JP5127110B2 - TiCN-based cermet and method for producing the same - Google Patents

Description

  The present invention relates to a TiCN-based cermet having both toughness and hardness suitable for cutting tool members, wear-resistant tool members, and the like, and a method for producing the same.

  Conventionally, TiC-based cermets and TiCN-based cermets have been developed as wear-resistant tools and cutting tool alloys, and TiCN-based cermets with improved toughness have been widely used.

Such TiCN-based cermets are particularly required to have improved fracture resistance. For example, in Patent Document 1, the hard phase is in a solid solution state, specifically, a hard core having a cored structure with a black core. It is disclosed that by optimizing the existence ratio of the phase and the hard phase having a core structure with a white core, and the particle size thereof, it is possible to improve the excellent durability against thermal shock generated by high-speed cutting, etc. ing.
JP-A-8-199283

  However, even with the cermet disclosed in Patent Document 1, the durability against thermal shock is still insufficient, and there is a limit to the improvement of cutting performance, and further improvement of thermal shock resistance and improvement of fracture resistance and wear resistance. Was demanded.

  The present invention is for solving the above-mentioned problems, and its purpose is to further improve the fracture resistance by optimizing the structure by optimizing the solid solution state of the hard phase of the TiCN-based cermet for each place and The purpose is to improve chipping resistance and wear resistance.

  In the present invention, by optimizing the particle size of the raw material powder and the firing conditions, the solid solution state of the hard phase is optimized according to each part, and the strength and hardness improvement by atomizing the hard phase inside the cermet, As a result of satisfying both the hardness maintenance and the thermal shock resistance improvement on the cermet surface, it was found that both the fracture resistance and the wear resistance of the cermet as a whole improved.

That is, the TiCN-based cermet of the present invention is at least one of carbides, nitrides, and carbonitrides of at least one metal selected from TiCN and metals of Group IVa, Va and VIa other than Ti. In a scanning electron micrograph (SEM) of a TiCN group cermet formed by bonding a hard phase containing Co and / or Ni at a binder phase of 1 to 30% by weight, wherein the TiCN group cermet has an arbitrary cross section. The hard phase is selected from the first hard phase containing 80% by weight or more of Ti as the metal component, and 30 to 70% by weight of Ti as the metal component, and metals of the periodic table IVa, Va and VIa other than Ti A second hard phase comprising a total amount of at least one metal of 70 to 30% by weight and a total amount of Co and / or Ni binder phase metals of 0 to 3% by weight,
When a range from the surface of the cermet to a depth of 20 μm is a surface region, and the inside of the surface region is an internal region,
The average particle size d _1in of the first hard phase inside the cermet is 0.05 to _1.5 μm, and the area ratio S _1in of the first hard phase occupying the whole inside of the cermet is 40 to 80% by area,
The ratio between the average particle diameter _{d 1in} the first hard phase in the cermet inner and an average particle diameter _{d 1SF} of the first hard phase in the surface region _(d 1sf _/ d _1in) is 1.1 to 3, the cermet characterized in that the ratio between the area ratio _{S 1in} of the first hard phase in the cermet inner and area ratio _{S 1SF} of the first hard phase occupying the surface area _(S 1sf _/ S _1in) consists of from 0.3 to 0.7 It is what.

Here, the first hard phase contains 80% by weight or more of Ti as a metal component,
The second hard phase is 30 to 70% by weight of Ti as a metal component, periodic table IVa, Va other than Ti
And the total amount of at least one metal selected from the group VIa metals is 70 to 30% by weight, and the total amount of Co and / or Ni binder phase metals is 0 to 3% by weight, This is important in that toughness can be maintained while increasing the hardness of the cermet.

Moreover, the further electrode surface located in a surface portion of the surface area in the cermet area ratio S _1ss of the first hard phase can be 80 area% or more of the pole surface area ss is additionally present, cermet wear It is desirable in that it can maintain the sex.

