Tungsten-based alloy composite shielding material and preparation method thereof

Abstract

The invention discloses a tungsten-based alloy composite shielding material and a preparation method thereof, and relates to the technical field of shielding materials, and the tungsten-based alloy composite shielding material is formed by processing tungsten powder, iron powder and nickel powder. The preparation method comprises the following steps that tungsten powder, nickel powder and iron powder are mixed according to the dosage proportion and then subjected to ball milling, and mixed powder is obtained; the mixed powder is subjected to granulation and compression molding, and a material blank is obtained; the material blank is degreased and then sintered, and a plate is obtained; and carrying out heat treatment and machining on the plate to obtain the tungsten-based alloy composite shielding material. The tungsten-based alloy composite shielding material not only has a good shielding effect on irradiation neutrons, but also has good mechanical properties, and meanwhile, under the condition that the shielding effect is equivalent, the volume of the tungsten-based alloy composite shielding material can be reduced by more than 15% compared with the volume of lead; and the pollution of the shielding material to the environment and the adverse effect on the health of a user can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of shielding materials, and in particular to a tungsten-based alloy composite shielding material and a preparation method thereof. Background Art

[0002] A nuclear reactor and its circuits are a powerful and complex mixed radiation field. Nuclear fission (or fusion) produces various radiation rays, such as neutrons of different energy levels, gamma rays, secondary gamma rays and other charged particles and high-energy rays. In order to effectively shield the reactor and its circuits under normal operating conditions and accident conditions, and to protect the safety of personnel and the environment, my country widely uses lead materials for reactor radiation shielding.

[0003] The main advantages of lead as a radiation shielding material are: high density, relatively cheap price, and easy preparation. However, lead is a toxic heavy metal that is harmful to human body and environmental organisms. The storage, processing, transportation, and use of lead will produce lead dust or lead vapor, thus polluting the environment. In addition, lead has a "weak absorption zone" for rays with energy between 40keV and 80keV, which is not ideal for X-ray shielding.

[0004] Although lead has been effectively used in the field of radiation shielding for many years, considering the toxicity of lead and the risk of environmental pollution, reducing the use of lead is the general trend of the development direction of shielding materials. With the closure of factories without post-processing capabilities, the production price and post-processing price of lead will increase significantly, and its price advantage will be greatly reduced. In addition, lead has a low melting point. As a radiation shielding material, lead must be welded and cut. During welding and cutting, the high temperature will cause lead to vaporize, which will cause great pollution to personnel and the working environment. Summary of the invention

[0005] Based on the problem that the currently prepared lead-based shielding materials have poor shielding performance, the purpose of the present invention is to provide a tungsten-based alloy composite shielding material and a preparation method and application thereof. The tungsten-based alloy composite shielding material not only has a good shielding effect on irradiated neutrons, but also has good mechanical properties. At the same time, under the condition of equivalent shielding effect, the volume of the tungsten-based alloy composite shielding material can be reduced by more than 15% compared with the volume of lead.

[0006] The present invention is achieved through the following technical solutions:

[0007] In a first aspect, the present application provides a tungsten-based alloy composite shielding material, wherein the tungsten-based alloy composite shielding material is processed from tungsten powder, iron powder and nickel powder;

[0008] The raw material components of the tungsten-based alloy composite shielding material include 65% to 97% tungsten powder in terms of mass percentage, and the remainder is nickel powder and iron powder, wherein the mass fraction ratio of nickel powder to iron powder is 7:3.

[0009] Furthermore, the raw material components of the tungsten-based alloy composite shielding material include, by mass percentage, 85% of tungsten powder and 15% of a mixture of nickel powder and iron powder, wherein the mass fraction ratio of nickel powder to iron powder is 7:3.

[0010] Furthermore, the raw material components of the tungsten-based alloy composite shielding material include, by mass percentage, 90% of tungsten powder and 10% of a mixture of nickel powder and iron powder, wherein the mass fraction ratio of nickel powder to iron powder is 7:3.

[0011] Furthermore, the raw material components of the tungsten-based alloy composite shielding material include, by mass percentage, 95% of tungsten powder and 5% of a mixture of nickel powder and iron powder, wherein the mass fraction ratio of nickel powder to iron powder is 7:3.

