Method for coating boron

Abstract

The present application relates to a method for coating boron, to a boron-containing resin solution, to a boron-coated thermal neutron converter obtained by the method for coating boron, and further to a thermal neutron detector comprising the boron-coated thermal neutron converter. The method for coating boron as provided in the application is applicable for various substrates and has small restrictions on substrate shapes, particularly for substrates having complex surface structures and high aspect ratios.

Claims

1. A boron-containing resin solution comprising a solute and a solvent, the solute comprising boron powder, a resin and a curing agent, wherein the weight ratio of the solute to the solvent is from 1:1 to 1:20.

2. The boron-containing resin solution according to claim 1, wherein in the solute, the ratio of the total weight of the resin and curing agent to the weight of the boron powder is from 1:2 to 1:20.

3. The boron-containing resin solution according to claim 1, wherein in the solute, the weight ratio of the curing agent to the resin is from 1:3 to 1:5.

4. A method for coating boron, comprising the following steps: 1) applying the boron-containing resin solution according to claim 1 on an internal surface and/or an external surface of a substrate; 2) removing the solvent in the boron-containing resin solution and hardening the resin, to form a boron-containing coating layer on the surface of the substrate.

5. The method for coating boron according to claim 4, further comprising a pretreatment step prior to the step 1), wherein the pretreatment is to form a resin layer on the internal surface and/or external surface of the substrate.

6. The method for coating boron according to claim 5, wherein the pretreatment step comprises the following steps: a) weighing a resin, a curing agent and a solvent, and mixing them well to produce a resin solution; b) applying the resin solution on the internal surface and/or external surface of the substrate; c) removing the solvent in the resin solution and hardening the resin to form a resin layer on the surface of the substrate; wherein the ratio of the total weight of the resin and curing agent to the weight of the solvent is 1:2 to 1:6.

7. The method for coating boron according to claim 6, wherein, in the solute, the weight ratio of the curing agent to the resin is 1:3 to 1:5.

8. The method for coating boron according to claim 4, wherein in the step 1), the boron-containing resin solution is applied on the surface of the substrate by the means of brush coating, spray coating or dipping coating.

9. The method for coating boron according to claim 4, wherein in the step 2), a method of removing the solvent is to evaporate the solvent in the boron-containing resin solution by the means of baking.

10. A method for making a boron-coated thermal neutron converter, comprising the following steps: 1) preparing a substrate: 2) adhering a boron-containing coating layer on an internal surface and/or an external surface of the substrate using the method for coating boron according to claim 4.

11. The boron-containing resin solution according to claim 1, wherein the boron powder is a nanometer-sized boron powder.

12. The boron-containing resin solution according to claim 1, wherein the resin is an epoxy resin having a molecular weight from 200 to 500.

13. The boron-containing resin solution according to claim 12, wherein the resin selected from the group consisting of: bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy type resin vinyl ester resin and combinations thereof.

14. The boron-containing resin solution according to claim 1, wherein the curing agent is selected from the group consisting of: ethylenediamine, triethylamine, diethylenetriamine, triethylenetetramine, N,N-dimethylaminopropylamine, N,N-diethylaminopropylamine, xylenediamine, m-phenylenediamine and combinations thereof.

15. The boron-containing resin solution according to claim 1, wherein the solvent is a solvent having boiling point between 100° C. and 200° C.

16. The boron-containing resin solution according to claim 15, wherein the solvent is selected from the group consisting of: butyl glycidyl ether, benzyl glycidyl ether, phenyl glycidyl ether, ethylene glycol diglycidyl ether, alkylene glycidyl ether and combinations thereof.

17. The boron-containing resin solution according to claim 1, wherein the resin is a bisphenol A epoxy resin, the curing agent is triethylenetetramine, and the solvent is butyl glycidyl ether.

18. The method for coating boron according to claim 4, wherein the substrate is a metallic substrate or a non-metallic insulating substrate.

