阅读说明：本技术 升液管保温涂层结构及制备方法 (Heat-insulating coating structure of lift tube and preparation method ) 是由 刘凯 李秋南 王惠民 许斌 吴急涛 夏志强 赵红飞 黄涛 童捷 赵涛 于 2020-03-30 设计创作，主要内容包括：本发明提出了一种升液管保温涂层结构,通过在升液管复内壁面的保温层以及涂覆于保温层表面的致密层,不仅具有良好的保温效果,防止升液管的上部容易出现铝液结渣,同时该保温涂层具有良好的防粘铝效果；本发明的升液管保温涂层结构,保温层以氧化铝粉、纤维棉、高岭土、莫来石粉为原料,从而使得制得的保温层导热系数低,保温效果好；该保温层中还有树胶,具体为桃胶,并对桃胶进行预处理,具体为先于石油醚与丙酮的混合溶剂中,再加入三聚磷酸钠、二乙烯三胺反应,然后加入甲基丙烯酸反应即完成预处理,处理后的桃胶可进一步降低导热系数,提高保温效果。(The invention provides a heat-insulating coating structure of a lift tube, which has a good heat-insulating effect by virtue of a heat-insulating layer on the inner wall surface of the lift tube and a compact layer coated on the surface of the heat-insulating layer, so that molten aluminum is prevented from being easily slagging on the upper part of the lift tube, and meanwhile, the heat-insulating coating has a good aluminum adhesion preventing effect; according to the heat-insulating coating structure of the lift tube, the heat-insulating layer takes alumina powder, cellucotton, kaolin and mullite powder as raw materials, so that the prepared heat-insulating layer is low in heat conductivity coefficient and good in heat-insulating effect; the heat-insulating layer is also internally provided with gum, specifically peach gum, and the peach gum is pretreated, specifically, firstly, in a mixed solvent of petroleum ether and acetone, sodium tripolyphosphate and diethylenetriamine are added for reaction, then, methacrylic acid is added for reaction, so that the pretreatment is completed, the treated peach gum can further reduce the heat conductivity coefficient, and the heat-insulating effect is improved.)

1. The utility model provides a stalk insulation coating structure which characterized in that: comprises a heat-insulating layer coated on the inner wall surface of the silicon nitride ceramic lift tube and a compact layer coated on the surface of the heat-insulating layer;

wherein the heat-insulating layer comprises alumina powder, cellucotton, kaolin, mullite powder, sodium carboxymethylcellulose, gum, polypropylene staple fiber and wollastonite; the dense layer comprises boron nitride, aluminum nitride, zirconium silicate, silica sol, lignin fiber and glass fiber.

2. The lift tube thermal coating structure of claim 1, wherein: the mass ratio of alumina powder, cellucotton, kaolin, mullite powder, sodium carboxymethylcellulose, gum, polypropylene short fibers and wollastonite in the heat-insulating layer is 60-80: 12-18: 4-6: 12-16: 3-8: 1-3: 10-15; the mass ratio of boron nitride, aluminum nitride, zirconium silicate, silica sol, lignocellulose and glass fiber in the compact layer is 25-30: 20-25: 10-15: 2-6: 3-6: 1-3.

3. The lift tube thermal coating structure of claim 1, wherein: the thickness of the heat preservation layer is 5-10 mm, and the thickness of the compact layer is 0.5-1 mm.

4. A method for preparing a riser tube insulation coating structure according to any one of claims 1 to 3, which is characterized in that: preparing a heat-insulating layer, which comprises the following steps:

s1, polishing the inner wall of the silicon carbide ceramic lift tube;

s2, placing alumina powder, kaolin, mullite powder and wollastonite in an acetic acid solution, soaking for 2-4 hours, filtering to obtain a filtrate, mixing the filtrate with cellucotton, polypropylene short fibers and sodium carboxymethylcellulose, ball-milling for 2-4 hours, adding gum and water, and continuing ball-milling for 3-6 hours to obtain a ball-milled product;

s3, coating the ball mill matter on the inner wall of the silicon carbide ceramic riser, and drying for 8-16 h at the temperature of 60-120 ℃ to obtain a heat-insulating layer;

preparing a compact layer on the surface of the heat preservation layer, which comprises the following steps:

a1, mixing boron nitride, aluminum nitride and zirconium silicate, ball-milling for 1-3 h, adding silica sol, continuing ball-milling, coating the materials on the surface of the heat-insulating layer after ball-milling, and drying at the temperature of 60-120 ℃ for 8-16 h;

and A2, mixing the lignocellulose and the glass fiber, adding silica sol, performing ball milling for 3-8 hours, coating the mixture on the surface of the heat-preservation coating formed in A1 after ball milling, and drying the mixture for 8-16 hours at the temperature of 60-120 ℃ to obtain the compact layer.

