TWI691238B - Manufacturing method for neutron moderating material - Google Patents

Abstract

A manufacturing method for a neutron moderating material is provided, and includes: providing a metal fluoride powder, a lithium fluoride powder and an aluminum metal powder; applying a first wet mixing step to add the aluminum metal powder and the lithium fluoride powder into an organic solvent to form an aluminum-lithium fluoride slurry; applying a second wet mixing step to add the metal fluoride powder into the aluminum-lithium fluoride slurry to form a metal fluoride-aluminum-lithium fluoride slurry; drying the metal fluoride-aluminum-lithium fluoride slurry to form a metal fluoride-aluminum-lithium fluoride composite powder; and forming and densifying the metal fluoride-aluminum-lithium fluoride composite powder by a hot press process to form a fluoride-aluminum composite material. The fluoride-aluminum composite material has a relatively fine and uniform structure, a high relative density, a high purity, and a high bending strength, and thus can be used in a boron neutron capture therapy device.

Description

Manufacturing method of neutron deceleration material

The invention relates to a method for manufacturing a high-temperature fluoride ceramic and low-temperature aluminum metal composite material. The fluoride-aluminum composite material can be used as a neutron deceleration material in BNCT treatment equipment.

The principle of Boron Neutron Capture Therapy (BNCT) is briefly described as follows: First, the boron-containing drugs of pro-cancer cells need to be injected into the body of cancer patients, and the blood circulation is combined with the cancer cells, when the cancer cells gather at the concentration When the boron-containing drug is high enough, a thermal neutron beam with appropriate energy is generated from the atomic furnace or accelerator-type neutron beam source and irradiates the tumor site. Because the thermal neutron will react with the boron-containing drug, it will split into high biological damage. Ability to radiate particles, destroy the DNA structure of cancer cells, because the range of radiant particles does not exceed the diameter range of a single cancer cell, so while killing cancer cells, damage to normal cells will be minimized, thereby protecting cancer The normal tissue near the cell, so BNCT treatment is also called target and radiation therapy, especially for the treatment of head and neck cancer.

The neutron energy suitable for BNCT treatment is 1 eV to 10 keV. Therefore, the energy of high-energy neutron rays generated by an atomic furnace or an accelerator-type neutron beam source generator must be decelerated through a moderator material to reduce the energy. Suitable as thermal neutron deceleration materials are magnesium fluoride-aluminum-lithium fluoride and aluminum fluoride-aluminum-lithium fluoride and other fluoride-aluminum composite materials, in which the volume percentage of aluminum metal is about 30%, and lithium fluoride is Less than 2%. In 1997, the BNCT thermal neutron deceleration material system disclosed by Pekka Hismäki et al. in the US Patent No. 5,703,918 was aluminum fluoride-aluminum-lithium fluoride. (Hot Isostatic Pressing, HIP), as for how to carry out hot pressure equalization, it is not mentioned. However, the conventional heat equalization process needs to first fill the powder into the metal container and perform vacuum sealing (canning), and then put the metal container that has been sealed into the heat equalization device, using the gas as the pressure medium, Isotropic pressurization of the metal container completes the molding and densification of the composite material. The heat equalizing process is affected by the binding force of the metal container. The material yield is only 65~80%, and the manufacturing cost is high. Therefore, it is necessary to provide an innovative and progressive manufacturing method of fluoride-aluminum composite materials in order to increase the yield of materials and reduce manufacturing costs.

Therefore, it is necessary to provide a method for manufacturing neutron deceleration materials to solve the problems in the conventional technology.

The main object of the present invention is to provide a method for manufacturing a neutron moderating material, including the following steps: (a) providing a metal fluoride powder, a lithium fluoride powder, and a metal aluminum powder, and the purity of these powders Greater than 99.5%; (b) performing a first wet powder mixing step of the metal aluminum powder and the lithium fluoride powder in an organic carrier to form a metal aluminum-lithium fluoride slurry; (c ) Add the metal fluoride powder to the metal aluminum-lithium fluoride slurry to perform a second wet powder mixing step to form a metal fluoride-metal aluminum-lithium fluoride slurry; (d) dry the Metal fluoride-metal aluminum-lithium fluoride slurry to form a composite powder; and (e) forming and densifying the composite powder by a hot pressing process to form the metal fluoride-metal aluminum-lithium chloride One neutron moderator material.

In one embodiment of the present invention, in step (a), the metal atom of the metal fluoride is selected from alkali metals or alkaline earth metals.

In one embodiment of the present invention, in step (b), the organic carrier is selected from ethanol or isopropanol.

In one embodiment of the present invention, in step (b), the mixing time of one of the wet powder mixtures is 1 to 4 hours.

In one embodiment of the present invention, in step (c), the mixing time of one of the wet powder mixtures is 1 to 4 hours.

In one embodiment of the present invention, in step (d), the metal fluoride-metal aluminum-lithium fluoride slurry system is dried by atmospheric drying or vacuum drying to dry the slurry.

In one embodiment of the present invention, one of the drying temperatures is 80°C to 120°C.

