Combined coating protection structure for thrust chamber body and preparation method of combined coating protection structure

Abstract

The invention provides a combined coating protection structure of a thrust chamber body and a preparation method of the combined coating protection structure. The thrust chamber body comprises a combustion chamber section and a spray pipe extension section. A base body of the combustion chamber section is niobium-tungsten alloy, and molybdenum silicide coatings are prepared on the inner and outer surfaces for protection; a base body of the extension section of the spray pipe is niobium-tungsten or niobium-hafnium alloy, and slurry sintering coatings are prepared on the inner and outer surfaces for protection; the combustion chamber section and the spray pipe extending section are welded through high-energy beams. A combined coating protection structure is adopted, and the problem of long service life of a small-size attitude and orbit control thrust chamber body is solved; after the molybdenum silicide coating is prepared at the combustion chamber section and the combined coating is prepared at the body part, the parallel part of the product is selected for sectioning inspection, the thickness of the dissimilar coating in the lap joint area can be measured, and the technical problem of verification of the production quality of the coating in the lap joint area of the combined coating is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid rocket engines, and in particular to a thrust chamber body combined coating protection structure and a preparation method thereof. Background Art

[0002] The thrust chamber of a space attitude and orbit control liquid rocket engine adopts a method of coating a high-temperature anti-oxidation coating on the surface of a material with excellent high-temperature mechanical properties to resist long-term erosion and oxidation by high-temperature combustion gases. Among them, niobium alloys and slurry sintering coatings are the most widely used material systems, and their preparation is basically not limited by the size of the body, and the technical solutions are mature and reliable. The construction of space stations and large-capacity and large-mass satellite platforms has greatly extended the life of the thrust chamber of space attitude and orbit control liquid rocket engines. Traditional slurry sintering coatings can no longer meet the requirements. Molybdenum silicide coatings have become one of the effective solutions due to their higher melting point, self-healing, and high density. However, the preparation process is complicated and is limited by the size and technical capabilities of the infiltration furnace equipment, so it cannot be used to prepare large-sized thrust chamber bodies.

[0003] Molybdenum silicide coating belongs to the category of high-temperature anti-oxidation silicide coating. Its preparation method is a two-step process of arc deposition and silicide infiltration. Arc deposition of molybdenum layer is to use arc discharge to evaporate molybdenum ions from molybdenum target material and deposit them on the surface of workpiece under vacuum environment to form a molybdenum layer. Silicidation infiltration is to bury the workpiece after the molybdenum layer is deposited in infiltration powder (silicon powder, etc.). In vacuum environment and at a certain temperature, a chemical reaction occurs between silicon powder and substrate to form a molybdenum silicide coating.

[0004] There is a certain multiple relationship between the thickness of the molybdenum silicide coating formed after the silicide treatment and the thickness of the molybdenum layer deposited by the arc, which is called the silicide multiple, but the silicide multiple fluctuates in a large range. Once the molybdenum layer is not completely silicided and residues are left during the silicide process, the life of the body will be reduced; and if the thickness of the molybdenum silicide coating is insufficient, the life of the body to resist gas erosion will also be reduced. Therefore, it is very important to judge the quality of the molybdenum layer silicide and measure the coating thickness.

[0005] Through searching the prior art patent documents, it was found that the patent document with publication number CN116623135A discloses a body structure of an attitude and orbit control thrust chamber with coating protection and a preparation method thereof, including a short body and an extension section, an ion sputtering coating is arranged on the outer wall of the short body, and a slurry sintering coating is arranged on the outer wall of the extension section. The attitude and orbit control thrust chamber is a large-size and large-area ratio attitude and orbit control thrust chamber with a thrust level greater than 1000N. An embodiment also provides a preparation method of the above-mentioned body structure of the attitude and orbit control thrust chamber with coating protection, but since it is impossible to prepare samples of coatings with accurate thickness in the overlapping area for calibration, it is impossible to measure the thickness of multiple overlapping coatings separately by a conventional eddy current thickness gauge, and the measurement error of the mechanical measurement method is large. The invention does not provide a solution for judging the preparation quality of the coating covering the two coating areas. Summary of the invention

[0006] In view of the defects in the prior art, an object of the present invention is to provide a thrust chamber body combined coating protection structure and a preparation method thereof.