[0012] Furthermore, the purity of the tungsten powder is greater than 99.95%, the purity of the nickel powder is greater than 99.5%, and the purity of the iron powder is greater than 99.5%.

[0013] In a second aspect, the present application provides a method for preparing a tungsten-based alloy composite shielding material, comprising the following steps:

[0014] Tungsten powder, nickel powder and iron powder are mixed according to the usage ratio and then ball-milled to obtain mixed powder;

[0015] Granulating and pressing the mixed powder to obtain a material body;

[0016] After degreasing the material embryo, sintering is performed to obtain a plate;

[0017] The plate is subjected to heat treatment and machining to obtain a tungsten-based alloy composite shielding material.

[0018] The ball milling adopts a drum ball mill with a rotation frequency of 10 rpm for 48 hours, and the ratio between the grinding balls and the total mass of the tungsten powder, nickel powder and iron powder is 2:1.

[0019] The pressing process is to press the mixed powder particles formed by granulation into a material body, and the pressed material body is a block with a size of 150 mm×150 mm×5 mm.

[0020] Among them, the material body is degreased in an intermittent degreasing furnace with a maximum degreasing temperature of 1100°C and a degreasing time of 15 hours.

[0021] The sintering is carried out in a continuous sintering furnace, the atmosphere is hydrogen, the sintering temperature is 1350° C. to 1550° C., and the sintering time is 1 to 2 hours.

[0022] Furthermore, the tungsten powder, nickel powder and iron powder are pretreated respectively before being mixed and ball-milled to improve the powder morphology and enhance the surface activity of the powder.

[0023] Furthermore, sieving granulation is selected during granulation; paraffin system is selected as the molding agent during compression molding; and hydrogen is used as the degreasing atmosphere.

[0024] Among them, during degreasing, the flow rate of hydrogen is 1m 3 / h~3m 3 / h.

[0025] The process temperature during heat treatment is 1000°C and the vacuum degree is <10Pa.

[0026] Furthermore, the addition amount of the paraffin system is 0.5% to 1.5% of the total mass of the raw materials.

[0027] Furthermore, the density of the prepared tungsten-based alloy composite shielding material is 13.32 g / cm 3 ~18.44g / cm 3 .

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] (1) The tungsten-based alloy composite shielding material of the present invention uses tungsten as the main shielding material, and is matched with nickel powder and iron powder that are radiation-resistant and have a relatively large specific gravity, which can avoid the shielding material from polluting the environment and causing adverse effects on the health of users; through the selection of shielding material components, it is achieved that when the shielding effect is equivalent, the volume of the tungsten-based alloy composite shielding material of the present invention can be reduced by more than 15% compared with the volume of lead.

[0030] (2) The tungsten-based alloy composite shielding material of the present invention has been shown through radiation resistance tests: when the average neutron injection of the irradiation is 4.28×10 18 n / cm 2 (E>1.0MeV), the tungsten-based alloy composite shielding material sample still has good mechanical properties.

[0031] (3) The tungsten-based alloy composite shielding material of the present invention is environmentally friendly and pollution-free, has excellent toughness and structural adaptability, can be used in the fields of pipeline and equipment protection, radioactive material storage, medical treatment and other radiation protection during nuclear power overhaul, and does not produce harmful substances. It can be used in a wider range of places than lead.

[0032] (4) The present invention uses tungsten as the main material, which not only makes the prepared tungsten-based alloy composite shielding material have good radiation shielding performance and mechanical properties, but also makes the tungsten-based alloy composite material non-toxic and has low fertilizer processing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0034] Figure 1 is a diagram of a gamma shielding calculation model in an embodiment of the present invention;

[0035] Figure 2 This is a SEM morphology comparison diagram of tungsten powder before and after pretreatment in an embodiment of the present invention;

[0036] Figure 3 A schematic diagram of a shielding test in an embodiment of the present invention;

[0037] Figure 4 1 is an appearance diagram of the tensile specimen in Example 1 of the present invention, wherein (a) is the specimen before irradiation; (b) is the specimen after irradiation;

