JP2001019537A - Ceramic member with edge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic member with edges, capable of being produced while reducing chipping, having improved sharpness, and capable of providing extremely improved processing accuracy by constituting the ceramic member of an alumina-based ceramic material containing a specific vol.% or more of alumina-based phase, allowing the member to satisfy a specified relation between the average particle diameter and the fractional toughness value, forming the edge parts on the outer surface of the member, and forming one of them into a sharp edge part. SOLUTION: This ceramic member contains >=20 vol.% alumina-based phase. The average particle diameter d (μm) and the fractional toughness value KC (MPa.m1/2) satisfy the formula KC/(dA)>=3.5 [exponential number A is within the range of (-0.27)-(-0.20)]. One or more edge parts like ridge lines, formed at the crossing positions of two edge-forming surfaces are formed on the outer surface of the member, and one thereof has the edge tip part having <=0.3 mm width, and shown on the cross section when being cut by an arbitrary face orthogonal to the ridge line direction. When the before formula is satisfied, the maximum height of a surface roughness can be regulated so as to be <=50 μm, even if the sharp edge having 0.3 mm width at the tip part is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an edged ceramic member and a method for manufacturing the same.

[0002]

2. Description of the Related Art Alumina-based ceramics have been applied to tools and mechanical parts as ceramic materials having excellent strength and heat resistance. In addition, such an alumina-based ceramic can enhance various properties originally possessed by alumina by adding an appropriate second phase to the alumina-based phase, and can impart new properties. Therefore, a wider application is possible. For example,
Japanese Patent No. 2616795 discloses that alumina is 20 to 40.
There is disclosed a technique capable of increasing the transverse rupture strength to 1.5 times or more by including TiC in a weight percentage. Also, Japanese Patent No. 26000082 discloses a technique capable of enabling electric discharge machining by including conductive particles.

[0003]

However, in the zirconia-based ceramic member as described above, even if various characteristics can be improved or new characteristics can be provided at the laboratory level, troubles occur at the stage of commercialization. Often causes. In particular, for cutting tools and mold-related parts (punches, dies, etc.) that require sharp edges, even ceramics with excellent bending strength and hardness, if the edges are chipped, the processed surface of the product Since the finish and dimensional accuracy of the product deteriorate, burrs are generated on the work, or the ceramic member itself is damaged, it cannot be used as a product at all.

[0004] In the case of a ceramic member requiring a sharp edge, such as a cutting tool, a punch or a die for a mold as described above, it is necessary to finally perform edge finishing by precise polishing. However, in the case of a conventional alumina-based ceramic member, there is a problem that chipping easily occurs at the edge portion during the edge polishing. Therefore, in the past, in order to avoid the occurrence of large chipping, a method of sacrificing the sharpness of the edge part to some extent has been adopted, but with this, it is difficult to obtain good processing accuracy, and rather, it is difficult to obtain a sharp edge. Attempting to pursue the finish can lead to severe chipping and the need to abandon product manufacturing.

SUMMARY OF THE INVENTION An object of the present invention is to suppress the occurrence of chipping extremely effectively, thereby making it possible to finish the edge portion to a sharpness which could not be achieved conventionally, and thereby to improve the processing accuracy of punching and the like using the same. An object of the present invention is to provide a ceramic member with an edge which can be greatly improved and a method for manufacturing the same.

[0006]

Means for Solving the Problems and Action / Effect In order to solve the above-mentioned problems, the edged ceramic member of the present invention is made of an alumina-based ceramic material containing 20% by volume or more of an alumina-based phase. In addition, the average particle diameter is d (unit: μm), and the fracture toughness value is KC (unit: MP).
a · m ^1/2 ), -0.27 to -0.20
KC / (d ^A ) ≧ 3.5 ‥‥‥ (1) using an index value A set in the range of One or more edges appearing in the form of a ridge at the intersection are formed, and at least one of the edges is an edge tip that appears at a cut when cut along any plane perpendicular to the ridge direction. Width of 0.3
mm or less, and is formed as a sharp edge portion.

In the present invention, the average particle diameter d of the alumina-based ceramic material is determined by mirror-polishing the surface of the material by surface grinding and lapping, and then performing thermal etching in a normal pressure nitrogen atmosphere at 1300 ° C. and observing by SEM (magnification). 5,000 times) and the value obtained on the observed image as follows. In other words, the crystal grains appearing on the observation image are approximated by a circle to obtain the diameter distribution, and further, the Schwarts-S
Approximate sphere particle size distribution is obtained by applying the altykov method (however, the particle size class width is assumed to be 0.1 μm), and the median of the particle size classes whose cumulative frequency from the small particle size side is 50% is averaged. Let the particle size be d. The fracture toughness value is JIS: R160
7 means the value measured by the SEPB method. In this specification, the term "alumina-based phase" refers to a phase containing alumina as a main component (50% by weight or more).

