Protective and heat-insulating coating that can be applied to red-hot metal and its application

Abstract

The present invention provides a protective and heat-insulating coating that can be applied to red-hot metals and its application. The protective and heat-insulating coating comprises 5-15 parts of glass powder, 5-20 parts of Al2O3, 2-10 parts of SiO2, 2-5 parts of ZrB2, 1-10 parts of SiC, 5-15 parts of Cr2O3, 1-5 parts of Cr3C2, 10-40 parts of binder and 10-20 parts of water; the glass powder is composed of 5-10 parts of SiO2, 1-4 parts of Al2O3, 5-15 parts of B2O3, 0-5 parts of Na2O, 25-35 parts of BaO, 20-30 parts of Bi2O3, 10-20 parts of PbO and 5-10 parts of Sb2O3. The protective and heat-insulating coating of the present invention can be directly applied to the metal surface with a surface temperature not higher than 1000 °C, achieving good heat insulation and heat preservation effects, improving production efficiency and the quality of forgings, and reducing forging costs.

Description

Technical Field

[0001] The present invention relates to the technical field of metal protective coatings, and more specifically, to a protective and heat-insulating coating that can be applied to red-hot metals and its applications. Background Art

[0002] With the development of large forging manufacturing technology and the transformation and upgrading of product structures, the manufacturing of high-end products with special materials, complex structures, and higher quality index requirements will be a difficult problem that the large forging industry must face for sustainable development. Due to the generally long heating time and high heating temperature of large forgings, oxidation, alloy element depletion, hydrogen absorption, and nitrogen absorption will inevitably occur at high temperatures, resulting in much more serious phenomena such as reduced plasticity and increased surface high-temperature corrosion products compared to small forgings, seriously affecting the quality of forgings after forging, and even making the forging process impossible to proceed.

[0003] In order to address the problems of large deformation, multiple forging heats, and easy oxidation of forgings at high temperatures for a long time during the forging of large forgings, the existing technology solves the oxidation problem by increasing the machining allowance, increasing the size of the metal forging blank to increase the machining allowance, and removing the oxide layer, decarburized layer, depleted layer, etc. on the surface of the metal forging by mechanical machining after heat treatment. However, this increases the raw material cost and the production cost of forgings, and causes significant waste of raw materials. In order to address the problem of multiple forging heats and the need for long-term high-temperature heat preservation during the forging of large forgings, the existing technology uses ceramic fiber blankets to soft-wrap the surface of the forgings. However, the heat preservation method using ceramic fiber blanket soft-wrap has a negative impact on environmental protection and on-site labor protection in the workshop.

[0004] In addition, during the multi-heat forging process of large forgings, in order to improve production efficiency and reduce production costs, after the forging of the previous heat is completed, the forgings are directly heated in the furnace to the forging temperature of the next heat, rather than waiting for the forgings to cool to room temperature before heating in the furnace. Traditional glass protective lubricants are applied to the surface of metal forging blanks before heating. However, during the multi-heat forging process of large forgings, since the forgings cannot wait for an extremely long cooling time after each heat forging, it is impossible to apply traditional glass protective lubricants for protection and heat preservation. Summary of the Invention

[0005] The main objective of the present invention is to provide a protective and heat-insulating coating that can be applied to red-hot metals and its applications, so as to solve the problem in the prior art that it is difficult to protect and insulate red-hot metals.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided a protective and heat-insulating coating that can be applied to red-hot metal, where the red-hot metal is a metal with a surface temperature of 600 to 1000 °C; by weight, the protective and heat-insulating coating includes 5 to 15 parts of glass powder, 5 to 20 parts of Al2O3, 2 to 10 parts of SiO2, 2 to 5 parts of ZrB2, 1 to 10 parts of SiC, 5 to 15 parts of Cr2O3, 1 to 5 parts of Cr3C2, 10 to 40 parts of binder, and 10 to 20 parts of water; among them, by weight, the glass powder is composed of 5 to 10 parts of SiO2, 1 to 4 parts of Al2O3, 5 to 15 parts of B2O3, 0 to 5 parts of Na2O, 25 to 35 parts of BaO, 20 to 30 parts of Bi2O3, 10 to 20 parts of PbO, and 5 to 10 parts of Sb2O3.

[0007] Further, by weight, the protective and heat-insulating coating includes 7 to 15 parts of glass powder, 10 to 20 parts of Al2O3, 5 to 10 parts of SiO2, 2 to 4 parts of ZrB2, 1 to 6 parts of SiC, 8 to 13 parts of Cr2O3, 1 to 3 parts of Cr3C2, 20 to 30 parts of binder, and 15 to 20 parts of water.

[0008] Further, by weight, the glass powder is composed of 6 to 8 parts of SiO2, 1 to 3 parts of Al2O3, 8 to 13 parts of B2O3, 1 to 3 parts of Na2O, 25 to 30 parts of BaO, 20 to 25 parts of Bi2O3, 10 to 15 parts of PbO, and 5 to 8 parts of Sb2O3.

