JP5462618B2 - Manufacturing method of composite material - Google Patents

Description

  The present invention relates to a method for producing a composite material comprising a boron carbide reinforcement and a metallic silicon matrix.

In recent years, composite materials of boron carbide reinforcement and metal silicon matrix (hereinafter, B ₄ C / Si composite materials) have been used in various fields. In the manufacturing process of such a composite material, when metal boron is impregnated into a boron carbide preform, it may react with the boron carbide reinforcing material to cause cracks. And the manufacturing method of the boron carbide composite body for preventing such a crack is proposed (for example, refer patent document 1).

  In the method for producing a boron carbide composite described in Patent Document 1, infiltration is performed in the absence of a reactive carbonaceous component to produce siliconized boron carbide. Then, before the silicon infiltrant contacts the boron carbide, the boron carbide and the silicon being infiltrated can be reacted by alloying or dissolving the boron source or carbon source or both boron and carbon in the silicon. Suppressed.

Special table 2007-513854 gazette

  9 and 10 are cross-sectional views showing one scene of a method for producing such a conventional boron carbide composite. As shown in FIGS. 9 and 10, boron carbide preform 930 and boron carbide-containing material 940 are placed in container 910, and molten metal 950 is contained in preform 930, so that the above boron carbide composite The body can be manufactured.

  However, in the method for producing the boron carbide composite described in Patent Document 1, the boron carbide preform is impregnated in the silicon carbide preform by dissolving the boron carbide component in the metal silicon in advance. Cracks are likely to occur.

  This invention is made | formed in view of such a situation, and it aims at providing the manufacturing method of the composite material which can reduce reaction at the time of preform impregnation, and can prevent generation | occurrence | production of a crack.

  (1) In order to achieve the above object, a method for producing a composite material according to the present invention is a method for producing a composite material comprising a boron carbide reinforcement and a metal silicon matrix, which is separated from a boron carbide preform. Then, the boron carbide-containing material is mixed and pre-dissolved in molten metal silicon, and the preform is impregnated with the pre-dissolved material mixed with the boron carbide-containing material.

  Thus, by dissolving boron carbide in metal silicon before impregnation with metal silicon, the reaction at the time of impregnation into the preform can be reduced, and cracks can be prevented.

  (2) The method for producing a composite material according to the present invention is a method for producing a composite material comprising a boron carbide reinforcing material and a metal silicon matrix, and allows the molten metal to penetrate into the outer container. Installing a boron carbide preform outside the inner container in the outer container, placing metal silicon and boron carbide-containing material in the inner container, and melting the metal silicon in the inner container The boron carbide-containing material is mixed with molten metal silicon and pre-dissolved to produce a pre-dissolved material, the inner container is infiltrated into the pre-dissolved material, and the pre-dissolved material that has permeated the inner container is And a step of impregnating the preform.

  In this way, boron carbide is dissolved in molten metal silicon in the inner container in advance, and the preform is impregnated using the penetration of the pre-dissolved material from the inner container, thereby reducing the reaction during the impregnation of the preform. And cracking can be prevented.

  (3) Moreover, the manufacturing method of the composite material of this invention is characterized by the said inner container being formed with the sheet | seat made from carbon. Thereby, since molten silicon reacts with carbon and permeates the inner container, it is possible to impregnate the preform with molten metal.

  According to the present invention, the reaction at the time of impregnation with a preform can be reduced and the occurrence of cracks can be prevented.

It is a top view which shows one scene of the manufacturing method of the composite material which concerns on 1st Embodiment. It is sectional drawing which shows one scene of the manufacturing method of the composite material which concerns on 1st Embodiment. It is sectional drawing which shows one scene of the manufacturing method of the composite material which concerns on 1st Embodiment. It is sectional drawing which shows one scene of the manufacturing method of the composite material which concerns on 1st Embodiment. It is sectional drawing which shows one scene of the manufacturing method of the composite material which concerns on 1st Embodiment. It is sectional drawing which shows one scene of the manufacturing method of the composite material which concerns on 2nd Embodiment. It is sectional drawing which shows one scene of the manufacturing method of the composite material which concerns on 2nd Embodiment. It is sectional drawing which shows one scene of the manufacturing method of the composite material which concerns on 2nd Embodiment. It is sectional drawing which shows one scene of the manufacturing method of the conventional composite material. It is sectional drawing which shows one scene of the manufacturing method of the conventional composite material.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, in order to facilitate understanding of the description, the same reference numerals are given to the same components in the respective drawings, and duplicate descriptions are omitted.

