WO2011013766A1

WO2011013766A1 - Method for removal of hard coating film in superhard material, and method for production of superhard material

Info

Publication number: WO2011013766A1
Application number: PCT/JP2010/062835
Authority: WO
Inventors: 誠石川; 大助西尾; 毅沢井; 仁八代
Original assignee: 株式会社新菱
Priority date: 2009-07-31
Filing date: 2010-07-29
Publication date: 2011-02-03
Also published as: JP5540320B2; JP2011179108A; TW201120249A

Abstract

Disclosed is a method for removing a hard coating film in a superhard material, which can selectively remove a hard coating film provided on the surface of a superhard material such as a superhard tool and a mold, and can minimize the deterioration in a superhard base material. Specifically disclosed is a method for removing a hard coating film in a superhard material in which the surface of a superhard base material is coated with the hard coating film, wherein the superhard base material is produced by sintering superhard alloy particles each comprising a carbide of at least one element selected from the group consisting of Group-4 elements, Group-5 elements and Group-6 elements with a binder metal comprising at least one element selected from the group consisting of Fe, Co, Cu and Ni or an alloy containing any one element selected from the preceding group, and wherein the hard coating film comprises a nitride, a carbide, a carbonitride, an oxide or a boride of at least one element selected from the group consisting of Group-4 elements, Group-5 elements, Group-6 elements, Group-13 elements and Group-14 elements (excluding carbon). The method comprises bringing the superhard material into contact with an alkaline solution at a temperature ranging from 100 to 250°C inclusive.

Description

Method of removing hard film in cemented carbide material and method of producing cemented carbide material

The present invention relates to a method of removing a hard coating on a cemented carbide material and a method of manufacturing a cemented carbide material. More specifically, in the case of cemented carbide materials such as cemented carbide tools or molds having a hard coating formed on the surface, the nonstandard products at the time of production of these or hard products of use deterioration using these for cutting etc. The present invention relates to a chemical solution for removing a film, a method for removing a hard film using the chemical solution, and a method for producing a hard material for forming a hard film again on a hard material from which the hard film has been removed.

Cemented carbide is a cemented carbide tool in which a hard coating such as nitride is formed on the surface of a cemented carbide base material using CVD (chemical vapor deposition) or PVD (physical vapor deposition). Class or mold class. Since cemented carbides are excellent in properties such as hardness, toughness, and wear resistance, they are used in fields such as various cuttings and molds where these properties are required.

The cemented carbide base material is obtained by sintering cemented carbide particles such as WC (tungsten carbide) with a binder metal such as Fe, Co, Ni, and Cu at around 1500 ° C., and has a very high hardness and It has toughness. Since the base material of cemented carbide changes the characteristics such as hardness and toughness by changing the particle size of cemented carbide particles and the amount of binder metal, it is necessary to use metalworking tools, dies, etc. A suitable one is used. Generally, the smaller the particle size of cemented carbide particles or the smaller the amount of binder metal, the higher the hardness of the cemented carbide base material tends to be.

A hard coating is a coating made of a hard material formed on the surface of a base material using a CVD method or a PVD method for the purpose of further improving the wear resistance and corrosion resistance of the base material, and a carbide tool It contributes to the improvement of the life of the mold or mold. The compounds used for the hard coating include nitrides such as TiN, CrN, VN, TiAlN, AlCrN, TiAlCrN, TiSiN, carbides such as TiC, CrC, VC, etc. and carbonitrides such as TiCN. Is coated in a single layer or multiple layers.

By the way, carbide materials are “non-standard products” that have coating defects in the coating process of hard coatings at the time of their manufacture, and “defective products” that cause partial peeling and wear resistance defects etc. in a short time when using them. Furthermore, the hard coating wears out in normal long-term use, and the "life-deteriorated product" which has reached the life is generated. Such “non-standard products”, “defective products” and “life-deteriorated products” are mostly crushed from the viewpoint of resource protection, recovered as rare metal tungsten as WC powder and recycled and used. is there.
However, the current recycling methods involve many processes such as crushing, classification, re-sintering, shape processing and recovery, and there is a problem that recycling costs increase.

On the other hand, a reuse method of recoating a hard coating by removing a defective, defective or life-degraded hard coating from a cemented carbide base material is also advantageous in terms of efficiency and cost. Therefore, attempts have been made to remove hard coatings using various removal chemicals.
As a method of removing a hard film using a chemical solution in the prior art, a method using an acid-based chemical solution and a method using an alkaline chemical solution containing hydrogen peroxide are known.
As an example of a method using an acid-based chemical solution, Patent Document 1 discloses that the stainless steel on which the coating is formed is added to 70 ° C. or more by a method of removing the TiN coating coated on the surface of stainless steel. A method of immersion in a warmed 15-30 volume% nitric acid aqueous solution is disclosed. Further, as an example of a method using an alkaline chemical solution containing hydrogen peroxide, Patent Document 2 contains 1 to 60% by weight of hydrogen peroxide and 0.05 to 5% by weight of a surfactant, and There is disclosed a method of immersing a member to be subjected to film removal in an alkaline aqueous solution having a pH of 7.5 to 12.

JP-A-59-41479 JP 2005-48248 A

However, in the case of an acid-based chemical solution, although the hard film is removed, the binder metal is dissolved from the surface layer of the cemented carbide base material, and the surface layer of the cemented carbide base material becomes brittle. And since a base material will be damaged as soon as a recycled product which recoated the hard film on this is cut etc., there is a problem that endurance is insufficient.
Further, in a chemical solution containing hydrogen peroxide, hydrogen peroxide directly corrodes cemented carbide particles such as WC, so the strength of the base material is similarly lowered, and the durability in the case of a recycled product is not good. It is enough.

As described above, with the conventional method for removing a hard film using a chemical solution, it is the present situation that the technology has not been completed which satisfies both "selective removal of hard film" and "prevention of deterioration of cemented carbide base material". It was not necessarily appropriate for industrial implementation.

Under such circumstances, it is an object of the present invention to selectively remove hard coatings on the surface of cemented carbide materials such as cemented carbide tools or molds, and to minimize deterioration of the cemented carbide base material. It is an object of the present invention to provide a method of removing a hard film in a cemented carbide material, which makes it possible to

MEANS TO SOLVE THE PROBLEM As a result of repeating earnest research so that the said subject might be solved, the present inventors discovered that the following invention met the said objective, and came to this invention.

That is, the present invention relates to the following inventions.
<1> A group in which cemented carbide particles containing a carbide of at least one element selected from the group consisting of a group 4 element, a group 5 element and a group 6 element consist of Fe, Co, Cu and Ni The surface of a cemented carbide base material sintered with a binder metal consisting of at least one element selected from the group consisting of at least one element selected from these elements or an alloy containing these elements is a group 4 element, a group 5 element, a group 6 element, a group Coated with a hard film containing a nitride, carbide, carbonitride, oxide or boride of at least one element selected from the group consisting of Group 13 elements and Group 14 elements (with the exception of carbon) A method of removing the hard coating on the resulting cemented carbide material,
A method of removing a hard film on a cemented carbide, comprising bringing the cemented carbide into contact with an alkaline chemical solution at a temperature of 100 ° C. or more and 250 ° C. or less.
<2> The method for removing a hard film according to <1>, wherein the alkaline chemical solution contains a corrosion inhibitor of a cemented carbide base material.
<3> The corrosion inhibitor is at least one selected from the group consisting of Group 4 elements, Group 5 elements, Group 6 elements, Fe, Co, Cu and Ni constituting the cemented carbide base material. The method for removing a hard film according to <1> or <2>, which is a simple substance consisting of at least one element selected from the group consisting of elements or a compound containing the element.
The removal method of the hard film the said <3> description whose <4> above-mentioned corrosion inhibitor is a cobalt compound.
<5> The method for removing a hard film according to <4>, wherein the corrosion inhibitor is cobalt tungstate, cobalt hydroxide or cobalt oxide, or cobalt metal.
The removal method of the hard film as described in said <2> whose <6> above-mentioned corrosion inhibitor is a reducing agent.
The removal method of the hard film the said <6> description whose <7> above-mentioned reducing agent is a compound shown by following General formula (1).

(Wherein, R ₁ is any of a carboxyl group, an alkyl group having 1 to 6 carbon atoms, an acyl group and an alkoxycarbonyl group, and R ₂ is any of an alkyl group having 1 to 6 carbon atoms, an alkoxy group and a hydroxyl group And R ₁ and R ₂ may form a ring structure, and X ₁ and X ₂ each independently represent a hydrogen atom or an alkali metal.
<8> The method for removing a hard film according to <7>, wherein the reducing agent is dihydroxymaleic acid.
The removal method of the hard film the said <7> description whose <9> said reducing agent is a compound shown by following General formula (2).

(Wherein, R ₃ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, an alkenyl group, an alkynyl group, an acyl group, an alkoxycarbonyl group, n is 0 or 1 and X ₃ and X ₄ are each independently hydrogen Is either an atom or an alkali metal.)
<10> The method for removing a hard film according to <9>, wherein the reducing agent is at least one selected from ascorbic acid, sodium ascorbate, erythorbic acid and sodium erythorbate.
<11> The method for removing a hard film according to <6>, wherein the reducing agent is a compound represented by the following general formula (3-a) or (3-b) and / or a salt thereof.

(In the formulas (3-a) and (3-b), R ₄ is a carboxyl group, an aldehyde group, an alkoxy group, an alkoxycarbonyl group, or an acyl group, and R ₅ is a hydrogen atom or a hydroxyl group.)

