JP2000212743A - Surface coated sintered alloy excellent in peeling resistance and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a surface coated sintered alloy in which the peeling resistance of a hard film is improved to improve the life of a tool by removing a work deteriorated layer, particularly cracks as the work deteriorated layer caused by machining remaining on the surface of the base material of a sintered alloy of cement carbide or cermet and coating the base metal surface freed from the work deteriorated layer with a hard film and the process for producing the same. SOLUTION: This is a surface coated sintered alloy in which, in the base metal of a sintered alloy of cemented carbide or cermet contg. a hard phase and a bonding phase, at least a part of the surface of the base metal is machined, and the surface of the base metal is coated with a hard film having hardness higher than that of the base metal by one or >= two layers of lamination, and, into the particles of the hard phase on the surface side of the base metal coated with the hard film, cracks caused by the machining are put out of existence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated sintered alloy used for cutting tools such as throw-away tips, drills and end mills and various wear-resistant tools and parts, and a method for producing the same. , To remove the cracks as the work-affected layer due to machining remaining on the base material surface of the cemented carbide or sintered alloy made of cermet, especially cracks as the work-affected layer, BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated sintered alloy in which the hard film is improved in peeling resistance by coating to improve tool life and a method for producing the same.

[0002]

2. Description of the Related Art Among sintered alloys, a hard film such as TiC, TiCN, TiN, or Al ₂ O _{3 is formed on a} base material of a cemented carbide by a chemical vapor deposition method (hereinafter referred to as a “CVD method”) or a physical vapor deposition method. Surface-coated sintered alloys (hereinafter referred to as “PVD method”) are often used as cutting tools, wear-resistant tools and parts because they have both the strength and toughness of the base material and the wear resistance of the hard film. ing. However, if the adhesiveness between the base material and the hard film is poor, the hard film is peeled off during use, so that it is rapidly worn and its life is shortened. Therefore, in order to ensure adhesion, various methods such as adjusting the surface of the base material, interposing an underlayer between the base material and the hard film, selecting the film quality of the underlayer, and optimizing the coating conditions of the underlayer. Have been tried. Generally, since the base material of the surface-coated sintered alloy is formed according to the intended use by grinding or the like, grinding dust is attached to the base material at a depth of 1 to 5 μm from the base material surface, and hard phase particles are formed. Cracks in the inside, interface defects between the hard phase particles or between the hard phase particles and the binder phase, and a work-affected layer typified by transformation of the binder phase remains.

The deteriorated layer tends to lower the adhesion strength between the base material and the hard film. For this purpose, it is important to take measures against the work-affected layer, specifically, treatments such as adjusting the roughness of the base material surface, adjusting the alloy composition, and modifying the work-affected layer. As one type of this treatment method, washing with an acid or alkali is performed in the step before coating the hard film, but the deteriorated layer can hardly be removed. On the other hand, in the process of coating a hard film by the CVD method, due to chemical reactions and diffusion phenomena due to the temperature rising atmosphere during the coating process, the temperature at the time of coating the underlayer, gas conditions, film types, etc. Although it is possible to remove grinding debris, it is not possible to remove cracks in hard phase particles existing near the base material surface. Further, in the hard film coating step by the PVD method, the bombardment treatment before the coating step can remove the work-affected layer from the surface of the base material to within several μm, but the work-affected layer is uniformly formed over the entire surface of the base material. There is a problem that it is difficult to remove, or it is difficult to remove a work-affected layer on a target surface portion.

Hitherto, as a means of reducing or removing a work-affected layer and improving the peel strength of a surface-coated cemented carbide, a method of controlling the grinding condition and adjusting the surface roughness of the base material and a method of re-working the base material have been proposed. A method of sintering has been proposed. As a method of adjusting the base material surface roughness, a typical method is disclosed in
-108253, and as a resintering method,
Representative examples are JP-A-5-123903 and JP-A-7-97603. On the other hand, representative examples of applying electropolishing as a pre-coating treatment for a surface-coated sintered alloy before coating are disclosed in JP-A-63-134660, JP-A-8-92741, and JP-A-10-130092.
And Japanese Patent Publication No. 10-510877.

