JP5328653B2 - Ti-based cermet, coated cermet and cutting tool - Google Patents

Description

  The present invention relates to a Ti-based cermet, a coated cermet, and a cutting tool, and more particularly to a cutting tool having improved wear resistance in a cutting edge.

  Currently, as a member that requires wear resistance, slidability, and fracture resistance, such as cutting tools, wear-resistant members, sliding members, cemented carbides mainly composed of WC, Ti-based cermets mainly composed of Ti, etc. Sintered alloys are widely used. For these sintered alloys, new compositions are being developed to improve their performance.

  For example, Patent Document 1 discloses a technique for forming a cemented carbide or cermet by reactive sintering using microwaves, and adding Mn or Al to a bonded metal phase such as Co at a ratio of 5% by mass or less. Is described.

Moreover, in patent document 2, in addition to the hard phase which has as a main component the carbide | carbonized_material, nitride, and these mutual solid solution of periodic table 4, 5 and 6 metal, and 1-40 mass% iron group metal, A graded composition sintered alloy to which 0.1 to 10% by mass of a specific metal element such as Mn is added is disclosed. Sample numbers 17 and 20 in Table 6 describe Ti-based cermets to which Mn is added. In Table 8, it is described that the Mn concentration and the binder phase concentration in the sample numbers 17 and 20 are increased inside the surface of the cermet.
Special Table 2000-503344 JP 2004-292905 A

  However, the method of adding Mn and performing the microwave firing as in Patent Document 1 has limitations in improving the hardness and toughness of the cermet. In addition, even with the gradient composition in which the Mn concentration and the binder phase concentration in the sintered body are increased as in Patent Document 2, the effect of improving the hardness on the surface of the cermet is not sufficient, and the cutting edge cuts the workpiece. When the materials are welded, there is a problem that the finished surface of the work material is roughened and abnormal wear or chipping occurs.

  Therefore, the cutting tool of the present invention is for solving the above-mentioned problems, and its purpose is to improve the wear resistance and welding resistance of the Ti-based cermet.

The Ti-based cermet of the present invention is at least one of Co and Ni, and one or more of carbides, nitrides and carbonitrides of Periodic Tables 4, 5, and 6 metals mainly composed of Ti In the scanning electron microscope (SEM) photograph of an arbitrary cross section composed of the above and 0.1 to 0.5% by mass of Mn, the inside is made of TiCN, or TiCN and Co and / or Ni From the nitride or carbonitride of the periodic table group 4, 5 and 6 metal which contains Ti, and contains the periodic table group 4, 5, and 6 metal other than Ti as essential components And a hard phase consisting of at least one binder phase of Co and Ni is observed, and the second hard phase is observed in the surface portion at a content ratio of 90 area% or more. The surface area is also formed It is.

Further, the Ti-based cermet manufacturing method of the present invention includes at least TiCN powder and carbide powder, nitride powder, or carbonitride powder containing at least one of W, Mo, Ta, V, Zr, and Nb. After molding a mixed powder obtained by mixing one type, at least one type of powder of Co and Ni, and metal Mn powder or Mn compound powder in a total amount of 0.2 to 3.0% by mass in terms of Mn, (a The temperature is raised from room temperature to 1200 ° C. in a vacuum, and (b) the temperature is raised from 1200 ° C. to a firing temperature T ₁ of 1330 to 1380 ° C. at a rate of 0.1 to 2 ° C./min. (C) In an inert gas atmosphere of 30 to 2000 Pa, the temperature is raised at a heating rate of 4 to 15 ° C./min from a firing temperature T ₁ to a firing temperature T _{2 of} 1450 to 1600 ° C., and (d) 30 to In an inert gas atmosphere of 2000 Pa, And held at formation temperature _{T 2} 0.5 to 2 hours, which is then burned in a condition of temperature decrease (e).

  Furthermore, the coated cermet of the present invention is a coated cermet in which the surface of the substrate is coated with a coating layer using the Ti-based cermet as a substrate, and the content ratio of the binder phase in the surface region of the substrate is 3% by mass. In addition to the following, the coating layer is formed by a chemical vapor deposition method.

The cutting tool of the present invention is made of the Ti-based cermet or the coated cermet, and has a cutting edge formed at the crossing ridge line portion between the rake face and the flank face. The residual stress in the σ ₁₁ direction (direction connecting the center of the rake face and the center of the cutting edge closest to the measurement point) measured by the 2D method on the rake face is the compressive stress of the second hard phase. It is desirable that the pressure be 150 MPa or more (σ ₁₁ ≦ −150 MPa).

