JP6957395B2 - Ceramic members and tools using them, cutting tools - Google Patents

Description

The present disclosure relates to a ceramic member, a tool using the ceramic member, and a cutting tool.

Since the ceramic member is excellent in heat resistance and hardness, it is used as a tool used for cutting, for example. In this tool, for example, as described in Patent Documents 1 to 3, _{a ceramic member containing alumina (Al 2} O ₃ ) and tungsten carbide (WC) is used.

Special Table No. 7-502070 Japanese Unexamined Patent Publication No. 2016-113320 International release 2015/01/391

When the alumina and tungsten carbide contained in the ceramic members described in Patent Documents 1 to 3 are compared, alumina has a lower bending force than tungsten carbide. Therefore, when a strong load is applied to the ceramic member, such as during cutting, cracks may occur in the alumina. If this crack extends for a long time, the strength of the ceramic member may decrease. Therefore, a ceramic member having high toughness is required.

The ceramic member of the present disclosure is a ceramic member composed of a ceramic substrate having a plurality of first particles containing tungsten and carbon in a total amount of 90% by mass or more, and a plurality of second particles containing aluminum and oxygen. .. The substrate further has a columnar body containing less than 90% by mass of tungsten and carbon in total and containing a plurality of third particles containing chromium and titanium. The columnar body has an average major axis length of 40 μm or more in a cross section orthogonal to the surface of the substrate. The columnar body contains a plurality of particles in a cross section orthogonal to the surface of the substrate, and the particles are in the first form composed of only a third particle, in a cross section orthogonal to the surface of the substrate. A second form in which the first particles are surrounded by a plurality of the third particles, and a third form in which the second particles are surrounded by a plurality of the third particles in a cross section orthogonal to the surface of the substrate. Of these, it has at least one form.

Further, the tool of the present disclosure includes the above-mentioned ceramic member.

Further, the cutting tool of the present disclosure includes a holder extending from the first end toward the second end and having a pocket on the first end side, and the above-mentioned tool located in the pocket.

The ceramic member of the present disclosure has high fracture toughness. Tools and cutting tools using this ceramic member have excellent fracture resistance.

It is a perspective view which shows an example of the ceramic member of this disclosure. It is a schematic diagram in the cross section orthogonal to the surface of the ceramic member of this disclosure. It is a schematic diagram which shows an example of the cutting tool of this disclosure.

Hereinafter, the ceramic members, tools, and cutting tools of the present disclosure will be described in detail with reference to the drawings. However, for convenience of explanation, each figure referred to below is a simplified representation of only the main members necessary for explaining each embodiment. Therefore, the ceramic member may include any component not shown in each referenced figure. Further, the dimensions of the members in each drawing do not faithfully represent the actual dimensions of the constituent members, the dimensional ratio of each member, and the like.

FIG. 1 shows an example of the ceramic member 1 of the present disclosure in a perspective view. Since the ceramic member 1 is made of a ceramic substrate, reference numerals 4 indicating the substrate are shown side by side in FIG. 1, and since the ceramic member 1 can be used as a tool, FIG. 1 shows a tool. It can be said that it is a perspective view showing 3.

The tool 3 is an example of a cutting insert with a replaceable cutting edge, which is used by being attached to a predetermined position at the tip of a holder (not shown).

The tool 3 has a polygonal plate shape, and is a cutting tool located at least a part of a portion where the first surface 5, the second surface 7 adjacent to the first surface 5, and the first surface 5 and the second surface 7 intersect. It has a blade 9. In FIG. 1, the upper surface corresponds to the first surface 5, and the side surface corresponds to the second surface 7.

The tool 3 has a polygonal plate-shaped substrate 4. The tool 3 may have a coating film (not shown) located on the surface of the substrate 4. The size of the tool 3 is not particularly limited, but for example, the length of one side of the first surface 5 is set to about 5 to 20 mm, and the surface (lower surface) located on the opposite side of the first surface 5 The height up to the first surface 5 based on the above is set to about 1 to 20 mm. The thickness of the coating film is not particularly limited, but is set to, for example, 3 to 25 μm.

