JPH02223437A - Polycrystalline diamond material and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture efficiently a polycrystalline diamond series substance, by a method wherein a coating layer of a metallic carbide or a metallic nitride is formed on the surface of the basic material by immersing the basic material into a molten salt both and a polycrystalline diamond layer is laminated onto the coating layer. CONSTITUTION:The basic material constituted of a metal containing carbon or an iron alloy or a diamond sintered body or ceramics is immersed into a molten salt bath and a coating layer of a metallic carbide or a metallic nitride is generated on the surface of the basic material. Then a polycrystalline diamond series substance is formed by laminating a polycrystalline diamond layer onto the coating layer. Concretely, a sintered diamond layer 3 is provided on the basic material through an intermediate layer 2 of the coating layer resulting from the foregoing immersing method. Although a soldering method is most simple for joining of the sintered layer 3, a high temperature and high pressure method performing along with also sintering is suitable from a strength point of view.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a polycrystalline diamond-based object and a method for producing the same, particularly a polycrystalline diamond-based object using a carbon-containing metal, a ceramic, and a substance consisting of carbon as a base material, or a metal nitride. A polycrystalline diamond-based object formed by using a base material as a base material, first providing a metal carbide film layer or a metal nitride wave film layer on the surface of the base material by a dipping method, and then providing a polycrystalline diamond layer on the second film layer. and its manufacturing method.

More specifically, 1 the present invention first forms a metal carbide coating layer or metal nitride coating layer on the surface of a base material using a molten salt bath, and then uses the coating layer as an intermediate layer to form a polycrystalline diamond layer or a diamond coating layer. The present invention relates to a polycrystalline diamond-based object having a grown carbon layer or a sintered diamond layer, and a method for producing the same.

Here, "polycrystalline diamond-based object" is.

The name also includes base materials in which a polycrystalline diamond layer, a diamond-like carbon layer growth layer, or a sintered diamond layer is present on the surface of the base material.

These are collectively called polycrystalline diamond-based objects. Such polycrystalline diamond-based objects can be used, for example, as cutting tools and wear-resistant tools.

(Prior Art) Since polycrystalline diamond does not have a cleavage ring in a specific direction, it has conventionally been used primarily as a cutting tool as a sintered diamond object to which several types of sintering aids have been added.

By the way, with the expansion of applications for sintered diamond objects,
Although larger sintered bodies have been required, it has been difficult to produce large sintered bodies due to equipment limitations. Furthermore,
Current sintered diamond bodies contain sintering aids such as N.
Since metals or alloys such as i, Fe, and Co are present in the grain boundaries, when used as a tool, the tool also has drawbacks such as deterioration of the tool due to heating.

It has also become known that due to its properties, diamond-coated cutting tools and wear-resistant tools made by growing polycrystalline diamond on, for example, cemented carbide by vapor phase synthesis are very useful. However, the adhesive strength between the polycrystalline diamond grown layer and the base material obtained by the conventional vapor phase synthesis method is currently insufficient for practical use.

In other words, when a polycrystalline diamond layer formed by vapor phase synthesis is made of a so-called non-oxide substrate such as SiC, WC, Tie, or Si3N4, it is relatively easy to generate diamond nuclei, and the growth of the nuclei is difficult. However, it is easier to obtain polycrystalline diamonds.

It is also known that diamond precipitation is difficult with common metals and metal oxides.

WC, Si, which is generally known as a superhard material,
WC sintered body in the vapor deposition of a polycrystalline diamond layer or a diamond-like carbon layer by a vapor phase synthesis method on a 3N4 sintered body.

Sintering aids Co, Ni for Si3N4 sintered body etc.

Since Fe, YO, A, j203, etc. inhibit the adhesion strength between the substrate and the diamond coating layer, or make it difficult to form a dense diamond coating layer, measures have been taken to eliminate the influence of the sintering aid. It's here (Japanese Unexamined Patent Publication No. 1983-
No. 100182, No. i3-45372.