  According to the Ti-based cermet of the present invention, 0.1 to 0.5 mass% of Mn is contained, and a surface region in which the second hard phase is observed at a content ratio of 90 area% or more is formed on the surface of the cermet. Therefore, the toughness of the cermet as a whole is high, the hardness on the surface of the cermet is increased, the wear resistance is improved, and the welding resistance can be increased.

(Ti-based cermet)
An example of the Ti-based cermet of the present invention will be described based on a scanning electron microscope (SEM) photograph of a cross-sectional main part including the surface region of the Ti-based cermet of FIG.

  A Ti-based cermet (hereinafter simply abbreviated as cermet) 1 in FIG. 1 is at least one of Co and Ni, and one or more carbides of Group 4, 5, and 6 metals in the periodic table mainly containing Ti. And one or more of nitrides and carbonitrides and 0.1 to 0.5% by mass of Mn.

  As shown in FIG. 1, in a scanning electron microscope (SEM) photograph of an arbitrary cross section, a hard phase 2 consisting of a black first hard phase 2a and an off-white second hard phase 2b, mainly Co and At least one binder phase 3 of Ni is observed, and a surface region 5 where the content ratio of the second hard phase 2b is observed at 90 area% or more is formed on the surface portion.

  As a result, the toughness of the cermet as a whole can be increased, the hardness on the surface of the cermet can be increased, the wear resistance can be improved, and the welding resistance can be increased.

Here, in the scanning electron microscope (SEM) photograph of the cross-sectional structure of the cermet 1 shown in FIG. 1, the first hard phase 2a is observed as black particles, and the second hard phase 2b is grayish white particles or white cores. It is observed as particles having a cored structure in which a grayish white peripheral part exists around the part. That is, the first hard phase 2a has a lighter element content ratio than the second hard phase 2b and appears black. The first hard phase 2a is either composed of TiCN, or a TiCN and Co and / or Ni, Ru Oh black particles composed of. Moreover, you may have the cored structure in which the gray-white 2nd hard phase 2b existed in the outer periphery of the 1st hard phase 2a. On the other hand, the binder phase 3 is observed as a white region, and Co and Ni constituting the binder phase 3 can be confirmed by energy dispersive spectroscopy (EMPA) attached to the scanning electron microscope (SEM).

  Here, if 0.1% by mass or more of Mn is not contained in the cermet 1, the toughness of the cermet 1 is reduced. Conversely, if more than 0.5% by mass of Mn is contained in the cermet 1, the hardness of the cermet 1 Is significantly reduced. A desirable content of Mn is 0.2 to 0.5% by mass.

Moreover, when the surface area | region 5 does not exist in the surface of the cermet 1, the hardness in the surface of the cermet 1 cannot be raised, but the abrasion resistance of the cermet 1 becomes inadequate. Furthermore, if the proportion of the second hard phase 2b present in the surface region 5 is less than 90% by area, the wear resistance and welding resistance on the surface of the cermet 1 are insufficient. A desirable thickness of the surface region 5 is 0.8 to 3 μm. Further, the preferred area ratio B _s of the second hard phase 2 b in the surface region 5 is 93 to 97 area% in terms of adhesion with the coating layer 13.

Furthermore, as shown in a scanning electron microscope (SEM) photograph in the cross section near the surface of the cermet 1 shown in FIG. 1, the average particle diameter d _1s of the second hard phase 2b is 0.5 to 3.0 μm. It is desirable that it is 1.0-2.0 micrometers. A ratio _{c s} of binder phase 3 in the surface region 5, to be 0.01 to 0.1 in a ratio _(c s / _{c i)} for the content ratio _{c i} of binder phase 3 in the interior, the cermet 1 It is desirable in that the wear resistance on the surface of the cermet 1 and the welding resistance on the surface of the cermet 1 can be enhanced.

Further, when the cross-sectional structure inside the cermet 1 is observed, the average particle size of the second hard phase 2b is larger than the average particle size of the first hard phase 2a, and preferably the average of the first hard phase 2a inside. the particle size and _{a i,} when the average particle diameter of the second hard phase 2b was _{b i,} a ratio between _{a i} and _{b i (b i / a i} ) that is 2 to 8, the second hard The phase 2b is desirable in that the thermal conductivity of the cermet 1 is improved by effectively contributing to heat propagation, and the thermal shock resistance of the cermet 1 is improved. A desirable range of the ratio (b _i / a _i ) between a _i and b _i is 3.5 to 7 in that the fracture resistance of the cermet 1 can be maintained.

