Low-temperature high-toughness nickel-based welding rod and preparation method thereof

Abstract

The invention belongs to the technical field of welding materials, and particularly relates to a low-temperature high-toughness nickel-based welding rod and a preparation method thereof. The nickel-based welding rod comprises a core wire, a rare earth modified graphene coating and a coating, wherein the surface of the core wire is coated with the rare earth modified graphene coating, and the surface of the rare earth modified graphene coating is coated with the coating. The preparation method of the rare earth modified graphene comprises the following steps: adding graphene oxide and yttrium chloride hexahydrate into water for hydrothermal reaction to obtain a modified graphene precursor; and calcining the modified graphene precursor in an inert gas atmosphere to obtain the rare earth modified graphene. The rare earth modified graphene coated on the surface of the core wire can improve the arc stability, and also can be used as a strengthening phase in cladding metal to improve the strength and toughness of a welding seam.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding materials, and particularly relates to a low-temperature and high-toughness nickel-based electrode and a preparation method thereof. Background Art

[0002] In key industrial fields such as heavy machinery, shipbuilding, and energy equipment, ductile iron and gray iron have become the preferred materials for core components such as engine blocks, gearboxes, and machine tool beds due to their excellent shock absorption, wear resistance, and outstanding casting performance. However, cast iron welding technology has long faced three major technical bottlenecks: First, the carbon content of cast iron (2.11% - 4.0%) is much higher than that of steel, and hard and brittle martensite structures are easily formed during welding, with the probability of cracks occurring after weld cooling being over 80%; Second, when rapidly cooled, the weld metal is prone to form high-hardness white cast iron structures, resulting in brittle fracture of the weld and extremely poor machinability; Third, cast iron has poor thermal conductivity, and uneven heat input during welding easily causes coarsening of the microstructure in the heat-affected zone (HAZ), significantly reducing the toughness of the joint. These technical problems lead to the service life of cast iron welded repair parts being less than 1 / 3 of the original parts, and major equipment repairs rely on imported welding materials or directly scrapping the equipment, causing huge losses to the global industrial field every year.

[0003] In this context, nickel-based electrodes stand out due to their unique properties. The nickel element can form a stable Ni3C phase with carbon, effectively reducing the free carbon concentration and inhibiting the formation of hard and brittle martensite; at the same time, the thermal expansion coefficient of nickel-based alloys is close to that of cast iron, significantly reducing the welding residual stress and reducing the crack tendency by more than 60%. However, with the development of technology, the requirements for the low-temperature toughness of nickel-based electrodes in the fields of liquefied natural gas (LNG) storage tanks and polar offshore platforms are getting higher and higher. In addition, the application of nickel-based electrodes still has limitations: they are extremely sensitive to welding parameters (such as current, voltage, and preheating temperature), have extremely high requirements for arc stability, and are prone to porosity or lack of fusion during operation, which limits their large-scale promotion.

[0004] Therefore, there is an urgent need for nickel-based electrodes with excellent low-temperature toughness, stable arcs, and excellent mechanical properties. Summary of the Invention

[0005] The first object of the present invention is to provide a low-temperature and high-toughness nickel-based electrode, which has excellent high-temperature stability, can effectively control the hydrogen content in the weld, and improve the weld toughness.

[0006] The second object of the present invention is to provide a preparation method for a low-temperature and high-toughness nickel-based electrode.

[0007] To achieve the above objects, the technical solution adopted by the present invention is:

[0008] A low-temperature and high-toughness nickel-based welding electrode, the nickel-based welding electrode comprising a welding core, a rare-earth modified graphene coating coated on the surface of the welding core, and a coating coated on the surface of the rare-earth modified graphene coating;

[0009] The preparation method of the rare-earth modified graphene comprises the following steps:

[0010] (1) Adding graphene oxide and yttrium chloride hexahydrate into water, stirring, standing, and then carrying out a hydrothermal reaction. After suction filtration, washing, and drying, a modified graphene precursor is obtained;

[0011] (2) Calcining the modified graphene precursor in an inert gas atmosphere to obtain the rare-earth modified graphene.

