JPH0350902B2 - - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to the structure and manufacturing method of a rocket combustion chamber having a groove-structured cooling wall, particularly a rocket combustion chamber with an improved outer cylinder.

BACKGROUND ART A rocket combustion chamber having a conventional groove structure cooling wall has a combustion chamber cylinder 1 and an outer cylinder integrally formed on the outside of the inner cylinder 1, as shown in a partially cutaway cross-sectional view in FIG. It consists of 2. A groove structure cooling wall having a large number of grooves 1a is formed on the outer circumferential surface of the inner cylinder 1 in order to circulate a cooling liquid such as liquid hydrogen.
By the way, in this type of rocket combustion chamber,
The outer cylinder 2 is generally made of a material with high mechanical strength in order to withstand extremely high combustion pressure and the pressure within the cooling groove 1a. On the other hand, the inner cylinder 1 is made of a material with excellent thermal conductivity, such as oxygen-free copper, and therefore has relatively low strength. As a result, the stiffness of the entire combustion chamber is considerably increased by the strength of the outer cylinder 2, and therefore all the stress generated by the operation of the rocket combustion chamber with the groove cooling wall is transferred to the weakest strength of the combustion chamber cylinder. There is a phenomenon of concentration on 1. This phenomenon is particularly noticeable in rocket engines that are intended to be used many times, such as rocket engines used in space shuttles, and the material constituting the inner cylinder 1 suffers from low-cycle thermal fatigue. There was a problem in that the bonding interface between the inner cylinder 1 and the outer cylinder 2 peeled off, or the grooves 1a were connected to adjacent grooves 1a, greatly impairing the cooling effect.

Therefore, in the United States, where rocket engines using this type of combustion chamber have entered the practical stage, research is being actively conducted to reduce the rigidity of the outer cylinder 2. For example, as shown in the partially cutaway cross-sectional view of Fig. 9, the outer cylinder 2, which had a structure made of a single Ni electroformed layer, which was implemented at NASA's Lewis Research Institute, was replaced with a Cu, which has less rigidity than Ni. Attempts have been made to replace the electroformed layer 3 with a laminated structure of a glass fiber or carbon graphite layer 4. However, in this method, the airtightness of the Cu electroformed layer 3 is not good, so the Cu
The thickness of the layer 3 could not be made very thin, so the rigidity could not be reduced as much as expected, and the reliability of airtightness was low.
Therefore, there were problems such as poor durability.

Problems to be Solved by the Invention Therefore, an object of the present invention is to realize a rocket engine in which the rigidity of the outer cylinder is reduced while maintaining the required mechanical strength, and which is therefore highly durable. An object of the present invention is to provide a rocket combustion chamber and a method for manufacturing the same.

Means for Solving the Constituent Problems of the Invention In summary, the present invention provides a rocket combustion chamber comprising an inner cylinder having a groove structure cooling wall on the outer circumferential surface and an outer cylinder provided around the inner cylinder. , the outer cylinder is
A porous tube comprising a metal plating layer formed on the outer periphery of an inner cylinder, a porous metal layer formed on the inner cylinder side, and a reinforcing cylinder formed on the outside of the porous metal layer. A step of preparing an inner cylinder which is a rocket combustion chamber having a hard layer on the outer shell and having a groove structure cooling wall on the outer peripheral surface, a step of forming a metal plating layer on the outer periphery of the inner cylinder, and a step of forming the metal plating layer on the outer periphery of the inner cylinder. This method of manufacturing a rocket combustion chamber includes the steps of forming a porous metal layer around the layer and forming a reinforcing tube outside the porous metal layer.

Next, an example of the structure of the rocket combustion chamber of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of a rocket combustion chamber of the present invention, and FIG. 2 is an external perspective view thereof. As is clear from FIG. 1, in this rocket combustion chamber, a metal plating layer of, for example, Cu or Ag is applied to the outer periphery of the inner cylinder 11, which has a cooling wall with a groove structure consisting of a large number of cooling grooves 11a formed on the outer peripheral surface. 15 is formed, and has a structure in which a porous metal layer 16 and a reinforcing tube 17 are provided on the outside of the plating layer 15. That is, in the rocket combustion chamber of this invention,
The outer cylinder has metal plating 15 formed on the outer periphery of the inner cylinder 11 and a porous metal layer 1 formed on the inner cylinder 11 side.
6, and a reinforcing cylinder 17 formed outside the porous layer 16. However, the porous metal layer 16 is similar to the metal plating layer 15 and the inner cylinder 1.
1 and is not joined to the reinforcing tube 17. By the way, porous metal layer 1
6 may be composed of, for example, a foamed metal or a foamed metal whose voids are filled with powder such as Cu or Ag. Since the porous metal layer 16 is configured in this way, its elastic modulus is extremely small, and therefore, all stress generated in the inner cylinder 11 is absorbed by the porous metal layer 16. Note that the reinforcing tube 17 may be made of any material as long as it has mechanical strength to withstand hoop stress generated by combustion pressure.