  In addition, the measurement of the particle size of the hard phase 2 in this invention is measured according to the measuring method of the average particle size of the cemented carbide prescribed | regulated to CIS-019D-2005. At this time, in the case where the hard phase 2 has a cored structure, the particle diameter is measured by taking the core and the outer edge of the peripheral part including the peripheral part as one hard phase. Moreover, when observing the cross-sectional structure inside the cermet 1 in this invention, it observes in the area | region whose depth from the surface of the cermet 1 is 1000 micrometers or more.

Moreover, in the cross-sectional structure about the inside of the cermet 1, the average area of the second hard phase 2b is larger than the average area of the first hard phase 2a, and preferably the first hard phase 2a occupies the entire hard phase 2 inside. the average area and _{a i,} when the average area of the second hard phase 2b account was _{B i,} the ratio of _{a i} and _{B i (B i / a i} ) is to be 1.5 to 5, the The two hard phases 2b are desirable in that the thermal conductivity of the cermet 1 is improved by effectively contributing to heat propagation, and the thermal shock resistance of the cermet 1 is improved.

  Further, in the cermet 1, the total content ratio of the nitrides or carbonitrides of the fourth, fifth, and sixth group metals of the periodic table mainly composed of Ti forming the hard phase 2 is 70 to 96% by mass. It is desirable that the content be 85 to 96% by mass, particularly in terms of improvement in wear resistance. On the other hand, the content ratio of the binder phase 3 is preferably 4 to 30% by mass, particularly 4 to 15% by mass, and this makes the cermet 1 have an excellent balance of hardness and toughness. Moreover, as the binder phase 3, it is desirable to contain 65% by mass or more of Co with respect to the total amount of the iron group metal in order to improve the thermal shock resistance of the cutting tool. In order to maintain good sinterability of the cermet 1 so that the burned surface of the cermet 1 becomes a smooth surface, Ni is 5 to 50% by mass, particularly 10 to 10% with respect to the total amount of the iron group metal. It is desirable to make it contain in the ratio of 35 mass%.

(Coated cermet)
In addition, a coating layer can also be formed on the surface of the cermet 1. As an example, (a) a scanning electron microscope (SEM) photograph of a cross-sectional main part including the surface region of the coated cermet 10, and (b) a scanning of a main part of the polished surface before forming the coating layer of the coated cermet 10. This will be described with reference to FIG. 2 which is a scanning electron microscope (SEM) photograph.

  The coated cermet 10 in FIG. 2A has a configuration in which the surface of the substrate 12 made of the cermet 1 is coated with a coating layer 13.

  In this invention, as shown in FIG. 2, the coating layer 13 formed by the chemical vapor deposition (CVD) method can also be formed. That is, for conventional coated cermets, a physical vapor deposition (PVD) method is generally used in which the substrate is heated to about 500 ° C. The reason for this is that when the CVD method is performed in a state where the substrate is heated to a high temperature of 700 ° C. or higher, Ni or Fe used as the binder phase of the Ti-based cermet causes partial abnormal grain growth in the coating layer. This is because it may become needle-shaped, and the strength of the coating layer may be reduced to cause chipping or chipping. However, since the cermet 1 as the substrate 12 of the present invention suppresses the presence of Ni on the surface of the substrate 12, the coating layer 13 does not grow abnormally and the binding phase is not formed in the coating layer 13. 3 can be prevented from diffusing in a large amount and the hardness of the coating layer 13 from being lowered. As a result, the coating layer 13 has high hardness and high strength characteristics. Further, when the constituent components and crystal structure of the surface region 5 of the substrate 12 and the covering layer 13 are similar, the thermal expansion coefficient difference is small, so that peeling due to thermal stress occurs at the interface between the substrate 12 and the covering layer 13. There is nothing.

  And the base | substrate 12 of FIG.2 (b) has the surface area | region 5 whose content rate of the binder phase 3 is 3 mass% or less in the area | region from the surface to 0.1-5 micrometers. The covering layer 13 is formed by a CVD method. As a result, the adhesion of the coating layer 13 to the substrate 12 can be increased without reducing the hardness of the coating layer 13, so that the fracture resistance on the surface of the coated cermet 10 can be increased.

  That is, when the surface region 5 does not exist on the surface of the base body 12, Ni exists on the surface of the base body 12, and the coating layer 13 formed on the surface grows abnormally to reduce both hardness and toughness.

  Here, in the base 12, the desirable thickness of the surface region 5 is desirably 0.8 to 3 μm in order to maintain the impact resistance of the coated cermet 10. Further, the area ratio Bs of the second hard phase 2b in the surface region 5 is preferably 70 to 100% by area with respect to the entire hard phase 2 in order to improve the adhesion with the coating layer 13.