19. The method for coating boron according to claim 18, wherein the substrate is a substrate of aluminum, copper or Aramid paper.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a boron-coated sample obtained by using the method for coating boron of the application, with an Aramid paper honeycomb having a side length of 10 cm and an aspect ratio of 30:1 as the substrate.

(2) FIG. 2 shows a result of a boron-coated sample of Aramid paper honeycomb as observed by an electronic microscope, in which the thickness of the boron-containing coating layer is about 3.688 μm.

(3) FIG. 3 is a sample obtained after applying boron on the surface of an aluminum substrate having a length 100 mm and a width of 50 mm by using the method for coating boron of the application.

DETAILED DESCRIPTION OF THE INVENTION

(4) The embodiments of the present application will be described in detail as below by combining the examples. However, a person skilled in the art could understand that the following examples are only used to illustrate, but not regarded to limit the scope of the present application. The examples whose specific conditions are not specified shall be carried out at conventional conditions or conditions recommended by the manufacturer. All materials whose manufacturers are not specified are conventional products that can be purchased from the market.

(5) The materials and apparatus as used in the examples are introduced as follows:

(6) 1) Boron powder is nanometer-sized natural born powder, having an average particle size of 100 nm, commercially available from Hebei Zhongpuruituo Technology Co., Ltd.;

(7) 2) the substrate as used in Example 1 is an Aramid paper honeycomb having a side length of 1.83 mm, commercially available from Beijing Aoxing Boya Technology Development Co., Ltd., and the substrate as used in Example 2 is an aluminum sheet having a length of 100 mm, and a width of 50 mm;

(8) 3) The resin is a bisphenol A epoxy resin;

(9) 4) The solvent is 501 diluent (a butyl glycidyl ether);

(10) 5) The curing agent is triethylenetetramine;

(11) 6) The electronic microscope is Zeiss Auriga focal ion beam—field emission scanning electronic microscope from Carl Zeiss.

Example 1

(12) In the present example, nanometer-sized boron powder particles were utilized to complete the boron application on an Aramid paper honeycomb substrate having an aspect ratio of 30:1, to prepare a novel thermal neutron converter.

(13) The method for coating boron comprises the following steps:

(14) i) A substrate was prepared, its surface was cleaned, and it was weighed and its weight was recorded.

(15) ii) Applying a resin layer

(16) According to the following formula, a suitable amount of a resin solution was prepared by mixing well the following ingredients:

(17) resin:curing agent:solvent=250:62.5:1000 (weight ratio).

(18) The substrate was fully dipped into the resin solution and soaked for 20 min. Then the substrate was taken out of the resin solution and slightly drained, and thereafter, it was baked in an 140° C. baker for 30 to 40 min until the resin was completely cured, and the solvent was completely volatilized.

(19) After the temperature of the substrate was decreased to room temperature, it was weighted and its weight was recorded, and the increment of weight was found to be 3.9 g. By one application, the incremental thickness of the resin layer was about 1.5 μm.

(20) The resin solution was applied repeatedly and the application was conducted twice, and in each application, weighing and recording were necessary. The resin layer had a total increment of 7.8034 g, and a thickness of about 3.084 μm.

(21) iii) Applying a boron-containing coating layer

(22) According to the following formula, a suitable amount of the boron-containing resin solution was prepared by mixing well the following ingredients:

(23) nanometer-sized boron powder:resin:curing agent:solvent=180:16:4:1000 (weight ratio).

(24) The following conditions were required: the ratio of the weight of boron powder to the total weight of the resin and the curing agent was about 9:1; the ratio of the weight of solute (i.e., the total weight of boron powder, resin and curing agent) to the weight of solvent was about 1:5.

(25) The substrate coated with the resin layer on its surface was fully dipped into the boron-containing resin solution and soaked for 20 min.

(26) The substrate was taken out, and after slightly draining, it was placed in a 140° C. baker and baked for 30 to 40 min so that the resin was completely cured and the solvent was completely voatilized.