FIG. 2 shows an example of a schematic view in a cross section orthogonal to the surface of the ceramic member 1 of the present disclosure. In FIG. 2, a plurality of first particles 21 and second particles 23 are present in a portion other than the columnar body 27, but the description is omitted because the figure becomes complicated. Further, in the following description, the case where a cross section orthogonal to the surface is viewed may be simply referred to as a cross-sectional view.

The ceramic member 1 of the present disclosure is a ceramic member 1 composed of a substrate 4 having a plurality of first particles 21 containing tungsten and carbon in a total of 90% by mass or more and a plurality of second particles 23 containing aluminum and oxygen. Is. The substrate 4 further has a columnar body 27 containing less than 90% by mass of tungsten and carbon in total and containing a plurality of third particles 25 containing chromium and titanium. Further, the columnar body 27 has an average major axis length of 40 μm or more in a cross section orthogonal to the surface of the substrate 4. In FIG. 2, in the columnar body 27, the first particle 21 is painted black and the third particle 23 is shown in white in order to clarify the discrimination.

Since the ceramic member 1 of the present disclosure has a columnar body 27, the columnar body 27 can suppress the growth of cracks, and thus has high fracture toughness.

The first particle 21 may be tungsten carbide (WC). Further, the first particle 21 may contain another element in the WC. The first particle 21 may have a composition formula represented by W ₂ C. The first particle 21 may further have chromium. As described above, when the first particle 21 contains chromium, the corrosion resistance of the ceramic member 1 is improved. The first particle 21 has a particle size of about 0.2 to 10 μm.

The second particle 23 may be aluminum oxide (Al ₂ O ₃ ). Examples of the aluminum oxide in the second particle 23 include κ-Al ₂ O ₃ and α-Al ₂ O ₃ . Further, aluminum oxide may contain other elements. The second particle 23 may contain at least one of magnesium (Mg), calcium (Ca), strontium (Sr), silicon (Si), and an element of Group 3a of the Periodic Table. The second particle 23 has a particle size of about 0.2 to 10 μm.

The first particle 21 and the second particle 23 are not limited to the above configuration, and may contain other components. For example, the first particle 21 may contain cobalt (Co) or nickel (Ni), and may contain titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), and niobium (Nb). ), Tanta (Ta) and molybdenum (Mo) compounds (oxides, carbides and nitrides) may be contained.

The content ratio of tungsten in the first particle 21 may be, for example, about 90 to 95% by mass when converted to tungsten carbide. The content ratio of chromium in the first particle 21 may be, for example, about 1.6 to 8% by mass. The content ratio of aluminum oxide in the second particle 23 may be, for example, about 80 to 98% by mass.

The third particle 25 has tungsten, chromium, titanium and carbon. The total of tungsten and carbon in the third particle 25 is less than 90% by mass. The ratios of tungsten, chromium, and titanium in the third particle 25 are W: 40 to 70, Cr: 20 to 40, and Ti: 5 to 30 in terms of mass ratio when the total of W, Cr, and Ti is 100. You may. Further, the third particle 25 may contain aluminum (Al). The third particle 25 has, for example, a particle size of about 0.2 to 10 μm.

The columnar body 27 is a collection of a plurality of third particles 25, and the outer shape of the columnar body 27 in a cross-sectional view may not be straight or may have irregularities. The first particles 21 and the second particles 23 may be present in the recesses of the columnar body 27.

Further, in the columnar body 27, the first particles 21 may be surrounded by the third particles 25 in a cross section orthogonal to the surface of the substrate. When particles having different compositions are present as described above, residual stress is generated in the columnar body 27 due to the difference in thermal expansion between the first particle 21 and the third particle 25, and the columnar body 27 is strengthened. In the columnar body 27, the second particles 23 may be surrounded by the third particles 25 in a cross section orthogonal to the surface of the substrate. In this case as well, the same effect can be obtained.