[0038] Figure 5 1 is an appearance diagram of a tensile specimen in Example 2 of the present invention, wherein (a) is the specimen before irradiation; (b) is the specimen after irradiation;

[0039] Figure 6 : This is an appearance diagram of the tensile specimen in Example 3 of the present invention, wherein (a) is the specimen before irradiation; (b) is the specimen after irradiation;

[0040] Figure 7 : is a tensile curve diagram of the tensile specimen in Example 1 of the present invention; wherein (a) is the specimen before irradiation; (b) is the specimen after irradiation;

[0041] Figure 8 : is a tensile curve diagram of the tensile specimen in Example 2 of the present invention; wherein (a) is the specimen before irradiation; (b) is the specimen after irradiation;

[0042] Fig. 9 3 is a tensile curve diagram of the tensile specimen in Example 3 of the present invention; wherein (a) is the specimen before irradiation; and (b) is the specimen after irradiation. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0044] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Example 1

[0046] This embodiment provides a method for preparing a tungsten-based alloy composite shielding material, which is prepared by the following steps:

[0047] S1. Pre-treat tungsten powder, nickel powder and iron powder respectively. The SEM morphology of tungsten powder before and after pre-treatment is shown in the figure below: Figure 2 shown.

[0048] S2. The tungsten powder, nickel powder and iron powder obtained after the pretreatment are mixed according to the usage ratio and then ball-milled to obtain a mixed powder, wherein the mass fraction of the tungsten powder used is 85%, the mass fraction of the nickel powder is 10.5%, and the mass fraction of the iron powder is 4.5%.

[0049] The ball milling adopts a drum ball mill, the ball milling time is 48 hours, and the mass of the grinding balls is twice the total mass of the tungsten powder, nickel powder and iron powder.

[0050] S3, granulating the mixed powder by sieving.

[0051] S4. Use a 300-ton hydraulic press to press the mixed powder particles formed by granulation into a material blank.

[0052] During the pressing and molding, a paraffin system is selected as a molding agent, and the addition amount of the paraffin system is 1% of the total mass of tungsten powder, nickel powder and iron powder.

[0053] S5. Degrease the material body at a maximum temperature of 1100° C., and then sinter it in a hydrogen atmosphere at about 1450° C. for 2 hours to obtain a sample plate.

[0054] Among them, during degreasing, the flow rate of hydrogen is 1m 3 / h~3m 3 / h.

[0055] S6. The obtained plate is subjected to heat treatment and machining to obtain a tungsten-based alloy composite shielding material having a size of 150 mm×150 mm×5 mm.

[0056] The process temperature during heat treatment is 1000°C and the vacuum degree is <10Pa.

[0057] The shielding performance and radiation resistance performance of the tungsten-based alloy composite shielding material (numbered: WP-6) prepared by the preparation method in Example 1 were tested.

[0058] 1. Test the shielding performance of tungsten-based alloy composite shielding materials.

[0059] The shielding capability of tungsten-based alloy composite shielding materials is measured by dosimeters (such as Figure 3 The dosimeter measurement range is 1×10 -5 Gy / h~1×10 -1 Gy / h, using 137 The shielding performance of tungsten-based alloy composite shielding materials was tested by Cs radiation source, and the γ shielding calculation model was as follows: Figure 1 As shown, for the convenience of comparison with lead, the shielding test results of the tungsten-based alloy composite shielding material samples are in the form of lead equivalent (mmPb). 137 The Cs radiation source shielding test result is 6.37 mmPb (see Table 1).

[0060] 2. Test the radiation resistance of tungsten-based alloy composite shielding materials.

[0061] The tungsten-based alloy composite shielding material was processed into in-pile irradiation samples, and an out-of-pile cold test was carried out before irradiation. The in-pile irradiation test was completed in the Minjiang Test Reactor (MJTR), and the irradiation effect analysis of the samples was completed. The inspection contents included: appearance inspection, dimensional measurement, tensile test, etc.

