JP2004043255A - Composite structure - Google Patents

Abstract

The present invention provides a composite structure that can achieve both high hardness and high toughness.
A composite structure is formed by covering the outer periphery of a long core material with a skin member having a different composition from the core material. One or more of TiC whiskers, TiN whiskers, and SiC whiskers were dispersed in an Al ₂ O ₃ matrix.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a composite structure in which an outer periphery of a long core material is covered with a skin member.
[0002]
[Prior art]
Conventionally, Al ₂ O ₃ composite ceramics are known as materials having high hardness and high strength, and are widely used as structural materials. For example, Japanese Patent Application Laid-Open No. Hei 2-229775 describes that a composite ceramic in which fine TiC particles are dispersed in Al ₂ O ₃ has an effect of suppressing crack propagation.
[0003]
[Problems to be solved by the invention]
However, the conventional composite ceramics of Al ₂ O ₃ and TiC have a problem in that the effect of suppressing crack propagation is low and, for example, when used as a cutting tool or the like, the fracture resistance is poor. In addition, TiC whiskers are difficult to manufacture due to their production, and there is a problem that the cost is high.
[0004]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a composite structure having both high hardness and high toughness.
[0005]
[Means for Solving the Problems]
As a result of studying the above problem, the present inventor has found that, in a composite structure in which the outer periphery of a long core material is covered with a skin member having a composition different from that of the core material, the core material and / or the skin member are made of Al _2. By forming a composition in which at least one of TiC whisker, TiN whisker and SiC whisker is dispersed in an O ₃ matrix, the direction of crack propagation due to the difference in properties between the core material and the skin member can be reduced. It is possible to deflect and improve the toughness of the member, and because of the whisker dispersion, the crack is deflected and the toughness of the member is improved, so that the toughness of the entire composite structure can be more efficiently improved, and high hardness and high hardness can be achieved. It has been found that the composite structure has toughness.
[0006]
The composite structure of the present invention is obtained by covering the outer periphery of a long core material with a skin member having a different composition from that of the core material, wherein the core material and / or the skin member are made of Al ₂ O. ₃ , wherein one or more of TiC whiskers, TiN whiskers and SiC whiskers are dispersed in a matrix.
[0007]
Here, at least a part of the whisker is obtained by carbonizing or nitriding a metal whisker or an oxide whisker raw material, and the content of the TiC whisker or the TiN whisker dispersed in the core material and / or the skin member is reduced. Desirably, it is 1 to 50% by volume.
[0008]
Further, the and the 90-55 wt% core material _Al 2 _{O 3,} wherein the whisker component with a proportion of 10 to 45 wt%, the _Al 2 O compositionally different from the skin member is the core ₃ and 10 to 60 wt%, by containing TiC and / or TiN at a rate of 90 to 40 wt%, and a 95 to 55% by weight said core material _Al 2 _{O 3,} the whisker component 5 It is preferable that the skin member be contained at a ratio of 45% by weight, and the skin member be made of any one of metal Co, metal Ni, cemented carbide and cermet.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The composite structure of the present invention will be described based on a schematic perspective view of FIG. 1 which is an embodiment thereof.
[0010]
According to FIG. 1, the composite structure 1 has a structure in which the outer periphery of a long core material 4 is covered with a skin member 8.
[0011]
According to the present invention, it is significant that the core material 4 and / or the skin member 8 have a composition in which at least one of TiC whiskers, TiN whiskers, and SiC whiskers are dispersed in an Al ₂ O ₃ matrix. Due to this, the difference in properties between the core material and the skin member, the effect of crack propagation due to whiskers, bridging, debonding, and pull-out effects become more pronounced, reducing the toughness of the structure without lowering the hardness of the member. A composite structure having high hardness and high toughness can be obtained.
[0012]
The whisker in the present invention is a whisker having an average ratio of the major axis / minor axis of the particles that can be observed in a SEM photograph of a longitudinal section (a section along the longitudinal direction of the core member and the skin member) of the structure is 2 or more. In addition, from the viewpoint of improving toughness, the major axis of the whisker particles is preferably 2 μm or more, particularly 3 μm or more, and more preferably 5 μm or more.
[0013]
Further, according to the present invention, it is desirable that at least a part of the whisker is obtained by carbonizing or nitriding a metal whisker or oxide whisker raw material. In addition, it is possible to efficiently reduce the residual carbon component remaining in the sintered body by reacting with the organic binder component contained in the structure in a large amount, and it is difficult to manufacture industrially like the TiC whisker and the TiN whisker, and the cost is high. The structure having high hardness and high toughness can be produced by using an inexpensive raw material such as TiO ₂ whisker without using an expensive raw material causing the above.