<12> The method according to <11>, wherein the reducing agent is at least one selected from gallic acid, m-galoyl gallic acid, catechol and hydroquinone.
<13> The method for removing a hard film according to <6>, wherein the reducing agent is a monosaccharide, a disaccharide, a trisaccharide, a tetrasaccharide, an oligosaccharide, or a polysaccharide.
<14> The reducing agent is dihydroxyacetone, erythrulose, erythrose, xylulose, ribose, arabinose, xylose, deoxyribose, psicose, glucose, fructose, sorbose, tagatose, mannose, idose, talose, fucose, rhamnose, maltose, lactose, At least selected from sucrose, trehalose, tulanose, cellobiose, raffinose, maltotriose, acarbose, stachyose, galactose, ribose, fructooligosaccharide, galactooligosaccharide, mannanoligosaccharide, glycogen, starch, cellulose, dextrin, glucan, levan and inulin The removal method of the hard film of the said <13> description which is 1 type.
<15> The method for removing a hard film according to <6>, wherein the reducing agent is a phosphorus-containing reducing agent or a sulfur-containing reducing agent.
<16> The method according to <15>, wherein the reducing agent is disodium hydrogen phosphite or sodium thiosulfate.
<17> The method for removing a hard film according to <2>, wherein the corrosion inhibitor is at least one compound selected from the group consisting of an azole compound or a salt thereof, a thiourea compound and an acetylenic compound.
<18> The method for removing a hard film according to <17>, wherein the azole compound is benzotriazole.
<19> The method for removing a hard film according to <17>, wherein the thiourea compound is thiourea.
<20> The hard coating according to <17>, wherein the acetylene compound is at least one selected from 2-propyn-1-ol, 1-hex-3-ol, and 3-butyn-1-ol. How to remove
<21> The cemented carbide particle according to any one of the above <1> to <20>, wherein the cemented carbide particles contain a carbide of at least one element selected from the group consisting of W, Ti, Nb, Ta, V, and Cr. How to remove hard coatings.

<22> The method for removing a hard film according to any one of <1> to <21>, wherein the binder metal contains Co.
<23> The hard film comprises a nitride, carbide or carbonitride of at least one element selected from the group consisting of Ti, V, Cr, Si and Al. The removal method of the hard film in any one of <22>.
<24> Any one of the above <1> to <23>, wherein the hard coating contains at least one compound selected from the group consisting of TiN, TiAlN, TiSiN, TiAlCrN, CrN, TiCrN, VN, TiC and TiCN. Hard coating removal method described in.
<25> The method for removing a hard film according to any one of <1> to <24>, wherein the hard film is composed of a single layer or a multilayer film.
<26> alkaline chemical is, 1 ~ 20 mol / L ^- according to any one of <1> to <25> containing an alkali metal hydroxide and / or alkaline earth metal hydroxide (OH equivalent) Hard coating removal method.
<27> The method for removing a hard film as described in the above <26>, wherein the alkaline chemical solution contains 1 to 20 mol / L (OH ^- converted) sodium hydroxide and / or potassium hydroxide.
<28> The above-mentioned <1> for removing the hard film from the cemented carbide in an airtight processing container in which the gas phase part is replaced with an inert gas and / or a reducing gas and / or a vapor generated from an alkaline chemical solution. <27> The method for removing a hard film according to any one of <27>.
<29> A method for producing a cemented carbide-coated material coated with a hard coating, wherein the hard coating is removed by the method for removing a hard coating according to any one of <1> to <28>, and the hard coating is formed again.

The present invention selectively removes the hard coating on the surface of the cemented carbide while minimizing the surface deterioration of the cemented carbide in the cemented carbide material such as cemented carbide tools or dies. Because of this, efficient and inexpensive reuse of cemented carbide can be realized.

It is a surface SEM image of Example 1 (darkness at the center right is burnt by electron beam and not damage by film removal treatment). It is a surface SEM image of Example 2 (darkness on the center right is burnt by electron beam and not damage by film removal treatment). 7 is a surface SEM image of Example 3. It is a surface SEM image of Example 4 (darkness in the center right is burnt by electron beam and not damage by film removal treatment). 7 is a surface SEM image of Example 5. 7 is a surface SEM image of Comparative Example 1; 7 is a surface SEM image of Comparative Example 2; 7 is a surface SEM image of Comparative Example 3; 7 is a surface SEM image of Example 6. 7 is a surface SEM image of Example 7. 21 is a surface SEM image of Example 8. 21 is a surface SEM image of Example 9. 21 is a surface SEM image of Example 10. 7 is a surface SEM image of Comparative Example 4; 7 is a surface SEM image of Comparative Example 5; 21 is a surface SEM image of Example 11. 21 is a surface SEM image of Example 12. 21 is a surface SEM image of Example 13. 21 is a surface SEM image of Example 14. 21 is a surface SEM image of Example 15. It is a surface SEM image of Example 16. (The darkening at the center right is burnt by electron beam, not damage by film removal treatment). 21 is a surface SEM image of Example 17. 21 is a surface SEM image of Example 18. 21 is a surface SEM image of Example 19. It is a cross-sectional analysis result (the left figure is a SEM image and the right figure is a cobalt mapping image by EDX) of Example 7. FIG. It is a cross-sectional analysis result (the left figure is a SEM image and the right figure is a cobalt mapping image by EDX) of Example 9. FIG. It is a cross-sectional analysis result (the left figure is a SEM image and the right figure is a cobalt mapping image by EDX) of Example 10. FIG. It is a cross-sectional analysis result (the left figure is a SEM image and the right figure is a cobalt mapping image by EDX) of Example 11. FIG. It is a cross-sectional analysis result (the left figure is a SEM image and the right figure is a cobalt mapping image by EDX) of Example 15. FIG. It is a cross-sectional analysis result (the left figure is a SEM image and the right figure is a cobalt mapping image by EDX) of Example 16. FIG. It is a cross-sectional analysis result (the left figure is a SEM image and the right figure is a cobalt mapping image by EDX) of Example 18. FIG. It is a cross-sectional analysis result (the left figure is a SEM image and the right figure is a cobalt mapping image by EDX) of Example 19. FIG. It is a cross-sectional analysis result (the left figure is a SEM image and the right figure is a cobalt mapping image by EDX) of Comparative Example 4. It is a cross-sectional analysis result (the left figure is a SEM image and the right figure is a cobalt mapping image by EDX) of Comparative Example 5. It is a surface SEM image of the tip (non-abrasive side) before coat coating. It is a surface SEM image of the tip (abrasive surface) before coating coating.

In the present invention, cemented carbide particles containing carbide of at least one element selected from the group consisting of Group 4 elements, Group 5 elements and Group 6 elements consist of Fe, Co, Cu and Ni. A surface of a cemented carbide base material sintered with a binder metal consisting of at least one element selected from the group or an alloy containing these elements is a group 4 element, a group 5 element, a group 6 element, A hard film containing a nitride, carbide, carbonitride, oxide or boride of at least one element selected from the group consisting of Group 13 elements and Group 14 elements (with the exception of carbon). A method for removing a hard film on a coated hard material, comprising the step of bringing the hard material into contact with an alkaline chemical solution at a temperature of 100 to 250 ° C. It is referred to as “method”.
In the present invention, the group 4 element, the group 5 element and the group 6 element respectively mean elements belonging to the group 4 group 5 group 6 of the long period periodic table.

The feature of the method of the present invention is that the cemented carbide is brought into contact with an alkaline chemical solution (hereinafter sometimes referred to as "the chemical solution of the present invention") at a temperature of 100 to 250 ° C, preferably 170 to 220 ° C. It is. By using the chemical solution of the present invention and treating it in the above temperature range, it is possible to minimize the surface deterioration of the cemented carbide base material and at the same time to selectively remove the hard film. If the temperature of contact is too low, removal of the hard coating will be insufficient, and if the temperature of contact is too high, special facilities such as heating equipment and processing containers are often required, resulting in high processing costs. The problem arises.

Hereinafter, the present invention will be described in detail.
First, a cemented carbide to be subjected to the method of the present invention will be described.
A cemented carbide is a cemented carbide tool or die having a hard coating formed on the surface of a cemented carbide base material formed by sintering cemented carbide particles using a binder metal.

The cemented carbide particles serving as a base material of cemented carbide are composed of a Group 4 element such as Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, etc., a Group 5 element and a Group 6 element. Carbides of at least one element selected from the group can be mentioned, and these carbides can be used alone or in combination of two or more.
Among these, in particular, carbides of at least one element selected from the group consisting of W, Ti, Nb, Ta, V, and Cr are preferable, and WC is particularly preferable in that it has high strength. . In addition, in order to use WC as cemented carbide particles, other elements may be added to improve performance. Examples of the additive element include Ti, Ta, Nb, and the like for improving heat resistance. In the cemented carbide particles, the chemical formula represents a constituent element, and the stoichiometric ratio of the chemical formula is not particularly limited.
The particle size of the cemented carbide particles is not particularly limited, but is usually about 0.1 to 20 μm.

The binder metal is at least one element selected from the group consisting of Fe, Co, Cu and Ni, or an alloy containing these elements, which binds cemented carbide particles. Among these, it is particularly preferable to contain Co.
Further, from the viewpoint of increasing the toughness of the superhard material, Co alone or an alloy containing Co as a main component is suitably used as a binder metal because it is excellent in toughness. In the present invention, “an alloy containing Co as a main component” means an alloy containing 80 mol% or more of Co.
In addition, in order to change properties such as hardness and toughness of the cemented carbide material, elements other than the above metal elements may be contained in the binder metal.

The hard coating is formed on the surface of the cemented carbide base material using the CVD method or the PVD method. The material of the hard film is at least one element selected from the group consisting of Group 4 elements, Group 5 elements, Group 6 elements, Group 13 elements and Group 14 elements (with the exception of carbon). Mainly composed of nitrides, carbides, carbonitrides, oxides or borides.
Specifically, nitrides such as TiN, CrN, VN, TiAlN, AlCrN, TiAlCrN, TiSiN, carbides such as TiC, CrC, VC, BC, carbonitrides such as TiCN, oxides such as TiO, AlO, ZrO, etc. And borides such as CrB. The hard coating is formed by covering a thin film containing these compounds in a single layer or multiple layers.
Among these, the hard coating contains at least one selected from the group consisting of nitride, carbide or carbonitride of at least one element selected from the group consisting of Ti, V, Cr, Si and Al. In particular, at least one compound selected from the group consisting of TiN, TiAlN, TiSiN, TiAlCrN, CrN, TiCrN, VN, TiC and TiCN is preferable. When the hard coating contains these compounds, it can be easily removed by the chemical solution of the present invention.
In the present invention, in the above nitrides, carbides, carbonitrides, oxides and borides, the chemical formulas indicate constituent elements, and the stoichiometric ratio of the chemical formulas is not particularly limited.

