A super-long plate-shaped heat-resistant steel ingot release coating and preparation method thereof

Abstract

The present invention discloses a demoulding coating for super-long plate-shaped heat-resistant steel ingots and a preparation method thereof. The coating components are proportioned as follows by mass: 50 to 120 parts of refractory aggregate, 80 to 210 parts of carrier, 3 to 6 parts of suspending agent, 5 to 15 parts of binder, and 0.5 to 3 parts of active agent. The preparation method comprises grinding and mixing the refractory aggregate, modulating the carrier, modulating the suspending agent, and modulating the binder. After the refractory aggregate and the binder are evenly mixed, they are added into the carrier. During this period, the modulated paste suspending agent and active agent are added into the carrier in batches and continuously stirred. The stirring time is greater than 3 hours to ensure that the various components of the coating are fully mixed. The demoulding coating product for heat-resistant steel ingots provided by the present invention can effectively solve the production problems such as the difficulty in demoulding of existing coatings when casting large-sized, especially plate-shaped heat-resistant steel billets with a width-to-thickness ratio greater than 3, sand sticking to the casting surface, honeycomb sand holes on the billet surface, and sand blasting.

Description

Technical field

[0001] The invention belongs to the technical field of metallurgical casting, and in particular relates to an ultra-long plate-shaped heat-resistant steel ingot demoulding coating and a preparation method thereof. [Background Technology]

[0002] Heat-resistant steel, due to its excellent high-temperature resistance, is widely used in industries such as science and technology, energy, transportation, and chemicals. It is an essential metal material in the petrochemical, metallurgical, and machinery industries. Due to the unique environments in which heat-resistant steel is used, strict requirements are placed on its solidification structure and material uniformity. Furthermore, due to its composition, such materials or products are typically produced by die casting, or by producing ingots through die casting, followed by electroslag remelting to enhance the material's performance to meet specific application requirements. During the die casting process, the demolding process significantly impacts casting quality, as it can easily cause the casting to become stuck, making demolding difficult. The appearance and dimensions of the ingot significantly influence this issue. Production tests have shown that larger ingot width-to-thickness ratios and lengths increase the likelihood of sticking, primarily because larger ingot widths and lengths increase the likelihood of deformation during cooling, leading to sticking. Traditional mold release coatings provide good mold release for standard-sized steel ingots (cylindrical and octagonal). However, for heat-resistant steel ingots (lengths ≥ 6m, widths 800-1200mm, and thicknesses ≤ 250mm), the increased surface area of ​​the ingot increases the internal surface area of ​​the sand mold during the molten steel casting process. This increases the adhesion and strength requirements of the coating on the sand mold's interior, otherwise the frequency of sandblasting increases. Furthermore, since the casting temperature of heat-resistant steel is 20-50°C higher than that of ordinary steel, the coating must be highly heat-resistant. Otherwise, the coating will adhere to the ingot surface, affecting not only the surface quality but also making demolding difficult. For the same ingot quality, a larger width-to-thickness ratio and length increase the internal surface area of ​​the sand mold, increasing the requirements for high-temperature adhesion, strength, and heat resistance of the coating on the interior surface. Otherwise, the coating indicators cannot meet the requirements, and it will be easy to encounter difficulties in demoulding the steel ingots with large surface areas when producing them. The frequency of sand sticking and honeycomb sand holes on the casting surface will increase, and sand flushing may even occur locally, which will seriously affect the demoulding and normal use of the ingots.

[0003] In order to solve the above problems, a release coating suitable for ultra-long slab-shaped heat-resistant steel ingots and a preparation method thereof were developed. [Summary of the invention]

[0004] The purpose of the present invention is to provide a demoulding coating for ultra-long plate-shaped heat-resistant steel ingots and a preparation method thereof, so as to solve the production problems such as demoulding difficulty, sand adhesion on the casting surface, honeycomb sand holes on the ingot surface, and sand blasting when casting large-sized plate-shaped heat-resistant steel ingots, especially those with a width-to-thickness ratio greater than 3, caused by existing coatings.

