JPS61127847A - Heat movement regulated type composite material - Google Patents

Abstract

PURPOSE:To manufacture the titled material under superior productivity, by casting molten mother material metal into ceramic honeycomb body having a specified shape. CONSTITUTION:A honeycomb body 13 having triangle or octagonal shaped many cells and >=30% porocity is formed with powders or fibers or ceramic having small thermal conductivity. The body 13 is set in mold, molten metal such as Al alloy is cast, pressed statically, and solidified. Not only an Al alloy mother material 12 is packed into each polygons shaped cell of the body 13, but it is permeated even into pores at gap of particle or fiber in said body, and composite material in which the body 13 and the metal 12 are composited in one body is obtd. The titled composite material 11 having small thermal conductivity in Z direction in accordance with cell direction of the body 13 having small thermal conductivity is obtd.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to heat transfer controlled composite materials, which are used as parts of automobile combustion engines, chemical reaction devices, etc. The present invention relates to a heat transfer restricted composite material suitable for effectively restricting or arbitrarily and partially restricting its movement direction.

(Prior Art) In general, members for mechanical structures are often required to have some special properties that cannot be obtained from the constituent materials themselves.

For example, pistons for internal combustion engines are required to be lightweight, so light metal materials such as aluminum and magnesium are usually used. However, these light metal materials have low melting points and poor heat resistance, so in the case of high-output pistons in particular, it is necessary to improve the heat resistance around the piston ring groove, which is the moving part, or to heat load through insulation. reduction is required.

Therefore, as a countermeasure to this problem, in order to improve the heat resistance as shown in (1) above, in the piston 1 having the shape shown in FIG. As shown in Figure 8,
There is a method of arranging a ceramic fiber reinforced member 4 around and above the piston ring groove 2, as described in Japanese Patent Laid-Open No. 52-66222.

However, in the case of disposing the wear ring 3 made of the former Niresist cast iron, although this Niresist cast iron has excellent heat resistance, the specific gravity of the aluminum alloy (for example, JIS: AC8A) that is the material of the piston 1 is 2.7 Since the specific gravity of this Niresist cast iron is 7.6, the piston 1
There is a problem that the weight of the machine increases.

In addition, in the latter case where the ceramic fiber reinforced member 4 is provided, the heat resistance in the vicinity of the piston ring groove 2 is attempted to be improved. If the content of ceramic fibers in the fiber-reinforced portion is increased, the difference in thermal expansion and contraction between the material of the piston 1 and the material of the piston 1 will be significantly different, and under thermal cycles such as during operation, the portion of the reinforcing member 4 and the piston It is not possible to increase the content of fibers in the reinforcing member 4 because problems such as peeling tend to occur at the interface with the material part 1. The problem was that there were limits to sexual improvement, and much could not be expected.

On the other hand, in order to reduce the heat load due to insulation as shown in (■) above,
As shown in FIGS. 9 and 10, a material with excellent heat and heat insulation properties such as ceramics or refractory metal is provided on the piston head crown surface of the piston 1.
Various attempts have been made to reduce the amount of heat flowing into the air. Among these, the method shown in FIG. 9 is a method in which a ceramic flat plate body 5 is formed in advance and this flat plate body 5 is connected to the head portion of the piston 1 by bolting or caulking. 1 is a method of providing a ceramic coating layer 6 on the head portion of the piston 1 by a surface coating method such as thermal spraying or anodic oxidation.

However, in the method shown in FIG. 9, since the coefficient of thermal expansion of the ceramic forming the flat plate 5 is generally significantly different from that of the aluminum alloy, etc. forming the piston 1, the ceramic flat plate 5 is It has the disadvantage that it is easily cracked or damaged, and therefore it is very difficult to increase its durability.

Furthermore, since the ceramic flat plate body 5 has poor workability, it also has the disadvantage that the cost for finishing it into a predetermined shape is high.

On the other hand, in the surface coating method shown in Figure 10, for example, when using anodization, the thickness can only be increased to about 0.1 cm at most, and this thickness does not provide sufficient heat insulation and fire resistance. The disadvantage is that it cannot be obtained. In addition, in the thermal spraying method, it is possible to increase the film thickness to about 2+am, but in this case, due to the difference in thermal expansion with the piston 1, as in the case of using the ceramic flat plate 5 described above, The reality is that the ceramic coating layer 6 cracks and peels during use, resulting in poor durability.

Therefore, based on this background, there has been a demand for the development of a material that can reduce the heat load on required parts by regulating the direction of movement of heat flow.