[0007] According to the thrust chamber body combined coating protection structure provided by the present invention, the thrust chamber body includes a combustion chamber section and a nozzle extension section, and the coating protection structure includes:

[0008] A molybdenum silicide coating is applied to the inner and outer surfaces of the combustion chamber section;

[0009] The slurry sintered coating is applied to the inner and outer surfaces of the nozzle extension section.

[0010] Preferably, the matrix of the combustion chamber segment is a niobium-tungsten alloy.

[0011] Preferably, the substrate of the nozzle extension section is a niobium-tungsten alloy or a niobium-hafnium alloy.

[0012] Preferably, the combustion chamber section and the nozzle extension section are welded by high-energy beam welding.

[0013] Preferably, a slurry sintering coating is prepared in the welding area between the combustion chamber section and the nozzle extension section, and the slurry sintering coating covers the inner and outer surfaces of the combustion chamber section outlet section area.

[0014] Preferably, the vacuum thrust level generated by the thrust chamber used in the thrust chamber body is not higher than 800N, and the length of the combustion chamber section is not greater than 160mm.

[0015] Preferably, the position of the weld at the connecting end surface of the combustion chamber section and the nozzle extension section is perpendicular to the symmetry axis of the thrust chamber;

[0016] When the thrust chamber is working, the temperature of the outer wall at the welding position is not higher than 1200° C., and the high-energy beam welding includes electron beam welding or laser welding.

[0017] Preferably, the slurry sintered coating is a Si-Cr-Ti or Si-Cr-Ti-Hf silicide coating.

[0018] Preferably, the diameter of the inner wall outlet of the base of the combustion chamber section is the same as the diameter of the inner wall inlet of the base of the nozzle extension section;

[0019] The wall thickness of the base outlet of the combustion chamber section is 0.4 to 0.8 mm thicker than the wall thickness of the base inlet of the nozzle extension section.

[0020] The method for preparing the thrust chamber body combined coating protection structure provided by the present invention is used to prepare the thrust chamber body combined coating protection structure, comprising the following steps:

[0021] Step S1: using niobium-tungsten alloy rods to machine and produce a base body of the combustion chamber section;

[0022] Step S2: preparing a molybdenum silicide coating on the inner and outer surfaces of the substrate of the combustion chamber section by arc deposition and silicide infiltration;

[0023] Step S3: randomly selecting a base product of the combustion chamber section as a product parallel part, cutting it symmetrically along the axis and performing metallographic inspection;

[0024] If there is no molybdenum layer remaining in any part of the combustion chamber section, step S4 is executed; if there is a molybdenum layer remaining in the combustion chamber section, the entire batch of products is re-siliconized and infiltrated until there is no molybdenum layer remaining in any part of the combustion chamber section;

[0025] Step S4: removing the molybdenum silicide coating on the inner and outer surfaces of the combustion chamber section outlet section;

[0026] Step S5: using niobium-tungsten alloy sheet or niobium-hafnium alloy sheet to spin-form a substrate of the nozzle extension section, and connecting it to the combustion chamber section by high-energy beam welding;

[0027] Step S6: pickling the inner and outer surfaces of the welding area and the nozzle extension section, and then preparing a slurry sintering coating on the inner and outer surfaces of the welding area and the nozzle extension section, wherein the slurry sintering coating covers the combustion chamber section outlet section area;

[0028] Step S7: randomly select a product as a parallel part of the product, cut it symmetrically along the axis, and perform metallographic inspection to check whether the slurry sintering coating meets the specified thickness requirement;

[0029] If the slurry sintering coating meets the specified thickness requirement, the preparation is completed; if the slurry sintering coating does not meet the specified thickness requirement, the slurry sintering coating is prepared again for the entire batch of products until the slurry sintering coating meets the specified thickness requirement.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The combustion chamber section of the present invention is prepared with a molybdenum silicide coating with a higher melting point, self-healing and high density, and the nozzle extension section is prepared with a slurry sintering coating. For small-sized thrust chambers with a thrust level not exceeding 800N, a combined coating protection structure for the body is provided, which solves the problem of long-life operation of the body of small-sized attitude and orbit control thrust chambers.