[0009] Further, by weight, the protective and heat-insulating coating further includes 1 to 5 parts of kaolin and 5 to 10 parts of sericite.

[0010] Further, the binder is potassium water glass and / or silica sol; preferably, by weight, the binder includes 10 to 20 parts of potassium water glass and 10 to 20 parts of silica sol; more preferably, the modulus of the potassium water glass is 2 to 3.

[0011] Further, the material of the red-hot metal includes one or more of steel, titanium, titanium alloy, and superalloy; preferably, when the material of the red-hot metal is steel, by weight, the protective and heat-insulating coating includes 7-9 parts of glass powder, 17-20 parts of Al2O3, 5-7 parts of SiO2, 3-4 parts of ZrB2, 4-6 parts of SiC, 11-13 parts of Cr2O3, 2-3 parts of Cr3C2, 25-30 parts of binder, and 15-17 parts of water; preferably, when the material of the red-hot metal is titanium and / or titanium alloy, by weight, the protective and heat-insulating coating includes 13-15 parts of glass powder, 10-12 parts of Al2O3, 8-10 parts of SiO2, 2-3 parts of ZrB2, 1-2 parts of SiC, 8-10 parts of Cr2O3, 1-2 parts of Cr3C2, 20-25 parts of binder, and 18-20 parts of water; preferably, when the material of the red-hot metal is superalloy, by weight, the protective and heat-insulating coating includes 10-13 parts of glass powder, 13-16 parts of Al2O3, 6-8 parts of SiO2, 3-4 parts of ZrB2, 4-6 parts of SiC, 10-12 parts of Cr2O3, 2-3 parts of Cr3C2, 25-30 parts of binder, and 16-18 parts of water; more preferably, the steel includes 0Cr18Ni9 and / or 1Cr18Ni9Ti, the titanium alloy includes TC4 and / or TC11, and the superalloy includes GH141 and / or GH718.

[0012] According to another aspect of the present invention, there is provided a method for protecting and heat-insulating the forging process of red-hot metal. The components of the above protective and heat-insulating coating of the present invention are respectively weighed and mixed, and then subjected to ball milling and aging in sequence, and then coated on the surface of the red-hot metal. After the coating formed by the protective and heat-insulating coating is dried, it is forged together with the red-hot metal.

[0013] Further, the ball-to-material ratio of the ball milling is (2-4):1, the rotation speed is 50-100 revolutions / min, and the time is 10-14 h; and / or the aging time is 0.5-2 days.

[0014] Further, the coating is spraying or brushing; preferably, the coating thickness of the protective and heat-insulating coating is 0.2-1 mm, and the coating dosage is 0.25-1 kg / m 2 .

[0015] Furthermore, the material of the red-hot metal includes one or more of steel, titanium, titanium alloy, and superalloy; preferably, when the material of the red-hot metal is steel, the heating temperature for forging is 600-1300 °C, and the holding time is 0-60 h, preferably 25-40 h; preferably, when the material of the red-hot metal is titanium and / or titanium alloy, the heating temperature for forging is 600-1200 °C, and the holding time is 0-60 h, preferably 20-30 h; preferably, when the material of the red-hot metal is superalloy, the heating temperature for forging is 600-1200 °C, and the holding time is 0-60 h, preferably 20-30 h.

[0016] The protective and heat-insulating coating of the present invention can be directly coated on the metal surface with a surface temperature not higher than 1000 °C. The low-melting-point component therein enables the protective and heat-insulating coating to quickly melt and firmly adhere to the surface of the red-hot metal forging when it comes into contact with the surface, and quickly form a continuous, dense, and uniform glass film; after being heated in the furnace with the forging, the high-melting-point component in the protective and heat-insulating coating will gradually melt, enabling the glass film formed on the surface of the forging to continuously and stably exist, thereby isolating the influence of harmful gases on the forging throughout the entire heat process and achieving a good protective effect. At the same time, the formed glass film also has good heat insulation and heat preservation effects, which can reduce the temperature drop of the workpiece, extend the forging time, reduce the number of forging heats during the hot working processes such as forging after the metal forging is heated, thereby improving production efficiency and the quality of the forging, and reducing forging costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 Shows a photo of the coated state after brushing according to Embodiment 1 of the present invention;

[0019] Figure 2 Shows a photo of the coated state at 1020 °C according to Embodiment 1 of the present invention;

[0020] Figure 3 Shows a photo of the coated state after spraying according to Embodiment 4 of the present invention; and

[0021] Figure 4 Shows a photo of the coated state at 960 °C according to Embodiment 4 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0023] Glossary:

[0024] Red-hot metal: High-temperature metal with a surface temperature not higher than 1000 °C.