[0012] Further, in step (1), the mass ratio of the graphene oxide, yttrium chloride hexahydrate, and water is 1:(1.5 - 2):(400 - 600); the stirring time is 2 - 4 h; the standing time is 20 - 24 h; the temperature of the hydrothermal reaction is 100 - 120 °C, and the time is 10 - 12 h.

[0013] Further, in step (2), the calcination temperature is 800 - 900 °C, and the time is 1 - 2 h.

[0014] Further, the coating is composed of powder and a binder; the binder is composed of the following raw materials: 70 - 75 wt% of sodium-potassium water glass, 17 - 20 wt% of sodium carboxymethyl cellulose, and 8 - 10 wt% of a binding aid;

[0015] The preparation method of the binding aid comprises the following steps:

[0016] (a) Adding tridecafluorooctyltriethoxysilane, sodium dodecyl sulfate, and sodium persulfate into water and stirring to obtain a pre-emulsion;

[0017] (b) Heating and reacting the pre-emulsion. After the reaction, cooling to room temperature and adding butyl acrylate and hexafluorobutyl methacrylate, and then heating to 70 - 85 °C and adding sodium thiosulfate and reacting for 1 - 2 h to obtain the binding aid.

[0018] Further, in step (a), the mass ratio of the tridecafluorooctyltriethoxysilane, sodium dodecyl sulfate, sodium persulfate, and water is (7 - 10):(0.8 - 1.2):(0.2 - 0.4):100.

[0019] Further, in step (b), the temperature of the heating reaction is 60 - 80 °C, and the time is 1 - 2 h; the mass ratio of the pre-emulsion, butyl acrylate, hexafluorobutyl methacrylate, and sodium thiosulfate is 100:(30 - 60):(5 - 8):(0.5 - 0.8).

[0020] Further, the medicinal powder is composed of the following raw materials: rutile: 20 - 33 wt%, marble: 8 - 12 wt%, chromium powder: 23 - 28 wt%, potassium cryolite 7 - 14 wt%, electrolytic manganese 8 - 12 wt%, atomized iron powder 5 - 8 wt%, molybdenum powder 3 - 6 wt%, barium carbonate 2 - 5 wt%, lanthanum fluoride 1 - 2 wt%, dehydrated quartz sand 1 - 2 wt%; the mass ratio of the medicinal powder to the binder is (3 - 4):1.

[0021] The preparation method of the above-mentioned low-temperature and high-toughness nickel-based electrode includes the following steps:

[0022] (S1) Add rare-earth modified graphene into water to make a suspension. After preheating the welding core, spray the suspension on the surface of the welding core to form a rare-earth modified graphene coating;

[0023] (S2) Mix each raw material component of the medicinal powder, and then add a binder and stir to obtain a coating for the electrode covering;

[0024] (S3) Apply the coating for the electrode covering on the surface of the rare-earth modified graphene coating to form an electrode covering, and perform a drying treatment to obtain the low-temperature and high-toughness nickel-based electrode.

[0025] Further, in step (S1), the concentration of the suspension is 1 - 1.5 mg / mL; the preheating temperature is 300 - 400 °C; the thickness of the rare-earth modified graphene coating is 50 - 100 μm.

[0026] Furthermore, in step (S1), the spraying parameters are: spray gun power 30 - 35 kW, current 700 - 750 A, voltage 40 - 50 V, air pressure 0.5 - 0.9 MPa, gas flow rate 50 - 80 L / min, suspension feeding flow rate 20 - 40 mL / min, spray gun moving speed 100 - 150 mm / s, and the number of spraying cycles is 40 - 60 times.

[0027] Further, in step (S3), the drying temperature is 120 - 150 °C, and the time is 3 - 5 h; the electrode covering accounts for 20 - 30% of the total mass of the electrode.

[0028] The beneficial technical effects of the present invention are as follows:

[0029] 1. The present invention coats rare-earth modified graphene on the nickel-based alloy welding core. By modifying graphene with rare-earth compounds, the dispersibility of graphene and its bonding property with the metal matrix can be improved, the welding stability of the coating can be enhanced, and the strength and toughness of the weld seam can be increased. This improvement also enables an increase in the addition amount of rare-earth, further reducing the impurities in the clad metal, and thus enhancing the mechanical properties of the weld seam. The present invention adds a bonding aid to the coating binder. The bonding aid is prepared by forming a pre-emulsion from tridecafluorooctyltriethoxysilane and sodium dodecyl sulfate under the catalysis of sodium persulfate, and then reacting the pre-emulsion with butyl acrylate and hexafluorobutyl methacrylate. Butyl acrylate has good film-forming properties, which can improve the moisture absorption resistance of the welding rod coating. The compounding with organosilicon can improve the water resistance, adhesion and thermal stability of the welding rod, reduce the water content of the coating, and thus reduce the diffusible hydrogen content in the weld metal, prevent the occurrence of hydrogen-induced delayed cracks, and improve the mechanical properties such as the toughness and strength of the weld seam.