[0005] To solve the above problems, the present invention provides an ultra-long plate-shaped heat-resistant steel ingot release coating, which is composed of a refractory aggregate, a carrier, a suspending agent, a binder, and an active agent. The specific components are proportioned in parts by mass as follows:

[0006] 50-120 parts of refractory aggregate, 80-210 parts of carrier, 3-6 parts of suspending agent, 5-15 parts of binder, and 0.5-3 parts of activator.

[0007] Furthermore, the refractory aggregate is selected from zircon sand and high-alumina bauxite, and the ratio of the two by mass is: (5-10): (2-5).

[0008] Furthermore, the carrier is selected from a mixture of ethanol and dichloromethane, and the ratio of the two by mass is: (5-8): (1-3).

[0009] Furthermore, the suspending agent is prepared by mixing magnesia clay, lithium bentonite and xylene solution, wherein the ratio of magnesia clay and lithium bentonite by mass is: (3-8): (2-5), and the mixture of the two is then mixed with the xylene solution by mass ratio of (2-4): (1-2) to form a paste.

[0010] Furthermore, the binder is a mixture of ethyl cellulose and sucrose, and the mass ratio of the two is: (4-9): (0.5-2).

[0011] Furthermore, the active agent is one of sodium alkyl sulfonate, sodium lauryl sulfate, and coconut glucoside.

[0012] Furthermore, the specifications of the ultra-long plate-shaped heat-resistant steel ingot are: length ≥ 6m, and width-to-thickness ratio greater than 3.

[0013] Furthermore, the length of the super-long plate-shaped heat-resistant steel ingot is ≤15m, the width is 800-1200mm, the thickness is ≥250mm and the thickness is ≥150mm.

[0014] The present invention provides a method for preparing a release coating for an ultra-long plate-shaped heat-resistant steel ingot, comprising the following steps:

[0015] 1) Prepare the materials: Prepare the materials according to the following mass ratio:

[0016] 50-120 parts of refractory aggregate, 80-210 parts of carrier, 3-6 parts of suspending agent, 5-15 parts of binder, 0.5-3 parts of active agent, including:

[0017] The refractory aggregate is divided into two parts according to the mass ratio of (1-4): (6-15), and the two parts are ground separately. The particle size of the powder of the smaller part is controlled to be 200±10 mesh, and the particle size of the powder of the larger part is controlled to be 400±10 mesh. Then, the two parts of aggregates with different particle sizes are mixed evenly for use;

[0018] Carrier preparation: prepare ethanol and dichloromethane in a ratio of (5-8): (1-3), first inject 1 / 2-2 / 3 of the ethanol solution into the container, then inject all the dichloromethane into the container, stirring it continuously during the injection process, and finally inject all the remaining ethanol solution into the container, stir it evenly, and then seal it for later use;

[0019] The suspension agent is prepared, and the mixture of magnesia clay and lithium bentonite is ground, and the particle size of the powder is controlled at 500±10 mesh. After grinding, the mixture is mixed with xylene solution in a ratio of (2-4) parts by mass to (1-2) parts by mass to form a paste for use;

[0020] The binder is prepared, and the mixture of ethyl cellulose and sucrose is ground. The particle size of the powder after grinding is controlled to be 400±10 mesh and then used;

[0021] 2) Mixing: After mixing the refractory aggregate and binder evenly, add them into the carrier. During this period, add the prepared paste suspension and active agent into the carrier in batches and stir continuously. The stirring time is more than 3 hours.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) Due to the improved adhesion and strength of the coating at high temperatures, it can be used to produce large-sized heat-resistant steel ingots, especially ultra-long plate-shaped heat-resistant steel ingots with a width-to-thickness ratio greater than 3. During the demolding process, the ingot surface is smooth, non-sticky and free of sand holes, thereby improving the surface quality of the ingot. The surface qualification rate can reach more than 98.5%, an increase of 7.1 percentage points from the original 91.4%;