[0025] As described in the background art of the present invention, there is a problem in the prior art that it is difficult to protect and insulate red-hot metal. To solve the above problem, in a typical embodiment of the present invention, a protective and insulating coating that can be applied to red-hot metal is provided. The red-hot metal is a metal with a surface temperature of 600-1000 °C. By weight, the protective and insulating coating includes 5-15 parts of glass powder, 5-20 parts of Al2O3, 2-10 parts of SiO2, 2-5 parts of ZrB2, 1-10 parts of SiC, 5-15 parts of Cr2O3, 1-5 parts of Cr3C2, 10-40 parts of binder, and 10-20 parts of water. Among them, by weight, the glass powder is composed of 5-10 parts of SiO2, 1-4 parts of Al2O3, 5-15 parts of B2O3, 0-5 parts of Na2O, 25-35 parts of BaO, 20-30 parts of Bi2O3, 10-20 parts of PbO, and 5-10 parts of Sb2O3.

[0026] The inventors unexpectedly found during the research process that the protective and insulating coating that can be applied to the surface of red-hot metal forgings is essentially different from the traditional glass protective coating in terms of the coating object and method. The traditional glass protective coating is applied to the surface of the metal forging blank before initial heating, while the protective and insulating coating that can be applied to the surface of red-hot metal forgings needs to be directly applied to the surface of red-hot metal forgings at 600-1000 °C. Therefore, it is necessary to use amorphous glass as the main solid base material and add a certain amount of special composite low-melting glass, which acts synergistically with other additives, adhesives, and water to ensure that the protective and insulating coating can quickly melt and firmly adhere to the surface of the red-hot metal forgings at 600-1000 °C, and quickly form a continuous, dense, and uniform glass film to isolate the thermal corrosion of harmful gases on the red-hot metal forgings.

[0027] After the forgings are heated in the furnace to a temperature above 1000 °C, the high-melting-point components in the protective and insulating coating will gradually melt, enabling the glass film formed on the surface of the forgings to exist continuously and stably. Thus, it can isolate the influence of harmful gases such as O2, H2, N2, and SO2 on the forgings throughout the entire thermal process, achieving a good protective effect. Furthermore, it can improve the material utilization rate, inhibit grain boundary corrosion and alloy element depletion, and ensure that the mechanical properties such as the strength, stiffness, and hardness of the metal are not affected by the high-temperature environment.

[0028] Meanwhile, the formed glass film also has good heat insulation and heat preservation effects. When the metal forging is taken out of the furnace for transfer or during forging, the protective heat preservation coating can reduce the temperature drop of the workpiece and play a heat preservation role, thereby extending the forging time. Especially for forgings with a long forging time and a narrow forging temperature range, the good heat preservation effect can reduce the number of forging heats, thus improving production efficiency. At the same time, it also avoids excessive heat transfer from the blank to the die, extending the service life of the die.

[0029] Specifically, in the above-mentioned protective heat preservation coating, the glass powder can rapidly melt to form a dense and uniform film after the metal blank is heated in the furnace, playing a good protective role in the initial stage of heating; Al2O3 can form a dense ceramic film layer at high temperature and has good high-temperature stability; SiO2 can form a dense glass film layer at high temperature and improve the high-temperature stability of the glass powder; ZrB2 has excellent thermodynamic stability and oxidation resistance, but the defect is that it is not wetted with the metal substrate and it is difficult to adhere tightly to the surface of the metal substrate. Therefore, the present invention also adds Cr3C2 to significantly improve this defect; SiC can also form glassy SiO2 at high temperature and has a good protective effect; Cr2O3 has good wettability with the metal substrate and can improve the bonding strength between the coating and the metal substrate at high temperature. The protective heat preservation coating with the above specific components of the present invention can effectively inhibit problems such as oxidation, decarburization, hydrogen absorption or alloy element depletion during the high-temperature treatment of red-hot metals, and has a wider application range.

[0030] The protective heat preservation coating that can be coated on red-hot metals of the present invention is mainly applied to the multi-heat forging process of large forgings. The coating of the protective heat preservation coating is completed after the previous heat forging is completed and before the next heat forging is heated in the furnace. At this time, the surface temperature of the large forging is usually about 600 - 1000 °C. During the die forging process of the large forging, the metal surface protective heat preservation coating forms a uniform, dense and closed molten glass film at high temperature, playing a protective role during the heating process of the forging in the furnace and a heat preservation role during the forging process. It can ensure that harmful gases are isolated from the thermal corrosion of the forging throughout the heat process; and improve the plasticity and surface quality of the workpiece, reduce the machining allowance, save equipment energy during the hot forming of the forging, reduce heat loss during the transfer of the forging, extend the forging time, reduce the number of forging heats, prevent the tool and die from overheating, and extend the die life.

[0031] For the purpose of further improving the protective effect and heat preservation effect, in a preferred embodiment, by weight, the protective heat preservation coating includes 7 - 15 parts of glass powder, 10 - 20 parts of Al2O3, 5 - 10 parts of SiO2, 2 - 4 parts of ZrB2, 1 - 6 parts of SiC, 8 - 13 parts of Cr2O3, 1 - 3 parts of Cr3C2, 20 - 30 parts of binder and 15 - 20 parts of water.