H-14889, H-58-126972 and H-81-106478).

and a method by coating with metal carbide etQ (Japanese Patent Application Laid-open Nos. 58-128972 and 81-106478).
However, the bonding strength between the coating layer and the substrate was not sufficient.

(Problems to be Solved by the Invention) Two objects of the present invention are to solve the above-mentioned problems and provide a polycrystalline diamond-based object and a method for producing the same that are effective in expanding its uses.

A more specific object of the present invention is to provide a polycrystalline diamond-based object that is expected to have many expanded uses by forming a polycrystalline diamond layer or a diamond-like carbon layer at low cost and easily, and to facilitate mass production. The purpose is to provide an excellent manufacturing method.

In particular, diamond has excellent adhesion strength between the base material and the diamond layer through the intermediate layers of chromium carbide, vanadium carbide, titanium carbide, and titanium nitride, and diamond is easy to generate and grow, making it a characteristic of diamond as an ultra-hard material. The object of the present invention is to provide a polycrystalline diamond-based object useful as a cutting tool or a wear-resistant tool by taking advantage of the above characteristics, and a method for producing the same.

(Means for Solving the Problems) As a result of extensive research in view of the problems of the prior art, the present inventors have found that metal carbide or metal carbide that can easily be deposited on a base material to satisfy the bonding strength with the base material by the dipping method. A polycrystalline diamond-based object in which a metal nitride coating layer can be formed and a diamond layer can be easily laminated by laminating a polycrystalline diamond layer on this coating layer by a bonding method or a vapor phase growth method. It was experimentally confirmed that this can be obtained.

That is, a metal carbide or metal nitride coating layer obtained by the immersion method can be bonded with a sintered diamond layer to obtain an arbitrarily large polycrystalline diamond-based object, or a diamond layer or diamond layer can be formed by a vapor phase synthesis method. It is extremely effective as a substrate for easily generating and growing a carbon layer, and in particular, by vapor phase synthesis, it is possible to obtain a highly pure diamond laminate that does not contain any metal phase, which is disadvantageous when used as a tool. I know that.

The present invention has now been completed.

Although the immersion method itself has been known in the past, the purpose of the conventional method was to harden the surface and it was carried out as a final surface treatment. It was not intended at all.

The gist of the present invention is that the present invention is composed of a coating layer made of metal carbide or nitride provided on the surface of a base material by a dipping method, and a polycrystalline diamond layer laminated on this coating layer. It is a polycrystalline diamond-based object.

According to a preferred embodiment of the present invention, the base material may be carbon or a carbon-containing material or a metal nitride.

Further, the carbon-containing material is preferably selected from the group consisting of carbon-containing metals, iron alloys, diamond sintered bodies, monolithic diamonds, ceramics (eg, T i C, S i C), and metal carbides. Examples of carbon include graphite and carbon materials.

In addition, examples of the metal carbide or metal nitride constituting the coating layer as the intermediate layer include interstitial carbides and nitrides made of IVa to VIa group transition metals, such as titanium carbide, chromium carbide, vanadium carbide, chromium nitride, and titanium nitride. Can be mentioned.

In particular, chromium carbide (Cr C) or vanadium carbide (
VC), titanium carbide (T i C), titanium nitride (T
iN), the adhesive strength between the base material and the diamond layer does not drop suddenly even if the film thickness is increased. That is, by the dipping method, a strong and thick intermediate layer can be formed by diffusion of the metal elements of the base material and the intermediate coating, and the adhesion between the base material and the diamond layer through the intermediate layer is not reduced. The effect of increasing the thickness of this intermediate layer is due to the difference in thermal expansion between the diamond layer and the base material, and its effect as a layer that buffers the impact that the diamond layer receives. Since the metal elements in the intermediate layer are fine due to interdiffusion, it also helps to alleviate the discomfort between the diamond layer and the base material, which are different materials depending on the film thickness.

Its chromium carbide, vanadium carbide, titanium carbide.

