JP2006150506A - Surface coated member and cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface coated member high in hardness and toughness and excellent in defective resistance and abrasion resistance. <P>SOLUTION: This surface coated member 5 is furnished with a hard coating layer 4 having a part with at least an under layer 1, a connecting part 3 and an upper layer 2 sequentially and continuously laminated on a surface of a base body, and a tripe type contrast 3a can be observed on the connecting part 3 in a transmission electron microscope photograph for a cross-section of the hard coating layer 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface-coated member having a hard coating layer formed on a surface thereof, and more particularly to a surface-coated cutting tool having excellent chipping resistance and chipping resistance.

Conventionally, cutting tools widely used for metal cutting are titanium carbide (TiC) layers, titanium nitride (TiN) layers, titanium carbonitride (TiCN) layers on the surface of substrates such as cemented carbides, cermets, and ceramics. ) And a surface-coated cutting tool in which a plurality of hard coating layers such as an aluminum oxide (Al ₂ O ₃ ) layer are formed.

  In such surface-coated cutting tools, in accordance with recent high-efficiency cutting, heavy impacts such as heavy interrupted cutting of metals are used under severe cutting conditions where the cutting blade is applied. In conventional tools, The hard coating layer cannot withstand the large impacts that occur suddenly, and the base is exposed due to chipping or peeling of the hard coating layer, which triggers a large chipping or abnormal wear on the cutting edge. There was a problem that the life could not be extended.

Therefore, in Patent Document 1, in a structure in which a bonding portion (strengthening layer) is arranged on a lower layer (TiCN layer) and an upper layer (Al ₂ O ₃ layer) is laminated, the reinforcing layer and the Al ₂ O ₃ layer are interposed. It is described that peeling of the Al ₂ O ₃ layer can be suppressed by applying predetermined irregularities.

Further, in Patent Document 2, the lattice pattern of the lower layer (TiCN layer), the coupling portion, and the upper layer (Al ₂ O ₃ layer) is continuous, and further has an epitaxial relationship, so that the TiCN layer-Al ₂ O ₃ layer It is described that an Al ₂ O ₃ layer having high adhesiveness and excellent mechanical strength can be produced.
Japanese Patent Laid-Open No. 11-229144 JP-A-10-156606

  However, even with the configuration of the hard coating layer described in Patent Document 1, the hard coating layer cannot withstand the impact and is large in the coating layer in cutting where a sudden large impact such as heavy interrupted cutting is applied. Cracks occurred, abnormal wear due to chipping of the cutting edge, sudden breakage, etc., and tool life was shortened. Further, even when cutting steel or the like, further improvement in fracture resistance and wear resistance has been demanded.

In addition, in a hard layer having an epitaxial relationship between the lower layer (TiCN layer) and the upper layer (Al ₂ O ₃ layer) as in Patent Document 2, the adhesion between layers is improved, but the durability against a large impact is reduced. There was a problem of doing.

  Therefore, the present invention has been made to solve the above-mentioned problems, and its purpose is to increase durability against impact, and has excellent chipping resistance and chipping resistance without occurrence of chipping or chipping, An object of the present invention is to provide a surface covering member such as a long-life cutting tool having excellent wear resistance.

  As a result of studying the above problems, the present inventor has found that at least a part of the joint between the lower layer and the upper layer in the hard coating layer having a structure in which three or more multilayer films are laminated on the surface of the substrate. As a result of having a structure having a stripe-like contrast (hereinafter abbreviated as a stripe structure), the joint can absorb the impact even if an impact is applied from the surface of the hard coating layer during processing. It was found that the fracture resistance of the steel was improved.

  That is, the surface coating member of the present invention is a surface coating member comprising a hard coating layer having a portion in which at least a lower layer, a bonding portion, and an upper layer are sequentially laminated on the surface of the substrate, In a transmission electron micrograph of a cross section of the hard coating layer, stripe-like contrast extending in a direction perpendicular to the substrate surface is observed in at least a part of the coupling portion. .