5. The method of making a lift tube thermal coating structure of claim 4, wherein: before the compact layer is prepared, the prepared heat preservation layer is soaked in tartaric acid, malic acid and caffeic acid solution for 5-10 min.

6. The method of making a lift tube thermal coating structure of claim 4, wherein: the gum in the S2 is peach gum, and the pretreatment of the peach gum is carried out before adding the peach gum, wherein the pretreatment specifically comprises the following steps: dissolving peach gum powder in a mixed solvent of petroleum ether and acetone, adding sodium tripolyphosphate and diethylenetriamine, reacting at the temperature of 30-40 ℃ for 1-3 h, then continuously adding methacrylic acid, heating to 50-60 ℃, continuously reacting for 4-6 h, filtering, and drying to finish peach gum pretreatment.

7. The method of making a lift tube thermal coating structure of claim 4, wherein: and (8) after the filtrate is obtained in S2, treating the filtrate for 0.5-1 h by using a silane coupling agent.

8. The method for preparing the heat-insulating coating structure for the lift tube of claim 7, wherein the silane coupling agent is a mixture of a silane coupling agent KH-550, a silane coupling agent KH-560 and a silane coupling agent D L-602.

9. The method of making a lift tube thermal coating structure of claim 4, wherein: the diameter of the lignocellulose is 20-120 nm, the length-diameter ratio is 400-600, and the content of the lignin is 20-40 wt%.

10. The preparation method of the heat-insulating coating structure for the lift tube according to claim 8, wherein the mass ratio of the silane coupling agent KH550 to the silane coupling agent KH 560 to the silane coupling agent D L602 is 1-3: 2-4: 3-6.

Technical Field

The invention relates to the technical field of coatings, in particular to a heat-insulating coating structure of a lift tube and a preparation method thereof.

Background

The liquid lifting pipe is one of key parts on the low-pressure casting machine of the aluminum alloy, and is placed in a heat preservation furnace which is sealed and filled with aluminum liquid of the low-pressure casting machine during working, and aluminum melt (about 700 plus 900 ℃) is forced to move upwards along the liquid lifting pipe by certain air pressure, so that the filling and feeding of the aluminum liquid are realized. And the pressure of 0.08-0.1 MPa is required to be kept in the aluminum liquid mold filling process. Therefore, the lift tube is required to have good air tightness, high temperature resistance, thermal shock resistance and aluminum liquid corrosion resistance, and also to have long-term thermal shock fatigue resistance.

Silicon carbide ceramic is an ideal material for preparing the lift tube, but the heat-conducting property of the lift tube made of the silicon carbide ceramic is good, so that the heat-insulating property is poor, molten aluminum is easy to slag on the upper part of the lift tube in the molten aluminum mold filling process, the actual channel of the lift tube is reduced, and the mold filling and feeding effects are influenced. Improvements in riser tubes are therefore desirable.

Disclosure of Invention

In view of the above, the invention provides a heat preservation coating structure for a lift tube, which has a good heat preservation effect and a good aluminum adhesion prevention effect.

The technical scheme of the invention is realized as follows: the invention provides a silicon carbide ceramic lift tube composite heat-insulating coating, which comprises a heat-insulating layer coated on the inner wall surface of a silicon nitride ceramic lift tube and a compact layer coated on the surface of the heat-insulating layer;

wherein the heat-insulating layer comprises alumina powder, cellucotton, kaolin, mullite powder, sodium carboxymethylcellulose, gum, polypropylene staple fiber and wollastonite; the dense layer comprises boron nitride, aluminum nitride, zirconium silicate, silica sol, lignin fiber and glass fiber.

On the basis of the technical scheme, the preferable mass ratio of the alumina powder, the cellucotton, the kaolin, the mullite powder, the sodium carboxymethylcellulose, the gum, the polypropylene staple fiber and the wollastonite in the heat-insulating layer is 60-80: 12-18: 4-6: 12-16: 3-8: 1-3: 10-15; the mass ratio of boron nitride, aluminum nitride, zirconium silicate, silica sol, lignocellulose and glass fiber in the compact layer is 25-30: 20-25: 10-15: 2-6: 3-6: 1-3.

On the basis of the technical scheme, the thickness of the heat-insulating layer is preferably 5-10 mm, and the thickness of the compact layer is preferably 0.5-1 mm.