[0032] In a preferred embodiment, by weight parts, the glass powder is composed of 6-8 parts of SiO2, 1-3 parts of Al2O3, 8-13 parts of B2O3, 1-3 parts of Na2O, 25-30 parts of BaO, 20-25 parts of Bi2O3, 10-15 parts of PbO, and 5-8 parts of Sb2O3. The glass film formed by melting the glass powder of the above components is more continuous, dense, and uniform, and can better isolate the hot corrosion of harmful gases on the red-hot metal forging, and has a better protective effect during the process of heating the forging in the furnace.

[0033] In order to further improve the high-temperature stability of the coating, in a preferred embodiment, by weight parts, the protective and heat-insulating coating further includes 1-5 parts of kaolin and 5-10 parts of sericite. At the same time, the above components are easily dispersed in water, which can further improve the coatability of the coating. Preferably, the particle size of each solid component in the above coating is controlled within 200-400 mesh.

[0034] In a preferred embodiment, the binder is potassium silicate and / or silica sol; preferably, by weight parts, the binder includes 10-20 parts of potassium silicate and 10-20 parts of silica sol; more preferably, the modulus of potassium silicate is 2-3, where the modulus refers to the molar ratio of SiO2 and K2O. Under the above conditions, the dissolution and bonding effects of the coating are better, and it is more convenient for the subsequent coating of the coating.

[0035] For more convenient practical application, in a preferred embodiment, the material of the red-hot metal includes one or more of steel, titanium, titanium alloy, and superalloy; preferably, when the material of the red-hot metal is steel, by weight, the protective and heat-insulating coating includes 7-9 parts of glass powder, 17-20 parts of Al2O3, 5-7 parts of SiO2, 3-4 parts of ZrB2, 4-6 parts of SiC, 11-13 parts of Cr2O3, 2-3 parts of Cr3C2, 25-30 parts of binder, and 15-17 parts of water, which can better prevent the oxidation and decarburization of steel; preferably, when the material of the red-hot metal is titanium and / or titanium alloy, by weight, the protective and heat-insulating coating includes 13-15 parts of glass powder, 10-12 parts of Al2O3, 8-10 parts of SiO2, 2-3 parts of ZrB2, 1-2 parts of SiC, 8-10 parts of Cr2O3, 1-2 parts of Cr3C2, 20-25 parts of binder, and 18-20 parts of water, which can better prevent the oxidation and hydrogen absorption of the titanium alloy; preferably, when the material of the red-hot metal is superalloy, by weight, the protective and heat-insulating coating includes 10-13 parts of glass powder, 13-16 parts of Al2O3, 6-8 parts of SiO2, 3-4 parts of ZrB2, 4-6 parts of SiC, 10-12 parts of Cr2O3, 2-3 parts of Cr3C2, 25-30 parts of binder, and 16-18 parts of water, which can better prevent the oxidation and element depletion of the superalloy; more preferably, the steel includes 0Cr18Ni9 and / or 1Cr18Ni9Ti, the titanium alloy includes TC4 and / or TC11, and the superalloy includes GH141 and / or GH718.

[0036] The above-mentioned corresponding protective and heat-insulating coating of the present invention can play a very good protective role during the heating process, so that more targeted protective and heat-insulating coatings can be used for different metals, and the effects of isolating harmful gases and slowing down the temperature drop are better, further improving the protective and heat-insulating effects.

[0037] In another typical embodiment of the present invention, a method for protecting and heat-insulating the forging process of red-hot metal is also provided. Each component of the above-mentioned protective and heat-insulating coating of the present invention is weighed and mixed respectively, and then ball-milled and aged in sequence, and then coated on the surface of the red-hot metal. After the coating formed by the protective and heat-insulating coating is dried, it is forged together with the red-hot metal. The protective and heat-insulating coating of the present invention has better protective and heat-insulating effects, overcoming the defects that the existing soft package forging insulation technology does not have a protective function and cannot prevent the high-temperature oxidation of forgings. Moreover, the coating preparation process used in the above method of the present invention is simple, can realize mass production, maintain good product consistency, and has a lower cost, and the usage method is simpler than the existing soft package technology.

[0038] In a preferred embodiment, the ball-to-material ratio of ball milling is (2-4):1, the rotation speed is 50-100 revolutions per minute, and the time is 10-14 hours; and / or the aging time is 0.5-2 days, which is more convenient for coating preparation.

[0039] The protective and heat-insulating coating of the present invention is directly applied to the surface of a red-hot metal forging at 600-1000°C. For a relatively large forging, in a preferred embodiment, the coating is applied by spraying or brushing, so as to further improve the spraying efficiency and quality; preferably, the coating thickness of the protective and heat-insulating coating is 0.2-1 mm, and the coating dosage is 0.25-1 kg / m 2 , so that the coating can further maintain a good protective effect in a high-temperature environment.

