JP2002212764A - Peeling agent for ti-base film of sintered hard material surface, peeling method and regeneration treatment method for sintered hard material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress surface roughening by suppressing elution of Co in a sintered hard material and to shorten the time for peeling treatment of Ti-base films. SOLUTION: The peeling agent which contains hydrogen peroxide, an alkali hydroxide and aminocarboxylates and peels the Ti-base films formed on the surface of the sintered hard material contains 1 to 10 mass% at least one among tartrate, such as sodium tartrate and benzoate, such as sodium benzoate. This peeling agent surely peels and removes the Ti-base films formed on the surface of the sintered hard material while effectively suppressing the surface roughening by suppressing the elution of the Co in the sintered hard material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stripping agent and a stripping method for stripping and removing a Ti (titanium) -based coating formed on the surface of a cemented carbide, and to a super-hard coating having a Ti-based coating formed on the surface. The present invention relates to a method for regenerating a hard material.

[0002]

2. Description of the Related Art Carbide is made of WC (tungsten carbide) or carbides such as Ti, Ta (tantalum) and Nb (niobium) added as necessary, with a carbon content of about 3 to 30%.
An extremely hard material bonded with o (cobalt), used as a cutting tool, a wear-resistant tool, or a special structural material. In such a cemented carbide material, titanium and titanium nitride, in order to protect the cemented carbide base material from wear and scratches and improve the life,
T made of titanium compounds such as titanium carbide and titanium carbonitride
It is common to coat the base material surface with an i-based coating.

[0003] For example, in a cold forging die made of a super hard material, high precision is required, so that a PVD (Physical) which has little thermal influence on a base material due to a surface treatment.
Using a Vapor Deposition process,
The life of the mold is improved by forming a Ti-based coating on the surface of the mold.

[0004] On the other hand, super-hard materials are more expensive than iron-based materials and the like. For this reason, in the case of a cold forging die having a large size and a complicated shape, if the cold forging die is worn or damaged, a regeneration process is performed in order to reduce the die cost.

[0005] The regeneration process of the cold forging die itself is generally performed by polishing or grinding. However, when trying to grind or polish the cold forging die with the Ti-based film formed on the surface, the work becomes difficult due to the difficult-to-cut nature of the Ti-based film as a hard film, and the work efficiency decreases. At the same time, high-precision reproduction becomes difficult.

[0006]

Therefore, in order to polish or grind the cold forging die with high precision, it is necessary to peel and remove the old Ti-based coating.

[0007] At this time, even if an attempt is made to remove the Ti-based coating by grinding or the like, the work becomes difficult, especially in a cold forging die having a complicated shape, due to the difficulty of cutting the Ti-based coating as described above.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 6-228778, the immersion treatment using a chemical treatment liquid removes the Ti-based film even in a cold forging die having a complicated shape. Becomes easier. Incidentally, the chemical removing agent disclosed in this publication is an organic solvent mainly composed of a protic solvent,
It contains an alkali fluoride salt, an alkali phosphate salt, an alkali hyposulfite, a water-soluble polymer, a tannic acid or an unsaturated fatty acid, and a surfactant.

However, in the chemical conversion treatment using the above-mentioned conventional chemical treatment solution, there is a problem that Co in the cemented carbide elutes to cause surface roughness. Moreover, if the Ti-based coating is directly applied to the superhard material having the roughened surface, the surface accuracy is reduced. Therefore, when reusing the superhard material, the surface accuracy of the hard metal having the roughened surface is restored. Therefore, it is necessary to grind or grind the surface of the super hard material.

Furthermore, the chemical conversion treatment using the above-mentioned conventional chemical treatment liquid has a problem that a long treatment time of several tens of hours or more is required.

The present invention has been made in view of the above circumstances. (1) It is possible to suppress the elution of Co in a cemented carbide material, to effectively suppress surface roughness, and to reduce Ti as compared with the prior art.
To provide a release agent for a Ti-based coating on the surface of a cemented carbide material capable of shortening the time required for the release processing of a Ti-based coating. To provide a method for removing a Ti-based coating on the surface of a cemented carbide material, and (3) eliminating the need to re-polish and grind the surface of the cemented carbide after removing the Ti-based coating;
By shortening the time required for peeling off Ti-based coatings,
An object of the present invention is to provide a method for regenerating a cemented carbide material capable of simplifying a regenerating process and reducing a processing time.

