A hot pressing combination mold for oxide ceramic powder metallurgy

Abstract

This utility model relates to the field of hot pressing technology equipment for oxide ceramics, and discloses a hot pressing combination mold for oxide ceramic powder metallurgy, including a graphite base. A boron nitride boss is fitted onto the top of the inner wall of the graphite base. A boron nitride pressing plate is mounted on the top of the boron nitride boss, and a graphite pressing head is mounted on the top of the boron nitride pressing plate. A first boron nitride conical sleeve and a second boron nitride conical sleeve are provided on the left and right sides of the outer wall of the graphite pressing head. A graphite reinforcing sleeve is provided on the outer walls of both the first and second boron nitride conical sleeves. The bottom end of the outer wall of the graphite reinforcing sleeve is installed at the top of the outer wall of the graphite base. In this utility model, by using a chemically more stable boron nitride component to directly contact the oxide ceramic powder, direct contact between the powder and graphite is avoided, preventing the chemical reaction between the powder and graphite at high temperatures, preventing material carbonization and affecting its final properties, thereby improving the overall service life of the mold.

Description

Technical Field

[0001] This utility model relates to the field of oxide ceramic hot pressing technology equipment, and in particular to a hot pressing combination mold for oxide ceramic powder metallurgy. Background Technology

[0002] Oxide ceramics are structural materials composed of oxides. As a structural material, ceramics have excellent properties such as high hardness, high strength, low density, high temperature resistance and corrosion resistance. They are usually used to make refractory materials, heat insulation materials, crucibles for melting metals or alloys and related containers. In view of the influence of temperature and pressure factors on the hot pressing process of oxide ceramics, graphite molds are usually used under high temperature and high pressure.

[0003] While graphite molds possess advantages such as good thermal conductivity, high-temperature stability, and ease of processing, under high temperature and pressure conditions, the carbon elements in them readily react chemically with the metal oxides in the oxide ceramic powder, forming carbides or carbon-oxygen complexes. This reaction not only leads to the peeling or localized carbonization of the carbon layer on the mold surface, causing structural damage and shortening the mold's lifespan, but also introduces carbon impurities into the ceramic material, disrupting its original chemical composition and microstructure, thereby affecting the material's mechanical, electrical, and thermal properties. Furthermore, as the hot pressing process continues, the reaction at the mold-material interface intensifies, potentially leading to localized or even complete carbonization within the ceramic material, severely impacting the product's purity and functional characteristics. This adverse reaction not only increases the difficulty of process control but also results in frequent mold changes and material waste, significantly increasing production costs. Utility Model Content

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a hot-pressing combination mold for oxide ceramic powder metallurgy. This avoids direct contact between the powder and graphite, blocks the chemical reaction between the powder and graphite at high temperatures, prevents material carbonization and its impact on final performance, and thus improves the service life of the overall combination mold.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a hot pressing combination mold for oxide ceramic powder metallurgy, comprising a graphite base, a boron nitride boss being fitted onto the top of the inner wall of the graphite base, a boron nitride pressing plate being mounted on the top of the boron nitride boss, a graphite pressing head being mounted on the top of the boron nitride pressing plate, a first boron nitride conical sleeve and a second boron nitride conical sleeve being provided on the left and right sides of the outer wall of the graphite pressing head, a graphite reinforcing sleeve being provided on the outer walls of the first boron nitride conical sleeve and the second boron nitride conical sleeve, and a graphite reinforcing sleeve being provided on the outer wall bottom end of the graphite base.

[0006] Furthermore, the graphite base and the boron nitride boss are inlaid and assembled on the base.

[0007] Furthermore, a groove is formed at the top of the inner wall of the graphite base, and the size of the groove is adapted to the boron nitride boss.

[0008] Furthermore, the graphite reinforcing sleeve has a first boron nitride conical sleeve and a second boron nitride conical sleeve embedded inside it, and the outer circle of the complete circular conical sleeve formed by the combination of the first boron nitride conical sleeve and the second boron nitride conical sleeve fits into the inner circle of the graphite reinforcing sleeve.

[0009] Furthermore, the inner circles of the first and second boron nitride conical sleeves are clearance-fitted with the base of the boron nitride boss.

[0010] Furthermore, the inner circles of the first and second boron nitride conical sleeves are fitted with the boron nitride pressing sheet with a clearance fit.

