JP2006328477A - Wc based cemented carbide member, and coated wc based cemented carbide member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a WC based cemented carbide and a hard film-coated WC based cemented carbide member in which wear, chipping or the like caused by melt-stuck or the like are reduced by improving the melt-stuck resistance of a microparticulate cemented carbide member to a work. <P>SOLUTION: In the WC based cemented carbide member, the WC based cemented carbide comprises a bonding phase essentially consisting of Co, a hard phase essentially consisting of WC, and a plural carbide phase 1 (V<SB>x</SB>W<SB>y</SB>Cr<SB>z</SB>Ta<SB>α</SB>Nb<SB>β</SB>)C comprising V, W, Cr, Ta and/or Nb with the average particle diameter of ≤0.8 μm. Here, 1≤S≤50 is satisfied regarding the metallic components of the plural carbide phase, provided that, by weight%, X+Y+Z+α+β=100, 20≤X≤70, 20≤Y≤70, 1≤Z≤30 and α+β=S. The plural carbide phase is present adjacently to the hard phase or adjacently to the bonding phase 3 and the hard phase, and the area ratio M(%) of the plural carbide phase satisfies 0<M<0.5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fine cemented carbide having WC particles having an average particle diameter of 0.8 μm or less, and a hard coating-coated WC-based cemented carbide member obtained by coating a fine cemented carbide with a hard coating.

  Specific examples of the fine-grain cemented carbide having an average WC grain size of 0.8 μm or less are disclosed in Patent Documents 1 to 7 below.

Japanese Patent No. 3451940 Japanese Patent No. 3451949 Japanese Patent No. 3291562 Japanese Patent No. 3451950 JP 2004-162080 A Japanese Patent Laid-Open No. 9-184042 JP-A-2005-054258

Patent Documents 1 and 2 both describe a hard dispersed phase in which WC is entirely coated and / or partially coated with a thin layer of precipitated composite carbides of V, W, and Cr, but other hard dispersed phases are described. There is no description. Patent Documents 3, 4 and 5 all describe the first hard dispersed phase and the second hard dispersed phase, but the second hard dispersed phase is a precipitation composite of V, W and Cr finely dispersed in the binder phase. It is described that it consists of carbides, and there is no description about those components. Patent Document 6 discloses a cemented carbide to which VN is added, but there is a description that 1 part of N is dissolved in Co, but there is no description of precipitates. Patent Document 7 discloses a fine-grain cemented carbide added with Ta and / or Nb. Although there is a description that the hardness and heat resistance of the binder phase are increased, there is no description about the affinity with metals and alloys. Therefore, Patent Documents 1 to 7 do not disclose a technique for improving the welding resistance.
The problem to be solved by the present invention is to reduce wear, chipping and the like due to welding or the like by improving the welding resistance of the fine cemented carbide member to the workpiece. Furthermore, the WC-based cemented carbide and the hard coating-coated WC-based cemented carbide that maintain the high toughness and hardness inherently possessed by the fine-grained cemented carbide member and can extend the service life through a synergistic effect with the improvement of the welding resistance. It is to provide a member. For example, as a member, it is applied to an end mill, a drill, etc., and it is enabling diameter reduction.

The WC-based cemented carbide of the present invention has an average particle diameter of WC of 0.8 μm or less, wt%, Co content of 3 ≦ Co ≦ 13%, and Cr content of 0.3 ≦ Cr ≦ 1.0, V content is 0.2 ≦ V ≦ 0.5, Ta and / or Nb content is 0 <(Ta and / or Nb) ≦ 1.5, balance is from WC and inevitable impurities The WC-based cemented carbide comprises a binder phase mainly composed of Co, a hard phase mainly composed of WC, V, W, and Cr having an average particle size of 0.8 μm or less. And a double carbide phase (V _x W _y Cr _z Ta _α Nb _β ) C containing Ta and / or Nb, provided that the metal component of the double carbide phase is by weight, X + Y + Z + α + β = 100, 20 ≦ X ≦ 70, 20 ≦ Y ≦ 70, 1 ≦ Z ≦ 30, α + β = S, 1 ≦ S ≦ 50. More than WC group, characterized in that the area ratio M (%) of the double carbide phase is adjacent to the phase or adjacent to the binder phase and the hard phase, and 0 <M <0.5 It is a hard alloy member. By adopting this configuration, it is possible to improve the welding resistance of the fine cemented carbide member to the workpiece. As a result, it is possible to reduce wear and chipping due to welding and the like. Furthermore, the WC-based cemented carbide and the hard coating-coated WC-based cemented carbide that maintain the high toughness and hardness inherently possessed by the fine-grained cemented carbide member and can extend the service life through a synergistic effect with the improvement of the welding resistance. A member can be provided. For example, if the member is applied to an end mill, a drill or the like, the diameter can be reduced.