[0062] After testing, the density of the 5mm thick tungsten-based alloy composite material prepared is 15.81g / cm 3 The average neutron injection of the sample is 4.47×10 18 n / cm 2 (E>1.0MeV), the appearance inspection before and after irradiation is as follows Figure 4 As shown in the figure, the tensile test results are as follows Figure 7 As shown in the figure, the maximum dimensional change before and after irradiation is 0.06mm (see Table 2). After irradiation, the tensile specimens all broke within the gauge length. The average yield strength of the specimens was 627MPa, the average tensile strength was 930MPa, and the average elongation after fracture was 26.83%. Compared with the unirradiated specimens, the yield strength of the specimens increased by 113MPa, the tensile strength increased by 40MPa, and the elongation decreased by about 6.96%.

[0063] Example 2

[0064] This embodiment provides a method for preparing a tungsten-based alloy composite shielding material. The difference from Embodiment 1 is that the mass fraction of tungsten powder used in this embodiment is 90%, the mass fraction of nickel powder is 7%, and the mass fraction of iron powder is 3%. The preparation is carried out by the following steps:

[0065] S1. Pre-treat tungsten powder, nickel powder and iron powder.

[0066] S2. The tungsten powder, nickel powder and iron powder obtained after the pretreatment are mixed according to the usage ratio and then ball-milled to obtain a mixed powder, wherein the mass fraction of the tungsten powder used is 90%, the mass fraction of the nickel powder is 7%, and the mass fraction of the iron powder is 3%.

[0067] The ball milling adopts a drum ball mill, the ball milling time is 48 hours, and the mass of the grinding balls is twice the total mass of the tungsten powder, nickel powder and iron powder.

[0068] S3, granulating the mixed powder by sieving.

[0069] S4. Use a 300-ton hydraulic press to press the mixed powder particles formed by granulation into a material blank.

[0070] During the pressing and molding, a paraffin system is selected as a molding agent, and the addition amount of the paraffin system is 1% of the total mass of tungsten powder, nickel powder and iron powder.

[0071] S5. Degrease the material body at a maximum temperature of 1100° C., and then sinter it in a hydrogen atmosphere at about 1500° C. for 2 hours to obtain a sample plate.

[0072] Among them, during degreasing, the flow rate of hydrogen is 1m 3 / h~3m 3 / h.

[0073] S6. The obtained plate is subjected to heat treatment and machining to obtain a tungsten-based alloy composite shielding material having a size of 150 mm×150 mm×5 mm.

[0074] The process temperature during heat treatment is 1000°C and the vacuum degree is <10Pa.

[0075] The shielding performance and radiation resistance performance of the tungsten-based alloy composite shielding material (numbered: WP-7) prepared by the preparation method in Example 2 were tested.

[0076] 1. Test the shielding performance of tungsten-based alloy composite shielding materials.

[0077] The shielding capability of tungsten-based alloy composite shielding materials is measured by dosimeters (such as Figure 3 The dosimeter measurement range is 1×10 -5 Gy / h~1×10-1 Gy / h, using 137 The shielding performance of tungsten-based alloy composite shielding materials was tested by Cs radiation source, and the γ shielding calculation model was as follows: Figure 1 As shown, for the convenience of comparison with lead, the shielding test results of the tungsten-based alloy composite shielding material samples are in the form of lead equivalent (mmPb). 137 The Cs radiation source shielding test result is 7.00mmPb (see Table 1).

[0078] 2. Test the radiation performance of tungsten-based alloy composite shielding materials.

[0079] The tungsten-based alloy composite shielding material was processed into in-pile irradiation samples (the outer dimensions of the tensile test were 90mm×15mm×5mm), and an out-of-pile cold test was carried out before irradiation. The in-pile irradiation test was completed in the Minjiang Test Reactor (MJTR), and the irradiation effect analysis of the samples was completed. The inspection contents included: appearance inspection, dimensional measurement, tensile test, etc.

[0080] After testing, the density of the 5mm thick tungsten-based alloy composite material prepared is 16.85g / cm 3 The average neutron injection of the sample is 4.83×10 18 n / cm 2 (E>1.0MeV), the appearance inspection before and after irradiation is as follows Figure 5 As shown in the figure, the tensile test results are as follows Figure 8 As shown in the figure, the maximum dimensional change before and after irradiation is 0.09mm (see Table 2). After irradiation, the tensile specimens all broke within the gauge length. The average yield strength of the specimens was 693MPa, the average tensile strength was 986MPa, and the average elongation after fracture was 14.08%. Compared with the unirradiated specimens, the yield strength of the specimens increased by 142MPa, the tensile strength increased by 64MPa, and the elongation decreased by about 4.08%.