[0030] 2. The present invention provides a preparation method for a nickel-based welding rod with low temperature and high toughness, and its preparation process is simple, which is beneficial to large-scale production. Specific Embodiments

[0031] The following content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should all be regarded as belonging to the protection scope of the present invention. The specific conditions not specified in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, unless otherwise specified, are all conventional products obtained through commercial channels.

[0032] The nickel-based welding core described in the present invention can be conventionally selected from commercially available welding cores without special requirements. The nickel-based welding cores in the following examples and comparative examples are NiCrMo-3 nickel-based alloys, and their components are: Cr: 20 - 23 wt%, Mo: 8 - 10 wt%, Nb: 3 - 4 wt%, Fe: ≤5 wt%, and the balance is Ni.

[0033] (I) Examples

[0034] Example 1

[0035] Example 1 provides a nickel-based welding rod with low temperature and high toughness, including a welding core, a rare-earth modified graphene coating coated on the surface of the welding core, and a coating coated on the surface of the rare-earth modified graphene coating.

[0036] The specific preparation process of the above rare-earth modified graphene is as follows:

[0037] (1) Add graphene oxide and yttrium chloride hexahydrate to water in a ratio of 1:1.8:500, stir for 3 h, let it stand for 22 h after mixing evenly, carry out hydrothermal reaction at 110 °C for 11 h after standing, and after the reaction solution cools to room temperature, carry out suction filtration, water washing, and drying to obtain a modified graphene precursor;

[0038] (2) Calcinate the modified graphene precursor at 850 °C in a nitrogen atmosphere for 1.5 h to obtain rare-earth modified graphene.

[0039] The above-mentioned coating consists of powder and binder with a mass ratio of 3:1, wherein the binder consists of the following raw materials: sodium-potassium water glass 73 wt%, sodium carboxymethyl cellulose 18 wt%, and binder assistant 9 wt%; the powder consists of the following raw materials: rutile 23 wt%, marble 10 wt%, chromium powder 26 wt%, potassium cryolite 11 wt%, electrolytic manganese 10 wt%, atomized iron powder 7 wt%, molybdenum powder 5 wt%, barium carbonate 4 wt%, lanthanum fluoride 2 wt%, and dehydrated quartz sand 2 wt%.

[0040] The specific preparation process of the above-mentioned binder assistant is as follows:

[0041] (a) Add 1H,1H,2H,2H-perfluorooctyltriethoxysilane, sodium dodecyl sulfate, and sodium persulfate to water in a mass ratio of 8:1:0.3:100, stir for 1.25 h to obtain a pre-emulsion;

[0042] (b) Heat the pre-emulsion to 70 °C, react for 1.5 h, cool to room temperature after the reaction and add butyl acrylate and 1H,1H,2H,2H-hexafluorobutyl methacrylate, then heat to 80 °C and add sodium thiosulfate to react for 1.5 h to obtain a binder assistant. The mass ratio of the pre-emulsion, butyl acrylate, 1H,1H,2H,2H-hexafluorobutyl methacrylate, and sodium thiosulfate is 100:40:6:0.7.

[0043] Example 1 also provides a preparation method of the above-mentioned low-temperature and high-toughness nickel-based welding electrode. The specific preparation process is as follows:

[0044] (S1) Add rare-earth modified graphene to water to make a suspension with a concentration of 1.2 mg / mL. After preheating the welding core to 350 °C, use the plasma spraying method to spray the suspension on the surface of the welding core to form a rare-earth modified graphene coating with a thickness of 80 μm; the spraying parameters are: spray gun power 32 kW, current 720 A, voltage 45 V, air pressure 0.8 MPa, gas flow rate 70 L / min, suspension feeding flow rate 30 mL / min, spray gun moving speed 120 mm / s, and spraying cycle times 50 times;

[0045] (S2) Mix the raw material components of the powder evenly, then add the binder and stir to obtain a coating paste;

[0046] (S3) Coat the coating powder on the surface of the above rare earth modified graphene coating to form a coating, leave it to stand and dry in air, and then dry it at 130 °C for 4 h to obtain a low-temperature and high-toughness nickel-based welding electrode; the coating accounts for 25% of the total mass of the welding electrode.

