A method for preparing a seven-hole multilayer propellant by end-face spraying

Abstract

This invention discloses a method for preparing a seven-hole multilayer propellant by end-face spraying, applicable to the end-face sealing of multilayer propellants. The invention employs a honeycomb mold to constrain the propellant columns, enabling the orderly arrangement of the seven-hole multilayer propellant. The larger diameter of the inner holes in the honeycomb mold facilitates filling. A solvent-based swelling and sealing technique ensures a tight fit between the outer wall of the seven-hole multilayer propellant and the inner wall of the honeycomb mold, protecting the outer wall. Using a spraying liquid made of the same material as the outer layer of the seven-hole multilayer propellant forms a protective layer with the same composition as the outer layer on the end face, significantly improving the combustion pyrolysis properties of the propellant. This invention solves the problem of only being able to prepare seven-hole multilayer propellants by end-face spraying, providing a technical means for preparing seven-hole multilayer propellants by end-face spraying.

Description

Technical Field

[0001] This invention relates to the field of propellant technology, and more particularly to surface treatment processes for multilayer propellants, specifically to a preparation method for end-face treatment of seven-hole multilayer propellants, which enables spraying coating on their end faces. Background Technology

[0002] Multilayer propellants consist of inner and outer layers, prepared through co-extrusion. Currently, they are mainly tubular and sheet-like multilayer propellants. Because the bonding between their layers is much tighter than that of coating or desensitizing processes, they possess higher density, better stability, and excellent combustion escalation properties, making them widely used in small-caliber weapons. With the increasing demands for energy density from large-caliber, high-power artillery, existing coating and desensitizing processes cannot meet the high energy density requirements. Seven-hole multilayer propellants are one such technical solution. However, as the propellant diameter increases, the end-face area of ​​the seven-hole multilayer propellant increases rapidly, leading to a continuous decrease in combustion escalation properties. Therefore, the end-face treatment of seven-hole multilayer propellants becomes particularly important. The main surface treatment methods for propellants are: (1) using a rotating drum and spray gun, in which the propellant is placed in a rotating drum and the coating liquid is sprayed onto the surface of the propellant while the drum is rotating continuously, so that the surface of the propellant is covered with a coating layer. This method is obviously not suitable for the requirement that the end face of the seven-hole multilayer propellant can only be sprayed; (2) using a powder mixing method, in which the propellant is added to a pot containing the coating material and stirred and rotated, so that the surface of the propellant is covered with a coating layer. This method is also not suitable for the requirement that the end face of the seven-hole multilayer propellant can only be sprayed. Therefore, the existing preparation methods are all designed for full coating of the propellant and cannot meet the requirement that only the end face of the seven-hole multilayer propellant can be coated.

[0003] Based on the technical data currently available, there is no method for preparing propellant that allows for the application of coating only the propellant end face without coating the propellant column itself. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a preparation method that uses mold constraint, solvent swelling and drying techniques to spray coating only the end faces of a seven-hole multilayer propellant.

[0005] The preparation method provided by this invention comprises the following steps:

[0006] (1) Calculate the swelling coefficient based on the seven-hole multilayer propellant formulation.

[0007]

[0008] r is the swelling coefficient of the seven-hole multilayer propellant.w r is the swelling coefficient of the outer layer of the seven-hole multilayer propellant. n D is the swelling coefficient of the inner layer of the seven-hole multilayer propellant, and e is the outer diameter of the seven-hole multilayer propellant. w The thickness of the outer layer of the seven-hole multi-layer propellant;

[0009] (2) Calculate the dimensions of the honeycomb mold and inner holes based on the dimensions and swelling coefficient of the seven-hole multilayer propellant.

[0010] H k <L

[0011] D < D k <r×D

[0012] H k L is the depth of the inner hole, and the thickness of the mold is the same as the depth of the inner hole. D is the length of the seven-hole multi-layer propellant. k The diameter of the inner hole;

[0013] (3) The honeycomb mold is disc-shaped and has multiple internal holes;

[0014] (4) Place the seven-hole multilayer propellant in the inner hole of the honeycomb mold;

[0015] (5) Applying solvent in small amounts and multiple times allows the seven-hole multilayer propellant to swell and adhere completely to the inner wall of the hole.

