Riser Tube Coating for Cast Aluminum Alloy and Using Method Thereof

Abstract

A riser tube coating for a cast aluminum alloy includes a coating-riser tube contact layer material and a coating-aluminum liquid contact layer material. The present invention has a coating protection effect to the maximum mainly by designing ratios of ZrO, Al.sub.2O.sub.3, ZnO, binders and other materials and a coat drying heat treatment process, and finally realizes effects of protecting a riser tube, being free of aluminum sticking and prolonging a service life.

Claims

1. A riser tube coating for a cast aluminum alloy, characterized by comprising a coating-riser tube contact layer material and a coating-aluminum liquid contact layer material, wherein the coating-riser tube contact layer material comprises ZrO.sub.2, Al.sub.2O.sub.3, ZnO and a binder, ZrO.sub.2 accounts for 70%-80%, Al.sub.2O.sub.3 accounts for 10%-15%, ZnO accounts for 10%-15%, and a weight ratio of the binder to the materials is 10:1; and the coating-aluminum liquid contact layer material is mainly ZrO.sub.2, Al.sub.2O.sub.3, ZnO and a binder, in the coating-aluminum liquid contact layer material, the ZrO.sub.2 accounts for 80%-90%, Al.sub.2O.sub.3 accounts for 5%-10%, ZnO accounts for 5%-10%, and a weight ratio of the binder to the materials is 15:1.

2. The riser tube coating for the cast aluminum alloy according to claim 1, characterized in that ZrO.sub.2 in the coating-riser tube contact layer material is of a particle structure, a particle size is 50 μm-70 μm, Al.sub.2O.sub.3 is of a particle structure, a particle size is 40 μm-60 μm, ZnO is of a particle structure, and a particle size is 40 μm-60 μm.

3. The riser tube coating for the cast aluminum alloy according to claim 2, characterized in that a thickness of the coating-riser tube contact layer material is 0.5 mm-1.0 mm.

4. The riser tube coating for the cast aluminum alloy according to claim 1, characterized in that ZrO.sub.2 in the coating-aluminum liquid contact layer material is of a particle structure, a particle size is 30 μm-50 μm, Al.sub.2O.sub.3 is of a particle structure, a particle size is 20 μm-30 μm, ZnO is of a particle structure, and a particle size is 20 μm-30 μm.

5. The riser tube coating for the cast aluminum alloy according to claim 4, characterized in that a thickness of the coating-aluminum liquid contact layer material is 1.0 mm-1.5 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Accompanying drawings forming part of the present invention are used to provide further understanding of the present invention, and schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute undue limitation to the present invention. In the accompanying drawings:

[0028] FIG. 1 is a schematic diagram of a riser tube coating for a cast aluminum alloy of the present invention.

DETAILED DESCRIPTION

[0029] It should be noted that embodiments and features in the embodiments of the present invention may be combined with each other without conflict. The technical solution of the present invention is clearly and completely described below in combination with FIG. 1 and embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by those ordinarily skilled in the art on the basis of the embodiments in the present invention without creative labor fall within the scope of protection of the present invention.

[0030] A riser tube coating for a cast aluminum alloy and a using method thereof of

[0031] the embodiments of the present invention are described below in combination with the embodiments. Materials of the coating are mainly ZrO.sub.2, Al.sub.2O.sub.3, ZnO, a binder and so on. The present invention has a protection effect on the coating to the maximum mainly by designing ratios of ZrO, Al.sub.2O.sub.3, ZnO, the binder and other materials and a coat drying heat treatment process, and finally realizes effects of protecting a riser tube, being free of aluminum sticking and prolonging the service life. The coating has significant effects of being protective, being free of aluminum sticking and prolonging life of a riser tube and is an environmentally-friendly coating with good protectiveness.