The hardness of the WC-based cemented carbide member of the present invention on the Rockwell A scale (hereinafter referred to as HRA) is preferably 93 or more and 95 or less. The WC-based cemented carbide member includes drills, small-diameter drills, end mills, tip milling inserts for end milling, tip replacements for milling, tip replacements for turning, metal saws, gear cutting tools, gun drills, reamers, broaches And one selected from the group consisting of taps. In particular, a metal processing end mill having a diameter of 2 mm or less, a printed circuit board drill having a diameter of 0.2 mm or less, and a router end mill for a printed circuit board having a diameter of 1.5 mm or less are more preferable.
The WC-based cemented carbide member of the present invention is coated with a hard film, and the hard film has one or more elements selected from periodic table 4a, 5a, 6a group elements, Al, and Si as metal components. It is preferable that the nonmetallic component has one or more elements selected from C, N, O, and B.

  By this invention, the welding resistance with respect to the workpiece of a fine-grain cemented carbide member was able to be improved. As a result, it has become possible to reduce wear and chipping due to welding and the like. Further, the WC-based cemented carbide and the hard coating-coated WC-based cemented carbide that maintain the high toughness and hardness inherently possessed by the fine-grain cemented carbide member and can extend the service life by synergistic effects with the improvement of the welding resistance. A member could be provided. In particular, the diameters of end mills, drills, etc. can be reduced, the tool life has been greatly improved, and an effect has been obtained for industrial use.