  Here, it is desirable that the bonding portion is in a state where projecting particles extending from the lower layer toward the upper layer are scattered in order to increase the interlayer adhesion between the lower layer and the upper layer.

  In addition, it is desirable that the protruding particles have a corundum structure because the impact resistance can be further improved.

Here, the lower layer is a TiCN layer made of streaks grown perpendicularly to the substrate surface, and the protruding particles are (Ti _v Al _1-v ) C _x N _y O _z S _w (x + y + z + w = 1, 0 ≦ v ≦ 1, 0 ≦ w ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1), and it is high that the upper layer is an Al ₂ O ₃ layer It is desirable in that it can achieve wear resistance and high fracture resistance.

  Furthermore, the average particle size in the width direction of the streaky TiCN particles is 100 to 1000 nm, and the average particle size in the width direction of the TiCxNyOz protruding particles is 5 to 70 nm. Is desirable in that both can be balanced.

  In addition, it is desirable for the joint portion to have a layered joint portion with a film thickness of 0.1 to 1 μm in order to maintain high impact resistance.

  Further, in a state where the hard sphere is in contact with the surface of the surface covering member, the hard sphere is rotated so as to roll to locally wear the hard sphere contact portion of the surface covering member, and the base body is centered. When performing a calotest to form a spherically curved wear mark on the hard coating layer so as to be exposed, and observing the wear mark, a crack is generated from the interface with the joint of the upper layer toward the inside of the upper layer. Observation is desirable in terms of enhancing impact resistance.

Here, when the peeling load upper layer begins to peel from the surface of the lower layer F _U, the peeling load the lower layer begins to peel from the surface of the substrate was set to F _L, the ratio (F L _/ F _U ) is preferably from 1.1 to 30 in terms of improving hardness and toughness, and further improving wear resistance and fracture resistance without impairing practically necessary hardness.

  Furthermore, the surface covering member having the above-described configuration can be applied to various applications such as wear-resistant parts such as sliding parts and dies, cutting tools, excavation tools, tools such as blades, and impact-resistant parts. When used as a cutting tool that cuts the cutting edge formed at the intersection ridge line between the rake face and the flank surface against the workpiece, the above-mentioned excellent effects can be exhibited, and it can be used for other purposes. Even if it is used, it has excellent mechanical reliability.

  The surface-coated cutting tool according to the present invention is a hard coating layer having a structure in which three or more multilayer films are laminated on the surface of a substrate, and has a higher durability against impact on the layer between the lower layer and the upper layer. By providing a bonding layer that can be applied, even if an impact is applied from the surface of the hard coating layer during processing, the stripe structure portion of the bonding layer can absorb the impact, resulting in improved fracture resistance of the member To do.

  Therefore, for example, in the case of use of a cutting tool, even in processing where fracture resistance is required, impact can be absorbed by slight peeling between layers or generation of cracks, and large peeling or chipping of the entire coating layer can be prevented. Furthermore, even if the layers are peeled off, the adhesion of the remaining lower layer to the substrate is high, contributing to the suppression of wear and chipping, and the coating layer as a whole has high wear resistance and chipping resistance. . Further, by further optimizing the peeling load between the upper layer and the lower layer, the coating layer has high wear resistance without being peeled off in processing where wear resistance is required.

  In particular, severe cutting conditions such as heavy interrupted cutting of metal such as cast iron in which high-hardness graphite particles are dispersed such as gray cast iron (FC material) and ductile cast iron (FCD material) In continuous cutting conditions, and also in combined cutting conditions combining these intermittent cutting and continuous cutting, even if a sudden large impact is applied to the hard coating layer, a new large crack is generated and the hard coating As a result of the impact absorption without chipping or chipping of the layer, the chipping and peeling of the entire hard coating layer can be prevented, and the wear resistance of the entire hard coating layer is maintained. A cutting tool having properties can be obtained. Of course, even in steel cutting, the tool is superior in fracture resistance and wear resistance to conventional tools.

