JPH04168263A - Boron nitride coated laminated material - Google Patents

Abstract

PURPOSE:To enhance adhesive strength to the base material and to improve toughness by forming a metal film of a group IVa, Va or VIa element as the 1st layer, a boron film as the 2nd layer and a cubic boron nitride film as the outermost layer. CONSTITUTION:A metal film of a group IVa, Va or VIa element is formed as the 1st layer on the surface of a base material. A boron film and/or a boron- rich amorphous boron nitride film having >=1.5 atomic ratio of B to N is formed as the 2nd layer on the 1st layer. A cubic boron nitride film is then formed as the outermost layer on the 2nd layer. The activated boron of the 2nd layer reacts with the metal (e.g. Ti) of the 1st layer to form a high strength Ti-B compd. between the 1st and the 2nd layers.

Description

Detailed Description of the Invention [Field of Application in A Business] The present invention relates to a boron nitride-coated composite material that has excellent wear resistance, heat resistance, electrical insulation, thermal conductivity, etc., and is particularly applicable to the field of electronic materials. The present invention relates to a composite material useful as a hard wear-resistant coating material in the field of highly thermally conductive substrates and cutting tools.

[Prior art] Cubic boron nitride (Cubic Boron N1tri)
CBN (hereinafter referred to as cBN) is useful as an IC heat sink or passivation film due to its excellent electrical insulation and thermal conductivity, and is extremely hard and has excellent abrasion resistance and heat resistance. It is also highly useful as a coating material for the base material surfaces of metal and ceramic machine tools, and is particularly attracting attention as a surface coating material for cutting tools for difficult-to-cut materials and high-speed cutting tools.

In addition, regarding the formation method of cBN thin film, physical vapor deposition method (
Various studies are underway using PVD (PVD) and chemical vapor deposition (CVD).

[Problems to be Solved by the Invention] However, since all of these methods achieve a cubic phase (i.e., aBH film) by the bombardment effect of accelerated ions, the internal stress of the aBH film is large, making it difficult to use metals or ceramics. Generally, the adhesion with the base material made of such materials is insufficient, and peeling is likely to occur. Particularly when a thick film is formed, cracks are likely to occur, making it difficult to manufacture an aBH film with a thickness of several OA or more.

The present invention was made in view of these circumstances, and it is an object of the present invention to provide a composite material with good adhesion between an aBH film and a base material.

[Means for Solving the Problems] The composite material of the present invention has at least a boron nitride coating layer on the surface of the base material, and the first layer that may be in contact with the surface of the base material is a group IVa, Va. One or two selected from the group consisting of elements of group Vla and group Vla.
A B-rich amorphous film having a B film and/or a B/N (atomic ratio) of 1.5 or more as a second layer in contact with the first layer. The main feature is that it has a boron nitride film layer, and at least the outermost layer has a cubic boron nitride film layer.

[The working core aBH film has the above-mentioned drawbacks, but amorphous BN
(hereinafter referred to as aBN) is a material that has excellent adhesion to various materials. However, aBN (that is, aBN with a B/N of 1 or less) is soft, and its wear resistance does not satisfy the characteristics required as a coating material for cutting tools.

However, the present inventors studied this aBH and found that B/
When the N ratio is increased to 1.5 or more, the hardness increases without decreasing the adhesion to the material (Hv: 3000 kg/mm
2 or more) was achieved, and also showed good adhesion to cBN. The present inventors conducted further research based on the policy of using such highly hardened aBN as a base material for cBH, and as a result, they found that the B/N was 1. A rich in B from 5 to 9
It was discovered that a composite material having a BNlli layer and a cBN film layer as the outermost layer exhibits excellent properties,
Since its technical significance was recognized, an application was filed earlier (Japanese Patent Application Laid-open No. 171868/1983). In this technology, aBNM
Due to its characteristics, the layer exhibits excellent adhesion to the base material, and also has sufficient adhesion to the cBN film layer that constitutes the outermost layer, and has the ability to firmly support the cBN film layer due to its excellent high hardness. I was able to demonstrate. That is, the aBN film base layer exerted a function of alleviating the internal stress generated during the formation of the cBN film, and an aBHQ layer with good adhesion could be formed.