[0016] (6) Use a blade to trim the protruding seven-hole multi-layer propellant end faces at both ends of the honeycomb mold;

[0017] (7) The same material as the outer layer of the seven-hole multilayer propellant is used to spray the two ends of the honeycomb mold, and the spray thickness is [missing information].

[0018] P h =r×e w

[0019] P h The thickness of the coating;

[0020] (8) Place the honeycomb mold in an oven to dry it. After the solvent evaporates, take out the seven-hole multilayer propellant sample with end face spraying.

[0021] Therefore, by using a honeycomb mold to constrain the propellant column and a solvent to swell the seven-hole multilayer propellant, the outer wall of the propellant can be completely protected and not contaminated during the spraying process, thus obtaining a sample in which only the end face of the seven-hole multilayer propellant is sprayed.

[0022] The present invention provides a method for preparing a seven-hole multilayer propellant by end-face spraying, which has the following advantages compared with the prior art:

[0023] (1) The use of a honeycomb mold to constrain the propellant column enables the orderly arrangement of the seven-hole multi-layer propellant, and the large diameter of the inner hole of the honeycomb mold makes it easier to fill the seven-hole multi-layer propellant. Compared with the prior art, the orderly arrangement of the seven-hole multi-layer propellant can be achieved through the reasonable design of the honeycomb mold, providing a technical means for the efficient spraying of the propellant end face.

[0024] (2) The technique of using solvent to swell and seal the propellant can tightly fit the outer wall of the seven-hole multilayer propellant with the wall of the inner hole of the honeycomb mold, thus protecting the outer wall of the propellant. Moreover, fluctuations in the outer diameter of the propellant within a certain range do not affect the sealing effect. Compared with the existing technology, solvent swelling and sealing does not introduce other impurities and is applicable to a wider range of propellant diameters, which can significantly improve the yield of propellant.

[0025] (3) By using a spraying liquid made of the same material as the outer layer of the seven-hole multilayer propellant, a protective layer with the same composition as the outer layer can be formed on the end face of the seven-hole multilayer propellant. This gives the seven-hole multilayer propellant a completely encapsulated morphology, which can significantly improve the combustion escalation of the seven-hole multilayer propellant. Compared with the prior art, the end face of the seven-hole multilayer propellant has better compatibility with the spraying material, and the resulting seven-hole multilayer propellant has higher combustion escalation.

[0026] Therefore, this invention solves the problem that the preparation of seven-hole multilayer propellants can only be done by end-face spraying, and provides a technical means for preparing seven-hole multilayer propellants by end-face spraying. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a honeycomb mold.

[0028] Figure 2 yes Figure 1 Sectional view along direction A.

[0029] Figure 3 This is a flowchart of the preparation process for end-face spraying of a seven-hole multilayer propellant. Detailed Implementation

[0030] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] like Figure 1 , Figure 2As shown, the inner layer of the seven-hole multilayer propellant 3 consists of 70% nitrocellulose with a nitrogen content of 12.6% and 30% RDX; the outer layer consists of 60% nitrocellulose with a nitrogen content of 12.6% and 40% nitroguanidine. The seven-hole multilayer propellant 3 has an outer diameter of 10 mm, a length of 18 mm, an inner hole diameter of 0.4 mm, and an outer layer thickness of 0.5 mm. The honeycomb mold 2 contains nineteen inner holes 1.

[0032] according to Figure 3 The preparation steps for the end-face spraying of the seven-hole multilayer propellant shown are as follows:

[0033] (1) The swelling coefficient of the seven-hole multilayer propellant 3 was calculated based on its formulation. The calculated swelling coefficient of the inner layer of the seven-hole multilayer propellant 3 was 1.3, and the swelling coefficient of the outer layer 5 was 1.2.