The invention also provides a preparation method of the heat-insulating coating structure of the lift tube, which is used for preparing the heat-insulating layer and comprises the following steps:

s1, polishing the inner wall of the silicon carbide ceramic lift tube;

s2, placing alumina powder, kaolin, mullite powder and wollastonite in an acetic acid solution, soaking for 2-4 hours, filtering to obtain a filtrate, mixing the filtrate with cellucotton, polypropylene short fibers and sodium carboxymethylcellulose, ball-milling for 2-4 hours, adding gum and water, and continuing ball-milling for 3-6 hours to obtain a ball-milled product;

s3, coating the ball mill matter on the inner wall of the silicon carbide ceramic riser, and drying for 8-16 h at the temperature of 60-120 ℃ to obtain a heat-insulating layer;

preparing a compact layer on the surface of the heat preservation layer, which comprises the following steps:

a1, mixing boron nitride, aluminum nitride and zirconium silicate, ball-milling for 1-3 h, adding silica sol, continuing ball-milling, coating the materials on the surface of the heat-insulating layer after ball-milling, and drying at the temperature of 60-120 ℃ for 8-16 h;

and A2, mixing the lignocellulose and the glass fiber, adding silica sol, performing ball milling for 3-8 hours, coating the mixture on the surface of the heat-preservation coating formed in A1 after ball milling, and drying the mixture for 8-16 hours at the temperature of 60-120 ℃ to obtain the compact layer.

On the basis of the technical scheme, preferably, before the dense layer is prepared, the prepared heat preservation layer is further soaked in tartaric acid, malic acid and caffeic acid solution for 5-10 min.

On the basis of the above technical scheme, preferably, the gum in S2 is peach gum, and the pretreatment of the peach gum before adding the peach gum is specifically: dissolving peach gum powder in a mixed solvent of petroleum ether and acetone, adding sodium tripolyphosphate and diethylenetriamine, reacting at the temperature of 30-40 ℃ for 1-3 h, then continuously adding methacrylic acid, heating to 50-60 ℃, continuously reacting for 4-6 h, filtering, and drying to finish peach gum pretreatment.

On the basis of the technical scheme, preferably, the filtrate obtained in S2 is treated with a silane coupling agent for 0.5-1 h.

Further preferably, the silane coupling agent is a mixture of a silane coupling agent KH-550, a silane coupling agent KH-560 and a silane coupling agent D L-602.

On the basis of the technical scheme, preferably, the diameter of the lignocellulose is 20-120 nm, the length-diameter ratio is 400-600, and the content of the lignin is 20-40 wt%.

More preferably, the mass ratio of the silane coupling agent KH550 to the silane coupling agent KH 560 to the silane coupling agent D L602 is 1-3: 2-4: 3-6.

Compared with the prior art, the heat-insulating coating structure of the lift tube has the following beneficial effects:

(1) according to the heat-insulating coating structure of the lift tube, the heat-insulating layer on the inner wall surface of the lift tube and the compact layer coated on the surface of the heat-insulating layer have good heat-insulating effect, molten aluminum slagging on the upper part of the lift tube is prevented, and meanwhile, the heat-insulating coating has good aluminum adhesion preventing effect;

(2) according to the heat-insulating coating structure of the lift tube, the heat-insulating layer takes alumina powder, cellucotton, kaolin and mullite powder as raw materials, so that the prepared heat-insulating layer is low in heat conductivity coefficient and good in heat-insulating effect; the heat-insulating layer is also internally provided with gum, specifically peach gum, and the peach gum is pretreated, specifically, firstly, in a mixed solvent of petroleum ether and acetone, sodium tripolyphosphate and diethylenetriamine are added for reaction, then, methacrylic acid is added for reaction, so that the pretreatment is completed, the treated peach gum can further reduce the heat conductivity coefficient, and the heat-insulating effect is improved;

(3) according to the heat-insulating coating structure of the lift tube, the compact layer takes boron nitride and aluminum nitride as raw materials, and the wettability of the boron nitride, the aluminum nitride and aluminum liquid is extremely poor, so that the heat-insulating coating structure has good aluminum liquid corrosion resistance; meanwhile, in the preparation process, firstly, boron nitride, aluminum nitride and the like are dried after ball milling, then, the coated lignocellulose and glass fiber are dried again to obtain a compact layer, and the lignocellulose and the glass fiber can be filled in gaps to further improve the density of the heat-insulating coating, so that the heat-insulating coating is smoother, and the aluminum liquid corrosion resistance of the heat-insulating coating is further improved;

(4) according to the heat-insulating coating structure of the lift tube, before the compact layer is prepared, the prepared heat-insulating layer is soaked in the tartaric acid, malic acid and caffeic acid solution, and the binding force between the heat-insulating layer and the compact layer can be further improved after soaking.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.