[0047] Example 2

[0048] Example 2 provides a low-temperature and high-toughness nickel-based welding electrode, which includes a welding core, a rare earth modified graphene coating coated on the surface of the welding core, and a coating coated on the surface of the rare earth modified graphene coating.

[0049] The specific preparation process of the above rare earth modified graphene is as follows:

[0050] (1) Add graphene oxide and yttrium chloride hexahydrate to water in a ratio of 1:1.5:400, stir for 2 h, leave it to stand for 20 h after mixing evenly, carry out hydrothermal reaction at 100 °C for 10 h after standing, and finally obtain a modified graphene precursor through suction filtration, washing, and drying.

[0051] (2) Calcinate the modified graphene precursor in a nitrogen atmosphere at 800 °C for 1 h to obtain rare earth modified graphene.

[0052] The above coating is composed of coating powder and binder with a mass ratio of 4:1, and the binder is composed of the following raw materials: sodium-potassium water glass 70 wt%, sodium carboxymethyl cellulose 20 wt%, and binder assistant 10 wt%. The coating powder is composed of the following raw materials: rutile: 20 wt%, marble: 12 wt%, chromium powder: 28 wt%, potassium cryolite 14 wt%, electrolytic manganese 8 wt%, atomized iron powder 8 wt%, molybdenum powder 6 wt%, barium carbonate 2 wt%, lanthanum fluoride 1 wt%, and dehydrated quartz sand 1 wt%.

[0053] The specific preparation process of the above binder assistant is as follows:

[0054] (a) Add tridecafluorooctyltriethoxysilane, sodium dodecyl sulfate, and sodium persulfate to water in a mass ratio of 7:0.8:0.2:100, and stir for 1 h to obtain a pre-emulsion.

[0055] (b) Heat the pre-emulsion to 60 °C, react for 1 h, cool it to room temperature after the reaction, add butyl acrylate and hexafluorobutyl methacrylate, and then heat it to 70 °C and add sodium thiosulfate to react for 1 h to obtain a binder assistant. The mass ratio of the pre-emulsion, butyl acrylate, hexafluorobutyl methacrylate, and sodium thiosulfate is 100:30:5:0.5.

[0056] Example 2 also provides a preparation method of the above low-temperature and high-toughness nickel-based welding electrode, and the specific preparation process is as follows:

[0057] (S1) Add rare earth modified graphene to water to make a suspension with a concentration of 1 mg / mL. After preheating the welding core to 300 °C, spray the suspension onto the surface of the welding core by plasma spraying to form a rare earth modified graphene coating with a thickness of 50 μm. The spraying parameters are as follows: spray gun power 30 kW, current 700 A, voltage 40 V, air pressure 0.5 MPa, gas flow rate 50 L / min, suspension feeding flow rate 20 mL / min, spray gun moving speed 100 mm / s, and spraying cycle times 40 times;

[0058] (S2) Mix all the raw material components of the powder evenly, and then add a binder and stir to obtain the coating for the welding flux.

[0059] (S3) Apply the coating for the welding flux to the surface of the above rare earth modified graphene coating to form the welding flux, let it stand and dry, and then dry it at 120 °C for 3 h to obtain a low-temperature and high-toughness nickel-based welding electrode. The welding flux accounts for 20% of the total mass of the welding electrode.

[0060] Example 3

[0061] Example 3 provides a low-temperature and high-toughness nickel-based welding electrode, which includes a welding core, a rare earth modified graphene coating coated on the surface of the welding core, and a welding flux coated on the surface of the rare earth modified graphene coating;

[0062] The specific preparation process of the above rare earth modified graphene is as follows:

[0063] (1) According to the ratio of 1:2:600, add graphene oxide and yttrium chloride hexahydrate to water and stir for 4 h. After mixing evenly, let it stand for 24 h. After standing, carry out a hydrothermal reaction at 120 °C for 12 h, and finally obtain the modified graphene precursor through suction filtration, washing, and drying;

[0064] (2) Calcinate the modified graphene precursor in a nitrogen atmosphere at 900 °C for 2 h to obtain rare earth modified graphene.

