A method and apparatus for lamellar second phase orientation distribution and powder homogenization

Abstract

The application discloses a method and device for layer-shaped second phase directional distribution and powder homogenization loading, which comprises a feeding structure, a filler device and a stacking barrel; by virtue of the difference between the base powder and the shape and fluidity of the layer-shaped second phase, the layer-shaped second phase particle medium is directionally arranged in the base powder under the action of circulating rotation shearing, and the powder column is obtained by loading through continuous convex layer accumulation, and the density distribution of the filled powder column is uniform; the high performance and quality consistency of the powder metallurgy material are realized through layer-by-layer powder loading and second phase directional arrangement, and the overall density and density uniformity of the compact are improved.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy technology, specifically relating to a method and apparatus for the directional distribution of a lamellar second phase and the homogeneous packing of powder. Background Technology

[0002] With social development and technological progress, higher requirements have been placed on material performance indicators. Research on high-strength and high-toughness materials has always been a key direction in materials development. With the development of two-dimensional layered materials, the influence of the two-dimensional layered structure as the second phase of an alloy on material properties has become increasingly prominent, especially in cast materials such as copper and aluminum. Cast materials are produced by adding the second-phase alloying components under high-temperature melting conditions, which then disperse throughout the alloy material upon solidification. There are two main methods for the directional arrangement of the lamellar second phase in cast materials: one is to achieve the orientation of the lamellar material through the action of a magnetic or electric field during the casting process; the other is to reorient it through methods such as extrusion after the material is formed. Besides casting, powder metallurgy is another important method for forming metallic materials, and it has advantages that casting cannot match, such as lower forming temperatures and better arbitrary and uniform alloy element doping, making it the mainstream method for preparing high-temperature refractory metal materials. However, because it is difficult to achieve the directional arrangement of the lamellar second phase through an external physical field during the forming process of powder metallurgy materials, as is the case with cast materials, the orientation of the second phase in powder metallurgy materials has not yet made significant progress. Furthermore, the varying degrees of shrinkage during powder metallurgy preparation, including powder loading, molding, and sintering, negatively impact its performance. However, related research indicates that the arrangement of the layered second phase significantly affects material properties. In powder metallurgy, whether forming, sintering, or post-processing, surface and internal heterogeneity inevitably exists in the resulting samples. This heterogeneity greatly affects material properties, and results show that the powder loading method significantly influences the powder pressing process and the final compact density. Homogenization of powder loading is a crucial process in powder product preparation, ensuring product quality consistency and improving production efficiency while reducing costs. Therefore, addressing the arrangement of the lamellar second phase in powder metallurgy materials and achieving homogenization of powder loading is particularly important and urgent.

[0003] In powder metallurgy, powder loading is an essential step in powder forming. The homogenization and distribution of the powder directly affect subsequent pressing and sintering processes. Uneven density distribution during powder loading can lead to unstable product quality in sintering and subsequent processing. In powder metallurgy, powder is loaded into cold isostatic pressing sleeves or molding steel molds. The powder and its dopants are randomly distributed, making directional alignment impossible. Furthermore, because the loading process is a natural accumulation process, significant differences exist from top to bottom due to varying gravity. This is especially pronounced in large sleeves, where differences between top and bottom, and between the center and edges, are significant.

[0004] Research results show that materials with directional microstructure distribution exhibit superior mechanical properties, and materials with anisotropic lamellar structures demonstrate significant performance advantages in specific directions. This provides a new dimension and method for controlling material properties. Therefore, the powder loading stage is crucial for achieving the directional arrangement of the lamellar second phase and maximizing its performance advantages. Zhou Yan et al. from China University of Geosciences invented a directional powder feeding device and a melting and forming equipment in a selective zone. The powder to be processed moves below the powder-laying chamber via a powder-laying system, ensuring uniform distribution. Each time, the powder-laying system sequentially transfers the powder onto a substrate, layer by layer, ensuring a uniform directional arrangement of the powder in the two powder feeding cylinders on the substrate. This method uses specially treated spherical powder and does not address the directional arrangement of the lamellar second phase. Peng Qingyu et al. from Harbin Institute of Technology invented a molding method for graphene oxide-reinforced nylon composite materials, involving heating and melting the graphene oxide-reinforced nylon composite material, rolling and directionalizing it, cooling and shaping it, and performing multiple melting and directional processes. By applying force to molten graphene oxide-reinforced nylon composites using rollers, the graphene oxide is oriented and distributed within the nylon matrix under pressure, improving the dispersion and orientation of graphene oxide in the nylon. This method utilizes the directional flow of the molten material under rolling pressure, thereby achieving the directional arrangement of its lamellar phases. Furthermore, injection molding also utilizes the directional extrusion of a syringe to achieve the directional arrangement of the lamellar second phase in the slurry. The core of these methods is to utilize the flowability and directional action of the molten casting or slurry material to achieve the arrangement of the lamellar second phase. Although injection molding is also a molding method in powder metallurgy, offering advantages such as near-static forming, its application in bulk materials is limited due to the use of large amounts of organic matter and the resulting residues.