The thickness of the titanium nitride coating layer is preferably 2, for example, 2 to 12 μm, particularly 5 to 12 μl. In that case, all of the above-mentioned materials can be used as the base material.

Another aspect of the present invention is to generate a coating layer of metal carbide or metal nitride on the surface of the base material by immersing the base material in a molten salt bath, and then to form a polycrystalline film on the surface of the base material. This is a method for producing a polycrystalline diamond-based object characterized by laminating diamond layers.

As already mentioned, the polycrystalline diamond layer may be a polycrystalline diamond layer or a diamond-like carbon layer grown by a vapor phase synthesis method, or a bonding layer of a polycrystalline diamond sintered body by a bonding method. There may be.

The above bonding method is preferably carried out by one method selected from the group consisting of a brazing method, a solid phase diffusion method, and a high temperature and high pressure method.

In addition, when a polycrystalline diamond layer or a diamond-like carbon layer is generated by a diamond vapor phase synthesis method, the specific mode is not particularly limited.9For example, an appropriately prepared raw material gas is supplied to an appropriate pressure. This may be carried out by precipitating polycrystalline diamond or diamond-like carbon for an appropriate period of time in a reaction tube.

The "immersion method" is generally a method in which the base material to be treated is immersed in an immersion bath, preferably a molten salt bath containing the metal constituting the intermediate layer, for an appropriate period of time to form a surface coating.

(effect) Next, the present invention will be further explained along with its effects.

FIG. 1 (1) is a cross-sectional view schematically showing a polycrystalline diamond-based object according to the present invention, in which an intermediate layer, which is a coating layer derived from the above-mentioned dipping method, is formed on a base material 1. A sintered diamond layer 3 is provided via 2. Brazing is the simplest method for joining this sintered layer, but in terms of joining strength, a high temperature and high pressure method that also performs sintering is preferred.

FIG. 1 (2) shows an example of a lamination method using the vapor growth method, in which a vapor growth diamond layer 4 is similarly provided on the base material 1 via an intermediate layer 2 also derived from the dipping method. ing.

The intermediate layer 2 is produced by a dipping method, and has extremely high adhesive strength not only to the surface of the base material but also to the laminated sintered layer and vapor-grown layer.

Therefore, the original strength and wear resistance of the sintered layer and the vapor-grown layer are fully exhibited.

The thickness of the intermediate layer 2 is not particularly limited, but is 0.1 to 30 μm.
About m is preferable. Further, there is no limit to the number of sintered layers to be laminated. The thickness of the vapor grown layer is preferably about 0.1 to 20 .mu.m. If it is too thick, it will not only be difficult to manufacture and expensive, but also easily peel off due to the stress generated inside the film. On the other hand, if it is too thin, the desired effect cannot be achieved.

Next, two methods of manufacturing the above-mentioned polycrystalline diamond-based object according to the present invention will be explained.

First, according to the present invention, the base material is subjected to a dipping treatment, and various materials can be used as the base material as long as metal carbide or metal nitride can be formed on the surface by the dipping method described later. Examples of these include carbon and carbon-containing substances or metal nitrides in the broadest sense, and more specifically carbon-containing metals, iron alloys, diamond sintered bodies, guyarmond monoliths, ceramics such as SiC or TiC,
These include graphite, carbon materials, and 513N4.

Incidentally, as the polycrystalline diamond layer, a sintered diamond layer or a layer precipitated by vapor phase synthesis is used, but in order to put this vapor phase synthesized diamond layer into practical use as a cutting tool, the adhesive strength between the substrate and the diamond layer must be is an important issue. Conventionally, WC, Tic, SiC, Si3N
It is known that the adhesion strength between non-oxide ceramics such as No. 4 and the diamond layer is very good. It does not have sufficient rigidity and hardness to support the diamond coating and is difficult to process into the shape of a tool.