The columnar body 27 may be composed of only the third particles in the cross section orthogonal to the surface of the substrate 4.

In the cross section orthogonal to the surface of the substrate 4, the average aspect ratio of the columnar body 27 may be 4 to 15. Within such a range, the effect of suppressing the growth of cracks becomes high. In the cross section orthogonal to the surface of the substrate 4, the average major axis length of the columnar body 27 may be 60 to 190 μm. Having a size in such a range has a great effect of suppressing the growth of cracks. Further, in the cross section orthogonal to the surface of the substrate 4, the average minor axis length of the columnar body 27 may be 3 to 10 μm. If the average minor axis length of the columnar body 27 is within such a range, the columnar body 27 is less likely to be destroyed by the growth of cracks. Within such a range, the ceramic member 1 has excellent fracture toughness and strength.

The columnar body 27 may be present in a surface region of up to 2 mm from the surface of the substrate 4 toward the inside of the substrate 4. Further, the columnar body 27 may be present in the surface region more than the internal region inside the surface region. When the ceramic member 1 is used as a structural member, a force for breaking the ceramic member 1 is applied from the surface of the ceramic member 1. Further, when the ceramic member 1 is used as the tool 3, friction or force is applied to the surface of the ceramic member 1. Therefore, if the surface of the ceramic member 1 has high fracture toughness, it tends to face friction and force. Therefore, the columnar body 27 may exist in the surface region of the ceramic member 1. Further, it may be present in the surface region more than the internal region.

The tool 3 of the present disclosure uses the above-mentioned ceramic member 1 as the base 4 of the tool 3. The tool 3 using such a ceramic member 1 as the substrate 4 is excellent in fracture resistance because the fracture toughness of the substrate 4 is high.

Further, the tool 3 of the present disclosure may have a coating film on the surface of the ceramic member 1, or may have a coating film containing TiAlN as a main component. The main component means a component of 80% by mass or more. The coating film is provided for the purpose of suppressing wear of the tool 3, and examples thereof include titanium compounds, alumina, and diamond. Examples of the titanium compound include TiC, TiN, TiCN and TiCNO. By coating the surface of the substrate 4 with the above material using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, a coating film can be provided on the surface of the substrate 4. The coating film in the tool 3 of the present disclosure may be formed by PVD.

The composition of each particle in cross-sectional view can be confirmed by, for example, a scanning electron microscope (SEM) image after mirror-finishing a cross section orthogonal to the surface of the substrate 4. Elemental analysis of each particle can be evaluated, for example, by the SEM-EDX method using an energy dispersive X-ray spectrometer (EDX) attached to a scanning electron microscope. Further, confirmation of the contained components constituting each particle can be evaluated by using, for example, an X-ray diffraction (XRD) method.

Tungsten and carbon are confirmed in a certain particle by the above measuring method, and if the total of tungsten and carbon is 90% by mass or more, the particle is the first particle 21. Further, if the second particle aluminum and oxygen are confirmed in a certain particle, the particle is the second particle 23. Further, if tungsten, chromium, titanium and carbon are confirmed in a certain particle and the total of tungsten and carbon is less than 90% by mass, the particle is the third particle 25.

Next, the cutting tool of the present disclosure will be described with reference to the drawings.

As shown in FIG. 3, the cutting tool 101 of the present disclosure is, for example, a rod-shaped body extending from a first end (upper end in FIG. 3) to a second end (lower end in FIG. 3). As shown in FIG. 3, the cutting tool 101 includes a holder 105 having a pocket 103 on the first end side (tip side) and the above-mentioned tool 3 located in the pocket 103. Since the cutting tool 101 includes the tool 3 having excellent fracture resistance, stable cutting can be performed for a long period of time.

The pocket 103 is a portion on which the tool 1 is mounted, and has a seating surface parallel to the lower surface of the holder 105 and a restraining side surface inclined with respect to the seating surface. Further, the pocket 103 is open on the first end side of the holder 105.

