RU2792095C1 - Method for manufacturing multilayer parts from a reactive material - Google Patents

Abstract

FIELD: manufacturing multilayer materials.

SUBSTANCE: methods for manufacturing multilayer materials for protection against various types of radiation that can be used for the manufacture of layered products of arbitrary profile. Technical problem: development of an effective method for manufacturing multilayer parts from a reactive material that shields various types of radiation and is operable under operating conditions. In contrast to the background method for obtaining pressed strengthened parts from a reactive material, according to which the products are manufactured from a reactive material by molding, heat treatment of products from a reactive material is carried out; blanks of formed large-sized parts of a specific standard size and profile by pressing under pressure of at least 3 t/cm² at room temperature from a powder reactive material, followed by placing a package of individual layers in the mold matrix to form volumetric parts, maintaining a thermal gap between the inner walls of the matrix and the outer surface of the assembled package, then supplement the mold with a punch and perform pressing with a pressure of at least 0.3 t/cm² preheated in the temperature range of 500-510°С of a package with maintaining the package under pressure when cooled up to 150-200°C and followed by natural cooling of the finished product demolded to room temperature. It is possible for small-sized parts to press the package with a pressure of at least 0.3 t/cm² when the package is heated to temperatures of 390-410°C and maintaining the heated package under a pressure of at least 0.05 t/cm² when cooled to temperatures of 150-200°C followed by natural cooling of the finished product demolded to room temperature.

EFFECT: provision of conditions for obtaining a multilayer neutron-shielding material of an arbitrary profile with strength sufficient for subsequent machining.

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Description

The present invention relates to the field of technologies for obtaining multilayer materials for protection against various types of radiation and can be used for the manufacture of layered products of arbitrary profile.

From the prior art, a method for manufacturing a multilayer material is known (RF patent No. 2013187, IPC B22F 07/04, publ. 05/28/1994), according to which an intermediate layer of powdered metal powder with the property of diffusion interaction with the base material with particle size 50-400 microns, which is baked to the base and subjected to pressing.

However, this method does not provide for obtaining a material for protection against radiation.

A known method for producing pressed hardened parts from a reactive material (RF patent No. 2764537, IPC B22F 3/12, publ. material, for which they take a powdered reactive material in the form of lithium hydride of natural isotopic composition, mold parts of a given profile by pressing at a specific pressing load of at least 3 t/cm ² at room temperature, then conduct subsequent heat treatment of the pressed parts when placed in a sealed container , which is evacuated to a pressure of 140-170 Pa and the temperature is raised to 500-600°C with a heating rate of not more than 10°C/min.

The heat treatment process is carried out for 1-5 hours, followed by cooling and holding in a container for at least 3 hours, while maintaining a given degree of vacuum in a sealed container within 140-170 Pa.

However, the known method does not provide for obtaining a multilayer neutron shielding material of arbitrary profile with the required mechanical strength.

The relevance of the problem being solved is due to the demand for technologies for manufacturing radiation protection parts in the form of monolithic large-sized blocks of complex configuration with the required strength and density, as well as multilayer parts from chemically homogeneous materials with different isotopic compositions without the use of adhesive bonding.

The task of the authors of the invention is to develop an effective method for manufacturing multilayer parts from a reactive material that shields various types of radiation and is operable under operating conditions.

The technical result provided by the proposed method, in contrast to the prototype, is to provide conditions for obtaining a multilayer neutron-shielding material of arbitrary profile with strength sufficient for subsequent machining.

The specified task and the new technical result are ensured by the fact that, unlike the prototype, for the manufacture of multilayer parts from a reactive material, pre-production of complex-shaped parts of a given size and profile is carried out by pressing under a pressure of at least 3 t/cm ² at room temperature from powder reactive material, followed by placing a package of individual layers in a mold matrix for forming complex-shaped (volumetric) parts, maintaining a thermal gap between the inner walls of the matrix and the outer surface of the assembled package, then supplementing the mold with a punch and pressing with a pressure of at least 0.3 t/cm ² preheated in the temperature range of 500-510°C package with keeping the package under pressure while cooling to 150-200°C and followed by natural cooling of the finished product extracted from the mold to room temperature.

