Degassing rotor and preparation method thereof

Abstract

The invention belongs to the technical field of carbon-ceramic composite materials, and particularly relates to a degassing rotor and a preparation method thereof. The method mainly comprises the following steps that S1, a prepared workpiece is prepared, specifically, carbon felts and one-way carbon cloth are annularly and alternately laid, the layer number proportion of the one-way carbon cloth to the carbon felts is gradually decreased from the inner layer to the surface, and the prepared workpiece is prepared through needling; s2, preparing an intermediate: putting the prepared workpiece into a high-temperature furnace, introducing carbon source gas, heating the high-temperature furnace to 1000-1500 DEG C, keeping the temperature for 2-4 hours, taking out the prepared workpiece, mixing the prepared workpiece with the resin slurry, dipping the prepared workpiece into the resin slurry, vacuumizing, keeping the dipping temperature at 40-80 DEG C, keeping the vacuum for 60-180 minutes, breaking the vacuum, taking out the prepared workpiece, and curing to obtain a cured body; putting the cured body in an environment of 1000-1500 DEG C, and carrying out heat preservation for 2-4 hours to prepare an intermediate; and S3, preparation of a finished product: putting the silicon powder and the intermediate into a high-temperature furnace, and heating to 1600-1800 DEG C until the density of the finished product is greater than or equal to 1.8 g / cm < 3 >, thereby obtaining the finished product. According to the invention, the compression performance of the prepared degassing rotor can be obviously improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon ceramic composite materials, and particularly relates to a degassing rotor and a preparation method thereof. BACKGROUND

[0002] The degassing rotor is a key component in an aluminum liquid degassing device. The rotating rotor breaks the inert gas (nitrogen or argon) blown into the aluminum melt into a large number of dispersed bubbles and disperses them in the metal liquid. The bubbles absorb hydrogen and oxidized inclusions in the melt by the gas pressure difference and surface adsorption principle, and are taken out of the melt surface with the bubbles rising, so that the melt is purified. Reducing the dissolved hydrogen in the aluminum liquid to the lowest level before casting is a key factor for controlling the casting scrap rate, and the degassing rotor is an important workpiece for reducing the hydrogen content in the aluminum liquid.

[0003] Currently, graphite, SiC and SiN are mainly used for the degassing rotor. The graphite has low hardness and starts to oxidize at 400 DEG C in air. The temperature of the position where the degassing rotor contacts the aluminum liquid surface is high, and the position contacts air. Under the double actions of wear and oxidation, the graphite loses mass at a relatively high speed. The wear or deformation of the degassing rotor affects the degassing efficiency. The graphite degassing rotor is oxidized and fails after 10-20 days of use, and the degassing rotor breaks. Frequent replacement of the degassing rotor not only wastes time and effort, but also seriously affects production, causing huge economic losses. The degassing rotor made of pure SiC or SiN has good wear resistance and high-temperature oxidation resistance, but the ceramic has large brittleness, low toughness and poor thermal shock resistance. In the rotating process, the rotor is easily collided by inclusions in the aluminum liquid. The rotor falls into pieces after the collision, which easily causes the degassing rotor to be out of balance and break.

[0004] According to the working condition of the degassing rotor, the application designs a gradient structure of the carbon fiber preform, cooperates with the gas deposition and high-temperature infiltration process, so that the prepared degassing rotor has good structural characteristics and compactness, and the mechanical properties and compression performance of the degassing rotor are enhanced. SUMMARY