The WC-based cemented carbide of the present invention can improve the welding resistance in addition to the inherently high toughness and high hardness. For example, characteristics of members such as tools can be improved. The reason for the numerical limitation of the present invention will be described below.
The reason why the average particle size of WC is 0.8 μm or less is that it is effective for increasing the hardness of the cemented carbide. On the other hand, if the thickness is larger than 0.8 μm, the hardness for securing the wear resistance cannot be secured even if the amount of Co is decreased to increase the hardness. In order to improve the wear resistance of the WC-based cemented carbide member, it is necessary to make the hardness harder than a certain level, and it is necessary to set the WC average particle size to 0.8 μm or less.
Co contributes to improving the sinterability, forms a binder phase, improves toughness, and has an effect of improving fracture resistance and fracture resistance. However, if the Co content is less than 3%, sufficient toughness and breakage resistance cannot be obtained, and if the Co content exceeds 13%, the hardness is remarkably reduced and the wear resistance is remarkably reduced. Therefore, the Co content is 3 to 13%. Preferably it is 5 to 10%.
In addition to the effect of suppressing grain growth of WC, Cr dissolves in the binder phase Co, improves its strength, and contributes to the improvement of corrosion resistance. If the Cr content is less than 0.3%, the intended improvement effect cannot be obtained, and if the Cr content exceeds 1%, V and W exist in a form that partially substitutes in the binder phase. The particle size of the double carbide phase containing Cr and Ta and / or Nb becomes coarse, and the toughness is remarkably lowered. Therefore, the Cr content is set to 0.3 to 1%.
V is an element that is most effective in suppressing grain growth of WC, and by adding V, the grain size of WC can be reduced to 0.8 μm or less. Further, it is a constituent element of a double carbide phase containing V, W, Cr, Ta and / or Nb in a form in which a part of the binder phase of the present invention is substituted, and by constituting these, hardness, wear resistance It contributes to the improvement. If the V content is less than 0.2%, it is difficult to sufficiently exert the grain growth suppressing action. Even if the particle size of the raw material WC powder is 0.8 μm, the WC particle size in the sintered body exceeds 0.8 μm due to grain growth during sintering. Further, when the V content exceeds 0.5%, the particle size of the double carbide phase containing V, W, Cr, Ta and / or Nb in a form in which a part of the binder phase is substituted becomes coarse, and the amount is also As it increases, the toughness is significantly reduced. Therefore, the V content is set to 0.2 to 0.5%.
Ta, Nb suppresses grain growth of WC, strengthens the binder phase by solid solution in the binder phase, and when using a WC-based cemented carbide member, the member is a work material or workpiece. Among the parts that come into contact with, etc., there is an effect of reducing the affinity with metals and alloys. As a result, adhesion, welding and the like are less likely to occur, wear and chipping due to welding and the like can be reduced, and the life of the member can be extended. Therefore, when the amount of Ta and / or Nb is 0%, the intended improvement effect cannot be obtained. Further, when the amount of Ta and / or Nb exceeds 1.5%, the particle size of the double carbide phase containing V, W, Cr, Ta and / or Nb in a form in which a part of the binder phase is replaced becomes coarse. As the amount increases, the toughness is significantly reduced. Therefore, the Ta and / or Nb content is more than 0 and 1.5% or less. More preferably, it is 0.2 to 1.2%.
The WC-based cemented carbide member of the present invention has a double carbide phase (V _x W _y Cr _z Ta _α Nb _β ) C containing V, W, Cr, Ta and / or Nb, provided that the double carbide phase The metal component is expressed as% by weight, and X + Y + Z + α + β = 100, 20 ≦ X ≦ 70, 20 ≦ Y ≦ 70, 1 ≦ Z ≦ 30, α + β = S, and 1 ≦ S ≦ 50. When X is less than 20%, the hardness of the double carbide phase is lowered and the effect of improving the wear resistance is reduced. On the other hand, if it exceeds 70%, the carbide phase becomes brittle and disadvantageous. Therefore, X is defined as 20 ≦ X ≦ 70. If Y is less than 20%, the hardness of the double carbide phase is lowered and the effect of improving the wear resistance is reduced. On the other hand, if it exceeds 70%, the carbide becomes brittle and disadvantageous. Therefore, Y is defined as 20 ≦ Y ≦ 70. If Z is less than 1%, the hardness of the double carbide phase is lowered, and the effect of improving the wear resistance is reduced. On the other hand, if it exceeds 30%, the carbide phase becomes brittle and disadvantageous. When S is less than 1%, the hardness of the double carbide phase is lowered, and the effect of improving the wear resistance is reduced. On the other hand, when it exceeds 50%, the double carbide phase becomes brittle and is inconvenient. Therefore, S is defined as 1 ≦ S ≦ 50. That is, when the weight percent of the metal component of the double carbide phase is within the scope of the present invention, the effect of improving the wear resistance is remarkably exhibited.
In the WC-based cemented carbide member of the present invention, a double carbide phase is present adjacent to the WC particles by structural observation with an electron microscope. Alternatively, a double carbide phase is present adjacent to the binder phase and the WC particles. This existence form is shown in the schematic diagram of FIG. In FIG. 1, the double carbide phase 1 exists adjacent to the WC particles 2 and the binder phase 3. It is presumed that the double carbide phase 1 containing V, W, Cr, Ta and / or Nb exists in a form in which a part of the binder phase 3 is replaced. Therefore, hereinafter, the existence form of the double carbide phase 1 is referred to as a substitution form. The substitution form of the present invention is such that the double carbide phase 1 is in the region between the WC particles and the WC particles, usually exists in a part of the region where the Co phase is present, and fills between the WC particles and the WC particles. Refers to the form. The presence of the double carbide phase 1 in a substituted form contributes to improvement in hardness and wear resistance. The substitution form of the double carbide phase 1 mentioned here may be a form in which the finely dispersed double carbide phase 4 is dispersed and distributed in the binder phase 3 as shown in the schematic diagram of FIG. 2 or at least a part of the surface of the WC particles 2. It is not a form like the coated surface coated carbide phase 5. As shown in FIG. 2, the finely dispersed double carbide phase 4 is finely dispersed and distributed in the binder phase 3 when the finely dispersed double carbide phase 4 is present in the Co phase existing in the region between the WC particles and the WC particles. It is a form that exists in a state surrounded by a Co phase. The form in which the surface-coated double carbide phase 5 covers at least a part of the surface of the WC particles is an extremely thin coating of about several atomic levels. Thus, the substitution form of the carbide phase 1 of the present invention is completely different from the form in which the finely dispersed double carbide phase 4 of the conventional example is dispersed and distributed, or the form coated with the surface-coated double carbide phase 5. However, in addition to the form in which the double carbide phase of the present invention replaces part of the binder phase, the form in which the double carbide phase containing V, W, Cr, Ta, and / or Nb covers at least part of the surface of the WC particles. It does not matter if it exists.
The particle size of the double carbide phase is 0.8 μm or less. If it exceeds 0.8 μm, it becomes equal to or larger than the particle size of WC, so that the toughness decreases. The area ratio M (%) of the double carbide phase is 0 <M <0.5. When the M value is 0, the effect is not obtained. When the M value is 0.5% or more, the amount of the double carbide phase increases, so that the toughness decreases.