[0040] Specifically, in a preferred embodiment, the material of the red-hot metal includes one or more of steel, titanium, titanium alloy and superalloy; preferably, when the material of the red-hot metal is steel, the forging heating temperature is 600-1300°C, and the holding time is 0-60 hours, preferably 25-40 hours; preferably, when the material of the red-hot metal is titanium and / or titanium alloy, the forging heating temperature is 600-1200°C, and the holding time is 0-60 hours, preferably 20-30 hours; preferably, when the material of the red-hot metal is superalloy, the forging heating temperature is 600-1200°C, and the holding time is 0-60 hours, preferably 20-30 hours. Thus, it can play a good heat-insulating role during the forging process after the metal heating is completed and the forging is taken out of the furnace, further extend the forging time, reduce the number of forging heats, improve the production efficiency of the forging, and reduce the production cost of the forging. The forging prepared under the above conditions has better performance.

[0041] Typically but not limited to, the protective and heat-insulating coating comprises components in the following parts by weight or the boundary values formed by any two of these values: 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts of glass powder; 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts of Al2O3; 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts of SiO2; 2 parts, 3 parts, 4 parts, 5 parts of ZrB2; 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts of SiC; 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts of Cr2O3; 1 part, 2 parts, 3 parts, 4 parts, 5 parts of Cr3C2; 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts of binder; 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts of water.

[0042] Typically but not limited to, the glass powder comprises components in the following parts by weight or the boundary values formed by any two of these values: 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts of SiO2; 1 part, 2 parts, 3 parts, 4 parts of Al2O3; 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts of B2O3; 0 part, 1 part, 2 parts, 3 parts, 4 parts, 5 parts of Na2O; 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts of BaO; 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts of Bi2O3; 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts of PbO; 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts of Sb2O3.

[0043] Typically but not limited to, the binder comprises 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts or the boundary values formed by any two of these values of potassium water glass and 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts or the boundary values formed by any two of these values of silica sol.

[0044] Typically but not limited to, when the material of the red-hot metal is steel, the protective and heat-insulating coating includes components in the following parts by weight or the boundary values formed by any two of its values: 7 parts, 8 parts, 9 parts of glass powder, 17 parts, 18 parts, 19 parts, 20 parts of Al2O3, 5 parts, 6 parts, 7 parts of SiO2, 3 parts, 4 parts of ZrB2, 4 parts, 5 parts, 6 parts of SiC, 11 parts, 12 parts, 13 parts of Cr2O3, 2 parts, 3 parts of Cr3C2, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts of binder, 15 parts, 16 parts, 17 parts of water.

[0045] Typically but not limited to, when the material of the red-hot metal is titanium and / or titanium alloy, the protective and heat-insulating coating includes components in the following parts by weight or the boundary values formed by any two of its values: 13 parts, 14 parts, 15 parts of glass powder, 10 parts, 11 parts, 12 parts of Al2O3, 8 parts, 9 parts, 10 parts of SiO2, 2 parts, 3 parts of ZrB2, 1 part, 2 part of SiC, 8 parts, 9 parts, 10 parts of Cr2O3, 1 part, 2 parts of Cr3C2, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts of binder, 18 parts, 19 parts, 20 parts of water.

[0046] Typically but not limited to, when the material of the red-hot metal is superalloy, the protective and heat-insulating coating includes components in the following parts by weight or the boundary values formed by any two of its values: 10 parts, 11 parts, 12 parts, 13 parts of glass powder, 13 parts, 14 parts, 15 parts, 16 parts of Al2O3, 6 parts, 7 parts, 8 parts of SiO2, 3 parts, 4 parts of ZrB2, 4 parts, 5 parts, 6 parts of SiC, 10 parts, 11 parts, 12 parts of Cr2O3, 2 parts, 3 parts of Cr3C2, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts of binder, 16 parts, 17 parts, 18 parts of water.

[0047] Typically but not limited to, when the material of the red-hot metal is steel, the forging heating temperature is 600°C, 700°C, 800°C, 900°C, 1000°C, 1020°C, 1100°C, 1200°C, 1300°C or the boundary values formed by any two of its values, and the heat preservation time is 25°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C, 40 h or the boundary values formed by any two of its values.

[0048] Typically but not limited to, when the material of the red-hot metal is titanium and / or titanium alloy, the forging heating temperature is 600°C, 700°C, 800°C, 900°C, 960°C, 1000°C, 1100°C, 1200°C or the boundary values formed by any two of its values, and the heat preservation time is 20°C, 22°C, 24°C, 26°C, 28°C, 30 h or the boundary values formed by any two of its values.

