Silicon carbide and boron carbide composite material and preparation method thereof

Abstract

According to the silicon carbide and boron carbide composite material and the preparation method thereof provided by the invention, the silicon carbide and boron carbide composite material is prepared by adopting a manner of laminating and compounding cast sheets, arrangement of silicon carbide, boron carbide and an auxiliary agent is accurately controlled on the cast sheets through silk-screen printing, and then non-pressure powder burying sintering is carried out, so that the silicon carbide and boron carbide composite material is obtained. According to the preparation method, the components, the structure and the performance of the material can be accurately controlled so as to meet different application requirements.

Description

Technical Field

[0001] The invention relates to the technical field of special ceramic preparation, and in particular to a silicon carbide-boron carbide composite material and a preparation method thereof. Background Art

[0002] Silicon carbide and boron carbide have the advantages of high strength, high hardness, wear resistance, corrosion resistance, high temperature resistance, and stable properties. They are widely used engineering ceramic materials and play an important role in the field of inorganic materials. However, due to their chemical bonding characteristics, there is no slip system inside the material, and ion diffusion is difficult, resulting in problems such as inability to plastically deform, high brittleness, low toughness, difficulty in sintering, and high sintering temperature, which are subject to certain restrictions in production and application.

[0003] In order to improve the performance of silicon carbide and boron carbide materials, the existing technologies mainly have the following technical paths: (1) through the compounding of toughening materials, such as fiber toughening, granular material toughening, layered structure toughening, etc. However, toughening materials have problems such as difficulty in dispersion, easy agglomeration, high sintering temperature, and difficult composite process, resulting in the toughening effect being less than expected. (2) Adding liquid phase sintering aids. If the liquid phase aid is added too little, the performance improvement effect is not obvious; if too much is added, it will remain in the form of a glass phase at the matrix grain boundary, which will have an adverse effect on the hardness, wear resistance, and high temperature resistance of the material. In addition, the existing technology cannot effectively control the component distribution of the composite material, which limits its scope of application. Summary of the invention

[0004] In view of the deficiencies of the prior art, the technical problem to be solved by the present invention is how to control the component distribution of the silicon carbide boron carbide composite material and reduce the adverse effects of the liquid phase additive on the grain boundaries of the matrix material.

[0005] To solve the above problems, the present invention provides a method for preparing a silicon carbide boron carbide composite material, comprising the following steps:

[0006] S1, silicon carbide powder, boron carbide powder, binder, plasticizer, dispersant, and ethanol are mixed to prepare a casting slurry, and after casting, the casting slurry is cut into casting sheets A of the same specifications;

[0007] S2, mixing boron carbide powder, pineol, and a binder to obtain a first printing slurry;

[0008] S3, mixing silicon carbide powder, liquid phase sintering aid, pinene alcohol and binder to obtain a second printing slurry;

[0009] S4, screen printing the first printing slurry on one side surface of the cast sheet A to obtain a cast sheet B;

[0010] S5, screen printing the second printing paste on the printing surface of the cast sheet B to obtain a cast sheet C;

[0011] S6, stacking a plurality of the cast sheets C and pressing them to obtain a green body; or stacking at least one cast sheet C and at least one cast sheet A as a combined unit, stacking a plurality of the combined units, and pressing them to obtain a green body;

[0012] S7, dewaxing the green body, embedding it in sintering powder, embedding the powder and sintering to obtain the silicon carbide and boron carbide composite material.

[0013] The present invention adopts the method of stacking and compounding cast sheets to prepare silicon carbide-boron carbide composite materials, and accurately controls the arrangement of silicon carbide, boron carbide and additives on the cast sheets by screen printing, and then performs pressureless powder sintering. This preparation method can accurately control the composition, structure and performance of the material to meet different application requirements.

[0014] Furthermore, in the step S1, the mass ratio of the raw materials of the casting slurry is silicon carbide powder: boron carbide powder: binder: plasticizer: dispersant: ethanol = 40-45: 0.4-1: 5-6: 2-3: 0.2-0.5: 45-52.