Next, the chemical solution (alkali chemical solution) of the present invention will be described.
The drug solution of the present invention is an alkaline aqueous solution having a pH of 7 or more. In the chemical solution of the present invention, adjustment of pH may be performed by any method such as dissolution of ammonia, addition of hydroxide, etc., but alkali hydroxide, ie, alkali metal hydroxide such as Li, Na, K, Rb, etc. It is preferable to carry out by containing single or multiple types of alkaline earth metal hydroxides such as Be, Mg, Ca, Sr, and Ba. Among these, sodium hydroxide and potassium hydroxide are preferably used because of their solubility in water and relatively low cost.
The hard coating can be efficiently removed by using an aqueous solution containing these hydroxides in a concentration range of preferably 1 to 20 mol / L (OH ^- equivalent), particularly preferably 5 to 15 mol / L.
In addition to water, a water-soluble organic solvent such as alcohol may be contained as a solvent as long as the effects of the present invention are not impaired.

The chemical solution of the present invention preferably contains a corrosion inhibitor for the purpose of further suppressing partial corrosion of the surface layer of the cemented carbide base material.

When the chemical solution of the present invention containing a corrosion inhibitor is brought into contact with a cemented carbide, the corrosion inhibitor adsorbed on the surface of the cemented carbide base material, or the reaction between the binder metal of the cemented carbide base material and the corrosion inhibitor The surface compound thus formed suppresses corrosion such as oxidation of cemented carbide particles such as WC of cemented carbide and binder metals such as Co by alkali chemicals, or reduces the corrosion rate to cause corrosion and deterioration of cemented carbide. Can be suppressed.

As such a corrosion inhibitor,
Corrosion inhibitor (a): A corrosion inhibitor that suppresses corrosion by previously containing chemical species generated by dissolution of cemented carbide base metal in an alkaline chemical solution,
Corrosion inhibitor (b): A corrosion inhibitor capable of reducing an oxidizing agent such as dissolved oxygen in an alkaline chemical solution and suppressing corrosion by preventing oxidation of a cemented carbide base material,
Corrosion inhibitor (c): A corrosion inhibitor that forms a protective film on the surface of the base metal and suppresses corrosion
Can be mentioned.
These corrosion inhibitors may be used by simultaneously containing a plurality of types in an alkaline chemical solution, and the chemical solution of the present invention may contain a plurality of appropriate corrosion inhibitors to suppress corrosion of the cemented carbide base material. In some cases, the effect can be improved.
The corrosion inhibitors (a), (b) and (c) will be described in detail below.

"Corrosion inhibitor (a)"
The corrosion inhibitor (a) contains in advance in the chemical solution chemical species generated by dissolution of a base metal (a cemented carbide particle and a metal element in a binder metal) constituting a cemented carbide base material by being added to the chemical solution. By doing this, it is intended to suppress corrosion and elution.
The corrosion inhibitor (a) is at least one element selected from the group consisting of Group 4 elements, Group 5 elements, Group 6 elements, Fe, Co, Cu and Ni, which constitute the above-mentioned cemented carbide base material. Or a compound containing the element, and is appropriately selected depending on the base metal and / or the binder metal in the cemented carbide base material to be used. In addition, a corrosion inhibitor (a) may be made to contain multiple types simultaneously in the chemical | medical solution of this invention.
Since the corrosion of the superhard material by the alkaline chemical solution is mainly caused by the corrosion of the binder metal, the chemical solution of the present invention is a group consisting of Fe, Co, Cu and Ni constituting the binder metal as a corrosion inhibitor (a) It is preferable to contain a single metal containing at least one selected element or a compound containing the element.
Particularly in the case of a cemented carbide base material using an alloy containing Co suitable as a binder metal, the chemical solution of the present invention preferably contains a cobalt compound as a corrosion inhibitor (a).
As such cobalt compounds, cobalt tungstate, cobalt hydroxide, cobalt oxide and the like can be mentioned. Among these, cobalt tungstate and cobalt hydroxide are preferable, and cobalt tungstate is particularly preferable.
For example, in the case of a cemented carbide base material using WC as cemented carbide particles and an alloy containing Co as a binder metal, cobalt metal, tungsten metal, cobalt oxide, tungsten oxide as a corrosion inhibitor (a), Cobalt hydroxide, cobalt tungstate, sodium tungstate, sodium cobaltate, cobalt phosphate and the like can be mentioned. Among these, cobalt tungstate, cobalt hydroxide, cobalt oxide and cobalt metal are preferable, and cobalt tungstate is particularly preferable.

"Corrosion inhibitor (b)"
The corrosion inhibitor (b) is a reducing agent, and the corrosion of the cemented carbide can be suppressed by reducing the oxidizing agent such as dissolved oxygen in the alkaline liquid chemical solution to prevent the oxidation of the cemented carbide base material.

As a suitable example of a corrosion inhibitor (b), the compound shown by General formula (1) is mentioned, for example, A dihydroxy maleic acid is mentioned as a suitable specific example.
The compound represented by the general formula (1) is considered to reduce the oxidizing agent in the alkaline chemical solution by supplying reducing hydrogen and to suppress the corrosion of the cemented carbide base material.

(Wherein, R ₁ is any of a carboxyl group, an alkyl group having 1 to 6 carbon atoms, an acyl group and an alkoxycarbonyl group, and R ₂ is any of an alkyl group having 1 to 6 carbon atoms, an alkoxy group and a hydroxyl group And R ₁ and R ₂ may form a ring structure, and X ₁ and X ₂ each independently represent a hydrogen atom or an alkali metal.

Further, the compound represented by the R ₁ and R ₂ of the compound represented by the general formula (1) is an example of a case of forming a ring structure formula (2), preferred example of the corrosion inhibitor (b) It is.

(Wherein, R ₃ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, an alkenyl group, an alkynyl group, an acyl group, an alkoxycarbonyl group, n is 0 or 1 and X ₃ and X ₄ are each independently hydrogen Is either an atom or an alkali metal.)

Examples of the compound represented by the general formula (2) include ascorbic acid, sodium ascorbate, erythorbic acid and sodium erythorbate, and it is preferable that the drug solution of the present invention contain at least one of these compounds.

In addition, other preferable examples of the corrosion inhibitor (b) include compounds represented by the general formulas (3-a) and (3-b).

Among the compounds represented by the general formulas (3-a) and (3-b), a compound having at least one set of a hydroxyl group (OH) in an ortho or para positional relationship has a reduction hydrogen after delivery. Is preferable because it forms a six-membered ring of a stable conjugated structure and has a high reducing power.
Examples of the above-mentioned compounds include gallic acid, m-galoyl gallic acid, catechol and hydroquinone, and it is preferable to make the drug solution of the present invention contain at least one of these compounds. Among these, gallic acid is particularly preferred.

In addition, other suitable examples of the corrosion inhibitor (b) include monosaccharides, disaccharides, trisaccharides, tetrasaccharides, oligosaccharides or polysaccharides.
In addition, the saccharides exhibiting reducibility show reducibility by the appearance of an aldehyde group which is a reducible functional group when the cyclic structure is solved to form a chain structure. In addition, some sugars exhibit reducibility by the structural change of the ketone group that appears when the chain structure is obtained, to form an aldehyde group.
Also, due to its structure, disaccharides, trisaccharides, tetrasaccharides, oligosaccharides or polysaccharides that do not have reducibility also exhibit reducibility due to the progress of hydrolysis in the drug solution to produce saccharides having reducibility. . An example of these is sucrose.
Specifically, dihydroxyacetone, erythrulose, erythrose, xylulose, ribose, arabinose, xylose, deoxyribose, psicose, glucose, fructose, sorbose, tagatose, mannose, idose, talose, fucose, rhamnose, maltose, lactose, sucrose, trehalose Tulanose, cellobiose, raffinose, maltotriose, acarbose, stachyose, galactose, ribose, fructooligosaccharide, galactooligosaccharide, mannanoligosaccharide, glycogen, starch, cellulose, dextrin, glucan, levan, inulin, etc. It is preferable to include at least one of these sugars in a drug solution.
Among these, it is preferable that the drug solution of the present invention contains at least one of maltose, lactose, sucrose, glucose and fructose.

Moreover, a phosphorus containing reducing agent or a sulfur containing reducing agent is mentioned as another suitable example of a corrosion inhibitor (b).
The phosphorus-containing reducing agent or the sulfur-containing reducing agent can reduce an oxidizing agent such as dissolved oxygen in the alkaline liquid chemical solution, and can prevent corrosion by preventing the oxidation of the cemented carbide base material. Examples of the phosphorus-containing reducing agent or the sulfur-containing reducing agent include sodium hypophosphite, potassium phosphite, sodium thiosulfate, sodium sulfite and the like. Among these, sodium thiosulfate is preferable.

"Corrosion inhibitor (c)"
The corrosion inhibitor (c) is a type of corrosion inhibitor that binds to a base metal and forms a protective film on the surface to suppress corrosion, and includes an azole compound or a salt thereof, a thiourea compound and an acetylene compound.

An azole compound or a salt thereof, which is an example of a corrosion inhibitor (c), forms a stable film on the surface of a cemented carbide base material by the coordination of the lone electron pair of nitrogen contained in the azole structure to a metal, and oxidation It is considered that the corrosion is suppressed by preventing the intrusion of the agent and the like. Specific examples of the azole compound or a salt thereof include 1H-tetrazole, 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 1-methyl-5-ethyl-tetrazole, 1-methyl-5-mercapto-tetrazole , 5- (2-aminophenyl) -1H-tetrazole, 1-cyclohexyl-5-mercapto-tetrazole, 1-phenyl-5-mercapto-tetrazole, 1-carboxymethyl-5-mercapto-tetrazole and alkali salts thereof Benzotriazole, methylbenzotriazole, dimethylbenzotriazole, hydroxybenzotriazole and the like can be mentioned, among which benzotriazole is preferred.