[0008] Since the above-mentioned alumina-based ceramics are liable to cause chipping, conventionally, in ordinary polishing,
The width of the edge tip is 0.3 mm or less (particularly 0.15 mm
It has been considered impossible to form a sharp edge portion as described below. However, as a result of diligent studies by the present inventors, when the average grain size d of the ceramic and the fracture toughness value Kc satisfy a specific relationship, unexpectedly, chipping may occur even if such a sharp edge is formed. Have been found to be extremely effectively prevented, and the present invention has been completed. That is, the ceramic member with an edge of the present invention is made of alumina-based ceramic, and is -0.27 or more, and -0.0.
When defining the index value A at 20 or less range, when the value of B being defined by ^{KC / (d A) = B} ‥‥‥ (2) is 3.5 or more, the chipping resistance Very good ceramic members with edges are realized. As a result, it is possible to greatly improve the processing accuracy of cutting, punching, deep drawing, and the like using this.

When the value of the index value A is -0.27 to -0.0.
Outside the range of 20, the value of B in equation (2) no longer reflects the difficulty of chipping of an alumina-based ceramic material containing 20% by volume or more of an alumina-based phase, and serves as an index indicating chipping resistance. Lose meaning. The value of B is essential to be 3.5 or more, but the larger the value, the more advantageous from the viewpoint of ensuring chipping resistance. However, it is difficult to set the crystal grain size of the material constituent phase to 0.1 μm or less due to a request in the production method (particularly, the preparation of the raw material powder). However, in the present invention, this is not set as the upper limit. In order to increase chipping resistance, the value of B is preferably 4 or more, and more preferably 4.5 or more. As a result, when the value of B becomes large, it becomes possible to finish the edge portion more sharply. For example, as a more desirable value, the edge tip width is preferably less than 0.1 mm.

[0010] The sharp edge portion has a maximum height Rmax of the edge tip surface roughness measured in the direction of the ridge line of 70 µm or less as a result of preventing chipping from affecting cutting accuracy such as cutting or punching. Becomes possible. The smaller the maximum height Rmax is, the smaller the chipping is suppressed. In this case, as the value of B increases, Rmax can be further reduced. For example, a more desirable value of Rmax of 50 μm or less, and a more desirable value of 30 μm or less can be realized.

Next, the above-mentioned alumina-based ceramic material can be a composite ceramic material containing a zirconia-based ceramic phase in a range of 20% by volume or less. As a result, the fracture toughness value of the alumina-based ceramic material, as well as the chipping resistance and wear resistance, are significantly improved, and the life of the edged ceramic member made of the alumina-based ceramic material can be greatly improved.

Z which is a main component of the zirconia ceramic phase
It is known that rO ₂ and HfO ₂ undergo a transformation between three types of phases having different crystal structures with a change in temperature. Specifically, a monoclinic phase at a low temperature side including room temperature, On the higher temperature side, it becomes a tetragonal phase, and on the higher temperature side, it becomes a cubic phase. When the entire zirconia-based ceramic phase is composed of at least one of ZrO ₂ and HfO ₂ ,
Near room temperature, it is considered that almost all of the phase becomes a monoclinic phase. However, ZrO ₂ and HfO ₂
As a stabilizing component, a certain amount or more of an oxide of an alkaline earth metal or a rare earth metal oxide (such as calcia (CaO) or yttria (Y ₂ O ₃ )) is dissolved to form a monoclinic system. It is known that the transformation temperature between the phase and the tetragonal phase decreases, and the tetragonal phase can be stabilized in a temperature range near room temperature.

Here, it is known that the phase transformation from the tetragonal phase to the monoclinic phase is based on a so-called martensitic transformation mechanism or a similar phase transformation mechanism. When stress is applied, the transformation temperature rises and the tetragonal phase undergoes stress-induced transformation, and the strain energy due to the stress is consumed as a driving force for the transformation, so that the added stress is relaxed. Becomes Therefore, in such a ceramic structure in which the zirconia-based ceramic phase particles containing a tetragonal phase are dispersed, if chipping is to occur during mechanical polishing for forming a sharp edge portion, the above-mentioned near the crack tip is considered. When the zirconia-based ceramic phase particles are present, the tetragonal phase is transformed into a monoclinic phase due to stress concentrated at the crack tip. As a result, the stress concentration on the crack tip is alleviated, and the propagation of the crack is prevented or alleviated.