  The addition of V, Cr, Ta, and Nb in the WC-based cemented carbide member of the present invention preferably uses a nitrogen-containing compound such as a nitride of V, Cr, Ta, or Nb and / or carbonitride. The reason is as follows. This is because the carbide phase containing V, W, Cr, Ta and / or Nb is in a form in which a part of the binder phase is substituted, and the average particle size can be 0.8 μm or less. When a compound containing nitrogen is used, a part of nitrogen generated by dissociation of these compounds during sintering is dissolved in a liquid phase mainly composed of Co. As a result, the standard free energy of formation of nitride is positive, and a stable nitride cannot be formed. That is, W that does not have an affinity for nitrogen is difficult to dissolve in Co. W is the main component of double carbide along with V, and the dissolution of N in Co results in faster crystallization and precipitation of the double carbide in the presence of the liquid phase in the cooling process. Crystallization and precipitation occur earlier than when N is not present in the binder phase. Therefore, growth by dissolution and precipitation of these compounds in the presence of a liquid phase is possible over a long period of time compared to the case where nitrogen is not present. It is not a finely distributed form, but a form in which the binder phase, which is a grown form, is substituted. In this case, the carbide phase containing V, W, Cr, Ta, and / or Nb may be a carbonitride phase containing nitrogen by taking in part of the nitrogen present in the liquid phase binder phase. Furthermore, in addition to the metal components of V, W, Cr, Ta, and Nb, one or more other metal components selected from the groups 4a, 5a, and 6a of the periodic table excluding V, W, Cr, Ta, and Nb are included. It may be contained in a trace amount.

  The WC-based cemented carbide member of the present invention includes drills, small-diameter drills, end mills, blade tip replaceable tips for end milling, blade tip replaceable tips for milling, blade tip replaceable tips for turning, metal saws, gear cutting tools, gun drills, reamers It is suitable for broaches, taps, etc., and the tool life is extended. More preferably, it is applied to a drill for printed circuit boards having a diameter of 0.2 mm or less, a router end mill for printed circuit boards having a diameter of 1.5 mm or less, or an end mill for metal processing having a diameter of 2 mm or less. This is because in these applications, in addition to the high toughness and high hardness inherent in the WC-based cemented carbide member, it corresponds to the improvement of the welding resistance and is effective in improving the tool life.

