Oxidation treatment device and method suitable for preparation of SiC powder particles for stirring casting

Abstract

The invention discloses an oxidation treatment device and method suitable for preparation of SiC powder particles for stirring casting, a stirring barrel is rotatably connected to a rack and is driven by a motor to rotate, a heat conduction barrel is coaxially fixed in the stirring barrel, a resistance heater extends into the heat conduction barrel along the axis direction of the heat conduction barrel, an air outlet hole is formed in the resistance heater, and the heat conduction barrel is coaxially fixed in the heat conduction barrel. And wet oxygen supplied by the wet oxygen supply system enters the stirring barrel through the air outlet hole. The low-cost characteristic of the oxidation treatment technology is combined, and low-cost production of the oxidized SiC powder particles can be achieved.

Description

Technical Field

[0001] The invention relates to an oxidation treatment device and method suitable for preparing SiC powder particles for stirring casting. Background Art

[0002] SiC p Reinforced aluminum-based composite materials have high specific strength and specific stiffness, low thermal expansion coefficient, good wear resistance, and good thermal and electrical conductivity. They have broad application prospects in aerospace and automotive fields. p The main preparation methods of reinforced aluminum-based composite materials include powder particle metallurgy, stirring casting and extrusion casting. Among them, the stirring casting method disperses the reinforcement particles evenly in the aluminum alloy melt through strong stirring, and then casts them into ingots and castings. This method has the advantages of simple process, low equipment investment and high production efficiency, and is expected to achieve SiC p Low-cost large-scale production of reinforced aluminum matrix composites. Stir casting to prepare SiC p In the process of strengthening aluminum-based composites, how to add SiC particles into the aluminum alloy melt and disperse them evenly is the most critical issue.

[0003] Since SiC particles have very poor wettability with aluminum alloy melt, the surface of the ceramic particles must be oxidized or coated with a metal coating to improve the wettability between the SiC particles and the aluminum melt. Compared with coating with a metal coating, the cost of surface oxidation treatment is significantly lower and has less impact on the composition of the melt and the final product. However, in actual production, it is found that during the high-temperature oxidation process of SiC powder particles, due to the formation of SiO2 on the surface of the particles, the surface of the powder particles is prone to hardening and hardening, which hinders the oxidation of the internal SiC powder particles. The thickness of the powder particle layer must be reduced and ground and turned multiple times to obtain oxidized particles that meet the requirements of stirring casting, which seriously limits the improvement of production efficiency.

[0004] Therefore, the present invention has developed an oxidation treatment device and method suitable for preparing SiC powder particles for stir casting, which combines a resistance heater, drum stirring and a wet oxygen atmosphere, and can efficiently oxidize SiC powder particles through effective control of temperature and oxygen flow rate to meet the needs of industrial production of SiC p Requirements for reinforced aluminum matrix composites. Summary of the invention

[0005] The present invention aims to solve the problems existing in the above-mentioned prior art and to provide an oxidation treatment device and method suitable for preparing SiC powder particles for stirring casting.

[0006] The technical solutions adopted in the present invention are: The invention discloses an oxidation treatment device suitable for preparing SiC powder particles for stirring casting, comprising a stirring barrel, a resistance heater, a heat-conducting barrel, a motor, a frame and a wet oxygen supply system. The stirring barrel is rotatably connected to the frame and driven to rotate by the motor. The heat-conducting barrel is coaxially fixed in the stirring barrel. The resistance heater extends into the heat-conducting barrel along the axial direction of the heat-conducting barrel. An air outlet is provided on the resistance heater. The wet oxygen supplied by the wet oxygen supply system enters the stirring barrel through the air outlet.

[0007] Furthermore, the mixing barrel includes a semi-circular barrel, an end seat and a support shaft. There are two semi-circular barrels, one of which is fixed with an end seat at both ends, and two support shafts are fixed to the outer sides of the two end seats respectively. The support shaft is rotatably connected to the frame, and the two semi-circular barrels are spliced ​​and fixed to each other to form a round barrel.

[0008] Furthermore, tapered openings are provided on the inner walls at both ends of the semi-circular barrels. After the two semi-circular barrels are spliced ​​and fixed, the corresponding two tapered openings are spliced ​​to form a conical cavity.

[0009] Furthermore, a plurality of vents are provided on the conical surface of the cone mouth, filters are laid on the vents, and the air outlet holes on the resistance heater are placed in the conical cavity.

[0010] Furthermore, the air outlet holes on the resistance heater are distributed at both ends of the resistance heater, and a ventilation cavity is provided in the axial direction of the resistance heater, the ventilation cavity is connected with the air outlet holes, and the ventilation cavity is used to introduce wet oxygen.

