JP2005146297A - High-strength metal-matrix composite member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-strength metal-matrix composite member in which nonuniformity of mechanical properties, physical properties, etc., in the overall member is minimized. <P>SOLUTION: The metal-matrix composite member 1 consists of a ceramic formed body 2 with a three-dimensional network structure and a metal matrix 3 filled into the ceramic formed body 2. The ceramic formed body 2 has: a plurality of spherical cells 4 having uniformity in size and being in a dispersed state; and a plurality of communicating pores 6 present in a partition wall 5 between the spherical cells 4 neighboring each other. The median Md of the inside diameter of the communicating pore 6 satisfies Md≥1μm. The ratio of the median M<SB>D</SB>of the inside diameter of the spherical cell 4 to the median Md of the inside diameter of the communicating pore 6, Md/M<SB>D</SB>, is set to a value satisfying 0.1<Md/M<SB>D</SB><0.5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a high-strength metal matrix composite member.

  Conventionally, particle dispersion strengthened metal matrix composite members and fiber dispersion strengthened metal matrix composite members are known as this type of member. In the former case, there is an advantage that the directionality of strength and rigidity is small, but on the other hand, since multiple particles are in a dispersed state and the stress sharing by these particles is small, the degree of improvement in strength and rigidity by particle dispersion is small. There was a problem that was low. On the other hand, in the latter case, entanglement and line contact between fibers occur, and stress sharing by them can be obtained. Therefore, the degree of improvement in strength and rigidity is greater than that of the former. There was a problem that directionality appeared in its strength and rigidity.

Therefore, in order to alleviate the stress sharing by the reinforcing material and to relieve the direction of strength and rigidity, the ceramic molded body having a three-dimensional network structure as the reinforcing material and the metal matrix filled in the ceramic molded body are used. A metal matrix composite member has been developed (see, for example, Patent Document 1).
JP-A-6-170514

  However, the conventional ceramic molded body has a plurality of randomly arranged cells having different sizes and a plurality of communication holes existing in the partition walls between the adjacent cells. Due to non-uniform cell distribution, etc., mechanical properties such as strength, rigidity, sliding properties, etc., physical properties such as cooling performance, thermal expansion coefficient, etc. of the metal matrix composites are partially different in the parts. There was a problem of fear.

  An object of the present invention is to provide the high-strength metal matrix composite member in which nonuniformity of mechanical properties, physical characteristics, etc. in the entire member is suppressed as much as possible by improving the structure of the ceramic molded body.

In order to achieve the above object, according to the present invention, in a high-strength metal matrix composite member comprising a ceramic molded body having a three-dimensional network structure and a metal matrix filled in the ceramic molded body, the ceramic molded body comprises: It has a plurality of spherical cells that are uniform in size and in a dispersed state, and a plurality of communication holes that exist in the partition walls between adjacent spherical cells, and the median Md of the inner diameter of the communication holes is Md ≧ A metal matrix composite member having a ratio Md / M _D of 0.1 <Md / M _D <0.5, which is 1 μm, and the ratio Md / M _D of the median M _D of the inner diameter of the spherical cell to the median Md of the inner diameter of the communication hole is Provided.

  With the configuration as described above, the uniformity of the size and distribution of the spherical cells in the ceramic molded body can be improved, and the non-uniformity of the mechanical properties, physical properties, etc. of the entire member can be suppressed as much as possible. Thus, it is possible to provide a metal matrix composite member having high strength at a low volume fraction Vf. Further, this metal matrix composite member has excellent seizure resistance at a low volume fraction Vf.

  1 and 2, a high-strength metal matrix composite member 1 having a rectangular parallelepiped shape includes a ceramic molded body 2 having a three-dimensional network structure and a metal matrix 3 filled in the ceramic molded body 2. 3 and 4, the ceramic molded body 2 has a rectangular parallelepiped shape, is uniform in size, and is in a dispersed state. In the embodiment, the ceramic molded body 2 is adjacent to a plurality of spherical cells 4 arranged in a close-packed form. It has a plurality of communication holes 6 existing in the partition wall 5 between the spherical cells 4.

The median Md of the inner diameter of the communication hole 6 is set to Md ≧ 1 μm so as to allow pressure filling of the molten metal constituting the metal matrix 3. Further, in order to ensure the strength of the ceramic molded body 2, the ratio Md / M _D of the median M _D of the inner diameter of the spherical cell 4 and the median Md of the inner diameter of the communication hole 6 is 0.1 <Md / M _D <0.5. Set to However, when the ratio Md / M _D is Md / M _D <0.1, the stress concentrates on the edge of the communication hole 6 and the strength of the member 1 is reduced. On the other hand, when Md / M _D ≧ 0.5, Since the amount of 5 is reduced, the strength and rigidity of the member 1 are reduced. The median M _D of the inner diameter of the spherical cells 4 3D CT analysis, also the median Md of the inner diameter of the communication hole 6 is determined respectively by mercury porosimetry.