  The WC-based cemented carbide member of the present invention is preferably coated with a hard coating. The hard coating has one or more elements selected from periodic table 4a, 5a, 6a group elements, Al, Si as metal components, and is selected from C, N, O, B as nonmetal components. Contains one or more elements. The wear resistance of the member is further improved by the hard film having a high hardness, and a hard film-coated WC-based cemented carbide member having high toughness and breakage resistance can be obtained. More preferably, it is selected from (AlCr) (NO) -based film, (AlCrSi) (NO) -based film, (TiSi) (NO) -based film, (CrSi) (NB) -based film, and Ti (NBO) -based film. By adopting one or more kinds of monolayers and laminated films, oxidation resistance and lubrication performance can be further improved in addition to improvement of wear resistance.

The area ratio of the carbide phase containing V, W, Cr, Ta and / or Nb present in the WC-based cemented carbide can be measured by the following method. In the area ratio measurement method, the WC-base cemented carbide is polished, the polished surface is imaged, and the area of the carbide phase containing V, W, Cr, Ta and / or Nb existing in the WC-base cemented carbide is determined from the image. It is a method for measuring the rate, and is based on the procedures (1) to (4).
(1) The element V mapping element is specified by the element mapping function of the wavelength dispersion X-ray probe microanalyzer (hereinafter referred to as EPMA), and the line profile of the V element is collected. The observation magnification at this time is preferably 2000 to 3000 times.
(2) The form of the V-enriched portion is observed by observation with a transmission electron microscope (hereinafter referred to as TEM), and its dimensional value is measured. The observation sample at this time is a focused ion beam (hereinafter referred to as FIB) from the sample after confirming the location of the V-enriched part specified by EPMA with a field emission scanning microscope (hereinafter referred to as FE-SEM). Note: Create by cutting out by processing.
(3) The EPMA line profile of the V-enriched part in (1) is compared with the measurement size of the V-enriched part by TEM in (2), and a threshold value that is the count number of the line profile corresponding to the V-enriched part is set Set. Furthermore, it is preferable to repeat (1) to (3) in another V-concentrated phase, confirm that there is no variation in the threshold value, and set the threshold value as an average value thereof. Perform random EPMA mapping for multiple fields of view. For example, in the case of 2000 times, 30 μm × 30 μm is mapped as one visual field, and a visual field 100 μm apart is mapped at random by moving to the side of 130 μm and then performing the next mapping. This is repeated four times, mapping a total of 5 fields of view, then returning to the first field of view, moving down 130 μm from there, and mapping 5 fields of view in the same manner as above. By continuously performing these operations, a randomly selected multi-field mapping image is obtained. It is preferable to carry out 20 or more visual fields.
(4) A plurality of images obtained by the image means are binarized by the threshold value set in (3), and image processing is performed to calculate the area ratio of the V concentrated phase. The area ratio is obtained from a plurality of images, and an average value is preferably used.
Furthermore, the area ratios of other carbide phases can also be measured. For example, (V, Cr) C phase, TaC phase, (Ta, V) C phase and other carbides, measurement of the area ratio of a phase containing a trace amount of carbonitride, etc., TiC-based cermet trace amount carbide phase, carbonitride phase It can be applied to the measurement of the area ratio. Hereinafter, the present invention will be described in more detail with reference to examples. The embodiments show some examples of the present invention, and the present invention is not limited by the embodiments.

Example 1
WC powder having an average particle size of about 0.4 μm, Co, VC, VN, Cr ₃ C ₂ , Cr ₂ N, TaC, TaN, NbC, and NbN raw material powders having a mean particle diameter of about 0.4 μm are used as raw material powders. It mix | blended with the composition of. The powder was mixed with an attritor in alcohol containing a molding binder for 12 hours and granulated and dried with a spray dryer. The obtained granulated powder was extruded and formed into a green compact. This green compact was sintered at 1400 to 1450 ° C. in a vacuum atmosphere of 10 Pa to produce a sintered body. The obtained sintered body was polished, and the hardness was measured with a Rockwell A scale on the polished surface. Furthermore, the composition, form, size, and area ratio of the carbide containing V, W, Cr, Ta, and / or Nb were determined by the method shown in the present invention. The measurement results are shown in Table 1 together with the composition.