[0005]

The prior art, Japanese Patent Application Laid-Open No. Hei 6-108253, discloses that the base material surface of a cemented carbide is
For example, the average surface roughness Ra is 0.15 by brush polishing.
A coated cemented carbide is disclosed in which a hard film is coated on a surface having a polishing scratch formed in a random direction in a thickness of about 0.4 μm. Although the coated cemented carbide disclosed in the publication increases the adhesive strength between the hard film and the base material, the removal of the work-affected layer is insufficient, so that the base material at the interface between the hard film and the base material is insufficient. There is a problem that cracks remain in the hard phase particles in the material and abnormal damage due to film peeling easily occurs.

[0006] Japanese Patent Application Laid-Open No. 5-123903 discloses that the surface of a base material of a cemented carbide is ground, then re-sintered in a high-pressure inert gas atmosphere at a temperature not lower than a liquid phase appearance temperature. A method of manufacturing a surface-coated cemented carbide cutting tool member in which a hard film is formed by a CVD method is disclosed in Japanese Patent Application Laid-Open No. 7-97603. Disclosed is a diamond coating base material in which a 0.03 mm arc honing process is performed and then resintering in an atmosphere of 1% N ₂ -Ar to form a nitrogen-containing uneven layer on the base material surface and a method for producing the same. ing. In the base material heated surface by re-sintering disclosed in both of these publications, since the work-affected layer is removed and an irregular surface is formed by the grain growth of tungsten carbide or a cubic structure compound, the peel strength is improved. However, since the surface of the film after the coating of the hard film also has irregularities on the surface, the material to be processed is liable to adhere during use, conversely, film peeling increases, and the finished surface accuracy of the material to be processed also decreases. There's a problem. Furthermore, since the resintering causes a change in the component composition of the base material, it becomes difficult to control the composition of the base material heating surface, particularly the amount of the binder phase and the amount of the cubic structure compound, and the base material and the hard film are hardly controlled. There is also a problem that the adhesion strength is not stable.

On the other hand, JP-A-63-134660, which is a prior art relating to an electrolytic solution, discloses that a base material surface of a titanium carbonitride-based cermet is preliminarily treated with an alkali (including an electrolytic treatment) and then subjected to a CVD method. A method for producing a surface-coated titanium carbonitride-based cermet coated with a hard film is disclosed. The electrolysis treatment using an alkaline solution of NaOH and KOH disclosed in the above publication improves the adhesion strength to the hard film by activating the surface of the base material. Since titanium carbonitride is the main component, electrolytic products such as titanium hydroxide are likely to remain and uniform electrolytic polishing is difficult. Also, depending on the electropolishing conditions, cracks (grooves due to electrolytic corrosion) are likely to be generated in the hard phase particles on the surface of the base material, and a porous layer is formed on the surface of the base material because almost no bonding phase is electrolyzed. There is a problem that burrows are easily generated at the interface after coating.

[0008] Japanese Patent Application Laid-Open No. 8-92741 discloses that
After embedding ceramic particles in the surface of the cemented carbide base material, the surface treatment of diamond deposited cemented carbide with irregularities consisting of triangular pyramid-shaped projections is performed by electrolytic etching using mineral acid as an electrolyte. A method is disclosed,
Japanese Patent Application Laid-Open No. Hei 10-130992 discloses that after forming a large uneven surface on the surface of a base material of a sintered alloy by subjecting the surface of the base material of the sintered alloy to strong electrolytic treatment with a strong alkaline solution and then removing the binding phase by acid treatment. Surface treatment method for a coated sintered alloy coated with a hard film of diamond, diamond and / or diamond-like carbon. The electrolytic treatment disclosed in both these publications, in order to improve the adhesion between the diamond hard film and the base material by wedge-shaped mechanical holding force,
This method forms a large uneven surface on the base material surface by electrolytic polishing, and is an effective method for a diamond film that is difficult to adhere due to diffusion between the base material and the hard film, but the hard film surface after coating is also extremely rough. There's a problem.

These conventional electropolishing techniques rapidly dissolve and remove the edge of a cemented carbide tool by corrosion and electrochemical reaction caused by an oxidizing strong acid. It is excellent in terms of mass productivity and cost. However, because the surface of the treated surface is severe and the binder phase near the surface is removed preferentially, a large number of pits are generated immediately below the film when the hard film is coated, and the film peels off. There is a problem that it becomes easier.