[First Embodiment]
The B ₄ C / Si composite material (composite material) according to the present invention comprises a boron carbide reinforcing material and a metal silicon matrix, and has a structure in which the reinforcing material is dispersed in the matrix. B ₄ C / Si is obtained by impregnating metallic silicon into a boron carbide (B ₄ C, boron carbide) preform. The metal silicon used may be a simple substance or an alloy. The B ₄ C / Si composite material is substantially composed of a boron carbide reinforcing material and a metal silicon matrix, and may contain some impurities.

  FIG. 1 is a plan view showing one scene of a method for manufacturing a composite material, and FIGS. 2 to 5 are cross-sectional views showing one scene of a method for manufacturing a composite material. As shown in FIGS. 1 and 2, first, an inner container 120 is installed in the outer container 110, and a preform 130 made of a ceramic porous body of boron carbide outside the inner container 120 in the outer container 110. Is installed. FIG. 2 is a cross-sectional view of the cross section A of FIG. 1 as viewed from the direction of the arrow.

  The outer container 110 is a container having a bottomed opening, and holds the metal when the molten metal silicon 150 is impregnated. The inner container 120 is a container having a bottomed opening and can hold molten metal, but the wall of the container is formed of a porous body having a fine pore diameter. Therefore, it permeates by permeation after a predetermined time while holding the molten metal. Thus, it is preferable that the inner container 120 is capable of separating the molten metal for a predetermined time. Such an inner container 120 can be produced by folding a carbon sheet. Thereby, when the molten metal silicon 150 is melted, the molten metal reacts with the carbon and penetrates the inner container, so that the preform can be impregnated with the molten metal that has passed through the inner container 120.

  The carbon sheet is preferably a porous body having a specific gravity of about 1, and the thickness in that case is preferably about 0.4 to 0.8 mm. The inner container 120 may be one in which a fine hole is made in a box of boron nitride having poor wettability with metal silicon and the pre-dissolved material is leached. As described above, the inner container 120 is not necessarily limited to the above-described form, and may prevent pre-dissolution of the boron carbide-containing material into the metal silicon 150 and impregnation of the pre-dissolution material into the preform 130. Any partition may be used.

  Next, the boron carbide-containing material 140 and the metal silicon 150 are placed in the inner container 120, and the metal silicon 150 is melted as shown in FIG. The boron carbide-containing material 140 only needs to be contained in a predetermined ratio or more with respect to the metal silicon 150 to be melted, and may be an end material of a B4C / Si composite material, for example. The boron carbide-containing material 140 may be in the form of a mass or powder, but preferably contains 40% or more of boron carbide by weight.

  Thereby, as shown in FIG. 4, the boron carbide-containing material 140 is dissolved and reacted with the metal silicon 150 separated before the impregnation, and the pre-dissolved material 155 is generated. Thus, by dissolving the material constituting the preform into the metal before impregnation, the reaction during the impregnation of the preform 130 can be reduced, and cracks can be prevented.

  Next, when the time is exceeded, the pre-dissolved material 155 oozes out from the side wall of the inner container 120. Then, as shown in FIG. 5, the preform 130 is impregnated with the pre-dissolved material 155. In the impregnation step, a jig may be provided so that the molten metal silicon 150 is not in direct contact, and the preform 130 may be floated from the bottom of the outer container 110.

  Next, the inside of the outer container 110 is naturally cooled and cooled to room temperature. The composite material 160 can be obtained by separating the composite material 160 cooled in this way from the outer container 110 and taking it out. The obtained composite material 160 can be used as an impact resistant material, for example.

[Second Embodiment]
In the above embodiment, the preform 130 is directly impregnated with the pre-dissolved material 155. However, a B ₄ C / Si composite material setter may be interposed between the two in consideration of the thermal expansion coefficient. Since the thermal expansion coefficient of boron carbide is 4.5 × 10 ⁻⁶ / K and the thermal expansion coefficient of silicon is 2.6 × 10 ⁻⁶ / K, the thermal expansion coefficient of metal silicon is the carbonization that forms the reinforcement. The thermal expansion coefficient is smaller than that of boron, and the relationship of (thermal expansion coefficient of metallic silicon) <(thermal expansion coefficient of composite material) <(thermal expansion coefficient of boron carbide) is established. The thermal expansion coefficient of B ₄ C / Si is 3.0 × 10 ⁻⁶ / K.

  6 to 8 are cross-sectional views showing one scene of the method for manufacturing the composite material 260. As shown in FIG. 6, a setter 270 is first laid in the outer container 110, and a ceramic porous boron carbide preform 130 is placed on the setter 270.

  Next, as shown in FIG. 7, the metallic silicon 150 installed in the inner container 120 is melted. Then, the boron carbide-containing material 140 is dissolved in the metal silicon 150 in the inner container 120 and reacted in advance. The preform 130 thus produced is impregnated into the preform 130 through the setter 270. Because the preform 130 is impregnated with the pre-dissolved material 155 via the setter 270, the composite material 260 does not contact the residual metal silicon 150 directly.