Furthermore, when materials other than metal carbides and metal nitrides are used (2) For example, when St, Ti, W, etc. are used, scratches on the surface of the base material can be prevented by heat treatment after treatment and diamond layer coating.
It is necessary to increase the adhesive strength with the diamond layer by performing a process (Japanese Patent Application Laid-open No. Sho Ll-99102), but at this time, if the shape of the base material is complex, there may be difficulties in processing accuracy, etc. Heat deterioration occurred.

In addition, the conventional method of creating an intermediate layer between a base material and a polycrystalline diamond layer or a diamond-like carbon layer using a vapor phase synthesis method uses high-temperature CV as a coating method for the intermediate layer.
Since we use methods such as method, plasma CVD method, sputtering method, ion blating method, ion implantation method, etc., there is almost no reaction between the base material and the intermediate layer, so the adhesive strength is superior to that of cutting tools and wear-resistant tools. I could not say that I was fully satisfied.

Therefore, according to the present invention, by using the dipping method, various materials can be used as long as they are carbon-containing materials and metal nitrides, and furthermore, an intermediate layer of metal carbide or metal nitride can be provided on the surface of the base material. Therefore, not only the adhesive strength with the polycrystalline diamond layer or the diamond-like carbon layer obtained by vapor phase synthesis method is extremely excellent, but also the bonding strength between the base material and the intermediate layer is extremely excellent. . Furthermore, in general, the growth of a polycrystalline diamond film by vapor phase synthesis depends on the type of metal carbide or metal nitride of the base material. If there is a need.

Since two or more types of metal carbides and metal nitrides can easily coexist in the intermediate layer, it is possible to grow nine different types of polycrystalline diamond films.

Furthermore, if an intermediate layer such as CrC is used, the oxidation resistance of the base material is improved, so that even better effects can be obtained in terms of protecting the base material for applications that involve heat generation, such as cutting and wear-resistant tools.

In particular, if carbon steel is used as the base material for diamond tools, shape processing is very simple and can be done using conventional metal processing methods, so its applications can be greatly expanded. .

A typical example of the molten salt bath constituting the immersion bath used in the present invention is a molten halide bath. Other molten salt baths include carbonate phosphates, ferrates, aluminates, silicates, and borates. Although the salt bath is not particularly limited, a halide bath is preferred because it is easy to handle.

The type of metal that becomes the metal carbide or metal nitride is not particularly limited, but it is preferable to use one that has a high bonding strength with the diamond layer. For example, when using molten halide baths, some of these metals are added to the molten chloride bath as compounds, typically oxides, which are readily available and easy to handle. It is advantageous because it is. Moreover, another part may be added as a metal powder. In that case.

The metal may be added as an elemental metal or an alloy 1 containing the same, such as a ferroalloy.

Although there is no particular restriction on the amount of the metal element 1 alloy to be added, the amount of the metal oxide is preferably 5 to 7% by weight. If it is too small, a sufficient thickness will not be obtained as an intermediate layer, while if it is too large, the thickness of the intermediate layer will be non-uniform.

For example, when an oxide is used, 5 to 15 weight 26 of a reducing agent for reducing the oxide is added.

If the amount of the reducing agent is less than this, the reducing effect will be insufficient, whereas if it is too much, the formation of carbides and nitrides will be hindered. As the reducing agent, Mn, AJ2. Ca, SiTi, Zr, etc. or alloys thereof such as FeMn, Fe-AJ, Fe
-Ti, Fe-Zr.

Fe-5i, Ca-3t, Ca-8i-Mn, etc.

An element having a greater affinity for oxygen than chromium or a Group Va element is used.

Although it is not necessarily necessary to pre-treat the base material prior to the dipping treatment, adhesion to the intermediate layer can be improved by preferably degreasing or other treatment.

A polycrystalline diamond layer is laminated by bonding or vapor phase deposition (growth) on the intermediate layer of the carbide layer and nitride layer formed by such a dipping method. Since the diamond layer in this case is polycrystalline, it has no directionality and has high fracture strength.

This polycrystalline diamond layer can be formed by joining the sintered diamond bodies by any conventional method such as soldering, solid phase diffusion, high temperature and high pressure. Any conventional bonding method can be used.