[00010]

SUMMARY OF THE INVENTION The present inventors have been studying a method for greatly improving the peel strength of a film on a surface-coated sintered alloy for many years. The surface of the base material of the sintered alloy processed in step 2 shows that the surface of the base material has not been subjected to grinding, and that the surface of the base material has not been ground. In addition, there are surface layers with excessively large or small number of coarse hard particles and binder phase, and when the hard film is coated on the surface of the base material, the peel strength of the hard film is reduced. In particular, the removal of fine hard phase particles and cracks in the hard phase particles remaining at the interface between the cemented carbide base material and the hard film significantly improves the peeling strength and dramatically improves practical performance. And smoothing of the surface and adjustment of the surface composition. The complete removal of Luo defect, a mixture of a hydroxide and ferricyanide salts of Group 1a elements of the periodic table, nitrites, sulfites Group 1a elements of the periodic table, phosphites,
It is most preferable to perform electropolishing in a solution containing at least one selected from carbonates as an essential component, and a coated cemented carbide in which a hard film is coated on the surface of an electrolytically treated base material,
The inventors have found that the present invention has excellent peel strength, and have completed the present invention.

The surface-coated sintered alloy excellent in peeling resistance according to the present invention comprises at least a part of a base metal of a cemented carbide or a cermet-based sintered alloy containing a hard phase and a binder phase. Is machined, and the surface of the base material is
A surface-coated sintered alloy in which a hard film having a hardness higher than that of the base material is coated in one or two or more layers, and in the hard phase particles on the surface of the base material covered with the hard film. Wherein no cracks due to the machining are present.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The base material of the surface-coated sintered alloy of the present invention specifically includes a hard phase composed of only tungsten carbide and a binder phase containing Co and / or Ni as a main component. For example, WC-Co alloy, WC-Ni alloy, WC- (Co, Ni) alloy, WC- (Ni-C
r) -based alloy, WC- (Co, Cr) -based alloy, WC- (C
(o, Cr, V) based alloy, or a hard phase composed of tungsten carbide and a cubic structure compound, and a binder phase mainly composed of Co, for example, WC-TaC-
Co-based alloy, WC- (W, Ti, Ta) C-Co-based alloy, WC- (W, Ti, Ta, Nb) (C, N) -Co
Based alloys, Ti (C, N), Ti
A hard phase mainly composed of N and TiC, and a binder phase mainly composed of Co and / or Ni.
(C, N)-(Ti, W) C- (Co, Ni) -based alloy,
Ti (C, N)-(Ti, W) (C, N)-(Co, N
i) alloy, Ti (C, N)-(Ti, W, Ta) C- (Co, Ni) alloy, Ti (C, N)-(Ti, W,
Ta) A cermet made of a (C, N)-(Co, Ni) alloy can be used.

Among them, a hard phase composed of tungsten carbide and a cubic structure compound, Co and / or N
In the case of a cemented carbide composed of a binder phase containing i as a main component,
Excellent properties such as strength, toughness and hardness of the base material, adhesion between the base material and the hard film, and excellent balance between both,
This is preferable because abrupt damage to the base material after the hard film is worn is small. Also, the amount of the binder phase contained in these alloys depends on the properties of the alloy and the ease of manufacturing the alloy, and so on.
What consists of 3-30 volume% is preferable.

The hard film to be coated on these base materials is a film of diamond, diamond-like carbon, hard boron nitride, cubic boron nitride, or 4a, 5a of the periodic table.
Examples thereof include a single layer or a laminate of two or more elements selected from the group consisting of elements a and 6a, carbides, nitrides, oxides of Al and Si, and mutual solid solutions thereof. Among these hard films, single-layer films include, for example, TiC, TiCN, TiN, (Ti, Zr) N, (T
i, Al) N and CrN are preferable because they are excellent in abrasion resistance and welding resistance.
Film coated in the order of N / TiCN / TiN, TiN / T
a film coated in the order of iC / Al ₂ O ₃ , TiN / TiCN
/ TiC / Al ₂ O ₃ / TiN coated film in this order, Ti
There may be mentioned a combination represented by a film coated in the order of N / (Ti, Al) N / TiN, TiN / Si ₃ N ₄ and a film coated in the order of CrN / VN.