In other ceramic materials that do not exhibit stress relaxation due to transformation, the fracture energy is thought to act exclusively in the direction of expanding the crack by elastic energy, whereas in the case of a composite ceramic material in which a zirconia-based ceramic phase is dispersed, It is considered that the volume expansion of the transformation region formed at the crack tip applies compressive stress to the wake region adjacent to the crack opening side, and this acts in the direction to close the crack to suppress crack propagation. As described above, the mechanism of accumulating strain energy due to crack propagation is significantly different between the above-described composite ceramic material and other ceramics.

When the content of the zirconia ceramic phase is 20
If the content is more than% by volume, the above-described effect of improving the performance due to the blending of the zirconia-based ceramic phase is reduced, and the cost is increased by the increase in the content of the expensive zirconia-based ceramic. Also,
When used for cutting tools, etc., heat removal of the material is important, and it can be said that the use of alumina-based ceramics having high thermal conductivity is advantageous in this respect, but the content of the zirconia-based ceramic phase is reduced. If it exceeds 20% by volume, the heat transfer rate of the material may be impaired and the cutting performance may be adversely affected. On the other hand, when the content of the zirconia-based ceramic phase is less than 1.5 volumes, the above-described effect of improving the performance by the zirconia-based ceramic phase may not be sufficiently expected. More preferably, the content of the zirconia-based ceramic phase is 3 to 15% by volume.

Further, it is desirable that the relative density of the alumina ceramic material is 98% or more. Relative density is 98
% Or less, depending on the purpose of use of the ceramic member with an edge (for example, when a strong frictional force or impact force is applied such as a cutting tool or a punching tool and a very sharp edge portion is required, etc.). Even when the value is 3.5 or more, sufficient bending strength cannot be obtained, and it may be impossible to use.

As the stabilizing component of the zirconia-based ceramic phase, one or more of Ca, Y, Ce and Mg are used. Ca is CaO, Y is Y ₂ O ₃ , and Ce is Ce.
The O _2, Mg is at value converted respectively oxide MgO, a total content of the zirconia ceramic phase are desirably contained at 1.4 to 4 mole percent range. When the content of the stabilizing component is less than 1.4 mol, the content ratio of the monoclinic system phase increases, and as a result, the content ratio of the tetragonal system phase relatively decreases, and the above-mentioned stress relaxation effect is sufficiently improved. In some cases, chipping resistance when forming a sharp edge portion under the above conditions is insufficient. On the other hand, when the content of the stabilizing component exceeds 4 mol%, the content ratio of the cubic phase increases, and similarly, the chipping resistance may be insufficient. The content of the stabilizing component is more desirably 1.5 to
The content is preferably 4 mol%, more preferably 2 to 4 mol%.

As a stabilizing component of the tetragonal phase, specifically, Y ₂ O ₃ has higher strength of the obtained ceramic material as compared with the case where other stabilizing components are used. Since they are relatively inexpensive, they are suitably used in the present invention. On the other hand, CaO and MgO are not as strong as those using Y ₂ O ₃ , but the strength of the obtained ceramic material is relatively high and it is even cheaper than Y ₂ O _3. It is preferably used. Note that Y
₂ O ₃ , CaO and MgO may be used alone or in combination of two or more.

The main component of the zirconia-based ceramic phase
(Not limited to this, the term “principal component” in this specification refers to the most important component.
ZrO which means a component having a high content ratio)₂as well as
HfO₂Are similar in chemical and physical properties,
Use either alone or in combination of both
Anything is possible. However, ZrO ₂
Is HfO₂Zirconia because it is cheaper than
The ceramic phase is ZrO₂Can be composed mainly of
It is more desirable. In addition, usually supplied
Pure ZrO₂The raw material is a trace amount of HfO₂Is contained
However, when using such raw materials,
HfO contained for the reasons described above₂Actively
Very little need to be removed.

The zirconia ceramic phase preferably has a ratio CW / TW of the existing weight CW of the cubic phase to the existing weight TW of the tetragonal phase of less than 1. The cubic phase is easily formed when the content of the above-mentioned stabilizing component increases and the transformation point between the phase and the tetragonal phase decreases, or when the firing temperature exceeds 1600 ° C. Compared with a crystalline phase or a tetragonal phase, it has a property that crystal grains are likely to become coarse during firing. Then, the coarsened crystal grains of the tetragonal phase are likely to be shed due to a small interfacial bonding force with other crystal grains, and when the amount of the tetragonal phase increases until the above ratio exceeds 1, The formation amount of such coarse crystal grains also increases. In any case, the chipping resistance at the time of forming the sharp edge portion under the above conditions is impaired. Therefore, the ratio CW / TW should be less than 1, preferably less than 0.5, and more preferably less than 0.5.
It is better to be less than 1.