The thiourea compound which is an example of a corrosion inhibitor (c) is a general term for a compound having a structure represented by the general formula (4) in the molecule, and a polar group containing nitrogen or sulfur constitutes a cemented carbide base material It is believed that it can be chelate-adsorbed to metal elements to prevent the entry of oxidants etc. and to inhibit corrosion. Specific examples of the thiourea compound include thiourea, methylthiourea, dimethylthiourea and ethylenethiourea. Among these, thiourea is preferable.

An acetylene compound, which is an example of a corrosion inhibitor (c), is a generic term for organic compounds containing a C≡C triple bond in the molecule, and provides π electrons of the triple bond to the empty orbital of the base metal element. It is believed that a bond can be formed between the base metal and the base metal, thereby preventing the entry of an oxidant and exhibiting a corrosion suppressing effect. For example, 2-propyn-1-ol, 1-hexyn-3-ol, 3-butyn-1-ol and the like can be mentioned, and 2-propyn-1-ol is preferred.

The addition amount of these corrosion inhibitors is suitably determined in the range which does not impair the effect | action which removes the hard film by the chemical | medical solution of this invention. Further, as described above, the corrosion inhibitor may be used by simultaneously containing a plurality of types in an alkaline chemical solution.
Specifically, the concentration in the alkali chemical solution in the case where only one type of each of the corrosion inhibitors (a), (b) and (c) is added is usually 0. 5 in the case of the corrosion inhibitor (a). It is in the range of 001 to 10 mol / L, preferably 0.01 to 1 mol / L, and in the case of the corrosion inhibitor (b), usually 0.001 to 10 mol / L, preferably 0.01 to 1 mol / L. In the case of the corrosion inhibitor (c), it is usually in the range of 0.001 to 10 mol / L, preferably 0.05 to 2 mol / L.
However, the amount is not limited to this range, and when the amount of the corrosion inhibitor is too large, it may be difficult to remove the hard coating. On the other hand, when the amount is too small, the corrosion inhibiting effect of the carbide base material may be reduced. It is necessary to set the type and concentration of the alkali chemical solution or the processing temperature under optimum conditions in consideration of the removal rate of the hard film and the corrosion inhibition effect of the cemented carbide base material.
As a specific example, a cemented carbide particle is WC, a binder metal is an alloy containing Co as a main component, and a hard film contains at least one compound selected from the group consisting of TiAlN, TiSiN and TiAlCrN. In the case of a layer or multilayer film (thickness: about 1 to 5 μm), tungstic acid as a corrosion inhibitor for a 10 mol / L sodium hydroxide aqueous solution at a temperature of 170 to 220 ° C. When cobalt, cobalt hydroxide and cobalt oxide are used alone, the preferred concentration range is 0.01 to 1 mol / L, and when ascorbic acid, sodium ascorbate, sodium thiosulfate and maltose are used alone, respectively. Concentration range: 0.01 to 1 mol / L, each of benzotriazole and 2-propyn-1-ol alone Suitable concentration ranges of each of the case of use is 0.05 ~ 2mol / L.

In addition, when a plurality of types of these corrosion inhibitors are mixed and used, the preferred concentration range of each corrosion inhibitor tends to decrease as compared with the case where only a single corrosion inhibitor is contained by a synergetic effect. For this reason, it is necessary to set optimum conditions according to the type of caustic agent to be combined.
Preferred concentrations in the case of combination with other corrosion inhibitors are 0.0001 to 0.1 mol / L in the case of corrosion inhibitors (a) and 0.0001 to 0. 0 in the case of corrosion inhibitors (b). 5 mol / L, and in the case of the corrosion inhibitor (c), 0.0005 to 1 mol / L.
As a specific example, a cemented carbide particle is WC, a binder metal is an alloy containing Co as a main component, and a hard film contains at least one compound selected from the group consisting of TiAlN, TiSiN and TiAlCrN. Hydroxide, as a corrosion inhibitor, for a 10 mol / L sodium hydroxide aqueous solution at a temperature of 170 to 220 ° C. when it is composed of a layer or multilayer film (thickness: about 1 to 5 μm) When cobalt and ascorbic acid are mixed and used, the preferred concentration range of each is 0.0001 to 0.1 mol / L of cobalt hydroxide and 0.0001 to 0.5 mol / L of ascorbic acid, each of The preferred concentration range is reduced compared to when used alone.

In addition, the chemical | medical solution of this invention may contain the other addition component in the range which does not impair the objective of this invention other than a corrosion inhibitor. For example, a pH buffer, a stabilizer, a surfactant, a radical scavenger and the like can be added as appropriate.

Next, a preferred embodiment of the present invention will be described. The present invention is not limited to the embodiment described below.

1) Preparation of Alkaline Chemical Solution As described above, alkali hydroxide is suitably used for pH adjustment in the chemical solution of the present invention. The preparation of an aqueous alkali hydroxide solution of a predetermined concentration can be carried out according to the following procedure.
First, a predetermined amount of water is placed in a corrosion resistant container, and a predetermined amount of the selected alkali hydroxide compound is gradually added thereto at room temperature with stirring to dissolve or disperse. In addition, it is preferable to add while cooling, when generation | occurrence | production is accompanied at the time of addition of an alkali hydroxide compound, and a container failure or bumping etc. are considered. Moreover, when adding the above-mentioned corrosion inhibitor to the alkali hydroxide aqueous solution obtained in this way, the quantity which the selected corrosion inhibitor becomes a predetermined concentration is measured, and the measured corrosion inhibitor is the said hydroxylation. The corrosion inhibitor-containing alkali hydroxide aqueous solution may be prepared by gradually adding and dissolving or dispersing it while stirring in an alkaline aqueous solution. The addition of the corrosion inhibitor may be performed simultaneously with or subsequent to the addition of the alkali hydroxide compound.

2) Contact between the cemented carbide and the alkali chemical The contact between the cemented carbide and the alkali chemical may be carried out by immersing the cemented carbide in the alkali chemical, dropping the alkali chemical on the cemented carbide, etc. Usually, it is performed by the method of immersing a superhard material in an alkali chemical | medical solution. Specifically, first, a predetermined amount of an alkali chemical solution capable of completely immersing a cemented carbide material to be removed is placed in a pressure vessel having corrosion resistance to the alkali chemical solution, and then the cemented carbide material is removed at room temperature. Immerse in alkaline chemical solution, close the lid of the pressure container and seal it. At this time, it is preferable to replace the air in the gas phase of the pressure vessel with an inert gas such as nitrogen or argon gas, a reducing gas such as hydrogen sulfide or a vapor generated from an alkaline chemical solution for the purpose of removing the oxidizing gas. .

3) Film removal treatment A pressure-resistant container in which the above-mentioned cemented carbide material is immersed is set in a heating device such as a ventilation oven, an oil bath, or a heater with a steam jacket, and the heating device is heated to a predetermined temperature. Film removal processing is performed by holding for a while. The heating device is not limited to the one described above as long as it can heat at the predetermined temperature of the present invention. The treatment time (immersion time) is appropriately determined in consideration of the film type (constituting element) of the hard film, the film thickness, the treatment temperature, etc., but usually 1 hour to 100 hours (preferably 5 to 72 hours). Time). If the time is too short, film removal may not be sufficient, and film removal is sufficiently performed in 100 hours, so it is often unnecessary to spend more time.

4) Taking out and washing with water After the pressure container set in the heating device is cooled to 60 ° C. or less, the film-removed cemented carbide is taken out from the pressure container, and the cemented carbide is washed with water to obtain an alkaline chemical solution. Remove

5) Drying In order to remove adhering water on the surface of the cemented carbide material from which the alkaline chemical solution has been removed by washing with water, the moisture is removed by drying using a conventional drier to obtain a cemented carbide material from which the hard coating has been removed. The drying and drying conditions are not particularly limited as long as the drying at this time can remove and remove the water.

6) Recoating of Hard Coating The surface of the cemented carbide from which the hard coating has been removed is subjected to ion bombardment cleaning using argon gas to remove impurity layers such as an oxide coating layer formed on the surface. Thereafter, a hard film is formed by a CVD method or a PVD method. In addition, prior to the formation of the hard coating, physical treatment such as solvent washing for removing oil and fat, or blast or polishing for removing the fragile layer generated on the surface of the cemented carbide base material may be performed.
As described above, in the cemented carbide material in which the surface of the cemented carbide base material is coated with the hard coating by the method of the present invention, the hard coating of the defective product at the time of manufacture and the end of life product due to use deterioration is selectively removed It is possible to recycle by coating the hard coating again.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

The reagents, film removing apparatus, and analyzer used are as follows.
"reagent"
-Sodium hydroxide (Wako Pure Chemical Industries, Ltd.)
・ Benzotriazole (Kanto Chemical Co., Ltd.)
-Cobalt tungstate (Mitsuwa Chemical Co., Ltd. product)
-Potassium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.)
・ Ammonia water (made by Takasugi Pharmaceutical Co., Ltd.)
Hydrogen peroxide water (Mitsubishi Gas Chemical Co., Ltd.)
Nitric acid (manufactured by Takasugi Pharmaceutical Co., Ltd.)
2-Propin-1-ol (manufactured by Wako Pure Chemical Industries, Ltd.)
· Gallic acid (Wako Pure Chemical Industries, Ltd.)
· Disodium hydrogen phosphite (manufactured by Wako Pure Chemical Industries, Ltd.)
Sodium thiosulfate (manufactured by Wako Pure Chemical Industries, Ltd.)
・ Maltose (made by Wako Pure Chemical Industries, Ltd.)
Sucrose (manufactured by Wako Pure Chemical Industries, Ltd.)
Glucose (manufactured by Wako Pure Chemical Industries, Ltd.)