[0011] Furthermore, the two half barrels are fixed by a lock, and a concave surface and a convex surface that cooperate with each other are provided at the joint surface of the two half barrels.

[0012] Furthermore, stirring ribs are provided on the inner wall of the stirring barrel.

[0013] The present invention also discloses an oxidation treatment method, comprising the following steps: S1) filtering SiC powder particles to select SiC particles that meet the size range, and washing the selected SiC particles; S2) SiC powder particles and ceramic balls are added to the mixing barrel, and the resistance heater is turned on. After the mixing barrel is heated to the required temperature, the motor drives the mixing barrel to rotate to prevent the SiC powder particles from agglomerating. After the temperature continues to rise, wet oxygen is introduced for oxidation treatment; S3) After the oxidation treatment is completed, the resistance heater is turned off and the wet oxygen supply is stopped. After the temperature drops to the required temperature, the stirring barrel is stopped, and then the oxidized SiC powder particles and ceramic balls are poured out; S4) Add SiC powder particles and ceramic balls into the mixing tank, and repeat S1) to S4) to continue to prepare new oxidized SiC powder particles.

[0014] Furthermore, in S1), the SiC powder particles are ultrasonically cleaned using a low concentration hydrochloric acid solution or water.

[0015] Further, in S2), after the stirring barrel is heated to above 800°C, the motor drives the stirring barrel to rotate; after the temperature is raised to 1000°C, wet oxygen is introduced and oxidation treatment is performed at 1100°C, with a flow rate greater than 50 ml / min and a treatment time of 30 minutes.

[0016] The present invention has the following beneficial effects: 1) The device of the present invention has a simple structure and low manufacturing or modification cost. Combined with the low-cost characteristics of the oxidation treatment technology itself, it can achieve low-cost production of oxidized SiC powder particles.

[0017] 2) The present invention places the resistance heater at the axial center of the stirring barrel and keeps the position stationary. The stirring barrel rotates, so that during the preparation and mixing process, the SiC powder particles and the ceramic balls are heated more evenly, thereby ensuring the oxidation effect.

[0018] 3) The present invention oxidizes SiC powder particles by means of a drum-type heating tube. During the oxidation process, the drum rotates and the stirring ribs stir, thereby preventing the SiC powder particles from agglomerating and increasing the contact area with oxygen, thereby obtaining oxidized SiC powder particles with uniform quality.

[0019] 4) The present invention can increase the amount of SiC powder particles that can be oxidized in a single process. The wet oxygen atmosphere used can significantly shorten the time required for a single oxidation process. At the same time, after pouring out the oxidized SiC powder particles, a new batch of powder particles can be oxidized, which ultimately greatly improves the production efficiency of the oxidized powder particles.

[0020] 5) The oxidation rate of SiC powder in the present invention is significantly accelerated when the oxidation treatment is performed at a temperature of 1100°C. At 1100°C, the solubility of water molecules in wet oxygen in the oxide film is higher than that of oxygen, and the carbon atoms in the oxide can be removed by forming hydrocarbons. The oxidation rate is faster than that of dry oxygen. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural diagram of the device of the present invention.

[0022] Figure 2 This is a structural diagram of one of the half barrels after it was disassembled.

[0023] Figure 3 A cross-sectional view of the resistance heater in the mixing tank.

[0024] Figure 4 It is the structural diagram of the resistance heater and the heat conduction barrel.

[0025] Figure 5XRD diffraction results of oxidized SiC powder particles.

[0026] Figure 6 Microstructure image of SiCp reinforced aluminum matrix composite material. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings.

[0028] like Figure 1 and Figure 2 The present invention discloses an oxidation treatment device for preparing SiC powder particles for stirring casting, comprising a stirring barrel 1, a resistance heater 2, a heat-conducting barrel 3, a motor 4, a frame 5 and a wet oxygen supply system. The stirring barrel 1 is rotatably connected to the frame 5 and driven to rotate by the motor 4. The heat-conducting barrel 3 is coaxially fixed in the stirring barrel 1. The resistance heater 2 extends into the heat-conducting barrel 3 along the axial direction of the heat-conducting barrel 3. The resistance heater 2 is fixed in position and does not rotate with the heat-conducting barrel 3. An air outlet 20 is provided on the resistance heater 2, and wet oxygen (wet oxygen refers to oxygen mixed with water vapor) supplied by the wet oxygen supply system enters the stirring barrel 1 through the air outlet.

