JPS628303B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a boiling heat transfer surface, and in particular,
The present invention relates to a method for producing a boiling heat transfer surface, which is aimed at producing a boiling heat transfer surface with excellent corrosion resistance.

Traditionally, boiling heat transfer surfaces have been manufactured by attaching a large number of fine holes to a grooved plate in a thin plate of copper or aluminum, which is a highly thermally conductive material, or by attaching a thin plate made of copper or aluminum, which is a highly thermally conductive material, to a grooved plate, or by attaching a thin plate made of copper or aluminum, which is a highly thermally conductive material, with holes orthogonal to each other. A method of manufacturing by laminating a plurality of metal plates (made of the same copper or aluminum as above) in which multiple grooves are provided and holes are formed at the intersections of the grooves, and a sintered body of fine powder of the metal is manufactured. There are known methods to do this.

However, it is necessary to use materials with good corrosion resistance for boiling heat transfer surfaces used in ocean thermal energy conversion power generation or chemical plants, and for this purpose austenitic stainless steel and titanium-based materials are often used, but these are sufficient in terms of corrosion resistance. The problem was that it was not.

An object of the present invention is to provide a method for manufacturing a boiling heat transfer surface, which eliminates the drawbacks of the prior art described above and can produce a boiling heat transfer surface with excellent corrosion resistance.

The structure of the method for manufacturing a boiling heat transfer surface according to the present invention is as follows:
After drilling a plurality of grooves perpendicularly to each other on the front and back surfaces of a thin sheet of unfired ceramics and having a depth such that an opening is formed at the intersection point by mutual interference, this thin sheet is then cut into the opposite grooves. The method of manufacturing a boiling heat transfer surface involves laminating a plurality of sheets so that they are perpendicular to each other and sintering them at high temperature under pressure.

The present invention will be explained below with reference to an example in which a boiling heat transfer surface is manufactured by laminating two ceramic thin plates.

FIG. 1 is a partial perspective view showing a green sheet used in the method of manufacturing a boiling heat transfer surface according to an embodiment of the present invention, and FIG. 2 is a partial perspective view showing a green sheet according to FIG. FIG. 3 is a partial sectional view showing a state in which grooves are bored by the green sheet according to FIG. 1; FIG. FIG. 4 is a partial perspective view showing a state in which two green sheets according to FIG. 3 are stacked.

First, a thin plate of unfired ceramics (usually called a green sheet) is prepared.

This green sheet 1 is made by dissolving fine ceramic powder in an organic solvent to form a clay-like material.
As shown in the figure, it is formed into a thin plate shape, and has the characteristics of being highly flexible and hard.

Next, grooves are formed on the front and back surfaces of the green sheet 1 using an electron beam or a laser beam, which is a high energy density beam. The method of drilling this groove will be explained using FIG. 2. The method shown in FIG. 2a places the beam focus 5 of the electron beam 4 above the surface of the green sheet 1,
By moving the green sheet 1 in a direction perpendicular to the paper surface, a U-shaped groove 2 is bored. On the other hand, in the method shown in FIG. 2b, the beam focus 5 of the electron beam 4 is placed below the surface of the green sheet 1, and the green sheet 1 is moved in a direction perpendicular to the plane of the paper, thereby creating a cross-sectional shape with an overhang. A groove 3 is bored therein.

Among these drilling methods, by the method shown in FIG. 2a (the use of the method shown in FIG. 2b will be described later), holes are formed perpendicularly to each other on the front and back surfaces of the green sheet 1 shown in FIG. Then, a plurality of grooves 2 are bored at such depths that openings (not shown) are formed by mutual interference at the intersections (as shown in FIG. 3). In other words, the depth of the groove 2 on the front surface and the groove 2 on the back surface
By making the total depth equal to the thickness of the green sheet 1, the openings are formed at the intersections of the grooves 2.

Two green sheets 1 having grooves 2 formed in this way are stacked so that the opposing grooves 2 are perpendicular to each other (as shown in FIG. 4). In this state, the two green sheets 1 are bonded to each other by applying a pressure that does not crush the grooves 2 and sintering at a high temperature, thereby obtaining a desired boiling heat transfer surface.

When using this boiling heat transfer surface, it may be joined to a portion to be cooled, such as a heater block (not shown).

To explain the specific example of this example, first, the material is SiC ceramics (SiC and AlN).
A green sheet 1 with a thickness of 1 mm was prepared using the following: Then, using an electron beam 4 (details will be described later), grooves 2 with a width of 0.3 mm and a depth of 0.6 mm are formed on the front and back surfaces of the green sheet 1 at a pitch of 0.6 mm.
A plurality of the grooves 2 on the front and back surfaces were bored so as to be perpendicular to each other.