"Demembrane processing system"
1) Pressure-resistant container: Specification of Oem Labotech (model: MR98) Maximum operating temperature: 250 ° C, maximum operating pressure: 5MPa
Volume: 98 mL
Material: Outer cylinder SUS316 / inner cylinder PTFE
2) Oven: Specification of FS-620 manufactured by ADVANTEC Internal dimensions: W610 x D 525 x H 500 mm (internal volume: 160 L)
Interior material: SUS304
Operating temperature range: 25 to 250 ° C

"Analysis equipment"
1) -1 Scanning electron microscope (SEM) (manufactured by Nippon Denshi Co., Ltd., model number: JSM5600)
Acceleration voltage: 5kV
Working distance: 10 mm
Spot size: 20
1, 2, 3, 3, 4, 5, 6, 7, 7, 8 and 16 are taken with this camera.
1) -2 Scanning electron microscope (SEM) (manufactured by Nippon Denshi Co., Ltd., model number: JSM 6510)
Acceleration voltage: 5kV
Working distance: 10 mm
Spot size: 20
9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 24, 35, 36. Shot with this unit.
2) Energy dispersive X-ray analyzer (EDX) (EDAX INC., Model number: Genesis XM2)
SEM side condition (manufactured by Nippon Denshi Co., Ltd., model number: JSM 6510)
Acceleration voltage: 20kV
Working distance: 10 mm
Spot size: 50
EDX side condition (at cross section mapping)
Mapping pixel count: 512 × 400
Accumulated number of times: 64 times 3) Hard film adhesion strength measuring device (manufactured by CSM Instruments SA, model number: RVT 9-181)
(Measurement principle)
The film surface is scratched by moving the table at a speed of 10 mm / min while applying a load at a speed of 100 N / min using an indenter with a tip of 120 ° ± 30 ′ tip ± 0.2 R ± 0.02.

"Hard film forming device"
Arc ion plating system (made by Kobe Steel, model number: AIP70TK)
(Coating conditions)
The target with the composition Ti: Al = 50: 50 was used to form a monolayer film without an intermediate layer. During the treatment, the table was rotated and treated under conditions, a work temperature of 420 ° C., and a coating time of 60 minutes.

The tools used in Examples and Comparative Examples are shown in Table 1.

Example 1
In a 100 mL volumetric flask, 40 g of sodium hydroxide was weighed, to which pure water was gradually added and dissolved, and the solution was cooled to room temperature and then adjusted to 100 mL to prepare an alkaline chemical solution.
60 mL of this preparation liquid is charged in the above-mentioned pressure container, and subsequently, a cemented carbide base material comprising an alloy in which the cemented carbide particles are WC and the binder metal is mainly Co (hereinafter referred to as “WC / Co based super An end mill (φ 6 mm, length 50 mm, blade length 20 mm) in which two layers of TiAlN and TiAlCrN are coated on the surface of a hard base material) as a compound constituting a hard film, The pressure container was sealed by immersing in a chemical solution. The film thickness of the hard film is about 4 μm.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 200 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven became 60 ° C or less, the end mill was taken out from the pressure container, sufficiently washed with pure water, and then water was removed by air blow to obtain a film removal treatment end mill . The surface SEM image (1000 times) of the end mill (base material) after processing is shown in FIG. The film removal conditions and the evaluation results are shown in Table 2. In addition, in the surface SEM image of the end mill (base material) after the treatment, there was no noticeable change in appearance with the surface SEM image (not shown) of the end mill (base material) before the treatment.

Example 2
40 g of sodium hydroxide and 1.2 g of benzotriazole were weighed in a 100 mL volumetric flask, pure water was gradually added to this, dissolved, cooled to room temperature, and then made constant to 100 mL to prepare an alkaline chemical solution. 60 mL of this preparation solution is taken while stirring, and charged into the above-mentioned pressure-resistant container, and subsequently a drill (φ 6 mm) in which TiSiN and TiAlCrN are alternately multi-layeredly coated as a hard coating on the surface of WC / Co cemented carbide base material. , 82 mm in length and 42 mm in blade length) were immersed in the above alkaline chemical solution to seal the pressure resistant container. The film thickness of the hard film is about 4 μm.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven became 60 ° C or lower, the drill was taken out from the pressure container, sufficiently washed with pure water, and then water was removed by air blow to obtain a film removal treatment drill . The surface SEM image (1000 times) of the drill (base material) after processing is shown in FIG. The film removal conditions and the evaluation results are shown in Table 2. In addition, in the surface SEM image of the drill (base material) after the treatment, there was no noticeable change in appearance with the surface SEM image (not shown) of the drill (base material) before the treatment.

Example 3
Measure 40 g of sodium hydroxide and 3.4 g of cobalt tungstate in a 100-mL volumetric flask, slowly add pure water to this and dissolve it (cobalt tungstate becomes a slurry because undissolved matter remains), and room temperature After cooling down to a constant volume of 100 mL, an alkaline solution was prepared. 60 mL of this preparation solution is taken and charged in the above-mentioned pressure vessel, and subsequently a drill (φ 6 mm, length) in which TiSiN and TiAlCrN are alternately multi-layered coated as a hard coating on the surface of WC / Co cemented carbide base material The pressure container was sealed by immersing 82 mm, blade length 42 mm) in the alkaline chemical solution. The film thickness of the hard film is about 4 μm.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 200 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven became 60 ° C or lower, the drill was taken out from the pressure container, sufficiently washed with pure water, and then water was removed by air blow to obtain a film removal treatment drill . The surface SEM image (1000 times) of the drill (base material) after processing is shown in FIG. The film removal conditions and the evaluation results are shown in Table 2. In addition, in the surface SEM image of the drill (base material) after the treatment, there was no noticeable change in appearance with the surface SEM image (not shown) of the drill (base material) before the treatment.

Example 4
In a 100-mL volumetric flask, 56 g of potassium hydroxide and 1.2 g of benzotriazole were weighed, and pure water was gradually added thereto, dissolved, cooled to room temperature, and adjusted to 100 mL to prepare an alkaline chemical solution. 60 mL of this preparation solution is taken while stirring, and charged into the above-mentioned pressure-resistant container, and subsequently, a chip (thickness 4.8 mm, side) coated with TiAlN as a hard coating on the surface of WC / Co cemented carbide base material The pressure container was sealed by immersing the 16.5 mm long triangle) in the alkaline chemical solution. The film thickness of the hard film is about 4 μm.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven became 60 ° C or lower, the chip was taken out from the pressure container, sufficiently rinsed with pure water, and then water was removed by air blow to obtain a film-removed chip . The surface SEM image (1000 ×) of the chip after treatment is shown in FIG. The film removal conditions and the evaluation results are shown in Table 2. In the surface SEM image of the processed chip, there was no noticeable change in appearance with the surface SEM image (not shown) of the chip before processing.

Example 5
40 g of sodium hydroxide and 1.2 g of benzotriazole were weighed in a 100 mL volumetric flask, pure water was gradually added to this, dissolved, cooled to room temperature, and then made constant to 100 mL to prepare an alkaline chemical solution. 60 mL of this preparation solution is taken while stirring, and charged into the above-mentioned pressure-resistant container, and subsequently a drill (φ 6 mm) in which TiSiN and TiAlCrN are alternately multi-layeredly coated as a hard coating on the surface of WC / Co cemented carbide base material. , 82 mm in length and 42 mm in blade length) were immersed in the above alkaline chemical solution to seal the pressure resistant container. The film thickness of the hard film is about 4 μm.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 200 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven became 60 ° C or lower, the drill was taken out from the pressure container, sufficiently washed with pure water, and then water was removed by air blow to obtain a film removal treatment drill . The surface SEM image (1000 times) of the drill (base material) after processing is shown in FIG. The film removal conditions and the evaluation results are shown in Table 2. In addition, in the surface SEM image of the drill (base material) after the treatment, there was no noticeable change in appearance with the surface SEM image (not shown) of the drill (base material) before the treatment.

Example 6
In a 100 mL volumetric flask, 40 g of sodium hydroxide was weighed, to which pure water was gradually added and dissolved, and the solution was cooled to room temperature and then adjusted to 100 mL to prepare an alkaline chemical solution. 60 mL of this preparation liquid is charged in the above-mentioned pressure-resistant container, and subsequently, a throwaway tip (12 mm on a side, 3 mm in thickness, a quadrangle of cobalt content 2.5 weight) where the carbide base material is a WC / Co cemented carbide base material. A cemented carbide tool having a hard coating (film thickness 4 μm) mainly composed of TiAlN formed on a surface of the%) using a PVD apparatus was immersed in the alkali chemical solution to seal the pressure resistant container.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after treatment is shown in FIG. 9 and the physical properties of the film-deposition treated throw-away tip are shown in Table 2. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating. After film removal treatment, ion bombard cleaning using argon gas was performed for 75 minutes to clean the surface of the indexable tip. After cleaning, using the target of Ti: Al = 50: 50 and nitrogen as the process gas, the pressure in the chamber is 4 Pa, the work temperature is 420 ° C., the film forming speed is 2 to 4 μm / hr, and the bias voltage is 30 V A hard coating was formed on the surface of the film removal indexable tip under the following conditions. It was 36.0 newtons compared with new article: 60.5 newtons when it compared with the film adhesion strength of the new indexable inserts which did not perform coating processing, and the throwaway tips which formed and reproduced hard coating. The film removal conditions and the film adhesion strength evaluation results are shown in Table 4.

Example 7
Measure 40 g of sodium hydroxide and 3.4 g of cobalt tungstate in a 100-mL volumetric flask, slowly add pure water to this and dissolve it (cobalt tungstate becomes a slurry because undissolved matter remains), and room temperature After cooling down to a constant volume of 100 mL, an alkaline solution was prepared. The same cemented carbide tool as in Example 6 in which 60 mL of this preparation liquid was charged in the above-described pressure resistant container and then a hard coating mainly composed of TiAlN was formed on the throwaway tip was immersed in the alkali chemical solution to Was sealed.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. 10, and the physical properties of the film-deposition treated throw-away tip are shown in Table 3. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating, and it was determined by the SEM-EDX method The surface cobalt concentration was measured and found to be 2.4% by weight. Moreover, the cross-sectional analysis result of the throw away tip after this process is shown in FIG. As a result of cobalt mapping analysis in the surface depth direction by the SEM-EDX method, cobalt desorption was not found. After film removal treatment, ion bombard cleaning using argon gas was performed for 75 minutes to clean the surface of the indexable tip. After cleaning, using the target of Ti: Al = 50: 50 and nitrogen as the process gas in the above-mentioned PVD apparatus, the pressure in the chamber is 4 Pa, the work temperature is 420 ° C., the film forming speed is 2 to 4 μm / hr, and the bias voltage is 30 V A hard coating was formed on the surface of the film removal indexable tip under the conditions. The film adhesion strength between a hard coating formed and regenerated indexable insert and a new indexable insert which has not been subjected to a film removal treatment is as good as 65.1 newton compared to 60.5 new. The The film removal conditions and the film adhesion strength evaluation results are shown in Table 4.