[0032] 2. After preparing the molybdenum silicide coating in the combustion chamber section, the present invention selects parallel pieces of the product, cuts them symmetrically into four parts along the axis for metallographic inspection, and verifies the process quality of the silicide encapsulation of the batch products. After completing the preparation of the combined coating on the body, parallel pieces of the product are selected for cutting and inspection, and the thickness of the heterogeneous coatings in the overlapping area can be measured, thereby judging the coating production quality in the overlapping area of ​​the combined coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0034] Figure 1 It is a structural schematic diagram of the combined coating protection structure of the thrust chamber body in the present invention;

[0035] Figure 2 for Figure 1 A partial enlarged schematic diagram of part A in the middle.

[0036] The figure shows:

[0037] Combustion chamber section 1 Base body 21 of nozzle extension section

[0038] Combustion chamber section substrate 11 Slurry sintered coating 22

[0039] Molybdenum silicide coating 12 Welding position 3

[0040] Nozzle extension 2 DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0042] The present invention discloses a combined coating protection structure for a thrust chamber body and a preparation method thereof. By adopting a molybdenum silicide coating and a slurry sintering coating to form a combined coating protection structure, the problem of long-life operation of a small-sized attitude and orbit control thrust chamber body is solved. By preparing the molybdenum silicide coating on the combustion chamber section and the combined coating on the body, the product parallel parts are randomly selected for cutting and inspection, thereby solving the technical problem of coating production quality verification in the overlap area of ​​the combined coating.

[0043] Example 1

[0044] This embodiment provides a thrust chamber body combined coating protection structure, such as Figure 1 , Figure 2 As shown, the thrust chamber body includes a combustion chamber section 1 and a nozzle extension section 2, and the coating protection structure includes a molybdenum silicide coating 12, which is applied to the inner and outer surfaces of the combustion chamber section 1, and a slurry sintered coating 22, which is applied to the inner and outer surfaces of the nozzle extension section 2. Among them, the substrate 11 of the combustion chamber section is a niobium tungsten alloy, and the substrate 21 of the nozzle extension section is a niobium tungsten alloy or a niobium hafnium alloy, and the combustion chamber section 1 and the nozzle extension section 2 are welded by high-energy beam welding.

[0045] The welding area between the combustion chamber section 1 and the nozzle extension section 2 is prepared with a slurry sintering coating 22, and the slurry sintering coating 22 covers the inner and outer surfaces of the outlet section area of ​​the combustion chamber section 1. The vacuum thrust level generated by the thrust chamber used in the thrust chamber body is not higher than 800N, and the length of the combustion chamber section 1 is not greater than 160mm. The end face weld position 3 connecting the combustion chamber section 1 and the nozzle extension section 2 is perpendicular to the symmetry axis of the thrust chamber; when the thrust chamber is working, the outer wall of the weld position 3 is subjected to a temperature not higher than 1200℃, and the high-energy beam welding includes electron beam welding or laser welding. The slurry sintering coating 22 is a Si-Cr-Ti system or Si-Cr-Ti-Hf system silicide coating. The outlet diameter of the inner wall of the substrate 11 of the combustion chamber section is the same as the inlet diameter of the inner wall of the substrate 21 of the nozzle extension section; the outlet wall thickness of the substrate 11 of the combustion chamber section is 0.4 to 0.8mm thicker than the inlet wall thickness of the substrate 21 of the nozzle extension section.

[0046] The method for preparing the above thrust chamber body combined coating protection structure comprises the following steps:

[0047] Step S1: using niobium-tungsten alloy rods to machine and produce a base 11 of the combustion chamber section;

[0048] Step S2: preparing a molybdenum silicide coating 12 on the inner and outer surfaces of the substrate 11 of the combustion chamber section by arc deposition and silicide infiltration;

[0049] Step S3: randomly selecting a base body 11 product of the combustion chamber section as a product parallel piece, cutting it symmetrically along the axis and performing metallographic inspection;

[0050] If there is no molybdenum layer remaining in all parts of the combustion chamber segment 1, step S4 is performed; if there is a molybdenum layer remaining in the combustion chamber segment 1, the entire batch of products is re-siliconized and infiltrated until there is no molybdenum layer remaining in all parts of the combustion chamber segment 1;

[0051] Step S4: removing the molybdenum silicide coating 12 on the inner and outer surfaces of the outlet section of the combustion chamber section 1;

[0052] Step S5: using a niobium-tungsten alloy sheet or a niobium-hafnium alloy sheet to spin-form a substrate 21 of the nozzle extension section, and connecting it to the combustion chamber section 1 by high-energy beam welding;

