JP2009228085A - Cermet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cermet having high chipping resistance and thermal impact resistance. <P>SOLUTION: The cermet comprising Co and Ni and further comprising one or more selected from the carbide, nitride, and carbonitride of one or more among the group 4, 5 and 6 metals in the periodic table, wherein any of the carbide, nitride and carbonitride is mainly included, and in which the containing ratio between the Co and Ni, (Co content(mass%)/Ni content(mass%)) is 1.1 to 4.0, further, the peak caused by the Co and the peak caused by the Ni are dividedly present in a diffraction pattern by the X-ray diffraction measurement of the pulverized powder, and also, the ratio of the peak intensity I<SB>Co</SB>in the (220) face of the Co to the peak intensity I<SB>Ni</SB>in the (220) face of the Ni, I<SB>Co</SB>/I<SB>Ni</SB>is >0 to 0.5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a cermet suitable as a cutting tool, a wear-resistant member, or a sliding member.

  Currently, WC-based cemented carbides and Ti-based cermets (Ti-based cermets) that require wear resistance, slidability, and fracture resistance, such as cutting tools, wear-resistant members, and sliding members. ) And other sintered alloys are widely used. For these sintered alloys, the development of new compositions has been continued to improve the performance of these sintered alloys. Attempts have also been made to improve the properties of cermets, and improvements to the properties of cermets focusing on the diffraction patterns of X-ray diffraction measurements are also being considered. .

For example, in Patent Document 1, the ratio of the peak intensity Im of the hard dispersed phase / the peak intensity Ic of the iron group metal is 1.1 to 3.0 by X-ray diffraction on the surface of the cermet, and a halo is formed on the low angle side. A cermet cutting tool with a pattern present is disclosed. Patent Document 2 discloses a cermet tool in which the ratio of the peak phase strength of the binder phase (I binder phase) / the peak strength of the hard phase (I hard phase) is 0.01 to 0.7 on the surface with respect to the inside. It is disclosed.
Japanese Patent Application Laid-Open No. 07-96407 JP-A-11-71627

  However, there is a limit in improving the hardness and toughness of the cermet only by changing the ratio of the peak intensity of the hard phase and the binder phase (iron group metal) on the surface as in Patent Documents 1 and 2 above.

  Therefore, the cutting tool of the present invention is for solving the above-mentioned problems, and its purpose is to increase the fracture resistance of the cermet.

The cermet of the present invention contains Co and Ni, and is mainly composed of any of carbides, nitrides, and carbonitrides of Ti, and one or more kinds of carbides of Group 4, 5, and 6 metals of the periodic table, A cermet containing at least one of nitride and carbonitride, wherein the content ratio of Co and Ni (Co content (mass%) / Ni content (mass%)) is 1.1 to 4. In addition, the peak caused by Co and the peak caused by Ni exist separately in the diffraction pattern by X-ray diffraction measurement of the pulverized powder, and the peak intensities I _Co and Ni of the (220) plane of Co exist. The ratio I _Co / I _Ni to the peak intensity I _Ni of the (220) plane is greater than 0 and 0.5 or less.

  Here, in the above configuration, the composition of the cermet is as follows: Co is 5 to 15% by mass, Ni is 2 to 10% by mass, TiCN is 40% by mass or more, VC is 1 to 3% by mass, Periodic Tables 4 and 5 It is desirable to contain 1 to 40% by mass of one or more carbides other than Ti and V among the group 6 metals. Among them, the content ratio of VC (VC / binding phase) with respect to the total mass% of Co and Ni is preferably 0.1 to 0.2.

The cermet of the present invention contains Co and Ni at a ratio of Co content / Ni content of 1.1 to 4.0 in terms of mass%, whereas in the diffraction pattern by X-ray diffraction measurement, The ratio of the peak intensity I _Co of the (220) plane to the peak intensity I Ni of the (220) plane of _Ni , where I _Co / I _Ni is greater than 0 and 0.5 or less, and only I _Co is lower than the conventional cermet. The reason for this is not clear, but the fracture resistance and thermal shock resistance of the cermet are improved.