[0081] Example 3

[0082] This embodiment provides a method for preparing a tungsten-based alloy composite shielding material. The difference from Embodiment 1 is that the mass fraction of tungsten powder used in this embodiment is 95%, the mass fraction of nickel powder is 3.5%, and the mass fraction of iron powder is 1.5%. The preparation is carried out by the following steps:

[0083] S1. Pre-treat tungsten powder, nickel powder and iron powder.

[0084] S2. The tungsten powder, nickel powder and iron powder obtained after the pretreatment are mixed according to the usage ratio and then ball-milled to obtain a mixed powder, wherein the mass fraction of the tungsten powder used is 95%, the mass fraction of the nickel powder is 3.5%, and the mass fraction of the iron powder is 1.5%.

[0085] The ball milling adopts a drum ball mill, the ball milling time is 48 hours, and the mass of the grinding balls is twice the total mass of the tungsten powder, nickel powder and iron powder.

[0086] S3, granulating the mixed powder by sieving.

[0087] S4. Use a 300-ton hydraulic press to press the mixed powder particles formed by granulation into a material blank.

[0088] During the pressing and molding, a paraffin system is selected as a molding agent, and the addition amount of the paraffin system is 1% of the total mass of tungsten powder, nickel powder and iron powder.

[0089] S5. Degrease the material body at a maximum temperature of 1100° C., and then sinter it in a hydrogen atmosphere at about 1550° C. for 2 hours to obtain a sample plate.

[0090] Among them, during degreasing, the flow rate of hydrogen is 1m 3 / h~3m 3 / h.

[0091] S6. The obtained plate is subjected to heat treatment and machining to obtain a tungsten-based alloy composite shielding material having a size of 150 mm×150 mm×5 mm.

[0092] The process temperature during heat treatment is 1000°C and the vacuum degree is <10Pa.

[0093] The shielding performance and radiation resistance performance of the tungsten-based alloy composite shielding material (numbered: WP-8) prepared by the preparation method in Example 3 were tested.

[0094] 1. Test the shielding performance of tungsten-based alloy composite shielding materials.

[0095] The shielding capability of tungsten-based alloy composite shielding materials is measured by dosimeters (such as Figure 3 The dosimeter measurement range is 1×10 -5 Gy / h~1×10 -1 Gy / h, using 137 The shielding performance of tungsten-based alloy composite shielding materials was tested by Cs radiation source, and the γ shielding calculation model was as follows: Figure 1 As shown, for the convenience of comparison with lead, the shielding test results of the tungsten-based alloy composite shielding material samples are in the form of lead equivalent (mmPb). 137 The Cs radiation source shielding test result is 7.29 mmPb (see Table 1).

[0096] 2. Test the radiation performance of tungsten-based alloy composite shielding materials.

[0097] The tungsten-based alloy composite shielding material was processed into in-pile irradiation samples (the outer dimensions of the tensile test were 90mm×15mm×5mm), and an out-of-pile cold test was carried out before irradiation. The in-pile irradiation test was completed in the Minjiang Test Reactor (MJTR), and the irradiation effect analysis of the samples was completed. The inspection contents included: appearance inspection, dimensional measurement, tensile test, etc.

[0098] After testing, the density of the 5mm thick tungsten-based alloy composite material prepared is 17.95g / cm 3 The average neutron injection of the sample is 4.10×10 18 n / cm 2 (E>1.0MeV), the appearance inspection before and after irradiation is as follows Figure 6 As shown in the figure, the tensile test results are as follows Fig. 9 As shown in the figure, the maximum dimensional change before and after irradiation is 0.30mm (see Table 2). The tensile tests all broke in the elastic stage, and the fracture position was at the transition arc at the upper end of the specimen. The average tensile strength before irradiation was 399MPa, and the average tensile strength after irradiation was 394MPa. There was no obvious change in tensile strength before and after irradiation.