(Object of the invention) This invention was made in view of the above-mentioned circumstances.
It is possible to control the direction of movement of heat flow, or to arbitrarily and partially control the direction of movement of heat flow, and to provide a composite material with good durability and productivity. This is the purpose.

(Structure of the Invention) The heat transfer controlled composite material according to the present invention includes a base metal,
By combining a ceramic honeycomb body made of ceramic particles or ceramic TA fibers with lower thermal conductivity than the base metal, the direction of movement of heat flow can be regulated or the direction of movement of heat flow can be arbitrarily changed. More preferably, in one embodiment, the porosity inside the ceramic honeycomb body is 30 percent or more, and the pores inside the ceramic honeycomb body are filled with the base material. It is characterized by being able to prevent interfacial peeling due to differences in thermal expansion by impregnating the metal.

When manufacturing the heat transfer controlled composite material according to the present invention, for example, a ceramic honeycomb body made of ceramic particles and/or ceramic fibers, preferably having a porosity of 30 percent or more, is placed at a required location inside the mold. In the arranged state, a base metal molten metal is supplied into the mold, and by applying hydrostatic pressurizing force to the molten metal, each cell of the ceramic honeycomb body is filled with the base metal molten metal. The base metal molten metal is allowed to penetrate into the pores inside the ceramic honeycomb body to sufficiently bond the ceramic honeycomb body and the base metal.

FIG. 1 is a partial explanatory diagram of a heat transfer restricted composite material according to an embodiment of the present invention, and this heat transfer restricted composite material 11 includes a base metal 12 and a ceramic honeycomb body 13.
It is a combination of the two.

In the composite material 11 having such a structure, the base metal 12
Therefore, it is sufficient to select a metal material according to the characteristics required for a part using this composite material 11. Also,
Since the metal material used as the base metal 12 is to be compositely integrated with the ceramic honeycomb body 13, it is desirable to select a metal material that has good composite properties with the ceramic honeycomb body 13. As such a base metal 12, for example, an aluminum metal,
Magnesium-based metals, copper-based metals, zinc-based metals, iron-based metals, etc. are used.

On the other hand, the ceramic honeycomb body 13 is formed from ceramic particles or ceramic fibers, as described later, and the ceramic particles or ceramic fibers are selected from those having lower thermal conductivity than the base metal 12. Ru. The ceramic honeycomb body 13 can be a flexible honeycomb structure in which each cell has a hexagonal shape in the usual sense, as shown in FIG. 2, for example, but in the present invention, The shape of each cell is not limited to such a hexagonal shape, but may be a triangular, square, pentagonal, hexagonal, or other shape as long as it is an integral structure.

Furthermore, the porosity of the ceramic honeycomb body 13 is 3Q
It is more desirable that it be equal to or higher than the percent. The reason for this is that if the porosity of the ceramic honeycomb body 13 is too small, it becomes difficult for the base metal 12 to penetrate into the inside of the ceramic honeycomb body 13.
Not only does interfacial peeling occur at the interface between the base metal 12 and the ceramic honeycomb body 13 under thermal cycling, which causes durability problems, but also
This is because the processability of No. 3 deteriorates, which tends to increase costs when finishing into a predetermined shape.

As described above, the heat transfer-regulated composite material 11 according to the present invention has a structure in which the base metal 12 and the ceramic honeycomb body 13 are integrated into a composite body.
A honeycomb-shaped wall having a lower thermal conductivity than the base metal 12 is disposed, which facilitates the movement of heat flow in the Z direction in FIG. 1, that is, in the cell direction of the ceramic honeycomb body 13. At the same time, X-Y
This makes it difficult to move in the plane direction.

Various specific processes can be considered for manufacturing the heat transfer-regulated composite material 11 having such a configuration.
Among them, more preferable manufacturing examples will be explained.

First, a ceramic honeycomb body 13 made of ceramic particles and/or ceramic fibers with low thermal conductivity and having the shape shown in FIG. 2 is manufactured in advance. At this time, it is desirable that the porosity inside the ceramic honeycomb body 13 be 30% or more, and for this reason, when extrusion molding is used, the amount of binder etc. in the extruded raw material made of ceramics is controlled. do. Then, this ceramic honeycomb body 13 is processed into the size and shape of the honeycomb composite part in the final product.