As a constituent material of the ceramic molded body 2, engineering ceramics such as SiC, Al ₂ O ₃ , Si ₃ N ₄ , and AlN are suitable, but are not limited thereto. Further, as the constituent material of the metal matrix 2, Al, Al alloy, Cu, Cu alloy, Mg, Mg alloy, Si, Si alloy, or the like is used.

  In manufacturing the ceramic molded body 2, as shown in FIG. 5, the following processes are used.

  (A) Step: In order to form the spherical cell 4, an aggregate of spherical synthetic resin particles 7 having a predetermined median diameter and ceramic particles 8 having a predetermined median diameter smaller than the synthetic resin particles 7 Prepare an aggregate.

  Step (b): Both aggregates are put into a coating processor to obtain an aggregate of coated particles 9 in which ceramic particles 8 are closely adhered to the surface of the synthetic resin particles 7.

  (C) Process: Putting the aggregate | assembly of the covering particle | grains 9 into a type | mold, and performing a close packing process.

  (D) Process: For example, a ceramic slurry containing ceramics of the same material as the ceramic particles 8 is injected into the mold and filled in the gaps of the aggregate.

  (E) Step: After the ceramic slurry is dried, the shaped article 11 composed of the ceramic 10 and the aggregate of the coated particles 9 is released.

  (F) Process: Heating capable of thermally decomposing the synthetic resin particles 7 in a furnace under a predetermined furnace pressure and a predetermined temperature increase rate by placing the shaped article 11 in a sintering furnace of a predetermined atmosphere The temperature is raised and the heating temperature is maintained for a predetermined time. As a result, the synthetic resin particles 7 are thermally decomposed to form the spherical cells 4 and to the partition wall forming portion 5a made of the plurality of ceramic particles 8 and ceramics 10 between the adjacent spherical cells 4. A plurality of communication holes 6 are formed by the pressure at which the gas escapes.

  (G) Process: The temperature in the furnace is raised to a temperature at which the ceramic particles 8 can be sintered, and the sintering temperature is maintained for a predetermined time. Thereby, the ceramic molded body 2 having a three-dimensional network structure is obtained.

In the manufacturing method, the inner diameter of the spherical cells 4 and the uniformization thereof depend on the median diameter of the synthetic resin particles 7, and the uniform distribution of the spherical cells 4 is performed by the closest packing process in the step (c). Achieved by: Further, the inner diameter of the communication hole 6 is controlled by the furnace atmosphere, the heating rate, the furnace pressure, the ceramic slurry viscosity (ceramic 10 concentration) and the like in the step (f). For example, combining the median diameter of the resin particles 7 is set to a predetermined value, also by controlling the rate of temperature increase, both the median Md, the ratio Md / M _D of _{M D 0.1 <Md / M D} <0 .5.

  Specific examples will be described below.

[I] Production of Ceramic Molded Body The steps (a) to (g) were performed under the conditions described below to obtain a rectangular parallelepiped ceramic molded body having a length of 20 mm, a width of 30 mm, and a length of 40 mm.

(A) Process: Aggregation of spherical synthetic resin particles: Aggregation of PMMA particles having a median diameter of 90 μm (trade name MR-90G, manufactured by Soken Chemical Co., Ltd.); Aggregation of ceramic particles: SiC having a median diameter of 0.5 μm Aggregation of particles (manufactured by Yakushima Electric Works, trade name OY-20).
(B) Process: Blending weight ratio of the aggregate of synthetic resin particles (W ₁ ) and the aggregate of ceramic particles (W ₂ ): W ₁ / W ₂ = 1/1; Coating processor: manufactured by Hosokawa Micron Name AM-15F, rotational speed 1000 rpm, processing time 0.5 h, inner piece distance 1 mm.
(C) Process: Mold dimensions and structure: Two PTFE blocks with recesses 20mm long, 30mm wide, 20mm deep are placed facing each other and have a cavity 20mm long, 30mm wide, 40mm long Close-packing treatment by vacuum filtration: A glass fiber filter medium having a 0.7 μm communicating hole is laid on the bottom of one block having a plurality of suction holes, and then inside the cavity from the opening of the other block The coated particles were introduced into the cavities, and then the inside of the cavity was depressurized through the suction holes of one block.

(D) Step: Ceramic slurry: SiC slurry (e) Step: Primary drying treatment: 20 ° C., 20 h; Secondary drying treatment: 90 ° C., 1 h.
(F) Process: furnace atmosphere: air; furnace pressure: 0.1 MPa; temperature increase rate: 10 ° C./h; heating temperature: 500 ° C., 1 h.
(G) Step: Sintering temperature: 2000 ° C .; Sintering time: 3 h.
The ceramic molded body 2 thus obtained has a three-dimensional network structure, a plurality of spherical cells 4 are arranged in a close-packed form, and the median M _D of the inner diameter is M _D = 80 μm. and the median Md of the inner diameter of the communication hole 6 is Md = 16 [mu] m, thus the ratio Md / M _D of both median Md, M _D was Md / M _D = 0.2.