[0014]
Furthermore, for the purpose of improving the toughness of the core material and / or the skin member, it is desirable that the whiskers dispersed in the Al ₂ O ₃ matrix be contained at a ratio of 1 to 50% by volume, particularly 10 to 35% by volume.
[0015]
In addition, according to the present invention, the core material 4 is made of Al ₂ O _{3 in} that excellent wear resistance is exhibited by improving hardness and oxidation resistance, and that toughness is improved and fracture resistance is improved. the 90-55% by weight, in particular with 85 to 60 wt%, the TiC 10 to 45% by weight, in particular with a proportion of 15 to 40 wt%, 10 to 60 wt skin member 8 of _Al 2 _{O 3} %, Particularly 20 to 50% by weight, and 90 to 40% by weight, particularly 80 to 30% by weight of TiC. From the viewpoint of easily causing crack deflection, debonding, and bridging at the interface between the core member and the skin member, the content of Al ₂ O ₃ in the core member is determined by the content of Al ₂ O _{3 in} the skin member. More than 30% by weight.
[0016]
Further, according to another aspect of the present invention, in order to improve the strength and the fracture toughness value of the composite by using a metal component for the skin member, the core material 4 contains 95 to 55% by weight of Al ₂ O ₃ , In particular, 90 to 60% by weight and a whisker component are contained at a ratio of 5 to 45% by weight, particularly 15 to 40% by weight, and the skin member 8 is made of any one of metal Co, metal Ni, cemented carbide and cermet, In particular, it is desirable to be made of cemented carbide or cermet.
[0017]
In the Al ₂ O ₃ matrix, as auxiliary components, rare earth oxides, oxides of 4a, 5a, and 6a, cobalt oxide, nickel oxide, yttrium oxide, magnesium oxide, and silicon oxide were 0.1 to 10% by weight. % Is desirable for enhancing the sinterability of the member and achieving high hardness and high toughness.
[0018]
Further, in order to suppress the crack propagation of the composite structure 1, for example, the average diameter of the core material 4 is 5 to 500 μm or less, particularly 5 to 300 μm, and the average thickness of the skin member 8 is 500 μm or less, particularly 0.1 to 500 μm. It is desirable that the composite structure 1 has a diameter of 0.01 to 5 mm. However, in order to achieve both high hardness and high toughness, the average diameter D _{1 of the} core material 4 is preferable. the ratio _D 2 / _{D 1} between the average thickness _{D 2} of the skin member is 0.01 to 0.5, and is preferably 0.02 to 0.2.
[0019]
Further, FIG. 1 shows a case in which one core member 4, that is, a single body is covered with a skin member 8. However, the present invention is not limited to this, and as shown in FIG. For example, a multifilament structure in which one or more structures 1 are converged into a plurality of four or more may be used.
[0020]
Further, as shown in FIG. 2, the composite structure 1 can be formed into a sheet by arranging long ones in a predetermined length and arranging them in parallel. (B) a method of laminating the composite structures 1 so that the respective layers face in the same direction, (b) a method of laminating the elongated composite structures 1 so as to be orthogonal (intersection angle 90 °) between the layers, and (c). It is possible to produce an aligned structure by a method in which the long composite structure 1 intersects and laminates at a predetermined angle, for example, 45 °, between the layers, and anisotropic depending on the application. Of different degrees.
[0021]
On the other hand, the composite structure 1 may have a predetermined length of, for example, 0.01 to 10 mm, and may have a structure in which the structures are entangled with each other at random. According to such a structure, anisotropic properties such as hardness and toughness are obtained. A structure having uniform characteristics without generating properties.
[0022]
Next, an example of a method for manufacturing the composite structure 1 of the present invention will be described based on the schematic diagram of FIG.
[0023]
First, for example, 90 to 55% by weight of Al ₂ O ₃ powder having an average particle size of 0.1 to ₃ μm, 10 to 20% by weight of TiC powder having an average particle size of 0.5 to 5 μm, and 0.3 to 0% 0.8 μm, 10 to 45% by weight of TiO ₂ whiskers having an average length of 10 to 30 μm, carbon powder having an average particle diameter of 2 μm if desired, and optionally 0.1 to 10% by weight of the total amount of the above auxiliary component powders After mixing and kneading, an organic binder such as paraffin wax, polystyrene, polyethylene, ethylene-ethyl acrylate, ethylene-vinyl acetate, polybutyl methacrylate, polyethylene glycol, dibutyl phthalate, etc. is added and kneaded, followed by press molding. Then, a columnar molded body 12 is prepared for a core material by a molding method such as extrusion molding or cast molding (step (a)).