The information on the abundance ratio between the tetragonal phase and the cubic phase is obtained as follows. For example, a part of a ceramic material is mirror-polished, and X-ray diffraction is performed on the polished surface by a diffractometer method. In this case, in the obtained diffraction pattern, the (111) intensity peak positions, which are the main diffraction peaks of the tetragonal phase and the cubic phase, appear close to each other. And (11-1) the sum of the intensity Im and the (111) intensity of the tetragonal phase and the cubic phase It + Ic
From the ratio, the abundance of the monoclinic phase is determined. Next, the sintered body is mechanically pulverized and subjected to X-ray diffraction again to determine the (111) intensities I ′m and I′c of the monoclinic phase and the cubic phase. In this case, due to the mechanical stress associated with the grinding,
Since it is considered that the tetragonal phase of the sintered body is transformed into a monoclinic phase, the abundance of the cubic phase can be determined from I′c / (I ′m + I′c). The I'c /
The value of (I'm + I'c) is 0.5 or less, preferably 0.1
The following conditions are desirable in order to improve chipping resistance when forming a sharp edge portion under the above conditions.

Next, the alumina-based ceramic material is a composite ceramic material containing a conductive inorganic compound phase in which the metal cation component is at least one of Ti, Zr, Nb, Ta and W in a range of 60% by volume or less. It can be. By being contained in the conductive inorganic compound phase,
Conductivity can be imparted to the alumina-based ceramic material, and the ceramic material can be subjected to electric discharge machining such as wire cutting. The conductive inorganic compound is
It can be at least one of metal nitride, metal carbide, metal boride, metal carbonitride, and tungsten carbide containing at least one of Ti, Zr, Nb, and Ta as a metal cation component. Titanium nitride,
Examples thereof include titanium carbide, titanium boride, tungsten carbide, zirconium nitride, titanium carbonitride, and niobium carbide. If the content of the conductive inorganic compound phase is less than 20% by volume, the effect of improving the conductivity of the material may be insufficient. On the other hand, when the content of the conductive inorganic compound phase exceeds 60% by volume, the strength and fracture toughness of the composite ceramic material are impaired, and a material satisfying the above condition (1) cannot be obtained. On the other hand, the thermal conductivity of the alumina-based ceramic material may be impaired.

The ceramic member with an edge as described above can be applied to a cutting tool using the sharp edge portion as a cutting edge. In addition, for the shearing process using the sharp edge portion as a working portion of the processing force, for cutting,
The present invention can also be applied to a ceramic processing tool for bending or deep drawing. In the ceramic member with an edge of the present invention, a sharp edge portion with few defects caused by chipping is formed, and this is used as a cutting edge of a cutting tool or a working portion of a processing force of the above-mentioned ceramic processing tool. Thus, highly accurate processing can be performed.

Next, the first of the manufacturing methods of the ceramic member with an edge according to the present invention is that it is made of an alumina-based ceramic material containing 20% by volume or more of an alumina-based phase and has an average particle diameter d (unit: μm), the fracture toughness value is K
When C (unit: MPa · m ^1/2 ), −0.2
Using an exponential value A which is set in a range of 7~-0.20, KC / by performing polishing on the outer surface of ^{(d A)} of alumina-based ceramic materials satisfying ≧ 3.5, 2 one edge An edge portion that appears in a ridgeline shape at the intersection of the forming surfaces, and the width of the edge tip portion that appears at the cut when cut along an arbitrary plane orthogonal to the ridgeline direction is 0.3 mm or less, and the ridgeline direction Height Rmax of edge tip surface roughness measured at 70 μm
The following sharp edge portion is formed.

If the values of K C and d of the alumina-based ceramic material are adjusted so that B≡K C / (d ^A ) ≧ 3.5, the width of the edge end portion is 0.3 m by polishing.
m, the maximum height Rmax of the edge tip surface roughness can be set to 50 μm or less even if a sharp edge portion of less than m is formed. That is, a sharp edge portion with little chipping can be formed.

The second method of the present invention for producing a ceramic member with an edge is to polish the outer surface of an alumina-based ceramic material containing 20% by volume or more of an alumina-based phase to form an outer surface of the two edge-formed surfaces. In a method for manufacturing an edged ceramic member by forming one or more edges that appear in a ridge line shape at the intersection position, prior to polishing, an average particle diameter d (unit: μm) of the alumina-based ceramic material prior to polishing. And the fracture toughness value KC (unit: MPa ·
m ^1/2 ), and their d and K C are -0.2
Using an exponential value A which is set in the range of 7 to-0.20, so that applying only grinding the alumina-based ceramic material satisfying ^{KC / (d A) ≧ 3.5} .