  The surface covering member of the present invention comprises a hard covering layer having a portion in which at least the lower layer 1, the bonding portion 3, and the upper layer 2 are successively laminated on the surface of the base 11, As is apparent from FIG. 1 which is an example of a transmission electron microscope (TEM) photograph of the main part of the cross section, it originates from stacking faults in the joint 3 existing between the lower layer 1 and the upper layer 2. A stripe-shaped contrast (stripe structure) 3a is observed.

  Since the coupling portion 3 includes a large number of stacking faults such that the stripe structure 3a is observed in the TEM photograph, even if an impact is applied from the surface of the hard coating layer 4 during processing, As a result of being able to absorb the impact, the fracture resistance of the surface covering member (hereinafter simply referred to as “member”) 5 is improved.

  Here, the bonding portion 3 is dotted with the protruding particles 6 of fine columnar crystals from the lower layer 1 into the upper layer 2 to improve the interlayer adhesion between the lower layer 1 and the upper layer 2. Is desirable. Note that the direction of the stripe structure 3a preferably extends so as to be parallel to the protruding direction of the protruding particles 6, that is, not parallel to the surface of the substrate 11, but toward the surface of the hard coating layer 4. It is desirable that it is stretched to effectively absorb the impact.

  In addition, it is desirable that the protruding particles 6 have a corundum structure having a long c-axis length in the stripe structure 3a in terms of further improving impact resistance. The structure of the stripe structure 3a basically includes a structure having a corundum structure. For example, the stripe structure 3a may have a crystal structure similar to a BaAlOx compound.

Furthermore, the lower layer 1 is a TiCN layer 7 made of streaks grown perpendicular to the surface of the substrate (not shown in the TEM photograph of FIG. 1), and the protruding particles 6 are (Ti _v Al _1-v ). C _x N _y O _z S _w (x + y + z + w = 1, 0 ≦ v ≦ 1, 0 ≦ w ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) 8 and upper layer 2 Is an Al ₂ O ₃ layer 9 from the viewpoint of achieving high wear resistance and high fracture resistance.

  The coupling portion 3 may be layered. However, as described above, the structure in which the protruding particles 6 are scattered in addition to the layered structure portion 8 prevents cracks due to impact and the like, and is more resistant to shock. It is desirable in terms of superiority. Further, the connecting portion 3 may be composed only of the protruding particles 6.

Here, it is desirable that the Al ₂ O ₃ layer 9 has an α-type crystal structure because it is structurally stable and can maintain excellent wear resistance even at high temperatures. Conventionally, Al ₂ O ₃ having an α-type crystal structure has excellent wear resistance. However, since the particle size at the time of nucleation is large, the contact area with the TiCN layer 7 is reduced, and the adhesion is weakened. As a result, there is a problem that film peeling is likely to occur. However, it is possible to control the adhesion between the Al ₂ O ₃ layer 9 and the TiCN layer 7 by the organization adjusted as described above within a predetermined range, with even enough to the Al ₂ O ₃ layer 9 as α-type crystal structure It is possible to gain strength. Therefore, the excellent wear resistance of Al ₂ O ₃ having the α-type crystal structure can be obtained without reducing the adhesion of the Al ₂ O ₃ layer 4, so that the life of the member 5 can be further extended. it can.

Incidentally, Al ₂ a part of Al ₂ O ₃ crystal as a κ-type crystal structure other than α-type crystal structure, i.e. the crystal structure of the Al ₂ O ₃ layer 4 as mixed crystals of α-type crystal structure and κ-type crystal structure It is also possible to adjust the adhesion of the O ₃ layer 9. When the Al ₂ O ₃ layer 9 has an α-type crystal structure, the layered joint 8 of the joint 3 is TiC _x N _y O _z (x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1). , 0 ≦ z ≦ 1), and in particular, z ≧ 0.1 is desirable in that the α-type crystal structure can be grown stably.