The average grain size of the WC of the sintered body is obtained by clarifying the grain boundaries by mirror-polishing the cross section of the sintered material, and then etching 0.5 minutes with Murakami reagent and 0.5 minutes with aqua regia. The image was calculated by enlarging an image taken at a magnification of 10 k using a scanning electron microscope (manufactured by Hitachi, S-4200, hereinafter referred to as SEM), and analyzing the image with an image analysis software. The WC average particle diameter measured by the above method was 0.3 to 0.4 μm. Next, these sintered bodies were processed to produce a ball end mill for machining a high hardness material of φ1.0 mm (R0.5 mm) from a round bar of φ4.0 × 45 mm. The obtained end mill was formed by arc ion plating with a (TiAl) N film of 3.0 μm and a (TiSi) N film of 1.0 μm. Using these end mills, bottom surface cutting was performed under the following conditions, and evaluation was performed based on the cutting distance until the blade flank wear amount was 0.015 mm. The results are also shown in Table 1.
(Cutting specifications 1)
Work material: SKD11 (Heat treatment material hardness HRC62)
Number of revolutions: 12,000 revolutions / minute
Cutting depth: 0.07mm in the radial direction, 0.21mm in the depth direction

  Any of the end mills of Invention Examples 1 to 9 had a cutting life of 25 m or more based on the above-mentioned life criteria. On the other hand, in Comparative Examples 10 and 11 in which the Co amount is outside the range defined by the present invention, Comparative Example 10 is inferior in sinterability because the Co amount is too small, and Comparative Example 11 has a hardness of 93 because the Co amount is too large. It became lower than 0.0, and the cutting distance on the above-mentioned life standard at the time of end mill cutting was shortened to 10 m or less. As for Comparative Examples 12 and 13 in which the Cr amount was outside the range defined by the present invention, Comparative Example 12 had a small Cr amount, resulting in a low hardness and a shortenable cutting distance. In Comparative Example 13, the particle size and area ratio of the carbide containing V, W, Cr, Ta, and / or Nb were increased, so that the toughness was lowered and the cutting distance was shortened by chipping. In Comparative Examples 14, 15, and 16 in which the V amount is outside the range defined by the present invention, in Comparative Example 14, where the V amount is small, WC particles grow, the hardness decreases, and the cutting distance also decreases because V is small. . In Comparative Examples 15 and 16 having a large amount of V, the particle size and area ratio of carbide containing V, W, Cr, Ta, and / or Nb were increased, so that the toughness was lowered and the cutting distance was shortened by chipping. In Comparative Examples 17 and 18 in which the amount of Ta and / or Nb is outside the range specified in the present invention, Comparative Example 17 not containing Ta or Nb is low in hardness and wear of the work material on the cutting edge is caused. The cutting distance was shortened because of the rapid progress of. On the other hand, in Example 18 with a large amount of Ta and / or Nb, the particle size and area ratio of the double carbide phase were increased, so that the toughness was reduced and the cutting distance was shortened by chipping. The comparative example 19 using the compound which does not contain nitrogen as an addition method of V, Cr, Ta, Nb does not partially replace the binder phase with the carbide containing V, W, Cr, Ta and / or Nb, Since it was dispersed in the binder phase, the amount of addition was the same and the hardness was lower and the cutting distance was shorter than in Example 7 of the present invention in which the compound containing nitrogen was added. Further, the composition of the carbide phase containing V, W, Cr, Ta, and / or Nb was also out of the scope of the present invention in Comparative Examples 10 to 17. From these, the superiority of the end mill of the present invention example in the end mill cutting of a hard work material is clear.