[0049] Typically but not limitedly, when the material of the red-hot metal is a superalloy, the forging heating temperature is 600 °C, 700 °C, 800 °C, 900 °C, 960 °C, 1000 °C, 1100 °C, 1200 °C or the boundary values composed of any two of these values, and the heat preservation time is 20 °C, 22 °C, 24 °C, 26 °C, 28 °C, 30 h or the boundary values composed of any two of these values.

[0050] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application.

[0051] Example 1: Protective heat preservation coating for red-hot metal with the material of 0Cr18Ni9 stainless steel

[0052] The forging process is free forging in 10 heats: the heating temperature is 1020 °C, the heat preservation time is 25 h, the surface temperature of the forging after each heat of free forging is 650 ± 30 °C, and the protective heat preservation coating is immediately brushed after each heat of free forging. The coating rapidly melts on the surface of the forging blank to form a dense, continuous and uniform film layer, which plays a protective role during the process of heating the forging in the furnace and a heat preservation role during the forging process.

[0053] GRF-66 protective heat preservation coating was prepared, and its component ratio is shown in Tables 1 to 2. The particle size of each solid component was controlled at 200 - 400 mesh, and the modulus of potassium water glass was 2 - 3. After weighing the above components, they were put into a ball mill tank and ball milled with a roller ball mill. The ball-to-material ratio was 3:1, the ball milling speed was 75 revolutions per minute, and the ball milling time was 12 h. After ball milling, the coating was poured out and aged for 1 day, and then it could be brushed on the stainless steel surface during forging. The coating thickness was 1 mm, and the coating dosage was 1 kg / m 2 . Then it could be heated in the furnace together with the steel parts.

[0054] The photos of the coating state after brushing are shown in Figure 1 , and the photos of the coating state at 1020 °C are shown in Figure 2 . After verification, the oxide layer on the metal surface protected by the coating was significantly reduced, and the thickness of the oxide layer on the metal surface protected by the coating was reduced by about 80% compared with that without coating protection. At the same time, in the coated area, the surface temperature during forging was always 50 - 80 °C higher than that in the uncoated area, and the protective and heat preservation performances were good.

[0055] Examples 2 to 3

[0056] The difference from Example 1 is that the components of the protective heat preservation coating are different, as shown in Table 1 for details.

[0057] Example 4: Protective heat preservation coating for red-hot metal with the material of TC4 titanium alloy

[0058] The forging process is free forging with 7 heating cycles: the heating temperature is 960 °C, the holding time is 25 h, the surface temperature of the forgings after each free forging is 850 ± 30 °C, and the protective and heat-insulating coating is sprayed immediately after each free forging. The coating rapidly melts on the surface of the forging blank to form a dense, continuous, and uniform film layer, which plays a protective role during the heating process of the forging in the furnace and a heat-insulating role during the forging process.

[0059] The TRF-70 protective and heat-insulating coating was prepared, and its component ratios are shown in Tables 1 to 2. The particle sizes of the solid components are controlled within 200 - 400 mesh, and the modulus of potassium silicate is 2 - 3. After weighing the above components, they are put into a ball milling tank and ball milled with a roller ball mill. The ball-to-material ratio is 3:1, the ball milling speed is 75 revolutions per minute, and the ball milling time is 12 h. After ball milling, the coating is poured out and can be sprayed on the surface of the titanium alloy during forging after aging for 1 day. The coating thickness is 1 mm, and the coating dosage is 1 kg / m 2 . Then it can be heated in the furnace together with the titanium alloy.

[0060] Photos of the coating state after spraying are shown in Figure 3 , and photos of the coating state at 960 °C are shown in Figure 4 . After verification, the oxide layer on the metal surface protected by the coating is significantly reduced, and the thickness of the oxide layer on the metal surface without coating protection is reduced by about 80%. At the same time, in the coated area, its surface temperature during forging is always 50 - 80 °C higher than that in the uncoated area, and the protective and heat-insulating performance is good.

[0061] Examples 5 to 6

[0062] The difference from Example 4 is that the components of the protective and heat-insulating coating are different, as shown in Table 1 for details.

[0063] Example 7: Protective and heat-insulating coating for red-hot metal with the material of GH141 superalloy

[0064] The forging process is free forging with 7 heating cycles: the heating temperature is 960 °C, the holding time is 25 h, the surface temperature of the forgings after each free forging is 850 ± 30 °C, and the protective and heat-insulating coating is sprayed immediately after each free forging. The coating rapidly melts on the surface of the forging blank to form a dense, continuous, and uniform film layer, which plays a protective role during the heating process of the forging in the furnace and a heat-insulating role during the forging process.

[0065] A protective and heat-insulating coating was prepared. The component ratios are shown in Tables 1 to 2. The particle sizes of the solid components are controlled within 200 to 400 mesh, and the modulus of potassium silicate is 2 to 3. After weighing the above components, they are put into a ball mill tank and ball-milled with a roller ball mill. The ball-to-material ratio is 3:1, the ball-milling speed is 75 revolutions / min, and the ball-milling time is 12 h. After ball-milling, the coating is poured out and can be sprayed on the surface of the superalloy during forging after aging for 1 day. The coating thickness is 1 mm, and the coating dosage is 1 kg / m 2 . Then it can be heated in the furnace together with the superalloy.

