Binder for BJ forming refractory metal as well as preparation method and application of binder

Abstract

The invention discloses a binder for BJ forming refractory metal and a preparation method and application thereof, and belongs to the technical field of binder forming, the binder comprises the following raw materials by weight: 100-150 parts of a water-based ethylene-acrylic acid copolymer solution, 80-100 parts of a NaOH solution, 150-200 parts of ethanol, 20-40 parts of dioctyl phthalate, 10-30 parts of yttrium oxide powder, and 100-130 parts of diluted hydrochloric acid. And 200 to 300 parts of water. The binder for the BJ forming refractory metal is high in viscosity, high in bonding strength and capable of being degreased at the high temperature, has good compatibility, excellent adhesion capacity and stability on various refractory metals, has the advantages of being low in residue, easy to remove and the like, is high in degreasing and sintering compactness and excellent in mechanical property, and is suitable for large-scale production. The method is suitable for producing complex and high-performance refractory metal structural parts, and has important application in the fields of aerospace, national defense industry, nuclear industry, medical treatment and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of binder forming, and more particularly to a binder for BJ forming refractory metals, and a preparation method and application thereof. Background Art

[0002] With the development of cutting-edge industrial science and technology such as aerospace and defense industries, the requirements for complex configurations of high-performance refractory metals are becoming increasingly higher under specific environments. Binder jetting just meets its use requirements. However, the problem that remains unsolved is that the binder needs to have good compatibility with the metal powder and be completely removed during the sintering process without leaving any residue. At present, high adhesion, new environmental protection, and low carbon residue are the main research directions of binder jetting. In the binder jetting molding process of refractory metals, there is no binder that meets the use requirements.

[0003] Therefore, how to develop a binder for BJ (binder jet 3D printing technology) molding refractory metals and its preparation method and application is a technical problem that needs to be solved urgently by technical personnel in this field. Summary of the invention

[0004] In view of this, the present invention provides a binder for BJ forming refractory metals, and a preparation method and application thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A binder for BJ molding refractory metals comprises the following raw materials in parts by weight: 100-150 parts of aqueous ethylene-acrylic acid copolymer solution, 80-100 parts of NaOH solution, 150-200 parts of ethanol, 20-40 parts of dioctyl phthalate, 10-30 parts of yttrium oxide powder, 100-130 parts of dilute hydrochloric acid and 200-300 parts of water.

[0007] Beneficial effects of the invention: The invention innovatively develops a binder for BJ molding refractory metals with high viscosity, high bonding strength and high-temperature degreasing. It not only has good compatibility with a variety of refractory metals, excellent adhesion and stability, but also has the advantages of low residue and easy removal. It has high degreasing and sintering density and excellent mechanical properties. It is suitable for the production of complex, high-performance refractory metal structural parts and has important applications in aerospace, national defense industry, nuclear industry, medical and other fields.

[0008] Furthermore, the concentration of the NaOH solution is 0.5 mol / L, the concentration of the dilute hydrochloric acid is 4 mol / L, and the particle size of the yttrium oxide powder is 5-20 nanometers.

[0009] The present invention also provides a method for preparing a binder for BJ forming refractory metals, comprising the following steps:

[0010] (1) Weighing various raw materials according to the above-mentioned BJ forming refractory metal binder;

[0011] (2) mixing the aqueous ethylene-acrylic acid copolymer solution and the NaOH solution, heating and stirring, then adding ethanol, heating and stirring, and then adding dioctyl phthalate, heating and stirring, cooling to room temperature to obtain a solution for later use;

[0012] (3) Add yttrium oxide powder to dilute hydrochloric acid, mix, heat and stir, cool to room temperature, then add water, mix and stir at room temperature, then add the solution obtained in step (2), mix and stir at room temperature to obtain the above-mentioned binder for BJ forming refractory metals.

[0013] The beneficial effects of the present invention are as follows: the method adopts a plurality of viscous substances to be modified by step-by-step multi-stage physical blending to generate a binder for BJ molding refractory metals which has high viscosity, high bonding strength and can be degreased at high temperature.