[0065] The above welding flux is composed of powder and binder with a mass ratio of 3:1. The binder is composed of the following raw materials: sodium-potassium water glass 75 wt%, sodium carboxymethyl cellulose 17 wt%, and binder assistant 8 wt%. The powder is composed of the following raw materials: rutile: 33 wt%, marble: 8 wt%, chromium powder: 23 wt%, potassium cryolite 7 wt%, electrolytic manganese 12 wt%, atomized iron powder 5 wt%, molybdenum powder 3 wt%, barium carbonate 5 wt%, lanthanum fluoride 2 wt%, and dehydrated quartz sand 2 wt%.

[0066] The specific preparation process of the above binder assistant is as follows:

[0067] (a) Add tridecafluorooctyltriethoxysilane, sodium dodecyl sulfate, and sodium persulfate to water according to a mass ratio of 10:1.2:0.4:100 and stir for 1.5 h to obtain a pre-emulsion;

[0068] (b) Heat the pre-emulsion to 80 °C and react for 2 h. After the reaction, cool to room temperature and add butyl acrylate and hexafluorobutyl methacrylate. Then heat to 85 °C and add sodium thiosulfate and react for 2 h to obtain a bonding aid. The mass ratio of the pre-emulsion, butyl acrylate, hexafluorobutyl methacrylate, and sodium thiosulfate is 100:60:8:0.8.

[0069] Example 3 also provides a method for preparing the above-mentioned low-temperature high-toughness nickel-based electrode. The specific preparation process is as follows:

[0070] (S1) Add rare-earth modified graphene to water to make a suspension with a concentration of 1.5 mg / mL. After preheating the welding core to 400 °C, use the plasma spraying method to spray the suspension on the surface of the welding core to form a rare-earth modified graphene coating with a thickness of 100 μm. The spraying parameters are as follows: spray gun power 35 kW, current 750 A, voltage 50 V, air pressure 0.9 MPa, gas flow rate 80 L / min, suspension feeding flow rate 40 mL / min, spray gun moving speed 150 mm / s, and spraying cycle times 60 times;

[0071] (S2) Mix the raw material components of the powder evenly, and then add a binder and stir to obtain a coating for the welding flux;

[0072] (S3) Apply the coating for the welding flux to the surface of the above-mentioned rare-earth modified graphene coating to form a welding flux, let it stand and dry in the air, and then dry at 150 °C for 5 h to obtain a low-temperature high-toughness nickel-based electrode. The welding flux accounts for 30% of the total mass of the electrode.

[0073] (II) Comparative Examples

[0074] Comparative Example 1

[0075] Comparative Example 1 is basically the same as Example 1, except that in the preparation process of the nickel-based electrode, rare-earth modified graphene is replaced with a mixture of an equal amount of yttrium chloride hexahydrate and graphene oxide, that is, in step (S1), a mixed suspension of yttrium chloride hexahydrate and graphene oxide is sprayed on the surface of the welding core, and the dosages of yttrium chloride hexahydrate and graphene oxide are the same as those in Example 1.

[0076] Comparative Example 2

[0077] Comparative Example 2 is basically the same as Example 1, except that in the preparation process of the nickel-based electrode, rare-earth modified graphene is replaced with an equal amount of graphene oxide, that is, in step (S1), a suspension of graphene oxide is sprayed on the surface of the welding core.

[0078] Comparative Example 3

[0079] The content of Comparative Example 3 is basically the same as that of Example 1, and the difference lies in that: the bonding aid in Example 1 is omitted.

[0080] Comparative Example 4

[0081] The content of Comparative Example 4 is basically the same as that of Example 1, and the difference lies in that: the bonding aid in Example 1 is replaced with an equal amount of butyl acrylate.

[0082] (III) Test Examples

[0083] The low-temperature high-toughness nickel-based electrodes prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were used to detect the corresponding welding performance of 9Ni steel. The welding process parameters were: current 120 - 130 A, interpass temperature 120 - 130 °C, and number of layers 6 - 8 layers.