Furthermore, the method for producing a TiCN-based cermet according to the present invention includes at least one selected from TiCN powder having an average particle size of 0.1 to 1.2 μm and metals of Group IVa, Va and VIa other than Ti. After a seed metal carbide, nitride and carbonitride powder and Co and / or Ni were mixed and processed into a predetermined shape, (A) 1150 at a temperature rising rate of 0.7 to 2 ° C./min. The temperature is increased to ˜1250 ° C., then (B) the temperature is increased to 1400 to 1500 ° C. at a temperature increase rate of 5 to 15 ° C./min, and (C) is further increased to 1500 to 1600 at a temperature increase rate of 4 to 14 ° C./min. The temperature is raised to 0 ° C., and in the temperature raising step (B) (C), the firing furnace is filled with nitrogen gas or an inert gas so as to have an atmosphere of 10 to 150 Pa. Maintain the temperature for a specified time and lower the temperature. It is characterized by this.

  According to the TiCN-based cermet of the present invention, the solid solution state of the hard phase is optimized according to each part, the strength and hardness are improved by atomizing the hard phase inside the cermet, the hardness is maintained on the cermet surface, and the thermal shock is applied. As a result of being able to satisfy both the improvement in property, both the fracture resistance and the wear resistance of the cermet as a whole are improved.

  In addition, according to the TiCN-based cermet manufacturing method of the present invention, the solid phase of the hard phase is optimized according to each part by optimizing the particle size of the raw material powder and the firing conditions, and the hard phase inside the cermet is optimized. As a result of satisfying both strength and hardness improvement by atomization, maintenance of hardness on the cermet surface and improvement of thermal shock resistance, both the fracture resistance and wear resistance of the cermet as a whole are improved.

  FIG. 1A is a scanning electron micrograph (SEM) of an arbitrary cross section including the surface of the TiCN-based cermet of the present invention (hereinafter simply abbreviated as cermet) and an SEM photograph of an internal arbitrary cross section. This will be described with reference to FIG.

Referring to FIG. 1, the TiCN-based cermet (hereinafter simply referred to as cermet) 1 of the present invention is at least one selected from metals of Group IVa, Va and VIa other than TiCN and Ti. The hard phase 2 formed by dissolving at least one of metal carbide, nitride, and carbonitride is a structure in which the hard phase 2 is bonded with a binder phase 3 of 1 to 30% by weight of Co and / or Ni. According to FIG. 1, the hard phase 2 is black and contains the first hard phase 2a containing 80 wt% or more of Ti as a metal component, and the white hard metal 2 is 30 to 70 wt% of Ti as a metal component, and a periodic table other than Ti. The total amount of at least one metal selected from the group IVa, Va and VIa metals is
70 to 30% by weight, and the second hard phase 2b having a total amount of Co and / or Ni binder phase metals of 0 to 3% by weight. According to the present invention, the inside of the cermet 1 (FIG. 1 ( There is a surface region sf (FIG. 1 (a)) made of a tissue different from b)).

According to the present invention, the average particle diameter d _1in of the first hard phase 2a in the cermet 1 (FIG. 1 (b): in) is 0.05 to _1.5 μm, and the first hard phase 2a is in the cermet 1. The area ratio S _1in occupies 40 to 80 area%, the average particle diameter d _1sf of the first hard phase 2a on the surface of the cermet 1 (FIG. 1 (a)), and the first hard phase 2a inside the cermet 1 the ratio between the average particle diameter _{d 1in (d 1sf / d 1in} ) is 1.1 to 3, the area of the first hard phase in area ratio _{S 1SF} and cermet inside the first hard phase occupying the cermet 1 surface portion ratio S ratio of _{1in (S 1sf /} S _1in) surface region consisting of 0.3 to 0.7 (Fig. 1 (a): sf) is a significant feature is present.

  As a result, the strength of the cermet 1 can be increased, and while maintaining the hardness of the cermet 1 surface, the thermal conductivity and Young's modulus can be increased to improve the thermal shock resistance on the surface of the cermet 1, thereby enabling particularly high-speed cutting. The wear resistance and fracture resistance of the cermet 1 can be improved even under conditions that cause severe thermal shock such as high feed cutting and wet cutting.