[0099] Example 4

[0100] This embodiment provides a method for preparing a tungsten-based alloy composite shielding material. The difference from Embodiment 1 is that the mass fraction of tungsten powder used in this embodiment is 65%, the mass fraction of nickel powder is 24.5%, and the mass fraction of iron powder is 10.5%. The preparation is carried out by the following steps:

[0101] S1. Pre-treat tungsten powder, nickel powder and iron powder.

[0102] S2. The tungsten powder, nickel powder and iron powder obtained after the pretreatment are mixed according to the usage ratio and then ball-milled to obtain a mixed powder, wherein the mass fraction of the tungsten powder used is 65%, the mass fraction of the nickel powder is 24.5%, and the mass fraction of the iron powder is 10.5%.

[0103] The ball milling adopts a drum ball mill, the ball milling time is 48 hours, and the mass of the grinding balls is twice the total mass of the tungsten powder, nickel powder and iron powder.

[0104] S3, granulating the mixed powder by sieving.

[0105] S4. Use a 300-ton hydraulic press to press the mixed powder particles formed by granulation into a material blank.

[0106] During the pressing and molding, a paraffin system is selected as a molding agent, and the addition amount of the paraffin system is 1% of the total mass of tungsten powder, nickel powder and iron powder.

[0107] S5. Degrease the material body at a maximum temperature of 1100° C., and then sinter it in a hydrogen atmosphere at about 1350° C. for 2 hours to obtain a sample plate.

[0108] Among them, during degreasing, the flow rate of hydrogen is 1m 3 / h~3m 3 / h.

[0109] S6. The obtained plate is subjected to heat treatment and machining to obtain a tungsten-based alloy composite shielding material having a size of 150 mm×150 mm×5 mm.

[0110] The process temperature during heat treatment is 1000°C and the vacuum degree is <10Pa.

[0111] After testing, the density of the 5 mm thick tungsten-based alloy composite material prepared in Example 4 is 13.32 g / cm 3 , and its shielding performance was tested. The shielding ability of tungsten-based alloy composite shielding materials is measured by dosimeters (such as Figure 3 The dosimeter measurement range is 1×10 -5 Gy / h~1×10 -1 Gy / h, using 137 The shielding performance of tungsten-based alloy composite shielding materials was tested by Cs radiation source, and the γ shielding calculation model was as follows: Figure 1 As shown, for the convenience of comparison with lead, the shielding test results of the tungsten-based alloy composite shielding material samples are in the form of lead equivalent (mmPb). 137 The Cs radiation source shielding test result is 5.13 mmPb (see Table 1).

[0112] Example 5

[0113] This embodiment provides a method for preparing a tungsten-based alloy composite shielding material. The difference from Embodiment 1 is that the mass fraction of tungsten powder used in this embodiment is 97%, the mass fraction of nickel powder is 2.1%, and the mass fraction of iron powder is 0.9%. The preparation is carried out by the following steps:

[0114] S1. Pre-treat tungsten powder, nickel powder and iron powder.

[0115] S2. The tungsten powder, nickel powder and iron powder obtained after the pretreatment are mixed according to the usage ratio and then ball-milled to obtain a mixed powder, wherein the mass fraction of the tungsten powder used is 97%, the mass fraction of the nickel powder is 2.1%, and the mass fraction of the iron powder is 0.9%.

[0116] The ball milling adopts a drum ball mill, the ball milling time is 48 hours, and the mass of the grinding balls is twice the total mass of the tungsten powder, nickel powder and iron powder.

[0117] S3, granulating the mixed powder by sieving.

[0118] S4. Use a 300-ton hydraulic press to press the mixed powder particles formed by granulation into a material blank.

[0119] During the pressing and molding, a paraffin system is selected as a molding agent, and the addition amount of the paraffin system is 1% of the total mass of tungsten powder, nickel powder and iron powder.

[0120] S5. Degrease the material body at a maximum temperature of 1100° C., and then sinter it in a hydrogen atmosphere at about 1550° C. for 2 hours to obtain a sample plate.