[0012]

Means for Solving the Problems The stripper for the Ti-based coating of the superhard material of the present invention for solving the above-mentioned problem (1) contains hydrogen peroxide, alkali hydroxide and aminocarboxylate, A release agent for releasing a Ti-based film formed on a surface of a material, wherein the release agent contains at least one of a tartrate and a benzoate.

According to this release agent, the Ti-based coating formed on the surface of the cemented carbide can be reliably removed and removed while suppressing the elution of Co in the cemented carbide and effectively suppressing the surface roughness. it can. Moreover, when this release agent is used, 0.5 to 1.
The Ti-based film can be peeled and removed at a removal rate of 0 μm / hour, and the time required for the peeling treatment of the Ti-based film can be reduced as compared with the conventional case.

In a preferred embodiment, the content of at least one of the tartrate and the benzoate is 1 to 10 m
ass%.

In a preferred embodiment, the tartrate is potassium sodium tartrate.

In a preferred embodiment, the benzoate is sodium benzoate.

According to the method of the present invention for solving the above-mentioned problem (2), a method of removing a Ti-based coating on the surface of a cemented carbide material comprises immersing a cemented carbide material having a Ti-based coating on the surface in a release agent. The present invention is characterized in that the Ti-based film is peeled and removed at a removal rate of 0.5 to 1.0 μm / hour.

According to this peeling method, 0.5 to 1.0 μm
Since the Ti-based film is peeled and removed at a removal rate of m / hour, it is possible to shorten the time required for the peeling treatment of the Ti-based film as compared with the conventional case.

In a preferred embodiment, the release agent contains hydrogen peroxide, alkali hydroxide and aminocarboxylate, and further contains at least one of tartrate and benzoate. By using such a release agent, the processing time can be shortened as compared with the conventional method, and at the same time, it is formed on the surface of the cemented carbide material while suppressing the elution of Co in the cemented carbide and effectively suppressing the surface roughness. The removed Ti-based coating can be reliably removed and removed.

The method for regenerating a cemented carbide according to the present invention, which solves the above-mentioned problem (3), uses a T
A method for regenerating a cemented carbide with an i-based coating, wherein only the Ti-based coating formed on the surface is damaged and the surface of the cemented carbide on which the Ti-based coating is formed is undamaged. The cemented carbide material is immersed in a release agent containing hydrogen peroxide, alkali hydroxide and aminocarboxylate, and further containing at least one of tartrate and benzoate to form the Ti-based coating. And a film forming step of forming a new Ti-based coating on the surface of the cemented carbide material from which the Ti-based coating has been removed.

In this method for regenerating a cemented carbide, only the Ti-based coating formed on the surface is damaged, and the surface of the cemented carbide on which the Ti-based coating is formed is not damaged. Peeling and removing. In addition, by using the above-mentioned specific release agent, the elution of Co in the cemented carbide material is suppressed, and the surface roughness is effectively suppressed, and the Ti-based film formed on the cemented carbide material is reliably removed and removed. be able to. For this reason,
After removing the Ti-based coating, it becomes unnecessary to perform polishing, grinding, or the like on the surface of the cemented carbide material to recover damage, wear, or surface roughness of the cemented carbide surface, thereby simplifying the regeneration process. it can. Also, by using the above specific release agent,
Since the Ti-based film can be peeled and removed at a removal rate of 0.5 to 1.0 μm / hour, the time required for the peeling treatment of the Ti-based film can be reduced and the time required for the regeneration treatment can be reduced as compared with the conventional case. It becomes possible to plan.

In a preferred embodiment, the cemented carbide is a cold forged die. Cold forging dies are often large and complicated, and from the viewpoint of reducing the cost of the die, there is a particularly strong demand for improvement of the life of the die and simplification and efficiency of the regeneration process. By utilizing the method for reclaiming cemented carbide according to the present invention, it is possible to meet such a demand, and thus it is possible to effectively reduce the die cost.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The release agent according to the present invention described in claims 1 to 4 and 6 to 8 (hereinafter, simply referred to as “the release agent according to the present invention”) comprises hydrogen peroxide, alkali hydroxide and Contains amino carboxylate.

Hydrogen peroxide oxidizes the Ti-based film to form T
It is contained to forcibly form an oxide of i.
If the content of hydrogen peroxide is too large, there is no effect corresponding to the amount, and it is uneconomical. If the content is too small, the oxidation effect cannot be obtained. For this reason, the content of hydrogen peroxide is 3 to 80mass when a 35% solution of hydrogen peroxide is added.
It is preferably set to s%.