Incidentally, the average particle size _(d 1, _{d 2)} and the area ratio _(S 1, _{S 2),} for scanning electron microscope (SEM) photograph can be measured by using a commercially available image analyzer.

Here, when the average particle diameter d _1in of the first hard phase 2a inside the cermet ₁ is smaller than 0.05 μm, the structure becomes inhomogeneous due to aggregation of the hard phases, leading to a decrease in strength, and heat conduction inside the cermet 1. The rate drops. On the other hand, when d _1in exceeds 0.5 μm, the strength and hardness of the cermet 1 are lowered, and both the fracture resistance and the wear resistance are lowered. desired range of d _1in is 0.1 to 0.3 [mu] m.

Further, when the area ratio S _1in of the first hard phase 2a is less than 40 area% or more than 80 area%, the strength and hardness of the cermet 1 are lowered. A desirable range of S _1in is 50 to 70 area%.

Further, the average particle diameter d2in of the second hard phase 2b in the cermet 1 is desirably 0.6 μm to ₂ μm from the viewpoint of improving the strength by making the dispersed state of the second hard phase 2b good. A more desirable range of d _2in is 0.8 to 1.5 μm.

Further, the area ratio _S2in of the second hard phase 2b in the cermet 1 is 5 to 40 area%, so that the particles of the cermet 1 can be sufficiently sintered with fine particles, and the strength is improved. desirable. A more desirable range of the area ratio _S2in is 10 to 30 area%.

On the other hand, in the cermet 1 surface region, the ratio of the average particle diameter _{d 1in} the first hard phase 2a in the average particle diameter _{d 1SF} and the cermet 1 inside the first hard phase 2a in the cermet 1 surface _(d 1sf _/ d _1in) resistant but less thermal conductivity and plastic deformation resistance is lowered than 1.1, conversely, the hardness in the ratio _(d 1sf _/ d _1in) is large, the cermet 1 surface than 3 drops Abrasion is reduced. The average particle diameter d _2sf of the second hard phase 2b in the cermet 1 surface region is 1 μm to 3 _μm in terms of maintaining the thermal conductivity and plastic deformation resistance of the cermet 1 surface and increasing the fracture resistance. desirable. A desirable range of d _2sf is 1.2 to 2 μm.

Further, the area ratio S _1sf of the first hard phase 2a in the cermet 1 surface region sf is _preferably 5 to 40 area% from the viewpoint of improving the thermal conductivity and plastic deformability of the cermet 1 surface. A desirable range of S _1sf is 7 to 25 area%.

The ratio between the area ratio _{S 1in} of the first hard phase in the cermet inner and area ratio _{S 1SF} of the first hard phase occupying the cermet 1 surface area sf _(S 1sf _/ S _1in) is as shown in FIG. 2 0. If it is less than 3, the thermal conductivity and plastic deformation resistance of the cermet 1 will be reduced. Conversely, if it exceeds 0.7, the fracture resistance of the surface of the cermet 1 will be reduced due to insufficient first hard phase and binder phase. The ratio of the area ratio _{(S 1sf /} S _1in) is 1.1 to 2, and is preferably 1.2 to 1.8.

The area ratio _S2sf of the second hard phase 2b is preferably 50 to 80 area%, particularly 60 to 75 area%, from the _viewpoint of _fracture resistance and wear resistance of the cermet 1 surface.

  Furthermore, according to the present invention, the white portion 2c is present at the center of the grayish white second hard phase 2b, and the proportion of the white portion 2c in the cermet 1 (FIG. 1B) is the surface of the cermet 1 (see FIG. 1 (a)) is larger than the abundance of the white portion 2c, the hard phase 2 (2a, 2b) inside the cermet 1 is atomized to increase the strength of the cermet 1 and the hard phase 2 (2a on the surface of the cermet 1). 2b) is preferable in terms of improving the thermal shock resistance of the cermet 1 by optimizing the solid solution state.