For small-sized parts, blanks of parts of a given size and profile are manufactured by pressing under a pressure of at least 3 t/cm ² at room temperature from a powder reactive material, followed by placing a package of individual layers in a mold matrix to form complex-shaped (volumetric) parts, with maintaining a thermal gap between the inner walls of the matrix and the outer surface of the assembled package, then the mold is supplemented with a punch and the package is pressed with a pressure of at least 0.3 t / cm ² when the package is heated to temperatures of 390-410 ° C and the heated package is kept under pressure less than 0.05 t/cm ² when cooled to temperatures of 150-200°C, followed by natural cooling of the finished product extracted from the mold to room temperature.

The proposed method is explained as follows.

In FIG. 1 shows the layout of pressed blanks of complex-shaped parts in a restrictive mold, where 1 is the base; 2 - lower punch; 3 - matrix; 4 - upper punch; 5 - samples; 6 - channels for thermocouples.

In FIG. 2 is an image of a multilayer part made of reactive material after fabrication.

In FIG. 3 is an image of a multilayer part made of reactive material after machining.

In FIG. 4 shows a view of a laboratory setup for the manufacture of multilayer small-sized samples, where 1 is the base; 2 - racks; 3 - bottom plate; 4 top plate; 5 - samples; 6 - punches; 7 - dynamometer; 8 - intermediate plate; 9 - electric split oven.

In FIG. 5 shows the layout of small-sized samples in the sleeve, where 1 sleeve, 2 - punches, 3 - samples, 4 - estimated gap (0.1 mm).

The inventive method is implemented as follows.

Initially, blanks of 5 complex-profile parts of a given size and profile are made by pressing a floor with a pressure of at least 3 t/cm ² at room temperature from a powder chemically active material, followed by placing a package of individual layers in a matrix 3 with a base 1 of a mold to form complex-profile (volumetric ) parts, with maintaining a thermal gap between the inner walls of the matrix and the outer surface of the assembled package, then the mold is supplemented with a punch 4 and pressing ^is carried out with a pressure of at least 0.3 t/cm under pressure during cooling to 150-200°C and with subsequent natural cooling of the finished product extracted from the mold to room temperature, the assembly temperature is controlled by thermocouples placed in the channels 6 of the mold.

To confirm the effectiveness of the proposed method, a sample of six layers was mechanically processed, each of which had a diameter of 70 mm and a height of 20 mm, made by the proposed method from lithium hydride of natural isotopic composition. The image of a multilayer sample immediately after manufacturing (Fig. 2) and after mechanical (milling and turning) processing (Fig. 3) indicates that the required strength has been achieved. The finished product also recorded the absence of hair-like cracks, which were present in the original blanks-layers as a result of the stressed state of the material during pressing and pressing out.

Thus, when using the proposed method, a new technical result is provided, namely, unlike the prototype, providing conditions for obtaining a multilayer neutron-shielding material of an arbitrary profile with strength sufficient for subsequent machining.

The possibility of industrial implementation of the invention is confirmed by the following examples of specific implementation.

Example 1

Cylindrical parts with a diameter of 70 mm and a height of 20 mm from lithium hydride of natural isotopic composition are made by cold pressing to size. Pressing parts is carried out at a specific pressing load of 3 t/cm ² and room temperature (20±5)°C. Sampling is carried out in an argon atmosphere with an absolute humidity of not more than 0.2 g/m ² ; backfilling of the sample, pressing, pressing out, determination of mass-geometric parameters - in the air atmosphere at a relative humidity of not more than 50% with a minimum residence time of the sample in a humid environment.

A frill of 6 parts connected along the end surfaces is placed in a restrictive mold according to the scheme (Fig. 1). The working surfaces of the mold are pre-treated with a water-alcohol solution of colloidal graphite lubricant and thoroughly dried for half an hour. The thermocouples are fixed in the channels of the mold so that the sensitive elements of the thermocouples touch the surface of the mold.