Prior to polishing, Kc and d of the alumina-based ceramic material are measured, and based on the measured values,
By checking whether or not B≡KC / (d ^A ) ≧ 3.5, it is possible to determine whether or not the material is likely to cause chipping before polishing. As a result, it is possible to determine whether or not the material is suitable for forming a sharp edge portion without actually performing polishing, so that, for example, during mass production, processing is performed on an originally inappropriate material. Waste material can be eliminated, and if the material is in the development stage, it greatly contributes to shortening the material development time or development cost.

The alumina-based ceramic material can be manufactured, for example, as follows. First, a raw material in which the above-mentioned zirconia-based ceramic phase particles or conductive inorganic compound phase particles are blended as the second phase particles with alumina powder or alumina powder, if necessary, reacts with a raw material such as water or ethanol. (A difficult organic solvent) to form a slurry. Although the mixing method is not particularly limited, for example, ball mill mixing, trommel mixing, attrition mill mixing and the like can be employed. At this time, if necessary, various additives, for example, a dispersant or deflocculant such as ammonium polycarboxylate, a binder such as polyvinyl alcohol or polyacrylate emulsion, stearic acid or microwax or A plasticizer such as paraffin may be added at the same time. Further, an antistatic agent, an antifoaming agent and the like can be added simultaneously.

The slurry thus obtained is dried and granulated by an appropriate method to form a dry granulated powder. As the dry granulation method, a spray drying method (spray drying method), a freeze drying method, a reduced pressure drying method, or the like can be employed. this house,
In the spray drying method, Ti,
When using at least one of metal nitride, metal carbide, metal boride and metal carbonitride containing at least one of Zr, Nb and Ta as a metal cation component and tungsten carbide, spray drying is used. In order to prevent or suppress the oxidation of the raw material, it is desirable to set the inlet temperature of the hot air used for the heating to 200 ° C. or lower, preferably 170 ° C. or lower.

The dry granulated powder thus obtained is formed into a desired ceramic member shape. As the molding method, a mold press, a cold isostatic press, a slurry casting (slip casting), an extrusion molding, an injection molding, or the like can be employed. It is also possible to combine some of the above methods, such as performing a mold press at low pressure followed by a cold isostatic press.

The obtained molded body is fired by an appropriate method to form a sintered body. As the firing method, a normal pressure sintering method, a hot pressing method, a hot isostatic pressing (HIP) method, or the like can be adopted. It is also possible to combine some of the above methods, such as performing a hot isostatic press after firing by the normal pressure sintering method. When the conductive inorganic compound phase particles are contained, it is preferable to use an oxidizing atmosphere such as an air atmosphere, and when the conductive inorganic compound phase particles are contained, the firing atmosphere is an inert atmosphere (vacuum atmosphere). ) Or a reducing atmosphere such as a hydrogen atmosphere. The firing temperature is from 1200 to 1
The temperature can be set at 900 ° C., preferably in the range of 1300 to 1800 ° C. When the molded product contains an organic additive (for example, the above-described dispersant, deflocculant, binder, lubricant, antistatic agent, antifoaming agent, etc.), firing in the above temperature range is performed. Prior to this, it is desirable to calcine at 400 to 600 ° C. to remove or reduce the organic additive component by decomposition or evaporation in advance.

When the above-mentioned conductive inorganic compound phase particles are blended, metallic titanium is used as an oxygen getter to suppress oxidation of the conductive inorganic compound phase particles during firing.
It is desirable to contain it in the range of about to 10% by volume. Thereby, the strength, fracture toughness value, or electrical conductivity of the finally obtained composite ceramic material can be improved. In this case, the obtained composite ceramic material contains a Ti element component present in the form of titanium metal and / or titanium oxide in a range of 5 to 10% by volume.

The outer surface of the ceramic sintered body thus obtained is polished to form a sharp edge. In this case, for example, both of the two edge forming surfaces are polished with a grindstone to finish the sharp edge portion having the above-mentioned edge tip width. For example, in the case of using a rotary grindstone, the number 200 to 8 specified in JISB4130 is used.
It is preferable to use a diamond grindstone of No. 00, and to make the rotation direction coincide with the ridge direction of the edge portion to be formed and the feeding direction of the work (ceramic sintered body).
It is desirable to further suppress the occurrence of chipping. Also,
The rotational peripheral speed is 1000 to 6000 m / min, the cutting amount per pass is 0.5 to 5 μm, and the workpiece feed speed is 1
It is desirable to set it to 20 m / min.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to embodiments shown in the drawings. First, a cutting tool as an example of the member with an edge of the present invention will be described. The cutting tool 1 shown in FIG. 2 is CCMT060204E according to the ISO standard.
It has a shape defined as N. That is, the tool 1 has, for example, a flat prismatic shape having a substantially parallelogram cross section with a thickness S of about 2.38 mm and a diameter of an inscribed circle CI of about 6.35 mm (the corner angle of the main surface is, for example, 10 mm).
0 ° and 80 °), and the size rε of the radius applied to each corner is about 0.4 mm. The one main surface 1c is a rake face 1c ', and the outer peripheral edge is a cutting edge 1k, which is finished as a sharp edge portion in the present invention.