The processing conditions using the electron beam 4 are as follows:
It is a continuous beam of 120kV and beam current of 1mA, and the beam focus 5 is above the surface of the green sheet 1.
The converging lens current was set so that the distance was 10 mm (method according to Figure 2 a). and green sheet 1
The U-shaped groove 2 was bored by moving a moving jig (not shown) on which was placed a moving jig (not shown) at a constant speed of 10 mm/sec.

Two green sheets 1 with grooves 2 formed in this way are laminated and heated at a temperature of 2000 to 2100°C for about 1 hour while applying a surface pressure of about 3 kg/mm ² to the surface. By boiling and sintering, the desired boiling heat transfer surface could be manufactured.

In the embodiments described above, SiC ceramics were used as the ceramics because they have extremely high thermal conductivity among ceramics, and are comparable to aluminum, which is often used for heat dissipation surfaces. Furthermore, since it is chemically stable, it is extremely difficult to be corroded by seawater or chemicals.

In addition, the advantages of using ceramics in the form of green sheets are that it is relatively easy to process grooves, that they are highly flexible and can be molded to fit the shape of the cooling surface of a heater block, etc., and that when multiple sheets are laminated, they can be By sintering under pressure,
No need for a bonding process to bond each layer.
That's true.

In this example, all the grooves are U-shaped grooves 2, but only the grooves that appear on the surface when the green sheets 1 are stacked are processed by the method shown in FIG. 2b to have an overhang. A groove 3 having a cross-sectional shape may be formed. In this way, the opening of the groove 3 becomes somewhat smaller than the opening of the internal groove 2, so that bubbles of refrigerant (not shown) are retained inside the groove 3 for an appropriate amount of time. Therefore, a boiling heat transfer surface with superior heat transfer performance than one with grooves 2 formed on the surface can be obtained.

According to the embodiment described above, there are the following effects.

(1) A boiling heat transfer surface that is extremely stable against seawater and chemicals and has excellent corrosion resistance can be obtained.

(2) Grooving is performed using a high energy density beam in the green sheet state of ceramics.
Although the material is difficult to machine, it is extremely easy to process.

(3) After stacking the green sheets with grooves, the whole is sintered under pressure, so there is no joining process for joining each layer, and the whole is sintered during the sintering process. Can be joined together.

In the above embodiments, SiC ceramics were used as the ceramics, but materials other than SiC ceramics, such as alumina (AlO ₃ ) ceramics, may also be used, but the boiling heat transfer surface using SiC ceramics is As mentioned above, it has excellent properties and corrosion resistance.

Furthermore, in the above embodiments, the grooves were drilled using a high energy density beam such as an electron beam, but the grooves could also be drilled using a high energy density beam, although it is possible to use a mechanical cutter. The dimensional accuracy of the grooves drilled using the same method is extremely high, and the tool does not wear out.

Further, in the above embodiment, the boiling heat transfer surface is manufactured by laminating two ceramic thin plates, but the present invention can also be applied to the case where three or more ceramic plates are laminated, or when only one ceramic plate is laminated. Applicable. In the case of one sheet, it is sufficient to drill grooves in a thin sheet of unfired ceramic and then sinter it at high temperature, and there is no need for pressurization.

As explained in detail above, according to the present invention, on the front and back surfaces of an unfired ceramic thin plate,
After drilling multiple grooves that are perpendicular to each other and have a depth such that an opening is formed at the intersection point by mutual interference, multiple sheets of this thin plate are stacked so that the opposing grooves are perpendicular to each other. Since sintering is performed at high temperature under pressure, it is possible to provide a method for manufacturing a boiling heat transfer surface that can produce a boiling heat transfer surface with excellent corrosion resistance.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective view showing a green sheet used in the method of manufacturing a boiling heat transfer surface according to an embodiment of the present invention, and FIG. 2 is a partial perspective view showing a green sheet according to FIG. FIG. 3 is a partial sectional view showing a state in which grooves are bored by the green sheet according to FIG. 1; FIG. FIG. 4 is a partial perspective view showing a state in which two green sheets according to FIG. 3 are stacked. 1... Green sheet, 2, 3... Groove, 4... Electron beam.

Claims (1)

[Claims] 1. After drilling a plurality of grooves on the front and back surfaces of a thin plate of unfired ceramics, which are orthogonal to each other and have a depth such that an opening is formed at the intersection point by mutual interference, A method for producing a boiling heat transfer surface, which comprises laminating a plurality of these thin plates so that the opposing grooves are perpendicular to each other, and sintering the entire body at high temperature under pressure. 2. The method for manufacturing a boiling heat transfer surface according to claim 1, wherein SiC-based ceramics are used as the ceramics. 3. The method for manufacturing a boiling heat transfer surface according to claim 1, wherein the grooves are formed by machining a high energy density beam.