[0024]
On the other hand, 10 to 60% by weight of Al ₂ O ₃ powder having an average particle diameter of 0.1 to 3 μm and 90 to 10% by weight of TiO ₂ whiskers having an average diameter of 0.3 to 0.8 μm and an average length of 5 to 30 μm, particularly 20 to 40% by weight, optionally 80 to 40% by weight of TiC powder having an average particle size of 0.5 to 5 μm, carbon powder having an average particle size of 2 μm, and, if desired, a total amount of the auxiliary component powder described above. 1 to 45% by weight are added and mixed, and the above-mentioned binder and the like are added and kneaded, and two half-cylindrical skins are formed by a molding method such as press molding, extrusion molding or cast molding. A molded body 13 for a member is produced, and a composite molded body in which the molded body 13 for a skin member is arranged so as to cover the outer periphery of the molded body 12 for a core material is produced (step (a)).
[0025]
Then, the composite molded body is co-extruded to form a composite molded body 15 having a small diameter and a skin member 13 coated around the core material 12 (step (b)). Further, in order to produce a structure having a multifilament structure, a plurality of the coextruded long shaped bodies 15 may be converged and co-extruded again (step (c)).
[0026]
Further, the elongated elongated molded body 15 can be formed into a polygonal shape such as a cylinder, a triangular prism, a quadrangular prism, or a hexagonal prism, if desired. Further, the elongated molded bodies 15 may be arranged to form a sheet, and the sheets may be laminated so as to be parallel, orthogonal, or at a predetermined angle such as 45 °. Further, it is also possible to mold into an arbitrary shape by a known molding method such as a rapid proto diving method. Further, the aligned sheet or a composite structure sheet obtained by slicing the sheet in a cross-sectional direction can be bonded or bonded to the surface of a conventional hard alloy sintered body (lumps) such as a cemented carbide. is there.
[0027]
According to the present invention, in addition to the above-described method, a fibrous core material molded body is first prepared and dipped (immersed and pulled up) in a slurry for a skin member as described above. It is also possible to produce a composite structure molded body.
[0028]
Then, after the above-mentioned molded body is subjected to binder removal treatment, it is heat-treated at 1000 to 1400 ° C., particularly 1100 to 1400 ° C. for 2 hours in a vacuum or nitrogen gas atmosphere to convert the whisker into a TiC whisker or a TiN whisker. The composite structure 1 of the present invention can be manufactured by firing at 1400 to 2000 ° C., particularly 1400 to 1800 ° C. in a gas atmosphere such as Ar gas. In firing, if desired, HIP firing may be performed at 1000 to 1900 ° C, particularly 1300 to 1700 ° C.
[0029]
Further, with respect to the obtained structure 1, a carbide, nitride, carbonitride, or the like of a metal of Group 4a, 5a, or 6a of the periodic table is formed on the surface of the structure by a thin film forming method such as a CVD method or a PVD method. It is also possible to form a film.
[0030]
【Example】
(Example 1)
80% by weight of Al ₂ O ₃ powder having an average particle diameter of 0.3 μm, 19% by weight of TiO ₂ whiskers having an average diameter of 0.5 μm and an average length of 15 μm in terms of TiN, and Y ₂ O ₃ powder having an average particle diameter of 1 μm 1% by weight, and an organic binder and a solvent were added thereto, and the kneaded mixture was kneaded into an extruder and extruded into a fiber having a diameter of 500 μm to obtain a molded body for a core material.
[0031]
On the other hand, 20% by weight of Al ₂ O ₃ powder having an average particle diameter of 1 μm, 58% by weight of TiC powder having an average particle diameter of 1 μm, 20% by weight of SiC whiskers having an average diameter of 0.5 μm and an average length of 15 μm, 1 μm of Y ₂ O ₃ powder (2% by weight) is weighed, and an organic binder and a solvent are added thereto and mixed to form a slurry. The fibrous core material compact is immersed in the slurry and pulled up to obtain a core. A 15 μm-thick skin member was coated on the outer periphery of the material molding, and dried in air for 24 hours to produce a composite structure.
[0032]
After that, the composite structure was cut at intervals of 50 mm, a plurality of sheets were arranged in parallel, a plurality of sheets were prepared, and a laminate was formed so that the composite structures between the sheets became 45 °, and cut into a predetermined shape. did. Then, the laminate is subjected to a binder removal treatment at 600 ° C. for 5 hours, and heat-treated at 1300 ° C. for 2 hours in a nitrogen atmosphere at 1 atm to change TiO ₂ whiskers to TiN whiskers. It was applied and hot pressed. In the obtained composite structure, the average diameter of the core material was 400 μm, and the thickness of the skin member was 10 μm.