[0034]

[0035] The swelling coefficient of the seven-hole multilayer propellant 3 was calculated to be 1.23.

[0036] (2) Calculate the dimensions of the honeycomb mold 2 and the inner hole 1 based on the dimensions and swelling coefficient of the seven-hole multilayer propellant 3.

[0037] H k <18

[0038] 10 < D k <1.23×10

[0039] Take H k The depth is 16mm, meaning the depth of the inner hole 1 and the thickness of the honeycomb mold 2 are both 16mm. Let D be... k The diameter is 11mm, meaning the diameter of the inner hole 1 of the honeycomb mold 2 is 11mm;

[0040] (3) The honeycomb mold 2 is disc-shaped with dimensions of Ф85mm×16mm and has nineteen internal holes 1;

[0041] (4) Place the seven-hole multilayer propellant 3 into the inner hole 1 of the honeycomb mold 2;

[0042] (5) Acetone is used as the solvent. The solvent is sprayed in small amounts and multiple times so that the seven-hole multilayer propellant 3 swells and adheres completely to the inner wall of the hole.

[0043] (6) Use a blade to trim the end faces of the seven-hole multi-layer propellant 3 protruding at both ends of the honeycomb mold 2 so that the end faces are flush and there are no protruding seven-hole multi-layer propellant 3.

[0044] (7) Using the same material as the outer layer of the seven-hole multilayer propellant 3, spray the two ends of the honeycomb mold 2 with a coating thickness of [missing information].

[0045] P h =r×e w =1.23 × 0.5

[0046] The calculated coating thickness is 0.62 mm;

[0047] (8) Place the honeycomb mold 2 in an oven and set the oven temperature to 85°C for drying. Observe it every 8 hours. After the solvent evaporates, take out the seven-hole multilayer propellant 3 sample with end face spraying.

[0048] The above steps yield a seven-hole multilayer propellant 3 with only the outer layer material sprayed on the end face. Since the outer wall of the seven-hole multilayer propellant 3 remains unchanged, the resulting seven-hole multilayer propellant 3 has a dense structure with the outer layer fully covered, and has high density and good combustion gradation properties.

Claims

1. A method for the end face spray coating of seven-perforated multilayer propellant, characterized in that The steps are as follows: (1) Calculate the swelling coefficient based on the seven-hole multilayer propellant formulation. r is the swelling coefficient of the seven-hole multilayer propellant. The swelling coefficient of the outer layer of the seven-hole multilayer propellant. The swelling coefficient of the inner layer of the seven-hole multilayer propellant. The outer diameter of the seven-hole multi-layer propellant. The thickness of the outer layer of the seven-hole multi-layer propellant; (2) Calculate the dimensions of the honeycomb mold and inner holes based on the dimensions and swelling coefficient of the seven-hole multilayer propellant. The depth of the inner hole is given, and the thickness of the mold is the same as the depth of the inner hole. The length of the seven-hole multi-layer propellant. The diameter of the inner hole; (3) The honeycomb mold is disc-shaped and has multiple internal holes; (4) Place the seven-hole multilayer propellant in the inner hole of the honeycomb mold; (5) Applying solvent in small amounts and multiple times allows the seven-hole multilayer propellant to swell and adhere completely to the inner wall of the hole; (6) Use a blade to trim the protruding seven-hole multi-layer propellant end faces at both ends of the honeycomb mold; (7) The same material as the outer layer of the seven-hole multilayer propellant is used to spray the two ends of the honeycomb mold, and the thickness of the spray is [missing information]. The thickness of the coating; (8) Place the honeycomb mold in an oven to dry it. After the solvent evaporates, take out the seven-hole multilayer propellant sample with end face spraying.

2. The method for preparing a seven-hole multilayer propellant by end-face spraying according to claim 1, characterized in that, The dimensions of the honeycomb mold and its inner holes are calculated based on the size of the seven-hole multilayer propellant and its swelling coefficient. The honeycomb mold has a size of Φ85mm×16mm and N (N=1, 2, 3...) inner holes with a size of Φ11mm×16mm.

Images