The alkali hydroxide is contained to oxidize the Ti-based film to prepare an environment in which the aminocarboxylate dissolves Ti by complex formation. If the content of the alkali hydroxide is too large, the dissolution of other organic acids and the like is inhibited, and if the content is too small, the Ti dissolution rate of the aminocarboxylate decreases. For this reason, the content of the alkali hydroxide is preferably set to 0.1 to 5 mass%.
As the alkali hydroxide, specifically, sodium hydroxide, potassium hydroxide, lithium hydroxide or the like can be used.

The aminocarboxylate is contained for dissolving Ti oxidized with hydrogen peroxide into a stripping solution by complex formation. If the content of the amino carboxylate is too large, the effect of adding the amino carboxylate will not be obtained, and if it is insoluble, the dissolution rate will decrease if it is too small. For this reason, the content of the aminocarboxylate is preferably 0.1 to 15% by mass. As the aminocarboxylate, specifically, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DT
PA), each sodium salt of triethylenetetramine hexaacetic acid and the like can be used.

Further, the release agent according to the present invention can contain a silicate if necessary from the viewpoint of obtaining the stability of hydrogen peroxide. If the content of the silicate is too large, unnecessary phenomena such as formation of a silicate gel occur, and if the content is too small, it does not contribute to the stability of hydrogen peroxide. For this reason, the content of the silicate is preferably set to 0.5 to 5 mass%. As the silicate, specifically, sodium orthosilicate, sodium metasilicate, or the like can be used.

The greatest feature of the release agent according to the present invention is that it contains at least one of tartrate and benzoate. By containing tartrate or benzoate, the elution of Co, which is a component of cemented carbide, is effectively suppressed,
The surface roughness of the cemented carbide can be effectively suppressed. In addition, by containing both the tartrate and the benzoate, the synergistic effect of the two can effectively suppress the surface roughness of the cemented carbide due to the elution of Co.

If the content of at least one of the tartrate and the benzoate is too large, the effect corresponding to the amount will not be obtained,
It is uneconomical, and if the amount is too small, the above effects cannot be sufficiently expected. Therefore, the content of at least one of the tartrate and the benzoate is preferably 1 to 10 mass%. Specific examples of the tartrate include potassium sodium tartrate, sodium tartrate and potassium tartrate. Also, as benzoate,
Specifically, sodium benzoate, potassium benzoate, or the like can be used.

According to the release agent of the present invention having the above-mentioned structure, the release agent formed on the surface of the super-hard material while effectively preventing the surface roughness of the super-hard material due to elution of Co as a component of the super-hard material. The Ti-based coating can be reliably peeled and removed.

Therefore, when the cemented carbide itself is worn or damaged, or when only the Ti-based coating is worn or damaged and the cemented carbide itself is not worn or damaged, the surface accuracy of the cemented carbide is maintained. At the same time, it is possible to reliably remove the Ti-based coating formed on the surface of the super hard material. Therefore, when a new Ti-based coating is resurfaced after the removal of the Ti-based coating, it is not necessary to polish or grind the surface of the cemented carbide to recover the surface roughness. In addition, when the release agent according to the present invention is used, the Ti-based film can be peeled and removed at a higher removal rate than in the past, so that the time required for the peeling treatment of the Ti-based film can be reduced as compared with the conventional case. It becomes possible.

In particular, with respect to a cemented carbide with a Ti-based coating in which only the Ti-based coating is worn and damaged and the cemented carbide itself is not worn and damaged, the wear and tear of the cemented carbide using the release agent according to the present invention is improved. If the damaged Ti-based coating is peeled off and removed, the Ti-based coating formed on the surface of the cemented carbide material is surely suppressed while suppressing the elution of Co in the cemented carbide material and effectively suppressing the surface roughness as described above. In addition, peeling and removal can be performed in a shorter time than in the conventional case. For this reason, it becomes possible to maintain the surface condition and surface accuracy of the cemented carbide itself close to those of a new product. Therefore, after removing the Ti-based coating, it is not necessary to polish or grind the surface of the cemented carbide material in order to recover damage, abrasion or surface roughness of the cemented carbide surface, thereby simplifying and shortening the regeneration process. And the service life of the cemented carbide can be prolonged.