Note that the metal plating layer 15 shown in FIG.
is provided to ensure airtightness since the porous metal layer 16 has voids,
Although it can be formed by plating with Cu or Ag as described above, Cu plating is preferable from the viewpoint of heat resistance.

Although not particularly shown in FIG. 1, in order to completely thermally isolate the gap between the porous metal layer 16 and the reinforcing tube 17, a resin treatment such as a fluororesin is applied to provide heat insulation. A layer may also be provided, in which case thermal stresses are reduced and the life of the rocket combustion chamber can be extended.

In addition, in FIG. 1, in terms of mechanical strength, the inner cylinder 11, metal plating layer 15, and porous metal layer 16 are of an integral structure, and the reinforcing cylinder 17 is structurally separated. I would like to point out that it is preferable. This is because with this configuration, all the stress generated in the inner cylinder 11 as described above can be absorbed by the porous metal layer 16.

Next, a method for manufacturing a rocket combustion chamber having the structure shown in FIG. 1 will be explained with reference to FIGS. 3 to 7. First, as in the conventional case, an inner cylinder 11 is prepared in which a large number of cooling grooves 11a are formed on the outer peripheral surface and a groove structure cooling wall is provided (FIG. 3). Next, by immersing the inner cylinder 11 in a molten low melting point metal bath, for example, a clay metal bath, the groove 11a is filled with the low melting point metal 18, as shown in FIG. When filling the low melting point metal 18, it is preferable to fill it under pressure in order to prevent casting defects such as voids occurring in the metal. Next, the outer periphery of the filled low melting point metal 18 is machined into a predetermined shape, that is, so that it is flush with the outer peripheral wall 11b of the inner cylinder 11 (see FIG. 4), and then sealed with, for example, Cu. By applying the
A metal plating layer 15 is formed as shown in the figure.

Next, a layer with a porosity of 90, for example, is placed around the plating layer 15.
% or more of the foamed metal layer is formed and placed in a mold 21 as shown in FIG. Next, mold 2
1, the porous metal layer 16 is formed by vibration filling a metal powder such as electrolytic copper powder, and then performing hydrostatic pressing (CIP).
form.

Next, the low melting point metal 18 filled in the cooling groove
is eluted from the groove portion 11a by heating in a non-oxidizing atmosphere, and then sintered in a sintering furnace. After the structure thus formed is machined into a predetermined shape, a reinforcing cylinder 17 is inserted, thereby obtaining the rocket combustion chamber of the present invention as shown in FIG.

Next, a method for manufacturing the porous metal layer 16, which is a characteristic structure of the present invention, will be explained in more detail. The porous metal layer 16 can be manufactured using foamed metal as described above, and can also be constructed from a liquid phase sintered layer using a multi-component mixed powder.

First, regarding the former case of using foamed metal, in order to obtain a porous metal layer formed by molding and sintering, as described above, the Cu plating layer 1 is
A foamed metal having a porosity of 90% or more is placed in the gap between the foamed metal 5 and the mold 21, and the voids of the foamed metal are filled with copper powder, followed by isostatic pressing. Foamed metal can be constructed from a variety of metallic materials, such as copper, silver and nickel. As for the metal powder to be filled into the voids of the metal foam, in addition to pure copper powder, mixed powder or copper alloy powder in which a small amount of silver or tin is added to copper can also be used. moreover,
It is also possible to use metal powders other than copper-based, for example metal powders mainly made of silver, nickel, stainless steel, iron, etc. Due to the sintering process, the foamed metal will form a strong framework in the porous metal layer, and at the same time the porous metal layer 16 will exhibit its inherent low elastic modulus.

Next, in the case of a porous metal layer consisting of a liquid phase sintered layer using a multi-component mixed powder, after filling the cooling groove 11a of the inner cylinder 11 shown in FIG. 4), its outer periphery and rubber mold 21
A mixed powder of electrolytic copper powder and tin powder, copper-
After filling with tin alloy powder, mixed powder of electrolytic copper powder and silver powder, or copper-silver alloy powder, hydrostatic pressing is performed. Thereafter, as in the case of using the foamed metal described above, the low melting point metal 18 is eluted and removed, and then a sintering treatment is performed. In this case, the sintering conditions are set so that the copper-tin or copper-silver mixed powder, or their respective alloy powders undergo liquid phase sintering. As a result, tin or silver becomes a solid solution with copper, strengthening the copper structure, and at the same time, creating fine spherical residual voids uniformly distributed within the sintered layer, which has a low elastic modulus, and copper itself It is possible to form a porous metal layer 16 having a mechanical strength exceeding that of .

