JP3885061B2 - Manufacturing method of composite material - Google Patents

Description

  The present invention relates to a method for manufacturing a composite material in which a dispersoid is dispersed in a part of a workpiece to make the portion into a composite material.

  A cylinder head constituting an internal combustion engine of a diesel automobile is usually manufactured by gravity casting (GDC) or low pressure casting (LPDC) using a molten aluminum alloy as a raw material, and faces a cylinder block unlike a cylinder head of a gasoline automobile. The side surface is formed flat.

  As is well known, when a piston reciprocates in a cylinder bore of an internal combustion engine, a piston ring provided on the piston is in sliding contact with an inner peripheral wall surface of the cylinder bore. Further, as the piston reaches top dead center, the air-fuel mixture introduced into the cylinder bore and the vaporized fuel are compressed, and then the air-fuel mixture explodes. For this reason, high stress acts on the inner peripheral wall surface of the cylinder bore and the cylinder head.

  Since such a phenomenon is repeated, high rigidity is demanded in order to avoid the occurrence of cracks in a portion where high stress acts on the cylinder head, specifically between valve seats. Therefore, it is originally preferable to manufacture the cylinder head from a highly rigid material, for example, a metal matrix composite (MMC) in which ceramics are dispersed in a metal material.

  However, high stress is rarely applied to other parts of the cylinder head. Therefore, if the entire cylinder head is made of MMC or the like in order to satisfy the high rigidity required for some parts, the cost increases. Invite. In addition, MMC has a problem that it is not easy to process.

  From such a viewpoint, Patent Document 1 proposes that friction stirring is performed between valve seats in the cylinder head, and further heat treatment is performed.

JP 2001-181809 A

  However, the technique disclosed in Patent Document 1 only performs surface modification by homogenizing the fine structure by friction-stirring meat at a predetermined site. In this case, the characteristics of the surface are determined by the material, and it is not possible to obtain characteristics superior to those inherent to the material. That is, for example, it is not possible to obtain a strength higher than the theoretical strength indicated by the material.

  The present invention has been made in order to solve the above-described problems, and is a composite material that can easily improve various characteristics required according to the site by an easy and simple operation and at low cost. An object is to provide a manufacturing method.

In order to achieve the above object, the present invention provides a method for producing a composite material in which ceramic as a dispersoid is dispersed in a part of a work made of aluminum, aluminum alloy, magnesium or magnesium alloy to form a composite material. Because
Placing the dispersoid raw material to be dispersed on the workpiece together with the metal source of the same composition or aluminum alloy as the workpiece;
By using a tool to which a pressing force of 1 to 10 kN is applied, the raw material and the meat of the workpiece are frictionally agitated together , whereby the raw material is used as a dispersoid and the metal is contained in a proportion of 3 to 60% by volume in the workpiece. Dispersing with the source ;
It is characterized by having. Here, friction agitation refers to softening the workpiece meat by frictional heat and causing plastic flow, and, for example, a technique employed in friction agitation joining in which the abutting end surfaces of two members are joined together. It is.

  According to the present invention, the dispersoid is dispersed in a predetermined part of the work by performing an easy and simple operation of friction stirring the raw material and the meat of the work, and thus the characteristics of the predetermined part are improved. A composite material can be obtained. Therefore, since it is not necessary to constitute the entire member with a material having excellent characteristics, it is possible to avoid an increase in cost.

  In addition, the friction stirrer can plastically flow without melting the workpiece flesh, so that defects such as so-called blowholes do not occur in the work after the friction stir. Further, since the low melting point component of the work is not vaporized, the work composition is not changed and the work is not altered.

  Furthermore, since the workpiece is not melted, there is an advantage that the residual stress can be reduced and the distortion of the workpiece can be reduced.

  Desired characteristics can be improved by appropriately selecting the type of dispersoid. Therefore, in the present invention, for example, the wear resistance can be improved in one part and the lubricity can be improved in another part, and the characteristics to be improved can be made different depending on the part.

  As the raw material, for example, a plate material produced by sintering or casting may be used.

  Or you may make it use powder as a raw material. In this case, in order to prevent the powder from being lost before friction stirring, it is preferable that the powder is previously attached to the workpiece by thermal spraying. Friction stirring between the powder and the workpiece may be performed while supplying the powder.

Suitable examples of the dispersoid include ceramics. For example, when Al ₂ O ₃ or SiC is selected, a composite material having a portion with improved wear resistance can be obtained. Moreover, when BN, C, etc. are selected, lubricity improves.