FIG. 3 shows an example in which the above-mentioned tool 1 is used as an outer peripheral cutting tool. As shown in FIG. 3A, the bar-shaped workpiece W is rotated around the axis, and the tool 1 is brought into contact with the outer peripheral surface thereof as shown in FIG.
By using the c ′ and the side surface 1e (FIG. 2) as the flank, the outer peripheral surface of the workpiece W can be continuously cut. Note that 1 g indicates a lateral flank and 1 f indicates a front flank.

The tool 1 is made of an alumina ceramic material. This alumina-based ceramic material contains an alumina-based phase in a range of 20% by volume or more. For example, the average particle diameter is d (unit: μm), and the fracture toughness value is KC.
(Unit: MPa · m ^1/2 ), -0.27
^A material having a relative density of 98% or more that satisfies Kc / (dA) ≧ 3.5 using an index value A set in a range of −0.20. For this purpose, a zirconia-based ceramic phase containing 50% by weight or more of zirconium oxide as needed is 20% by volume or less, or 60% by volume of the conductive inorganic material particles of the above-mentioned material.
It is blended in the following range. Then, as shown in FIG. 4, the above-mentioned sharp edge portion E has a width w of 0.3 mm or less at the edge tip portion that appears at the cut when cut along an arbitrary plane AP orthogonal to the ridge line direction, and The maximum height Rmax of the edge tip surface roughness measured by moving the roughness measuring probe PQ in the ridge direction is 50 μm or less. By performing cutting using such a sharp edge portion E, the outer peripheral surface of the workpiece W can be accurately finished.

In the edged ceramic member of the present invention, the outer edge position of the edge tip width w may be unclear depending on the cross-sectional shape of the edge tip. In this case, the edge tip width w is determined as shown in FIG. First, on the plane AP (FIG. 4), the center line O is set at a position where the angle θ between the two cut lines P1 and P2 representing the edge forming surface is bisected (the undulation of the cut lines P1 and P2). Is relatively large, an integration center line with an average surface roughness is used.) Next, from the edge tip position T in the direction of the center line O, 0.3
A reference line B orthogonal to the center line O is set at a position of mm. Further, each intersection point between the reference line B and the cut lines P1 and P2 is X and Y, and the distance of XY is L, and 0.01 L inside each of X and Y (1% position of the length of L). At the position
The points X 'and Y' are set. Then, a straight line P1 'parallel to P1 through X' and a straight line P1 parallel to P2 through Y '
2 ′, and X ″ −Y ″ in the direction of the reference line B, assuming that the intersection point between this and the edge tip surface is X ″, Y ″.
The distance between them is defined as the edge tip width w.

When the edged ceramic member is used as a tool, as shown in FIG. 5B, a surface called a chamfer is provided adjacent to the rake face 1c side of the cutting edge (sharp edge). There may be a case where a cut portion CT is formed. This makes it difficult for chipping of the cutting edge to occur during cutting use (this has a different meaning from chipping that occurs at the time of forming an edge when manufacturing a tool). In this case, a sharp edge portion including the chamfered portion CT is regarded as a sharp edge portion. It can be effectively prevented.

Further, the conductive inorganic material particles are contained at a volume content of 2%.
If the alumina-based ceramic material blended in the range of 0 to 60% by volume is used, the general shape of the cutting tool 1 shown in FIG. 2 can be cut out by electric discharge machining. Then, a sharp edge portion E can be formed by polishing the side surface 1e (1g, 1f) serving as the flank surface using a diamond grindstone or the like.

FIG. 6 shows an example of a ceramic mold to which the present invention is applied. In this embodiment, the mold is referred to as a "mold". However, the mold is actually made entirely of an alumina-based ceramic material and is not made of metal. The die includes a punching die 6 and a punching punch 4 that enters and exits the die hole 7. In this embodiment, the punching die 6 has a sharp edge E at the opening edge of the die hole 7. It is constituted as a ceramic member with an edge of the present invention. In the punching die 6, only the peripheral portion of the die hole including the sharp edge portion E may be formed of alumina-based ceramic, and the remaining portion may be formed of a metal material or another ceramic material. Note that the punch 4 for punching has a punch tip surface 5 corresponding to an opening to be punched out of a metal plate member. Naturally, the punch 4 for punching can also be constituted as the ceramic member with an edge of the present invention in which a sharp edge portion E is formed at the intersection of the punch outer peripheral surface 8 and the punch tip surface 5. .