The tool 3 is located in the pocket 103. At this time, the lower surface of the tool 3 may be in direct contact with the pocket 103, or a sheet (not shown) may be sandwiched between the tool 3 and the pocket 103.

The tool 3 is attached to the holder 105 so that at least a part of the portion used as the cutting edge 9 at the ridge line where the first surface 5 and the second surface 7 intersect protrudes outward from the holder 105. In this embodiment, the tool 3 is attached to the holder 105 by the fixing screw 107. That is, by inserting the fixing screw 107 into the through hole 17 of the tool 3, inserting the tip of the fixing screw 107 into the screw hole (not shown) formed in the pocket 103, and screwing the screw portions together, the tool is used. 3 is attached to the holder 105.

As the material of the holder 105, steel, cast iron, or the like can be used. Among these members, steel having high toughness may be used.

In this embodiment, a cutting tool used for so-called turning is illustrated. Examples of the turning process include inner diameter processing, outer diameter processing, grooving processing, end face processing and the like. The cutting tool is not limited to the one used for turning. For example, the tool 1 of the above embodiment may be used as the cutting tool used for milling.

Hereinafter, a method for manufacturing the ceramic member (base) of the present disclosure will be described.

First, a powder of an inorganic material that is a raw material of a substrate is prepared. As a powder of tungsten carbide constituting the first particles, the average particle diameter is prepared WC powder or _{W 2} C powder 0.1-2 .mu.m. Incidentally, these WC powders or W _{2 C} powder, also is the raw material of the third particles to be described later.

As the aluminum oxide powder constituting the second particle, 0.1 to ₂ μm Al 2 O ₃ powder is prepared. At this time, when the average particle size of the _{Al 2} O _{3 powder is larger than the WC particles and the W 2} C particles, the average particle size of the second particles on the substrate is larger than the average particle size of the first particles and the third particles. Easy to make large.

As the raw material powder constituting the third particle, chromium carbide powder (Cr ₃ C ₂ ) having an average particle size of 1 to 5 μm and titanium oxide powder having an average particle size of 0.1 to 2 μm are prepared. As the chromium carbide powder, Cr ₇ C ₃ or Cr ₂₃ C ₆ powder may be used, and titanium carbide may be used as the titanium raw material. The tungsten constituting the third particle may be common to the raw material powder of the first particle.

Such raw material powder is, for example, in the ratio of WC powder: 75% by mass, Al ₂ O ₃ powder: 20% by mass, Cr ₃ C ₂ powder: 4.5% by mass, and TiO ₂ powder: 0.5% by mass. The mixture is mixed, and if necessary, a binder or the like is added to prepare a molded product.

Next, this molded product is fired. In order to produce the substrate of the present disclosure, the following firing conditions may be used.

For example, it is held at a temperature of 1800 to 1950 ° C. for 6 hours or more. The atmosphere at the time of firing is a reducing atmosphere in which an inert gas such as argon (Ar) and neon (Ne) or carbon is present. _{Here, by adding CO 2} gas to the atmospheric gas, a columnar body is formed.

Further, _{even when CO 2} gas is not used, firing is performed for a long time of 6 hours or more even excluding the time required for heating and cooling under the sintering temperature condition of 1800 to 1950 ° C., which is higher than the temperature at which alumina decomposes. Therefore, a columnar body is formed by oxidizing chromium carbide. The ceramic member of the present disclosure can be obtained by firing a molded product having the above composition under such firing conditions.

Increasing the content of the powder as a raw material for the third particles contained in the molded product increases the proportion of the third particles contained in the ceramic member. Further, when the holding time at the time of firing is lengthened, the average major axis length of the columnar body tends to be long.

Further, even if the firing temperature is raised, the average major axis length of the columnar body tends to be long.

When the particle size of the powder used as the raw material of the first particles is smaller than the particle size of the powder used as the raw material of the third particles, the first particles are likely to be surrounded inside the columnar body in a cross-sectional view.