  When ceramics is used as a dispersoid, it is preferable that the raw material contains the same composition as the workpiece or metal powder of aluminum in advance. In this case, the flesh and dispersoid of the work can be easily plastically flowed, and eventually the dispersoid can be easily dispersed in the work.

  Moreover, it is preferable that the ratio of this dispersoid in the area | region where ceramics (dispersoid) disperse | distributed in the workpiece | work is 3-60 volume%. If it is less than 3% by volume, the effect of improving the properties of the workpiece is poor, and if it exceeds 60% by volume, it is not easy to process the composite material. Here, the dispersed region of the dispersoid refers to a region formed by connecting the highest reaching points of the dispersoid.

  On the other hand, a preferable example of the workpiece is an aluminum alloy that is a material of the cylinder head.

  According to the present invention, the dispersoid is dispersed in the work by performing frictional stirring. Thereby, a composite material with improved characteristics of a predetermined part can be obtained easily and simply. In addition, for this reason, it is not necessary to configure the entire member such as the cylinder head from materials having excellent characteristics, so that the cost is not increased.

  In addition, by appropriately changing the type of dispersoid to be dispersed, desired characteristics can be improved, and members having different characteristics required depending on the site can be easily and easily obtained.

  Hereinafter, preferred embodiments of a method for producing a composite material according to the present invention will be described in detail with reference to the accompanying drawings.

  First, a first embodiment using a plate material will be described.

  In the method for manufacturing a composite material according to the first embodiment, a friction stir welding tool 10 is used as shown in FIG. The friction stir welding tool 10 includes a rotating body 12 that is connected to a spindle (not shown) and rotates when the spindle is urged to rotate, and a probe 14 provided at the tip of the rotating body 12. Have. As will be described later, the workpiece 16 and the plate member 18 are integrally frictionally stirred under the action of the friction stir welding tool 10.

  As shown in FIG. 2, the lateral width w of the plate member 18 is set smaller than the diameter Ds of the rotating body 12. The diameter Dp of the probe 14 is not particularly limited, but in this case, the diameter Dp is set larger than the lateral width w of the plate member 18. The thickness t of the plate material 18 is preferably 5 mm or less. The length L of the probe 14 is not particularly limited, but may be, for example, approximately the same as the thickness t of the plate material 18.

  In this case, the workpiece 16 is made of an aluminum alloy, and a plate material 18 which is a dispersoid raw material is placed on the workpiece 16. The plate member 18 is made of a sintered body in which an aluminum alloy powder having the same composition as the workpiece and a ceramic powder are relatively loosely bonded.

As the ceramic powder, a powder of a substance that improves the characteristics of the aluminum alloy may be selected. For example, when it is desired to impart wear resistance to the workpiece 16, Al ₂ O ₃ or SiC can be selected, and when it is desired to impart lubricity, BN or C is selected. can do.

  When carrying out the friction stirring, the spindle is urged to rotate, and the friction stirring welding tool 10 is rotated. Next, the friction stir welding tool 10 is lowered, and the upper end surface of the one end portion of the plate 18 configured as described above is pressed by the probe 14.

  The pressing force at this time is preferably about 1 to 10 kN. At 1 kN, sufficient frictional heat is not generated, so plastic flow does not proceed easily, and therefore, it is not easy for the composite to proceed. Moreover, when it exceeds 10 kN, the workpiece | work 16 may deform | transform.

  As the probe 14 rotated in this manner comes into sliding contact with the plate member 18, frictional heat is generated in the plate member 18 and the sliding contact portion is softened. Further, since a predetermined pressing force is applied to the friction stir welding tool 10, the tip of the probe 14 is buried in the plate material 18. The plate material 18 is finally crushed as shown in FIG. 3, and the tip of the probe 14 is buried in the workpiece 16.

  During this process, since the probe 14 is rotating, the flesh of the workpiece 16 and the plate material 18 are agitated by the probe 14. In other words, the meat of the workpiece 16 and the plate material 18 cause plastic flow, and as a result, the ceramic powder contained in the plate material 18 is dispersed in the workpiece 16. In this case, since the aluminum alloy powder is added to the plate material 18, the plastic flow during friction stirring easily proceeds.

  Next, the friction stir welding tool 10 is moved in the direction indicated by the arrow X in FIG. 1 in a state where the rotational urging of the friction stir welding tool 10 is continued. Along with this, cooling and solidification occurs at the location where the probe 14 is separated, and thereby a composite material in which ceramic powder is dispersed as a dispersoid in the workpiece 16 which is an aluminum alloy is formed.