  On the other hand, the TiCN particles 10 having a streak structure extending perpendicularly to the surface of the substrate 11 have a crystal structure in a direction perpendicular to the interface with the substrate 11 / average crystal width = a crystal structure having an aspect ratio of 2 or more. Point to. Moreover, in cross-sectional structure observation of the hard coating layer 5 as shown in FIG. 3 (FIG. 3 is a scanning electron microscope (SEM) photograph), it is a mixed crystal in which granular TiCN crystals are mixed at a ratio of 30 area% or less. Also good.

Further, the average particle diameter w _{1 in} the width direction of the streaky TiCN particles 10 forming the TiCN layer 7 is 0.1 to ₁ μm, and the contrast width w _{2 in} the width direction of the protruding particles 6 is 5 to 70 nm. However, it is desirable in terms of achieving a balance between interlayer adhesion and impact resistance.

  In the present invention, as a method of measuring the average crystal width seen from the cross-sectional direction of the TiCN particles 10 made of streak-like crystals and the stripe width seen from the cross-sectional direction of the protruding particles, a cross section including the hard coating layer 3 is scanned. From the scanning electron microscope (SEM) photograph (FIG. 3) or the transmission electron microscope (TEM) photograph (FIG. 1), a straight line parallel to the interface between the substrate 11 and the hard coating layer 4 is drawn in each layer (the line segment in FIG. 3). A and B), the average value of the width of each particle on this line segment, that is, the value w divided by the number of grain boundaries crossing the line segment with respect to the line segment length.

  The layered joint 8 of the joint 3 is composed of at least one of TiCN, TiC, TiCO, TiNO, and TiCNO, and may be two or more. Further, the height region of the joint portion 3 (when the joint portion 3 is made of protruding particles, the average particle diameter in the height direction of the hard coating layer 3, and when the joint portion 3 is made only of the layered joint portion 8, In order to maintain high impact resistance, it is desirable that the total thickness of the film thickness and the total when including both is 0.1 to 1 μm. In addition, when the layered coupling | bond part 8 consists of a multilayer, as for the film thickness of the layered coupling | bond part 8, it is desirable that the total film thickness is 0.1-1 micrometer.

  Further, as shown in FIG. 2, the hard sphere 12 is rotated so that the hard sphere 12 is rolled in a state where the hard sphere 12 is in contact with the surface of the member 5, and the hard sphere 12 contact portion of the member 5 is locally worn. Then, a calotest is performed to form a spherical curved wear mark on the hard coating layer 5 so that the base 11 is exposed. In the observation of the wear mark of this calotest, the upper layer 2 is connected to the inside of the upper layer 2 from the interface with the joint 3. From the viewpoint of improving the impact resistance, it is desirable that cracks are observed.

  If the size of the exposed substrate 2 is too large or too small, cracks in the hard coating layer 4 may not be observed accurately, so the diameter of the substrate 11 exposed in the wear scar is small. It is preferable to adjust the wear conditions (time, type of hard sphere, abrasive, etc.) of the calo test so that the diameter of the entire wear scar is 0.1 to 0.6 times.

Here, when the upper layer 2 is a peel load begins to peel from the surface of the lower layer 1 F _U, the peeling load lower layer 1 starts to peel from the surface of the substrate 11 was set to F _L, the ratio (F L _/ F _U ) is preferably from 1.1 to 30 in terms of improving hardness and toughness, and further improving wear resistance and fracture resistance without impairing practically necessary hardness.