In one embodiment of the invention, a drying time is 2 to 6 hours.

In one embodiment of the present invention, one of the vacuum drying has a vacuum degree of less than 760 torr.

In one embodiment of the present invention, in step (e), one of the temperatures of forming and densification is 550°C to 620°C.

In one embodiment of the present invention, in step (e), one of the forming and densifying pressure is 5 to 55 million pascals (MPa).

In one embodiment of the present invention, in step (e), one of the forming and densifying time is 1 to 4 hours.

As described above, the relative density of the fluoride-aluminum composite material prepared by the present invention is greater than 99.5%, the bending strength is greater than 140 MPa, and the yield rate is as high as 95%. The fluoride-aluminum composite material prepared by the invention can be used as a neutron deceleration material in BNCT treatment equipment.

S11~S15‧‧‧Step

Figure 1: Schematic flow chart of the method for manufacturing the neutron deceleration material according to the embodiment of the present invention; Figure 2: The first embodiment of the present invention is 69.5% by weight magnesium fluoride-30% aluminum-0.5% fluoride Microstructure of lithium composite material; Figure 3: The second embodiment of the present invention is a microstructure of 58.5% aluminum fluoride-40% metal aluminum-1.5% lithium fluoride composite material by weight.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, the preferred embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings, which will be described in detail below. Furthermore, the terms of direction mentioned in the present invention, such as up, down, top, bottom, front, back, left, right, inner, outer, side, surrounding, center, horizontal, horizontal, vertical, longitudinal, axial, The radial direction, the uppermost layer or the lowermost layer, etc., are only the directions referring to the attached drawings. Therefore, the directional terminology is used to illustrate and understand the present invention, not to limit the present invention.

Please refer to FIG. 1, which is a schematic flowchart of a method for manufacturing a neutron deceleration material according to an embodiment of the present invention. First, referring to step S11, metal fluoride powder, lithium fluoride powder and metal aluminum powder are provided. The purity of the powder is greater than 99.5%. The metal atoms of the metal fluoride are selected from alkali metals or alkaline earth metals.

Referring to step S12, a first wet powder mixing step is performed on the metal aluminum powder and lithium fluoride powder in an organic solvent to form a metal aluminum-lithium fluoride paste. The organic carrier is selected from One of ethanol and isopropanol. In step S12, the mixing time of the first wet powder mixing step is 1 to 4 hours.

Referring to step S13, metal fluoride powder is added to the metal aluminum-lithium fluoride slurry to perform a second wet powder mixing step to form a metal fluoride-metal aluminum-lithium fluoride slurry. In step S13, the mixing time of the second wet powder mixing step is 1 to 4 hours.

Referring to step S14, the metal fluoride-metal aluminum-lithium fluoride slurry is dried to form a metal fluoride-metal aluminum-lithium fluoride composite powder. In step S14, the drying method may be atmospheric drying or vacuum drying, wherein the drying temperature is 80°C to 120°C, the drying time is 2 to 6 hours, and the vacuum degree of vacuum drying is less than 760 torr.

Referring to step S15, the metal fluoride-metal aluminum-lithium fluoride composite powder is molded and densified in a hot pressing process. In step S15, the temperature of the molding and densification is 550°C to 620°C, the pressure of the molding and densification is 5MPa to 55MPa, and the time of the molding and densification is 1 to 4 hours.

The following examples illustrate the invention in detail, but it does not mean that the invention is limited to what is disclosed by these examples.

Example 1:

This example takes the manufacture of a magnesium fluoride-metal aluminum-lithium fluoride composite material as an example. First, according to the weight percentage of 69.5% magnesium fluoride-30% metal aluminum-0.5% lithium fluoride, magnesium fluoride powder, metal aluminum powder and lithium fluoride powder with a purity of up to 99.5% or more are provided. Next, the metal aluminum powder and lithium fluoride powder are put into an organic carrier of ethanol to perform a first wet powder mixing step to form a metal aluminum-lithium fluoride slurry, and the wet powder mixing time is 1 hour.

Then, add magnesium fluoride powder to the metal aluminum-lithium fluoride slurry to perform a second wet powder mixing step to form a magnesium fluoride-metal aluminum-lithium fluoride slurry, the wet powder mixing time is 1 hour.

Next, the magnesium fluoride-metal aluminum-lithium fluoride slurry uniformly mixed is placed in an atmospheric oven to perform a drying step, wherein the drying temperature is 120° C. and the drying time is 6 hours to obtain magnesium fluoride-metal Aluminum-lithium fluoride composite powder.

Finally, the magnesium fluoride-metal aluminum-lithium fluoride composite powder is poured into a graphite hot-pressing mold, which is hot-pressed at a hot-pressing temperature of 550°C, a hot-pressing pressure of 55 MPa, and a hot-pressing temperature of 2 hours Under the conditions, the magnesium fluoride-metal aluminum-lithium fluoride composite powder is formed and densified into a magnesium fluoride-metal aluminum-lithium fluoride composite material. Figure 2 shows the microstructure of 69.5% magnesium fluoride-30% metal aluminum-0.5% lithium fluoride composite material by weight. Obviously, the structure of the composite material is quite fine and uniform, with a relative density of 99.7%. The purity is greater than 99.5% and the three-point bending strength is 158MPa, which can be used as a neutron deceleration material.

