CN107686380B - Preparation method of graphite rotor anti-oxidation coating for aluminum melt purification - Google Patents
Preparation method of graphite rotor anti-oxidation coating for aluminum melt purification Download PDFInfo
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- CN107686380B CN107686380B CN201710724970.XA CN201710724970A CN107686380B CN 107686380 B CN107686380 B CN 107686380B CN 201710724970 A CN201710724970 A CN 201710724970A CN 107686380 B CN107686380 B CN 107686380B
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/81—Coating or impregnation
- C04B41/89—Coating or impregnation for obtaining at least two superposed coatings having different compositions
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/52—Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
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Abstract
A preparation method of a graphite rotor anti-oxidation coating for aluminum melt purification belongs to the technical field of metal melt purification and coating protection. The preparation method comprises the following steps: firstly, carrying out pre-oxidation treatment on a graphite material to obtain a rough surface; then, immersing the graphite material with aluminum dihydrogen phosphate to improve the oxidation resistance of the graphite rotor; and finally, coating the surface layer of the graphite rotor with slurry for multiple times to ensure that the coating has a certain thickness. The method improves the oxidation resistance of the graphite rotor, prolongs the service life of the graphite rotor and improves the purification of the aluminum melt. The process is simple to operate, the raw materials are cheap and easy to obtain, and the production cost is reduced.
Description
Technical Field
The invention belongs to the technical field of metal melt purification and coating protection, and particularly relates to a preparation method of a graphite rotor anti-oxidation coating for aluminum melt purification.
Background
The rapid development of aluminum processing technology has increasingly strict requirements on the quality of aluminum products. The purification of aluminum melt and the elimination of internal defects of aluminum products are always the focus of attention in the aluminum processing industry. In the purification treatment process, the adoption of a rotary rotor to blow inert gas to remove hydrogen and oxide inclusions in molten aluminum is an international advanced molten aluminum purification technology at present.
At present, a commonly used degassing rotor is a graphite rotor, the carbon content fraction is more than 99.9%, the critical temperature of carbon oxidation in air is 400 ℃, the purification temperature of an aluminum melt is between 700 and 730 ℃, the critical temperature is greatly exceeded, the shaft diameter of a rotor shaft is gradually reduced due to graphite oxidation, and the rotor shaft is finally broken and cannot be used. Therefore, improving the oxidation resistance of the graphite material is the key to improving the purification of the aluminum melt.
The main approaches for improving the oxidation resistance of the graphite rotor are as follows: (1) high-quality and high-purity graphite is selected as a rotor material. (2) Inert gas protection method. (3) And (4) protecting the coating. (4) A sleeve protection method, etc. Among them, the paint protection method is an effective treatment method by applying paint on the surface of the graphite rotor to shield oxygen in the air and prevent the graphite rotor from being oxidized.
Disclosure of Invention
The invention provides a preparation method of a graphite rotor anti-oxidation coating for purifying an aluminum melt, aiming at improving the oxidation resistance of a graphite rotor. The method mainly comprises the following steps: firstly, carrying out pre-oxidation treatment on a graphite material to obtain a rough surface; then, immersing the graphite material with aluminum dihydrogen phosphate to improve the oxidation resistance of the graphite rotor; and finally, coating the surface layer of the graphite rotor with slurry for multiple times to ensure that the coating has a certain thickness.
The invention relates to a preparation method of a graphite rotor anti-oxidation coating for purifying an aluminum melt, which comprises the following steps:
step 1: pre-oxidation treatment of graphite
(1) Cleaning the graphite material with alcohol, drying in an oven for 5h, and cooling for 2 h;
(2) placing the cooled graphite in a high-temperature furnace at 850 ℃ for pre-oxidation for 6 min;
step 2: impregnation treatment of graphite
(1) With Al2O3Preparing aluminum dihydrogen phosphate by using the powder and phosphoric acid as raw materials;
(2) immersing the graphite material in aluminum dihydrogen phosphate, and then putting the graphite material in a vacuum pump for vacuumizing;
(3) drying the impregnated graphite material in a 120 ℃ oven for 5 hours;
and step 3: coating by brushing
(1) Using SiC powder and Al2O3The powder and the additive A are used as coating raw materials, coating slurry is prepared, and the mass fraction of the additive A in the coating raw materials is 10-40%.
(2) And after the coating slurry is uniformly mixed, coating the surface layer of the graphite rotor for multiple times, and drying or naturally airing after coating each time.