[0033]
Further, the sintered body was cut into a cutting tool shape of SNGN120420, and the state of the cutting edge after cutting 8000 m under the following conditions was observed with a microscope. As a result, no chipping occurred due to nose wear of 0.14 mm.
(Cutting conditions)
Work material FCD450
Cutting speed 400m / min
Feeding 0.4 mm / rev.
Cut 2mm
Dry cutting (Example 2)
Added to the average particle _Al 2 _{O 3} powder 90 wt% of the diameter 2 [mu] m and TiC powder 8% by weight, was added to _Co 3 _{O 4} powder having an average particle size of 2 [mu] m 2 wt%, this organic binder, a lubricant, kneaded After that, a molded body for a core material having a diameter of 20 mm was produced by press molding. In addition, 40 wt% of Al ₂ O ₃ powder having an average particle size of 2 μm, 25 wt% of TiC powder, 30 wt% of TiC whiskers having an average diameter of 0.5 μm and an average length of 15 μm, and a CoO powder having an average particle size of 2 μm were used. After adding ₂ % by weight, 2% by weight of Y ₂ O ₃ powder and 1% by weight of MgO, and adding and kneading a binder and a lubricant to the mixture, press molding is performed to form a 1 mm-thick half cylindrical cylindrical skin member. Two molded bodies were produced, and a composite molded body in which the periphery of the core molded body was covered was produced.
[0034]
Then, after the composite molded article was co-extruded and elongated, 100 elongated molded articles were converged and co-extruded again to produce a multi-filament type molded article. Thereafter, the molded body was subjected to a binder removal treatment, and then set in an ultra-high pressure device and fired at 1700 ° C. in an argon atmosphere at a pressure of 5 GPa to produce a composite structure. When the cross section of the structure was observed with a microscope, the diameter of the core material was 140 to 160 μm on average, and the average thickness of the skin member was 8 to 12 μm.
[0035]
The Vickers hardness (according to JISR1601) and the toughness of the sample were measured by the IF method for the obtained composite structure in the same manner as in Example 1. As a result, the hardness was 20 GPa and the fracture toughness was 9 MPa√m. As a result of evaluating the cutting characteristics under the conditions, no chipping occurred with a nose wear of 0.14 mm.
[0036]
(Comparative example)
With respect to the composite structure of Example 2, the molded body for the skin member was the same composition as in Example 2 and the same kneaded material as the molded body for the core material was used without using whiskers. A composite structure was produced in the same manner as in Example 2 except that the molded body was made of a kneaded product having the same composition and not using whiskers, and evaluated in the same manner. As a result, the hardness was 18 GPa, the fracture toughness was 4 MPa√m, A minute defect occurred at 0.25 mm.
[0037]
(Example 3)
60% by weight of Al ₂ O ₃ powder having an average particle diameter of 0.3 μm, 10% by weight of disk-shaped Al ₂ O ₃ having an average diameter of 3 μm and an average thickness of 1 μm, and 21% by weight of TiC powder having an average particle diameter of 1 μm; 5 wt% of ZrO ₂ powder having an average particle diameter of 1 μm, 1 wt% of Y ₂ O ₃ powder having an average particle diameter of 1 μm, and 2 wt% of TiO ₂ whiskers having an average diameter of 0.5 μm and an average length of 15 μm in terms of TiN. 1% by weight of MgOH having an average particle diameter of 0.5 μm in terms of MgO was weighed, an organic binder and a solvent were added thereto, and the kneaded mixture was filled into an extruder and extruded into a fiber having a diameter of 500 μm. A molded product for a core material was obtained.
[0038]
On the other hand, 100% by weight of Ni powder having an average particle diameter of 1 μm is weighed, an organic binder and a solvent are added and mixed to form a slurry, and the fibrous core material compact is immersed in the slurry and pulled up. A 5 μm-thick skin member was coated on the outer periphery of the molded body for core material, and dried in air for 24 hours to produce a composite structure.
[0039]
After that, the composite structure was cut at intervals of 50 mm, a plurality of sheets were arranged in parallel, a plurality of sheets were prepared, and a laminate was formed so that the composite structures between the sheets became 45 °, and cut into a predetermined shape. did. Then, the laminate is subjected to a binder removal treatment at 600 ° C. for 5 hours, a heat treatment is performed at 1250 ° C. for 1 hour in a nitrogen atmosphere at 1 atm, and the TiO ₂ whisker is changed to a TiN whisker. Hot press firing was performed, and then firing was performed at 1500 ° C. without applying pressure.