(Example 2)
As the raw material powder, WC powder having an average particle size of about 0.6 μm and the same raw material powder as in Example 1 were blended in the composition shown in Table 2, and after mixing for 12 hours in an attritor in alcohol containing a molding binder, Granulated and dried with a spray dryer. The obtained granulated powder was extruded and press-molded to obtain a green compact. These green compacts were sintered at 1400 to 1450 ° C. in a vacuum atmosphere of 10 Pa, and then pressurized with gas at 4.9 MPa while maintaining the same temperature to produce sintered bodies. Various measurements were performed on the obtained sintered body in the same manner as in Example 1. The measurement results are shown in Table 2 together with the composition.

All the WC average particle diameters of the sintered compact were 0.3-0.6 micrometer. Next, these sintered bodies were processed to prepare a drill for a printed circuit board having a diameter of 0.1 mm from a round bar having a diameter of 2.0 mm × 31.8 mm. Using these drills, drilling was carried out under the following conditions, and the reduction in diameter at a position of 0.1 mm from the cutting edge at the time of drilling 2000 holes was evaluated. The results are shown in Table 2.
(Cutting specifications 2)
Substrate: 0.1 mmt, double-sided plate, copper thickness 5 μm × 6 sheets stacked Rotation speed: 250,000 rotations / min

  As shown in Examples 20 to 25 of the present invention, the diameter reduction of the drill of the present invention was 10 μm or less, and the wear amount was small. On the other hand, in Comparative Examples 26 and 27 in which the Cr amount was outside the range specified in the present invention, Comparative Example 26 had low hardness because grain growth occurred because the Cr amount was small, and the diameter reduction amount was as large as 20 μm. In Comparative Example 27, since the amount of Cr was too large, the particle size and area ratio of the carbide containing V, W, Cr, Ta, and / or Nb were increased, and the toughness was decreased, so that the diameter loss was increased by chipping. In Comparative Examples 28 and 29 in which the V amount is outside the range defined by the present invention, in Comparative Example 28 where the V amount is small, WC particles grow because the V is small, the hardness becomes low, the wear amount is large, and the diameter loss is large. became. In Comparative Example 29 with a large amount of V, the particle size and area ratio of carbides containing V, W, Cr, Ta, and / or Nb were increased, so that chipping was increased due to a decrease in toughness, and the diameter reduction was increased. In Comparative Examples 30 and 31 in which the amount of Ta and / or Nb is outside the range specified in the present invention, Comparative Example 30 not containing Ta and Nb is low in hardness and wear of the work material on the cutting edge is caused by wear. The cutting distance was shortened because of the rapid progress of. On the other hand, in Example 31 with a large amount of Ta and / or Nb, the particle size and area ratio of the double carbide phase were increased, so that the toughness was reduced and the cutting distance was shortened by chipping. In Comparative Example 32 using a compound containing no nitrogen as a method for adding V, Cr, Ta, and Nb, the carbide containing V, W, Cr, Ta, and / or Nb is not in the form of the present invention, but in the binder phase. Because of the dispersion, the hardness was lower than that of Example 24 in which the same amount was added and the compound containing nitrogen was added. Further, the composition of the carbide phase containing V, W, Cr, Ta and / or Nb was also out of the scope of the present invention in Comparative Examples 26 to 32. From these, the superiority of the drill of the present invention is clear in drilling with a small diameter drill for printed circuit boards.

(Example 3)
As raw material powder, WC powder having an average particle size of about 0.4 μm and the same raw material powder as in Example 1 were mixed in the composition shown in Table 3, and mixed for 12 hours with an attritor in alcohol containing a molding binder. Granulated and dried with a spray dryer. The obtained granulated powder was extruded and press-molded to obtain a green compact. These green compacts were sintered at 1400 to 1450 ° C. in a vacuum atmosphere of 10 Pa, and then pressurized with gas at 4.9 MPa while maintaining the same temperature to produce sintered bodies. Various measurements were performed on the obtained sintered body in the same manner as in Example 1. The measurement results are shown in Table 3 together with the composition.