EMBODIMENT 1

[0032] Embodiments of the present invention provide a riser tube coating for a cast aluminum alloy and a using method thereof. A coating material is mainly composed of ZrO.sub.2, Al.sub.2O.sub.3, ZnO and a binder, and proportions of which are weight percentages.

[0033] A coating-riser tube contact layer material is mainly ZrO.sub.2, Al.sub.2O.sub.3, ZnO and a binder, ZrO.sub.2 is of a particle structure, a particle size is 50 μm, Al.sub.2O.sub.3 is of a particle structure, a particle size is 40 μm, ZnO is of a particle structure, and a particle size is 40 μm. In a coating-riser tube contact layer, ZrO.sub.2 accounts for 70%, Al.sub.2O.sub.3 accounts for 15%, ZnO accounts for 15%, a weight ratio of the binder to the materials is 10:1, and a painting thickness of the whole coating-riser tube contact layer is required to be 0.5 mm.

[0034] The above specified materials are put into a mixing bucket for preliminary mixing, a rotation speed of a mixer is 200 revolutions per minute to obtain a preliminarily-mixed material, then, the obtained preliminarily-mixed material is rapidly mixed, the binder needs to be added in a rapid mixing stage, the weight ratio of the binder to the materials is 10:1, the rotation speed of the mixer is 300 revolutions per minute to obtain a coating-riser tube contact layer coating, the coating is used for painting the riser tube, and a coating thickness is 0.5 mm.

[0035] A coating-aluminum liquid contact layer material is mainly ZrO.sub.2, Al.sub.2O.sub.3, ZnO and a binder, ZrO.sub.2 is of a particle structure, a particle size is 30 μm, Al.sub.2O.sub.3 is of a particle structure, a particle size is 20 μm, ZnO is of a particle structure, and a particle size is 20 μm. In a coating-aluminum liquid contact layer, ZrO.sub.2 accounts for 80%, Al.sub.2O.sub.3 accounts for 10%, ZnO accounts for 10%, a weight ratio of the binder to the materials is 15:1, and a painting thickness of the whole coating-aluminum liquid contact layer is required to be 1.0 mm.

[0036] The above specified materials are put into the mixing bucket for preliminary mixing, the rotation speed of the mixer is 200 revolutions per minute to obtain a preliminarily-mixed material, then, the obtained preliminarily-mixed material is quickly mixed, the binder needs to be added in a rapid mixing stage, the weight ratio of the binder to the materials is 15:1, the rotation speed of the mixer is 300 revolutions per minute to obtain a coating-aluminum liquid contact layer coating, the coating is used for painting the riser tube, and a coating thickness is 1.0 mm.

[0037] After coating painting of the coating-riser tube contact layer and the coating-aluminum liquid contact layer is finished, the riser tube is dried for 2h and then placed in a warm box for heating. Drying is mainly divided into two stages, parameters of a first-stage drying heat treatment process are holding temperature being 250° C. and holding time being 6 h. Parameters of a second-stage drying heat treatment process are holding temperature being 300° C. and holding time being 3 h. A riser tube with a coating coverage layer is finally obtained.

EMBODIMENT 2

[0038] Embodiments of the present invention provide a riser tube coating for a cast aluminum alloy and a using method thereof. A coating material is mainly composed of ZrO.sub.2, Al.sub.2O.sub.3, ZnO and a binder, and proportions of which are weight percentages.

[0039] A coating-riser tube contact layer material is mainly ZrO.sub.2 , Al.sub.2O.sub.3, ZnO and a binder, ZrO.sub.2 is of a particle structure, a particle size is 70 μm, Al.sub.2O.sub.3 is of a particle structure, a particle size is 60 μm, ZnO is of a particle structure, and a particle size is 60 μm. In a coating-riser tube contact layer, ZrO.sub.2 accounts for 80%, Al.sub.2O.sub.3 accounts for 10%, ZnO accounts for 10%, a weight ratio of the binder to the materials is 10:1, and a painting thickness of the whole coating-riser tube contact layer is required to be 1.0 mm.