Here, in the above configuration, the composition of the cermet is as follows: Co is 5 to 15% by mass, Ni is 2 to 10% by mass, TiCN is 40% by mass or more, VC is 1 to 3% by mass, Periodic Tables 4 and 5 In addition, it is desirable to contain 1 to 40% by mass of one or more carbides other than Ti and V among the Group 6 metals from the viewpoint of achieving both wear resistance and fracture resistance of the cermet. Above all, when the content ratio of VC mass% (VC / binding phase) with respect to the total mass% of Co and Ni is 0.1 to 0.2, the above I _Co value can be easily controlled.

  The cermet of the present invention (hereinafter simply abbreviated as cermet) contains Co and Ni and is mainly composed of any one of Ti carbide, nitride, and carbonitride, and is a metal of Group 4, 5, and 6 of the periodic table. 1 or more types of carbides, nitrides, and carbonitrides.

In the cermet of the present invention, the content ratio of Co to Ni (Co content (mass%) / Ni content (mass%): hereinafter simply abbreviated as Co / Ni) is 1.1 to 4.0. In addition, in the diffraction pattern obtained by X-ray diffraction measurement of the powder obtained by pulverizing this cermet shown in FIGS. 1 to 3, the peak caused by Co and the peak caused by Ni exist separately, and Co (220) it is a significant feature ratio _I Co _{/ I Ni} of the peak intensity _{I Ni} of (220) plane peak intensity _{I Co} and Ni in the surface is 0.5 or less greater than 0. With this configuration, the fracture resistance and thermal shock resistance of the cermet are improved.

  Here, when Co / Ni is smaller than 1.1, the thermal shock resistance of the cermet is lowered. Moreover, when Co / Ni exceeds 4.0, the sinterability of a cermet will be impaired and a burnt surface will become rough. A desirable range of Co / Ni is 2.0 to 4.0.

Further, when I _Co / I _Ni is 0, that is, I _Co is not detected, and particularly only a solid solution peak of Co and Ni is detected, the fracture resistance of the cermet is lowered. On the other hand, if I _Co / I _Ni is larger than 0.5, the fracture resistance of the cermet decreases. A desirable range of I _Co / I _Ni is 0.2 to 0.4.

  In the comparison of the peak intensities, the (220) plane is used. However, when the (111) planes are compared with each other, the peak intensity is also reduced due to Co. The reason for using the (220) plane is that when the (111) plane is used, the interval between peaks is narrow and the peaks overlap, so that it is necessary to calculate by peak separation. When the (220) plane is used, peak separation is required. This is because it is possible to easily estimate the peak intensity without reducing the estimation error. Although the reason is unknown, the peak intensity of Ni is also reduced in the (200) plane due to Co and Ni.

Here, in the above composition, the ratio of VC content to the total content of Co and Ni (VC content (mass%) / total content of Co and Ni (mass%)) is 0.1 to 0.2. In some cases, the I _Co value can be easily controlled.

  The desirable composition of the cermet of the present invention is 5-15 mass% Co, 2-10 mass% Ni, 40 mass% or more TiCN, 1.0-3.0 mass% VC, 4th, 5th periodic table. And a composition containing 1 to 40% by mass of one or more carbides other than Ti and V among the group 6 metals, thereby achieving both wear resistance and fracture resistance of the cermet. it can.

  In addition, the total content of the nitrides or carbonitrides of the periodic table group 4, 5, and 6 metal mainly composed of Ti forming the hard phase contained in the cermet is preferably 70 to 96% by mass, In particular, the content is preferably 85 to 96% by mass in terms of improvement in wear resistance. On the other hand, the content ratio of the binder phase is desirably 4 to 30% by mass, particularly 4 to 15% by mass, and this provides an excellent balance between the hardness and toughness of the cermet.

  The average particle size of the hard phase constituting the cermet is preferably 0.2 to 2.0 μm, particularly preferably 0.4 to 1.0 μm. In addition, the particle size of the hard phase in the present invention is measured in accordance with the measuring method of the average particle size of the cemented carbide specified in CIS-019D-2005. At this time, in the case where the hard phase has a cored structure, the particle diameter is measured with one hard phase extending to the outer edge of the peripheral portion including the core portion and the peripheral portion.