Example 8
40 g of sodium hydroxide and 1.2 g of benzotriazole were weighed in a 100 mL volumetric flask, pure water was gradually added to this, dissolved, cooled to room temperature, and then made constant to 100 mL to prepare an alkaline chemical solution. The same cemented carbide tool as in Example 6 in which 60 mL of this preparation liquid was charged in the above-described pressure resistant container and then a hard coating mainly composed of TiAlN was formed on the throwaway tip was immersed in the alkali chemical solution to Was sealed.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. 11, and the physical properties of the film-deposition treated throw-away tip are shown in Table 2. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating.

Example 9
In a 100 mL volumetric flask, 40 g of sodium hydroxide and 3.5 g of ascorbic acid were weighed, pure water was gradually added to this, dissolved, cooled to room temperature, and then made constant to 100 mL to prepare an alkaline chemical solution. The same cemented carbide tool as in Example 6 in which 60 mL of this preparation liquid was charged in the above-described pressure resistant container and then a hard coating mainly composed of TiAlN was formed on the throwaway tip was immersed in the alkali chemical solution to Was sealed.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 12 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. 12, and the physical properties of the film-deposition treated throw-away tip are shown in Table 3. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating, and it was determined by the SEM-EDX method The surface cobalt concentration was measured and found to be 2.1% by weight. Moreover, the cross-sectional analysis result of the throw away tip after this process is shown in FIG. As a result of cobalt mapping analysis in the surface depth direction by the SEM-EDX method, cobalt desorption was not found. After film removal treatment, ion bombard cleaning using argon gas was performed for 75 minutes to clean the surface of the indexable tip. After cleaning, using the target of Ti: Al = 50: 50 and nitrogen as the process gas, the pressure in the chamber is 4 Pa, the work temperature is 420 ° C., the film forming speed is 2 to 4 μm / hr, and the bias voltage is 30 V A hard coating was formed on the surface of the film removal indexable tip under the following conditions. When compared with the film adhesion strength of a new indexable insert which has a hard coating formed and regenerated and a new indexable insert which has not been subjected to a film removal treatment, it is equal to or higher than 72.5 Newtons compared to new: 60.5 Newtons. The The film removal conditions and the film adhesion strength evaluation results are shown in Table 4.

Example 10
Measure 40 g of sodium hydroxide and 3.5 g of cobalt hydroxide in a 100-mL volumetric flask, slowly add pure water to this and dissolve it (cobalt hydroxide becomes a slurry because undissolved matter remains), and room temperature After cooling down to a constant volume of 100 mL, an alkaline solution was prepared. The same cemented carbide tool as in Example 6 in which 60 mL of this preparation liquid was charged in the above-described pressure resistant container and then a hard coating mainly composed of TiAlN was formed on the throwaway tip was immersed in the alkali chemical solution to Was sealed.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. 13 and the physical properties of the film-deposition treated throw-away tip are shown in Table 3. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating, and it was determined by the SEM-EDX method The surface cobalt concentration was measured and found to be 2.5% by weight. Moreover, the cross-sectional analysis result of the throw away tip after this process is shown in FIG. As a result of cobalt mapping analysis in the surface depth direction by the SEM-EDX method, cobalt desorption was not found.

Example 11
Weigh 40 g of sodium hydroxide and 3.5 g of 2-propyn-1-ol in a 100 mL volumetric flask, slowly add pure water to this, dissolve it, cool to room temperature, and then make up to 100 mL and make an alkaline solution Was prepared. 60 mL of this preparation solution is taken while stirring, and charged into the above-mentioned pressure-resistant container, and subsequently a drill (φ 6 mm) in which TiSiN and TiAlCrN are alternately multi-layeredly coated as a hard coating on the surface of WC / Co cemented carbide base material. (The length 82 mm, blade length 42 mm, cobalt content 6.5 wt%) was immersed in the above alkaline chemical solution to seal the pressure resistant container. The film thickness of the hard film is about 4 μm.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 200 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven became 60 ° C or lower, the drill was taken out from the pressure container, sufficiently washed with pure water, and then water was removed by air blow to obtain a film removal treatment drill . The surface SEM image (1000 times) of the drill (base material) after processing is shown in FIG. The film removal conditions and the evaluation results are shown in Table 3. In addition, in the surface SEM image of the drill (base material) after treatment, there is no noticeable change in appearance with the surface SEM image (not shown) of the drill (base material) before treatment, and the surface cobalt concentration by the SEM-EDX method Was measured to be 6.2% by weight. Moreover, the cross-sectional analysis result of the drill after this process is shown in FIG. As a result of cobalt mapping analysis in the surface depth direction by the SEM-EDX method, cobalt desorption was not found.

Example 12
40 g of sodium hydroxide and 3.5 g of gallic acid were weighed in a 100 mL volumetric flask, pure water was gradually added to this, dissolved, cooled to room temperature, and then made constant to 100 mL to prepare an alkaline chemical solution. The same cemented carbide tool as in Example 6 in which 60 mL of this preparation liquid was charged in the above-described pressure resistant container and then a hard coating mainly composed of TiAlN was formed on the throwaway tip was immersed in the alkali chemical solution to Was sealed.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after treatment is shown in FIG. 17 and the physical properties of the film-deposition treated throw-away tip are shown in Table 2. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating.

Example 13
40 g of sodium hydroxide and 3.5 g of disodium hydrogen phosphite are weighed into a 100 mL volumetric flask, pure water is gradually added to this, dissolved, cooled to room temperature, and made constant to 100 mL to prepare an alkaline chemical solution did. The same cemented carbide tool as in Example 6 in which 60 mL of this preparation liquid was charged in the above-described pressure resistant container and then a hard coating mainly composed of TiAlN was formed on the throwaway tip was immersed in the alkali chemical solution to Was sealed.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. 18 and the physical properties of the film-deposition treated throw-away tip are shown in Table 2. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating.

Example 14
In a 100-mL volumetric flask, 40 g of sodium hydroxide and 3.5 g of sodium thiosulfate were weighed, pure water was gradually added to this, dissolved, cooled to room temperature, and then made constant to 100 mL to prepare an alkaline chemical solution. The same cemented carbide tool as in Example 6 in which 60 mL of this preparation liquid was charged in the above-described pressure resistant container and then a hard coating mainly composed of TiAlN was formed on the throwaway tip was immersed in the alkali chemical solution to Was sealed.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. 19 and the physical properties of the film-deposition treated throw-away tip are shown in Table 2. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating.

Example 15
Weigh 40 g of sodium hydroxide and 3.5 g of cobalt hydroxide in a 100-mL volumetric flask and slowly add pure water to this to dissolve it (cobalt hydroxide becomes a slurry because undissolved matter remains) to room temperature After cooling, the volume was adjusted to 100 mL to prepare an alkaline chemical solution. 60 mL of this preparation liquid was charged in the above-mentioned pressure-resistant container, and then one surface was mirror-polished. A throwaway tip (12 mm on a side, 3 mm in thickness, cobalt) whose cemented carbide substrate is a WC / Co cemented carbide substrate. A cemented carbide tool in which a hard coating (film thickness 4 μm) mainly composed of TiAlN was formed on the surface with a content of 2.5% by weight using a PVD apparatus was immersed in the alkaline chemical solution to seal the pressure resistant container. By mirror-polishing, it can be expected that variations in measured values in the evaluation of film adhesion strength after film removal and recoating described later will be reduced.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the polished surface of the throw away tip after the treatment is shown in FIG. 20, and the physical properties of the film removal treated throw away tip are shown in Table 3. In the surface SEM image of the throwaway tip (base material / polished surface) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 36) of the throwaway tip (base material / polished surface) before hard coating. The surface cobalt concentration was measured by the SEM-EDX method to be 2.2% by weight. Moreover, the cross-sectional analysis result of the throw away tip after this process is shown in FIG. As a result of cobalt mapping analysis in the surface depth direction by the SEM-EDX method, cobalt desorption was not found. After film removal treatment, ion bombard cleaning using argon gas was performed for 75 minutes to clean the surface of the indexable tip. After cleaning, using the target of Ti: Al = 50: 50 and nitrogen as the process gas in the above-mentioned PVD apparatus, the pressure in the chamber is 4 Pa, the work temperature is 420 ° C., the film forming speed is 2 to 4 μm / hr, and the bias voltage is 30 V A hard coating was formed on the surface of the film removal indexable tip under the conditions. The film adhesion strength of a new indexable insert which has a hard coating formed and regenerated and a new indexable insert which has not been subjected to a film removal treatment is compared with that of the coating: Met. In consideration of the fact that the variation in the film adhesion strength measurement value has a range of about ± 15 N from the average value, it can be said that the film adhesion strength of the recycled product is comparable to that of a new product. The film removal conditions and the film adhesion strength evaluation results are shown in Table 5.

