Low-temperature preparation method of high-corrosion-resistance multicomponent alloy infiltrated layer

Abstract

The invention provides a low-temperature preparation method of a high-corrosion-resistance multicomponent alloy infiltrated layer, and relates to the field of steel corrosion resistance, which comprises the following steps: step 1, substrate pretreatment: sequentially carrying out surface cleaning and surface roughening pretreatment processes on a steel substrate; secondly, plasma spraying is conducted, specifically, a multi-element alloy layer is prepared on the surface of the pretreated steel base body through the plasma spraying technology; and thirdly, sherardizing treatment is conducted, specifically, sherardizing is conducted on the surface of the multi-component alloy layer prepared in the second step through a mechanical energy auxiliary powder sherardizing technology, and the multi-component alloy sherardizing layer is obtained. The method prepares the multi-component alloy infiltrated layer on the steel surface at low temperature, is suitable for corrosion protection of steel, and has the characteristics of simple process, excellent wear resistance and corrosion resistance and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel corrosion resistance, and particularly relates to a low-temperature preparation method of high-corrosion-resistance multi-element alloy layer. BACKGROUND

[0002] Powder zinc infiltration refers to a surface strengthening technology that, under a high-temperature environment, a pretreated metal workpiece (usually a steel material) is placed into a uniform mixture of a main infiltrant, an activator, and an inert filler, and is heated together, so that corrosion-resistant elements such as zinc diffuse to the surface of the metal substrate to form a metallurgical bonding alloy layer; the powder zinc infiltration technology endows the workpiece with excellent wear resistance, corrosion resistance, and high-temperature oxidation resistance. With the increasingly harsh application environment of steel materials, the requirements for the protective performance of the powder zinc infiltration layer are becoming more and more stringent; at present, researchers are committed to introducing one or two (such as aluminum, chromium, magnesium, nickel, manganese, and titanium) high-corrosion-resistant metal elements to prepare a multi-element alloy layer, which effectively improves the wear resistance, corrosion resistance, and high-temperature oxidation resistance of the alloy layer through the complementary and synergistic effects of multiple elements. For example, Chinese patent document CN111850459A discloses a high-corrosion-resistance powder zinc infiltrant, which adds aluminum, magnesium, and rare earth compounds to zinc alloy powder, so that zinc-magnesium-aluminum alloy powder is formed between magnesium and aluminum and zinc, so that zinc and magnesium further synergistically enter the infiltration layer structure during the powder infiltration process, forming a high-corrosion-resistance alloy phase, and promoting the corrosion products to change from loose structures of ordinary zinc infiltration to dense structures during the corrosion process, thereby greatly improving the corrosion resistance of the steel part; by adding rare earth compounds, the magnesium alloy is coated, so that the final zinc alloy powder particles are composed of zinc phase and magnesium alloy phase, which facilitates the synergistic effect of zinc and magnesium into the infiltration layer structure in the subsequent powder zinc infiltration process.

[0003] However, the melting points of aluminum, chromium, magnesium, nickel, manganese, titanium, and other elements are significantly higher than the melting point of Zn (419.5℃), so it is usually necessary to perform alloying at a temperature higher than the melting point of zinc (for example, in patent CN111850459A, alloy powder is melted at 500-900℃); high temperature not only easily causes zinc powder to melt and agglomerate, resulting in alloy powder adhesion, affecting the particle size and uniformity of the subsequent alloy powder, and further affecting the uniformity of the infiltration layer structure, but also easily damages the microstructure of the alloy powder, leading to a decrease in the mechanical properties of the infiltration layer. In addition, the melting point of corrosion-resistant metals such as nickel is very high (generally around 1453℃), and it is not possible to directly add nickel metal powder to the zinc infiltrant to obtain a corrosion-resistant multi-element alloy layer (if the melting state of nickel is to be achieved, zinc will have reached the gasification state, and the gasification temperature of zinc is about 907℃), so the corrosion resistance of the alloy infiltration layer cannot be effectively improved. SUMMARY

[0004] In view of the problems existing in the prior art, the purpose of the present application is to provide a low-temperature preparation method of high-corrosion-resistant multi-element alloy layer, which is suitable for corrosion protection of steel and iron and has the characteristics of simple process, excellent wear and corrosion resistance, etc.

[0005] The purpose of the present application is achieved by the following technical solutions: The low-temperature preparation method of high-corrosion-resistant multi-element alloy layer comprises the following steps: Step 1: pretreatment of the substrate: sequentially performing surface cleaning and surface roughening pretreatment processes on the steel substrate; Step 2: plasma spraying: preparing a multi-element alloy layer on the surface of the pretreated steel substrate by using a plasma spraying process, and the multi-element alloy layer adopts any one of NiCrAlY and NiCoCrAlY metal coatings; Step 3: zinc infiltration treatment: performing zinc infiltration on the surface of the multi-element alloy layer prepared in step 2 by using a mechanical energy assisted powder zinc infiltration process to obtain a multi-element alloy layer.