The configuration of the positional relationship between the base material and the hard film is as follows.
When the hard film is coated directly adjacent to the base material, a softer material, such as Ti, than the base material, is provided between the base material and the hard film.
A typical example is a case where an underlayer made of one or more metals or alloys of Zr, W, and Mo is interposed. The thickness of these hard films depends on the presence or absence of an underlayer,
It is necessary to adjust according to the film configuration, application, shape, etc. of all film types and their combinations. In particular, when the film is manufactured by the CVD method or the PVD method, when the thickness is 1 to 20 μm, the abrasion resistance and the peeling resistance are reduced. This is preferable because it is excellent. These hard films may be of stoichiometric or non-stoichiometric composition, and in particular, the T
In the case of a single layer or a lamination of the i-containing compound, it is highly possible that the compound has a non-stoichiometric composition.

The cracks in the hard phase particles on the surface of the base material coated with the hard film are specifically observed by scanning electron microscope observation of the cross-sectional structure of the surface-coated sintered alloy. Is determined by confirming the presence or absence of fine cracks that propagate or penetrate from the surface to the inside of the hard phase particles of the WC hard phase particles and the cubic structure compound such as (W, Ti, Ta) C. it can. The cracks in the hard phase particles are generated immediately below the base material surface by mechanical processing such as grinding with a diamond grindstone.

When the hard film is coated directly adjacent to the base material, the hard phase particles on the surface of the coated base material have a size exceeding 0.2 μm. In this case, it is preferable because the resistance to peeling tends to be excellent. In particular, it is preferable to form hard phase particles exceeding 0.2 μm over the entire surface including the surface of the unprocessed base material. Specifically, the work-affected layer is removed on one or the entire surface of the surface of the base material of the sintered alloy to be present as coarse hard phase particles.

Further, the hard film is made of 4a, 5a, 6 in the periodic table.
group a element, aluminum, silicon carbide, nitride,
When the hard film is composed of one single layer or a laminate of two or more types selected from oxides and their mutual solid solutions, and the hard film is coated directly adjacent to the base material, the hard film is bonded. It is preferable to locally form irregularities of less than 2.0 μm on the surface of the base material to be formed, particularly on all interfaces including the surface of the base material that is not machined, because the peeling resistance is further excellent. Specifically, it means that unevenness of the sintered skin surface of the base material surface of the sintered alloy or unevenness due to grinding scratches is smoothed.
2.0 relative to the average level of any interface in the range of 0 μm
It has irregularities of less than μm.

Further, the hard film is made of any one of 4a, 5a,
A hard film directly adjacent to the base material, which is composed of one single layer or a laminate of two or more selected from the group 6a elements, aluminum, silicon carbides, nitrides, oxides and mutual solid solutions thereof; In the case where the hard film is coated with the hard film, the bonding interface between the hard film and the hard phase particles on the surface of the base material, particularly at the entire interface including the hard film and the non-machined base material surface. When the area ratio of the adhesive interface between the hard film and the binder phase on the base material surface is 0.4 to 0.8,
It is preferable because practical peel resistance is further excellent. Specifically, this area ratio means that the amount of the bonding phase at the interface is slightly larger than the inside of the alloy, and is effective in preventing peeling from immediately below the interface. When the area ratio is less than 0.4, the effect of improving the peeling resistance tends to be weak, and when the area ratio is larger than 0.8, burrows are generated, and the peeling resistance tends to decrease.

In addition, a hard phase whose base material is tungsten carbide and a cubic structure compound composed of carbides, nitrides, carbonitrides of metals belonging to groups 4a, 5a and 6a of the periodic table, and a mutual solid solution thereof; And / or a cemented carbide composed of a binder phase containing Ni as a main component, the surface of the base material directly bonded to the hard film, particularly on the entire surface including the unmachined base material surface It is preferable that the amount of the cubic structure compound on the surface of the base material is reduced or no longer contained in the surface of the base material relative to the amount of the cubic structure compound contained in the base material, because practical peel resistance is further excellent. Specifically, the (W, Ti, Ta) C present on the sintered surface or ground surface of the WC- (W, Ti, Ta) C-Co-based cemented carbide base material
Particles are removed preferentially, and a hard film is coated after forming a surface consisting only of WC and Co.