Alternatively, if a polycrystalline diamond layer or a diamond-like carbon layer is deposited on the intermediate layer by diamond vapor phase synthesis, the thickness of the diamond layer is preferably from 0.5 to 20 μm.

If it is too thick, not only is there a cost problem, but also cracks may occur in a part of the diamond layer. If it is too thin, good grindability cannot be achieved. Although any method can be applied as such a vapor phase synthesis method, microwave plasma C
VD method is preferred.

This is because the reaction temperature is low and a polycrystalline diamond layer can be stably deposited. When the microwave plasma CVD method is adopted, a mixed gas of hydrocarbon and hydrogen (for example, a ratio of hydrocarbon: hydrogen - 1:100) is used as the supply gas.
may be used, and microwaves or high frequency waves may be used as the plasma generation wave. Pressure 10' ~ 7[10To
rr, the base material temperature is preferably 300 to 1300°C. As the hydrocarbon, methane, ethane, propane, butane, etc. are usually used.

Hereinafter, the present invention will be described in more detail with reference to examples thereof.

Example 1 Alloy tool steel SK S21 was used as the base material.

This is the shape of a tip for a bite (IOX IOX 5 m
m) (lapping and polishing in 2 μm diamond paste for 30 minutes), and then degreased. This chip was placed in a porcelain crucible containing 42.2 mol% of K Cf.
, B a Cj! 220.2 mol% and Na
Immersion was performed at 900° C. for 2 hours in an immersion bath consisting of 37.13 mol % F, TiO, and Fe-Ti. The thickness of the 110-layer coating formed as the intermediate layer at this time was 2.0
It was μm.

This TiC layer is used as an intermediate layer and a sintered diamond layer (IO
A polycrystalline diamond-based object was obtained by heat-bonding the materials (X 10

The chip obtained in this way was attached to a holder in a machine 9, and a cutting test was conducted under the test conditions of the usage example described below. It was found that extremely good processing was possible and it could withstand continuous use for a long time. there were.

Example 2 A TiC intermediate layer was formed on the surface of alloy tool steel S K S 21 in the same manner as in Example 1, and then subjected to microwave plasma CVD.
Diamond was deposited on the TiC layer of 1-alloy tool steel using a mixed gas of meta and hydrogen gas. The methane gas concentration at this time was 0.5% (volume). Plasma was generated in a quartz reaction tube using microwaves (2.45 GHz) and an output of 450 W, and deposition was performed for 24 hours. The reaction temperature was 830°C. After the reaction, a 5 μm polycrystalline diamond film was precipitated and a polycrystalline diamond-based object was obtained.

FIG. 2 shows an electron micrograph of the surface of this polycrystalline diamond-based object.

It can be seen that a polycrystalline diamond layer is stacked over the entire surface of the sample.

Next, similar experiments were conducted using Si3N4 ceramic, WCC raw carbon material, and diamond sintered body as the base materials, and similar results were obtained.

Example 3 A WC chip was used as the base material. This chip was degreased and then coated with a Cr--C layer by a dipping method. The coating thickness was 15.0 μm. A sintered diamond material is fitted to this Cr6 layer coated chip.

1. In a vacuum of OX 1O-3Torr, 100kg
Heating to 1200℃ for 1 hour under a compressive load of /-
A polycrystalline diamond-based object was obtained by interdiffusion of r-C and the diamond sintered body.

Example 4 According to Example 1, a 5 μm thick Cr-C intermediate layer was formed on the surface of a WC chip, and a mixed gas of methane and hydrogen gas was used by the microwave plasma CVD method.

Diamond was deposited on the Cr-C layer of the WC chip. The gas phase synthesis was carried out in the same manner as in Example 2. and 4μ
1 of polycrystalline diamond films were precipitated and a polycrystalline diamond-based object was obtained.