However, it has been found that the above composite material may not have sufficient adhesion to the base material depending on the conditions in which it is used. Therefore, the present inventors investigated from various angles in order to develop a composite material with higher performance. As a result, a metal film made of one or more elements selected from the group consisting of IVa group, Va group, and Vla group elements is formed as a first layer in contact with the base material, and on the first layer. , B/N is 1
．． It was discovered that by forming aBN [rich in B of 5 or more], the adhesion to the base material can be further strengthened, resulting in a composite material with better properties, and the present invention has been completed.

According to the research of the present inventors, as the second layer, B/N
It has been found that excellent characteristics can be exhibited not only in the case of a B-rich aBNwA with a B content of 1.5 or more alone, but also in the case of a B-only layer or a layer containing both of these. Therefore, the second layer in the present invention is intended to include any of these.

For example, FIG. 1(A) shows a cross-sectional view of a composite material in which a single film of B11j or B-rich aBN (B(rich)-aBN) is formed as the second layer. Figure (B) shows B film and B (rich) as the second layer.
-a This is a case where a BN film is laminated. In any case, due to the reaction between the first layer and the second layer, an intermetallic compound layer as shown in FIG. 2 is formed, and the first layer and the second layer are firmly bonded.

The operation of the present invention will be specifically explained using an example of using Tt as the first layer. That is, when a cBN film and/or BWA is formed as the second layer, B in an ionized or activated state reacts with Ti in the first layer, and
A high-strength Ti-B compound (TiBz, etc.) is formed between the layers. In addition, the internal stress generated during the formation of the cBN film is alleviated by the Ti layer, which has good adhesion to the base material, and the Ti-B
A cBN layer with good adhesion can be formed by the based compound layer. Furthermore, since the 'M2 layer has high hardness, the film strength does not decrease.

When the B/N in the cBN layer as the second layer is less than 1.5, there is no problem with adhesion, but the hardness becomes low and the cBN layer i layer cannot be supported sufficiently.

That is, the composite material according to the present invention is often used under harsh conditions by taking advantage of the excellent wear resistance of the cBN film layer.
In such a case, even if the cBN layer exhibits excellent characteristics such as wear resistance, if the second layer is soft, the function of the cBN will be insufficient as a result, and peeling or chipping will occur.

In the composite material of the present invention, the second layer made of the cBN film and the outermost layer made of the cBN layer may be in direct contact with each other in a discontinuous state in terms of concentration. As shown in FIG. 3 (component composition by Auger spectroscopy), the layer has a concentration gradient such that the side in contact with the base material has a high B/N composition and the B/N decreases toward the outer surface, In addition, if the outermost layer of the aBNWi base layer is configured to have the same B/N as the cBN layer, the adhesion between the aBN film base layer and the outermost layer of the cBN film will be even better, thereby further increasing the film strength. be able to.

As mentioned above, the first layer in the present invention includes IVa group, V
1 selected from the group consisting of elements of group a and group Vla
The basic structure is a metal layer consisting of a species or two or more elements, but from the viewpoint of improving strength, the 341 layer may contain B, Such a configuration is also included within the technical scope of the present invention. As a specific means for forming such a first layer, for example, when forming the first layer, Ti and B may be simultaneously vapor-deposited.

The composite material according to the present invention has a three-layer structure in which the first layer, the second layer, and the outermost layer are laminated on the base material, but from the viewpoint of obtaining higher toughness, the first layer It is also possible to obtain a high-hardness, high-toughness thick film by forming a multilayer structure in which a plurality of layers and a plurality of second layers are alternately laminated, and forming a cBN layer as the outermost layer. It is also effective to use a three-layer structure of a first layer, a second layer, and a cubic boron nitride layer, or a multi-layered structure as the base layer.

On the other hand, from the viewpoint of further improving the adhesion between the first layer and the second layer in the composite material of the present invention, heat treatment at a temperature of 600°C or higher in a vacuum or nitrogen atmosphere is also effective. This makes it possible to increase the thickness of the metal layer-B-based reaction layer (for example, the above-mentioned two TiB layers), and has the effect of relieving internal stress.