The surface-coated sintered alloy of the present invention can be produced by making use of the conventional powder metallurgy technology and surface treatment technology. However, the following production method is simple and preferable in the production process. Is the way. That is, the method for producing a surface-coated sintered alloy of the present invention includes a first step of machining at least a part of the surface of a cemented carbide or a cermet sintered alloy base material containing a hard phase and a binder phase; After machining, the base material surface is electropolished in an alkaline electrolyte to remove a machining-damaged layer remaining on the base material surface due to the machining, and a second step of removing the processing-damaged layer. Covering the surface of the base material with a hard film having a higher hardness than the base material in one or two or more layers.

The method of machining the surface of the base material in the first step of the manufacturing method of the present invention is, for example, a grinding stone, a brush, a lap, a blast, a barrel, a grinding, or the like which has been conventionally performed. Grinding and / or lapping the base material surface by a method represented by ultrasonic processing in a liquid containing grains. Of these, the other method except for the barrel processing is preferable because the surface of the base material after the manufacturing method of the present invention is flat and electrolytically wrapped.

The electrolytic solution used in the second step of the production method of the present invention is, for example, NaOH, KOH, LiOH, NaNO ₂ , KNO ₂ , N
_{a 2 S0 3, Na 2 HPO} 3 1a group metal hydroxides of the Periodic Table such as nitrites, sulfites, phosphites, and at least one of the essential components selected from among carbonates, sodium tartrate , Potassium nitrate, sodium phosphate, sodium sulfate, borax, Rochelle salt, sodium tungstate,
Examples thereof include one type of solution selected from aqueous solutions of salts such as potassium ferricyanide and organic solvents such as amines and alcohols.

When these electrolytic solutions are composed of an aqueous solution containing sodium and / or potassium nitrite as a main component, the surface of the base material becomes an electropolished surface having a smooth and slightly enriched binder phase. preferable. When the electrolytic solution is composed of an aqueous solution containing sodium and / or potassium carbonate and ferricyanate as main components, the cubic structure compound is preferentially removed from the surface of the base material, and the bonding phase is reduced. This is preferred because an enriched surface is obtained. In addition, the electrolyte is sodium and / or potassium nitrite,
It is preferable to use an aqueous solution containing a carbonate and a chloride as main components, since the amount of the binder phase on the surface of the base material can be controlled by the component ratio.

As conditions for performing electropolishing using these electrolytic solutions, first, the apparatus can be used in almost the same state as the apparatus used for electropolishing of metal. For example, the solution concentration: 50 to 3
00 g / l, voltage: 1 to 5 V, current value: 0.02 to 0.
5 A / cm ² , electrolysis time: 0.2 to 5 min.

A method for coating the surface of the base material thus manufactured with a hard film is a conventional method of CVD.
It can be produced by a method, a plasma CVD method, or a method combining one or two or more of PVD methods represented by an ion plating method and a sputtering method.
In addition to this hard film, when an underlayer is interposed between the base material and the hard film, the underlayer can be formed by the above-described CVD method, plasma CVD method, or PVD method. In addition, it can also be produced by a dry treatment method such as carburizing treatment or nitriding treatment by gas treatment or a wet treatment method such as electrolytic plating, electroless plating, carburizing treatment by immersion heating in a solution, or nitriding treatment. .

[0027]

The surface-coated sintered alloy of the present invention is characterized in that no cracks are present in the hard phase particles in the base material on the surface of the base material coated with the hard film, preferably on the entire surface of the base material. Acts to improve the properties and suppress the growth of cracks generated by external impact, in some cases, the absence of fine hard phase particles on the surface of the base material at all interfaces between the base material and the hard film, That the interface is smooth, that the bonding area ratio between the hard film and the bonding phase of the base material on the surface of the base material in the interface is larger than the bonding area ratio between the hard film and the hard phase particles of the base material, The absence of cubic structure compound particles on the surface of the base material further enhances the peeling resistance of the film, absorbs external shocks, suppresses the occurrence of cracks, and cracks generated by external shocks Restrain progress It is one that has the effect.