Next, this ceramic honeycomb body 13 is placed at a predetermined location on the inner surface of the mold, that is, at a portion corresponding to the composite position in the final product, and in this state, molten metal such as aluminum alloy is poured into the mold and hydrostatic pressure is applied. Apply pressure. As a result, not only each cell portion of the ceramic honeycomb body 13 is filled with molten metal, but also the gaps between particles or fibers in the ceramic honeycomb body 13 are filled with the molten metal.
In other words, the molten metal penetrates into the pores in the ceramic honeycomb body 13, and when the cast product is taken out from the mold after solidification, the ceramic honeycomb body 13 and the base material are mixed at a predetermined location (in part or in whole) of the cast product. A material in which the metal 12 is sufficiently integrated is obtained.

Next, by machining the cast product as necessary, a product using the heat transfer controlled composite material 11 according to the present invention is obtained.

In the manufacturing method as described above, the base metal 12 and the ceramic honeycomb body 13 are integrally composited, and the metal in the cells of the ceramic honeycomb body 13 and the metal in the pores of the ceramic honeycomb body 13 interact with each other ( Because it is continuous, the bonding strength between the ceramic honeycomb body 13 and the base metal 12 is extremely high, and there is considerably less risk of peeling at the contact interface unlike in the past, and it is also advantageous in terms of manufacturing because it requires fewer man-hours. Furthermore, by machining the ceramic honeycomb body 13, the cell direction of the ceramic honeycomb body 13 placed in the mold can be arbitrarily determined, so that the direction of movement of heat flow can be regulated.
It is easily possible to arbitrarily change the direction of movement of heat flow.

(Example) Examples of this invention are shown below.

<Example 1> Cordierite (composition; 2Mg0・2A1203・
5Si02) ceramic honeycomb body (cell shape:
Rectangle, number of cells = 400 cells/1nch2. Wall thickness: 0.1
5mm, porosity = 35%), and then a diameter of 100mm.
+am, and processed into a disk shape with a thickness of 25 mm. Next, this was placed on the inner surface of a mold having a casting space of 100 m in diameter, and a JIS ACIA aluminum alloy molten metal was poured into the casting space, and a metal block with a diameter of loom mm and a thickness of 50 m was created.

Next, a thermal conductivity test piece was cut out from the honeycomb composite part of the metal block and the thermal conductivity was measured. cal/cmsse
c * “0, 4 c in the X direction (horizontal direction)
al/CIl@sec@'0. Also, the thermal conductivity of ACIA alloy itself is 28 cat/c
m++Sec・℃. Therefore, based on these characteristics, it was confirmed that the heat flow easily moves in the Z direction, that is, in the cell direction of the honeycomb body, and is difficult to move in the x-y plane direction.

Furthermore, when the metal structure of the metal block was examined in the X-Y direction, the results shown in Figure 3 were obtained, confirming that the base metal had sufficiently penetrated into the pores of the ceramic honeycomb body. .

<Example? > In this example, 94 weight percent A! ;Lz03-
Short fiber ceramic fibers having a composition of Si02 (4ffrffi%%) with an average fiber length of 250 zm and a tJiJ fiber diameter of 3 m, and α-A with an average particle size of 0.087 zm
2203 particles and paraffin wax were kneaded and a ceramic honeycomb body was manufactured by extrusion molding.

Next, the obtained ceramic honeycomb body was heated to 1200°C.
The ratio of fibers in the honeycomb body is 5% by volume.

The ratio occupied by particles was 45% by volume, and the remaining 50% was pores.

Next, the ceramic honeycomb body is placed in the piston head of a high-pressure solidification casting mold for producing pistons, and then a JIS AC8A molten aluminum alloy is supplied into the mold, and this molten alloy is pressurized. Fourth
As shown in the figure, a piston rough material 15 having a ceramic honeycomb body 13 in the head portion was produced. Next, a piston for an internal combustion engine was manufactured by machining the entire body along the machining edges shown in FIG.

Subsequently, the piston thus obtained was installed in a gasoline engine and the following actual test was conducted to examine the performance and durability of the piston. That is, 4 cylinder 2000
In a cc gasoline engine, 420Orpm20
The engine was operated for a total of 200 hours by alternating periods of 10 minutes and 10 minutes of idling, and the temperatures around the first and t52 ring grooves were checked, and the condition of the honeycomb composite portion of the piston head was also observed. Note that the temperature around the ring groove was investigated by the tempering hardness method. The results are shown in Figure 5.
As shown in the figure, the temperature around the first ring groove is about 230~
The temperature was 240°C. Furthermore, the honeycomb composite part of the piston head was examined using a color check method, but no abnormalities were found.