  Further, in the region from immediately below the surface region 5 to 1 to 10 μm, the content ratio A of the binder phase 3 is 1.1 to 2 in terms of the ratio (A / B) to the content ratio B of the binder phase 3 inside the substrate 12. It is desirable that a .0 bonded phase enriched region 8 be present. Thereby, even when the coating layer 13 is subjected to an impact, the binder phase enriched region 8 reduces the impact and suppresses the coating layer 13 from being chipped or chipped.

  In the coating layer 13, when the content of the binder phase 3 in the region from the surface of the substrate 12 to 0.1 to 5 μm is more than 3% by mass, the binder phase three components diffuse into the coating layer 13 and the coating layer 13. Decreases in hardness.

  Further, as the binder phase 3, in order to maintain good sinterability so that the surface of the base 12 has a smooth surface and to increase the thermal shock resistance of the base 12, the Ni content in the base 12 is contained. The ratio is preferably 0.1 to 0.5 in terms of Ni / (Ni + Co).

  Furthermore, when the content ratio of N in the surface region 5 is larger than that in the sintered body, the surface region 5 has a characteristic excellent in toughness. Therefore, when the coating layer 13 having a higher hardness than the surface region 5 is formed immediately above the surface region 5, the high hardness and brittle coating layer 13 is not chipped or peeled off even by an impact during cutting or the like. And fracture resistance can be realized. The distribution of the content ratio of N can be compared by performing X-ray photoelectron spectroscopic analysis in the depth direction from the surface to the inside of the cermet 1.

  On the other hand, the coating layer 13 is composed of columnar crystals extending in a direction perpendicular to the surface of the substrate 12 and includes a columnar crystal coating layer having an average crystal width of 0.1 to 1 μm. It is desirable in that it has high fracture resistance and is excellent in wear resistance. As the columnar crystal coating layer, a TiCN layer is desirable in that the structure can be easily produced. In this case, the coating layer may be a single layer of the columnar crystal coating layer, or the above effect can be exhibited even in a multilayer structure of one or more columnar crystal coating layers and other layers. . Further, the TiCN layer composed of the TiCN columnar crystals in the coating layer 13 has the strongest peak in the (422) plane in the X-ray diffraction measurement. This indicates that the coating layer 13 has high wear resistance and adhesion to the substrate 12. It is desirable because of its superiority.

(Cutting tools)
An example of the cutting tool of the present invention will be described with reference to FIG. 3 which is a schematic perspective view thereof.

  According to FIG. 3, the cutting tool 20 of the present invention has a rake face 21 on the main surface, a flank face 22 on the side face, and cutting edges 23 (23 a to 23 d) on the intersecting ridge line between the rake face 21 and the flank face 22. It has a configuration. According to FIG. 3, the rake face 21 is formed with a recess 25 including a breaker 24. A screw hole 26 for attaching the cutting tool 20 to a holder (not shown) is formed at the center of the rake face 21.

  And the processing method of a to-be-cut object is comprised by the following three processes. In the first step, a cutting tool 20 made of cermet 1 or coated cermet 10 and having cutting edge 23 is prepared. In the next step, the cutting edge 23 of the cutting tool 20 is brought into contact with the workpiece. In the last step, the workpiece is cut by the cutting tool 20.

According to the present invention, the residual stress applied in the σ ₁₁ direction (direction connecting the center of the rake face and the cutting edge 23a closest to the measurement point) measured by the 2D method at the portion P other than the concave portion of the rake face 21 is It is desirable that the second hard phase 2b has a compressive stress of 150 MPa or more (σ ₁₁ ≦ −150 MPa). In this way, the fracture resistance of the cutting edge 23 is improved.

(Production method)
Next, an example of the manufacturing method of the cermet mentioned above is demonstrated.

  First, TiCN powder having an average particle size of 0.1 to 2 μm, preferably 0.2 to 1.2 μm, and carbide powder, nitride powder or carbonitride of the above-mentioned other metal having an average particle size of 0.1 to 2 μm. Any one kind of powder, Co powder or Ni powder, and metal Mn powder or Mn compound powder having an average particle diameter of 0.5 to 10 μm were mixed in a total amount of 0.2 to 3.0% by mass in terms of Mn. Adjust the mixed powder.

  And a binder is added to this mixed powder, and it shape | molds in a predetermined shape by well-known shaping | molding methods, such as press molding, extrusion molding, and injection molding.