[0015] Furthermore, in step S2, the mass ratio of the raw materials of the first printing paste is boron carbide powder: pineol: binder = 55-60: 33-40: 5-7.

[0016] Furthermore, in the step S3, the mass ratio of the raw materials of the second printing paste is silicon carbide powder: liquid phase sintering aid: pinene alcohol: binder = 50-56: 4-10: 33-40: 5-7.

[0017] By controlling the raw material components of the casting slurry and the printing slurry, the sintering aid pattern and the boron carbide hard filling points can be printed on the casting sheet, the distribution of the sintering aid can be controlled, and the adverse effects of the liquid phase additive on the grain boundaries of the matrix material can be greatly reduced.

[0018] Furthermore, in step S4, the printed pattern on the cast sheet A is selected from one of rectangle, square, circle and diamond, the fixed size range of the printed pattern is 0.2-5 mm, and the area of ​​the printed pattern occupies 30%-60% of the printed surface.

[0019] Furthermore, in step S5, the second printing paste covers the printed pattern on the cast sheet B.

[0020] Furthermore, in the step S4, the printing thickness of the first printing paste is 0.1-0.5 mm; and in the step S5, the thickness of the second printing paste is 0.1-0.3 mm.

[0021] By designing the printed graphics, the distribution of sintering aids and hard particles can be precisely controlled.

[0022] Furthermore, in step S6, the printing surfaces of the cast sheets C are stacked in the same direction, opposite directions or staggered.

[0023] Furthermore, in the step S6, the ratio of the number of the cast sheet C to the number of the cast sheet A used for stacking is 1:0-5.

[0024] The spatial distribution of the laminated sheets can be controlled by lamination pressing. By selecting different cast sheets and lamination methods, the composition and structure of the materials can be precisely controlled.

[0025] Furthermore, in step S7, the sintering powder includes silicon carbide powder and liquid phase sintering aid, and the mass ratio of each raw material of the sintering powder is silicon carbide powder: liquid phase sintering aid = 70-80: 20-30. The pressureless powder sintering is performed to effectively reduce the adverse effects of the aluminum liquid phase aid on the hardness and wear resistance of the material, and at the same time play a toughening effect. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation method and typical parameters of the present invention, and are not used to limit the parameter range described in the present invention. Reasonable changes derived therefrom are still within the scope of protection of the claims of the present invention.

[0027] It should be noted that the endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this article.

[0028] An embodiment of the present invention provides a method for preparing a silicon carbide boron carbide composite material, comprising the following steps:

[0029] S1. Preparation of silicon carbide cast sheet: Silicon carbide powder, boron carbide powder, binder, plasticizer, dispersant and ethanol are mixed to prepare casting slurry, and the casting slurry is cut into cast sheets A of the same specifications after casting. The typical thickness of the cast sheet A is 0.2-0.8 mm.

[0030] In a specific embodiment, the mass ratio of each raw material of the casting slurry is silicon carbide powder: boron carbide powder: binder: plasticizer: dispersant: ethanol = 40-45: 0.4-1: 5-6: 2-3: 0.2-0.5: 45-52. The particle size of silicon carbide powder is D50 = 0.5-1 μm; the particle size of boron carbide powder is 1-1.5 μm. The binder can be PVB30, PVB60, etc.; the plasticizer can be DOP, DBP, etc.; the dispersant can be Span 80, fish oil, etc.

[0031] S2. Prepare a first printing slurry: mix boron carbide powder, pineol, and a binder to obtain a first printing slurry.

[0032] In a specific embodiment, the mass ratio of each raw material of the first printing paste is boron carbide powder: pine alcohol: binder = 55-60: 33-40: 5-7. The particle size of the boron carbide powder is D50 = 1-1.5 μm. The binder can be PVB30, PVB60, etc.

[0033] S3. Prepare a second printing slurry: mix silicon carbide powder, a liquid phase sintering aid, pinene alcohol, and a binder to obtain a second printing slurry.