The characteristics that are improved at the site where the dispersoid is dispersed (dispersion region) vary depending on the type of ceramic powder. As described above, the wear resistance is improved when the dispersoid is Al ₂ O ₃ or SiC, and the lubricity is improved when it is BN or C.

  On the other hand, at the portion where the displaced probe 14 approaches, plastic flow occurs as the meat of the workpiece 16 and the plate 18 are agitated. As a result, as described above, the ceramic powder is contained in the workpiece 16. Dispersed as a dispersoid. Even in this portion, cooling and solidification occur after the probe 14 is separated. By repeating this phenomenon sequentially, the dispersoid is dispersed in the workpiece 16 along the displacement direction (arrow X direction) of the probe 14.

  As shown in FIG. 3, burrs 20 and recesses 22 are formed when the plate material 18 is crushed. These are removed by finishing.

Here, the B scale Rockwell hardness (HRB) and the Young's modulus (E) improvement rate in the workpiece 16 in which Al ₂ O ₃ is dispersed as the dispersoid are connected to the highest reach points of the dispersoid. FIG. 4 also shows the relationship with the ratio of the dispersoid in the formed dispersion region. In FIG. 4, the symbol ■ represents HRB, and the symbol ● represents the improvement rate of E.

  As can be seen from FIG. 4, as the proportion of the dispersoid in the dispersed region increases, the hardness and Young's modulus of the dispersed region improve. However, when the proportion of the dispersoid is excessively increased, it becomes difficult to process the obtained composite material into a predetermined shape, such as flattening the dispersion region. In order to avoid such a situation, the proportion of the dispersoid in the dispersion region is preferably 3 to 60% by volume. If it is less than 3% by volume, the effect of improving various properties of the workpiece 16 is poor.

  A more preferable dispersoid ratio is 20 to 50% by volume. When it is 20% by volume or more, the Young's modulus E is drastically improved. On the other hand, if the volume is within 50% by volume, the probe 14 can be prevented from being worn.

  As described above, according to the first embodiment, the plate material 18 containing the ceramic powder that becomes the dispersoid is placed on the workpiece 16, and then the meat of the workpiece 16 and the plate material 18 with the friction stir welding tool 10 By carrying out an easy and simple work of friction stirring together, the dispersoid is dispersed in the work 16, and thus a composite material with improved characteristics at a predetermined site can be obtained. In other words, desired characteristics can be given only to a certain part. Therefore, it is not necessary to configure the entire member with a material having excellent characteristics in order to express desired characteristics at a predetermined site. For this reason, it is possible to avoid an increase in cost.

  In addition, in this case, since the workpiece 16 is not melted, defects such as so-called blowholes are not generated, and the low melting point component in the alloy component contained in the workpiece 16 is vaporized, and thus the composition and the characteristics of the workpiece 16 are obtained. Does not change.

In addition, the characteristics to be improved can be changed by appropriately changing the type of dispersoid. Therefore, for example, dispersoids that improve wear resistance such as Al ₂ O ₃ and SiC are dispersed in a part where the workpiece 16 is present, while lubricity such as BN and C is improved relative to another part. If the dispersoid to be dispersed is dispersed, it is possible to obtain composite materials having various characteristics depending on the part.

  In the first embodiment, as shown in FIG. 5, the long groove 24 is provided in the workpiece 16 along the displacement direction of the friction stir welding tool 10, and the plate material 18 is inserted into the long groove 24. Alternatively, friction stirring may be performed. Instead of inserting the plate material 18, the ceramic powder and the workpiece 16 may be adhered to each other by thermal spraying after the ceramic powder is accommodated in the long groove 24.

  Furthermore, the plate member 18 is not limited to a sintered body, and is activated by reducing the oxide generated spontaneously on the surface of the metal or ceramics with a reducing gas, and then composited by infiltrating the molten metal. A metal matrix composite (MMC) obtained by a so-called activated permeation method or a material obtained by casting such as a component casting may be used.

  Next, a second embodiment in which powder containing ceramic powder is used as a raw material and friction stirring is performed while the raw material is supplied will be described.

  In the second embodiment, as shown in FIG. 6, a powder supply pipe 30 is attached to a displacement mechanism (not shown) that displaces the friction stir welding tool 10 in the arrow X direction.

  While the friction stir welding tool 10 is rotating in accordance with the first embodiment, the ceramic powder as described above from the powder supply pipe 30 or the mixed powder of the ceramic powder and the aluminum alloy powder, that is, the dispersoid. The powder P, which is a raw material, is supplied to the upper end surface of the workpiece 16. After the powder P is placed on the upper end surface of the workpiece 16 by this supply, the probe 14 of the friction stir welding tool 10 is moved down to slidably contact the workpiece 16.