The method for producing a surface-coated sintered alloy according to the present invention is characterized in that at least one surface of the base material surface is subjected to electrolytic polishing and / or electrolytic lapping with an alkaline electrolytic solution on an affected layer formed by mechanical processing. It works to remove cracks and fine hard phase particles in the hard phase particles existing on the base material surface, and furthermore, adjusts the surface smoothness and composition, including the sintered surface that has not been mechanically processed. It has the function of doing.

[0029]

[Test 1] The composition was 86.0% WC-1.5.
% TiC-0.5% TiN-4.0% TaC-8.0%
Co (weight%) equivalent, the shape is CNM according to ISO standard
G120408 is a cemented carbide throwaway tip with a breaker as a base material, the boss surface is ground with a 270 # diamond grindstone, and the cutting edge is a 0.04mm radius with a nylon brush containing 320 # silicon carbide abrasive grains. After honing, the electrolyte, voltage, current,
Electrolytic treatment was performed at room temperature for a treatment time, and surface-treated base materials used for inventive products 1 to 8 and comparative product 1 shown in Table 1 were produced. Also, using the same base material, the surface-treated base material used for the comparative product 2 which was subjected to the brushing treatment containing silicon carbide abrasive grains without performing the electrolytic treatment, and the lapping after the brushing treatment also containing the silicon carbide abrasive grains. A surface-treated base material to be used for the comparative product 3 and a surface-treated base material to be used for the comparative product 4 in which the cutting edge was similarly honed with a nylon brush containing 1000 # diamond abrasive grains.

[0030]

[Table 1]

After the base material of the surface-treated throw-away tip is subjected to ultrasonic cleaning in acetone, a 1.0 μm Ti
N, 8.0 μm columnar TiCN, 1.5 μm Al ₂
Total film thickness of 11.0 μm consisting of O ₃ and 0.5 μm TiN
m to obtain surface-coated throw-away chips of inventive products 1 to 8 and comparative products 1 to 4. One of the surface-coated throw-away chips thus obtained was cut, and the cut surface was ground and wrapped with a 0.3 μm diamond paste. Then, the base material and the hard film were cut using a field emission scanning electron microscope. The vicinity of the interface was observed. The observation places are the work surface of the cutting edge and the burnt surface in the breaker. The observations included the presence or absence of cracks in the hard phase particles, the presence or absence of hard phase fine particles of 0.2 μm or less, the presence or absence of coarse irregularities of 2.0 μm or more, the hard film and the bonding phase with respect to the adhesive interface between the hard film and the hard particles. Ratio at the interface with the substrate, (W, Ti,
Ta) The presence or absence of the C phase was determined, and the results of these observations are shown in Table 2.

Next, using each of the five surface-coated throw-away tips, a work material: S45C having four grooves,
An outer peripheral intermittent turning test was performed under the conditions of cutting speed: 150 m / min, depth of cut: 2.0 mm, feed: 0.30 mm / rev, and wet type. Table 2 also shows the results such as chipping of the blade edge until the number of impacts due to intermittent cutting reaches 10,000, and film peeling (chipping) at the time when the number of impacts reached 10,000. The results of the cutting test shown in Table 2 were shown as the number of each of the five surface-coated throw-away tips by observing defects, film peeling, and normal wear.

[0033]

[Table 2]

[0034]

[Experimental test 2] The composition was 88.0% WC-2.0.
% TaC-10.0% Co (% by weight), and the base material of a cemented carbide throwaway chip having a shape of SNGN120408 according to the ISO standard is used. Grinding with a diamond whetstone,
-25 ° × 0.1 with 400 # diamond grindstone on the cutting edge
After a honing process of 0 mm, an electrolytic treatment was performed under the conditions of the product 1 of the present invention and the product 3 of the present invention described in Table 1 of Test 1. After ultrasonic cleaning of these and the chip not subjected to the electrolytic treatment in acetone, using a CVD coating apparatus, 0.5 μm of TiN, 3.5 μm of columnar crystal TiCN, and 0.5 μm of Al were used from the base material side. ₂ O ₃ , 0.5 μm T
A total thickness of 5.0 μm of iN was coated to obtain surface-coated throw-away chips of products 9 and 10 of the present invention and comparative product 5.