[II] Manufacture of metal matrix composite member The ceramic molded body 2 was placed in the cavity of the mold, and then a molten metal of 680 ° C Al alloy (JIS ADC12) was used, injection speed 0.2m / s, casting pressure 75MPa The metal matrix composite member 1 having a length of 20 mm, a width of 30 mm, a length of 40 mm, and a volume fraction Vf of the ceramic compact 2 of Vf = 30% was obtained by performing a low-speed laminar flow die casting method. Using this member 1 as an example, 0.2% proof stress (compression) and Young's modulus were measured.

For comparison, a metal matrix composite member was manufactured in the same manner as described above using a foamed ceramic molded body manufactured by MMI having the same material and the same dimensions as the ceramic molded body. Further, a metal matrix composite member in which SiC particles having a median particle size of 15 μm were uniformly dispersed was produced. A further median M _D is M _D = 80 [mu] m inner diameter of spherical cells, also the median Md of the inner diameter of the communication hole a Md = 8 [mu] m, both median Md, the ratio Md / M _D is Md / M _D of M _D A metal matrix composite member similar to that of the example was manufactured except that = 0.1, and this was designated as Comparative Example 3. A further median M _D is M _D = 100 [mu] m inner diameter of spherical cells, also the median Md of the inner diameter of the communication hole a Md = 50 [mu] m, both median Md, the ratio Md / M _D is Md / M _D of M _D A metal matrix composite member similar to that of the example was manufactured except that = 0.5, and this was designated as Comparative Example 4. These were measured for 0.2% yield strength (compression) and Young's modulus.

  Table 1 shows various data relating to Examples and Comparative Examples 1 to 4.

From Table 1, the examples have the isotropic property to the load because the reinforcing materials are connected in a mesh form (with continuity), the distribution of spherical cells is uniform, and in addition, the median Md Since it is ≧ 1 μm and Md / M _D is 0.1 <Md / M _D <0.5, it can be seen that the strength is high. Although Comparative Example 1 has the continuity described above, the size of the spherical cells is non-uniform, so the isotropic property is moderate, and the distribution of the spherical cells is also non-uniform, so the strength is lower than that of the example. It has become. Furthermore, although the comparative example 2 is isotropic with respect to the load and the uniformity of the reinforcing material is not the continuity, the strength is lower than that of the example.

  FIG. 6 shows the relationship between the inner diameter of the spherical cell by the template method and the existence probability regarding the example and the comparative example 1. In the example, the variation range of the inner diameter of the spherical cell is 30 to 110 μm, while that of the comparative example 1 is as wide as 40 to 340 μm. Therefore, it is understood that the uniformity of the inner diameter of the spherical cell is higher in the example than in the comparative example 1.

  Next, a seizure test was performed on the examples and comparative examples 1 to 4. In the test, the test piece obtained from the example was reciprocally slid 200 times per minute with a sliding distance of 40 mm against a mating member with a CrN surface layer made of PVD. Each time 30 seconds passed, the pressing load on the test piece was increased to 9.8 N, and the load when seizure occurred, that is, the seizure occurrence load was obtained. Table 2 shows the seizure test results.

  From Table 2, it can be seen that the examples have better seizure resistance than Comparative Examples 1 to 4.

  In the metal matrix composite member, generally, means such as increasing the volume fraction Vf of the reinforcing material and improving the seizure resistance is adopted. However, as in the embodiment, the ceramic molded body having a unique structure as the reinforcing material. Can be used to have high strength and rigidity at a low volume fraction Vf and excellent seizure resistance.

  The metal matrix composite member is a cylinder block of an engine that is reinforced at one or more locations selected from around the cylinder bore, cylinder head gasket surface, bolt fastening seat surface, journal bearing, etc. In the cylinder head, the cylinder head gasket surface , Bolt tightening seat surface, cam journal bearing circumference, valve seat press-fitting part, valve guide press-fitting part, etc., strengthened at one or more places, cases and covers, etc., selected from bolt fastening seat surface, mating surface, etc. And the like strengthened at one or more locations.

It is a perspective view of a metal matrix composite member. It is a principal part expanded sectional view of a metal matrix composite member. It is a perspective view of a ceramic molded body. It is a principal part expanded sectional view of a ceramic molded object. It is manufacturing process explanatory drawing of a ceramic molded body. It is a graph which shows the relationship between the internal diameter of a spherical cell, and its existence probability.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Metal matrix composite member 2 ... Ceramic compact 3 ... Metal matrix 4 ... Spherical cell 5 ... Partition 6 ... Communication hole

Claims (1)

In a high-strength metal matrix composite member comprising a ceramic molded body (2) having a three-dimensional network structure and a metal matrix (3) filled in the ceramic molded body (2), the ceramic molded body (2) is: It has a plurality of spherical cells (4) that are uniform in size and in a dispersed state, and a plurality of communication holes (6) that exist in the partition wall (5) between the adjacent spherical cells (4). The median Md of the inner diameter of the communication hole (6) is Md ≧ 1 μm, and the ratio Md / M _D of the median M _D of the inner diameter of the spherical cell (4) and the median Md of the inner diameter of the communication hole (6). Is set to 0.1 <Md / M _D <0.5.

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