[0053] Step S6: pickling the inner and outer surfaces of the welding area and the nozzle extension section 2, and then preparing a slurry sintering coating 22 on the inner and outer surfaces of the welding area and the nozzle extension section 2, and the slurry sintering coating 22 covers the outlet section area of ​​the combustion chamber section 1;

[0054] Step S7: randomly select a product as a product parallel piece, cut it symmetrically along the axis and perform metallographic inspection to check whether the slurry sintered coating 22 meets the specified thickness requirement;

[0055] If the slurry sintered coating 22 meets the specified thickness requirement, the preparation is completed; if the slurry sintered coating 22 does not meet the specified thickness requirement, the slurry sintered coating 22 is prepared again for the entire batch of products until the slurry sintered coating 22 meets the specified thickness requirement.

[0056] Example 2

[0057] This embodiment is a preferred embodiment of embodiment 1, and provides a thrust chamber body combined coating protection structure, including: a combustion chamber section 1 and a nozzle extension section 2; the substrate 11 of the combustion chamber section is a niobium tungsten alloy, and the inner and outer surfaces are both prepared with molybdenum silicide coatings for protection; the substrate 21 of the nozzle extension section is a niobium tungsten alloy, and the inner and outer surfaces are both prepared with slurry sintering coatings 22 for protection; high-energy beam welding is used between the combustion chamber section 1 and the nozzle extension section 2;

[0058] The method for preparing the above thrust chamber body combined coating protection structure comprises the following steps:

[0059] Step S1: using niobium-tungsten alloy rods to machine and produce a base 11 of the combustion chamber section;

[0060] Step S2: preparing a molybdenum silicide coating 12 on the inner and outer surfaces of the substrate 11 of the combustion chamber section by arc deposition and silicide infiltration;

[0061] Step S3: randomly select a product as a product parallel piece, cut it into four parts symmetrically along the axis for metallographic inspection, and require that there is no molybdenum layer remaining in all parts of the combustion chamber section 1;

[0062] Step S4: Remove the molybdenum silicide coating 12 on the inner and outer surfaces of the combustion chamber section 1 from the outlet to 15 mm upstream by lathe processing to expose the niobium tungsten alloy substrate, and allow a thin layer of the molybdenum silicide coating 12 to remain. Figure 2 As shown;

[0063] Step S5: using niobium-tungsten alloy sheet to spin-form the substrate 21 of the nozzle extension section, and connecting it to the combustion chamber section 1 by high-energy beam welding;

[0064] Step S6: pickling the inner and outer surfaces of the welding area and the nozzle extension section 2, and then preparing a slurry sintering coating 22 on the inner and outer surfaces of the welding area and the nozzle extension section 2, and the slurry sintering coating 22 covers the outlet section area of ​​the combustion chamber section 1;

[0065] Step S7: A product is randomly selected as a product parallel part, and it is cut into four parts symmetrically along the axis for metallographic inspection. The slurry sintering coating 22 is required to meet the specified thickness requirement, wherein the thickness of the slurry sintering coating 22 is 200μm, and the thickness of the residual molybdenum silicide coating 12 is less than 50μm. It is verified by the test rod that the coating's high-temperature oxidation resistance life and thermal shock resistance times can meet the use requirements. The thrust chambers of the same batch have successfully passed the high-altitude simulated thermal test and reached the expected working life, which is more than twice the life of the body using only the slurry sintering coating 22.

[0066] Among them, the vacuum thrust level generated by the thrust chamber is 200N, and the length of the combustion chamber section 1 is 160mm. The end face weld position 3 connecting the combustion chamber section 1 and the nozzle extension section 2 is perpendicular to the symmetry axis of the thrust chamber; when the thrust chamber is working, the outer wall of the weld position 3 is subjected to a measured temperature of 1100°C; the high-energy beam welding is electron beam welding. The slurry sintering coating 22 is a Si-Cr-Ti-Hf series silicide coating. The outlet diameter of the inner wall of the substrate 11 of the combustion chamber section is the same as the inlet diameter of the inner wall of the substrate 21 of the nozzle extension section. The outlet wall thickness of the substrate 11 of the combustion chamber section is 0.8mm thicker than the inlet wall thickness of the substrate 21 of the nozzle extension section, which is more conducive to the effective penetration depth of the flat butt weld and increases the butt fault tolerance margin.