[0066] It has been verified that the oxide layer on the metal surface with coating protection is significantly reduced. Compared with the oxide layer on the metal surface without coating protection, the thickness is reduced by about 80%. At the same time, in the coated area, the surface temperature during forging is always 50 to 80 °C higher than that in the uncoated area, and the protection and heat-insulating performance are good.

[0067] Examples 8 to 9

[0068] The difference from Example 7 is that the components of the protective and heat-insulating coating are different, as shown in Table 1 for details.

[0069] Examples 10 to 13

[0070] The difference from Example 1 is that the components of the protective and heat-insulating coating are different, as shown in Table 1 for details.

[0071] Examples 14 to 17

[0072] The difference from Example 1 is that the components of the glass powder are different, as shown in Table 2 for details.

[0073] Example 18

[0074] The difference from Example 1 is that the heating temperature for forging is 600 °C and the heat-insulating time is 40 h.

[0075] Example 19

[0076] The difference from Example 1 is that the heating temperature for forging is 1300 °C and the heat-insulating time is 30 h.

[0077] Example 20

[0078] The difference from Example 4 is that the heating temperature for forging is 600 °C and the heat-insulating time is 30 h.

[0079] Example 21

[0080] The difference from Example 4 is that the heating temperature for forging is 1200 °C and the heat-insulating time is 20 h.

[0081] Example 22

[0082] The difference from Example 7 is that the forging heating temperature is 600 °C and the heat preservation time is 30 h.

[0083] Example 23

[0084] The difference from Example 7 is that the forging heating temperature is 1200 °C and the heat preservation time is 20 h.

[0085] Comparative Example 1

[0086] The difference from Example 1 is that the protective heat-insulating coating uses the coating of Example 1 of CN 111499395 A. After verification, the coating cannot firmly adhere to the stainless-steel surface. The oxide layer on the metal surface with coating protection is partially reduced, and the thickness of the oxide layer on the metal surface with coating protection is reduced by about 30% compared with that on the metal surface without coating protection. At the same time, in the coated area, the surface temperature during forging is 20-30 °C higher than that in the uncoated area, and the protective and heat-insulating properties are average.

[0087] Comparative Example 2

[0088] The difference from Example 1 is that the protective heat-insulating coating uses the coating of Example 1 of CN 115612358 A. After verification, the coating cannot firmly adhere to the stainless-steel surface. The oxide layer on the metal surface with coating protection is partially reduced, and the thickness of the oxide layer on the metal surface with coating protection is reduced by about 30% compared with that on the metal surface without coating protection. At the same time, in the coated area, the surface temperature during forging is 20-30 °C higher than that in the uncoated area, and the protective and heat-insulating properties are average.

[0089] The coating protection effects of the above examples and comparative examples are shown in Table 3 in detail.

[0090] Table 1

[0091]

[0092]

[0093] Table 2

[0094] parts by weight <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[B2O3]]> <![CDATA[Na2O]]> BaO <![CDATA[Bi2O3]]> PbO <![CDATA[Sb2O3]]> Example 1 8 3 10 3 35 20 13 8 Example 2 10 3 10 2 30 30 10 5 Example 14 5 1 5 0 25 20 10 5 Example 15 6 1 8 1 25 20 10 5 Example 16 8 3 13 3 30 25 15 8 Example 17 10 4 15 5 35 30 20 10

[0095] Table 3

[0096]

[0097]

[0098] As can be seen from the above, the protective and heat-insulating coatings of the embodiments of the present invention can be directly coated on the metal surface with a surface temperature not higher than 1000°C. The low-melting-point components therein can enable the protective and heat-insulating coatings to quickly melt and firmly adhere to the surface of the red-hot metal forging when contacting it, and rapidly form a continuous, dense and uniform glass film. After being continuously heated in the furnace along with the forging, the high-melting-point components in the protective and heat-insulating coatings will gradually melt, so that the glass film formed on the surface of the forging can continuously and stably exist, thereby isolating the influence of harmful gases on the forging throughout the entire heat process and achieving a good protective effect. At the same time, the formed glass film also has good heat insulation and heat preservation effects, which can reduce the temperature drop of the workpiece, extend the forging time, reduce the number of forging heats during the hot working processes such as forging after the metal forging is heated, thereby improving the production efficiency and the quality of the forging and reducing the forging cost.