Example 5 As in Example 1, a TiN intermediate layer was formed on the surface of a 5isN4 ceramic chip, and a 5isN4
Diamond was deposited on the TiN layer of the ceramic chip. The gas phase synthesis was carried out in the same manner as in Example 2. Then, a polycrystalline diamond film of 4 μm was deposited to obtain a polycrystalline diamond-based object.

Example 6 Graphite was used as the base material. After degreasing, this graphite was placed in a porcelain crucible to yield K C] 42.2%, B a C, e
220.2 mol%, NaF 37.6 mol% and T t
The sample was immersed at 900° C. for 3 hours in an immersion bath containing equimolar amounts of O2, metal Ti, Cr2O3, and metal Cr.

Cr-C was formed as an intermediate layer at this time.

The coating thickness of the TiC coexistence layer was 3.0 μm. Then, diamond was deposited on the graphite forming the intermediate layer by microwave plasma CVD using a mixed gas of methane and hydrogen gas. The gas phase synthesis was carried out in the same manner as in Example 2. Then, a polycrystalline diamond film of 5 μm was deposited and a polycrystalline diamond-based object was obtained.

Example of use The coating bonding strength of the samples obtained in each of the above-mentioned Examples was evaluated by a scratch test under the following conditions. The results are summarized in the table below.

The results shown in Table 1 also show that the surface coating obtained by the present invention is particularly effective in fields where coating bonding strength is required, such as cutting tools and wear-resistant tools.

(Experimental conditions) Indenter: Diamond indenter.

Chip radius 0.2mm, 120℃ Scratch speed: 10mm/min Maximum load: 20kg1' Sample size: 20X20X10t (+nm)
Table 1: Scratch test results Adhesion strength (kg): Peeling load between base material (coating layer) and diamond layer.

As is clear from Table 1 above, the adhesion strength of the examples is as follows:
No intermediate layer (Comparative Example A).

B), and those with an intermediate layer formed by CVD method (
It is also extremely high compared to Comparative Example C).

Examples 7 to 15 The thickness of the intermediate layer was increased, and the adhesion strength and diamond generation/growth were further investigated.

An intermediate layer was formed in the same manner as in Example 1 to have a thickness of 8.0 μm or more. Note 1: For example, in the case of a CrC intermediate layer,
Cr2O3 and metal Cr (reducing agent) K Cj! , B
Using an immersion bath containing a C, e 2, etc.,
The same procedure was applied to other intermediate layer compositions (
containing a corresponding oxide and a metal as a reducing agent).

Then, it was subjected to a scratch test under the same conditions as above to examine the bonding strength. The results are shown in Table 2.

(Margin below) Table 2 Also, Table 2-2 shows the adhesion strength at the stage of forming the intermediate layer, that is, the peeling load (kg) between the base material and the intermediate layer, especially for CrC and VC TiC intermediate layers. ) is shown.

Table 2-2 Outside the scope of Kimoto's invention l) T i C coating layer is formed by CVD method.

Adhesion strength: Peeling load between the base material (coating layer) and the diamond layer.

Next, Example No. 7. 8.10.11.12.15
．． Using No. 1618 and Comparative Examples Nos. 2, 4, and 7, the generation and growth conditions of the diamond layer, that is, the generation density and growth rate of diamond nuclei, were investigated.

In this case, the nucleation density is an SEM photograph (X 5000 times)
The growth rate was calculated by visually counting the generated nuclei based on , and the growth rate was similarly measured by SEM observation from the side in the thickness direction (growth direction). The results are shown in Table 3.

Table 3 As is clear from Table 2, Table 2-2, and Table 3 above,
Even when the film thickness increases, the adhesion strength of Examples hardly decreases, and shows a higher value than those without an intermediate layer or even those with an intermediate layer formed by CVD. Furthermore, the diamond growth rate is extremely fast, about 2 to 5 times that of the comparative example.

In particular, chromium carbide, vanadium carbide,
When titanium carbide or titanium nitride is used, the effect becomes even more remarkable and is superior to those of other intermediate layer compositions according to the present invention. Therefore, interlayers formed by dipping methods, especially CrC, VC.