That is, the present invention relates to a method for regenerating a cemented carbide material having a Ti-based coating on the surface, wherein only the Ti-based coating formed on the surface is damaged and the Ti-based coating is formed. A step of immersing a cemented carbide material with a Ti-based coating in which the surface of the cemented carbide material is intact in a release agent according to the present invention to remove and remove the Ti-based coating; According to the method for regenerating a super hard material, a step of forming a new Ti-based film on the surface of the super hard material from which the film is removed is sequentially performed. The processing can be simplified and shortened. In particular, by using such a regeneration processing method for a large-sized and complicated cold forging die, the die cost can be significantly reduced.

When removing and removing the Ti-based coating on the surface of the cemented carbide using the release agent according to the present invention, the liquid temperature must be 15 ° C.
To 20 ° C., and the removal time can be a time according to the film thickness.

[0035]

Embodiments of the present invention will be specifically described below.

Example 1 As shown in Table 1, a 35% solution of hydrogen peroxide solution: 20 mass% (hereinafter simply referred to as “%”)
Sodium hydroxide as alkali hydroxide: 3%, EDTA as aminocarboxylate: 10
%, Sodium orthosilicate as a silicate: 3%, potassium sodium tartrate as a tartrate: 3%, sodium benzoate as a benzoate: 4%, and water: balance Got ready.

On the other hand, a cemented carbide (WC: 90% and Co: 1)
A 2 μm-thick Ti-based (TiN) film is formed by ion plating on the surface of JIS V30 having a composition of 0%, manufactured by Tokai Alloy Co., Ltd., trade name “G3]. Sample No. 1 made of a superhard material with a coating was prepared.

Further, a cemented carbide material (WC: 85% and Co: 1)
A 2 μm-thick Ti-based (TiN) film is formed by ion plating on the surface of JIS V50 having a composition of 5% (trade name “G7” manufactured by Tokai Alloy Co., Ltd.). Sample No. consisting of a coated hard metal 2 was prepared.

The obtained sample No. 1 and No. 1 2
Was respectively immersed in the above-mentioned release agent under the conditions of a release agent temperature of 20 ° C. and an immersion time of 4 hours to peel and remove the Ti-based coating from the surface of the cemented carbide material. The removal rate at this time was 0.5 μm / hour.

(Example 2) As shown in Table 1, a 35% solution of hydrogen peroxide solution: 20%, sodium hydroxide: 3%,
A release agent having a composition of EDTA: 10%, sodium orthosilicate: 3%, potassium sodium tartrate: 3% and water: balance was prepared.

Sample No. 1 made of a cemented carbide material having a Ti-based coating as in Example 1 was used. 1 and No. 1 2 was immersed in the above-mentioned release agent under the same conditions as in Example 1 to peel and remove the Ti-based coating from the surface of the cemented carbide material. The removal rate at this time was 0.5 μm / hour.

Example 3 As shown in Table 1, a 35% solution of hydrogen peroxide solution: 20%, sodium hydroxide: 3%,
A release agent having a composition of EDTA: 10%, sodium orthosilicate: 3%, sodium benzoate: 4%, and water: balance was prepared.

Sample No. 1 made of a cemented carbide material with a Ti-based coating as in Example 1 was used. 1 and No. 1 2 was immersed in the above-mentioned release agent under the same conditions as in Example 1 to peel and remove the Ti-based coating from the surface of the cemented carbide material. The removal rate at this time was 0.5 μm / hour.

Comparative Example 1 As shown in Table 1, 35%
Hydrogen peroxide solution: 20%, sodium hydroxide: 1
%, EDTA: 5%, sodium orthosilicate: 4% and water:
A release agent for a conventional iron-based material having the balance of the composition was prepared.

Sample No. 1 made of the same super hard material with a Ti-based coating as in Example 1 was used. 1 and No. 1 2 was immersed in each of the above-mentioned release agents under the conditions of a release agent temperature of 20 ° C. and an immersion time of 4 hours to peel and remove the Ti-based coating from the surface of the cemented carbide material. The removal rate at this time is 0.5 μm
/ Hour.