Next, according to this invention, the cermet of the predetermined structure | tissue mentioned above can be produced by baking on the following conditions. As firing conditions, (a) the temperature is raised from room temperature to 1200 ° C. in a vacuum, and (b) 0.1 to 2 ° C./minute from 1200 ° C. to a firing temperature T ₁ of 1330 to 1380 ° C. in vacuum. The temperature is raised at a temperature rising rate r ₁ , and (c) a temperature rising rate r from 4 to 15 ° C./min from a firing temperature T ₁ to a firing temperature T _{2 of} 1450 to 1600 ° C. in an inert gas atmosphere of 30 to 2000 Pa. the temperature was raised at _2, it holds the firing temperature _{T 2} at 0.5 to 2 hours in an inert gas atmosphere (d) 30~2000Pa, fired in a firing pattern that cooling (e).

That is, among the firing conditions, if the firing atmosphere in step (b) is an inert gas atmosphere rather than a vacuum, volatilization of Mn is suppressed, and the Mn content in the cermet after firing cannot be controlled and the surface region Is not formed. Further, even when the rate of temperature increase in the step (b) is made higher than 2 ° C./min, the surface region is not formed. Furthermore, when the atmosphere in step (c) is a vacuum or an inert gas atmosphere of less than 30 Pa, Mn remains in the cermet 1 in an amount of more than 0.5% by mass and the surface region is not formed. Conversely, the surface region is not formed even in a high inert gas atmosphere exceeding 2000 Pa. Further, (d) when the firing temperature T ₂ in the step is less than 1450 ° C., the above surface region is not formed, toughness because firing temperature T ₂ is 5μm or more of the surface region is formed exceeds 1600 ° C. Is inferior.

  In addition, (e) by performing the temperature lowering step in a vacuum atmosphere, the surface region 5 has high hardness and welding resistance. However, if (e) the temperature lowering step is performed in an inert gas atmosphere, N in the surface region 5 is reduced. Since the content ratio is larger than that in the cermet 1, the surface region 5 having high toughness can be formed.

Desirably, the surface of the substrate made of this cermet is coated with a coating layer at 800 to 1100 ° C. by the CVD method. To illustrate specific film formation conditions, first, in a CVD furnace, for example, titanium chloride (TiCl ₄ ) gas is 0.1 to 10% by volume, nitrogen (N ₂ ) gas is 10 to 60% by volume, and the rest is A mixed gas composed of hydrogen (H ₂ ) gas is adjusted and introduced into the reaction chamber, and the inside of the chamber is set to 800 to 1100 ° C. and 50 to 85 kPa to form a titanium nitride (TiN) layer.

Next, titanium chloride (TiCl ₄ ) is 0.5 to 5.0% by volume, acetonitrile (CH ₃ CN) is 0.3 to 1.5% by volume, nitrogen (N ₂ ) is 10 to 40% by volume, and the rest Is mixed with hydrogen (H ₂ ), and titanium carbonitride (TiN) is deposited on the titanium nitride (TiN) layer by a so-called MT-CVD method at a reaction temperature of 800 to 900 ° C. TiCN) layer is formed.

Here, the structure of the titanium carbonitride (TiCN) particles in the titanium carbonitride (TiCN) layer is adjusted to the above-described range by adjusting the ratio of acetonitrile gas in the gas within the above-described film forming conditions. It can be grown reliably. In addition, the film formation temperature is set to 800 ° C. to 850 ° C., and in the growth process of the titanium carbonitride (TiCN) crystal in the first stage of film formation of the titanium carbonitride (TiCN) layer, the ratio V _{A of} acetonitrile (CH ₃ CN) gas Is controlled to 0.3 to 1.5% by volume, and the ratio (V _A / V _H ) of the ratio V _H of the hydrogen (H ₂ ) gas as the carrier gas to the ratio V _A of the acetonitrile (CH ₃ CN) gas. ) Is controlled to a low concentration so as to be 0.03 or less, a titanium carbonitride (TiCN) layer composed of columnar crystals having an average crystal width of 0.1 to 1 μm can be formed. This TiCN layer has a film thickness of 2 μm or more and the (422) peak is the strongest in XRD diffraction.

Next, 0.1 to 3% by volume of titanium chloride (TiCl ₄ ) gas, 0.1 to 10% by volume of methane (CH ₄ ) gas, 0.01 to 5% by volume of carbon dioxide (CO ₂ ) gas, A mixed gas consisting of 0.1 to 60% by volume of nitrogen (N ₂ ) gas and the remaining hydrogen (H ₂ ) gas is adjusted and introduced into the reaction chamber, and the inside of the chamber is set to 800 to 1100 ° C. and 5 to 30 kPa. A titanium carbonitride oxide (TiCNO) layer is formed.