The base 11 of the member 5 is composed of tungsten carbide (WC) and, if desired, a hard phase comprising at least one selected from the group consisting of carbides, nitrides, and carbonitrides of Group 4a, 5a, and 6a metals of the periodic table. Cemented carbide in which a binder phase composed of an iron group metal such as cobalt (Co) and / or nickel (Ni) is bonded, Ti-based cermet, Si ₃ N ₄ , Al ₂ O ₃ , diamond, cubic crystal Any of ceramics such as boron nitride (cBN) can be suitably used. Among them, when used as a cutting tool, it is desirable that it is made of cemented carbide or cermet in terms of fracture resistance and wear resistance. Further, the substrate 11 may be made of a metal such as carbon steel, high-speed steel, or alloy steel depending on the application.

Further, at least one layer selected from the group consisting of a TiN layer, a TiC layer, a TiCNO layer, a TiCO layer, and a TiNO layer (other Ti-based layers) is provided between the TiCN layer 7 and the substrate 11 and on the Al ₂ O ₃ layer 9. It is desirable to form a coating layer. Here, by forming the other Ti-based coating layer as a base layer between the TiCN layer 7 and the substrate 11, the effect of suppressing the diffusion of the substrate component and the effect of easily controlling the crystal structure of the TiCN layer 9 There is. Further, by forming the other Ti-based coating layer as a surface layer on the surface of the Al ₂ O ₃ layer 9, it is possible to adjust the slidability, appearance, and the like of the coating layer surface.

At this time, by forming the surface layer 16 made of the TiN layer on the upper layer of the Al ₂ O ₃ film 4, that is, the surface of the hard coating film 3, the tool exhibits a gold color. It is desirable because it is easy to determine whether it has been worn and used, and the progress of wear can be easily confirmed. Furthermore, the surface layer 12 is not limited to a TiN layer, and a DLC (diamond-like carbon) layer or a CrN layer may be formed in order to improve slidability. The film thickness of the TiN layer constituting the surface layer 16 is preferably 1 μm or less, and the peel strength of the surface layer 16 is lower than the peel strength of the Al ₂ O ₃ film 9, which makes it easy to visually confirm whether or not it is used. Desirable in terms.

  Furthermore, the surface covering member 5 having the above-described configuration can be applied to various uses such as sliding parts, wear-resistant parts such as dies, cutting tools, tools such as excavation tools, blades, and impact-resistant parts. When used as a cutting tool, the above-described excellent effects can be exhibited, and even when used for other purposes, it has excellent mechanical reliability.

(Production method)
Moreover, the method to manufacture the surface covering cutting tool mentioned above which is an example of the surface covering member of this invention is demonstrated.

  First, metal powder, carbon powder, etc. are appropriately added to and mixed with inorganic powders such as metal carbides, nitrides, carbonitrides, and oxides that can be formed by firing the hard alloy described above, press molding, cast molding, After forming into a predetermined tool shape by a known forming method such as extrusion molding or cold isostatic pressing, the substrate 2 made of the above-described hard alloy is produced by firing in a vacuum or non-oxidizing atmosphere. . Then, the surface of the base 2 is subjected to polishing or honing of the cutting edge as desired.

  The surface roughness of the substrate 2 is such that the arithmetic average roughness (Ra) on the rake face is 0.1 to 1.5 μm and the arithmetic average roughness (Ra) on the flank face is that the adhesion force of the coating layer is controlled. The particle size, the forming method, the firing method, and the processing method of the raw material powder are controlled so that the value becomes 0.5 to 3.0 μm.

  Next, the coating layer 5 is formed on the surface by, for example, chemical vapor deposition (CVD).

First, as a reaction gas composition, a mixed gas composed of 0.1 to 10% by volume of titanium chloride (TiCl ₄ ) gas, 10 to 60% by volume of nitrogen (N ₂ ) gas, and the balance of hydrogen (H ₂ ) gas is prepared. Then, it is introduced into the reaction chamber, and a TiN layer as a base layer is formed in the chamber under conditions of 800 to 1000 ° C. and 10 to 30 kPa.