(27) The temperature of the substrate was decreased to room temperature, and after it was weighted and its weight was recorded, the increment of weight was 1.910 g.

(28) The average mass thickness of boron coated on the surface of the honeycomb was calculated, and according to the expected value of the boron-containing coating layer from 0.8 to 4 μm, it was to be determined whether it was necessary to continue to apply the boron-containing resin solution. If necessary, the process of soaking-baking-weighing-calculating was repeated until the thickness and the homogeneity both can meet requirements. In case of the boron-containing resin solution formula in the present example, generally, the boron application should be conducted 4 to 5 times.

(29) In this example, the boron-coated sample that was obtained by coating boron on the Aramid paper honeycomb having an aspect ratio of 30:1 was shown in FIG. 1. The fracture surface of the boron-containing coating layer was observed by an electron microscope, and as shown in FIG. 2, the thickness of the boron-containing coating layer was about 3.688 μm.

Example 2

(30) In the present example, nanometer-sized boron powder particles were utilized to complete the boron application on an aluminum substrate having a length of 100 mm and a width of 50 mm, to prepare a novel thermal neutron converter. With experiments, it was demonstrated that when using an aluminum substrate to carry out the boron application, better surface effects can be achieved if a boron-containing coating layer was directly applied without application of a resin layer.

(31) The method for coating boron comprises the following steps:

(32) i) A substrate was prepared, its surface was cleaned, and it was weighed and its weight was recorded.

(33) ii) Applying boron-containing coating layer

(34) According to the following formula, a suitable amount of the boron-containing resin solution was prepared by mixing well the following ingredients:

(35) nanometer-sized boron powder:resin:curing agent:solvent=180:16:4:1000 (weight ratio)

(36) The following conditions were required: the ratio of the weight of boron powder to the total weight of the resin and the curing agent was about 9:1; the ratio of the weight of solute (i.e., the total weight of boron powder, resin and curing agent) to the weight of solvent was about 1:5.

(37) The substrate with the cleaned surface was fully dipped into the boron-containing resin solution and soaked for 20 min.

(38) The substrate is taken out, and after slightly draining, it was placed in a 140° C. baker and baked for 30 to 40 min so that the resin was completely cured and the solvent was completely volatilized.

(39) The temperature of the substrate was decreased to room temperature, and after it was weighted and its weight was recorded, the increment of weight was 0.0261 g.

(40) The average mass thickness of boron coated on the surface of the aluminum sheet was calculated, and according to the expected value from 0.8 to 4 μm, it was to be determined whether it is necessary to continue to apply the boron-containing resin solution. If necessary, the process of soaking-baking-weighing-calculating was repeated until the thickness and the homogeneity both can meet requirements. In case of the boron-containing solution formula in the present example, generally, the boron application process should be conducted 2 to 4 times.

(41) In this present example, according to the above method, a boron-coated sample obtained after applying boron on the aluminum substrate having the length 100 mm and the width 50 mm was shown in FIG. 3. According to weight measurements, the thickness of the surface boron layer was calculated to be about 2.27 μm.

(42) The method for coating boron of the application can utilize nanometer-sized boron powder particles to prepare a micrometer-sized boron-containing coating layer, and it is applicable for various substrates and it has small restrictions on substrate shapes, particularly for substrates having complex surface structures and high aspect ratios. The method can achieve quick application of boron so that it can reduce the occupation time of the coating boron process, and thus it is suitable for streamlined and mass productions. The method for coating boron not only can use economic natural boron powder, but also use purified boron powder having high performance as raw material, and thus it is widely applicable.

(43) Although the specific embodiments of the present application have been described in detail, a person skilled in the art will understand that according to all the teachings that have been disclosed, various modifications and substitutions can be made to those details, all of which are within the protection scope of the application. The whole scope of the application is defined by the claims attached here and any equivalents thereof.