[0024] 2) By optimizing the coating formula, its heat resistance is enhanced, and sand can be prevented from sticking to the surface of the ingot during use. This can reduce the difficulty of cleaning the surface of the steel ingot used as a consumable electrode for electroslag remelting, and can improve the cleaning efficiency by 30%. [Specific implementation method]

[0025] The present invention provides a super-long plate-shaped heat-resistant steel ingot release coating and a preparation method thereof, and the specific scheme is as follows:

[0026] A) A heat-resistant steel ingot release coating comprises a refractory aggregate, a carrier, a suspending agent, a binder, and an active agent, wherein the specific components are proportioned as follows by weight:

[0027] 1) The refractory aggregate is zircon sand and high-alumina bauxite, and the mass ratio of the two is: (5-10): (2-5);

[0028] 2) The carrier is a mixture of ethanol and dichloromethane, and the weight ratio of the two is: (5-8): (1-3);

[0029] 3) The suspending agent is prepared by mixing attapulgite, lithium bentonite and xylene solution. The ratio of attapulgite and lithium bentonite by weight is: (3-8): (2-5), and the mixture of the two is then mixed with xylene solution by weight in a ratio of (2-4): (1-2) to form a paste;

[0030] 4) The binder is a mixture of ethyl cellulose and sucrose, and the ratio of the two by mass is: (4-9): (0.5-2);

[0031] 5) The active agent is one of sodium alkyl sulfonate, sodium lauryl sulfate, and coconut glucoside.

[0032] B) The specific composition of each functional component in the coating is as follows in proportion by weight:

[0033] The proportion of refractory aggregate, carrier, suspending agent, binder and active agent in parts by mass is (50-120): (80-210): (3-6): (5-15): (0.5-3).

[0034] C) Preparation process

[0035] 1) In order to improve the close packing of the refractory aggregate in the coating and the bonding strength between the aggregate particles to prevent cracking, the refractory aggregate in A) is divided into two parts according to the ratio of (1 to 4): (6 to 15) by mass, and the two parts are ground separately. The mesh size of the powder particles of the smaller part is controlled to be 200±10 mesh, and the mesh size of the powder particles of the larger part is controlled to be 400±10 mesh. Then, the two parts of aggregates of different particle sizes are evenly mixed and set aside;

[0036] 2) Carrier preparation: prepare ethanol and dichloromethane in a ratio of (5-8):(1-3) as in A). To allow the dichloromethane to fully dissolve in the ethanol, first inject the ethanol solution with a lower liquid density into the container. To reduce ethanol volatilization during stirring, first inject 1 / 2-2 / 3 of the total amount, then inject all the dichloromethane into the container, stirring continuously during the injection process, and finally inject all the remaining ethanol solution into the container. After stirring evenly, seal the container for later use.

[0037] 3) Grinding the mixture of attapulgite and lithium bentonite described in A) to control the particle size of the ground powder to 500±10 mesh, adding xylene according to the proportion described in A) to prepare a paste for later use;

[0038] 4) Preparation of a binder: To obtain a stable bonding effect, the mixture of ethyl cellulose and sucrose described in A) is ground, and the particle size of the ground powder is controlled to 400±10 mesh before use;

[0039] 5) After uniformly mixing the refractory aggregate in 1) and the binder in 4), add them to the carrier in 2). During this period, the suspension paste prepared in 3) and the active agent in A) should be added to the carrier in batches and stirred continuously for more than 3 hours to ensure that the functional components of the coating are fully mixed.