[0040]
In the obtained composite structure, the average diameter of the core material was 200 μm, and the thickness of the skin member was 3 μm.
[0041]
Further, the sintered body was cut into a cutting tool shape of SNGN120420, and cut under the same conditions as in Example 1 (10 km under the following conditions). As a result, no chipping occurred due to nose wear of 0.14 mm.
[0042]
(Example 4)
90% by weight of Al ₂ O ₃ powder having an average particle diameter of 0.3 μm, 5% by weight of TiC powder having an average particle diameter of 1 μm, 2% by weight of ZrO ₂ powder having an average particle diameter of 1 μm, and Y ₂ O having an average particle diameter of 1 μm ₃ 0.5% by weight of powder, 2% by weight of TiO ₂ powder having an average particle diameter of 1 μm, and 0.5% by weight of MgOH having an average particle diameter of 0.5 μm in terms of MgO, and the organic binder and solvent were weighed. Was added and kneaded to obtain a core material having a diameter of 20 mm by press molding. Further, 90.8% by weight of WC having an average particle diameter of 1 μm, 6% by weight of Co having an average particle diameter of 1 μm, 1.2% by weight of TiC powder having an average particle diameter of 1 μm, an average diameter of 0.5 μm, and an average length of 15 μm. After weighing 2% by weight of TiO ₂ whisker in terms of TiN, adding a binder and a lubricant thereto, and kneading the mixture, two molded bodies for a half-cylindrical skin member having a thickness of 1 mm were formed by press molding. A composite molded body covering the core molded body was produced.
[0043]
Then, after the composite molded article was co-extruded and elongated, 100 pieces were converged and co-extruded again to produce a multi-filament type molded article. Thereafter, the molded body is subjected to a binder removal treatment, heat-treated at 1300 ° C. for 2 hours in a nitrogen atmosphere to change the TiO ₂ whisker into a TiN whisker, and then fired without pressure at 1700 ° C. to form a composite structure. The body was made. When the cross section of the structure was observed with a microscope, the diameter of the core material was 15 to 20 μm on average, and the average thickness of the skin member was 1 to 2 μm.
[0044]
The resulting composite structure was measured for Vickers hardness (according to JISR1601) and toughness of the sample by the IF method in the same manner as in Example 1. As a result, the hardness was 19 GPa and the fracture toughness was 10 MPa√m. As a result of evaluating the cutting characteristics under the same conditions, no chipping occurred with a nose wear of 0.14 mm.
[0045]
【The invention's effect】
As described above in detail, according to the composite structure of the present invention, one or more of TiC whiskers, TiN whiskers, and SiC whiskers are dispersed in an Al ₂ O ₃ matrix in a core material and / or a skin member. By configuring with the composition of, the direction of crack propagation can be deflected due to the characteristic difference between the core material and the skin member, and the toughness of the member is improved, and the deflection of crack propagation due to whisker dispersion and the member By improving the toughness, a composite structure having both high hardness and high toughness is obtained.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing an example of a composite structure of the present invention.
FIG. 2 is a diagram showing an example in which the composite structures of FIG. 1 are combined in a flat plate shape.
FIG. 3 is a view showing an example in which the composite structure of the present invention is combined in a multifilament form.
FIG. 4 is a conceptual diagram for explaining a method of manufacturing a composite structure according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Composite structure 4 Core material 8 Skin member

Claims (5)

A composite structure in which the outer periphery of a long core material is covered with a skin member having a composition different from that of the core material, wherein the core material and / or the skin member are made of TiC in an Al ₂ O ₃ matrix. A composite structure comprising at least one of whiskers, TiN whiskers and SiC whiskers dispersed therein. The composite structure according to claim 1, wherein at least a part of the whisker is obtained by carbonizing or nitriding a metal whisker or an oxide whisker raw material. The composite structure according to claim 1, wherein the content of TiC whiskers or TiN whiskers dispersed in the core material and / or the skin member is 1 to 50% by volume. The core material contains 90 to 55% by weight of Al ₂ O ₃ and the whisker component in a ratio of 10 to 45% by weight, and the skin member contains Al ₂ O ₃ having a different composition from the core material. 2. The composite structure according to claim 1, comprising 10 to 60% by weight and 90 to 40% by weight of TiC and / or TiN. 3. The core material contains 95 to 55% by weight of Al ₂ O ₃ and the whisker component at a rate of 5 to 45% by weight, and the skin member is made of metal Co, metal Ni, cemented carbide and cermet. 2. The composite structure according to claim 1, comprising:

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