In the step 1(1), the graphite is common loose graphite;
the drying temperature of the oven is 80-150 ℃;
in the step 1(2), the high-temperature furnace is one of a box-type resistance wire furnace, a box-type silicon carbide rod furnace and a tunnel kiln;
in the step 2(1), Al as a raw material for preparing aluminum dihydrogen phosphate2O3The mass ratio of the powder to the phosphoric acid is 1: 6;
in the step 2(2), the vacuum pumping time of the vacuum pump is 5-30 min;
in the step 3(1), the additive A is Y2O3、MgO、TiO2、ZrSiO4One or more of;
in the step 3(2), the brushing times of the graphite rotor are 2-5 times;
the density of the raw materials of the coating is different, and the coating is stirred uniformly again before being brushed each time;
the painting and drying process comprises the following steps: oven drying at 100 deg.C for 1 hr, and oven drying at 200 deg.C for 1 hr.
The invention has the beneficial effects that:
1. the preparation method of the graphite rotor anti-oxidation coating for purifying the aluminum melt effectively improves the oxidation resistance of the graphite rotor, prolongs the service life of the graphite rotor and improves the purification effect of the aluminum melt.
2. According to the preparation method of the graphite rotor anti-oxidation coating for purifying the aluminum melt, the graphite rotor is subjected to dipping treatment by using the phosphate composite salt solution, so that the oxidation resistance of the graphite rotor is improved, the breaking strength is improved, and the thermal shock resistance is enhanced.
3. The preparation method of the graphite rotor anti-oxidation coating for purifying the aluminum melt adopts a coating protection method, is simple and easy in process, and is convenient for industrial production.
4. The invention relates to a preparation method of a graphite rotor anti-oxidation coating for purifying an aluminum melt, which adopts SiC powder and Al2O3The powder and the additive A are coating raw materials, the coating operation is simple, the raw materials are cheap and easy to obtain, and the production cost is greatly reduced.
Drawings
FIG. 1 is a process flow diagram of the present invention;
Detailed Description
The present invention will be described in further detail with reference to examples.
In the following examples, the starting materials are commercially available unless otherwise indicated.
In the following examples, a process flow chart of a method for improving oxidation resistance of a graphite rotor for purifying aluminum melt is shown in FIG. 1.
Example 1
A preparation method of a graphite rotor anti-oxidation coating for purifying an aluminum melt comprises the following steps:
step 1: pre-oxidation treatment of graphite
(1) Cleaning the graphite material with alcohol, drying in an oven at 120 ℃ for 5h, and cooling for 2 h;
(2) placing the cooled graphite in a high-temperature furnace at 850 ℃ for pre-oxidation for 6 min;
step 2: impregnation treatment of graphite
(1) With Al2O3Preparing aluminum dihydrogen phosphate by using the powder and phosphoric acid as raw materials;
(2) immersing the graphite material in a large beaker with aluminum dihydrogen phosphate, and putting the beaker in a vacuum pump for vacuumizing for 15 min;
(3) drying the impregnated graphite material in a 120 ℃ oven for 5 hours;
and step 3: coating by brushing
(1) Using SiC powder and Al2O3Powder and additive Y2O3Is a coating raw material. The formula consists of (mass fraction,%): 55% SiC-30% Al2O3-15％Y2O3Preparing coating slurry according to the proportion;
(2) and after the coating slurry is uniformly mixed, coating the surface layer of the graphite rotor for three times, and drying after each coating, namely drying for 1h at 100 ℃ and then drying for 1h at 200 ℃.
After the detection, the graphite rotor after coating is oxidized for 300min at 900 ℃,the mass loss is 7%, and the coating layer is kept intact; the number of thermal shock cycles from 900 ℃ to room temperature reaches 16 times; the new product phase of the coating after being oxidized for 600min at 900 ℃ is SiO2SiC component in the coating and O in air2Reaction to form SiO2The protective film reduces the peeling of the coating in the oxidation experiment process, and obviously improves the oxidation resistance of the graphite product.
Example 2
The preparation process of graphite rotor anti-oxidation coating for aluminum melt purification is the same as that in example 1, except that MgO is used as additive.
Through detection, after the graphite rotor after coating is oxidized for 300min at 900 ℃, the mass loss is 8 percent, and the coating is kept intact; the number of thermal shock cycles from 900 ℃ to room temperature reaches 12 times; the new product phase of the coating after being oxidized for 600min at 900 ℃ is SiO2SiC component in the coating and O in air2Reaction to form SiO2The protective film reduces the peeling probability of the coating in the oxidation experiment process, and obviously improves the oxidation resistance of the graphite product.