Then, aluminum chloride (AlCl ₃ ) gas is 3 to 20% by volume, hydrogen chloride (HCl) gas is 0.5 to 3.5% by volume, and carbon dioxide (CO ₂ ) gas is 0.01 to 5.0% by volume. Then, using a mixed gas composed of 0 to 0.01% by volume of hydrogen sulfide (H ₂ S) gas and the remaining hydrogen (H ₂ ) gas, the temperature is set to 900 to 1100 ° C. and 5 to 10 kPa, and aluminum oxide (Al ₂ O ₃ ) A layer is formed.

Further, the reaction was continued by adjusting 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 remaining hydrogen (H ₂ ) gas. A titanium nitride (TiN) layer is formed by introducing into the chamber and setting the inside of the chamber to 800 to 1100 ° C. and 50 to 85 kPa.

  Thereafter, if desired, a predetermined portion of the surface of the formed coating layer 8 is mechanically polished by a brush, an elastic grindstone, or a blast method. By this polishing process, the residual stress generated during film formation remaining in the coating layer is adjusted.

TiCN powder having an average particle diameter (d ₅₀ value) of 0.6 μm, WC powder having an average particle diameter of 1.1 μm, TiN powder having an average particle diameter of 1.5 μm, TaC powder having an average particle diameter of 2 μm as measured by the microtrack method, MoC powder with an average particle size of 1.5 μm, NbC powder with an average particle size of 1.5 μm, ZrC powder with an average particle size of 1.8 μm, VC powder with an average particle size of 1.0 μm, Ni powder with an average particle size of 2.4 μm, A mixed powder prepared by adjusting a Co powder having an average particle diameter of 1.9 μm and a MnCO ₃ powder having an average particle diameter of 5.0 μm at a ratio shown in Table 1 was mixed with isopropyl alcohol (IPA) using a stainless steel ball mill and a carbide ball. Add and wet-mix, add 3% by weight of paraffin, mix, press-mold into CNMG120408 throwaway tip tool shape at 200MPa pressure, (a) from room temperature to 12 Heated at 10 ° C. / min in vacuum to 0 ° C., (b) firing atmosphere from 1200 ° C. to a firing temperatures _{T 1} shown in Table 2 are shown in Table 2, the temperature at a heating rate _{r 1} (° C. / min) raised, after heating in (c) Table 2 shows the firing temperature T ₁ of the sintering temperature T ₂ heating rate in a firing atmosphere shown in Table 2 to r _{2 (°} C. / min), (d) Table 2 (E) The temperature was lowered in the firing atmosphere shown in Table 2 and the sample No. 1 to 11 cermet throwaway chips were obtained.

  The obtained cermet was observed with a scanning electron microscope (SEM), and image analysis was performed in a region of 8 μm × 8 μm using a commercially available image analysis software for each of the surface and the interior at a 10000 × magnification. The presence of the surface region was confirmed by observing the presence of the hard phase and the binder phase and the structure of the inside and the surface. In any sample, it was confirmed by energy dispersive spectroscopy (EMPA) accompanying the scanning electron microscope (SEM) that the binder phase was mainly composed of Co and Ni. And the average particle diameter of the hard phase in these area | regions was measured, and these ratios were computed. The results are shown in Table 3. Further, the content ratio of the metal Mn component in the cermet substrate was determined for each sample by ICP analysis. The results are shown in Table 3.

Next, the cutting test was done on the following cutting conditions using the obtained cermet cutting tool. The results are also shown in Table 3.
Work material: SCM435
Cutting speed: 200 m / min Feed: 0.20 mm / rev
Cutting depth: 1.0mm
Cutting condition: wet (use water-soluble cutting fluid)
Evaluation method: Time until the wear amount reaches 0.2 mm (minutes)

  From Tables 1-3, the sample No. which does not add Mn. In No. 8, the surface region was not formed and was worn early. Sample No. 1 having a firing temperature higher than 1600 ° C. and a Mn content of less than 0.1% by mass. In No. 10, the wear resistance deteriorated due to the occurrence of chipping. Furthermore, Sample No. in which the Mn content exceeds 0.5% by mass. No. 9 also had poor wear resistance. In addition, the sample No. in which the surface region was not formed because the firing conditions were not met. No. 11 had low wear resistance.

  On the other hand, sample no. In Nos. 1 to 7, all exhibited excellent wear resistance and good wear resistance. As a result, the tool life was long.

Sample No. For 4, 7, 11, 2D method at the rake face (apparatus: X-ray diffraction BrukerAXS Ltd. D8 DISCOVER with GADDS Super Speed, source: Cu K _alpha, collimator diameter: 0.3 mm, measuring diffraction line: TiN (422) plane ), The residual stress in the σ ₁₁ direction (the direction connecting the center of the rake face and the center of the cutting edge closest to the measurement point) is 250 MPa (σ ₁₁ = −250 MPa), 150 MPa (σ ₁₁ = −150 MPa), and 100 MPa (σ ₁₁ = −100 MPa).