  In the workpiece 16, the portion where the probe 14 is in sliding contact is softened by frictional heat, and finally the probe 14 is buried in the workpiece 16 while rotating. As the probe 14 is buried in this manner, the meat of the workpiece 16 is plastically flowed together with the powder P.

  Then, the probe 14 is displaced in the direction of the arrow X under the action of the displacement mechanism, and the supply of the powder P from the powder supply pipe 30 is continued until reaching the end point. As described above, since the powder supply tube 30 is attached to the displacement mechanism, the powder supply tube 30 is not detached from the displacement locus of the probe 14.

  Thereafter, as a result of performing frictional stirring in accordance with the first embodiment, a composite material in which ceramic powder (dispersoid) is dispersed in the workpiece 16 along the arrow X direction is obtained.

  As described above, in the second embodiment, the friction stir of the meat of the workpiece 16 is performed by the friction stir welding tool 10 while supplying the powder P containing the ceramic powder as the dispersoid onto the workpiece 16. That is, even in this case, the dispersoid is dispersed in the work 16 by an easy and simple operation, and for this reason, a composite material with improved characteristics of a predetermined part is obtained.

  Of course, also in the second embodiment, if the type of dispersoid is appropriately changed, the characteristics to be improved can be changed, and eventually, composite materials having different characteristics depending on the parts can be obtained.

  In the second embodiment, as shown in FIG. 7, a passage 32 is provided inside the friction stir welding tool 10, and the powder P containing ceramic powder is passed from the tip of the probe 14 via the passage 32. You may make it supply.

  Moreover, also in 2nd Embodiment, it is preferable that the ratio of the dispersoid in a dispersion | distribution area | region is 3-60 volume%, and it is more preferable that it is 20-50 volume%.

  In either the first embodiment or the second embodiment described above, the metal powder may be dispersed as a dispersoid. In this case, depending on the type of metal, it may be dispersed and alloyed with an aluminum alloy that is a constituent metal of the workpiece 16. In the present invention, such alloying of dispersoid and workpiece is included in the composite material.

  Furthermore, the constituent metal of the workpiece 16 is not particularly limited to an aluminum alloy, and may be aluminum, magnesium, a magnesium alloy, or the like.

  Another example of the workpiece 16 is a valve seat, a head surface of a piston constituting a diesel internal combustion engine, and a ring groove.

It is a schematic perspective explanatory drawing which shows the state which implements the manufacturing method which concerns on 1st Embodiment. It is front explanatory drawing which shows the dimension relationship of a workpiece | work, a board | plate material, and the tool for friction stir welding. It is a schematic longitudinal cross-sectional view which shows the state by which the board | plate material was crushed by pressing a probe. And HRB and Young's modulus in the workpiece obtained by dispersing Al ₂ O _3, is a graph showing the relationship between the ratio of the dispersoid in the dispersion region. It is a schematic longitudinal cross-sectional view which shows the workpiece | work and board | plate material for enforcing the manufacturing method which concerns on the modification of 1st Embodiment. It is a schematic perspective explanatory drawing which shows the state which implements the manufacturing method which concerns on 2nd Embodiment. It is a schematic longitudinal cross-sectional view which shows the friction stir welding tool for implementing the manufacturing method which concerns on the modification of 2nd Embodiment, a workpiece | work, and a board | plate material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Tool for friction stir welding 14 ... Probe 16 ... Workpiece 18 ... Plate material 30 ... Powder supply pipe P ... Powder

Claims (4)

A method for producing a composite material in which ceramic as a dispersoid is dispersed into a part of a workpiece made of aluminum, an aluminum alloy, magnesium or a magnesium alloy to form a composite material,
Placing the dispersoid raw material to be dispersed on the workpiece together with the metal source of the same composition or aluminum alloy as the workpiece;
By using a tool to which a pressing force of 1 to 10 kN is applied, the raw material and the meat of the workpiece are frictionally agitated together , whereby the raw material is used as a dispersoid and the metal is contained in a proportion of 3 to 60% by volume in the workpiece. Dispersing with the source ;
A method for producing a composite material, comprising: The manufacturing method of claim 1, wherein method of producing a composite material in which the dispersoid is characterized the dispersoid to Rukoto 20-50% by volume proportion of the region that is dispersed in the workpiece. The manufacturing method according to claim 1 or 2 wherein method of producing a composite material characterized in that the pre-Symbol dispersoid and Al ₂ O ₃ or SiC. The manufacturing method according to claim 1 or 2 wherein method of producing a composite material characterized in to Rukoto and the dispersoid BN or C.

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