasing the load.

  A plasma of argon, boron trifluoride and hydrogen gas (20: 0.01: 0.1) is used for 10 minutes on a 6% cobalt-containing tungsten carbide (hereinafter referred to as WC-6% Co) substrate at a substrate temperature of 700 ° C. A boron film was deposited and heated as it was in argon-hydrogen plasma (20: 0.1) to 1100 ° C. for 5 minutes and then cooled to 500 ° C. to form a boride. The cBN film was then reacted by plasma CVD from argon-boron trifluoride-hydrogen-nitrogen gas (20: 0.003: 0.005: 1.5) at a substrate temperature of 850 ° C. and a substrate bias of −85 V for 20 minutes. Was deposited.

  These processes were all carried out using arc jet plasma at a pressure of 50 Torr in the same reactor. The thickness of this cBN film was 4 microns. When the adhesion was examined with a scratch tester with acoustic emission, the peel load was 40N.

FIG. 4 shows the Raman scattering spectrum of this film. The half-value widths of the Raman scattering peak due to the optical longitudinal wave mode phonon or the Raman scattering peak due to the optical transverse wave mode phonon are 20.1 and 39.1 cm ^−1, respectively. Met.

(Comparative Example 1)
In the same apparatus as in Example 1, an argon-boron trifluoride-hydrogen-nitrogen gas (20: 0.003: 0.005: 1.5) was formed on a WC-6% Co substrate without a boron coating process. When the reaction was carried out for 20 minutes at a substrate temperature of 850 ° C. and a substrate bias of −85 V by plasma CVD from (1), only a soft and easy-to-peel film composed mainly of sp ² -bonded BN was obtained. .

(Comparative Example 2)
Although the same process as in Example 1 was carried out, and a BN film was formed without heating at 1100 ° C. in an argon-hydrogen plasma, a film in which cBN was formed on sp ² -bonded BN was obtained. It peeled off within a few hours after removal.

(Comparative Example 3)
The same process as in Example 1, but instead of heating at 1100 ° C. in an argon-hydrogen plasma, the film obtained by BN deposition after 5 minutes of heating at 1100 ° C. in an argon only plasma is The film was formed by cBN on sp ² -bonded BN, but the peel load by the scratch test was inferior to <1N in adhesion.

  The same process as Example 1, but after heating at 1370 ° C. for 1 minute in argon-only plasma instead of argon-hydrogen plasma, the cBN film obtained by film formation at 850 ° C. has a peeling load of 30 N The adhesion was shown.

A boron film of about 1 μm was coated on a WC-6% Co substrate by high frequency sputtering in argon. Thereafter, the same arc jet plasma CVD apparatus as in Example 1 was heated in argon plasma at 1370 ° C. for 1 minute, then cooled to 500 ° C., and argon-boron trifluoride-hydrogen-nitrogen gas (20: 0.003: 0) 0.005: 1.5), a cBN film was deposited by a reaction for 20 minutes at a substrate temperature of 850 ° C. and a substrate bias of −85 V by plasma CVD at 50 Torr. The cBN film obtained by film formation at 850 ° C. exhibited adhesion with a peeling load of 30N.
The results of these examples and comparative examples are summarized in the following table and listed.

  From a plasma of argon, silicon tetrachloride and hydrogen gas (20: 0.005: 0.01), WC-6% Co is silicided (silicified) for 10 minutes at a substrate temperature of 800 ° C., and then argon, three fluorine A cBN film was deposited by reaction for 20 minutes at a substrate temperature of 850 ° C. by plasma CVD from boron fluoride, hydrogen, and nitrogen gas (20: 0.003: 0.005: 1.5). All these processes used arc jet plasma under the pressure of 50 Torr in the same reactor. The thickness of this cBN film was 4 microns.

A thin film X-ray diffraction pattern of this film is shown in FIG. The sp ² -bonded BN peak is not conspicuous, and a cBN peak is observed, and particularly the 111 reflection is a sharp peak. In addition, WSi ₂ and CoSi appear.

The Raman scattering spectrum of this film is shown in FIG. The half widths of Raman scattering by phonons in the optical longitudinal wave mode and Raman scattering by phonons in the optical transverse wave mode were 20.4 and 34.1 cm ⁻¹ , respectively. This film had good adhesion, and in the adhesion test by the scratch test, the peeling load was 40N.

(Comparative Example 4)
In the same process as in Example 4, when the BN film was formed without the first silicidation treatment, as shown in the thin film X-ray diffraction diagram of FIG. 6, the sp ² -bonded BN was used as the main component (tBN). As a result, only a film that was easy to peel off was obtained. The film thickness was 4.3 microns. cBN is very weak and tBN appears most strongly. When this film was subjected to an adhesion test by a scratch test, the peel load was 1 N or less.

  A silicon film having a thickness of about 100 nm was coated on a 6% cobalt-containing tungsten carbide (hereinafter referred to as WC-6% Co) substrate by high-frequency sputtering in argon. This was subjected to high frequency induction plasma CVD using helium-nitrogen-boron trifluoride-hydrogen gas (80: 20: 1.5: 15) and a bias voltage of +30 V was used at a substrate temperature of 700 ° C. and a pressure of 300 mTorr. A film having a thickness of about 2 microns containing cBN as a main component was obtained by film formation for 30 minutes. When this film was subjected to an adhesion test using a scratch tester with acoustic emission, the peel load was 10 N.

(Comparative Example 5)
Using a base material of the same material, without a silicon coating, by a high frequency induction plasma CVD method from helium-nitrogen-boron trifluoride-hydrogen gas (80: 20: 1.5: 15) at a substrate temperature of 700 ° C. Under a pressure of 300 mTorr, a BN film was coated using a bias voltage of +30 V to obtain a film about 2 microns thick consisting of cBN and sp ² bonded BN. When this film was subjected to an adhesion test by a scratch test, the peel load was 1 N or less.

  A c-BN film-coated composite with high adhesion to a high-hardness substrate. For coatings such as cutting tools, grinding tools, and drills that require high hardness, high wear resistance, high heat resistance, and high thermal conductivity. And application to wear-resistant coatings are expected.

Claims (5)

In a cubic boron nitride coating method including a step of coating a film mainly composed of cubic boron nitride on a substrate containing an iron-based transition metal,
Before the step of coating the cubic boron nitride film, the step of forming a silicide of the transition metal contained in the base material on the base material, wherein the pre-process includes chemical vapor deposition Characterized by forming a silicide of the transition metal by depositing silicon on the surface of the substrate containing the iron-based transition metal by a (CVD) method or a physical vapor deposition (PVD) method. Method.   The cubic boron nitride coating method according to claim 8, wherein the pre-process and the cubic boron nitride film coating process are performed in the same apparatus.   The cubic boron nitride coating method according to claim 8 or 9, wherein the base material is a cemented carbide having the iron-based transition metal as a binder phase.   The cubic boron nitride coating method according to claim 10, wherein the substrate is a WC—Co cemented carbide. A coating material comprising a substrate containing a silicided iron-based transition metal and coated with a film mainly composed of cubic boron nitride, wherein the coated cubic boron nitride has an optical longitudinal wave mode. One or both of Raman scattering due to phonons and Raman scattering due to optical transverse wave mode phonons show a peak of 50 cm ⁻¹ or less, and have a peeling load of 10 N or more by a scratch test. Coating material.

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