The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to the following Examples, and any design changes in accordance with the spirit of the above and below are within the technical scope of the present invention. It is something that can be done.

[Example] 2f melted by electron beam! The cBN-coated composite material of the present invention was fabricated using an ion blating device having a water-cooled crucible into which metals of various types can be charged separately. A mixed gas of N2+Ar was used as the introduced gas at this time.

The evaporation and ionization of the gas by electron beam melting utilized a discharge between a positive electrode placed above the crucible and a thermionic electron supply filament, and activated the evaporated particles as they passed through the discharge region. The substrate was attached above the crucible, and high frequency power (13.56 MHz) was applied to the substrate so that the insulator could be uniformly formed.

Ti and B were charged into an electron beam melting crucible, the vacuum chamber was evacuated to 5 x 10-'Torr, and the temperature of the substrate was gradually raised to 400°C using a heater, gas was released, and the final vacuum was reached. degree 2 x 10-'T
It was set as orr. First, Ti is evaporated with an electron beam to form a first layer of a predetermined thickness while observing with a film thickness monitor. Then, a mixed gas of N2 + Ar is introduced and B is evaporated, and the composition of the BN film is controlled by outputting an electron beam. The aBN layer was formed by gradually lowering B/N from B-rich BN to create a composition gradient, and finally the cBN layer was formed as the outermost layer. In addition, when Zr, Nb, W, etc. are used instead of Ti as the first layer, when a part of the second layer on the base material side is a single B layer, or when the first layer and the second layer are multilayered. Composite materials were also created for cases where Further, some of the composite materials (Nos. 7 to 9) were subjected to heat treatment at a temperature of 600° C. or higher in an N2 atmosphere.

The obtained composite material was subjected to a scratch test using the AE (Acousting Emission) detection method.
The adhesion of the coating layer was investigated. Table 1 shows the composition of each composite material and the results of the scratch test. Table 1 shows the substrates in which only the cBN layer is formed (No. 10.
12), and those in which only the second layer (gradient composition N) was formed without forming the first layer (No. 11. 13) were also shown as comparative examples.

As is clear from Table 1, the composite material according to the present invention (No.
, 1 to 9), it can be seen that the adhesion between cBN and the base material is extremely good. Also, by making it composite, the toughness was improved and the film thickness could be increased.

[Effects of the Invention] The present invention is constructed as described above, and it is possible to obtain high adhesion strength to the base material without reducing the high hardness, which is a characteristic of cBN, and to reduce the Toughness can now be corrected by compounding. In particular, the composite material according to the present invention is expected to fully demonstrate its effectiveness as a cutting tool etc. by utilizing the above characteristics.

[Brief explanation of the drawing]

Figures 1 (^), (B) and Figure 2 are cross-sectional views for explaining the composition of the composite material of the present invention, and Figure 3 shows an example of the composition of the second layer having a concentration gradient, as determined by Auger spectroscopy. This is a graph showing. Figure 1 (A) Figure 1 (B) Figure 2

Claims (5)

[Claims] (1) In a composite material having at least a boron nitride coating layer on the surface of the base material, as the first layer that may be in contact with the surface of the base material, one element selected from the group consisting of elements of group IVa, group Va, and group VIa. or has a metal film containing two or more types of elements, and as a second layer in contact with the first layer, a B film and/or a B-rich amorphous film with a B/N (atomic ratio) of 1.5 or more. 1. A boron nitride-coated composite material having a cubic boron nitride film in at least the outermost layer. (2) The boron nitride-coated composite material according to claim 1, wherein an intermetallic compound consisting of the metal and B is formed between the first layer and the second layer. (3) The boron nitride-coated composite material according to claim 1 or 2, wherein the first layer and the second layer are alternately laminated in large numbers. (4) The boron nitride-coated composite material according to claim (1) or (2), wherein the first layer, the second layer, and the cubic boron nitride film are laminated in large numbers alternately. (5) The boron nitride-coated composite according to any one of claims (1) to (4), which is heat-treated at a temperature of 600°C or higher in vacuum or in a nitrogen or argon atmosphere after forming the coating layer. material.