[0040] The above specified materials are put into a mixing bucket for preliminary mixing, a rotation speed of a mixer is 200 revolutions per minute to obtain a preliminarily-mixed material, then, the obtained preliminarily-mixed material is rapidly mixed, the binder needs to be added in a rapid mixing stage, the weight ratio of the binder to these materials is 10:1, the rotation speed of the mixer is 300 revolutions per minute to obtain a coating-riser tube contact layer coating, the coating is used for painting the riser tube, and a coating thickness is 1.0 mm.

[0041] A coating-aluminum liquid contact layer material is mainly ZrO.sub.2, Al.sub.2O.sub.3, ZnO and a binder, ZrO.sub.2 is of a particle structure, a particle size is 50 μm, Al.sub.2O.sub.3 is of a particle structure, a particle size is 30 μm, ZnO is of a particle structure, and a particle size is 30 μm. In a coating-aluminum liquid contact layer, ZrO.sub.2 accounts for 90%, Al.sub.2O.sub.3 accounts for 5%, ZnO accounts for 5%, a weight ratio of the binder to the materials is 15:1, and a painting thickness of the whole coating-riser tube contact layer is required to be 1.5 mm.

[0042] The above specified materials are put into the mixing bucket for preliminary mixing, the rotation speed of the mixer is 200 revolutions per minute to obtain a preliminarily-mixed material, then, the obtained preliminarily-mixed material is rapidly mixed, the binder needs to be added in a rapid mixing stage, the weight ratio of the binder to the materials is 15:1, the rotation speed of the mixer is 300 revolutions per minute to obtain a coating-aluminum liquid contact layer coating, the coating is used for painting the riser tube, and a coating thickness is 1.5 mm.

[0043] After coating painting of the coating-riser tube contact layer and the coating-aluminum liquid contact layer is finished, the riser tube is dried for 2 h and then placed in the warm box for heating. Drying is mainly divided into two stages, parameters of a first-stage drying heat treatment process are holding temperature being 350° C. and holding time being 5 h. Parameters of a second-stage drying heat treatment process are holding temperature being 400° C. and holding time being 2 h. A riser tube with a coating coverage layer is finally obtained.

EMBODIMENT 3

[0044] Embodiments of the present invention provide a riser tube coating for a cast aluminum alloy and a using method thereof. A coating material is mainly composed of ZrO.sub.2, Al.sub.2O.sub.3, ZnO and a binder, and proportions of which are weight percentages. A coating-riser tube contact layer material is mainly ZrO.sub.2, Al.sub.2O.sub.3, ZnO and a binder, ZrO.sub.2 is of a particle structure, a particle size is 60 μm, Al.sub.2O.sub.3 is of a particle structure, a particle size is 50 μm, ZnO is of a particle structure, and a particle size is 50 μm. In a coating-riser tube contact layer, ZrO.sub.2 accounts for 75%, Al.sub.2O.sub.3 accounts for 13%, ZnO accounts for 12%, a weight ratio of the binder to the materials is 10:1, and a painting thickness of the whole coating-riser tube contact layer is required to be 0.8 mm. The above specified materials are put into a mixing bucket for preliminary

[0045] mixing, a rotation speed of a mixer is 200 revolutions per minute to obtain a preliminarily-mixed material, then, the obtained preliminarily-mixed material is rapidly mixed, the binder needs to be added in a rapid mixing stage, the weight ratio of the binder to the materials is 10:1, the rotation speed of the mixer is 300 revolutions per minute to obtain a coating-riser tube contact layer coating, the coating is used for painting the riser tube, and a coating thickness is 0.8 mm.