[0029] The mixing barrel 1 in the present invention comprises a semi-circular barrel 11, an end seat 12 and a support shaft 13. Two semi-circular barrels 11 are provided, wherein an end seat 12 is fixed at both ends of one semi-circular barrel 11, and two support shafts 13 are fixed to the outer sides of the two end seats 12 respectively. The support shaft 13 is rotatably connected to the frame 5 through a bearing seat, and the two semi-circular barrels 11 are spliced ​​and fixed to each other to form a round barrel.

[0030] The two half barrels 11 are fixed by a lock, which is convenient for loading and unloading. In order to ensure the sealing of the two half barrels 11, a concave surface and a convex surface that match each other are provided at the joint surface of the two half barrels 11.

[0031] In order to increase the stirring efficiency, stirring ribs are provided on the inner wall of each semi-circular barrel 11 .

[0032] Combination Figure 3 A conical opening 111 is provided on the inner wall at both ends of the semi-circular barrel 11. After the two semi-circular barrels 11 are spliced ​​and fixed, the corresponding two conical openings 111 are spliced ​​to form a conical cavity 110, and the cone angle of the conical cavity 110 faces inward. The heat-conducting barrel 3 is placed in the semi-circular barrel 11, and the conical opening 111 on the semi-circular barrel 11 fixed to the end seat 12 is fixedly connected to the two ends of the heat-conducting barrel 3.

[0033] The heat-conducting barrel 3 is made of alumina and has an outer diameter of 150 mm. The present invention places the resistance heater at the axial center of the stirring barrel 1 and keeps the position stationary. The stirring barrel 1 rotates, and during the process of preparing the mixing material, the SiC powder particles and the ceramic balls are heated more evenly to ensure the oxidation effect.

[0034] Since one of the semi-circular barrels 11 is detachable, after the semi-circular barrel 11 is removed, each end port of the heat-conducting barrel 3 will be half-open. In order to prevent materials from falling into the heat-conducting barrel 3, a semi-circular rib is provided at each end of the heat-conducting barrel 3, which just cooperates with the non-detachable semi-circular barrel 11 to completely close each end of the heat-conducting barrel 3.

[0035] In order to allow wet oxygen to enter the mixing barrel 1 (i.e., the cavity between the two conical cavities 110), a plurality of vents are provided on the conical surface of the conical opening 111, and a filter screen is laid on the vents. The air outlet 20 on the resistance heater 2 is placed in the conical cavity 110. After wet oxygen is introduced, the wet oxygen enters the conical cavity 110 from the air outlet 20, and then enters the mixing barrel 1 from the conical cavity 110.

[0036] like Figure 4 The air outlet holes 20 on the resistance heater 2 are distributed at both ends of the resistance heater, and a ventilation cavity is provided in the axial direction of the resistance heater 2. The ventilation cavity is connected with the air outlet holes 20, and the ventilation cavity is used to introduce wet oxygen.

[0037] The oxidation treatment method of the present invention is: S1) Pre-treating SiC powder particles.

[0038] SiC particles with a diameter of about 50 μm were screened out using a 300-1000 mesh screen, totaling 2000 g; a low-concentration hydrochloric acid solution was prepared, with the ratio of hydrochloric acid to water being 1:100-200, and the SiC powder particles were ultrasonically cleaned.

[0039] S2) Oxidation treatment of SiC powder particles.

[0040] SiC powder particles and ceramic balls (mass ratio of about 1:1) are added into the stirring barrel, and the resistance heater is turned on. After the stirring barrel is heated to 800°C, the motor drives the stirring barrel to rotate to prevent the SiC powder particles from clumping. After the temperature continues to rise to 1000°C, wet oxygen is introduced and oxidation treatment is carried out at 1100°C for 30 minutes.

[0041] S3) After the oxidation treatment is completed, the resistance heater is turned off and the wet oxygen supply is stopped. After the temperature drops below 800°C, the stirring barrel is stopped, and then the oxidized SiC powder particles and ceramic balls are poured out; S4) Add SiC powder particles and ceramic balls into the mixing tank, and repeat S1) to S4) to continue to prepare new oxidized SiC powder particles.

[0042] The SiC powder particles after oxidation treatment were randomly sampled and XRD analysis was performed. The results are shown in the attached figure. Figure 5 Compared with the initial SiC powder particles, a certain amount of SiO2 is formed after oxidation treatment.

[0043] Aluminum alloy smelting: The base aluminum alloy material is conventional A360 alloy, and the aluminum alloy block is cut by wire cutting, with a total weight of about 8kg. A simple pit furnace is used for smelting, and the smelting temperature is about 700℃.