[0005] As explained above, castable and slurry materials possess fluidity, allowing for the directional arrangement of lamellar second phases under external and force fields. However, in powder metallurgy, due to the lack of fluidity of powder compared to fluids, the lamellar second phase is constrained by the positions of adjacent powder particles and cannot achieve directional arrangement during natural accumulation. Comparing casting and powder metallurgy, it is evident that the directional arrangement of lamellar second phases is a factual property achieved under external force. This is achieved by leveraging the differences in shape and fluidity between the matrix powder and the lamellar second phase. Specifically, under applied shear force, the polyhedral or near-spherical matrix powder exhibits a certain degree of fluidity, while the lamellar second phase shows almost no significant difference in fluidity, thus enabling the directional arrangement of the lamellar second phase. Summary of the Invention

[0006] To address the shortcomings of the existing technology, the present invention aims to provide a method and apparatus for the directional distribution of lamellar second phase and the homogeneous filling of powder, thereby solving the problems of directional arrangement of lamellar second phase and uniformity of powder filling during the powder metallurgy process, and achieving high performance and consistent quality of powder metallurgy materials.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] A lamellar second phase directional distribution and powder homogenization filling device includes a feeding structure, a filling device and a stacking barrel;

[0009] The filling device includes a rotating cone, a lifting platform, a conveyor belt, and a lifting machine. The rotating cone is mounted on the lifting platform via a rotating mechanism and suspended in the stacking drum. Driven by the lifting platform, the rotating cone can move up and down in the stacking drum. The lifting platform is mounted on the lifting machine and is driven to move up and down by the lifting machine. A rotating cylinder is vertically fixed to the top of the rotating cone and communicates with it. A discharge port is opened at the bottom of the rotating cone. A motor is also installed on the lifting platform. A pulley is installed on the output shaft of the motor. The pulley is connected to the rotating cylinder via a conveyor belt. The motor drives the rotating cone to rotate via the conveyor belt. Several powder flow channels are arranged vertically at equal intervals along the inner wall of the rotating cone.

[0010] The feeding structure includes a raw material barrel and a feeding mechanism. The feeding mechanism feeds the powder in the raw material barrel into a rotating cone. The rotating cone rotates and lifts the powder to form a directional distribution. The layered powder layer in the stacking barrel becomes a uniform density powder column.

[0011] Furthermore, the rotating cone includes an upper hemisphere and a lower conical sphere. The upper hemisphere has an opening facing downwards and an inlet at the top center that communicates with the rotating cylinder. Inside the upper hemisphere, there are several dividing strips extending from the inlet to the circular bottom edge of the upper hemisphere along the inner wall at equal angles, forming powder flow channels between the dividing strips.

[0012] The lower conical sphere gradually decreases in radius from the top circular edge to the bottom. The lower conical sphere has a discharge port. The top circular edge of the lower conical sphere is the same size as the bottom circular edge of the upper hemisphere and is sealed to the bottom circular edge of the upper hemisphere. Several protruding oblique teeth are evenly spaced along the side wall of the lower conical sphere from the top circular edge to the bottom discharge port. The protruding oblique teeth form channels corresponding to the powder flow channels in the upper hemisphere.

[0013] Furthermore, all the protruding helical teeth inside the rotating cone are inclined in the same direction, and each protruding helical tooth is not perpendicular to the side wall of the lower conical sphere at a certain angle.

[0014] Furthermore, the feeding mechanism includes a first spiral feeder and a powder funnel. The first spiral feeder feeds the powder in the raw material bucket into the powder funnel, which is installed above the rotating drum.

[0015] Furthermore, a second spiral feeder is provided inside the rotating drum, and the powder funnel is installed at the upper end of the second spiral feeder inside the rotating drum.

[0016] Furthermore, the stacking barrel is a cylindrical rubber sleeve, which is fixed to the base plate by a clamp, and the elevator is installed on the same base plate.