Example 16
Measure 40 g of sodium hydroxide, 0.18 g of ascorbic acid and 0.17 g of cobalt tungstate in a 100-mL volumetric flask, slowly add pure water to this and dissolve it (cobalt tungstate remains small as it remains undissolved. The reaction mixture was cooled to room temperature and then adjusted to 100 mL to prepare an alkaline solution. 60 mL of this preparation liquid was charged in the above-mentioned pressure-resistant container, and then one surface was mirror-polished. A throwaway tip (12 mm on a side, 3 mm in thickness, cobalt) whose cemented carbide substrate is a WC / Co cemented carbide substrate. A cemented carbide tool in which a hard coating (film thickness 4 μm) mainly composed of TiAlN was formed on the surface with a content of 2.5% by weight using a PVD apparatus was immersed in the alkaline chemical solution to seal the pressure resistant container. By mirror-polishing, it can be expected that variations in measured values in the evaluation of film adhesion strength after film removal and recoating described later will be reduced.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the polished surface of the throw away tip after the treatment is shown in FIG. 21 and the physical properties of the film removal treated throw away tip are shown in Table 3. In the surface SEM image of the throwaway tip (base material / polished surface) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 36) of the throwaway tip (base material / polished surface) before hard coating. The surface cobalt concentration was measured by the SEM-EDX method to be 2.5% by weight. Moreover, the cross-sectional analysis result of the throw away tip after this process is shown in FIG. As a result of cobalt mapping analysis in the surface depth direction by the SEM-EDX method, cobalt desorption was not found. After film removal treatment, ion bombard cleaning using argon gas was performed for 75 minutes to clean the surface of the indexable tip. After cleaning, using the target of Ti: Al = 50: 50 and nitrogen as the process gas in the above-mentioned PVD apparatus, the pressure in the chamber is 4 Pa, the work temperature is 420 ° C., the film forming speed is 2 to 4 μm / hr, and the bias voltage is 30 V A hard coating was formed on the surface of the film removal indexable tip under the conditions. The film adhesion strength of a new indexable insert which has a hard coating formed and regenerated and a new indexable insert which has not been subjected to a film removal treatment is compared with that of the coating: Met. In consideration of the fact that the variation in the film adhesion strength measurement value has a range of about ± 15 N from the average value, it can be said that the film adhesion strength of the recycled product is comparable to that of a new product. The film removal conditions and the film adhesion strength evaluation results are shown in Table 5.

Example 17
40 g of sodium hydroxide and 7.2 g of maltose were weighed in a 100-mL volumetric flask, pure water was gradually added to this, dissolved, cooled to room temperature, and then made constant to 100 mL to prepare an alkaline chemical solution. The same cemented carbide tool as in Example 6 in which 60 mL of the preparation liquid was charged into the above-mentioned pressure-resistant container in a glove box whose inside was replaced with nitrogen gas, and then a hard coating consisting mainly of TiAlN was formed on the throwaway tip. Was immersed in the alkali chemical solution. Thus, the container was sealed in a form in which the gas phase portion of the pressure container was replaced with nitrogen gas.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating.

Example 18
40 g of sodium hydroxide, 0.34 g of sucrose, and 0.05 g of cobalt hydroxide are weighed into a 100-mL volumetric flask, pure water is gradually added to this, dissolved, cooled to room temperature, and the volume is adjusted to 100 mL and alkali A drug solution was prepared (cobalt hydroxide produces a small amount of precipitate because undissolved matter remains). The same cemented carbide tool as in Example 6 in which 60 mL of the preparation liquid was charged into the above-mentioned pressure-resistant container in a glove box whose inside was replaced with nitrogen gas, and then a hard coating consisting mainly of TiAlN was formed on the throwaway tip. Was immersed in the alkali chemical solution. Thus, the container was sealed in a form in which the gas phase portion of the pressure container was replaced with nitrogen gas.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. 23, and the physical properties of the film-deposition treated throw-away tip are shown in Table 3. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating, and it was determined by the SEM-EDX method The surface cobalt concentration was measured and found to be 2.4% by weight. Moreover, the cross-sectional analysis result of the throw away tip after this process is shown in FIG. As a result of cobalt mapping analysis in the surface depth direction by the SEM-EDX method, cobalt desorption was not found.

Example 19
40 g of sodium hydroxide, 0.18 g of glucose, and 0.05 g of cobalt hydroxide are weighed into a 100-mL volumetric flask, pure water is gradually added to this, dissolved, cooled to room temperature, and the volume is adjusted to 100 mL and alkali A drug solution was prepared (cobalt hydroxide produces a small amount of precipitate because undissolved matter remains). The same cemented carbide tool as in Example 6 in which 60 mL of the preparation liquid was charged into the above-mentioned pressure-resistant container in a glove box whose inside was replaced with nitrogen gas, and then a hard coating consisting mainly of TiAlN was formed on the throwaway tip. Was immersed in the alkali chemical solution. Thus, the container was sealed in a form in which the gas phase portion of the pressure container was replaced with nitrogen gas.
The pressure-resistant container was placed in the above-described heating oven, the temperature was raised to 170 ° C., and film removal treatment was performed at this temperature for 24 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven has dropped to 60 ° C or lower, take out the throwaway tip from the pressure container, wash it thoroughly with pure water, and then remove moisture by air blow to remove film removal treatment. I got a chip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. 24 and the physical properties of the film-deposition treated throw-away tip are shown in Table 3. In the surface SEM image of the throwaway tip (base material) after treatment, there was no noticeable change in appearance with the surface SEM image (FIG. 35) of the throwaway tip (base material) before hard coating, and it was determined by the SEM-EDX method The surface cobalt concentration was measured and found to be 2.5% by weight. Moreover, the cross-sectional analysis result of the throw away tip after this process is shown in FIG. As a result of cobalt mapping analysis in the surface depth direction by the SEM-EDX method, cobalt desorption was not found.

Comparative Example 1
In a 300 mL poly beaker, 106 g of pure water and 86 g of 35% hydrogen peroxide water were weighed and subsequently, 8 g of 25% aqueous ammonia at room temperature was gradually added while stirring to prepare a film removing solution. Then, immerse an end mill (φ 6 mm, length 50 mm, edge length 20 mm) coated with TiAlN and TiAlCrN as a hard coating on the surface of WC / Co cemented carbide base material in this chemical solution, 15 The film was removed at 9 ° C. to 25 ° C. for 9 hours. The film thickness of the hard film is about 4 μm.
After a predetermined time elapsed, the end mill was taken out of the beaker, thoroughly washed with pure water, and then water was removed by air blow to obtain a film removal end mill. The surface SEM image (1000 times) of the end mill (base material) after the treatment is shown in FIG. The film removal conditions and the evaluation results are shown in Table 2. In addition, in the surface SEM image of the end mill (base material) after the treatment, there was no noticeable change in appearance with the surface SEM image (not shown) of the end mill (base material) before the treatment. However, according to visual observation, the metallic gloss of the surface was apparently lost and turned to gray.

Comparative example 2
74 mL of 67.5% nitric acid was placed in a 200 mL glass measuring flask, and the volume was adjusted with pure water to adjust the decoating chemical solution. This solution is charged into a 300 mL glass beaker, and then an end mill (φ 6 mm, length 50 mm, blade) is coated with two layers of TiAlN and TiAlCrN as a hard coating on the surface of WC / Co cemented carbide base material with this chemical solution. The part length was 20 mm, and after raising the temperature to 80 ° C. in a water bath, the film was held for 48 hours for film removal treatment. The film thickness of the hard film is about 4 μm. After a predetermined time elapsed, the end mill was taken out of the beaker, thoroughly washed with pure water, and then water was removed by air blow to obtain a film removal end mill. A surface SEM image (1000 ×) of the end mill after treatment is shown in FIG. The film removal conditions and the evaluation results are shown in Table 2. In addition, the surface SEM image of the end mill (base material) after the treatment had a rough surface (corrosion) compared to the surface SEM image (not shown) of the end mill (base material) before the treatment.

Comparative example 3
40 g of sodium hydroxide and 1.2 g of benzotriazole were weighed in a 100 mL volumetric flask, pure water was gradually added to this, dissolved, cooled to room temperature, and then made constant to 100 mL to prepare an alkaline chemical solution. 60 mL of this preparation solution is taken while stirring, and charged into the above-mentioned pressure-resistant container, and subsequently a drill (φ 6 mm) in which TiSiN and TiAlCrN are alternately multi-layeredly coated as a hard coating on the surface of WC / Co cemented carbide base material. , 82 mm in length and 42 mm in blade length) were immersed in the above alkaline chemical solution to seal the pressure resistant container. The film thickness of the hard film is about 4 μm.
The pressure-resistant container was placed in the above-mentioned heating oven, heated to 95 ° C., and subjected to film removal treatment at this temperature for 48 hours. After a predetermined time elapsed, the oven temperature was set to 20 ° C. for cooling. After confirming that the pressure container temperature in the oven became 60 ° C or lower, the drill was taken out from the pressure container, sufficiently washed with pure water, and then water was removed by air blow to obtain a film removal treatment drill . The surface SEM image (1000 times) of the drill (base material) after the treatment is shown in FIG. The film removal conditions and the evaluation results are shown in Table 2. In addition, the surface SEM image of the drill (base material) after the treatment had a rough surface (corrosion) compared to the surface SEM image (not shown) of the drill (base material) before the treatment.

Comparative example 4
In a 300 mL poly beaker, 106 g of pure water and 86 g of 35% hydrogen peroxide water were weighed and subsequently, 8 g of 25% aqueous ammonia at room temperature was gradually added while stirring to prepare a film removing solution. Subsequently, the same cemented carbide tool as in Example 6 in which a hard coating mainly composed of TiAlN was formed on the indexable tip was immersed in the film removing chemical solution to seal the pressure resistant container, and 39 at 15 ° C to 25 ° C. The film was removed for a while.
After the lapse of a predetermined time, the throwaway tip was taken out of the beaker, sufficiently washed with pure water, and then water was removed by air blow to obtain a film-deposition treated throwaway tip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. 14 and the physical properties of the film-deposition treated throw-away tip are shown in Table 3. The surface SEM image of the indexable tip (base material) after the treatment had a rough surface (corrosion) compared to the surface SEM image of the indexable tip (base material) before hard coating. When the surface cobalt concentration was measured by the SEM-EDX method, it was thought that tungsten carbide of the cemented carbide was detached by the film removing operation because it was higher than the base material before film removal, which is 3.2% by weight. Moreover, the cross-sectional analysis result of the throw away tip after this process is shown in FIG. As a result of cobalt mapping analysis in the surface depth direction by the SEM-EDX method, cobalt desorption was not found. After film removal treatment, ion bombard cleaning using argon gas was performed for 75 minutes to clean the surface of the indexable tip. After cleaning, using the target of Ti: Al = 50: 50 and nitrogen as the process gas in the above-mentioned PVD apparatus, the pressure in the chamber is 4 Pa, the work temperature is 420 ° C., the film forming speed is 2 to 4 μm / hr, and the bias voltage is 30 V A hard coating was formed on the surface of the film removal indexable tip under the conditions. The film adhesion strength of the throwaway chip that has been hard-filmed and regenerated is compared with the film adhesion strength of the new throwaway chip that has not been subjected to film removal treatment. The result was significantly inferior. The film removal conditions and the film adhesion strength evaluation results are shown in Table 4.