[0121] Among them, during degreasing, the flow rate of hydrogen is 1m 3 / h~3m 3 / h.

[0122] S6. The obtained plate is subjected to heat treatment and machining to obtain a tungsten-based alloy composite shielding material having a size of 150 mm×150 mm×5 mm.

[0123] The process temperature during heat treatment is 1000°C and the vacuum degree is <10Pa.

[0124] After testing, the density of the 5 mm thick tungsten-based alloy composite material prepared in Example 5 is 18.44 g / cm 3 , and its shielding performance was tested. The shielding ability of tungsten-based alloy composite shielding materials is measured by dosimeters (such as Figure 3 The dosimeter measurement range is 1×10 -5 Gy / h~1×10 -1 Gy / h, using 137 The shielding performance of tungsten-based alloy composite shielding materials was tested by Cs radiation source, and the γ shielding calculation model was as follows: Figure 1 As shown, for the convenience of comparison with lead, the shielding test results of the tungsten-based alloy composite shielding material samples are in the form of lead equivalent (mmPb). 137 The Cs radiation source shielding test result is 7.34 mmPb (see Table 1).

[0125] Comparative Example

[0126] This comparative example provides a method for preparing a tungsten-based alloy composite shielding material. The difference from Example 1 is that the mass fraction of tungsten powder used in this example is 60%, the mass fraction of nickel powder is 28%, and the mass fraction of iron powder is 12%. The following steps are used for preparation:

[0127] S1. Pre-treat tungsten powder, nickel powder and iron powder.

[0128] S2. The tungsten powder, nickel powder and iron powder obtained after the pretreatment are mixed according to the usage ratio and then ball-milled to obtain a mixed powder, wherein the mass fraction of the tungsten powder used is 60%, the mass fraction of the nickel powder is 28%, and the mass fraction of the iron powder is 12%.

[0129] The ball milling adopts a drum ball mill, the ball milling time is 48 hours, and the mass of the grinding balls is twice the total mass of the tungsten powder, nickel powder and iron powder.

[0130] S3, granulating the mixed powder by sieving.

[0131] S4. Use a 300-ton hydraulic press to press the mixed powder particles formed by granulation into a material blank.

[0132] During the pressing and molding, a paraffin system is selected as a molding agent, and the addition amount of the paraffin system is 1% of the total mass of tungsten powder, nickel powder and iron powder.

[0133] S5. Degrease the material body at a maximum temperature of 1100° C., and then sinter it in a hydrogen atmosphere at about 1350° C. for 2 hours to obtain a sample plate.

[0134] Among them, during degreasing, the flow rate of hydrogen is 1m 3 / h~3m 3 / h.

[0135] S6. The obtained plate is subjected to heat treatment and machining to obtain a tungsten-based alloy composite shielding material having a size of 150 mm×150 mm×5 mm.

[0136] The process temperature during heat treatment is 1000°C and the vacuum degree is <10Pa.

[0137] The shielding performance of the tungsten-based alloy composite shielding material prepared by the preparation method in the comparative example was tested. The shielding ability of the tungsten-based alloy composite shielding material was measured by a dosimeter (such as Figure 3 The dosimeter measurement range is 1×10 -5 Gy / h~1×10 -1 Gy / h, using 137 The shielding performance of the tungsten-based alloy composite shielding material was tested by Cs radiation source. To facilitate comparison with lead, the shielding test results of the tungsten-based alloy composite shielding material samples were expressed in lead equivalent (mmPb). 137 The Cs radiation source shielding test result is 4.81mmPb.