[0011] Furthermore, the inner circles of the first and second boron nitride conical sleeves are clearance-fitted with the graphite indenter 4.

[0012] Furthermore, the inner cavities of the first and second boron nitride conical sleeves, from top to bottom, are: a graphite indenter, a boron nitride sheet, an oxide ceramic powder, and a boron nitride boss.

[0013] This utility model has the following beneficial effects:

[0014] In this invention, compared to traditional graphite molds, a boron nitride component with more stable chemical properties is used to directly contact the oxide ceramic powder, avoiding direct contact between the powder and graphite, blocking the chemical reaction between the powder and graphite at high temperatures, preventing material carbonization and affecting its final performance, and thus improving the service life of the overall mold assembly.

[0015] In this invention, the oxide powder is fixed by a hot pressing demolding device, thereby hot pressing the oxide powder. This allows for the hot pressing of micro-nano structures with high aspect ratios onto plate-shaped oxide powder, effectively improving the stability of the oxide powder during the hot pressing process and ensuring the forming accuracy of the micro-nano structures. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural schematic diagram of a hot pressing combined mold for oxide ceramic powder metallurgy proposed in this utility model;

[0017] Figure 2 This is a cross-sectional view of a hot pressing combination mold for oxide ceramic powder metallurgy proposed in this utility model;

[0018] Figure 3 This is an exploded view of a hot pressing combination mold for oxide ceramic powder metallurgy proposed in this utility model.

[0019] Legend:

[0020] 1. Graphite base; 2. Boron nitride boss; 3. Boron nitride pressing sheet; 4. Graphite pressing head; 5. First boron nitride conical sleeve; 6. Second boron nitride conical sleeve; 7. Graphite reinforcing sleeve; 8. Groove. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] Reference Figure 1 - Figure 3 This utility model provides an embodiment of a hot pressing combination mold for oxide ceramic powder metallurgy, comprising a graphite base 1, a boron nitride boss 2 fitted at the top of the inner wall of the graphite base 1, a boron nitride pressing plate 3 mounted at the top of the boron nitride boss 2, a graphite pressing head 4 mounted at the top of the boron nitride pressing plate 3, a first boron nitride conical sleeve 5 and a second boron nitride conical sleeve 6 provided on the left and right sides of the outer wall of the graphite pressing head 4, a graphite reinforcing sleeve 7 provided on the outer walls of the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6, the bottom end of the outer wall of the graphite reinforcing sleeve 7 being installed at the top of the outer wall of the graphite base 1, the graphite base 1 and the base of the boron nitride boss 2 being inlaid and assembled with a gap tolerance range of 0.06mm, a groove 8 being formed at the top of the inner wall of the graphite base 1, the size of the groove 8 being adapted to the boron nitride boss 2, and the interior of the graphite reinforcing sleeve 7 being... The sleeve is fitted with a first boron nitride conical sleeve 5 and a second boron nitride conical sleeve 6. The outer circle of the complete circular conical sleeve formed by the combination of the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6 matches the inner circle of the graphite reinforcing sleeve 7. The taper is within 1.2° and the tapers of the two sleeves are consistent. The inner circles of the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6 are clearance-fitted with the base of the boron nitride boss 2 with a clearance of 0.03 mm. The inner circles of the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6 are clearance-fitted with the boron nitride pressing sheet 3 with a clearance of 0.03 mm. The inner circles of the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6 are clearance-fitted with the graphite pressing head 4 with a clearance of 0.03 mm. The inner cavities of the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6, from top to bottom, are: graphite pressing head 4, boron nitride pressing sheet 3, oxide ceramic powder, and boron nitride boss 2.

[0023] Specifically, the diameter of the graphite base 1 corresponds to the outer diameter of the hot press worktable and the pressure column. The diameter of the groove 8 on the graphite base 1 corresponds to the diameter of the lower semicircle of the boron nitride boss 2. The outer diameter of the graphite reinforcing sleeve 7 is the same as the outer diameter of the graphite base 1. It is placed on the graphite base 1. The inner diameter of the graphite reinforcing sleeve 7 is tapered. In order to facilitate demolding, it can only be demolded in one direction. The outer diameter of the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6 combined into a whole circle has the same outer diameter tapered diameter as the inner diameter conical sleeve of the graphite reinforcing sleeve 7. The inner diameter of the whole circle combined with the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6 is the same as the diameter of the upper semicircle of the boron nitride boss 2. The diameters of the lower half of the boron nitride pressing plate 3, the boron nitride boss 2 and the graphite pressing head 4 are all the same. The oxide powder material is placed between the boron nitride boss 2 and the boron nitride pressing plate 3. The temperature and pressure of the hot press can be reasonably controlled to adjust the thickness of the oxide target material.