[0084] Mechanical properties: After welding, the yield strength, tensile strength, elongation after fracture, and impact performance at -196 °C of the deposited metal in each group were detected according to GB / T2652 - 2008 "Test Methods for Tensile of Welds and Deposited Metals", and the results are shown in Tables 1 - 2.

[0085] Table 1 Mechanical Properties of Deposited Metals of Electrodes in Examples and Comparative Examples

[0086] Group Yield strength ReL (MPa) Tensile strength Rm (MPa) Elongation A (%) Example 1 471 742 35 Example 2 467 740 32 Example 3 465 739 33 Comparative example 1 377 659 26 Comparative example 2 369 634 24 Comparative example 3 389 681 28 Comparative example 4 402 690 30

[0087] Table 2 Impact Performance at -196 °C of Electrodes in Examples and Comparative Examples

[0088] Group / Impact value (J) Weld center Fusion line Fusion line + 2mm Example 1 94 87 107 Example 2 92 86 105 Example 3 91 84 101 Comparative example 1 74 68 83 Comparative example 2 67 60 78 Comparative example 3 76 70 85 Comparative example 4 80 74 90

[0089] As can be seen from Tables 1 - 2, when welding with the low-temperature high-toughness nickel-based electrodes prepared in Examples 1 to 3 of the present invention, the weld has excellent mechanical strength and low-temperature toughness.

[0090] Compared with Example 1, in Comparative Example 1, the rare-earth modified graphene was replaced with a mixture of an equal amount of yttrium chloride hexahydrate and graphene oxide. In Comparative Example 2, the rare-earth modified graphene was replaced with an equal amount of graphene oxide. For the nickel-based welding electrodes prepared, both the mechanical properties of the clad metal and the low-temperature toughness deteriorated. Specific analysis shows that: Graphene has good electrical and thermal conductivity. As a coating, it can timely volatilize the heat generated during welding and stabilize the arc, preventing the welding rod coating from turning red and cracking. An appropriate amount of graphene can also act as a strengthening phase in the clad metal to improve the strength and toughness of the weld. However, the dispersibility of graphene and its interfacial bonding force with the nickel-based alloy are poor, making the preparation of the coating difficult and less stable. Moreover, excessive carbon is likely to generate embrittling phases in the weld metal, affecting the mechanical properties of the weld. In the present invention, a rare-earth modified graphene coating is prepared outside the nickel-based alloy welding core. By modifying graphene with rare-earth compounds, the dispersibility of graphene and its bonding property with the metal matrix can be improved, the welding stability of the coating can be enhanced, and the strength and toughness of the weld can be increased. At the same time, this improvement also allows for an increase in the addition amount of rare earth, further reducing the impurities in the clad metal and enhancing the low-temperature toughness.

[0091] Compared with Example 1, in Comparative Example 3, the binder additive in Example 1 was omitted, and in Comparative Example 4, the binder additive in Example 1 was replaced with an equal amount of butyl acrylate. During the welding process, there was also a decrease in the mechanical properties and low-temperature toughness of the nickel-based welding electrode. Specific analysis shows that: The binder additive of the present invention is prepared by forming a pre-emulsion from tridecafluorooctyltriethoxysilane and sodium dodecyl sulfate under the catalysis of sodium persulfate, and then reacting this pre-emulsion with butyl acrylate and hexafluorobutyl methacrylate. Butyl acrylate has good film-forming properties, can improve the moisture absorption resistance of the welding rod coating, and when combined with organosilicon, can improve the water resistance, adhesion, and thermal stability of the welding rod, reduce the water content of the coating, and thus reduce the diffusible hydrogen content in the weld metal, prevent the occurrence of hydrogen-induced delayed cracks, and improve the toughness of the weld.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. The basic principles and main features of the present invention have been described using specific implementation schemes above. Based on the present invention, some modifications or replacements can be made, but these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of protection required by the present invention.