[0005] In order to improve the compression performance of the degassing rotor, the application aims to provide a degassing rotor and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows: A preparation method of a degassing rotor mainly includes the following steps: S1: Preparing a workpiece: A plurality of carbon felt and unidirectional carbon cloth are alternately laid in a ring shape, the layer ratio of the unidirectional carbon cloth to the carbon felt gradually decreases from the inner layer to the surface, and then the needle punching is performed along the thickness direction of the layup to obtain a prepared workpiece; S2: Preparing an intermediate body: Put the prepared workpiece into a high-temperature furnace, introduce a carbon source gas, heat the high-temperature furnace to 1000-1500℃, and keep the temperature for 2-4 hours, then take out the prepared workpiece and place it in a reaction barrel, vacuumize the reaction barrel, then inject resin slurry into the reaction barrel, so that the prepared workpiece is immersed in the resin slurry, the immersion temperature is 40-80℃, keep vacuum for 60-180 minutes, break the vacuum, take out the prepared workpiece, dry and solidify to obtain a solidified body; keep the solidified body at 1000-1500℃ for 2-4 hours to obtain an intermediate body; S3: Preparation of finished product: Put the silicon powder and the intermediate body prepared in step S2 together in a reaction at 1600-1800℃ until the density of the finished product is ≥1.8 g / cm 3 , which is obtained.

[0007] Beneficial effects: The present application is alternately laid in the carbon felt part and the unidirectional carbon cloth part, and the layer ratio of the superimposed unidirectional carbon cloth part to the carbon felt part gradually decreases from the inner layer to the surface. Because the subsequent preparation is a hollow structure inside the degassing rotor and inert gas is introduced, it is not easy to oxidize. The outer surface of the rotor is in contact with air, and the content of unidirectional carbon cloth gradually decreases from the bottom layer to the surface layer. Since the unidirectional carbon cloth has good toughness, and the carbon felt is fluffy, the setting of more unidirectional carbon cloth in the inner layer can improve the toughness of the inner part of the rotor, and thus the core layer has better load bearing capacity and better strength when the rotor is under stress. Because the external oxidation resistance is required, by increasing the content of carbon felt, the fluffy structure of carbon felt allows more ceramic matrix to be filled inside the unidirectional carbon cloth and carbon felt in the surface layer, thereby making the outer surface structure of the degassing rotor more dense and solid, and thus having better oxidation resistance and high temperature resistance, which meets the use scenario of the degassing rotor. In the subsequent intermediate body preparation, the resin slurry is mixed with the intermediate body. Part of the carbon in the resin slurry reacts at high temperature to generate a dense matrix in the intermediate body, so that the prepared intermediate body has good density and oxidation resistance. Then, through high-temperature infiltration, the silicon powder gradually melts or gasifies and contacts with the carbon in the intermediate body under the action of high temperature, and the two react to form a SiC matrix, so that the prepared degassing rotor finished product has good mechanical properties, a dense internal structure, and good compression resistance. The carbon source gas used in the present application is any one of methane or propylene.

[0008] Preferably, the laying thickness in step (1) is 10-30mm, and the needle density is (20-40) needles / cm 2 .

[0009] Beneficial effects: By determining the needle density per unit area, when the density is too low, the product will carbonize, and the relative density will increase during the high-temperature process, affecting the entry of the subsequent resin, and thus affecting the density of the finished product.

[0010] Better, the ratio of the number of layers of the unidirectional carbon cloth to the carbon felt gradually decreases from the inner layer to the surface from (4-6):1 to (0.5-1.5):1.

[0011] Beneficial effect: control the ratio of the number of layers of the unidirectional carbon cloth to the carbon felt, ensure the toughness of the prepared gas removal rotor, and also make the surface layer can combine enough ceramic matrix, the finished product of the gas removal rotor has good mechanical properties, the internal structure is dense, and the compression resistance is good.

[0012] Better, in the preparation of the intermediate in step (2), after the prepared workpiece is taken out of the high-temperature furnace, before being immersed in the resin slurry, the prepared workpiece is first placed in a vacuum barrel, vacuum is drawn, then the BN solution is injected into the vacuum barrel, vacuum immersion is performed for 30-90 min, vacuum is broken, the workpiece is taken out, and drying is performed at 70-90℃ for 2-4h.

[0013] Beneficial effect: by immersing the BN solution, when oxygen enters the matrix, BN will react with oxygen to generate B2O3 at high temperature, boron oxide is in a molten state at high temperature, can fill the internal oxygen entering channel, prevent further diffusion of oxygen to the matrix, and hinder the oxidation inside the gas removal rotor.