Example 3
A method for improving oxidation resistance of a graphite rotor for purifying an aluminum melt, which is the same as the method in example 1, and is characterized in that:
(1) the desired additive A is TiO2。
(2) The coating raw materials comprise the following components in percentage by mass: 45% SiC-40% Al2O3-15％TiO2。
Through detection, after the graphite rotor after coating is oxidized for 300min at 900 ℃, the mass loss is 5 percent, the coating is almost kept intact, and no large scale is generated; the thermal shock cycle number from 900 ℃ to room temperature reaches 10 times; the new product phase of the coating after being oxidized for 600min at 900 ℃ is SiO2SiC component in the coating and O in air2Reaction to form SiO2The protective film reduces the peeling probability of the coating in the oxidation experiment process, and obviously improves the oxidation resistance of the graphite product.
Example 4
A method for preparing a graphite rotor anti-oxidation coating for purifying an aluminum melt, which is the same as the embodiment 1, and is characterized in that:
(1) when the required additive A is ZrSiO4。
(2) The coating raw materials comprise the following components in percentage by mass: 45% SiC-40% Al2O3-15％ZrSiO4。
Through detection, after the graphite rotor after coating is oxidized for 300min at 900 ℃, the mass loss is 6 percent, the coating is almost kept intact, and no large scale is generated; the number of thermal shock cycles from 900 ℃ to room temperature reaches 13 times; after oxidizing for 600min at 900 ℃, SiC in the components is also reacted with O2Reaction to produce SiO2The oxidation resistance of the graphite product is obviously improved.
Claims (3)
1. A preparation method of a graphite rotor anti-oxidation coating for purifying an aluminum melt is characterized by comprising the following steps:
step 1: pre-oxidation treatment of graphite
(1) Cleaning the graphite material with alcohol, drying in an oven for 5h, and cooling for 2 h; the drying temperature of the oven is 80-150 ℃;
(2) placing the cooled graphite in a high-temperature furnace at 850 ℃ for pre-oxidation for 6 min;
step 2: impregnation treatment of graphite
(1) With Al2O3Preparing aluminum dihydrogen phosphate by using the powder and phosphoric acid as raw materials; in the step 2(1), Al2O3
The mass ratio of the powder to the phosphoric acid is 1: 6;
(2) immersing the graphite material in aluminum dihydrogen phosphate, and then putting the graphite material in a vacuum pump for vacuumizing;
(3) drying the impregnated graphite material in a 120 ℃ oven for 5 hours;
and step 3: coating by brushing
(1) 45% by mass of SiC powder and Al2O3Coating raw materials comprising 40% of powder and 15% of additive A in percentage by mass are prepared into coating slurry;
(2) after the coating slurry is uniformly mixed, coating the surface layer of the graphite rotor for 2-5 times, and drying or naturally airing after coating each time; the painting and drying process comprises the following steps: drying at 100 deg.C for 1h, and drying at 200 deg.C for 1 h;
the additive A is Y2O3、MgO、TiO2、ZrSiO4One or more of;
in the step 1, the graphite is loose graphite.
2. The method of claim 1, wherein in step 1(2), the high temperature furnace is one of a box-type resistance wire furnace, a box-type silicon carbide rod furnace and a tunnel kiln.
3. The method according to claim 1, wherein in the step 2(2), the vacuum pump is vacuumized for 5-30 min.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108456005B (en) * | 2018-04-20 | 2021-04-27 | 郑州大学 | Graphite oxidation resistant coating |
| CN111362727B (en) * | 2020-03-18 | 2022-05-10 | 德翼高科(杭州)科技有限公司 | Phosphate anti-oxidation coating of carbon/carbon composite material and coating process thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19652670C1 (en) * | 1996-12-18 | 1998-02-05 | Meierkord Karl Heinz | Electric furnace for maintaining metal in molten state |
| CN201864764U (en) * | 2010-11-10 | 2011-06-15 | 王丽珍 | Graphite rotor used in aluminum liquid degasser |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19652670C1 (en) * | 1996-12-18 | 1998-02-05 | Meierkord Karl Heinz | Electric furnace for maintaining metal in molten state |
| CN201864764U (en) * | 2010-11-10 | 2011-06-15 | 王丽珍 | Graphite rotor used in aluminum liquid degasser |
Non-Patent Citations (2)
| Title |
|---|
| 涂层法提高石墨转子抗氧化性能的研究;陈寒玉等;《炭素技术》;20080415;第27卷(第2期);第30页左栏第4-6行，第31页左栏1.2第1-14行，右栏2-8行和2.2第6-9行，第32页右栏第5-9行 * |
| 铝液除气机中的石墨转子强化工艺研究;王丽珍;《新技术新工艺》;20120325(第3期);第56右栏1.1第1-11行，1.2第1-5行，第32页右栏第5-9行，第57页左栏2第1-5，3第1-7行 * |
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