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

First, a TiCN powder having an average particle size of 0.1 to 2 μm, desirably 0.2 to 1.2 μm, a VC powder having an average particle size of 0.1 to 2 μm, and the above-described other having an average particle size of 0.1 to 2 μm Any one of metal carbide powder, nitride powder or carbonitride powder, Co powder having an average particle size of 0.8 to 2.0 μm, Ni powder having an average particle size of 0.5 to 2.0 μm, If necessary, a mixed powder prepared by mixing MnCO ₃ powder having an average particle size of 0.5 to 10 μm is prepared. In addition, although TiC powder and TiN powder may be added in the raw material, these raw material powders constitute TiCN in the cermet after firing.

  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) a step of raising the temperature from room temperature to 1200 ° C. in vacuum, (b) 0.1 to a firing temperature (referred to as temperature T ₁ ) of 1200 to 1330 to 1380 ° C. in vacuum. a step of raising the temperature at to 2 ° C. / minute heating rate _{r 1,} 1,450 to 1,600 ° C. from temperature _{T 1} of switching the atmosphere in the firing furnace in an inert gas atmosphere 30~2000Pa at (c) temperatures _{T 1} A step of raising the temperature at a heating rate r ₂ of 4 to 15 ° C./min to a firing temperature (referred to as temperature T ₂ ), and (d) 0. 0 at the temperature T ₂ in an inert gas atmosphere of 30 to 2000 Pa. step of holding 5 to 2 hours, (e) a step of further held for 30 to 60 minutes by changing the vacuum atmosphere while the furnace was maintained at this sintering temperature, (f) cooling rate 5 from temperature _{T 2} to 1100 ° C. A step of vacuum cooling at 15 ° C./min, (g) 1100 ° C. The lowered when the inert gas to the step of rapid cooling by introducing a gas pressure of 0.1MPa~0.9MPa of (a) ~ (g) a step of firing in a firing pattern performed sequentially.

That is, among the above firing conditions, voids are generated on the surface of the cermet when the heating rate r ₁ in the step (b) is made higher than 2 ° C./min. If the heating rate r ₁ is slower than 0.1 ° C./min, the firing time becomes too long, and the productivity is greatly reduced. (C) the surface voids are generated when the following low-pressure gas atmosphere vacuum or 30Pa Atsushi Nobori from temperature T ₁ of the process. (D) In the case where all the holdings at the firing temperature of the temperature T _{2 in} the step (e) are vacuum or a low pressure gas atmosphere of 30 Pa or less, all the holdings at the firing temperature of the temperature T ₂ are inert gases with a gas pressure of 30 Pa or more. When the atmosphere is used, when the cooling steps (f) and (g) are all vacuum or a low-pressure gas atmosphere of 30 Pa or less, it is difficult to control the I _Co / I _Ni ratio to a desired ratio. (F) When the cooling rate of the process is higher than 15 ° C./min, it appears as one peak without being separated into a peak caused by Co and a peak caused by Ni, and (f) the cooling rate of the process is 5 ° C. If it is slower than / min, it is difficult to control I _Co / I _Ni to a predetermined ratio.

  Then, if desired, a coating layer is formed on the surface of the cermet 1. A physical vapor deposition (PVD) method such as an ion plating method or a sputtering method can be applied as a method for forming the coating layer. In addition, since there is almost no precipitation of Ni in the surface region of the cermet 1, the crystals constituting the coating layer such as TiCN crystals do not grow abnormally even by chemical vapor deposition (CVD) method, and have high hardness with fine crystals, A coating layer having excellent welding resistance can be formed.

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, and VC having an average particle diameter of 1.0 μm as measured by the microtrack method. Powder, TaC powder with an average particle size of 2 μm, 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, 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 a pressure of 200 MPa, and (a) chamber in vacuum Up to 1200 ° C. the temperature was raised at 10 ° C. / minute from, (b) 1300 ℃ from 1200 ° C. (sintering temperature _{T 1)} was heated at a heating rate _r 1 = 0.8 ℃ / min up, (c) 1350 ° C. (temperature _{T 1)} until sintering temperature _{T 2} shown in Table 2 was heated at a heating rate _r 2 = 8 ° C. / min in a vacuum from, shown in Table 2 at (d) sintering temperature _{T 2} After maintaining the firing atmosphere and firing time t ₁ , (e) holding only the firing atmosphere and firing time t ₂ shown in Table 2 at the firing temperature T ₂ , and (f) Table 2 from temperature T ₂ to 1100 ° C. Cool at the atmosphere and cooling rate, and (g) cool at 1100 ° C. and thereafter in the atmosphere shown in Table 2. 1 to 15 cermet throwaway chips were obtained.