[0040] Zircon sand has high refractoriness and low expansion. Its expansion at high temperatures causes minimal damage to the sand mold surface, effectively preventing adhesion between the steel ingot and the sand mold surface. However, its relatively high price is a drawback. When used in combination with relatively inexpensive high-alumina bauxite, it can also help prevent surface defects such as sand adhesion and honeycomb-like pinholes in castings. Generally speaking, finer aggregates improve the coating's suspension stability and sintering properties. However, finer aggregates require more binder, making the coating more susceptible to cracking. To achieve a dense arrangement of aggregate particles in the coating layer, it is best to have finer particles nestled between coarser ones. To achieve this, a mix of coarse and fine refractory aggregates is used. Alcohol-based coatings are used in the carrier design. The ethanol in alcohol-based coatings is inexpensive, nearly non-toxic, and can be removed through combustion. During this process, the dichloromethane evaporates and is removed without affecting the sand mold or casting surface. When lithium bentonite is used alone in alcohol-based coatings, it is prone to sedimentation, agglomeration, and viscosity changes, and its stability is poor. However, when used in combination with magnesia-silica, sedimentation, agglomeration, and viscosity changes can be avoided, and its stability can be greatly improved.

[0041] Example 1

[0042] A method for preparing a release coating for an ultra-long plate-shaped heat-resistant steel ingot with a length of 6m, a width of 0.85m and a thickness of 0.21m, the specific scheme is as follows:

[0043] A) An ultra-long plate-shaped heat-resistant steel ingot release coating comprises a refractory aggregate, a carrier, a suspending agent, a binder, and an active agent. The specific composition ratio of each functional component is as follows:

[0044] 1) Zircon sand and high-alumina bauxite are used as refractory aggregates, and the ratio of the two by mass is 2:1 (i.e. 8:4 or 10:5);

[0045] 2) The carrier is a mixture of ethanol and dichloromethane, with the ratio of the two being 4:1 (i.e. 8:2) by mass;

[0046] 3) The suspending agent is a mixture of attapulgite and lithium bentonite, with the ratio of the two being 8:5 by mass;

[0047] 4) The binder is a mixture of ethyl cellulose and sucrose, and the ratio of the two by mass is 6:1;

[0048] 5) The active agent is sodium alkyl sulfonate.

[0049] B) The functional components in the coating are as follows in parts by mass:

[0050] 60 parts of refractory aggregate, 120 parts of carrier, 3.5 parts of suspending agent, 7 parts of binder, and 1 part of activator.

[0051] C) Preparation process

[0052] 1) The refractory aggregate in A) is divided into two parts in a mass ratio of 1.5:7, and the two parts are ground separately, wherein the particle size of the powder of the smaller part is controlled to be 200±10 mesh, and the particle size of the powder of the larger part is controlled to be 400±10 mesh. The two parts of aggregates of different particle sizes are then mixed uniformly for later use;

[0053] 2) Carrier preparation: ethanol and dichloromethane are prepared in the ratio described in A), 50% of the ethanol solution is first injected into a container, and then the dichloromethane solution is completely injected into the container, stirring continuously during the injection process. Finally, the remaining ethanol solution is completely injected into the container, stirred evenly, and sealed for later use;

[0054] 3) Grinding the mixture of attapulgite and lithium bentonite described in A) to control the particle size of the powder after grinding to 500±10 mesh, and adding xylene to the mixture after grinding to prepare a paste for later use;

[0055] 4) Grinding the mixture of ethyl cellulose and sucrose described in A) to control the particle size of the powder to 400±10 mesh and set aside;

[0056] 5) The refractory aggregate in 1) and the binder in 4) are uniformly mixed and then added to the carrier in 2). During this time, the suspension paste prepared in 3) and the active agent sodium alkyl sulfonate in A) are added to the carrier in batches and stirred continuously for 5 hours.

[0057] Example 2

[0058] A method for preparing a release coating for an ultra-long plate-shaped heat-resistant steel ingot with a length of 7m, a width of 1.0m and a thickness of 0.23m, the specific scheme is as follows:

[0059] A) An ultra-long plate-shaped heat-resistant steel ingot release coating comprises a refractory aggregate, a carrier, a suspending agent, a binder, and an active agent. The specific composition ratio of each functional component is as follows:

[0060] 1) Refractory aggregates are zircon sand and high alumina, and the ratio of the two by mass is 9:4;

[0061] 2) The carrier is a mixture of ethanol and dichloromethane, and the ratio of the two by mass is 3:1 (i.e. 6:2);

[0062] 3) The suspending agent is a mixture of attapulgite and lithium bentonite, with the ratio of the two by mass being 7:3;

[0063] 4) The binder is a mixture of ethyl cellulose and sucrose, and the ratio of the two by mass is 5:1;

[0064] 5) The active agent is sodium lauryl sulfate.