[0014] Better, the BN solution is configured from boron nitride powder and ethanol according to a mass ratio of 1:(5-15).

[0015] Better, before the resin slurry is injected into the reaction barrel in step S2, an active filler is added to the resin slurry, and the active filler is at least one of silicon powder and aluminum powder.

[0016] Better, the weight ratio of the active filler to the resin slurry is 1:(10-100).

[0017] Better, in the preparation of the finished product in step (3), the intermediate can also be prepared by the way of immersion-pyrolysis or chemical vapor deposition of SiC.

[0018] Better, the resin slurry is any one of furfural resin or phenolic resin.

[0019] On the other hand, the application discloses a preparation method of a gas removal rotor. A high-temperature-resistant gas removal rotor is mainly prepared by the preparation method of the gas removal rotor.

[0020] Beneficial effects: in the process of preparing the carbon ceramic composite material, the carbon felt and the unidirectional carbon cloth are alternately laid in a ring shape, the layer ratio of the carbon cloth to the carbon felt gradually transitions from 5:1 at the initial inner layer to 1:1 at the surface, and the content of the single-phase carbon cloth at the inner layer is higher than that at the surface. Since the carbon cloth has good toughness, the internal toughness can be enhanced. Since the outer part of the degassing rotor has requirements for oxidation resistance, the carbon felt has high bulkiness and more internal gaps. By reducing the ratio of the unidirectional carbon cloth to the outside, the carbon cloth and the carbon felt at the surface layer can be filled with more ceramic matrix, so that the surface structure is more dense, the ceramic matrix hinders the entry of oxygen, and at the same time, the surface has oxidation resistance and high-temperature resistance, which also reduces the oxidation loss of oxygen into the internal part of the degassing rotor, which meets the use scene of the degassing rotor. At the same time, the subsequent resin slurry and active filler cover and fill the laid carbon cloth and carbon felt, so that the structure distribution of the prepared degassing rotor is better, the mechanical properties are better, and the compression performance is improved. DETAILED DESCRIPTION

[0021] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described below in combination with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

[0022] Embodiment 1 A preparation method of a degassing rotor mainly includes the following steps: S1: preparation of a workpiece A plurality of carbon felt parts and unidirectional carbon cloth parts are alternately laid in a ring shape, the ratio of the number of unidirectional carbon cloth layers in the unidirectional carbon cloth part to the number of carbon felt layers in the carbon felt part gradually decreases from 6:1 at the inner layer to 0.5:1 at the surface, and then the unidirectional carbon cloth and the carbon felt are laid and needled in the thickness direction to obtain a prepared workpiece. The thickness of the laid unidirectional carbon cloth and carbon felt is 20 mm, and the needling density is 30 needles / cm 2 ; S2: preparation of an intermediate The prepared workpiece is placed in a high-temperature furnace, the high-temperature furnace is heated to 1250℃ and carbon source gas is introduced, and after 3h of heat preservation, the prepared workpiece is taken out and placed in a reaction barrel. The reaction barrel is sealed and vacuumized, then the resin slurry is pumped into the reaction barrel through a pipeline, so that the prepared workpiece is immersed in the resin slurry. The immersion temperature is 60℃, the vacuum preservation time is 120min, the vacuum is broken, the solidification temperature is 210℃, and the solidification time is 3h, so as to obtain a solidified body. The solidified body is placed in a pyrolysis furnace and heated to 1300℃, and then heat preserved for 3h to obtain an intermediate. The used carbon source gas is methane; the used resin slurry is furfural resin; S3: preparation of a finished product: The silicon powder and the intermediate prepared in step S2 are placed in a high-temperature-resistant sealed container and reacted at 1700°C until the final product has a density of ≥1.8 g / cm 3 Thus, the product is obtained.