Further, when the particle size of the powder used as the raw material of the second particles is smaller than the particle size of the powder used as the raw material of the third particles, the second particles are likely to be surrounded inside the columnar body in a cross-sectional view. ..

_{Further, if the amount of CO 2} gas contained in the atmosphere at the time of firing is increased, the third particles are likely to be present throughout the ceramic member. _{When the amount of CO 2} gas contained in the atmosphere at the time of firing is reduced, the third particles are likely to be present in the surface region of 2 mm from the surface of the ceramic member.

_{As described above, by adjusting the amount of CO 2} gas in the atmosphere at the time of firing, it is possible to obtain a ceramic member in which more third particles are present in the surface region of the ceramic member than in the inner region of the ceramic member.

_{The amount of CO 2} gas contained in the atmosphere may be, for example, a CO ₂ partial pressure in the range of 0.1 KPa to 1 KPa.

The substrates of the present disclosure have higher fracture toughness than those having the same composition but containing no columnar body. By having such high fracture toughness, it is excellent as a ceramic member. Further, when the substrate is used as a tool in a predetermined shape, it has excellent toughness and therefore has excellent fracture resistance.

After that, the surface of the produced substrate may be polished or honed. If polishing and honing are not required, they may be omitted.

Then, by coating the surface of the produced substrate with a titanium compound or the like by a chemical vapor deposition method or a physical vapor deposition method, a tool having the substrate and a coating film is produced. If this coating step is omitted, a tool having only a substrate is produced. When this coating film is a PVD film, it has excellent fracture resistance.

The ceramic member of the present disclosure, a tool using the same, and a cutting tool are not limited to the above-described embodiments, and various improvements and changes may be made without departing from the gist of the present disclosure.

1 ... Ceramic member 3 ... Tool 4 ... Base 5 ... First surface 7 ... Second surface 9 ... Cutting edge 17 ... Through hole 21 ... First particle 23 ... 2nd particle 25 ... 3rd particle 27 ... Columnar body 101 ... Cutting tool 103 ... Pocket 105 ... Holder 107 ... Fixing screw

Claims (9)

A plurality of first particles containing a total of 90% by mass or more of tungsten and carbon, and
A ceramic member composed of a ceramic substrate having a plurality of second particles containing aluminum and oxygen.
The substrate is
Further, it has a columnar body containing less than 90% by mass of tungsten and carbon in total and containing a plurality of third particles containing chromium and titanium.
Columnar body state, and are an average major axis length of 40μm or more in a cross section perpendicular to the surface of the substrate,
The columnar body is
A first form, which contains a plurality of particles in a cross section orthogonal to the surface of the substrate, and the particles are composed of only a third particle.
A second form in which the first particle is surrounded by a plurality of the third particles in a cross section orthogonal to the surface of the substrate.
A ceramic member having at least one of the third forms in which the second particles are surrounded by a plurality of the third particles in a cross section orthogonal to the surface of the substrate. The ceramic member according to claim 1, wherein the columnar body has an average aspect ratio of 4 to 15 in a cross section orthogonal to the surface of the substrate. The ceramic member according to claim 1 or 2 , wherein the columnar body has an average major axis length of 60 to 90 μm in a cross section orthogonal to the surface of the substrate. The ceramic member according to any one of claims 1 to 3 , wherein the columnar body exists in a surface region of up to 2 mm from the surface of the substrate toward the inside of the substrate. The ceramic member according to claim 4 , wherein the columnar body is present in the surface region more than the surface region inside the substrate. A tool comprising the ceramic member according to any one of claims 1 to 5. The tool according to claim 6 , wherein a coating film is provided on the surface of the ceramic member. The tool according to claim 7 , wherein the coating film includes a coating film containing TiAlN as a main component. A holder that extends from the first end toward the second end and has a pocket on the first end side.
A cutting tool comprising the tool according to any one of claims 6 to 8 located in the pocket.

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