  Sample No. 1 of Example 1 For the cermet throwaway chips 1 to 11, cermets were produced under the same production conditions except that the atmosphere in the temperature lowering step (e) was changed to the atmosphere shown in Table 4. The structure of the obtained cermet was observed in the same manner as in Example 1 and shown in Table 5. In addition, the N content in the cermet and the surface region are compared by performing X-ray photoelectron spectroscopic analysis in the depth direction from the sintered body surface to the inside, and the N content in the surface region / the N content in the surface region The ratios are listed in Table 6. And the coating layer of Table 6 was formed into a film on this, sample No. 12-18 throwaway chips were obtained. Using the obtained cermet throwaway tip, a cutting test was performed under the same cutting conditions as in Example 1. The results are also shown in Table 6.

  From Tables 4-6, sample no. As for any of 12-18, the surface area where the content rate of N is higher than the inside of the cermet is formed, and the throw-away tip on which the coating layer is formed exhibits excellent wear resistance. Abrasion resistance was also good.

  Conditions other than the formulation composition in Table 7 and the firing conditions in Table 8 are the same as in Example 1, and sample No. 19 to 31 cermet substrates were obtained.

  The obtained cermet substrate was observed with a scanning electron microscope (SEM), and an image analysis was performed in a region of 8 μm × 8 μm using a commercially available image analysis software for each of the surface and the interior at a 10,000 × magnification. The presence state of the hard phase and the structure state in the inside and the surface were observed, and the presence or absence of the surface region and the binder phase enriched region was confirmed. And the average particle diameter in these area | regions was measured, and these ratios were computed. Further, for each sample, the content ratio of the Mn component in the cermet substrate was determined by ICP analysis. The results are shown in Table 9.

  Next, a coating layer by the CVD method having the configuration shown in Table 11 was formed on the cermet substrate under the film forming conditions shown in Table 10. In Table 11, sample No. 1 in which a TiCN layer having a thickness of 2 μm or more was formed. For Samples 19-22 and 24, in observation with a scanning electron microscope, sample No. As shown in the photograph of No. 24, it was composed of columnar crystals having an average crystal width of 0.1 to 1 μm extending in a direction perpendicular to the surface of the cermet substrate. In all cases, the peak of the (422) plane was the strongest peak in the X-ray diffraction measurement.

Using the obtained cermet cutting tool, a cutting test was performed under the following cutting conditions. The results are also shown in Table 11.
(Abrasion resistance test)
Work material: SCM435
Cutting speed: 200 m / min Feed: 0.20 mm / rev
Cutting depth: 1.0mm
Cutting condition: wet (use water-soluble cutting fluid)
Evaluation method: Time until the wear amount reaches 0.2 mm (defect resistance test)
Work material: SCM440
Cutting speed: 100 m / min Feed: 0.05 mm / rev (0.05 mm / rev increased every 10 seconds)

Max 0.50mm / rev)
Cutting depth: 1.5mm
Cutting state: Dry evaluation method: Time measurement until the cutting edge is lost (maximum 100 seconds)

From Tables 7-11, sample No. which Ni and Mn are not added and content of Mn is less than 0.1 mass%. In No. 31, the binder phase diffused in a large amount in the coating layer, the hardness of the coating layer was lowered, and the sinterability of the cermet substrate was poor, so that chipping was likely to occur. Further, no sample Mn was added, and the sample No. In No. 28, the surface region was not formed, and abnormal needle-like grains grew in the coating layer, resulting in severe wear and defects. Further, in the step (b), the sample temperature of Sample No. No. ₁ in which the firing temperature T ₁ is higher than 1380 ° C. and the temperature increase rate r ₁ is higher than 2 ° C./min at temperatures from 1200 ° C. to 1300 to 1380 ° C. 26, Sample No. baked in vacuum in the firing atmosphere in step (d). 29, and Sample No. 2 in which the firing atmosphere in the step (e) is vacuum. No surface region was formed even at 30, and abnormal needle-like grains grew in the coating layer and both wear and defects were reduced. In addition, in the sample (No. ₁ ), the firing temperature T1 in the step (b) is lower than 1300 ° C. In No. 27, Mn exceeding 3% by mass remained in the cermet substrate after firing, and the wear resistance decreased.

  On the other hand, sample no. In 19 to 25, all exhibited excellent wear resistance and good wear resistance. As a result, the tool life was long.