[0067] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0068] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A thrust chamber body combined coating protection structure, characterized in that: The thrust chamber body comprises a combustion chamber section (1) and a nozzle extension section (2), and the coating protection structure comprises: A molybdenum silicide coating (12) is applied to the inner and outer surfaces of the combustion chamber section (1); The slurry sintered coating (22) is applied to the inner and outer surfaces of the nozzle extension section (2).

2. The thrust chamber body combined coating protection structure according to claim 1 is characterized in that: The base (11) of the combustion chamber section is a niobium-tungsten alloy.

3. The thrust chamber body combined coating protection structure according to claim 1, characterized in that: The substrate (21) of the nozzle extension section is a niobium-tungsten alloy or a niobium-hafnium alloy.

4. The thrust chamber body combined coating protection structure according to claim 1, characterized in that: The combustion chamber section (1) and the nozzle extension section (2) are welded by high-energy beam welding.

5. The thrust chamber body combined coating protection structure according to claim 4 is characterized in that: The welding area between the combustion chamber section (1) and the nozzle extension section (2) is prepared with a slurry sintering coating (22), and the slurry sintering coating (22) covers the inner and outer surfaces of the outlet section area of ​​the combustion chamber section (1).

6. The thrust chamber body combined coating protection structure according to claim 1, characterized in that: The vacuum thrust level generated by the thrust chamber used in the thrust chamber body is not higher than 800N, and the length of the combustion chamber section (1) is not greater than 160mm.

7. The thrust chamber body combined coating protection structure according to claim 4, characterized in that: The position of the weld seam (3) at the end surface where the combustion chamber section (1) and the nozzle extension section (2) are connected is perpendicular to the symmetry axis of the thrust chamber; When the thrust chamber is working, the outer wall of the weld position (3) is subjected to a temperature not higher than 1200° C., and the high-energy beam welding includes electron beam welding or laser welding.

8. The thrust chamber body combined coating protection structure according to claim 1, characterized in that: The slurry sintered coating (22) is a Si-Cr-Ti series or Si-Cr-Ti-Hf series silicide coating.

9. The thrust chamber body combined coating protection structure according to claim 1, characterized in that: The outlet diameter of the inner wall of the base body (11) of the combustion chamber section is the same as the inlet diameter of the inner wall of the base body (21) of the nozzle extension section; The wall thickness of the outlet of the base body (11) of the combustion chamber section is 0.4 to 0.8 mm thicker than the wall thickness of the inlet of the base body (21) of the nozzle extension section.

10. A method for preparing a combined coating protection structure for a thrust chamber body, characterized in that: The method for preparing the thrust chamber body combined coating protection structure according to any one of claims 1 to 9 comprises the following steps: Step S1: using niobium-tungsten alloy rods to mechanically process and produce a base body (11) of a combustion chamber section; Step S2: preparing a molybdenum silicide coating (12) on the inner and outer surfaces of the substrate (11) of the combustion chamber section by arc deposition and silicide infiltration; Step S3: randomly selecting a base body (11) product of the combustion chamber section as a parallel product, cutting it symmetrically along the axis and performing metallographic inspection; If no molybdenum layer remains in any part of the combustion chamber section (1), step S4 is performed; if a molybdenum layer remains in the combustion chamber section (1), the entire batch of products is re-siliconized and infiltrated until no molybdenum layer remains in any part of the combustion chamber section (1); Step S4: removing the molybdenum silicide coating (12) on the inner and outer surfaces of the outlet section of the combustion chamber section (1); Step S5: using a niobium-tungsten alloy plate or a niobium-hafnium alloy plate to spin-form a substrate (21) of the nozzle extension section, and connecting it to the combustion chamber section (1) by high-energy beam welding; Step S6: pickling the inner and outer surfaces of the welding area and the nozzle extension section (2), and then preparing a slurry sintering coating (22) on the inner and outer surfaces of the welding area and the nozzle extension section (2), wherein the slurry sintering coating (22) covers the outlet section area of ​​the combustion chamber section (1); Step S7: randomly selecting a product as a parallel product, cutting it symmetrically along the axis and performing metallographic inspection to check whether the slurry sintered coating (22) meets the specified thickness requirement; If the slurry sintered coating (22) meets the specified thickness requirement, the preparation is completed; If the slurry sintered coating (22) does not meet the specified thickness requirement, the slurry sintered coating (22) is prepared again for the entire batch of products until the slurry sintered coating (22) meets the specified thickness requirement.

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