Further, it is important for the first hard phase 2a to contain 80% by weight or more of Ti as a metal component. In particular, Ti is 80 to 98% by weight, and periodic tables IVa, Va and VIa other than Ti are used.
The total amount of at least one metal selected from group metals, particularly one or more of W, Mo, Cr, Nb and V, and further containing W as an essential component (referred to as a solid solution metal in the present invention). It is desirable that the total amount of the binder phase metal of Co and / or Ni is 1 to 15% by weight and 0 to 3% by weight.

Further, the grayish white second hard phase 2b is important to contain a large amount of solid solution metal with respect to the first hard phase 2a , and in particular, Ti is 30 to 70% by weight, and the total amount of solid solution metal is 70 to 70%. It is important that 30% by weight and the total amount of Co and / or Ni binder phase metal is comprised between 0 and 3% by weight. The content ratio of the metal component in the hard phase can be measured by energy dispersive spectroscopy (EDS) of a transmission electron microscope (TEM).

  Further, according to the present invention, the hard phase 2 has a double-core structure in which the first hard phase 2a is a core part and the second hard phase 2b is a peripheral part. The cermet 1 has a fine and uniform structure and is excellent in wettability with the binder phase 3 so that it contributes to increasing the strength of the cermet 1, but all the hard phases 2 have a cored structure. It does not have to be. In the case of the cored structure, the area of the second hard phase 2b is the area of the annular portion excluding the area of the first hard phase 2a at the center.

Further, according to the present invention, the strength of the cermet 1, the hardness, in order to optimize the balance between thermal shock _{resistance, d 2sf / d 2in = 1.5~1.7} , S 2sf / S 2in = 1.5 It is desirable to be ~ 4.

Further, in order to achieve both _fracture resistance and wear resistance of the cermet 1, the thickness from the surface of the cermet in the region composed of the same structure as d _1sf , d _2sf , S _1sf , and S _2sf of the surface region is 20 to 100 μm. In particular, it is desirable to set it as 30-50 micrometers. Moreover, it is possible to maintain the wear resistance of the cermet 1 that the pole surface region ss having an area ratio S1s of the first hard phase 2a of 80 area% or more is present on the pole surface located further on the surface portion of the surface region. Desirable in terms.

  In addition, it is desirable that the Vickers hardness in the cermet 1 takes a maximum value in the extreme surface region, and the Vickers hardness gradually decreases toward the inside. Thereby, it can have both high abrasion resistance and defect resistance.

  Moreover, according to the present invention, a hard coating layer may be separately formed on the surface of the cermet 1.

(Production method)
Next, the manufacturing method of the TiCN base cermet of this invention is demonstrated.

  First, TiCN powder having an average particle size of 0.1 to 1.2 μm, particularly 0.2 to 0.9 μm, TiN powder having an average particle size of 0.1 to 2 μm, the above-described solid solution metal carbide powder, nitride powder or A mixed powder obtained by mixing any one of the carbonitride powders with Co powder and / or Ni powder is prepared.

  According to the present invention, it is important to control the average particle size of the TiCN raw material powder in the range of 0.1 to 1.2 μm. If the average particle size is smaller than 0.1 μm, the raw material aggregates and the cermet Becomes a heterogeneous structure, and conversely, if it exceeds 1.2 μm, the cermet cannot be made the above-described structure. Since the TiCN raw material powder forms a cored structure of the first hard phase and the second hard phase by sintering together with other solid solution metal raw materials, the average particle size of the first hard phase 2a is the same as that of the TiCN raw material powder. It tends to be smaller than the average particle size.

  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, the molded body is made of a carbide of at least one metal selected from TiCN powder having an average particle diameter of 0.1 to 1.2 μm and a metal of Group IVa, Va and VIa other than Ti. ,
Nitride and carbonitride powder and Co and / or Ni are prepared and processed into a predetermined shape, and then (a) the temperature is increased to 1150 to 1250 ° C. at a temperature increase rate of 0.7 to 2 ° C./min. Then, (b) the temperature is raised to 1400-1500 ° C. at a rate of 5-15 ° C./min, and (c) the temperature is raised to 1500-1600 ° C. at a rate of 4-14 ° C./min. In the temperature raising step (b) (c), nitrogen gas or an inert gas is filled to become an atmosphere of 10 to 150 Pa, maintained at the maximum temperature of the temperature raising step (c) for a predetermined time, and lowered in temperature. .