[0023] Example 2 The difference between this example and Example 1 is that in the preparation of the workpiece in step S1, the ratio of the number of layers of the unidirectional carbon cloth to the number of layers of the carbon felt gradually decreases from the inner layer to the surface from 4:1 to 1.5:1; the rest are the same as in Example 1.

[0024] Example 3 The difference between this example and Example 1 is that in the preparation of the workpiece in step S1, the ratio of the number of layers of the unidirectional carbon cloth to the number of layers of the carbon felt gradually decreases from the inner layer to the surface from 5:1 to 1:1; the rest are the same as in Example 1.

[0025] Example 4 The difference between this example and Example 3 is that in the preparation of the intermediate in step S2, after the prepared workpiece is taken out of the high-temperature furnace, it is first placed in a vacuum barrel, vacuum is drawn, then BN solution is drawn into the vacuum barrel through a pipeline, so that the prepared workpiece is immersed in the BN solution, vacuum immersion is performed for 60 min, vacuum is broken, the workpiece is taken out, and drying is performed at 80°C for 3 h; the BN solution used is prepared by mixing boron nitride powder and ethanol at a mass ratio of 1:5; the rest are the same as in Example 3.

[0026] Example 5 The difference between this example and Example 4 is that in the preparation of the intermediate in step S2, the BN solution used is prepared by mixing boron nitride powder and ethanol at a mass ratio of 1:15; the rest are the same as in Example 4.

[0027] Example 6 The difference between this example and Example 4 is that in the preparation of the intermediate in step S2, the BN solution used is prepared by mixing boron nitride powder and ethanol at a mass ratio of 1:10; the rest are the same as in Example 4.

[0028] Example 7 The difference between this example and Example 6 is that in the preparation of the intermediate in step S2, before the resin slurry is drawn into the reaction barrel through a pipeline, active fillers are added to the resin slurry, and the proportion of the active fillers is 1:50 of the weight of the resin slurry; the active fillers used are silicon powder; the rest are the same as in Example 1.

[0029] Example 8 The embodiment differs from example 7 in that in the intermediate preparation in step (2), active filler is added to the resin slurry before the resin slurry is pumped into the reaction barrel, and the proportion of active filler is 1:50 of the weight of the resin slurry; the active filler used is aluminum powder; the rest is the same as in example 7.

[0030] Example 9 The embodiment differs from example 8 in that in the finished product preparation in step S3, the intermediate prepared in step S2 is immersed in a silicon carbide slurry, and impregnated under a vacuum impregnation pressure of 8 kPa for 1 h, taken out and placed in a pressure furnace, nitrogen is introduced to adjust the internal pressure of the pressure furnace to 4 MP, and impregnated for 2 h; then pyrolyzed at a high temperature of 1100℃; repeat impregnation-pyrolysis until the final product density ≥1.8 g / cm 3 ; the rest is the same as in example 8.

[0031] Comparative example 1 A method for preparing a degassing rotor mainly comprises the following steps: S1: preparation of a workpiece: The carbon felt is laid in a ring direction, and then the laid layer is needled in a thickness direction to obtain a prepared workpiece; the laid layer thickness is 20 mm, and the needling density is 30 needles / cm 2 ; S2: intermediate preparation The prepared workpiece is placed in a high-temperature furnace, a carbon source gas is introduced, the high-temperature furnace is heated to 1250℃, and after heat preservation for 3 h, the prepared workpiece is taken out and placed in a reaction barrel, the reaction barrel is sealed and vacuumized, then the resin slurry is pumped into the reaction barrel through a pipeline, so that the prepared workpiece is immersed in the resin slurry, the immersion temperature is 60℃, the vacuum is preserved for 120 min, the vacuum is broken, the solidification temperature is 210℃, and the solidification time is 3 h, to obtain a solidification body; the solidification body is placed in a pyrolysis furnace, heated to 1300℃, and heat preserved for 3 h, to obtain an intermediate; the carbon source gas used is methane; and the resin slurry used is furfural resin. S3: preparation of a finished product: The silicon powder and the intermediate prepared in step S2 are placed in a high-temperature furnace, heated to 1700℃, and reacted until the final product density ≥1.8 g / cm 3 .