[0046]

[Table 1]

(Evaluation) In Examples 1 to 3 and Comparative Example 1, the surface roughness on the surface of the cemented carbide after removing the Ti-based coating was evaluated. This evaluation was performed using a stylus electric measuring instrument.
According to the notation of IS B 0601, the center line average roughness (Ra), the maximum height (Rmax), the ten point average roughness (R)
z). Table 2 shows the results. Note that T
Table 2 also shows the evaluation results of the surface roughness of the new superhard materials (G3, G7) before forming the i-based coating.

[0048]

[Table 2]

As is clear from Table 2, the stripping agents of Examples 1 to 3 containing at least one of potassium sodium tartrate as a tartrate and sodium benzoate as a benzoate are tartrate and benzoate. The decrease in surface roughness of the surface of the cemented carbide material after the removal of the Ti-based coating was reduced to about half or less as compared with the release agent of Comparative Example 1 containing neither of the above.
In particular, with the release agent of Example 1 containing both the tartrate and the benzoate, the decrease in the surface roughness of the surface of the cemented carbide material after the removal of the Ti-based coating was significantly reduced due to the synergistic effect of both.

Example 4 A release agent similar to the release agent of Example 1 whose composition is shown in Table 1 was prepared.

On the other hand, a cemented carbide (WC: 88% and Co: 1)
A 2 μm-thick Ti-based (TiN) film is formed by ion plating on the surface of JIS V40 having a composition of 2% (trade name “G6”, manufactured by Tokai Alloy Co., Ltd.). Sample No. 3 made of a superhard material having a coating was prepared.

The obtained sample No. 3 was immersed in the release agent under the conditions of a release agent temperature of 20 ° C. and an immersion time of 4 hours to peel and remove the Ti-based coating from the surface of the cemented carbide material. The removal rate at this time was 0.5 μm / hour.

Comparative Example 2 A release agent similar to that of Comparative Example 1 was prepared.

Sample No. 4 made of a cemented carbide material with a Ti-based coating similar to that of Example 4 was used. 3 is the temperature of the release agent: 2
Under a condition of 0 ° C. and immersion time: 4 hours, the substrate was immersed in the release agent to peel off and remove the Ti-based coating from the surface of the cemented carbide.
The removal rate at this time was 0.5 μm / hour.

(Evaluation) In Example 4 and Comparative Example 2, the surface roughness on the surface of the cemented carbide after the removal of the Ti-based film was evaluated in the same manner as described above. Table 3 shows the results. Note that T
Table 3 also shows the results of the evaluation of the surface roughness of the new superhard material (G6) before forming the i-based coating.

[0056]

[Table 3]

Example 5 Carbide (WC: 75% and C
o: A cold forging die of a predetermined shape made of JIS V60 having a composition of 25% and manufactured by Sumitomo Electric Industries, Ltd., trade name "G8]) is prepared, and a film is formed on the surface of the die by an ion plating method. A 2 μm thick Ti-based (TiCN) film was formed, and a cold forging die made of a super hard material with a Ti-based film was manufactured.

Using this cold forging die, as shown in FIG. 1, a coarsely toothed part 10 having a tooth shape 1 of a predetermined shape was cold forged. The coarse tooth part 10 is a rough part with an outer helical gear.

The coarse material accuracy of the obtained tooth profile coarse part 10 was evaluated. This evaluation was performed at each measurement position of the A section, B section, and C section of the tooth profile 1 shown in FIG. 1, the tooth profile error inclination, the tooth trace error inclination, and the OBD on the L plane and the R plane of the tooth cross section 2 shown in FIG. (Overball Diameter) was performed by measuring the average value, the maximum value, and the minimum value with the number of samples: N = 5. The results are shown in FIGS. Note that the tooth profile error slope refers to the pressure angle error amount, the tooth lead error slope refers to the twist angle error amount, and the OBD refers to the distance between two balls when the ball is inserted into the opposing tooth space. Outer diameter.

Further, after the cold forging is repeated about 100 to 1000 times, the following regeneration processing is performed.
Repeated times. That is, a cold forging die in which only the Ti-based coating is damaged and the surface of the forging die on which the Ti-based coating is formed is intact, is subjected to the conditions of a release agent temperature of 20 ° C. and an immersion time of 4 hours. Then, the Ti-based film was immersed in the release agent of Example 1 to peel off and remove the Ti-based film from the mold surface. The removal rate at this time was 0.5 μm / hour. Thereafter, a new Ti-based coating was formed on the mold surface under the same conditions as above.

Each time the regenerating process was repeated, the accuracy of the coarse material of the cold-forged tooth profile coarse part 10 was evaluated in the same manner as described above. The results are also shown in FIGS.