It is a scanning electron microscope (SEM) photograph about the principal part cross section which shows an example of Ti-based cermet of this invention and contains a surface region. It is a scanning electron microscope (SEM) photograph about an example of a covering cermet of the present invention about a section of an important section including a surface region. It is a schematic diagram about an example of the cutting tool of this invention.

Explanation of symbols

1 Cermet (Ti-based cermet)
2 Hard Phase 2a 1st Hard Phase 2b 2nd Hard Phase 3 Bond Phase 5 Surface Area 8 Bond Phase Enriched Area 10 Covered Cermet 12 Base 13 Cover Layer 20 Cutting Tool 21 Rake Face 22 Relief Face 23 Cutting Edge 24 Breaker 25 Recess 26 Screw hole

Claims (13)

At least one of Co and Ni, one or more of carbides, nitrides and carbonitrides of Group 4, 5, and 6 metals in the periodic table mainly containing Ti, 0.1 to 0 is composed of a .5% by weight of Mn, in a scanning electron microscope (SEM) photograph of an arbitrary cross-section, and inside, or consist of TiCN, or a TiCN and Co and / or Ni, the first hard phase consisting of , containing Ti, and a second hard phase consisting of periodic table nitrides of groups 4, 5 and 6 metal or carbon nitride containing periodic table groups 4, 5 and 6 metals other than Ti as essential, from And a surface region in which at least one binder phase of Co and Ni is mainly observed and the second hard phase is observed at a content ratio of 90 area% or more is formed on the surface portion. Basic cermet.   The Ti-based cermet according to claim 1, wherein the surface region has a thickness of 0.5 to 5 μm.   Nb is dissolved in the second hard phase, and the solid solution ratio of Nb in the second hard phase in the surface region is larger than the solid solution ratio of Nb in the second hard phase inside. The Ti-based cermet according to claim 1 or 2. TiCN powder, carbide powder, nitride powder, carbonitride powder containing at least one of W, Mo, Ta, V, Zr and Nb, and at least one powder of Co and Ni And a mixed powder obtained by mixing metal Mn powder or Mn compound powder with a total amount of 0.2 to 3.0% by mass in terms of Mn, and then (a) raising the temperature from room temperature to 1200 ° C. in a vacuum. (B) The temperature is raised from 1200 ° C. to a firing temperature T ₁ of 1330 to 1380 ° C. in a vacuum at a rate of temperature rise of 0.1 to 2 ° C./min, and (c) in an inert gas atmosphere of 30 to 2000 Pa At a heating rate of 4 to 15 ° C./min from a firing temperature T ₁ to a firing temperature T _{2 of} 1450 to 1600 ° C., and (d) the firing temperature T in an inert gas atmosphere of 30 to 2000 Pa. _{2 for} 0.5-2 hours, (e) A method for producing a Ti-based cermet that is fired under a temperature lowering condition.   A coated cermet wherein the Ti-based cermet according to any one of claims 1 to 3 is used as a substrate and the surface of the substrate is coated with a coating layer, and the content ratio of the binder phase in the surface region of the substrate is 3% by mass. The coating cermet is as follows, and the coating layer is formed by a chemical vapor deposition method. In the region from immediately below the surface region to 1 to 10 μm, the binder phase content ratio A is 1.1 to 2.0 in the ratio (A / B) to the binder phase content ratio B inside the substrate. The coated cermet according to claim 5, wherein a phase-enriched region is present.   The coated cermet according to claim 5 or 6, wherein the Ni content in the substrate is 0.1 to 0.5 in terms of Ni / (Ni + Co).   The coated cermet according to any one of claims 5 to 7, wherein a content ratio of N in the surface region is larger than that in the sintered body.   The said coating layer consists of a columnar crystal coating layer which consists of a columnar crystal extended in the orthogonal | vertical direction with respect to the surface of the said base | substrate, and whose average crystal width of this columnar crystal is 0.1-1 micrometer. The coated cermet as described.   The coated cermet according to claim 9, wherein the columnar crystal is TiCN.   The coated cermet according to claim 10, wherein the coating layer has a strongest peak at (422) plane in X-ray diffraction measurement.   A cutting tool comprising the Ti-based cermet according to any one of claims 1 to 3 or the coated cermet according to any one of claims 5 to 11, wherein a cutting edge is formed at an intersecting ridge line portion between a rake face and a flank face. The residual stress of the second hard phase applied in the σ ₁₁ direction (direction connecting the center of the rake face and the center of the cutting edge closest to the measurement point) measured by the 2D method on the rake face is 150 MPa or more in terms of compressive stress ( The cutting tool according to claim 12, wherein σ ₁₁ ≦ −150 MPa.