  According to the present invention, the cermet having the above-described structure can be produced by lowering the temperature in a state where the temperature rise rate during the firing and a predetermined amount of inert gas is filled when the temperature is lowered.

The average particle diameter of 0.7μm in the measurement by micro track method or 2 [mu] m TiCN powder,, TiN powder having an average particle diameter of 1.5 [mu] m, TaC powder having an average particle diameter of 2 [mu] m, NbC powder having an average particle diameter of 1.5 [mu] m, average A WC powder having a particle diameter of 1.1 μm, a ZrC powder having an average particle diameter of 1.8 μm, a VC powder having an average particle diameter of 1.0 μm, a Ni powder having an average particle diameter of 2.4 μm, and a Co powder having an average particle diameter of 1.9 μm. The mixed powder adjusted in the ratio shown in Table 1 is wet-mixed with isopropyl alcohol (IPA) using a stainless steel ball mill and cemented carbide balls, 3% by weight of paraffin is added and mixed, and then press molded into CNMG120408 at 200 MPa. Then, firing was performed under the firing conditions shown in Table 1. In the temperature raising steps (b) and (c), N ₂ gas was injected in an amount shown in Table 1.

The obtained cermet was processed with a diamond grindstone, and the cutting performance was evaluated under the following conditions. In addition, each sample was observed with a scanning electron microscope (SEM), and image analysis was performed in an area of 7 μm × 7 μm using a commercially available image analysis software for arbitrary five places of 7000 × photographs to obtain a hard phase (first The existence state of the hard phase and the second hard phase) was confirmed.
The results are shown in Table 2.

(Cutting conditions)
Cutting evaluation 1
Cutting method: Turning Continuous cutting (Abrasion resistance evaluation)
Cutting speed: 230 m / min
Feeding: 0.25mm / rev
Cutting depth: 2.0mm
Work material: SCM435
Cutting state: wet (emulsion)
Cutting time: 10 minutes Evaluation item: Flank wear width (mm)
Cutting evaluation 2
Cutting method: Turning Interrupted cutting (Evaluation of fracture resistance)
Work material: S45C
Work material: Round bar with 4 grooves,
Cutting speed: 100 m / min,
Feeding and cutting time: After cutting for 10 seconds at 0.1 mm / rev, feed is increased by 0.05 mm / rev and cut for 10 seconds each (up to a maximum feed of 0.5 mm / rev)
Cutting depth: 2mm
Evaluation item: Total cutting time until chipping Cutting state: Wet (emulsion)

From Tables 1 and 2, Sample No. In 1-4, the result which was excellent in both abrasion resistance and defect resistance was shown. On the other hand, sample No. fired with a simple firing pattern. In No. 5, a predetermined surface area was not formed on the surface, and both wear resistance and fracture resistance were reduced. Sample No. using TiCN powder having an average particle diameter of 2 μm as a raw material. In _No. 6, the average particle diameter d _1in of the hard particles inside the sintered body exceeded 1.5 μm, and the hardness and strength decreased. As a result, tool wear progressed early. Furthermore, in the temperature rising step B, the heating rate is lower than 4 ° C., and the sample No. In 7 the ratio of the average particle diameter _{d 1in} the first hard phase _{(d 1sf /} d _1in) was intended reduced wear severe than 1.1. Furthermore, sample No. No. in which the heating rate A was slower than 0.7 ° C./min and no inert gas was introduced in the heating steps b and c. In 8 ratio between the average particle diameter _{d 1in} the first hard phase _{(d 1sf /} d _1in) has drops significantly wear resistance than 3.

It is a scanning electron micrograph about (a) surface and (b) inside of TiCN base cermet of the present invention. It is a scanning electron micrograph about (a) surface and (b) inside of the conventional TiCN base cermet.