[0017] Furthermore, the powder stored in the raw material barrel is smoothly fed into the rotating cone through the feeding mechanism via a rotating drum. The feeding speed and flow rate are controlled when the angle is greater than the angle of repose. Under the action of gravity, the powder particles continuously flow from the rotating drum above the rotating cone into the rotating cone. During the flow of powder particles, the rotation speed and lifting speed of the rotating cone are controlled. Under the rotational driving force of the powder flow channel inside the rotating cone, the powder particles in the cylinder form a directional distributed layered powder layer under the cyclic rotational shearing action. As the rotating cone rotates continuously, it is lifted upward by the elevator to obtain a uniform density powder column in the stacking barrel under the corresponding equilibrium state.

[0018] The main advantages of this invention are:

[0019] 1. Excellent results. Utilizing the difference in shape and flowability between the matrix powder and the lamellar second phase, the lamellar second phase particles achieve directional alignment within the matrix powder under cyclic rotational shearing. A rotating cone simultaneously spreads the powder and lifts it upwards in a spiral, layered accumulation process to obtain powder columns. The filled powder columns have a uniform density distribution. Starting from the first step of powder metallurgy preparation—the powder loading stage—the high performance and consistent quality of powder metallurgy materials are achieved through spiral layer-by-layer powder loading and the directional alignment of the second phase.

[0020] Based on the significant difference in flowability between the matrix powder and the lamellar second phase, an external shear force is applied to achieve the directional arrangement of the lamellar second phase in the matrix powder. Simultaneously, the natural stacking during powder loading is transformed into a helical, quantitative stacking, improving the uniformity of the powder loading process. The flow characteristics of the powder and the density distribution of the compact differ greatly under different powder loading methods. Compared to traditional powder loading methods, helical layer-by-layer powder loading improves the movement of the powder and the transmission of force during pressing, facilitating radial flow of the powder and increasing the overall density and density uniformity of the compact.

[0021] 2. High efficiency. The powder particles inside the rubber sleeve simultaneously achieve directional arrangement and layered powder loading under the action of cyclic rotational shearing. Through the simultaneous rotation and upward lifting of the cone device, the powder column has uniform density and good consistency, providing a new method and approach for the directional distribution of layered second phase and uniform powder loading.

[0022] 3. Adjustable. The motion parameters of the rotating cone can be adjusted to obtain powder columns with uniform density, based on the different properties of the powder particles; this allows for good adjustability.

[0023] 4. The process is simple and suitable for industrial application. The powder homogenization and lamellar second phase directional distribution and filling process is simple, has high control precision, and is easy to operate. It can simultaneously realize the powder filling and lamellar second phase directional arrangement operations, resulting in high efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the layered second phase directional distribution and powder homogenization filling device of the present invention;

[0025] Figure 2 This is a top view of the rotating cone in this invention;

[0026] Figure 3 This is a front view of the rotating cone in this invention;

[0027] In the diagram: 1-Raw material bucket, 2-First spiral feeder, 3-Powder funnel, 4-Rotating cone, 5-Rubber sleeve, 6-Clamp, 7-Lifting platform, 8-Conveyor belt, 9-Elevator, 10-Protruding helical teeth, 11-Powder flow channel, 12-Second spiral feeder, 13-Powder particles. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1As shown, the layered second phase directional distribution and powder homogenization filling device of the present invention includes a feeding structure, a filling device, and a stacking barrel. The feeding structure includes a raw material barrel 1, a first screw feeder 2, and a powder funnel 3. The first screw feeder 2 feeds the powder in the raw material barrel 1 into the powder funnel 3, and the powder is fed into the filling device through the powder funnel 3. The filling device forms a directionally distributed layered powder layer in the stacking barrel to obtain a uniform density powder column.

[0030] like Figure 1 and Figure 2 As shown, the filling device includes a rotating cone 4, a lifting platform 7, a conveyor belt 8, and a lift 9. The rotating cone 4 is suspended in the stacking barrel by being mounted on the lifting platform 7 via a rotating mechanism. Driven by the lifting platform 7, the rotating cone 4 can move up and down in the stacking barrel. The lifting platform 7 is mounted on the lift 9 and is driven to move up and down by the lift 9. A rotating drum is vertically fixed at the top of the rotating cone 4, and the rotating drum is connected to the rotating cone 4. A discharge port is opened at the bottom of the rotating cone 4. A motor is also installed on the lifting platform 7, and a pulley is installed on the output shaft of the motor. The pulley is connected to the rotating drum via the conveyor belt 8, and the motor drives the rotating cone 4 to rotate via the conveyor belt 8. To ensure the stability of the powder conveying process, a second screw feeder 12 is installed inside the rotating drum, and a powder funnel 3 is installed at the upper end of the second screw feeder 12 inside the rotating drum.