[0024] Working principle: The graphite base is installed on the outer diameter of the pressure column of the hot press workbench. Then, the bottom of the boron nitride boss 2 is embedded into the graphite base 1 by aligning it with the groove 8 on the graphite base 1. The graphite reinforcing sleeve 7 is then placed on the graphite base 1, and the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6 are embedded into the graphite reinforcing sleeve 7, so that the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6 are combined into a complete circle. The outer diameter taper of the two conical sleeves is consistent with the inner diameter of the graphite reinforcing sleeve 7, and the inner diameter of the complete circle formed by the two conical sleeves is consistent with the diameter of the upper semicircle of the boron nitride boss 2. Then, the oxide powder material is placed between the boron nitride boss 2 and the boron nitride pressing plate 3. The thickness of the oxide target material is adjusted by reasonably controlling the temperature and pressure of the hot press. Finally, the graphite pressing head 4 is embedded between the first boron nitride conical sleeve 5 and the second boron nitride conical sleeve 6, and it is confirmed that the bottom touches the nitride material under the boron nitride pressing plate 3.

[0025] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A hot-pressing combined die for oxide ceramic powder metallurgy, comprising a graphite base (1), characterized in that: The top of the inner wall of the graphite base (1) is fitted with a boron nitride boss (2), a boron nitride pressure plate (3) is installed on the top of the boron nitride boss (2), a graphite pressure head (4) is installed on the top of the boron nitride pressure plate (3), a first boron nitride conical sleeve (5) and a second boron nitride conical sleeve (6) are provided on the left and right sides of the outer wall of the graphite pressure head (4), a graphite reinforcing sleeve (7) is provided on the outer walls of the first boron nitride conical sleeve (5) and the second boron nitride conical sleeve (6), and the bottom of the outer wall of the graphite reinforcing sleeve (7) is installed on the top of the outer wall of the graphite base (1).

2. The hot-pressing combined mold for oxide ceramic powder metallurgy according to claim 1, characterized by: The graphite base (1) and the boron nitride boss (2) are inlaid and assembled.

3. A hot-pressing combined mold for oxide ceramic powder metallurgy according to claim 2, characterized in that: The graphite base (1) has a groove (8) at the top of its inner wall, and the size of the groove (8) is adapted to the boron nitride boss (2).

4. The hot press assembly mold for oxide ceramic powder metallurgy according to claim 1, characterized by: The graphite reinforcing sleeve (7) has a first boron nitride conical sleeve (5) and a second boron nitride conical sleeve (6) embedded inside. The outer circle of the complete conical sleeve formed by the combination of the first boron nitride conical sleeve (5) and the second boron nitride conical sleeve (6) matches the inner circle of the graphite reinforcing sleeve (7).

5. The hot press assembly mold for oxide ceramic powder metallurgy according to claim 1, characterized in that: The inner circles of the first boron nitride conical sleeve (5) and the second boron nitride conical sleeve (6) are in clearance fit with the base of the boron nitride boss (2).

6. A hot pressing combination mold for oxide ceramic powder metallurgy according to claim 1, characterized in that: The inner circles of the first boron nitride conical sleeve (5) and the second boron nitride conical sleeve (6) are fitted with the boron nitride pressure plate (3) with clearance.

7. A hot pressing combination mold for oxide ceramic powder metallurgy according to claim 1, characterized in that: The inner circles of the first boron nitride conical sleeve (5) and the second boron nitride conical sleeve (6) are fitted with the graphite indenter (4) with clearance.

8. A hot pressing combination mold for oxide ceramic powder metallurgy according to claim 1, characterized in that: The inner cavities of the first boron nitride conical sleeve (5) and the second boron nitride conical sleeve (6) are, from top to bottom: graphite indenter (4), boron nitride sheet (3), oxide ceramic powder, and boron nitride boss (2).

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