Next, as a reaction gas composition, titanium chloride (TiCl ₄ ) gas is 0.1 to 10% by volume, nitrogen (N ₂ ) gas is 0 to 60% by volume, and acetonitrile (CH ₃ CN) gas is 0.1% by volume. A mixed gas consisting of 1 to 0.4% by volume and the remainder consisting of hydrogen (H ₂ ) gas is prepared and introduced into the reaction chamber, and a TiCN layer is formed at a film formation temperature of 780 to 880 ° C. and 5 to 25 kPa. To do.

  Here, the structure of the streak-like TiCN particles 10 in the TiCN layer 7 has been described above by adjusting the ratio of acetonitrile gas in the reaction gas to 0.1 to 0.4% by volume among the above film forming conditions. Can grow reliably to range. Also, the film forming temperature is preferably 780 ° C. to 880 ° C. because the TiCN layer 7 forming fine streaks can be formed in the cross-sectional observation.

In this embodiment, the TiCN layer is formed late (TiCN superstructure) rather than the proportion of CH ₃ CN in the reaction gas used in the first stage of TiCN film formation (TiCN substructure). By increasing the mixing ratio of acetonitrile (CH ₃ CN) gas in the reaction gas used for the above, the average crystal width of TiCN particles in the TiCN upper structure is made larger than that in the TiCN lower structure. Specifically, reliable control is possible by setting the ratio of acetonitrile gas introduced at the later stage of TiCN layer deposition to 1.5 times or more of the ratio of acetonitrile gas introduced at the first stage of TiCN layer deposition. It is.

Here, among the film forming conditions, in the growth process of the streak TiCN crystal, the CH ₃ CN (acetonitrile) gas ratio V _A is controlled to 0.1 to 3% by volume and the carrier gas H ₂ gas is used. By controlling the concentration to be low so that the ratio (V _A / V _H ) of the ratio V _H to the CH ₃ CN gas ratio _VA is 0.03 or less, fine nucleation can be achieved and the TiCN layer Adhesion can be improved.

When forming the upper structure of the TiCN layer, the amount of CH ₃ CN gas introduced into the reaction gas is changed as described above, and the film formation temperature is adjusted as desired, so that the average crystal width of the TiCN crystal is increased. It is possible to control to a predetermined configuration.

Next, a bonding portion is formed. In order to form the bonding part 11, titanium chloride (TiCl ₄ ) gas is 0.1 to 3% by volume, methane (CH ₄ ) gas is 0.1 to 10% by volume, and carbon dioxide (CO ₂ ) gas is 0%. 0.1 to 5% by volume, nitrogen (N ₂ ) gas in an amount of 0 to 60% by volume, and the remaining mixed gas consisting of hydrogen (H ₂ ) gas was prepared and introduced into the reaction chamber. 5-30 kPa. At this time, according to this embodiment, the film forming apparatus is adjusted so that the temperature of the surface of the substrate 11 formed at the time of forming the coupling portion is 20 to 80 ° C. higher than the temperature of the mixed gas to be formed. Thus, a predetermined stripe structure can be introduced into the intermediate portion.

Subsequently, an Al ₂ O ₃ layer 4 is formed. As a method of forming the Al ₂ O ₃ layer 4, aluminum chloride (AlCl ₃ ) gas is 3 to 20% by volume, hydrogen chloride (HCl) gas is 0.5 to 3.5% by volume, carbon dioxide (CO ₂ ). Using a mixed gas composed of 0.01 to 5.0% by volume of gas, 0 to 0.5% by volume of hydrogen sulfide (H ₂ S) gas, and the remainder of hydrogen (H ₂ ) gas, 950 to 1100 ° C., 5 It is desirable to set it to 10 kPa.

Further, in order to form the surface layer (TiN layer) 12, the reaction gas composition is 0.1 to 10% by volume of titanium chloride (TiCl ₄ ) gas, 0 to 60% by volume of nitrogen (N ₂ ) gas, and the rest A mixed gas composed of hydrogen (H ₂ ) gas may be adjusted and introduced into the reaction chamber, and the inside of the chamber may be set to 800 to 1100 ° C. and 50 to 85 kPa.