Example 2:

This example takes the production of aluminum fluoride-metal aluminum-lithium fluoride composite material as an example. First, according to the weight percentage of 58.5% aluminum fluoride-40% metal aluminum-1.5% lithium fluoride, aluminum fluoride powder, metal aluminum powder and lithium fluoride powder with a purity of more than 99.5% are provided. Next, the metal aluminum powder and lithium fluoride powder are put into an organic carrier of isopropyl alcohol to perform a first wet powder mixing step to form a metal aluminum-lithium fluoride slurry, and the wet powder mixing time is 4 hour.

Then, add aluminum fluoride powder to the metal aluminum-lithium fluoride slurry to perform a second wet powder mixing step to form an aluminum fluoride-metal aluminum-lithium fluoride slurry, the wet powder mixing time is 4 hours.

Next, the uniformly mixed aluminum fluoride-metal aluminum-lithium fluoride slurry is placed in a vacuum oven, and a vacuum drying step is performed in a vacuum of 190 torr, where the drying temperature is 80°C and the drying time is 3 hours, that is Aluminum fluoride-metal aluminum-lithium fluoride composite powder can be obtained.

Finally, the aluminum fluoride-metal aluminum-lithium fluoride composite powder is poured into a graphite hot-pressing mold, under hot-pressing conditions, under hot-pressing conditions of hot-pressing temperature of 620°C, hot-pressing pressure of 5 MPa, and holding temperature for 3 hours , Forming and densifying aluminum fluoride-metal aluminum-lithium fluoride composite powder into aluminum fluoride-metal aluminum-lithium fluoride composite material. Figure 3 shows the microstructure of 58.5% aluminum fluoride-40% metal aluminum-1.5% lithium fluoride composite material. Obviously, the structure of the composite material is quite fine and uniform, with a relative density of 99.8%. The purity is greater than 99.5%, the three-point bending strength is 147MPa, and can be used as a neutron deceleration material.

As described above, the relative density of the fluoride-aluminum composite material prepared by the present invention is greater than 99.5%, the bending strength is greater than 140 MPa, and the yield rate is as high as 95%. The fluoride-aluminum composite material prepared by the invention can be used as a neutron deceleration material in BNCT treatment equipment.

The above-mentioned embodiments are only to illustrate the principle and efficacy of the present invention, but not to limit the present invention. Therefore, those skilled in the art can make modifications and changes to the above embodiments without departing from the invention. spirit. The scope of the rights of the present invention shall be as listed in the patent application scope described later.

S11~S15‧‧‧Step

Claims (11)

A method for manufacturing a neutron retarding material includes the following steps: (a) providing a metal fluoride powder, a lithium fluoride powder, and a metal aluminum powder, the purity of these powders is greater than 99.5%; (b ) Perform a first wet powder mixing step of the metal aluminum powder and the lithium fluoride powder in an organic carrier to form a metal aluminum-lithium fluoride slurry; (c) add the metal fluoride powder Performing a second wet powder mixing step in the metal aluminum-lithium fluoride slurry to form a metal fluoride-metal aluminum-lithium fluoride slurry; (d) drying the metal fluoride-metal aluminum- Lithium fluoride slurry to form a composite powder; and (e) forming and densifying the composite powder by a hot pressing process to form a neutron moderator material of the metal fluoride-metal aluminum-lithium chloride, The metal fluoride powder is selected from magnesium fluoride powder or aluminum fluoride powder. The manufacturing method as described in item 1 of the patent application scope, wherein in step (b), the organic carrier is selected from ethanol or isopropanol. The manufacturing method as described in item 1 of the patent application scope, wherein in step (b), the mixing time of one of the wet powder mixtures is 1 to 4 hours. The manufacturing method as described in item 1 of the patent application scope, wherein in step (c), the mixing time of one of the wet powder mixtures is 1 to 4 hours. The manufacturing method as described in item 1 of the patent application scope, wherein in step (d), the metal fluoride-metal aluminum-lithium fluoride slurry system is dried by air drying or vacuum drying method to dry the slurry. The manufacturing method as described in item 5 of the patent application scope, in which drying The degree system is 80°C to 120°C. The manufacturing method as described in item 5 of the patent application scope, wherein a drying time is 2 to 6 hours. The manufacturing method as described in item 5 of the patent application scope, wherein one of the vacuum drying has a vacuum degree of less than 760 torr. The manufacturing method as described in item 1 of the patent application scope, wherein in step (e), one of the temperatures of molding and densification is 550°C to 620°C. The manufacturing method as described in item 1 of the patent application scope, wherein in step (e), one of the forming and densifying pressure is 5 to 55 million pascals (MPa). The manufacturing method as described in item 1 of the patent application scope, wherein in step (e), one of the forming and densifying time is 1 to 4 hours.

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