Comparative example 5
74 mL of 67.5% nitric acid was added to a 200 mL glass measuring flask, and the volume was adjusted with pure water to prepare a demembraned chemical solution. The entire volume of this solution was charged in a 300 mL glass beaker, and then a cemented carbide tool similar to that of Example 6 in which a hard coating consisting mainly of TiAlN was formed on the throwaway tip was immersed in the decoating solution to make a pressure resistant container. The film was sealed, heated to 80 ° C. in a water bath, and then held for 30 hours for film removal treatment.
After the lapse of a predetermined time, the throwaway tip was taken out of the beaker, sufficiently washed with pure water, and then water was removed by air blow to obtain a film-deposition treated throwaway tip. The surface SEM image (1000 times) of the throw-away tip after the treatment is shown in FIG. 15, and the physical properties of the film-deposition treated throw-away tip are shown in Table 3. The surface SEM image of the indexable tip (base material) after the treatment had a rough surface (corrosion) compared to the surface SEM image of the indexable tip (base material) before hard coating. When the surface cobalt concentration was measured by the SEM-EDX method, most of it was desorbed by the film removal operation with zero weight%. Moreover, the cross-sectional analysis result of the throw away tip after this process is shown in FIG. As a result of cobalt mapping analysis in the surface depth direction by the SEM-EDX method, the cobalt desorption depth was desorbed to a depth of about 12.5 μm from the surface. After film removal treatment, ion bombard cleaning using argon gas was performed for 75 minutes to clean the surface of the indexable tip. After cleaning, using the target of Ti: Al = 50: 50 and nitrogen as the process gas in the above-mentioned PVD apparatus, the pressure in the chamber is 4 Pa, the work temperature is 420 ° C., the film forming speed is 2 to 4 μm / hr, and the bias voltage is 30 V A hard coating was formed on the surface of the film removal indexable tip under the conditions. The film adhesion strength of the throwaway chip with hard coating formed and that of the new throwaway chip not subjected to film removal treatment was compared. The film adhesion strength of the regenerated throwaway chip was 2.0 Newtons compared to that of the new product. The result was significantly inferior. The film removal conditions and the film adhesion strength evaluation results are shown in Table 4.

Table 2 shows the list of removal results of hard coatings in Examples 1 to 5 and Comparative Examples 1 to 3 above, and Table 3 shows the list of removal results of hard coatings on Examples 6 to 10 and Comparative Examples 4 and 5 in Examples. After removing the hard film in 6, 7 and 9 and Comparative Examples 4 and 5, the film was formed with a PVD apparatus, and the result of the film adhesion strength measurement of the reproduced throw-away tip is shown in Table 4. In addition, description of the symbol in Table 2 and Table 3 is shown below.
<Description of symbols in table>
"Delayering possible"
○: Complete film removal, △: Partial film residue, ×: Large film residue “visual appearance”
○: same as base material before treatment (no discoloration), Δ: partial discoloration / surface roughness, ×: overall discoloration / rough “SEM appearance”
○: same as base material before treatment, :: same as base material before treatment, ×: rough all over, "general evaluation"
:: good (pre-treatment base material grade), :: almost good, x: overall corrosion not possible

According to the present invention, it is possible to selectively remove the hard coating on the surface of the cemented carbide base material while minimizing the surface deterioration of the cemented carbide base material in the cemented carbide material. Very useful.

Claims

Cemented carbide particles containing carbides of at least one element selected from the group consisting of Group 4 elements, Group 5 elements and Group 6 elements are selected from the group consisting of Fe, Co, Cu and Ni The surface of a cemented carbide base material sintered with a binder metal consisting of at least one element or an alloy containing these elements is a group 4 element, a group 5 element, a group 6 element, a group 13 element And a hard film containing a nitride, carbide, carbonitride, oxide or boride of at least one element selected from the group consisting of Group 14 elements (with the exception of carbon). A method of removing a hard coating on a cemented carbide material, comprising:
A method of removing a hard film on a cemented carbide, comprising bringing the cemented carbide into contact with an alkaline chemical solution at a temperature of 100 ° C. or more and 250 ° C. or less.
The method for removing a hard film according to claim 1, wherein the alkaline chemical solution contains a corrosion inhibitor of a cemented carbide base material.
The corrosion inhibitor is composed of at least one element selected from the group consisting of a group 4 element, a group 5 element, a group 6 element, Fe, Co, Cu and Ni constituting the cemented carbide base material. The method for removing a hard film according to claim 2, which is a simple substance consisting of at least one element selected from the group or a compound containing said element.
The method for removing a hard film according to claim 3, wherein the corrosion inhibitor is a cobalt compound.
The method for removing a hard film according to claim 4, wherein the corrosion inhibitor is cobalt tungstate, cobalt hydroxide, cobalt oxide or cobalt metal.
The method for removing a hard film according to claim 2, wherein the corrosion inhibitor is a reducing agent.
The method for removing a hard film according to claim 6, wherein the reducing agent is a compound represented by the following general formula (1).

(Wherein, R 1 is any of a carboxyl group, an alkyl group having 1 to 6 carbon atoms, an acyl group and an alkoxycarbonyl group, and R 2 is any of an alkyl group having 1 to 6 carbon atoms, an alkoxy group and a hydroxyl group And R 1 and R 2 may form a ring structure, and X 1 and X 2 each independently represent a hydrogen atom or an alkali metal.
The method for removing a hard film according to claim 7, wherein the reducing agent is dihydroxymaleic acid.
The method for removing a hard film according to claim 7, wherein the reducing agent is a compound represented by the following general formula (2).

(Wherein, R 3 is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, an alkenyl group, an alkynyl group, an acyl group, an alkoxycarbonyl group, n is 0 or 1 and X 3 and X 4 are each independently hydrogen Is either an atom or an alkali metal.)
The method for removing a hard film according to claim 9, wherein the reducing agent is at least one selected from ascorbic acid, sodium ascorbate, erythorbic acid and sodium erythorbate.
The method for removing a hard film according to claim 6, wherein the reducing agent is a compound represented by the following general formula (3-a) or (3-b) and / or a salt thereof.

(In the formulas (3-a) and (3-b), R 4 is a carboxyl group, an aldehyde group, an alkoxy group, an alkoxycarbonyl group, or an acyl group, and R 5 is a hydrogen atom or a hydroxyl group.)
The method for removing a hard film according to claim 11, wherein the reducing agent is at least one selected from gallic acid, m-galoyl gallic acid, catechol and hydroquinone.
The method for removing a hard film according to claim 6, wherein the reducing agent is a monosaccharide, disaccharide, trisaccharide, tetrasaccharide, oligosaccharide or polysaccharide.
The reducing agent is dihydroxyacetone, erythrulose, erythrose, xylulose, ribose, arabinose, xylose, deoxyribose, psicose, glucose, fructose, sorbose, tagatose, mannose, idose, talose, fucose, rhamnose, maltose, lactose, sucrose, trehalose , Tulanose, cellobiose, raffinose, maltotriose, acarbose, stachyose, galactose, ribose, fructooligosaccharide, galactooligosaccharide, mannanoligosaccharide, glycogen, starch, cellulose, dextrin, glucan, levan and inulin The method for removing a hard film according to claim 13.
The method for removing a hard film according to claim 6, wherein the reducing agent is a phosphorus-containing reducing agent or a sulfur-containing reducing agent.
The method for removing a hard film according to claim 15, wherein the reducing agent is disodium hydrogen phosphite or sodium thiosulfate.
The method for removing a hard film according to claim 2, wherein the corrosion inhibitor is at least one compound selected from the group consisting of an azole compound or a salt thereof, a thiourea compound and an acetylene compound.
The method for removing a hard film according to claim 17, wherein the azole compound is benzotriazole.
The method for removing a hard film according to claim 17, wherein the thiourea compound is thiourea.
The method for removing a hard film according to claim 17, wherein the acetylene-based compound is at least one selected from 2-propyn-1-ol, 1-hexyn-3-ol, and 3-butyn-1-ol.
21. The hard film according to any one of claims 1 to 20, wherein the cemented carbide particles contain a carbide of at least one element selected from the group consisting of W, Ti, Nb, Ta, V and Cr. How to remove
The method for removing a hard film according to any one of claims 1 to 21, wherein the binder metal contains Co.
The hard film according to any one of claims 1 to 22, wherein the hard film contains a nitride, carbide or carbonitride of at least one element selected from the group consisting of Ti, V, Cr, Si and Al. Hard coating removal method.
The hard film according to any one of claims 1 to 23, wherein the hard film contains at least one compound selected from the group consisting of TiN, TiAlN, TiSiN, TiAlCrN, CrN, TiCrN, VN, TiC and TiCN. How to remove the film.
The method for removing a hard film according to any one of claims 1 to 24, wherein the hard film is composed of a single layer or a multilayer film.
Alkaline chemical is, 1 ~ 20 mol / L - removal of any one of claims 1 to 25 containing an alkali metal hydroxide and / or alkaline earth metal hydroxide (OH equivalent) hard coating Method.
The method for removing a hard film according to claim 26, wherein the alkaline chemical solution contains 1 to 20 mol / L (OH - equivalent) of sodium hydroxide and / or potassium hydroxide.
28. The method according to any one of claims 1 to 27, wherein the hard coating is removed from the cemented carbide in an airtight processing vessel in which the gas phase part is replaced with an inert gas and / or a reducing gas and / or a vapor generated from an alkaline chemical solution. The method for removing a hard film according to any one of the preceding claims
A method for producing a superhard material coated with a hard coating, comprising removing the hard coating by the method of removing a hard coating according to any one of claims 1 to 28, and forming a hard coating again.