(Comparative example) A piston rough material was created in almost the same manner as in Example 2 without placing the ceramic honeycomb body in a casting mold for piston production, and after being machined, an actual machine test similar to that in Example 2 was conducted. went. The temperature measurement results are shown in FIG. As shown in Figure 6, the temperature around the first ring groove is approximately 240~26
It was 0°C.

From the results shown in FIGS. 5 and 6, it is clear that the heat transfer controlled composite material according to the present invention satisfactorily fulfills its function. In other words, the reason why the temperature measurement result in FIG. 5 is lower than the result in FIG. 6 is that it penetrates into the composite part of the ceramic honeycomb body! *! This result is thought to be because the amount moves less toward the ring groove, moves more toward the cells of the honeycomb body, that is, toward the back side of the piston crown surface, and is released from the back side of the piston crown surface. .

In addition, since ceramics generally have a lower coefficient of thermal expansion and higher hardness than metals, combining the ceramic honeycomb body with the piston crown surface in this way reduces the thermal expansion and increases the pressure resistance of the piston crown surface. This has the advantage that it is possible to achieve improvements such as improvements in performance.

In Examples 1 and 2, an aluminum alloy is used as the base metal, but it is clear that the same method can be used when a magnesium alloy, a copper alloy, or the like is used.

In addition, although the above embodiments show the case where it is applied to a piston head, the heat transfer controlled composite material according to the present invention can be used in various other automobile parts such as cylinder heads and cylinder blocks, as well as in non-automobile parts. Applicable to

(Effects of the Invention) As explained above, the heat transfer controlled composite material according to the present invention is a composite of a base metal and a ceramic honeycomb body having a lower thermal conductivity than the base metal. Because of this, it is possible to effectively restrict the direction of movement of heat flow in the member, or it is also possible to arbitrarily and partially restrict the direction of movement of heat flow. Because the infiltrated base metal and the base metal in the cells of the ceramic honeycomb body are integrated, it exhibits excellent durability against thermal cycles. In addition, since a composite material having such excellent properties can be manufactured relatively simply and easily, a significant effect is brought about in that the composite material has excellent manufacturability.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a slope showing the structure of a heat transfer-regulated composite material according to an embodiment of the present invention, 2nd rI! J is also a slope explanatory diagram showing an example of the structure of a ceramic honeycomb body, the third
The figure is an enlarged photograph showing the metal structure in the x-y direction of Figure 1 of the heat transfer controlled composite material manufactured in this example.
FIG. 4 is an explanatory diagram showing the composite state of the ceramic honeycomb body, especially in the piston crown, of the piston rough material manufactured in the example of this invention, and FIG. 5 is a temperature distribution measurement of the piston manufactured in the example of this invention An explanatory diagram showing the results. Figure 6 is an explanatory diagram showing the temperature distribution measurement results of a conventional piston as a comparative example. Figure 7 is a cross section of a conventional piston in which a wear-resistant ring made of Niresist cast iron is arranged around the first binuton ring groove. Figure 8 is a cross-sectional diagram of a conventional piston in which fiber reinforcement is applied around and above the first piston ring groove, and Figure 9 is a cross-sectional diagram of a conventional piston in which a ceramic flat plate is disposed in the piston head. 10 are explanatory cross-sectional views of a conventional piston whose piston head is coated with ceramics. 11... Heat transfer controlled composite material, 12... Base metal. 13... Ceramic honeycomb body. Patent Applicant Nissan Motor Co., Ltd. Representative Patent Attorney Yutaka Oshio 13 eLami 1. ΔAlso Honeycomb Fig. 3 (X100) Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Manabu Ka 1, Indication of the case 1982 Patent Application No. 248349 2, Name of the invention Heat transfer controlled composite material 3, Relationship with the person making the amendment Name of patent applicant (name) (3913) Nissan Motor Co., Ltd. Company 4, agent address (residence) Kobikikan Ginza Building, 2-8-9 Ginza, Chuo-ku, Tokyo 104 Telephone: 03 (587) 2761 (Representative) 03 (5B?) 7933 (Gllll) 6, Correction The number of inventions increased by 7, the drawings to be amended in Figure 3, 8, and the contents of the amendment in Figure 3 are corrected as shown in the attached sheet. (×10■

Claims (2)

[Claims] (1) A heat transfer-regulated composite material comprising a base metal and a ceramic honeycomb body having a lower thermal conductivity than the base metal. (2) The heat transfer controlled composite material according to claim (1), wherein the ceramic honeycomb body has a porosity of 30% or more, and the base metal penetrates into the pores of the honeycomb body.