[0044] Preparation of SiC by stirring casting p Strengthen aluminum-based composite materials. Stir the aluminum liquid at a speed of 800-1000r / min to ensure that the aluminum liquid forms a stable vortex. Add the oxidized SiC powder particles at a speed of about 150g / min. During the stirring process, the temperature of the aluminum liquid is controlled at around 620°C, and the fluctuation range does not exceed ±10°C. After all the SiC powder particles are added, continue stirring for 30 minutes. Raise the temperature to 680°C and keep warm for 10 minutes, and add a degasser to degas in order to reduce the gas and impurity content in the melt. Finally, pour the aluminum alloy melt into the mold to complete the casting and obtain SiC p Reinforced aluminum matrix composite material blank, microstructure as attached Figure 6 shown.

[0045] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. An oxidation treatment device suitable for preparing SiC powder particles for stirring casting, characterized in that: The invention comprises a stirring barrel (1), a resistance heater (2), a heat-conducting barrel (3), a motor (4), a frame (5) and a wet oxygen supply system. The stirring barrel (1) is rotatably connected to the frame (5) and driven to rotate by the motor (4). The heat-conducting barrel (3) is coaxially fixed in the stirring barrel (1). The resistance heater (2) extends into the heat-conducting barrel (3) along the axial direction of the heat-conducting barrel (3). An air outlet (20) is provided on the resistance heater (2). The wet oxygen supplied by the wet oxygen supply system enters the stirring barrel (1) through the air outlet.

2. The oxidation treatment device for preparing SiC powder particles for stirring casting according to claim 1, characterized in that: The mixing barrel (1) comprises a semi-circular barrel (11), an end seat (12) and a support shaft (13). Two semi-circular barrels (11) are provided, one end seat (12) is fixed at each end of one of the semi-circular barrels (11), two support shafts (13) are fixed to the outer sides of the end seats (12) respectively, the support shaft (13) is rotatably connected to the frame (5), and the two semi-circular barrels (11) are spliced ​​and fixed to each other to form a round barrel.

3. The oxidation treatment device for preparing SiC powder particles for stirring casting according to claim 2, characterized in that: Conical openings (111) are provided on the inner walls at both ends of the semi-circular barrel (11). After the two semi-circular barrels (11) are spliced ​​and fixed, the corresponding two conical openings (111) are spliced ​​to form a conical cavity (110).

4. The oxidation treatment device for preparing SiC powder particles for stirring casting according to claim 2, characterized in that: A plurality of vent holes are provided on the conical surface of the conical opening (111), and filter screens are laid on the vent holes. The air outlet hole (20) on the resistance heater (2) is placed in the conical cavity (110).

5. The oxidation treatment device for preparing SiC powder particles for stirring casting according to claim 4, characterized in that: The air outlet holes (20) on the resistance heater (2) are distributed at both ends of the resistance heater, and a ventilation cavity is provided in the axial direction of the resistance heater (2), the ventilation cavity is connected to the air outlet holes (20), and the ventilation cavity is used to introduce wet oxygen.

6. The oxidation treatment device for preparing SiC powder particles for stirring casting according to claim 2, characterized in that: The two half-barrels (11) are fixed together by means of a lock, and mutually matching concave surfaces and convex surfaces are provided at the joint surfaces of the two half-barrels (11).

7. The oxidation treatment device for preparing SiC powder particles for stirring casting according to claim 1, characterized in that: The inner wall of the mixing barrel is provided with mixing ribs.

8. An oxidation treatment method based on the device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1) filtering SiC powder particles to select SiC particles that meet the size range, and washing the selected SiC particles; S2) SiC powder particles and ceramic balls are added to the mixing barrel, and the resistance heater is turned on. After the mixing barrel is heated to the required temperature, the motor drives the mixing barrel to rotate to prevent the SiC powder particles from agglomerating. After the temperature continues to rise, wet oxygen is introduced for oxidation treatment; S3) After the oxidation treatment is completed, the resistance heater is turned off and the wet oxygen supply is stopped. After the temperature drops to the required temperature, the stirring barrel is stopped, and then the oxidized SiC powder particles and ceramic balls are poured out; S4) Add SiC powder particles and ceramic balls into the mixing barrel, and repeat S1) to S4) to continue preparing new SiC oxide powder particles.

9. The oxidation treatment method according to claim 8, characterized in that: In S1), the SiC powder particles are ultrasonically cleaned using a low concentration hydrochloric acid solution or water.

10. The oxidation treatment method according to claim 8, characterized in that: In S2), after the stirring barrel is heated to above 800°C, the motor drives the stirring barrel to rotate; after the temperature is raised to 1000°C, wet oxygen is introduced and oxidation treatment is performed at 1100°C, with a flow rate greater than 50 ml / min and a treatment time of 30 minutes.

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