These sintered bodies had a WC average particle diameter of 0.3 to 0.4 μm. These sintered bodies were processed to produce a router end mill for a printed circuit board having a diameter of 1.5 mm from a round bar having a diameter of 3.175 × 38 mm. Grooving was performed using these router end mills, and the diameter loss after cutting 20 m was evaluated. The results are also shown in Table 3.
(Cutting specifications 3)
Substrate: 1.6 mmt, no copper, FR4 × 2 sheets stacked Rotation speed: 35,000 rev / min Feed amount: 1000 mm / min,
Z-axis cutting speed: 200 mm / min

  The router end mills of Invention Examples 33 to 35 all showed good wear resistance properties with a diameter loss of 10 μm or less. On the other hand, the router end mill of Comparative Example 36 did not contain nitrogen in the additive compounds of V, Cr, Ta, and Nb. Therefore, the carbide containing V, W, Cr, Ta and / or Nb does not partially substitute the binder phase but disperses in the binder phase. Compared with the inventive examples 33 to 35, the hardness was lowered, the wear amount was increased, and the diameter loss was increased to 23 μm. From these, the superiority of the router end mill of the present invention in the grooving by a small diameter router end mill for printed circuit boards is clear.

FIG. 1 shows a schematic view of the form of a double carbide containing V, W, Cr, Ta and / or Nb of the present invention. FIG. 2 shows a schematic diagram of a form of a double carbide containing V, W, Cr, Ta and / or Nb in the conventional example.

Explanation of symbols

1: Double carbide phase containing V, W, Cr, Ta and / or Nb 2: WC particles 3: Bonded phase 4: Finely dispersed double carbide phase 5: Surface-coated double carbide phase

Claims (7)

The average particle diameter of WC is 0.8 μm or less, and by weight%, the Co content is 3 ≦ Co ≦ 13%, the Cr content is 0.3 ≦ Cr ≦ 1.0, and the V content is 0. .2 ≦ V ≦ 0.5, Ta and / or Nb content is 0 <(Ta and / or Nb) ≦ 1.5, the balance is WC-based cemented carbide composed of WC and inevitable impurities, The WC-based cemented carbide includes a binder phase mainly composed of Co, a hard phase mainly composed of WC, and a double carbide phase containing V, W, Cr, Ta and / or Nb having an average particle size of 0.8 μm or less. _{(V x W y Cr z Ta} α Nb β) has and C, and provided that the metal component of said plurality carbide phases in wt%, X + Y + Z + α + β = 100,20 ≦ X ≦ 70,20 ≦ Y ≦ 70,1 ≦ When Z ≦ 30 and α + β = S, 1 ≦ S ≦ 50, and the double carbide phase is adjacent to the hard phase or the bond And present adjacent the rigid phase, the area ratio M (%) of said plurality carbide phase, 0 <WC based cemented carbide member which is a M <0.5. The WC-based cemented carbide member according to claim 1, wherein the hardness of the WC-based cemented carbide member on the Rockwell A scale is 93 or more and 95 or less. The WC-base cemented carbide member according to claim 1 or 2, wherein the WC-base cemented carbide member is a drill, a small diameter drill, an end mill, an end mill cutting edge replacement tip, a milling cutting edge replacement tip, a turning cutting edge replacement. A WC-based cemented carbide member, which is one type selected from the group consisting of a die tip, a metal saw, a gear cutting tool, a gun drill, a reamer, a broach and a tap. 4. The WC-based cemented carbide member according to claim 3, wherein the end mill is a metal working end mill having a diameter of 2 mm or less. 4. The WC-based cemented carbide member according to claim 3, wherein the drill is a printed circuit board drill having a diameter of 0.2 mm or less. 5. The WC-based cemented carbide member according to claim 4, wherein the end mill is a router end mill for a printed circuit board having a diameter of 1.5 mm or less. The WC-based cemented carbide member according to any one of claims 1 to 6, wherein the WC-based cemented carbide member is coated with a hard coating, and the hard coating is composed of a metal component and a periodic table 4a, 5a, 6a group element. Coated WC-base cemented carbide having one or more elements selected from Al, Si, and one or more elements selected from C, N, O, and B as non-metallic components Element.

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