Claims

1. A low-temperature and high-toughness nickel-based welding electrode, characterized in that, The nickel-based welding electrode includes a welding core, a rare-earth modified graphene coating coated on the surface of the welding core, and a coating on the surface of the rare-earth modified graphene coating; The preparation method of the rare-earth modified graphene includes the following steps: (1) Adding graphene oxide and yttrium chloride hexahydrate into water, stirring, standing, and then performing hydrothermal reaction. After suction filtration, washing, and drying, a modified graphene precursor is obtained; (2) Calcining the modified graphene precursor in an inert gas atmosphere to obtain the rare-earth modified graphene.

2. The low-temperature high-toughness nickel-based welding electrode according to claim 1, wherein In step (1), the mass ratio of the graphene oxide, yttrium chloride hexahydrate, and water is 1:(1.5 - 2):(400 - 600); the stirring time is 2 - 4 h; the standing time is 20 - 24 h; the temperature of the hydrothermal reaction is 100 - 120 °C, and the time is 10 - 12 h.

3. The low-temperature high-toughness nickel-based welding electrode according to claim 1, wherein In step (2), the calcining temperature is 800 - 900 °C, and the time is 1 - 2 h.

4. The low-temperature high-toughness nickel-based welding electrode according to claim 1, characterized in that, The coating consists of powder and a binder; the binder consists of the following raw materials: sodium-potassium water glass 70 - 75 wt%, sodium carboxymethylcellulose 17 - 20 wt%, and a binding aid 8 - 10 wt%; The preparation method of the binding aid includes the following steps: (a) Adding tridecafluoroctyltriethoxysilane, sodium dodecyl sulfate, and sodium persulfate into water and stirring to obtain a pre-emulsion; (b) Heating and reacting the pre-emulsion. After the reaction, it is cooled to room temperature and butyl acrylate and hexafluorobutyl methacrylate are added. Then it is heated to 70 - 85 °C and sodium thiosulfate is added to react for 1 - 2 h to obtain the binding aid.

5. The low-temperature high-toughness nickel-based welding electrode according to claim 4, characterized in that, In step (a), the mass ratio of the tridecafluoroctyltriethoxysilane, sodium dodecyl sulfate, sodium persulfate, and water is (7 - 10):(0.8 - 1.2):(0.2 - 0.4):

100.

6. The low-temperature high-toughness nickel-based welding electrode according to claim 4, characterized in that, In step (b), the temperature of the heating reaction is 60 - 80 °C, and the time is 1 - 2 h; the mass ratio of the pre-emulsion, butyl acrylate, hexafluorobutyl methacrylate, and sodium thiosulfate is 100:(30 - 60):(5 - 8):(0.5 - 0.8).

7. The cryogenic high-toughness nickel-based electrode according to claim 4, characterized in that, The powder consists of the following raw materials: rutile: 20 - 33 wt%, marble: 8 - 12 wt%, chromium powder: 23 - 28 wt%, potassium cryolite 7 - 14 wt%, electrolytic manganese 8 - 12 wt%, atomized iron powder 5 - 8 wt%, molybdenum powder 3 - 6 wt%, barium carbonate 2 - 5 wt%, lanthanum fluoride 1 - 2 wt%, dehydrated quartz sand 1 - 2 wt%; the mass ratio of the powder to the binder is (3 - 4):

1.

8. The preparation method of the low-temperature high-toughness nickel-based welding electrode according to claim 7, characterized in that, Including the following steps: (S1) Adding the rare-earth modified graphene into water to make a suspension. After preheating the welding core, the suspension is sprayed on the surface of the welding core to form a rare-earth modified graphene coating; (S2) Mixing the raw material components of the powder, and then adding the binder and stirring to obtain a coating for the coating; (S3) Coating the coating for the coating on the surface of the rare-earth modified graphene coating to form a coating, and performing a drying treatment to obtain the low-temperature and high-toughness nickel-based welding electrode.

9. The preparation method of the low-temperature high-toughness nickel-based welding electrode according to claim 8, wherein The concentration of the suspension described in step (S1) is 1 to 1.5 mg / mL; the preheating temperature is 300 to 400 °C; the thickness of the rare earth modified graphene coating is 50 to 100 μm.

10. The preparation method of the low-temperature high-toughness nickel-based welding electrode according to claim 8, characterized in that, The temperature of drying described in step (S3) is 120 to 150 °C, and the time is 3 to 5 h; the coating in the welding rod accounts for 20 - 30% of the total mass of the welding rod.