The inclination of the tooth profile error shown in FIG.
Although an error of about m occurs, it is within the range of 20 μm, which is a standard for required quality, and has little effect.

The inclination of the tooth streak error shown in FIG.
Although an error of about μm occurs, this is within the range of 22 μm which is a standard for required quality, and has little influence.

The accuracy of the OBD shown in FIG. 5 was almost the same as that of the new work before the reproduction process, and was within the required quality standard of 0.07 μm.

Therefore, according to the regeneration treatment method of this embodiment, even if the regeneration treatment is repeated, the mold surface accuracy of the cold forging die can be favorably maintained without polishing or grinding the mold surface. It was confirmed that there was.

[0066]

As described above in detail, according to the release agent of the present invention, the Ti-based coating is reliably and rapidly removed while suppressing the surface roughness due to the elution of the super hard component, Co. It becomes possible.

In the state where only the Ti-based coating was damaged and the surface of the cemented carbide material on which the Ti-based coating was formed was not damaged,
If the Ti-based coating is peeled and removed with the release agent according to the present invention, high surface accuracy can be achieved even if a new Ti-based coating is re-surfaced without polishing and grinding the surface of the cemented carbide material. Can be maintained.

Therefore, it is possible to extend the life of the super hard material and to simplify and shorten the regeneration process.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a coarse tooth part according to a fifth embodiment.

FIG. 2 is a partial perspective view showing a tooth cross-sectional shape of the coarse tooth part according to the fifth embodiment.

FIG. 3 is a diagram showing an evaluation result of a tooth profile error slope of a tooth profile coarse part according to the fifth embodiment.

FIG. 4 is a diagram showing an evaluation result of a tooth lead difference inclination of a coarse tooth part according to the fifth embodiment.

FIG. 5 is a diagram showing an OBD evaluation result of a coarse tooth part according to Example 5.

[Explanation of symbols]

 10: Tooth coarse part 1: Tooth profile

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Minoru Shinoda 50 Nodacho, Kariya-shi, Aichi Prefecture Inside Yuken Kogyo Co., Ltd. (72) Inventor Ikuyuki Isobe 50 Nodacho, Kariya-shi, Aichi 50 4K057 WA20 WB01 WB20 WE11 WE15 WE21 WE25 WF01 WF06 WF10 WG01 WN10

Claims (8)

[Claims] 1. A release agent containing hydrogen peroxide, an alkali hydroxide and an aminocarboxylate, for releasing a Ti-based film formed on the surface of a cemented carbide, comprising: a tartaric acid salt and a benzoate salt. A stripping agent for a Ti-based coating on the surface of a cemented carbide, comprising at least one kind. 2. The release agent for a Ti-based coating on the surface of a cemented carbide according to claim 1, wherein the content of at least one of the tartrate and the benzoate is 1 to 10 mass%. 3. The release agent for a Ti-based coating on the surface of a cemented carbide according to claim 1, wherein the tartrate is potassium sodium tartrate. 4. The release agent for a Ti-based film on a surface of a cemented carbide according to claim 1, wherein the benzoate is sodium benzoate. 5. A cemented carbide material having a Ti-based film formed on its surface is immersed in a release agent so that the Ti-based film has a thickness of 0.5 to 1.0 μm.
A method for removing a Ti-based film on a surface of a cemented carbide material, wherein the method removes and removes at a removal rate of m / hour. 6. The method according to claim 5, wherein the release agent comprises hydrogen peroxide, an alkali hydroxide and an aminocarboxylate, and further comprises at least one of a tartrate and a benzoate. A method for removing a Ti-based coating on the surface of a hard material. 7. A method for regenerating a cemented carbide with a Ti-based coating having a Ti-based coating formed on the surface, wherein only the Ti-based coating formed on the surface is damaged, and the Ti-based coating is formed. The surface of the cemented carbide material is a cemented carbide material with a Ti-based coating in an intact state, containing hydrogen peroxide, alkali hydroxide and aminocarboxylate, and at least one of tartrate and benzoate. A removing step of immersing in a release agent containing, removing and removing the Ti-based coating; and a coating forming step of forming a new Ti-based coating on the surface of the cemented carbide from which the Ti-based coating has been removed. A method for regenerating a superhard material, comprising: 8. The method of claim 7, wherein the cemented carbide is a cold forged die.