[0034] In a specific embodiment, the mass ratio of each raw material of the second printing paste is silicon carbide powder: liquid phase sintering aid: pine alcohol: binder = 50-56: 3-5: 33-40: 5-7. Typical liquid phase sintering aids include aluminum oxide and yttrium oxide, and the mass ratio is aluminum oxide: yttrium oxide = 1.5-1.7: 1. The particle size of silicon carbide powder is D50 = 0.5-1 μm, the particle size of aluminum oxide is D50 = 0.5-1 μm, the particle size of yttrium oxide is D50 = 1-1.5 μm, and the binder can be PVB30, PVB60, etc.

[0035] S4, screen printing the first printing slurry: screen printing the first printing slurry on one side of the cast sheet A, and obtaining the cast sheet B after drying.

[0036] In a specific embodiment, the printed pattern is a regular geometric shape, preferably a rectangle, square, circle, diamond, etc. The area of ​​the printed pattern accounts for 30% to 60% of the printed surface, and the shape size of the pattern (such as radius, side length, etc.) is selected in the range of 0.2 to 5 mm. The first printing paste pattern is evenly distributed, and the typical thickness is 0.1 to 0.5 mm.

[0037] S5, screen printing the second printing slurry: screen printing the second printing slurry on the printing surface of the cast sheet B, and obtaining the cast sheet C after drying.

[0038] In a specific embodiment, the second printing paste covers the printed pattern on the cast sheet B, and the thickness of the printed pattern is 0.1-0.3 mm.

[0039] S6. Stacking a plurality of cast sheets C and pressing them to obtain a green body; or stacking at least one cast sheet C and at least one cast sheet A as a combined unit, and stacking a plurality of combined units and pressing them to obtain a green body.

[0040] In a specific embodiment, the printing surfaces of the cast sheets C can be stacked in the same direction, opposite to each other or staggered; the ratio of the number of the cast sheets C to the number of the cast sheets A used is 1:0-5.

[0041] S7, dewaxing the green body, burying it in sintering powder, and performing reaction sintering to obtain a silicon carbide and boron carbide composite material.

[0042] In a specific embodiment, the sintering powder includes silicon carbide powder and a liquid phase sintering aid, and the mass ratio of each raw material is silicon carbide powder: liquid phase sintering aid = 70-80:20-30; a typical liquid phase sintering aid includes aluminum oxide and yttrium oxide, and the mass ratio is aluminum oxide: yttrium oxide = 1.5-1.7:1. The mass ratio of sintering powder to green body is 0.5-2:1. The sintering conditions are: temperature 1800-2000°C, and holding time 1-2h.

[0043] The above preparation method overcomes the limitations of traditional preparation processes. By printing a slurry of boron carbide and liquid-phase sintering aid on the cast sheet, the distribution of the sintering aid can be precisely controlled, which greatly reduces the adverse effects of the liquid-phase aid on the grain boundaries of the matrix material. Combined with lamination pressing and pressureless powder sintering, the composition distribution of the composite material can be controlled, and a composite material with excellent comprehensive properties such as hardness, wear resistance and toughness can be obtained.

[0044] The technical solutions and effects of the present invention are further described below in conjunction with specific embodiments.

[0045] Example 1

[0046] (1) Weigh 400 g of silicon carbide powder (particle size D50 = 0.5 μm), 4 g of boron carbide powder (particle size D50 = 1 μm), 50 g of PVB60, 20 g of DOP, 3 g of Span 80, and 500 g of anhydrous ethanol, mix and prepare a casting slurry, and cut into casting sheets A of the same specifications for standby use after casting. The thickness of the casting sheet A is 0.5 mm.

[0047] (2) Weigh 200 g of boron carbide powder (particle size D50=1 μm), 110 g of terpineol, and 20 g of PVB60, mix them, stir and mix, and homogenize them with a three-roll homogenizer to obtain a first printing slurry, which is then sealed and set aside.