  At this time, in addition to the above-described method, the upper layer 5 and the lower layer 5 are formed by controlling the cooling rate of the chamber up to 700 ° C. to 12 to 30 ° C./min after forming the coating layer 4 by the chemical vapor deposition method. The adhesion force of the layer 4 can be controlled within the predetermined range described above.

  Then, if desired, at least the cutting edge portion on the surface of the formed coating layer 3 is polished. By this polishing process, the residual stress remaining in the coating layer 3 at the cutting edge portion is released, and the tool is further excellent in fracture resistance.

  In addition, this invention is not limited to the said embodiment, For example, one part or all part of the coating layer may be formed by the physical vapor deposition (PVD) method.

  6% by mass of metallic cobalt (Co) powder with an average particle size of 1.2 μm and 0% of titanium carbide (TiC) powder with an average particle size of 2.0 μm with respect to tungsten carbide (WC) powder with an average particle size of 1.5 μm. .5% by mass, TaC powder was added and mixed at a rate of 5% by mass, formed into a cutting tool shape (CNMA120204) by press molding, and then subjected to binder removal treatment at 1500 ° C. in a vacuum of 0.01 Pa. A cemented carbide was prepared by firing for 1 hour. Further, the prepared cemented carbide was subjected to cutting edge processing (Honing R) on the rake face side by brushing. The arithmetic average roughness (Ra) according to JISB0601-2001 on the flank face of the obtained substrate was 1.1 μm, and the arithmetic average roughness (Ra) on the rake face was 0.4 μm.

Next, various coating layers were formed on the cemented carbide by the CVD method under the film formation conditions and film configurations shown in Tables 1 and 2. Then, the surface of the coating layer was brushed for 30 seconds from the rake face side, and sample No. 1 to 7 surface-coated cutting tools were prepared. Note that the temperature of the substrate when forming the bonding portion was constant at 1020 ° C.

About the obtained tool, it grind | polished so that the coating layer described in Table 2 could be observed using a transmission electron microscope (TEM), the micro structure state seen from the cross-sectional direction of each layer was observed, and the state of a joint part The presence or absence of protruding particles and the width thereof were observed. Also, a scanning electron microscope (SEM) photograph was taken at five arbitrary fractured surfaces including the cross section of the coating layer, and the structure of the TiCN layer, the bonding portion, and the Al ₂ O ₃ layer was observed in each photograph, and five photographs were taken. The average value of the crystal widths calculated for each was calculated.

  Moreover, the crack state of the hard coating layer of the said surface coating cutting tool was observed with the metal microscope or SEM for the abrasion trace produced by the Calotest test performed on the following conditions, and the presence or absence of a crack and the advancing direction were measured, respectively. The results are shown in Table 2.

Equipment: CSEM-CALOTEST manufactured by Nanotech
Steel balls 30 mm diameter spherical steel balls Diamond paste 1/4 MICRON
Further, the substrate is exposed so that the diameter of the substrate exposed in the wear mark is 0.1 to 0.6 times the diameter of the entire wear mark (0.3 to 0.7 mm in this measurement). The cracks were observed.

  Moreover, the adhesive force of the hard coating layer was measured by a scratch test under the following conditions. The results are shown in Table 2.

Apparatus: CSEM-REVETEST manufactured by Nanotech
Measurement conditions Table speed: 0.17 mm / sec
Load speed 100N / min
Indenter Conical diamond indenter (Diamond contactor manufactured by Tokyo Diamond Tool Mfg. Co., Ltd .: N2-1487)
Curvature radius: 0.2mm
Ridge angle: 120 °
The results are shown in Table 2.

  Then, using this cutting tool, a continuous cutting test and an intermittent cutting test were performed under the following conditions to evaluate the wear resistance and fracture resistance.