It has been found that the Tic and TiN intermediate layers are extremely superior in terms of strength and generation and growth of the diamond layer.

The performance of the samples obtained in each of the above-mentioned Examples was evaluated by a cutting test under the following conditions as a cutting tool. The results are summarized in Table 4 below.

(Cutting conditions) Work material: A (alloy (Aj!-8L alloy) Speed
: 800m/min Depth of cut: 5.0~IO, Omm Feed: 0.6mm/re
v Table 4 (Cutting Test Results) The results shown in Table 2 also show that the surface coating obtained by the present invention is particularly excellent in improving cutting performance.

(Effects of the Invention) As described above, according to the present invention, the wear resistance,
Polycrystalline diamond-based objects, which have been poured due to their characteristics such as hardness, can be bonded more firmly to the base material by using a metal carbide coating layer formed by a simple method called dipping as an intermediate layer. It becomes possible to join.

The polycrystalline diamond-based object thus obtained is particularly effective as a cutting tool 2, a wear-resistant tool, and the like. This immersion method is a simple process, and polycrystalline diamond-based objects can be obtained in arbitrary and large shapes. 2. The practicality of the present invention is high. Therefore, 1. The present invention contributes to the development of those skilled in the art. It's a big deal.

[Brief explanation of the drawing]

Figures 1 (1) and (2) are simple schematic cross-sectional views of polycrystalline diamond-based objects according to the present invention; and Figure 2 is a polycrystalline diamond obtained in Example 2 of the present invention. Surface state of a system object (crystal structure or particle structure)
This is a scanning electron micrograph (magnification: X 1000) showing. Ward

Claims (11)

[Claims] (1) A polycrystalline diamond-based object consisting of a coating layer made of metal carbide or metal nitride provided on the surface of a base material by a dipping method, and a polycrystalline diamond layer laminated on the coating layer. (2) The polycrystalline diamond-based object according to claim 1, wherein the base material is carbon, a carbon-containing substance, or a metal nitride. (3) The polycrystalline diamond-based object according to claim 2, wherein the carbon-containing material is selected from the group consisting of carbon-containing metals, iron alloys, diamond sintered bodies, monolithic diamonds, ceramics, and metal carbides. (4) The polycrystalline diamond-based object according to any one of claims 1 to 3, wherein the polycrystalline diamond layer is a polycrystalline diamond layer grown by a vapor phase synthesis method or a diamond-like carbon layer film grown. (5) The polycrystalline diamond-based object according to any one of claims 1 to 3, wherein the polycrystalline diamond layer is a bonding layer of a polycrystalline diamond sintered body by a bonding method. (6) Consists of a coating layer made of chromium carbide, vanadium carbide, titanium carbide, and titanium nitride provided on the surface of the base material by a dipping method, and a polycrystalline diamond layer deposited on top of this coating layer. Polycrystalline diamond-based object. (7) A film layer of metal carbide or metal nitride is generated on the surface of the base material by immersing the base material in a molten salt bath, and then a polycrystalline diamond layer is laminated on this film layer. A method for producing polycrystalline diamond-based objects. (8) The polycrystalline diamond system according to claim 7, wherein a polycrystalline diamond layer is laminated by forming a growth layer of a polycrystalline diamond layer or a diamond-like carbon layer on the coating layer by a vapor phase synthesis method. How to make an object. (9) The method for producing a polycrystalline diamond-based object according to claim 7, wherein a polycrystalline diamond layer is laminated by bonding a diamond sintered body onto the coating layer. (10) The diamond sintered body is joined by a brazing method,
10. The method for producing a polycrystalline diamond-based object according to claim 9, which is carried out by one method selected from the group consisting of a solid phase diffusion method and a high temperature and high pressure method. (11) A film layer of chromium carbide, vanadium carbide, titanium carbide, and titanium nitride is generated on the surface of the base material by immersing the base material in a molten salt bath, and then a polycrystalline diamond layer is formed on this film layer. A method for producing a polycrystalline diamond-based object characterized by laminating layers.