[0046] A coating-aluminum liquid contact layer material is mainly ZrO.sub.2, Al.sub.2O.sub.3, ZnO and a binder, ZrO.sub.2 is of a particle structure, a particle size is 40 μm, Al.sub.2O.sub.3 is of a particle structure, a particle size is 25 μm, ZnO is of a particle structure, and a particle size is 28 μm. In a coating-aluminum liquid contact layer, ZrO.sub.2 accounts for 85%, Al.sub.2O.sub.3 accounts for 8%, ZnO accounts for 7%, a weight ratio of the binder to the materials is 15:1, and a painting thickness of the whole coating-riser tube contact layer is required to be 1.2 mm.

[0047] The above specified materials are put into the mixing bucket for preliminary mixing, a rotation speed of the mixer is 200 revolutions per minute to obtain a preliminarily-mixed material, then, the obtained preliminarily-mixed material is rapidly mixed, the binder needs to be added in a rapid mixing stage, the weight ratio of the binder to the materials is 15:1, the rotation speed of the mixer is 300 revolutions per minute to obtain a coating-aluminum liquid contact layer coating, the coating is used for painting the riser tube, and a coating thickness is 1.2 mm.

[0048] After coating painting of the coating-riser tube contact layer and the coating-aluminum liquid contact layer is finished, the riser tube is dried for 2 h and then placed in the warm box for heating. Drying is mainly divided into two stages, parameters of the first-stage drying heat treatment process are holding temperature being 300° C. and holding time being 5.5 h. Parameters of the second-stage drying heat treatment process are holding temperature being 350° C. and holding time being 2.5 h. A riser tube with a coating coverage layer is finally obtained.

TABLE-US-00001 TABLE 1 normal riser tube and embodiment data comparison table Replacement Comparison Accumulated Aluminum and cleaning Cleaning data service life sticking weight frequency time Normal riser  60 days 2.81 Kg  5 days/time 2.1 h tube Embodiment 112 days 0.41 Kg 10 days/time  32 min 1 Embodiment 110 days 0.39 Kg 12 days/time  30 min 2 Embodiment 112 days 0.40 Kg 11 days/time  32 min 3

[0049] Statistics are performed on comparison data between a normal riser tube and the embodiments in the Table 1 above. It can be seen from Table 1 that the normal riser tube has a short accumulated service life, a large aluminum sticking weight, a high replacement and cleaning frequency and difficulty cleaning, while the accumulated service life, the aluminum sticking weight, the replacement and cleaning frequency and cleaning time of the Embodiment 1, the Embodiment 2 and the Embodiment 3 have been greatly improved. Thus, it may be illustrated that that the coating and the using method of the coating of the present invention can prolong the service life of the riser tube, reduce the aluminum sticking on the inner wall, reduce the replacement frequency, and reduce the cleaning difficulty and time. Therefore, the present invention has the advantages of having good protectiveness for the riser tube, being free of aluminum sticking, prolonging the service life, and being environmentally-friendly.

[0050] Compared with the prior art, the riser tube coating for the cast aluminum alloy and the using method thereof of the present invention have the following advantages: [0051] at present, in the production process of antigravity casting of the cast aluminum alloy, the high temperature metal liquid in the crucible or holding furnace enters the mold cavity through the riser tube under the action of the gas pressure, the metal liquid stays in the riser tube for the period of time in the pressure maintaining stage, and with the pressure relief of the gas in the crucible or the holding furnace, the metal liquid in the riser tube will flow into the crucible or the holding furnace again. The metal liquid enters the riser tube, and forms thermal impact on the inner wall of the riser tube, which easily causes cracking and thermal erosion of the riser tube. In this process, the interface of the riser tube and the metal liquid is seriously eroded, and part of the riser tube material will fall and enter the metal liquid; then the high temperature metal liquid is oxidized due to making contact with the air, and stuck to the inner wall and the outer wall of the riser tube, resulting in reduction of the life of the riser tube; and once again, the slag inclusions inside the high-temperature molten metal are easily bonded to the inner wall of the riser tube due to repeated scouring in the riser tube. Because the metal liquid reacts in a high-temperature situation and forms aluminum sticking, subsequent cleaning of the riser tube needs high-temperature baking, cleaning is very difficult, and labor intensity and production cost are seriously increased. For solving the above problems, the present invention provides the riser tube coating resistant to high temperature, resistant to thermal impact, free of aluminum sticking, good in protection, capable of prolonging the life and environmentally-friendly.