[0014] Further, in step (2), the aqueous ethylene-acrylic acid copolymer solution and the NaOH solution are mixed, heated and stirred at 40±5°C for 60±10 min, with a stirring speed of 230 rpm, and then ethanol is added and mixed, heated and stirred at 40±5°C for 30±10 min, with a stirring speed of 260 rpm, and then dioctyl phthalate is added and mixed, heated and stirred at 60±5°C for 30±10 min, with a stirring speed of 260 rpm.

[0015] Furthermore, in step (3), yttrium oxide powder is added to dilute hydrochloric acid, mixed, heated at 80±5°C and stirred for 10±10 min, with a stirring speed of 120 rpm, cooled to room temperature, then added with water, mixed, stirred at room temperature for 30±10 min, with a stirring speed of 200 rpm / min, and then the solution obtained in step (2) is added, mixed, stirred at room temperature for 60±10 min, with a stirring speed of 260 rpm / min.

[0016] The present invention also provides a use of the above-mentioned binder for BJ molding refractory metals in binder injection molding of refractory metals.

[0017] Furthermore, the refractory metal is tungsten, rhenium or tantalum.

[0018] Further, the use of the above-mentioned binder for BJ forming refractory metal in binder injection molding of refractory metal comprises the following steps:

[0019] 1) Using the above-mentioned BJ forming refractory metal binder as a binder material, using tungsten powder, rhenium powder or tantalum powder as a printing powder material, printing into a desired model through a binder jetting molding process, cleaning the model, and obtaining a printed green body;

[0020] 2) The printed green body is placed in a plasma sintering furnace for degreasing, then removing yttrium oxide, and finally sintering at high temperature to obtain pure tungsten parts, pure rhenium parts or pure tantalum parts.

[0021] The beneficial effects of adopting the above further technical solution are: after BJ molding, and then processed by degreasing and sintering process, the final dense and excellent performance structural parts are obtained. This binder can realize BJ molding of pure tungsten powder; the structural restrictions can be ignored, and hollow, complex, and lattice structures that cannot be achieved by traditional technology can be formed; the pure tungsten parts prepared by this process have no effect on the purity of tungsten; the carbon content of pure tungsten parts is less than 0.001%.

[0022] Further, in step 2), the degreasing temperature is 0-800°C and the degreasing time is 5-6h;

[0023] The temperature for removing yttrium oxide is 800-2450°C, and the time for removing yttrium oxide is 20-30h;

[0024] The high-temperature sintering temperature of pure tungsten parts is 2300-3400℃, or the high-temperature sintering temperature of pure rhenium parts is 2300-3200℃, or the high-temperature sintering temperature of pure tantalum parts is 2300-3100℃, and the sintering time is 30-50h.

[0025] Furthermore, the particle size of the tungsten powder, rhenium powder or tantalum powder is 5-25 μm. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0027] The aqueous ethylene-acrylic acid copolymer solution used in the embodiments of the present invention is the glue of Shenzhen Xincheng Chemical Co., Ltd., brand: Xinlu, model: XC-3200.

[0028] Example 1

[0029] A method for preparing a binder for BJ forming refractory metals comprises the following steps:

[0030] (1) Weigh 100 g of aqueous ethylene-acrylic acid copolymer solution (EAA), 80 g of 0.5 mol / L NaOH solution, 150 g of ethanol, 20 g of dioctyl phthalate (DOP), 12 g of yttrium oxide powder with a particle size of 5-20 nm, 100 g of 4 mol / L dilute hydrochloric acid, and 200 g of purified water;

[0031] (2) mixing the aqueous ethylene-acrylic acid copolymer solution and the NaOH solution, heating and stirring at 40° C. for 60 min, with a stirring speed of 230 rpm, then adding ethanol, heating and stirring at 40° C. for 30 min, with a stirring speed of 260 rpm, then adding dioctyl phthalate, heating and stirring at 60° C. for 30 min, with a stirring speed of 260 rpm, and cooling to room temperature to obtain a solution for later use;

[0032] (3) Add yttrium oxide powder to dilute hydrochloric acid, heat and stir at 80°C for 10 minutes at a stirring speed of 120 rpm, cool to room temperature, then add water and stir at room temperature for 30 minutes at a stirring speed of 200 rpm / min, then add the solution obtained in step (2), stir at room temperature for 60 minutes at a stirring speed of 260 rpm / min, to obtain a binder for BJ molding refractory metals.