[0048] (3) Weigh 150 g of silicon carbide powder (particle size D50 = 0.5 μm), 9 g of aluminum oxide (particle size D50 = 0.5 μm), 6 g of yttrium oxide (particle size D50 = 1 μm), 110 g of terpineol, and 20 g of PVB60, mix them, stir and mix, and homogenize them with a three-roll homogenizer to obtain a second printing slurry, which is then sealed and set aside.

[0049] (4) The first printing paste is screen-printed on one side of the cast sheet A. The shape of the printing paste is a circle with a radius of 1 mm. The area of ​​the printed pattern occupies 50% of the printed surface and the thickness is 0.3 mm. After drying, the cast sheet B is obtained.

[0050] (5) Screen-print a second printing paste on the printed surface of the cast sheet B to cover the printed pattern on the cast sheet B with a covering thickness of 0.2 mm. After drying, the cast sheet C is obtained and aged in a room temperature oven for 24 hours for later use.

[0051] (6) 20 sheets of cast sheets C are stacked, with the printed surfaces of each cast sheet C facing the same direction, and the pressing density is 2.0 g.cm -3 , and obtain a green body.

[0052] (7) Dewaxing the pressed green body and burying it in sintering powder. The mass ratio of silicon carbide powder and liquid phase sintering aid in the sintering powder is 4:1, the mass ratio of aluminum oxide and yttrium oxide in the liquid phase sintering aid is 1.5:1; the mass ratio of sintering powder to green body is 1:1. Heating to 1950°C, keeping the temperature for 1 hour, and cooling to obtain silicon carbide boron carbide composite material.

[0053] The performance of the silicon carbide boron carbide composite material prepared in this example was tested. 0.5 2900kg / mm 2 , volume wear rate 0.3mm 3 / h, fracture toughness 6.5mMPa.m 1 / 2 All wear tests are carried out under the same conditions using a friction and wear testing machine.

[0054] Example 2

[0055] (1) Weigh 400 g of silicon carbide powder (particle size D50 = 0.5 μm), 8 g of boron carbide powder (particle size D50 = 1 μm), 50 g of PVB60, 20 g of DOP, 3 g of Span 80, and 500 g of anhydrous ethanol, mix and prepare a casting slurry, and cut into casting sheets A of the same specifications for standby use after casting. The thickness of the casting sheet A is 0.5 mm.

[0056] (2) Weigh 200 g of boron carbide powder (particle size D50=1 μm), 110 g of terpineol, and 20 g of PVB60, mix them, stir and mix, and homogenize them with a three-roll homogenizer to obtain a first printing slurry, which is then sealed and set aside.

[0057] (3) Weigh 150 g of silicon carbide powder (particle size D50 = 0.5 μm), 9 g of aluminum oxide (particle size D50 = 0.5 μm), 6 g of yttrium oxide (particle size D50 = 1 μm), 110 g of terpineol, and 20 g of PVB60, mix them, stir and mix, and homogenize them with a three-roll homogenizer to obtain a second printing slurry, which is then sealed and set aside.

[0058] (4) The first printing paste is screen-printed on one side of the cast sheet A. The shape of the first printing paste is rectangular, the size is 2×4 mm, the area of ​​the printed pattern occupies 50% of the printed surface, and the thickness is 0.3 mm. After drying, the cast sheet B is obtained.

[0059] (5) Screen-print a second printing paste on the printed surface of the cast sheet B to cover the printed pattern on the cast sheet B with a covering thickness of 0.2 mm. After drying, the cast sheet C is obtained and aged in a room temperature oven for 24 hours for later use.

[0060] (6) One cast sheet C and one cast sheet A are stacked as a combined unit. Ten combined units are stacked so that the printed surfaces of the cast sheets C are arranged in the same direction. The pressing density is 2.0 g.cm -3 , and obtain a green body.

[0061] (7) Dewaxing the pressed green body and burying it in sintering powder. The mass ratio of silicon carbide powder and liquid phase sintering aid in the sintering powder is 4:1, the mass ratio of aluminum oxide and yttrium oxide in the liquid phase sintering aid is 1.5:1; the mass ratio of sintering powder to green body is 1:1. Heating to 1950°C, keeping the temperature for 1 hour, and cooling to obtain silicon carbide boron carbide composite material.