The assembly is heated in a muffle furnace to a temperature of 520°C. Upon reaching the required temperature, the mold is removed from the oven, transferred under a hydraulic press in 2-3 minutes and exerted a force of 11540 kgf (~0.3 t/cm ² ). The pressure is maintained during the cooling of the assembly to a temperature of 200°C at an average cooling rate of 2.5°/min, then the pressure is removed from the parts, after the assembly is cooled to a temperature of ~80°C, the mold is disassembled, the sintered multilayer part is placed in the medium argon absolute humidity not more than 0.2 g/m ³ .

Example 2. Under the conditions of example 1, but for small-sized samples, the proposed method is implemented on a laboratory installation (Fig. 4), which is a base 1 with vertical posts 2. The following are installed on the posts: the bottom plate 3, which transmits force to the dynamometer 7 and the top plate 4, moving by a reducer. The assembly of specimens 5 through punches 6 is clamped between the upper and lower plates, which makes it possible to measure the magnitude of the force applied to the end surface of the specimens. A detachable electric furnace 9 is installed on the intermediate plate 8. Special means ensure minimal heat losses during heating of the furnace. To control and regulate the heating temperature, a thermocouple is attached near the contact boundary of the samples.

In the cylindrical sleeve 1 (Fig. 5) is placed an assembly of two samples 3 with a diameter of 25 mm and a height of 20 mm from lithium hydride of natural isotopic composition, sintered on the end surface. Punches 2 are installed on top and bottom of the assembly.

The oven is heated to 470°C in 30 minutes, which allows the assembly to be heated to a temperature of 260°C. Hold the samples for 60 minutes at an oven temperature of 470°C until the assembly temperature reaches 396°C.

From the moment the heating starts, the force on the assembly is applied no higher than 1480 kgf (~30 N/mm ² ) - due to thermal expansion, the pressure of the samples on the tooling is constantly growing. After turning off the oven, during cooling, the assembly force is maintained at least 230 kgf (~4.7 N/mm ² ). Upon reaching the assembly temperature of 150°C, the load from the samples is removed.

As shown by experimental studies of the proposed method, when using the conditions and the proposed materials for a multilayer sample, the following is provided:

- the average shear strength of the butt joint according to the test results of five samples was σ _shear =(9.2±3.6) N/mm ² at a loading speed of 20 mm/min and a test temperature of 23.4°C. In shear tests, failure occurs along the material, and not along the joint, which indicates a sufficient strength of the joint;

- preservation of a cylindrical shape with a change in diameter - by (0.04 ... 0.06) mm, height - by (0.4 ... 0.5) mm down;

- increase in density by 1.3%;

- decrease in the content of the main substance by no more than (0.8 ... 1.0) wt. %.

Claims (2)

1. A method for the manufacture of multilayer parts from a reactive material, including the manufacture of individual layers in the form of complex-shaped parts, the formation of a package of individual layers, subsequent heating and pressing of the package to obtain a multilayer finished product, characterized in that in order to ensure molding conditions without air access and aggressive environment, as well as the possibility of obtaining a finished product of increased strength, sufficient for subsequent machining and to obtain a finished product that is operable under mechanical loads, blanks of complex-profile parts of a given size and profile are pre-made by pressing under a pressure of at least 3 t/cm ² at room temperature. temperature from a powder reactive material, followed by placement of a package of individual layers in the mold matrix for the formation of complex-shaped three-dimensional parts, maintaining a thermal gap between the inner walls of the matrix and the outer surface of the assembled package, then the mold is supplemented with a punch and pressing is carried out with a pressure of at least 0.3 t/cm ² of the package preheated in the temperature range of 500-510°C while maintaining the package under pressure while cooling to 150-200°C and followed by natural cooling of the finished product extracted from the mold to room temperature. 2. The method according to p. 1, characterized in that the package is pressed with a pressure of at least 0.3 t/cm ² when the package is heated to 390-410 ° C and the package is kept at a pressure of at least 0.05 t/cm ² during cooling under pressure to temperatures of 150-200°C, followed by natural cooling of the finished product extracted from the mold to room temperature.

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