[0052] (1), ZrO.sub.2, Al.sub.2O.sub.3, ZnO, the binder and other materials used in the present invention have a high melting point and are easily prepared into the coating. Through design of parameters such as a shape, a size and a proportion of the materials, it can be ensured that the coating has a protective effect on the riser tube. According to the statistics, under the current production process conditions, a riser tube without the coating needs to be disassembled and cleaned every 5 days, and the accumulated service life is about 60 days. However, the riser tube treated by the coating and a baking method designed by the present invention should be cleaned after 10 days, the coating is painted again, and the accumulated service life can reach 110 days. After calculating the price and life of the riser tube used by the factory, the monthly cost of the riser tube can be saved by about 48,000 yuan. Therefore, it can be illustrated that the present invention has good protection, life prolonging and cost saving effects on the riser tube.

[0053] (2), by applying the coating designed in the present invention to brush the riser tube and performing baking according to the baking process, inner wall slag hanging of the riser tube can be effectively reduced, and the removal of the inner wall hanging slag does not require high temperature heating, so as to greatly improve the working environment and reduce labor intensity. By comparing an aluminum sticking weight of the riser tube without using the coating with that of the riser tube using the coating of the present invention, it may be found that the weight of the riser tube without using the coating is increased by about 2.8 Kg when scrapped, and the weight of the riser tube using the coating of the present invention is increased by 0.4 Kg when scrapped. Accordingly, it may be seen that the coating of the present invention can prevent the aluminum slag from sticking in the inside of the riser tube and reduce the mass loss of the aluminum liquid. There is a difference in cleaning time between the riser tube without using the coating and the riser tube using the coating of the present invention. The riser tube without using the coating needs to be roasted at a high temperature for 4 h and cleaned for 2 h. The riser tube using the coating of the present invention does not need high temperature baking in the cleaning process, and the cleaning time is 30 min. Therefore, the coating designed by the present invention can achieve the effects of being free of aluminum sticking on the inner wall of the riser tube, reducing slagging, saving cost and being environmentally friendly.

[0054] (3), the materials in the coating designed in the present invention and a device used in the baking process are conventional materials. The production process of the refractory materials is mature and stable, so the cost of the riser tube will not be increased. Therefore, the present invention has the advantages of easy realization, economy and practicality.

[0055] In the descriptions of the present invention, it needs to be understood that an orientation or position relationship indicated by terms “center”, “longitudinal”, “transverse”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, etc. does not indicate or imply that a referred apparatus or element must have a particular orientation or be constructed and operated for the particular orientation, and therefore, it cannot be understood as the limitation to the protection content of the present invention.

[0056] Furthermore, terms “first” and “second” are merely used for descripting purposes and are not to be understood as indicating or implying relative importance or as implicitly indicating the number of technical features indicated. Thus, a feature defined as “first” or “second” may explicitly or implicitly include one or more the features. In the description of the present invention, “a plurality of” means at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0057] In the present invention, unless otherwise clearly specified and limited, terms “installation”, “connection”, “link”, “fixing”, etc. shall be understood broadly, for example, may be fixed connection, may also be detachable connection, or may be integrated connection; may be mechanical connection, may also be electric connection or may be intercommunication; and may be direct connection, may also be indirect connection through an intermediation, and may be communication inside two elements or an interaction relation of two elements. For those ordinarily skilled in the art, the specific meanings of the above terms in the present invention may be understood according to the specific circumstances.

[0058] The above is only an exemplary embodiment of the present invention and is not used to limit the present invention. Any modification, equivalent substitution, improvement, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.