Example 1 A combustion chamber cylinder made of oxygen-free copper (OFHC) having a groove structure cooling wall was immersed in a molten low-melting metal bath with a melting point of 100°C, and was heated under a pressure of 4 to 5 Kgf/cm ² in an N ₂ atmosphere. The mixture was placed under pressure and solidified. Next, the excess low melting point metal was removed by machining. It was confirmed that the low melting point metal part did not have any casting defects such as cavities.

Next, copper plating was applied to the outer peripheral surface to a thickness of about 50 μm. Furthermore, Ni foam metal was attached to the outer periphery of the copper plating layer to a thickness of about 10 mm, and placed in a rubber mold. In a rubber mold, the voids of the metal foam were filled with electrolytic copper powder having a particle size of 44 μm or less, and hydrostatic pressing was performed under a pressure of 2.0 tf/cm ² .

Next, the obtained inner cylinder was placed in an Ar gas atmosphere for 200 min.
The low melting point metals were eluted by holding at a temperature of 30 minutes. Furthermore, in a hydrogen atmosphere,
Sintering treatment was performed at a temperature of 750°C for 1 hour. After the sintered body thus obtained is machined into a predetermined shape, the outside of the sintered layer is treated with fluororesin or other resin to form a heat insulating layer, and the outside is further coated with stainless steel or Inconel-based high-grade material. A reinforced outer cylinder made of tension material was inserted. Therefore, the inner cylinder of the combustion chamber and the porous outer shell are separated from the reinforcing cylinder, so that the inner cylinder and the porous metal layer are configured to be able to expand and contract independently of the outer cylinder. Therefore, it was possible to obtain a rocket combustion chamber that can withstand combustion pressure without impairing the low elastic modulus of the porous metal layer.

Effects of the Invention As described above, according to the present invention, the outer cylinder includes a metal plating layer formed on the outer periphery of the inner cylinder, a porous metal layer formed on the inner cylinder side, and the porous metal layer. Since it consists of a reinforcing tube formed on the outside of the outer tube, it is possible to reduce the rigidity of the outer tube while maintaining mechanical strength, thereby dramatically improving the durability of the rocket engine. It becomes possible to realize a rocket combustion chamber.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of a specific structure of a rocket combustion chamber according to the present invention. FIG. 2 is an external perspective view of the combustion chamber shown in FIG. 1. FIGS. 3 to 7 are partially cutaway perspective views showing the process of manufacturing the combustion chamber shown in FIGS. 1 and 2, with FIG. 3 showing the shape of the inner cylinder, and FIG. 5 shows a state in which the inner cylinder is filled with a low melting point metal, FIG. 5 shows a state in which a metal plating layer is formed, and FIG. 6 shows a state in which a porous metal layer is arranged in the mold. FIG. 7 shows the state in which the reinforcing tube is covered. FIG. 8 is a partially cutaway sectional view showing an example of a conventional rocket combustion chamber. FIG. 9 is a partially cutaway sectional view showing another example of a conventional rocket combustion chamber. In the figure, 11 is an inner cylinder, 11a is a groove, 15 is a metal plating tank, 16 is a porous metal layer, 17 is a reinforcing cylinder, and 18 is a low melting point metal.

Claims (1)

[Scope of Claims] 1. A rocket combustion chamber including an inner cylinder having a groove structure cooling wall on the outer peripheral surface and an outer cylinder provided around the inner cylinder, wherein the outer cylinder is an outer cylinder of the inner cylinder. A porous layer comprising a metal plating layer formed on the inner cylinder side, a porous metal layer formed on the inner cylinder side, and a reinforcing cylinder formed on the outside of the porous metal layer. Rocket combustion chamber in the outer shell. 2. A rocket combustion chamber having a porous layer in an outer shell according to claim 1, wherein a heat insulating layer is provided between the porous metal layer and the reinforcing cylinder. 3. A rocket combustion chamber having a porous layer in an outer shell according to claim 1 or 2, wherein the porous metal layer is a foamed metal filled with metal powder. 4. A step of preparing an inner cylinder having a groove structure cooling wall on the outer peripheral surface, a step of forming a metal plating layer on the outer periphery of the inner cylinder, and a step of forming a porous metal layer around the metal plating layer. A method for manufacturing a rocket combustion chamber having a porous layer as an outer shell, the method comprising: forming a reinforcing tube outside the porous metal layer. 5. The porous metal layer is formed by forming a foamed metal layer around the metal plating layer, then vibration-filling with metal powder, and isostatic pressing. A method for manufacturing a rocket combustion chamber having a porous layer in the outer shell. 6. The method of removing the porous layer according to claim 4 or 5, further comprising the step of forming a heat insulating layer around the outer periphery of the porous metal layer, following the step of forming the porous metal layer. A method for manufacturing a rocket combustion chamber in a shell.