[0033] The method for preparing pure tungsten parts comprises the following steps:

[0034] 1) Using a binder for BJ forming refractory metal as a binder material and tungsten powder as a printing powder material, the desired model is printed through a binder jetting process, and the model is cured at 180°C for 2h, and the model is cleaned to obtain a printed green body;

[0035] 2) Place the printed green body into a plasma sintering furnace for degreasing, then remove yttrium oxide, and finally sinter at high temperature to obtain pure tungsten parts.

[0036] The temperature curve of step 2) is shown in Table 1:

[0037] Table 1 Temperature curve

[0038]

[0039]

[0040] Comparative Example 1

[0041] First, tungsten powder and organic binder are uniformly mixed and granulated, and then injected into the mold cavity by an injection molding machine under heated plasticization state (~150℃) for curing and forming. Then, the binder in the molded blank is removed by chemical or thermal decomposition method, and finally the final product is obtained by sintering and densification.

[0042] The viscosity of the adhesive was measured by a viscometer and was 3.2 cps. The surface tension was measured by a surface tension meter and was 16 mN / m.

[0043] Using infrared spectroscopy to measure the carbon content in pure tungsten parts;

[0044] Table 2 Carbon content of pure tungsten parts in Example 1

[0045] Sample 1 2 3 4 5 6 Carbon content PPM 0.0006 0.0001 0.0003 0.0002 0.0004 0.0003

[0046] Table 3 Comparative Example 1 Metal Injection Molding Carbon Content

[0047] Sample 1 2 3 4 5 6 Carbon content PPM 0.16 0.41 0.30 0.42 0.74 0.73

[0048] Table 4 Mechanical properties after sintering

[0049] Detection items Detection Methods The present invention Metal Injection Molding <![CDATA[Density g / cm 3 > Drainage method 19.1 18.9 Tensile strength MPa Electronic universal tensile testing machine 1023 965 Elongation % Electronic universal tensile testing machine 21 23 Dimensional accuracy % Vernier Calipers and Micrometers ±0.1 ±0.3 Shrinkage % Comparative calculation 16-17 15-25

[0050] Example 2

[0051] A method for preparing a binder for BJ forming refractory metals comprises the following steps:

[0052] (1) Weigh 120 g of an aqueous ethylene-acrylic acid copolymer solution, 90 g of a 0.5 mol / L NaOH solution, 170 g of ethanol, 25 g of dioctyl phthalate, 15 g of yttrium oxide powder having a particle size of 5-20 nm, 130 g of 4 mol / L dilute hydrochloric acid, and 220 g of purified water;

[0053] (2) mixing the aqueous ethylene-acrylic acid copolymer solution and the NaOH solution, heating and stirring at 40° C. for 60 min, with a stirring speed of 230 rpm, then adding ethanol, heating and stirring at 40° C. for 30 min, with a stirring speed of 260 rpm, then adding dioctyl phthalate, heating and stirring at 60° C. for 30 min, with a stirring speed of 260 rpm, and cooling to room temperature to obtain a solution for later use;

[0054] (3) Add yttrium oxide powder to dilute hydrochloric acid, heat and stir at 80°C for 10 minutes at a stirring speed of 120 rpm, cool to room temperature, then add water and stir at room temperature for 30 minutes at a stirring speed of 200 rpm / min, then add the solution obtained in step (2), stir at room temperature for 60 minutes at a stirring speed of 260 rpm / min, to obtain a binder for BJ molding refractory metals.

[0055] The method for preparing pure tungsten parts comprises the following steps:

[0056] 1) Using a binder for BJ forming refractory metal as a binder material and tungsten powder as a printing powder material, the desired model is printed through a binder jetting process, and the model is cured at 180°C for 2h, and the model is cleaned to obtain a printed green body;

[0057] 2) Place the printed green body into a plasma sintering furnace for degreasing, then remove yttrium oxide, and finally sinter at high temperature to obtain pure tungsten parts.

[0058] The temperature profile of step 2) is the same as that of embodiment 1.