[0031] like Figure 2 and Figure 3 As shown, the rotating cone 4 includes an upper hemisphere and a lower conical sphere. An inlet is located at the center of the top of the upper hemisphere, communicating with the rotating cylinder. Several dividing strips extending from the inlet to the circular bottom edge of the upper hemisphere are arranged along the inner wall at equal angles, forming powder flow channels 11 between each dividing strip. The lower conical sphere gradually decreases in radius from its top circular edge to its bottom edge, and has a discharge port. The top circular edge of the lower conical sphere is the same size as the circular bottom edge of the upper hemisphere and is sealed to it. Several protruding oblique teeth 10 are evenly spaced along the side wall of the lower conical sphere from the top circular edge to the bottom discharge port, forming channels corresponding to the powder flow channels 11 within the upper hemisphere.

[0032] like Figure 2 As shown, all the protruding helical teeth 10 inside the rotating cone 4 are inclined in the same direction, and each protruding helical tooth 10 is not perpendicular to the side wall of the lower conical sphere at a certain angle, which is more conducive to generating shear force on the passing powder. The stacking barrel is a cylindrical rubber sleeve 5, which is fixed to the base plate by a clamp 6, and the elevator 9 is also installed on the same base plate.

[0033] The powder stored in the raw material barrel 1 is fed into the powder funnel 3 by the screw feeder 2. The powder in the powder funnel 3 is smoothly fed into the rotating cone 4 by the second screw feeder 12 installed in the rotating drum. When the angle is greater than the angle of repose, the feeding speed and flow rate of the second screw feeder 12 are controlled. Under the action of gravity, the powder particles 13 continuously flow from the rotating drum above the rotating cone 4 into the rotating cone 4. During the flow of the powder particles 13, the rotation speed and lifting speed of the rotating cone 4 are controlled. Under the rotational pushing force of the flow channel in the rotating cone 4, the powder particles 13 in the cylinder are oriented and distributed in a layered powder layer under the cyclic rotational shearing action. As the rotating cone 4 rotates continuously, the rotating cone 4 is lifted upward by the elevator 9, so that a uniform density powder column is obtained in the rubber sleeve 5 under the corresponding equilibrium state.

[0034] The filling process of this invention is achieved through the following technical solution:

[0035] 1. The matrix powder is ball-milled or air-jet pulverized to break up any agglomerated powder particles;

[0036] 2. The matrix powder formed in step 1 is mixed with the lamellar second phase in a liquid-solid or solid-solid manner to form a pre-alloyed powder.

[0037] 3. The pre-alloyed powder is continuously and uniformly conveyed from the raw material hopper to the upper part of the rotating cone by a screw conveyor.

[0038] 4. The screw conveyor remains stationary, while the rotating cone rotates under the drive of the motor. Powder particles continuously and evenly enter the smooth channels at the top of the rotating cone and flow downwards along the channels under the action of gravity.

[0039] 5. The powder particles flow down from the channel and fall into the rubber sleeve through the gaps in the conical oblique teeth. After the powder fills the rotation blind area between the lower half of the rotating cone and the rubber sleeve, the specially shaped oblique teeth on the outside of the cone are in full contact with the powder particles.

[0040] 6. The powder particles flow from top to bottom along the powder slope inside the rubber sleeve in each oblique tooth gap. Under the rotational push of the specially shaped oblique teeth on the outside of the rotating cone, the powder particles form a very thin layer of powder due to shear stress.

[0041] 7. Activate the lifting device. As the rotating cone rotates, it slowly and uniformly rises, allowing the layered powder particles to continuously accumulate upwards, thus obtaining a powder column with uniform density. This simultaneously achieves a single operation of spiral-shaped, layer-by-layer powder loading and directional arrangement.

[0042] Based on the different powder particle characteristics and the processing steps involved, appropriate powder feeding speed, rotating cone speed, and lifting speed are determined. The powder continuously and uniformly passes through a specially shaped rotating cone 4 into the rubber sleeve 5. This invention innovatively employs a convex spiral layer-by-layer powder loading method, solving the problem of uneven powder loading through the accumulation of continuous powder layers. Furthermore, by applying external shear force, the directional arrangement of the layered second phase within the matrix powder is achieved. The process flow is minimally altered, operation is simple, and the results are significant.