The pre-melting material 155 is mainly composed of metallic silicon and has a thermal expansion coefficient smaller than that of the ceramic forming the preform 130. Therefore, the thermal expansion coefficient of the pre-dissolved material 155 to be impregnated is smaller than the thermal expansion coefficient of the resulting composite material 260. If the setter 270 is not provided, a tensile force is generated in the composite material 260 due to the shrinkage of the composite material 260 at the time of cooling. However, in this embodiment, the setter 270 of the B ₄ C / Si composite material is provided. Can be reduced. In addition, a jig may be provided on the setter 270 so that the pre-dissolved material 155 does not come into direct contact, and the preform 130 may be floated from the setter 270.

  Next, as shown in FIG. 8, the inside of the outer container 110 is naturally cooled and cooled to room temperature. The composite material 260 contracts together with the setter 270 and the pre-dissolved material 155 by cooling, but the contraction rate differs depending on the material. The shrinkage rate of the composite material 260 is closer to that of the setter 270 than the metal silicon 150. Accordingly, the setter 270 is subjected to a tensile force due to the metal silicon 150, but the tensile force acting on the composite material 260 is only due to the setter 270 and is reduced. As a result, cracks are less likely to occur in the formed composite material 260. The composite material 260 can be obtained by separating the composite material 260 thus cooled from the setter 270 and taking it out.

  In addition, what is formed with the boron carbide ceramic porous body as said setter 270 can also be used. In that case, when the preform 130 is impregnated with the pre-dissolved material 155 through the setter 270, the pre-dissolved material 155 is also impregnated into the setter 270.

  Also in this case, the setter 270 impregnated with the pre-dissolved material 155 comes into direct contact with the composite material 260, and the composite material 260 does not come into contact with the residual metal silicon 150. The relationship of (metal thermal expansion coefficient) <(thermal expansion coefficient of the setter after the impregnation process) is established, and the setter 270 after being used in the impregnation process has a heat higher than that of the composite material 260 to be manufactured. Has an expansion coefficient. Therefore, the composite material 260 receives a small tensile force due to a difference in thermal expansion from the outside during cooling, and the composite material 260 is less likely to crack.

  In this way, the setter 270 made of a material similar to the composite material 260 or having a smaller thermal expansion difference from the preform 130 than the pre-melted material 155 is spread and penetrated under the preform 130, thereby reducing the tensile force due to cooling shrinkage. Is done. And the crack of the composite material 260 which generate | occur | produces from the influence in the residual alloy at the time of metal impregnation of the composite material 260 can be suppressed. In particular, when the composite material 260 is used as an impact-resistant member, a defect such as a crack is also related to human life, so that the effect is great.

  (Example)

A slurry obtained by pouring a slurry obtained by mixing 12.8% as a binder and 60% water into a commercially available boron carbide powder (average particle diameter 23 μm, purity 95% or more) into a mold is fired at 150 ° C., and density 1. A 30 g / cm ³ boron carbide preform was prepared. The prepared preform was placed in the outer container 110. In addition, in an inner container formed by folding a carbon sheet, a B ₄ C / Si composite material as a boron carbide-containing material and an amount of silicon alloy necessary for impregnation were placed. Then, the silicon alloy is melted by heating at 1,410 ° C. for 4 hours, and then heated at 1,550 ° C. for 24 hours to allow the pre-dissolved material to permeate from the inner container, and at the same time, further permeate the pre-dissolved material. The reform was impregnated.

Impregnation was performed in the same manner as in Example 1 except that a preform was placed on a setter of B ₄ C / Si composite material.

(result)
As Example 1, it was possible to obtain a composite material having no altered portion due to SiC or the like. In the composite material of Example 1, no crack was found. In Example 2, it was possible to infiltrate without contacting the residual alloy by installing a setter. There were no defects such as cracks in the composite material of Example 2.

110 Outer container 120 Inner container 130 Preform 140 Boron carbide containing material 150 Metallic silicon 155 Pre-melting material 160, 260 B ₄ C / Si composite material (composite material)
270 setter

Claims (2)

A method for producing a composite material comprising a boron carbide reinforcement and a metallic silicon matrix,
An inner container that allows permeation of molten metal is installed in the outer container, a boron carbide preform is installed outside the inner container in the outer container, and a metal-silicon and boron carbide-containing material is installed in the inner container. Process,
Melting the metal silicon in the inner vessel, mixing the boron carbide-containing material with the molten metal silicon and pre-dissolving to produce a pre-dissolved material;
A method of manufacturing a composite material, comprising: impregnating the inner container into the pre-dissolved material, and impregnating the preform with the pre-dissolved material that has permeated the inner container. The method for producing a composite material according to claim 1 , wherein the inner container is formed of a carbon sheet.

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