Explanation of symbols

1: TiCN-based cermet 2: hard phase 2a: first hard phase 2b: second hard phase 3: bonded phase in: inside of cermet sf: cermet surface area ss: cermet pole surface area

Claims (3)

A hard phase comprising TiCN and at least one carbide, nitride and carbonitride of at least one metal selected from metals of Group IVa, Va and VIa of the periodic table other than Ti, Co and / or TiCN-based cermet bonded with 1 to 30% by weight of Ni-bonded phase, wherein in the scanning electron micrograph (SEM) of the TiCN-based cermet arbitrary cross section, the hard phase has Ti as a metal component. A total amount of at least one metal selected from the group consisting of metals of the first hard phase containing at least wt%, 30 to 70 wt% of Ti as a metal component, and periodic table IVa, Va and VIa other than Ti A second hard phase comprising 70 to 30% by weight and a total amount of Co and / or Ni binder phase metals of 0 to 3% by weight;
When a range from the surface of the cermet to a depth of 20 μm is a surface region, and the inside of the surface region is an internal region,
The average particle size d _1in of the first hard phase inside the cermet is 0.05 to _1.5 μm, and the area ratio S _1in of the first hard phase occupying the whole inside of the cermet is 40 to 80% by area,
The ratio between the average particle diameter _{d 1in} the first hard phase in the cermet inner and an average particle diameter _{d 1SF} of the first hard phase in the surface region _(d 1sf _/ d _1in) is 1.1 to 3, the cermet characterized in that the ratio between the area ratio _{S 1in} of the first hard phase in the cermet inner and area ratio _{S 1SF} of the first hard phase occupying the surface area _(S 1sf _/ S _1in) consists of from 0.3 to 0.7 TiCN-based cermet. A hard phase comprising TiCN and at least one carbide, nitride and carbonitride of at least one metal selected from metals of Group IVa, Va and VIa of the periodic table other than Ti, Co and / or A TiCN-based cermet bonded with 1 to 30% by weight of a Ni-bonded phase, wherein the hard phase is 80 wt% of Ti as a metal component in a scanning electron micrograph (SEM) of an arbitrary cross-section of the TiCN-based cermet. 30% to 70% by weight of Ti as the first hard phase and the metal component, and the total amount of at least one metal selected from Group IVa, Va and VIa metals other than Ti is 70 to 70%. 30% by weight, comprising a second hard phase comprising a total amount of Co and / or Ni binder phase metals of 0 to 3% by weight,
An area ratio S 1 _ss of the first hard phase is 80 area% or more and a depth of 5 μm or less exists on the surface of the cermet, and a range from the pole surface area to a depth of 20 μm is a surface area, When the inside of the surface area is the internal area,
The average particle size d _1in of the first hard phase inside the cermet is 0.05 to _1.5 μm, and the area ratio S _1in of the first hard phase occupying the whole inside of the cermet is 40 to 80% by area,
The ratio between the average particle diameter _{d 1in} the first hard phase in the cermet inner and an average particle diameter _{d 1SF} of the first hard phase in the surface region _(d 1sf _/ d _1in) is 1.1 to 3, the cermet characterized in that the ratio between the area ratio _{S 1in} of the first hard phase in the cermet inner and area ratio _{S 1SF} of the first hard phase occupying the surface area _(S 1sf _/ S _1in) consists of from 0.3 to 0.7 TiCN-based cermet. Of TiCN powder having an average particle size of 0.1 to 1.2 μm and at least one metal carbide, nitride and carbonitride selected from metals of group IVa, Va and VIa other than Ti After powder and Co and / or Ni were mixed and processed into a predetermined shape, (A) the temperature was raised to 1150 to 1250 ° C. at a temperature rising rate of 0.7 to 2 ° C./min, and (B) 5 The temperature is increased to 1400-1500 ° C. at a temperature increase rate of ˜15 ° C./min, and (C) the temperature is increased to 1500-1600 ° C. at a temperature increase rate of 4-14 ° C./min. ) In (C), the firing furnace is filled with nitrogen gas or an inert gas so as to have an atmosphere of 10 to 150 Pa, maintained at the maximum temperature in the temperature raising step (C) for a predetermined time, and the temperature is lowered. A method for producing a TiCN-based cermet.

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