Claims

1. A device for directional distribution of lamellar second phase and homogenization of powder filling, characterized in that: This includes the feeding structure, the filling device, and the stacking tank; The filling device includes a rotating cone (4), a lifting platform (7), a conveyor belt (8), and a lift (9); the rotating cone (4) is mounted on the lifting platform (7) and suspended in the stacking barrel by a rotating mechanism. Driven by the lifting platform (7), the rotating cone (4) can move up and down in the stacking barrel. The lifting platform (7) is mounted on the lift (9) and is driven up and down by the lift (9); the top of the rotating cone (4) is vertically fixed with a rotating cylinder connected to it, and the bottom of the rotating cone (4) has a discharge port. The lifting platform (7) is also equipped with a motor, and a pulley is mounted on the output shaft of the motor. The pulley is connected to the rotating cylinder by the conveyor belt (8), and the motor drives the rotating cone (4) to rotate by the conveyor belt (8); a number of powder flow channels (11) are arranged vertically at equal intervals along the inner wall of the rotating cone (4). The feeding structure includes a raw material barrel (1) and a feeding mechanism. The powder in the raw material barrel (1) is fed into the rotating cone (4) by the feeding mechanism. The powder is oriented by rotating and lifting the rotating cone (4). The layered powder layer is stacked in the barrel to form a uniform density powder column. The rotating cone (4) includes an upper hemisphere and a lower conical sphere. The upper hemisphere has an opening facing downwards and an inlet at the top center that communicates with the rotating cylinder. Inside the upper hemisphere, there are several dividing strips extending from the inlet to the circular bottom edge of the upper hemisphere along the inner wall at equal angles. Powder flow channels (11) are formed between the dividing strips. The lower conical sphere gradually decreases in radius from the top circular edge to the bottom. The lower conical sphere has a discharge port. The top circular edge of the lower conical sphere is the same size as the bottom circular edge of the upper hemisphere and is sealed to the bottom circular edge of the upper hemisphere. Several protruding oblique teeth (10) are evenly spaced along the side wall of the lower conical sphere from the top circular edge to the bottom discharge port. The protruding oblique teeth (10) form channels corresponding to the powder flow channels (11) in the upper hemisphere.

2. The lamellar second phase directional distribution and powder homogenization filling device as described in claim 1, characterized in that: All the protruding helical teeth (10) inside the rotating cone (4) are inclined in the same direction, and each protruding helical tooth (10) is not perpendicular to the side wall of the lower conical sphere at a certain angle.

3. The lamellar second phase directional distribution and powder homogenization filling device as described in any one of claims 1-2, characterized in that: The feeding mechanism includes a first spiral feeder (2) and a powder funnel (3). The first spiral feeder (2) feeds the powder in the raw material barrel (1) into the powder funnel (3), which is installed above the rotating drum.

4. The lamellar second phase directional distribution and powder homogenization filling device as described in any one of claims 1-2, characterized in that: The rotating drum is equipped with a second spiral feeder (12), and the powder hopper (3) is installed at the upper end of the second spiral feeder (12) inside the rotating drum.

5. The lamellar second phase directional distribution and powder homogenization filling device as described in any one of claims 1-2, characterized in that: The stacking barrel is a cylindrical rubber sleeve (5), which is fixed to the base plate by a clamp (6), and the elevator (9) is installed on the same base plate.

6. A powder filling method based on the lamellar second phase directional distribution and powder homogenization filling device as described in claim 1, characterized in that: The powder stored in the raw material barrel (1) is smoothly fed into the rotating cone (4) through the feeding mechanism via the rotating drum. The feeding speed and flow rate are controlled when the angle is greater than the angle of repose. Under the action of gravity, the powder particles (13) continuously flow from the rotating drum above the rotating cone (4) into the rotating cone (4). During the flow of the powder particles (13), the rotation speed and lifting speed of the rotating cone (4) are controlled. Under the rotational pushing force of the powder flow channel (11) in the rotating cone (4), the powder particles (13) in the cylinder form a directional distributed layered powder layer under the action of cyclic rotational shearing. While the rotating cone (4) rotates continuously, the rotating cone (4) is lifted upward by the elevator (9) to obtain a uniform density powder column in the stacking barrel under the corresponding equilibrium state.

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