[0065] B) The functional components in the coating are as follows in parts by mass:

[0066] 80 parts of refractory aggregate, 175 parts of carrier, 4.5 parts of suspending agent, 10 parts of binder, and 1.6 parts of activator.

[0067] C) Preparation process

[0068] 1) The refractory aggregate in A) is divided into two parts in a mass ratio of 2:13, and the two parts are ground separately, wherein the particle size of the powder of the smaller part is controlled to be 200±10 mesh, and the particle size of the powder of the larger part is controlled to be 400±10 mesh. The two parts of aggregates of different particle sizes are then mixed uniformly for later use;

[0069] 2) Carrier preparation: ethanol and dichloromethane are prepared in the ratio described in A), 50% of the ethanol solution is first injected into a container, and then the dichloromethane solution is completely injected into the container, stirring continuously during the injection process. Finally, the remaining ethanol solution is completely injected into the container, stirred evenly, and sealed for later use;

[0070] 3) Grinding the mixture of attapulgite and lithium bentonite described in A) to control the particle size of the ground powder to 500±10 mesh, adding xylene to form a paste for later use;

[0071] 4) Grinding the mixture of ethyl cellulose and sucrose described in A) to control the particle size of the powder to 400±10 mesh and set aside;

[0072] 5) The refractory aggregate in 1) and the binder in 4) are uniformly mixed and then added to the carrier in 2). During this time, the suspension paste prepared in 3) and the active agent sodium lauryl sulfate in A) are added to the carrier in batches and continuously stirred for 8 hours.

[0073] Example 3

[0074] A method for preparing a release coating for an ultra-long plate-shaped heat-resistant steel ingot with a length of 9m, a width of 1.1m and a thickness of 0.25m, the specific scheme is as follows:

[0075] A) An ultra-long plate-shaped heat-resistant steel ingot release coating comprises a refractory aggregate, a carrier, a suspending agent, a binder, and an active agent. The specific composition ratio of each functional component is as follows:

[0076] 1) Refractory aggregates are zircon sand and high alumina, and the ratio of the two by mass is 8:3;

[0077] 2) The carrier is a mixture of ethanol and dichloromethane, and the ratio of the two by mass is 5:1;

[0078] 3) The suspending agent is a mixture of attapulgite and lithium bentonite, with the ratio of the two being 4:3 by mass;

[0079] 4) The binder is a mixture of ethyl cellulose and sucrose, and the ratio of the two by mass is 5:1.5;

[0080] 5) The active agent is coco-glucoside.

[0081] B) The functional components in the coating are as follows in parts by mass:

[0082] 85 parts of refractory aggregate, 170 parts of carrier, 5.5 parts of suspending agent, 12 parts of binder, and 1.5 parts of activator.

[0083] C) Preparation process

[0084] 1) The refractory aggregate in A) is divided into two parts in a mass ratio of 3:13, and the two parts are ground separately, wherein the particle size of the powder of the smaller part is controlled to be 200±10 mesh, and the particle size of the powder of the larger part is controlled to be 400±10 mesh. The two parts of aggregates of different particle sizes are then mixed uniformly for later use;

[0085] 2) Carrier preparation: ethanol and dichloromethane are prepared in the ratio described in A), 50% of the ethanol solution is first injected into a container, and then the dichloromethane solution is completely injected into the container, stirring continuously during the injection process. Finally, the remaining ethanol solution is completely injected into the container, stirred evenly, and sealed for later use;

[0086] 3) Grinding the mixture of attapulgite and lithium bentonite described in A) to control the particle size of the ground powder to 500±10 mesh, adding xylene to form a paste for later use;

[0087] 4) Grinding the mixture of ethyl cellulose and sucrose described in A) to control the particle size of the powder to 400±10 mesh and set aside;

[0088] 5) The refractory aggregate in 1) and the binder in 4) are uniformly mixed and then added to the carrier in 2). During this time, the suspending agent paste prepared in 3) and the active agent cocoyl glucoside in A) are added to the carrier in batches and stirred continuously for 7 hours.