[0099] The foregoing are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A protective and heat-insulating coating that can be applied to red-hot metal, characterized in that, The red-hot metal is a metal with a surface temperature of 600-1000° C.; the protective thermal insulation coating comprises, by weight, 5-15 parts of glass powder, 5-20 parts of Al2O3, 2-10 parts of SiO2, 2-5 parts of ZrB2, 1-10 parts of SiC, 5-15 parts of Cr2O3, 1-5 parts of Cr3C2, 10-40 parts of a binder and 10-20 parts of water, and the protective thermal insulation coating further comprises 1-5 parts of kaolin and 5-10 parts of sericite; Wherein, the glass powder is composed of 5 to 10 parts of SiO2, 1 to 4 parts of Al2O3, 5 to 15 parts of B2O3, 0 to 5 parts of Na2O, 25 to 35 parts of BaO, 20 to 30 parts of Bi2O3, 10 to 20 parts of PbO and 5 to 10 parts of Sb2O3 in parts by weight; Wherein, the binder comprises 10 to 20 parts of potassium water glass and 10 to 20 parts of silica sol, and the modulus of the potassium water glass is 2 to 3.

2. The protective and heat-insulating coating according to claim 1, characterized in that, In parts by weight, the protective thermal insulation coating includes 7 to 15 parts of the glass powder, 10 to 20 parts of Al2O3, 5 to 10 parts of SiO2, 2 to 4 parts of ZrB2, 1 to 6 parts of SiC, 8 to 13 parts of Cr2O3, 1 to 3 parts of Cr3C2, 20 to 30 parts of the binder and 15 to 20 parts of water.

3. The protective and heat-insulating coating according to claim 1 or 2, characterized in that, In terms of weight, the glass powder consists of 6 to 8 parts of SiO2, 1 to 3 parts of Al2O3, 8 to 13 parts of B2O3, 1 to 3 parts of Na2O, 25 to 30 parts of BaO, 20 to 25 parts of Bi2O3, 10 to 15 parts of PbO and 5 to 8 parts of Sb2O3.

4. The protective and heat-insulating coating according to claim 1 or 2, characterized in that, The material of the red hot metal includes one or more of steel, titanium, titanium alloy and high temperature alloy.

5. The protective and heat-insulating coating according to claim 4, characterized in that, When the material of the red-hot metal is the steel, the protective thermal insulation coating comprises, by weight, 7 to 9 parts of the glass powder, 17 to 20 parts of Al2O3, 5 to 7 parts of SiO2, 3 to 4 parts of ZrB2, 4 to 6 parts of SiC, 11 to 13 parts of Cr2O3, 2 to 3 parts of Cr3C2, 25 to 30 parts of the binder and 15 to 17 parts of water; When the material of the red-hot metal is the titanium and / or the titanium alloy, the protective thermal insulation coating comprises, by weight, 13 to 15 parts of the glass powder, 10 to 12 parts of Al2O3, 8 to 10 parts of SiO2, 2 to 3 parts of ZrB2, 1 to 2 parts of SiC, 8 to 10 parts of Cr2O3, 1 to 2 parts of Cr3C2, 20 to 25 parts of the binder and 18 to 20 parts of water; When the material of the red-hot metal is the high-temperature alloy, the protective thermal insulation coating includes, by weight, 10 to 13 parts of the glass powder, 13 to 16 parts of Al2O3, 6 to 8 parts of SiO2, 3 to 4 parts of ZrB2, 4 to 6 parts of SiC, 10 to 12 parts of Cr2O3, 2 to 3 parts of Cr3C2, 25 to 30 parts of the binder and 16 to 18 parts of water.

6. The protective and heat-insulating coating according to claim 4, characterized in that, The steel includes 0Cr18Ni9 and / or 1Cr18Ni9Ti, the titanium alloy includes TC4 and / or TC11, and the superalloy includes GH141 and / or GH718.

7. A protective and heat-insulating method for the forging process of red-hot metal, characterized in that, Weigh and mix the components of the protective and heat-insulating coating according to any one of claims 1 to 6, carry out ball milling and aging in sequence, then coat on the surface of the red-hot metal. After the coating formed by the protective and heat-insulating coating dries, forge it along with the red-hot metal.

8. The protective and heat-insulating method according to claim 7, characterized in that, The ball-to-material ratio of the ball milling is (2 - 4):1, the rotation speed is 50 - 100 revolutions / min, and the time is 10 - 14 h; and / or the aging time is 0.5 - 2 days.

9. The protective and heat-insulating method according to claim 7, characterized in that, The coating is spraying or brushing; the coating thickness of the protective and heat-insulating coating is 0.2 to 1 mm, and the coating dosage is 0.25 to 1 kg / m 2 .

10. The protective and heat-insulating method according to claim 7, characterized in that, When the material of the red-hot metal is steel, the heating temperature of the forging is 600 - 1300 °C, and the heat preservation time is 25 - 40 h; When the material of the red-hot metal is titanium and / or titanium alloy, the heating temperature of the forging is 600 - 1200 °C, and the heat preservation time is 20 - 30 h; When the material of the red-hot metal is superalloy, the heating temperature of the forging is 600 - 1200 °C, and the heat preservation time is 20 - 30 h.

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