[0059] The viscosity of the adhesive was measured by a viscometer and was 4.9 cps. The surface tension was measured by a surface tension meter and was 25 mN / m.

[0060] Using infrared spectroscopy to measure the carbon content in pure tungsten parts;

[0061] Table 5 Carbon content of pure tungsten parts in Example 2

[0062] Sample 1 2 3 4 5 6 Carbon content PPM 0.0006 0.0007 0.0003 0.0005 0.0007 0.0005

[0063] Table 6 Comparative Example 1 Metal Injection Molding Carbon Content

[0064] Sample 1 2 3 4 5 6 Carbon content PPM 0.16 0.41 0.30 0.42 0.74 0.73

[0065] Table 7 Mechanical properties after sintering:

[0066] Detection items Detection Methods The present invention Metal Injection Molding <![CDATA[Density g / cm 3 > Drainage method 19.2 18.9 Tensile strength MPa Electronic universal tensile testing machine 1009 965 Elongation % Electronic universal tensile testing machine 22 23 Dimensional accuracy % Vernier Calipers and Micrometers ±0.1 ±0.3 Shrinkage % Comparative calculation 16-17 15-25

[0067] Example 3

[0068] A method for preparing a binder for BJ forming refractory metals comprises the following steps:

[0069] (1) Weigh 150 g of aqueous ethylene-acrylic acid copolymer solution, 100 g of 0.5 mol / L NaOH solution, 200 g of ethanol, 40 g of dioctyl phthalate, 30 g of yttrium oxide powder with a particle size of 5-20 nm, 120 g of 4 mol / L dilute hydrochloric acid, and 300 g of purified water;

[0070] (2) mixing the aqueous ethylene-acrylic acid copolymer solution and the NaOH solution, heating and stirring at 40° C. for 60 min, with a stirring speed of 230 rpm, then adding ethanol, heating and stirring at 40° C. for 30 min, with a stirring speed of 260 rpm, then adding dioctyl phthalate, heating and stirring at 60° C. for 30 min, with a stirring speed of 260 rpm, and cooling to room temperature to obtain a solution for later use;

[0071] (3) Add yttrium oxide powder to dilute hydrochloric acid, heat and stir at 80°C for 10 minutes at a stirring speed of 120 rpm, cool to room temperature, then add water and stir at room temperature for 30 minutes at a stirring speed of 200 rpm / min, then add the solution obtained in step (2), stir at room temperature for 60 minutes at a stirring speed of 260 rpm / min, to obtain a binder for BJ molding refractory metals.

[0072] The method for preparing pure tungsten parts comprises the following steps:

[0073] 1) Using a binder for BJ forming refractory metal as a binder material and tungsten powder as a printing powder material, the desired model is printed through a binder jetting process, and the model is cured at 180°C for 2h, and the model is cleaned to obtain a printed green body;

[0074] 2) Place the printed green body into a plasma sintering furnace for degreasing, then remove yttrium oxide, and finally sinter at high temperature to obtain pure tungsten parts.

[0075] The temperature profile of step 2) is the same as that of embodiment 1.

[0076] The viscosity of the adhesive was measured by a viscometer and was 6.8 cps. The surface tension was measured by a surface tension meter and was 40 mN / m.

[0077] Using infrared spectroscopy to measure the carbon content in pure tungsten parts;

[0078] Table 8 Carbon content of pure tungsten parts in Example 3

[0079] Sample 1 2 3 4 5 6 Carbon content PPM 0.0007 0.0002 0.0005 0.0008 0.0004 0.0007

[0080] Table 9 Comparative Example 1 Metal Injection Molding Carbon Content

[0081]

[0082]

[0083] Table 10 Mechanical properties after sintering

[0084] Detection items Detection Methods The present invention Metal Injection Molding <![CDATA[Density g / cm 3 > Drainage method 19.3 18.9 Tensile strength MPa Electronic universal tensile testing machine 1107 965 Elongation % Electronic universal tensile testing machine 20 23 Dimensional accuracy % Vernier Calipers and Micrometers ±0.15 ±0.3 Shrinkage % Comparative calculation 17-18 15-25

[0085] Within the scope of the binder formula of the present invention, the carbon content does not change significantly and can be basically removed. Only the mechanical properties change to a certain extent, and the dimensional accuracy and shrinkage rate are slightly affected, but within a controllable range.