[0006] Based on further optimization of the above scheme, the surface cleaning comprises degreasing and oil removal, rust removal and oxide scale removal; the degreasing and oil removal: placing the steel substrate in an organic solvent and cleaning the steel substrate by using ultrasonic cleaning, taking out the steel substrate after cleaning and wiping the surface of the steel substrate, and the organic solvent adopts any one of acetone and ethanol; the rust removal and oxide scale removal: removing the rust and oxide scale on the surface of the steel substrate by mechanical grinding or chemical pickling.

[0007] Based on further optimization of the above scheme, the surface roughening specifically comprises: first, roughening the surface of the steel substrate by sand blasting, the sand blasting pressure is 0.4-0.7 MPa, and the roughness Ra after sand blasting is 3-10 μm; then, blowing the surface of the steel substrate after sand blasting with anhydrous and oil-free compressed air to remove surface dust and sand particles; then, wiping the surface of the steel substrate with an organic solvent such as acetone or ethanol; finally, drying the surface of the steel substrate by hot air drying to avoid water residue on the surface of the substrate, and the temperature of the hot air drying is 45-50℃.

[0008] Based on further optimization of the above scheme, the plasma spraying process parameters specifically comprise: a spraying power of 28-35 KW, a spraying distance of 150-200 mm, and a powder feeding rate of 10-50 g / min; and the thickness of the multi-element alloy layer is 10-20 μm.

[0009] Based on further optimization of the above scheme, the parameters of the mechanical energy assisted powder sherardizing process are: sherardizing with pulsed temperature, specifically: first quickly heating to 350-360°C, and keeping at 350-360°C for 28-30min, then heating to 395-405°C at a rate of 5-10°C / min, and keeping at 395-405°C for 4-6h, and finally cooling to 350-360°C at a rate of 1-3°C / min, and keeping at 350-360°C for 18-22min; mechanical assistance is specifically: rotating the furnace body and the furnace body speed is 1-5r / min.

[0010] Based on further optimization of the above scheme, the penetrants in the mechanical energy assisted powder sherardizing process include: zinc powder, indium powder, activator, ZnCl2 powder, B2O3 powder, Nb2O5 powder and Al2O3 powder; the mass percentages between them are: 50~60wt.%, 1~3wt.%, 2~6wt.%, 4~6wt.%, 4~8wt.%, 12~16wt.%, and the rest is Al2O3 powder.

[0011] The present invention uses zinc powder and ZnCl₂ powder as a composite zinc source to increase the initial zinc ion diffusion rate and ensure the zinc ion diffusion depth. Driven by concentration gradients and lattice thermal vibrations, the zinc ions continuously diffuse into the multicomponent alloy layer and the steel substrate. The zinc ions and the multicomponent alloy layer form a dense multicomponent Zn-X (X is Ni, Cr, Al, and Co) alloy surface layer, effectively filling the gaps in the plasma-sprayed layer. Simultaneously, as the zinc ions diffuse, they react with the iron atoms of the substrate to form a Zn-Fe phase between the Zn-X alloy layer and the substrate, transforming the mechanical bond between the plasma-sprayed layer and the substrate into a metallurgical bond, ensuring the long-term protective performance of the zinc-diffused layer. Furthermore, during the zinc ion diffusion process, the rare earth element Y in the multicomponent alloy layer segregates at the grain boundaries, hindering the nucleation and growth of the alloy's brittle phase, thereby refining the grains. It also acts as a pinning force, hindering grain boundary sliding and increasing the hardness of the alloyed layer.

[0012] The application forms a glass phase in the infiltrant by the B2O3 powder with low melting point, further reduces the interfacial tension of zinc powder and zinc salt (ZnCl2 powder), promotes their activation at low temperature, and the B2O3 powder reacts with alloy elements in the plasma sprayed multi-element alloy layer under heating conditions to form "active sites" for zinc atom diffusion, effectively reduces the diffusion activation energy, promotes zinc diffusion, and reduces the formation of infiltration layer cracks; the "lattice distortion effect" of the composite powder in the infiltrant after infiltrating into the coating increases the diffusion driving force of zinc atoms and ensures the structural stability of the coating, at the same time, the composite powder forms a composite interface layer, cooperates with the alloy elements in the multi-element alloy layer, forms a multi-element alloy phase, not only further fills the voids of the plasma sprayed layer, but also effectively increases the interfacial bonding force between the coating and the substrate, and between the coating and the zinc infiltration layer. In addition, through the cooperation of the composite powder, not only the direct contact between zinc atoms and the iron on the surface of the substrate is effectively promoted, and the formation of Zn-Fe phase is accelerated, but also the excessive diffusion of iron atoms in the substrate is inhibited, avoiding the loosening of Zn-Fe, and the direct contact between the multi-element alloy layer and the activator is also effectively avoided to cause element loss.

[0013] Based on the further optimization of the above scheme, the activator is a combination of urea, tetraethylammonium chloride and ethylenediaminetetraacetic acid disodium salt, and the mass ratio among them is 4.5-5.5:1.5-2.5:2.5-3.5.