[0032] Comparative example 2 The difference between the present comparative example and comparative example 1 is that in the preparation of the workpiece in step S1, the carbon felt is changed to unidirectional carbon cloth; the rest is the same as in comparative example 1.

[0033] The compression strength of the samples obtained from Examples 1-9 and Comparative Examples 1-2 was tested according to GB / T 34559-2017 Carbon-Carbon Composite Compressive Property Test Method, and recorded in Table 1 below.

[0034] Table 1

Claims

1. A method for preparing a degassing rotor, characterized in that: The main steps include the following: S1: Preliminary workpiece preparation: Multiple carbon felt sections and unidirectional carbon cloth sections are alternately laid in a circumferential direction. The carbon felt section is composed of at least one layer of carbon felt stacked and laid, and the unidirectional carbon cloth section is composed of at least one layer of unidirectional carbon cloth stacked and laid. The ratio of the number of unidirectional carbon cloth layers in the unidirectional carbon cloth section to the number of carbon felt layers in the carbon felt section gradually decreases from the inner layer to the surface. Then, needle punching is performed along the layup thickness direction to obtain the pre-workpiece. S2: Intermediate preparation: The prepared workpiece is placed in a high-temperature furnace, and a carbon source gas is introduced. The furnace is heated to 1000-1500℃ and held for 2-4 hours. The prepared workpiece is then removed and placed in a reaction vessel. The reaction vessel is evacuated, and then resin slurry is injected into the reaction vessel so that the prepared workpiece is immersed in the resin slurry. The immersion temperature is 40-80℃, and the vacuum is maintained for 60-180 minutes. The vacuum is then broken, the prepared workpiece is removed, and dried and cured to obtain a cured body. The cured body is then held at 1000-1500℃ for 2-4 hours to obtain an intermediate body. S3: Preparation of the finished product: The silicon powder and the intermediate prepared in step S2 are reacted together at 1600-1800℃ until the density of the finished product is ≥1.8 g / cm³. 3 That is, you get it.

2. The method for preparing the degassing rotor as described in claim 1, characterized in that: The layup thickness in step S1 is 10-30 mm, and the needle-punching density is 20-40 needles / cm. 2 .

3. The method for preparing the degassing rotor as described in claim 1, characterized in that: The ratio of the number of layers of the unidirectional carbon cloth part to the carbon felt part gradually decreases from (4-6):1 to (0.5-1.5):1 from the inner layer to the surface.

4. The method for preparing the degassing rotor as described in claim 2, characterized in that: In the intermediate preparation described in step S2, after the workpiece is taken out of the high-temperature furnace, before it is immersed in the resin slurry, the workpiece is placed in a vacuum barrel, a vacuum is drawn, and then the BN solution is injected into the vacuum barrel. The workpiece is then immersed in the vacuum for 30-90 minutes, the vacuum is broken, the workpiece is taken out, and dried at 70-90°C.

5. The method for preparing the degassing rotor as described in claim 4, characterized in that: The resin slurry is either furfuryl ketone resin or phenolic resin.

6. The method for preparing the degassing rotor as described in claim 4, characterized in that: The BN solution is prepared by mixing boron nitride powder and ethanol at a mass ratio of 1:(5-15).

7. The method for preparing the degassing rotor as described in claim 1, characterized in that: Before injecting the resin slurry into the reaction tank in step S2, an active filler is added to the resin slurry. The active filler is at least one of silicon powder and aluminum powder.

8. The method for preparing the degassing rotor as described in claim 7, characterized in that: The weight ratio of the active filler to the resin slurry is 1:(10-100).

9. The method for preparing the degassing rotor as described in claim 1, characterized in that: In the preparation of the finished product described in step S3, the intermediate can also be prepared by impregnation-pyrolysis or chemical vapor deposition of SiC.

10. A degassing rotor, characterized in that: It is prepared by the method of any one of claims 1-9 for the preparation of the degassing rotor.

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