[0086] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A binder for BJ forming refractory metals, characterized in that: The invention comprises the following raw materials in parts by weight: 100-150 parts of aqueous ethylene-acrylic acid copolymer solution, 80-100 parts of NaOH solution, 150-200 parts of ethanol, 20-40 parts of dioctyl phthalate, 10-30 parts of yttrium oxide powder, 100-130 parts of dilute hydrochloric acid and 200-300 parts of water.

2. The binder for BJ forming refractory metal according to claim 1, characterized in that: The concentration of the NaOH solution is 0.5 mol / L, the concentration of the dilute hydrochloric acid is 4 mol / L, and the particle size of the yttrium oxide powder is 5-20 nanometers.

3. A method for preparing a binder for BJ forming refractory metals, characterized in that: The following steps are involved: (1) Weighing the raw materials of the binder for BJ forming refractory metal according to claim 1 or 2; (2) mixing the aqueous ethylene-acrylic acid copolymer solution and the NaOH solution, heating and stirring, then adding ethanol, heating and stirring, and then adding dioctyl phthalate, heating and stirring, cooling to room temperature to obtain a solution for later use; (3) Add yttrium oxide powder to dilute hydrochloric acid, mix, heat and stir, cool to room temperature, then add water, mix and stir at room temperature, then add the solution obtained in step (2), mix and stir at room temperature to obtain the binder for BJ forming refractory metals.

4. The method for preparing a binder for BJ forming refractory metal according to claim 3, characterized in that: In step (2), the aqueous ethylene-acrylic acid copolymer solution and the NaOH solution are mixed, heated and stirred at 40±5°C for 60±10 min, with a stirring speed of 230 rpm, and then ethanol is added, mixed, heated and stirred at 40±5°C for 30±10 min, with a stirring speed of 260 rpm, and then dioctyl phthalate is added, mixed, heated and stirred at 60±5°C for 30±10 min, with a stirring speed of 260 rpm.

5. The method for preparing a binder for BJ forming refractory metal according to claim 3, characterized in that: In step (3), yttrium oxide powder is added to dilute hydrochloric acid, mixed, heated at 80±5°C and stirred for 10±10 min, with a stirring speed of 120 rpm, cooled to room temperature, then added with water, mixed, stirred at room temperature for 30±10 min, with a stirring speed of 200 rpm / min, and then the solution obtained in step (2) is added, mixed, stirred at room temperature for 60±10 min, with a stirring speed of 260 rpm / min.

6. Use of the binder for BJ molding refractory metals according to claim 1 or 2 in binder injection molding of refractory metals.

7. The use of the binder for BJ molding refractory metal according to claim 6 in binder spray molding of refractory metal, characterized in that: The refractory metal is tungsten, rhenium or tantalum.

8. The use of the binder for BJ forming refractory metals according to claim 7 in binder spray forming of refractory metals, characterized in that: The following steps are involved: 1) using the BJ forming refractory metal binder as a binder material, using tungsten powder, rhenium powder or tantalum powder as a printing powder material, printing into a desired model through a binder jetting molding process, cleaning the model, and obtaining a printed green body; 2) The printed green body is placed in a plasma sintering furnace for degreasing, then removing yttrium oxide, and finally sintering at high temperature to obtain pure tungsten parts, pure rhenium parts or pure tantalum parts.

9. The use of the binder for BJ molding refractory metal according to claim 8 in binder spray molding of refractory metal, characterized in that: In step 2), the degreasing temperature is 0-800°C and the degreasing time is 5-6h; The temperature for removing yttrium oxide is 800-2450°C, and the time for removing yttrium oxide is 20-30h; The high-temperature sintering temperature of pure tungsten parts is 2300-3400℃, or the high-temperature sintering temperature of pure rhenium parts is 2300-3200℃, or the high-temperature sintering temperature of pure tantalum parts is 2300-3100℃, and the sintering time is 30-50h.

10. The use of the binder for BJ forming refractory metals according to claim 8 in binder spray forming of refractory metals, characterized in that: The particle size of the tungsten powder, rhenium powder or tantalum powder is 5-25 μm.

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