[0062] The performance of the silicon carbide boron carbide composite material prepared in this example was tested. 0.5 3000kg / mm 2 , volume wear rate 0.2mm 3 / h, fracture toughness 6.8mMPa.m 1 / 2 All wear tests are carried out under the same conditions using a friction and wear testing machine.

[0063] Example 3

[0064] (1) Weigh 420 g of silicon carbide powder (particle size D50 = 0.5 μm), 5 g of boron carbide powder (particle size D50 = 1 μm), 50 g of PVB60, 20 g of DOP, 5 g of Span 80, and 500 g of anhydrous ethanol, mix and prepare a casting slurry, and cut it into casting sheets A of the same specifications for standby use after casting. The thickness of the casting sheet A is 0.5 mm.

[0065] (2) Weigh 200 g of boron carbide powder (particle size D50=1 μm), 110 g of terpineol, and 20 g of PVB60, mix them, stir and mix, and homogenize them with a three-roll homogenizer to obtain a first printing slurry, which is then sealed and set aside.

[0066] (3) Weigh 150 g of silicon carbide powder (particle size D50 = 0.5 μm), 9 g of aluminum oxide (particle size D50 = 0.5 μm), 5 g of yttrium oxide (particle size D50 = 1 μm), 110 g of terpineol, and 20 g of PVB60, mix them, stir and mix, and homogenize them with a three-roll homogenizer to obtain a second printing slurry, which is then sealed and set aside.

[0067] (4) The first printing paste is screen-printed on one side of the cast sheet A in the shape of a 1×1 mm square. The area of ​​the printed pattern occupies 36% of the printed surface and the thickness is 0.3 mm. After drying, the cast sheet B is obtained.

[0068] (5) Screen-print a second printing paste on the printed surface of the cast sheet B to cover the printed pattern on the cast sheet B with a covering thickness of 0.2 mm. After drying, the cast sheet C is obtained and aged in a room temperature oven for 24 hours for later use.

[0069] (6) Stack two cast sheets A, and then sandwich the stacked cast sheets A with two cast sheets C, with the printed surfaces of the two cast sheets C facing each other, to form a combined unit. Stack 10 combined units and press them to a density of 2.0 g.cm -3 , and obtain a green body.

[0070] (7) Dewaxing the pressed green body and burying it in sintering powder. The mass ratio of silicon carbide powder and liquid phase sintering aid in the sintering powder is 4:1, the mass ratio of aluminum oxide and yttrium oxide in the liquid phase sintering aid is 1.5:1; the mass ratio of sintering powder to green body is 1:1. Heating to 1950°C, keeping the temperature for 1 hour, and cooling to obtain silicon carbide boron carbide composite material.

[0071] The performance of the silicon carbide boron carbide composite material prepared in this example was tested. 0.5 2800kg / mm 2 , volume wear rate 0.4mm 3 / h, fracture toughness 6.2MPa.m 1 / 2 All wear tests are carried out under the same conditions using a friction and wear testing machine.

[0072] Comparative Example 1

[0073] (1) Weigh 400 g of silicon carbide powder (particle size D50 = 0.5 μm), 6 g of boron carbide powder (particle size D50 = 1 μm), 25 g of aluminum oxide (particle size D50 = 0.5 μm), 15 g of yttrium oxide (particle size D50 = 1 μm), 50 g of PVB60, 20 g of DOP, 3 g of Span 80, and 500 g of anhydrous ethanol, mix and prepare a casting slurry, and cut into casting sheets A of the same specifications for standby use after casting. The thickness of the casting sheet A is 0.5 mm.

[0074] (2) 20 sheets of cast film A are stacked and pressed to a density of 2.0 g.cm-3 , and obtain a green body.

[0075] (3) Dewaxing the pressed green body and burying it in sintering powder. The mass ratio of silicon carbide powder and liquid phase sintering aid in the sintering powder is 4:1, the mass ratio of aluminum oxide and yttrium oxide in the liquid phase sintering aid is 1.5:1; the mass ratio of sintering powder to green body is 1:1. Heating to 1950°C, keeping the temperature for 1 hour, and cooling to obtain silicon carbide boron carbide composite material.