Observation of the thus obtained surface-coated throw-away tip with a scanning electron microscope in the same manner as in Example 1 showed that the products 9 and 10 of the present invention exhibited cracks in the hard phase particles and a hard phase of 0.2 μm or less. No particles are found,
The area ratio of the adhesive interface between the hard film and the binder phase is 0.50 to 0.5.
On the other hand, in Comparative Product 5, innumerable cracks were found in the hard phase particles and a large number of fine hard phase particles were found at the interface, and the area ratio of the adhesive interface between the hard film and the bonding phase was 0.30. there were.

Next, for each of the surface-coated throw-away tips, a work material: SCM440 (working surface shape:
Milling was carried out under the following conditions: 50 W × 200 L), cutting speed: 135 m / min, depth of cut: 2.0 mm, feed: 0.36 mm / tooth, dry type. Number of cuts on the work surface is 40
As a result of observing the cutting edge portion at the time of the pass processing, the number of thermal cracks generated on the rake face was 3 in each of the products 9 and 10 of the present invention, while that of the comparative product 5 was 5. In Comparative product 5, wear in the form of a V-groove around the thermal crack, micro chipping at the cutting edge, and film peeling at the crater on the rake face were observed.

[0037]

EXAMPLE 3 A commercially available cemented carbide solid end mill (6 mm, 2 flutes) was used as a base material, and the surface of the base material was subjected to electrolytic treatment under the conditions of the product 1 of the present invention described in Table 1 of Example 1. (Base material for product 11 of the present invention), ultrasonic cleaning in acetone together with a base material that has not been subjected to electrolytic treatment (base material for comparative product 6), and then installed in an arc ion plating apparatus,
A (Ti, Al) N film of about 3.0 μm was coated to obtain surface-coated carbide end mills of the present invention 11 and the comparative product 6. Using these, the work material: pre-hardened steel (HRC = 4
0), cutting speed: 30 m / min, depth of cut: 10 mm,
Table feed: 64 mm, feed per blade: 0.02 mm /
Groove processing test is performed under the condition of blade and wet type, cutting length is 50m
At the point of time, the flank wear width of the cutting edge was measured. At this time, the flank wear width of the product 11 of the present invention was 0.06 mm, while that of the comparative product 6 was 0.11 mm.

[0038]

[Test 4] Approximately 10φmm × 60mm commercially available
Cemented carbide for wear resistant tools (JIS B4053-19)
96 (equivalent to V30) was used as a base material, and the whole surface of the base material was subjected to rough grinding and finish grinding with 140 # and 800 # diamond grindstones to produce punches for punching. Electrolytic treatment was performed under the conditions of the invention product 1 to obtain a base material for the invention product 12. The base material for the product 12 of the present invention and the punch of the base material for the comparative product 7 not subjected to the electrolytic treatment were subjected to ultrasonic cleaning in acetone, and then 0.5 μm TiN was used from the base material side using a CVD coating apparatus. , 3.5 μm of TiCN to obtain a total film thickness of 4.0 μm, thereby obtaining surface-coated carbide punches of the present invention product 12 and the comparative product 7. Using these, a zinc steel plate having a thickness of 0.6 mm was punched out, and the number of shots until a defective product was generated due to burrs was measured. As a result, the product 12 of the present invention had about 900,000 shots, while the comparative product 7 had about 350,000 shots.

[0039]

[Test 5] Of the product 10 of the present invention and the product of comparison 5 in test 2, only the base material is commercially available. Cermet containing titanium carbonitride. Composition: 53% Ti (C, N)-
15% WC-10% TaC-5% Mo2C-1% NbC
-1% ZrC-5% Ni-10% Co (% by weight) equivalent}
The product 13 of the present invention was produced under substantially the same conditions except that
As a result of comparison and measurement in the same manner as in the test 2, the comparative relationship between the product 13 of the present invention and the comparative product 8 is as follows.
This corresponds to a contrast relationship with.