The obtained cermet was subjected to ICP analysis using the powder obtained by pulverizing the cermet, the content ratio of each component of the cermet was determined, and the ratio of Co and Ni was calculated. Further, X-ray diffraction measurement was performed using a cermet ground powder in a diffraction angle range of 2θ = 30 to 80 °, and peak intensity I _Co and Ni (220) planes originated from the Co (220) plane from the diffraction chart. I _Co / I _Ni was calculated by comparing the peak intensities I _Ni .

  Furthermore, observation with a scanning electron microscope (SEM) was performed, and image analysis was performed in a region of 8 μm × 8 μm using a commercially available image analysis software at an arbitrary 5 locations on the surface and inside of the photo at a magnification of 10,000 times. The average particle size of was calculated. 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.
Cutting test 1 (Evaluation of fracture resistance)
Work material: S45C
Cutting speed: 120 m / min
Feed: 0.05-0.05mm / rev
Cutting depth: 1.5mm
Cutting state: Dry evaluation method: Time until chipping at each feed 10S Cutting test 2 (Abrasion resistance evaluation)
Work material: SCM435
Cutting speed: 250 m / min
Feed: 0.25mm / rev
Cutting depth: 1.5mm
Cutting condition: wet (use water-soluble cutting fluid)
Evaluation method: Time until the wear amount reaches 0.2 mm

From Tables 1-3, sample No. which does not contain Ni. In No. 11, the sintering was insufficient, and both wear and chipping were bad. Sample No. with Co / Ni exceeding 5 10 and sample no. In 7 to 9, I _Co / I _Ni was larger than 0.5 in all cases, and the fracture resistance decreased. Furthermore, the sample No. 1 whose cooling rate in the step (f) is faster than 15 ° C./min. No. 12 appears as one peak without being separated into a peak caused by Co and a peak caused by Ni, and other firing conditions do not match Sample No. Even in 13 to 15, I _Co / I _Ni was larger than 0.5, and all of them had poor fracture resistance.

  On the other hand, sample no. In Nos. 1 to 6, all exhibited excellent wear resistance and good wear resistance. As a result, the tool life was long.

The respective diffraction charts when X-ray diffraction measurement is performed on powders obtained by pulverizing the cermet (b) of the present invention and the conventional cermets (a) and (c) are shown. The enlarged view about diffraction angle (2 (theta)) = 43-45 degrees is shown about the diffraction chart of FIG. The enlarged view about diffraction angle (2 (theta)) = 70-80 degrees is shown about the diffraction chart of FIG.

Explanation of symbols

Peak intensity due to I _Co : Co (220) plane I _Ni : Peak intensity due to Ni (220) plane

Claims (3)

Co and Ni are contained, and mainly Ti carbide, nitride, carbonitride, and one or more carbides, nitrides, and carbonitrides of Periodic Tables 4, 5, and 6 metals A cermet containing at least one of the following, wherein the content ratio of Co and Ni (Co content (mass%) / Ni content (mass%)) is 1.1 to 4.0, and pulverization In the diffraction pattern of the powder obtained by X-ray diffraction measurement, the peak due to Co and the peak due to Ni exist separately, and the peak intensity of _Co (220) plane I _Co and the peak of Ni (220) plane A cermet characterized in that the ratio I _Co / I _Ni to strength I _Ni is greater than 0 and 0.5 or less.   Co is 5 to 15% by mass, Ni is 2 to 10% by mass, TiCN is 40% by mass or more, VC is 1 to 3% by mass, 1 of the periodic table 4, 5, and 6 metals other than Ti and V The cermet according to claim 1, wherein the cermet contains at least one kind of carbide in a proportion of 1 to 40% by mass.   The ratio of VC content to the total content of Co and Ni (VC content (mass%) / total content of Co and Ni (mass%)) is 0.1 to 0.2. The cermet according to Item 2.

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