[0076] The performance of the silicon carbide boron carbide composite material prepared in this comparative example was tested. 0.5 2000kg / mm 2 , volume wear rate 0.9mm 3 / h, fracture toughness 6.0MPa.m 1 / 2 All wear tests are carried out under the same conditions using a friction and wear testing machine.

[0077] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for preparing a silicon carbide-boron carbide composite material, characterized in that: The following steps are involved: S1, silicon carbide powder, boron carbide powder, binder, plasticizer, dispersant, and ethanol are mixed to prepare a casting slurry, and after casting, the casting slurry is cut into casting sheets A of the same specifications; S2, mixing boron carbide powder, pineol, and a binder to obtain a first printing slurry; S3, mixing silicon carbide powder, liquid phase sintering aid, pinene alcohol and binder to obtain a second printing slurry; S4, screen printing the first printing slurry on one side surface of the cast sheet A to obtain a cast sheet B; S5, screen printing the second printing paste on the printing surface of the cast sheet B to obtain a cast sheet C; S6, stacking a plurality of cast sheets C and pressing to obtain a green body; Alternatively, at least one cast sheet C and at least one cast sheet A are superimposed as a combined unit, and a plurality of the combined units are stacked and pressed to obtain a green body; S7, dewaxing the green body, embedding it in sintering powder, embedding the powder and sintering to obtain the silicon carbide and boron carbide composite material.

2. The method for preparing the silicon carbide and boron carbide composite material according to claim 1, characterized in that: In the step S1, the mass ratio of the raw materials of the casting slurry is silicon carbide powder: boron carbide powder: binder: plasticizer: dispersant: ethanol = 40-45: 0.4-1: 5-6: 2-3: 0.2-0.5: 45-52.

3. The method for preparing the silicon carbide and boron carbide composite material according to claim 1, characterized in that: In the step S2, the mass ratio of the raw materials of the first printing paste is boron carbide powder: pineol: binder = 55-60: 33-40: 5-7.

4. The method for preparing the silicon carbide and boron carbide composite material according to claim 1, characterized in that: In the step S3, the mass ratio of the raw materials of the second printing paste is silicon carbide powder: liquid phase sintering aid: pinene alcohol: binder = 50-56: 4-10: 33-40: 5-7.

5. The method for preparing the silicon carbide and boron carbide composite material according to any one of claims 1 to 4, characterized in that: In step S4, the printed pattern on the cast sheet A is selected from one of rectangle, square, circle and rhombus, the fixed size range of the printed pattern is 0.2-5 mm, such as radius, side length, etc., the selection range is 0.2-5 mm, and the area of ​​the printed pattern occupies 30%-60% of the printing surface.

6. The method for preparing the silicon carbide and boron carbide composite material according to claim 5, characterized in that: In the step S5, the second printing paste covers the printed pattern on the cast sheet B.

7. The method for preparing the silicon carbide and boron carbide composite material according to claim 6, characterized in that: In the step S4, the printing thickness of the first printing paste is 0.1-0.5 mm; in the step S5, the thickness of the second printing paste is 0.1-0.3 mm.

8. The method for preparing the silicon carbide and boron carbide composite material according to any one of claims 1 to 4, characterized in that: In the step S6, the printing surfaces of the cast sheets C are stacked in the same direction, opposite directions or staggered.

9. The method for preparing the silicon carbide and boron carbide composite material according to claim 8, characterized in that: In the step S6, the ratio of the number of the cast sheet C to the number of the cast sheet A used for stacking is 1:0-5.

10. The method for preparing the silicon carbide and boron carbide composite material according to claim 1, characterized in that: In the step S7, the sintering powder includes silicon carbide powder and a liquid-phase sintering aid, and the mass ratio of the raw materials of the sintering powder is silicon carbide powder: liquid-phase sintering aid = 70-80: 20-30.