Further, the ceramic member with an edge of the present invention can be applied to a die 71 for deep drawing as shown in FIG. Here, the inner peripheral edge of the die hole 71 is a sharp edge portion E. Further, the deep drawing punch 70 can also be configured as the ceramic member with an edge of the present invention, in which the peripheral edge of the punch tip surface is a sharp edge portion E.

[0042]

[Experimental example] For alumina raw materials with various average particle sizes (Sumicorundum series manufactured by Sumitomo Chemical Co., Ltd.)
A commercially available partially stabilized zirconia raw material having a Y ₂ O ₃ content of 2 mol%, 3 mol%, and 4 mol% (OZC series manufactured by Sumitomo Osaka Cement Co., Ltd.), or one or two of Ti, Zr, Nb, and Ta A second phase particle material comprising at least one of a metal nitride, a metal carbide, a metal boride and a metal carbonitride having at least one kind as a metal cation component, and tungsten carbide so as to have a composition shown in Table 1. After being compounded and formed by a die press, a hot isostatic press (HI
P) or hot press under various conditions. In the former, the primary baking was performed in a nitrogen atmosphere of 2 atm for 1 hour.
After performing at various temperatures of 300 to 1850 ° C. for 2 hours, HI
P treatment was performed under argon atmosphere at 1500 atm.
Performed at various temperatures of １1700 ° C. for 2 hours. The latter was carried out at a pressure of 200 kg / cm ² at various temperatures of 1600 to 1900 ° C. for 2 hours in an argon atmosphere (preliminary firing and the like were not performed).

The average particle size of each of the obtained sintered bodies was 1300 ° C. after the material surface was mirror-polished by surface grinding and lapping.
Was subjected to SEM observation (magnification: 5000 times) by thermal etching in a nitrogen atmosphere at normal pressure, and measurement was performed on the observed image by the method described above based on the Schwarts-Saltykov method.
Further, the fracture toughness value is defined by S defined in JIS: R1607.
It was measured by the EPB method.

The above sintered body was processed into a rectangular parallelepiped test piece of 20 × 10 × 60 mm by polishing using a surface grinder (PFG-450DXA manufactured by Okamoto Machine Tool Works, Ltd.). In addition, the kind of the grindstone used and the grinding processing conditions are as follows: Using a diamond grindstone having a diameter of 180 mm, a thickness of 10 mm, and a count of 400 (SDC400-J100-BN-5.0 manufactured by Toyota Ban Mopps) specified in JIS B 4131. , Peripheral speed 1400m / min, table feed speed 5m / min,
Mechanical polishing is performed in the edge forming direction with a depth of cut of 5 μm per pass.

Next, a shape measurement for measuring an edge tip width w and a surface roughness measurement in a ridge direction were performed on each edge portion of the test piece. The shape measurement was performed using a shape measuring machine (CONTRACER CPH-400, manufactured by Mitutoyo Corporation). Each edge was observed with an optical microscope (magnification: 50 times). One or more chippings having a width or depth of 0.1 mm or more were not recognized (x), and 0.05 mm or more and 0.1 mm or more were not observed. If one or more chippings of less than 1 mm are recognized at one or more places (△), 0.02
The chip was evaluated as good (○) when chipping of 1 mm or more and less than 0.05 mm was recognized at one or more places, and evaluated as excellent (●) when chipping of 0.02 mm or more was not recognized at all.

Further, for each sintered body containing a zirconia-based phase, the abundance ratio between the tetragonal phase and the cubic phase was determined as follows. That is, a part of the sintered body is mirror-polished, and X-ray diffraction is performed on the polished surface by a diffractometer method. First, (1) of the monoclinic phase
From the ratio of the total strength Im of 11) and (11-1) to the sum of the (111) strengths of the tetragonal phase and the cubic phase It + Ic, the weight ratio MW of the monoclinic phase and the tetragonal phase The weight ratio TW + CW of the phase + cubic phase is determined. Next, the sintered body is mechanically pulverized and subjected to X-ray diffraction again to determine the (111) intensities I ′m and I′c of the monoclinic phase and the cubic phase. It is considered that the tetragonal phase of the sintered body is completely transformed into the monoclinic phase due to the mechanical stress accompanying the pulverization.
The weight ratio CW of the cubic phase is determined from (I'm + I'c). Since TW + CW is required first, C
If W is reduced, the weight ratio TW of the tetragonal phase can be determined. The above results are shown in Tables 1 to 6.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