[0089] The comparison of usage effects is shown below:

[0090] Paint type Sand sticking rate per 100 ingots, % Surface characteristics Sand cleaning time, min / block Original paint 10.2 Rough 45 Example 1 2.5 Smoother 12 Example 2 1.8 smooth 8 Example 3 1.7 smooth 8

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A mold release coating for ultra-long plate-shaped heat-resistant steel ingots, characterized in that: It is composed of refractory aggregate, carrier, suspending agent, binder and active agent. The specific components are proportioned by mass as follows: 50-120 parts of refractory aggregate, 80-210 parts of carrier, 3-6 parts of suspending agent, 5-15 parts of binder, 0.5-3 parts of active agent; The refractory aggregate is made of zircon sand and high-alumina bauxite, and the ratio of the two by mass is: (5-10): (2-5); The carrier is a mixture of ethanol and dichloromethane, and the ratio of the two parts by mass is: (5-8): (1-3); The suspending agent is prepared by mixing magnesia clay, lithium bentonite and xylene solution, wherein the ratio of magnesia clay and lithium bentonite by mass is (3-8): (2-5), and the mixture of the two is then mixed with the xylene solution by mass ratio of (2-4): (1-2) to form a paste; The binder is a mixture of ethyl cellulose and sucrose, and the mass ratio of the two is: (4-9): (0.5-2).

2. The ultra-long plate-shaped heat-resistant steel ingot release coating according to claim 1, characterized in that: The active agent is one of sodium alkyl sulfonate, sodium lauryl sulfate, and coconut glucoside.

3. The mold release coating for ultra-long plate-shaped heat-resistant steel ingot according to claim 1, characterized in that: The specifications of super-long plate-shaped heat-resistant steel ingots are: length ≥6m, width-to-thickness ratio greater than 3.

4. The mold release coating for ultra-long plate-shaped heat-resistant steel ingot according to claim 3, characterized in that: The length of the super-long plate-shaped heat-resistant steel ingot is ≤15m, the width is 800~1200mm, 250mm≥, and the thickness is ≥150mm.

5. A method for preparing a release coating for ultra-long plate-shaped heat-resistant steel ingots according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) Prepare the materials: Prepare the materials according to the following mass ratio: 50-120 parts of refractory aggregate, 80-210 parts of carrier, 3-6 parts of suspending agent, 5-15 parts of binder, 0.5-3 parts of active agent, including: Divide the refractory aggregate into two parts according to the mass ratio of (1-4): (6-15), grind the two parts separately, control the particle size of the powder of the smaller part to 200±10 mesh, and control the particle size of the powder of the larger part to 400±10 mesh, then mix the two parts of aggregates with different particle sizes evenly for later use; Carrier preparation: prepare ethanol and dichloromethane in a ratio of (5-8): (1-3), first inject 1 / 2-2 / 3 of the ethanol solution into the container, then inject all the dichloromethane into the container, stirring it continuously during the injection process, and finally inject all the remaining ethanol solution into the container, stir it evenly, and then seal it for later use; The suspension agent is prepared by grinding the mixture of magnesia silicate and lithium bentonite, and the particle size of the powder is controlled at 500±10 mesh. After grinding, the mixture is mixed with xylene solution in a ratio of (2-4) by mass: (1-2) to form a paste for use; The binder is prepared, and the mixture of ethyl cellulose and sucrose is ground. The particle size of the powder after grinding is controlled to be 400±10 mesh and then used; 2) Mixing: After mixing the refractory aggregate and binder evenly, add them into the carrier. During this period, add the prepared paste suspension and active agent into the carrier in batches and stir continuously. The stirring time should be more than 3 hours.