[0138] By comparing the embodiment and the comparative example, it can be seen that the tungsten-based alloy prepared in the embodiment of the present invention has a large density and a better shielding effect than the comparative example, and has the following performance data:

[0139] The density of the material prepared by the method of the embodiment of the present invention is 13.32 g / cm 3 -18.44g / cm 3 Between, for 137 The Cs source emits gamma rays with an energy of 0.662 MeV. The lead equivalent of the 5 mm thick material is between 5.13 and 7.34 mmPb. The average neutron injection of the samples in the radiation resistance test of Examples 1-3 is 4.10 to 4.83 × 10 18 n / cm 2 (E>1.0MeV), the maximum size change before and after irradiation is 0.06-0.30mm, the tensile specimens that broke within the gauge length after irradiation, the average yield strength of the specimens is 627-693MPa, the average tensile strength is 930-986MPa, and the average elongation after breaking is 14.08-26.83%; at the same time, it can be seen from the material composition ratio and test results that the higher the tungsten content, the greater the density and the greater the lead equivalent. The other performance indicators of the tungsten-based alloy composite shielding material prepared in the embodiment of the present invention are tested in accordance with GB16363-1996 "X-ray protection material shielding performance and detection method", and also fully meet the national standard requirements for the shielding performance of radiation protection materials.

[0140] Table 1 Sample shielding test results

[0141] Example Specifications (mm) Lead equivalent (mmPb) Example 1 150×150×5 6.37 Example 2 150×150×5 7.00 Example 3 150×150×5 7.29 Example 4 150×150×5 5.13 Example 5 150×150×5 7.34

[0142] Table 2 Changes in sample size before and after irradiation (three samples were taken for testing in each of Examples 1 to 3)

[0143]

[0144] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A tungsten-based alloy composite shielding material, characterized in that: The tungsten-based alloy composite shielding material is made of tungsten powder, iron powder and nickel powder; The raw material components of the tungsten-based alloy composite shielding material include 65% to 97% tungsten powder in terms of mass percentage, and the remainder is nickel powder and iron powder, wherein the mass fraction ratio of nickel powder to iron powder is 7:

3.

2. A tungsten-based alloy composite shielding material according to claim 1, characterized in that: The raw material components of the tungsten-based alloy composite shielding material include, by mass percentage, 85% of tungsten powder and 15% of a mixture of nickel powder and iron powder, wherein the mass fraction ratio of the nickel powder to the iron powder is 7:

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3. The tungsten-based alloy composite shielding material according to claim 1, characterized in that: The raw material components of the tungsten-based alloy composite shielding material include, by mass percentage, 90% of tungsten powder and 10% of a mixture of nickel powder and iron powder, wherein the mass fraction ratio of the nickel powder to the iron powder is 7:

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4. The tungsten-based alloy composite shielding material according to claim 1, characterized in that: The raw material components of the tungsten-based alloy composite shielding material include, by mass percentage, 95% of tungsten powder and 5% of a mixture of nickel powder and iron powder, wherein the mass fraction ratio of the nickel powder to the iron powder is 7:

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5. A tungsten-based alloy composite shielding material according to any one of claims 1 or 2 to 4, characterized in that: The purity of the tungsten powder is greater than 99.95%, the purity of the nickel powder is greater than 99.5%, and the purity of the iron powder is greater than 99.5%.

6. A method for preparing a tungsten-based alloy composite shielding material, characterized in that: The following steps are involved: Tungsten powder, nickel powder and iron powder are mixed according to the usage ratio and then ball-milled to obtain mixed powder; Granulating and pressing the mixed powder to obtain a material body; After degreasing the material embryo, sintering is performed to obtain a plate; The plate is subjected to heat treatment and machining to obtain a tungsten-based alloy composite shielding material.

7. The method for preparing a tungsten-based alloy composite shielding material according to claim 6, characterized in that: Before mixing and ball-milling the tungsten powder, nickel powder and iron powder, the tungsten powder, nickel powder and iron powder were pretreated respectively. The pretreatment was carried out using a ball mill with a rotation frequency of 10 rpm for 24 hours.

8. The method for preparing a tungsten-based alloy composite shielding material according to claim 6, characterized in that: When granulating, sieving granulation is selected; when pressing and molding, the molding agent is a paraffin system; and hydrogen is used as the degreasing atmosphere.

9. The method for preparing a tungsten-based alloy composite shielding material according to claim 8, characterized in that: The addition amount of the paraffin system is 0.5% to 1.5% of the total mass of the raw materials.

10. The method for preparing a tungsten-based alloy composite shielding material according to any one of claims 7 to 9, characterized in that: The density of the prepared tungsten-based alloy composite shielding material is 13.32 g / cm 3 ~18.44g / cm 3 .

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