[0050]

[Table 4]

[0051]

[Table 5]

[0052]

[Table 6]

Next, FIG. 1 shows the measurement results of the fracture toughness value K C of each of the test pieces with respect to the results of Tables 1 to 6, plotted against the measurement results of the average particle size d. Show. As can be seen, the boundaries between the data points of “x” and “△”, the data points of “△” and “○”, and the data points of “○” and “●” Are delimited by a function curve of KC = B · d ^A type. Further, when A is in the range of -0.27 to -0.20, there is a correlation between the constant B and whether or not chipping is likely to occur when the sharp edge portion is formed. When the value is 3.5 or more, “○” is added, and then 4.5
In the above, it is also understood that the result is sequentially better as "●". In addition, when CW / TW is less than 1, it can be seen that chipping resistance is particularly good.

[Brief description of the drawings]

FIG. 1 is a graph in which the measured values of the fracture toughness values are plotted against the measured values of the average grain size in the data of each material in the experimental examples.

FIG. 2 is a view showing a cutting tool as an embodiment of the ceramic member with an edge according to the present invention.

FIG. 3 is an explanatory view showing a method of using the cutting tool of FIG. 2;

FIG. 4 is an explanatory diagram of a sharp edge portion.

FIG. 5 is an explanatory diagram showing a definition of an edge tip width.

FIG. 6 is a perspective view showing an example of a punching die and a punching die as an embodiment of the ceramic member with an edge according to the present invention.

FIG. 7 is a schematic view showing an example in which a punch and / or a die for deep drawing is used as a ceramic member with an edge according to the present invention.

[Explanation of symbols]

Reference Signs List 1 cutting tool (ceramic member with edge) E sharp edge portion 4 punching punch (ceramic member with edge) 6 punching die (ceramic member with edge) 7 die hole 70 punch for deep drawing (ceramic member with edge) 71 deep Die for drawing (ceramic member with edge)

Claims (10)

[Claims] 1. An alumina-based ceramic material containing 20% by volume or more of an alumina-based phase, having an average particle size of d (unit: μm) and a fracture toughness value of KC
(Unit: MPa · m ^1/2 ), -0.27
Using an exponential value A set in the range of ~-0.20, is intended to satisfy the ^{KC / (d A) ≧ 3.5} , and the member outer surface, the intersection of two edges forming surface One or more edges that appear in a ridge shape at the position are formed, and at least one of the edges is the edge tip portion that appears in the cut when cut along any plane perpendicular to the ridge direction. An edged ceramic member having a width of 0.3 mm or less and formed as a sharp edge portion. 2. The sharp edge portion has a maximum height Rmax of an edge tip surface roughness measured in the ridge direction of 70 μm.
The edged ceramic member according to claim 1, wherein: 3. The ceramic member with an edge according to claim 1, wherein the alumina-based ceramic material is a composite ceramic material containing a zirconia-based ceramic phase in a range of 20% by volume or less. 4. As a stabilizing component of the zirconia-based ceramic phase, one or more of Ca, Y, Ce and Mg, Ca is CaO, Y is Y ₂ O ₃ , and Ce is CeO
₂ , Mg is a value converted to oxides of MgO.
The content in the zirconia-based ceramic phase is 1.
The edged ceramic member according to claim 3, which is contained in a range of 4 to 4 mol%. 5. The zirconia-based ceramic phase according to claim 3, wherein the ratio CW / TW of the cubic phase existing weight CW to the tetragonal phase existing weight TW is less than 1. Ceramic members. 6. The composite ceramic material, wherein the alumina-based ceramic material contains a conductive inorganic compound phase in which a metal cation component is at least one of Ti, Zr, Nb, Ta, and W in a range of 60% by volume or less. The edged ceramic member according to any one of claims 1 to 5, wherein 7. The conductive inorganic compound is Ti, Zr,
The ceramic member with an edge according to claim 6, wherein the ceramic member is at least one of a metal nitride, a metal carbide, a metal boride, a metal carbonitride, and tungsten carbide containing at least one of Nb and Ta as a metal cation component. 8. The ceramic member with an edge according to claim 6, wherein a Ti element component present in the form of titanium metal and / or titanium oxide is contained in a range of 10% by volume or less. 9. The ceramic member with an edge according to claim 1, wherein the ceramic member with an edge is a cutting tool using the sharp edge portion as a cutting edge. 10. A ceramic working tool for shearing, cutting, bending, or deep drawing using the sharp edge portion as a working portion of a working force, wherein the edged ceramic member is used. 9. The ceramic member with an edge according to any one of items 8 to 8.