[0040]

As described above, the surface-coated sintered alloy of the present invention has less cracks in the hard phase particles on the surface of the base material than the conventional surface-coated sintered alloy. The peelability is remarkably excellent, and as a result, there is an effect that the performance such as wear resistance, chipping resistance and peel resistance as a cutting tool and the life as a wear-resistant tool are remarkably improved.
In addition, the surface-coated sintered alloy of the present invention, in addition to the above, by adjusting the height of the base material surface smoothness, the amount of the cubic structure compound and the amount of the binder phase on the base material surface, the above-mentioned effect is more enhanced It will be demonstrated even more. Furthermore, the method for producing a surface-coated sintered alloy of the present invention is characterized in that, in comparison with the conventional method of processing the base material surface by machining or electrolytic polishing, the work-affected layer on the base material surface is completely removed, and the base material surface is removed. This is an excellent method that enables from electrolytic rough polishing to electrolytic lapping-like treatment of removing cracks in the hard phase particles and improving smoothness in the above.

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Claims (12)

[Claims] 1. A base material of a cemented carbide or a sintered alloy made of cermet containing a hard phase and a binder phase, wherein at least a part of the surface of the base material is machined, and the surface of the base material is A surface-coated sintered alloy in which a hard film having a hardness higher than that of the base material is coated in one layer or two or more layers, and particles of the hard phase on the surface of the base material covered with the hard film. A surface-coated sintered alloy excellent in exfoliation resistance, in which cracks due to the machining are not present. 2. The base material is composed of tungsten carbide as a main component and carbides, nitrides of metals belonging to groups 4a, 5a and 6a of the periodic table.
The cemented carbide according to claim 1, wherein the cemented carbide is a hard phase composed of carbonitride and at least one cubic compound in the mutual solid solution, and a binder phase mainly composed of an iron group metal. Surface coated sintered alloy with excellent peel resistance. 3. The hard film is composed of 4a, 5a, 6 of the periodic table.
group a element, aluminum, silicon carbide, nitride,
Oxides and one selected from these mutual solid solutions
The surface-coated sintered alloy excellent in peeling resistance according to claim 1 or 2, wherein the surface-coated sintered alloy is formed of a single layer or a multilayer of two or more layers. 4. The surface of the base material coated with the hard film, wherein the cubic structure compound on the surface of the base material is reduced or reduced as compared with the cubic structure compound contained in the base material. The surface-coated sintered alloy excellent in peeling resistance according to claim 2 or 3, which is not contained. 5. The surface-coated sintered alloy according to claim 1, wherein the hard film is coated adjacent to the base material. 6. The surface coating with excellent peel resistance according to claim 5, wherein the surface of the base material has irregularities of less than 2.0 μm at an interface between the base material and the hard film. Binding gold. 7. The base material according to claim 5, wherein at the interface between the base material and the hard film, the particles of the hard phase present on the surface of the base material have a size exceeding 0.2 μm. A surface-coated sintered alloy excellent in the described peeling resistance. 8. An interface between the base material and the hard film,
The area ratio of the bonding interface between the bonding phase and the hard film in the base material to the bonding interface between the hard phase and the hard film in the base material is 0.4 to 0.8. The surface-coated sintered alloy according to any one of the above items 7, which is excellent in peeling resistance. 9. A first step of machining a surface of at least a part of a cemented carbide or cermet sintered alloy base material containing a hard phase and a binder phase, and after the machining, the base material surface is made alkaline. A second step of electropolishing in the electrolytic solution of the above, and removing the machining-damaged layer remaining on the surface of the base material by the mechanical processing; and And a third step of coating a hard film having a high hardness on one or two or more laminated layers. 10. The electrolyte comprises a solution containing a hydroxide containing at least one Group 1a element of the periodic table and a ferricyan salt, a nitrite containing at least one Group 1a element of the Periodic Table, 10. The method for producing a surface-coated sintered alloy having excellent peeling resistance according to claim 9, comprising at least one selected from solutions containing sulfites, phosphites, and carbonates. 11. The surface excellent in peeling resistance according to claim 9, wherein said machining comprises at least one of grinding wheel grinding, brush grinding, lapping, blasting, and ultrasonic machining. Manufacturing method of coated sintered alloy. 12. The surface-coated sintered alloy according to claim 9, wherein said hard film is coated by a chemical vapor deposition method and / or a physical vapor deposition method. Manufacturing method.