(Continuous cutting conditions)
Work material: Ductile cast iron 4-slot sleeve material (FCD700)
Tool shape: CNMA120204
Cutting speed: 250 m / min Feed speed: 0.4 mm / rev
Cutting depth: 2.5mm
Cutting time: 25 minutes Others: Use of water-soluble cutting fluid Evaluation item: Observe the cutting edge with a microscope and measure the amount of flank wear and tip wear (intermittent cutting conditions)
Work material: Ductile cast iron 4-slot sleeve material (FCD700)
Tool shape: CNMA120204
Cutting speed: 250 m / min Feeding speed: 0.3 to 0.5 mm / rev
Cutting depth: 2.5mm
Other: Use of water-soluble cutting fluid Evaluation item: Number of impacts leading to breakage
Table 3 shows the results of observing the peeling state of the coating layer of the cutting edge with a microscope at the time of impact of 1200 times.

  From Tables 1 to 3, sample no. In Nos. 5 and 6, chipping occurred and the chipping resistance was poor.

  On the other hand, according to the present invention, Samples 1 to 4 in which lattice defects exist in the joint portion have a long life both in continuous cutting and intermittent cutting, and have excellent cutting performance in both chipping resistance and chipping resistance. I had it.

It is a transmission electron microscope (TEM) photograph about the principal part of the hard coating layer of the surface coating member of this invention. It is a schematic diagram of the Calotest evaluated about the surface covering member of this invention. It is a scanning electron microscope (SEM) photograph about the principal part of the hard coating layer of the surface coating member of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower layer 2 Upper layer 3 Joint part 3a Stripe structure 4 Hard coating layer 5 Surface coating member (member)
6 Protruding particles 7 TiCN layer 8 Layered joint 9 Al ₂ O ₃ layer 10 Streaked TiCN particles 11 Base 12 Hard sphere w ₁ Average crystal width of TiCN layer w ₂ Average stripe width of protruding particles 15 Underlayer 16 Surface layer

Claims (9)

A surface coating member comprising a hard coating layer having a portion in which at least a lower layer, a bonding portion, and an upper layer are sequentially laminated on the surface of a substrate, and in the cross-sectional structure observation of the hard coating layer, A surface covering member having a stripe-like contrast in at least a part of a coupling portion. The portion having the stripe-like contrast of the coupling portion is observed in protruding particles extending from the lower layer toward the upper layer, and the protruding particles are scattered. Surface covering member. The surface covering member according to claim 2, wherein the protruding particles have a corundum structure. The lower layer is a TiCN layer made of streaks grown perpendicular to the substrate surface, and the protruding particles are (Ti _v Al _1-v ) C _x N _y O _z S _w (x + y + z + w = 1, 0) 4... ≦ v ≦ 1, 0 ≦ w ≦ 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1), and the upper layer is an Al ₂ O ₃ layer. A surface covering member as described above. The surface covering member according to claim 4, wherein an average particle size in the width direction of the streaky TiCN particles is 0.1 to 1 µm, and an average contrast width in the width direction of the protruding particles is 5 to 70 nm. The surface covering member according to any one of claims 1 to 5, wherein the bonding portion has a configuration in which a layered bonding portion having a layer thickness of 0.1 to 1 µm and the protruding particles are sequentially laminated. With the hard sphere in contact with the surface of the surface covering member, the hard sphere is rotated so as to roll to locally wear the hard sphere contact portion of the surface covering member, and the base body is exposed at the center. Thus, when performing a calotest to form a spherical curved wear mark on the hard coating layer and observing the wear mark, cracks are observed from the interface with the joint of the upper layer toward the inside of the upper layer. The surface covering member according to claim 1. The upper layer is peeled off load the F _U begins to peel from the surface of the lower _layer, when the peeling load the lower layer begins to peel from the surface of the substrate was set to F _L, the ratio _(F L _/ F _U) are It is 1.1-30, The surface covering member in any one of Claims 1 thru | or 7. A cutting tool comprising the surface covering member according to claim 1.

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