[0014] The conventional zinc infiltrant uses ammonium chloride as an activator, and the chloride ion generated by the thermal decomposition of ammonium chloride reacts with the surface of steel to form ferrous chloride, which promotes the replacement reaction of zinc to achieve the purpose of zinc infiltration; however, the HCl gas generated by the decomposition of ammonium chloride is corrosive, which can easily cause corrosion of the multi-element alloy layer generated by plasma spraying, and further cause functional damage to the multi-element alloy layer, affecting the progress of the zinc infiltration process and the uniformity of the zinc infiltration. The specific activator of the application not only forms a reducing atmosphere under heating conditions to avoid oxidation of the multi-element alloy layer during the zinc infiltration process, but also effectively forms a complex to promote the adsorption and diffusion of zinc atoms; in addition, it can also chelate metal ions, further inhibit the agglomeration of zinc powder, promote the dissolution and transport of zinc ions, and further improve the uniformity of the infiltration layer. Moreover, the specific activator composed of urea, tetraethylammonium chloride and ethylenediaminetetraacetic acid disodium salt does not produce corrosive gas during the heating process, thereby effectively avoiding corrosion of the multi-element alloy layer and ensuring the functional integrity of the multi-element alloy layer sprayed by plasma.

[0015] The following are the technical effects of the application scheme: The present invention prepares a multi-component alloy layer of NiCrAlY or NiCoCrAlY by plasma spraying, and then uses mechanical energy to assist the powder sherardizing process to achieve sherardization on the surface of the steel substrate of the multi-component alloy layer. Not only does the diffused zinc fill the gaps in the multi-component alloy layer to form a highly corrosion-resistant and dense multi-component alloy surface layer, but the continuously diffused zinc forms a Zn-Fe phase with the iron atoms on the surface of the steel substrate, ensuring the interfacial bonding strength and protective performance between the steel substrate and the sprayed layer, thereby improving the overall corrosion resistance of the steel substrate. In addition, the present invention cooperates with a specific multi-component alloy layer and a sherardizing process, and through the segregation of the rare earth Y element in the multi-component alloy layer at the grain boundary, effectively hinders the growth of the nucleation of the alloy brittle phase and achieves the purpose of grain refinement. At the same time, it can play a pinning role, hinder grain boundary sliding, and improve the hardness of the alloyed sherardized layer. The multi-component alloy sherardized layer component prepared by the present invention has excellent wear resistance and corrosion resistance, high bonding strength between the steel substrate and the multi-component alloy layer, strong integration, and good overall protective performance. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0017] Example 1: A low-temperature preparation method for a highly corrosion-resistant multi-element alloy diffusion layer comprises: Step 1: Substrate pretreatment: The steel substrate is subjected to a pretreatment process of surface cleaning and surface roughening in sequence; Surface cleaning includes degreasing, deoiling, rust removal and oxide scale removal; degreasing and deoiling: place the steel substrate in an organic solvent and use ultrasonic cleaning to clean the steel substrate. After cleaning, take out the steel substrate and wipe its surface dry. The organic solvent used is acetone; rust and oxide scale removal: remove rust and oxide scale from the surface of the steel substrate by mechanical grinding or chemical pickling (select according to the actual situation of rust and oxide scale on the steel surface).

[0018] First, the surface of the steel substrate was roughened by sandblasting with a sandblasting pressure of 0.4 MPa and a roughness Ra of 3 μm after sandblasting. Then, the surface of the steel substrate after sandblasting was purged with water-free and oil-free compressed air to remove surface dust and sand particles. The steel surface was then wiped with acetone. Finally, the surface of the steel substrate was dried by hot air drying to avoid residual moisture on the substrate surface. The hot air drying temperature was 45°C.

[0019] Step two, plasma spraying: using plasma spraying process to prepare a multi-element alloy layer on the surface of the pretreated steel substrate, and the multi-element alloy layer uses a NiCrAlY metal coating; the spraying power is 28 KW, the spraying distance is 150 mm, and the powder feeding rate is 10 g / min; the thickness of the multi-element alloy layer is 10 μm.

[0020] Step three, zinc infiltration treatment: using a mechanical energy assisted powder zinc infiltration process to infiltrate zinc on the surface of the multi-element alloy layer prepared in step two to obtain a multi-element alloy infiltration layer; the parameters of the mechanical energy assisted powder zinc infiltration process are as follows: the zinc infiltration is carried out in a pulse mode, specifically: first, rapidly heating to 350 ℃ and keeping at 350 ℃ for 30 min, then heating to 395 ℃ at a rate of 5 ℃ / min and keeping at 395 ℃ for 6 h, finally, cooling to 350 ℃ at a rate of 1 ℃ / min and keeping at 350 ℃ for 22 min; the mechanical assistance is specifically that the furnace body is rotated at a speed of 1 r / min.

[0021] The infiltrant in the mechanical energy assisted powder zinc infiltration process includes: zinc powder, indium powder, activator, ZnCl2 powder, B2O3 powder, Nb2O5 powder and Al2O3 powder; the mass percentage among them is: 50wt.%, 1wt.%, 2wt.%, 4wt.%, 4wt.%, 12wt.%, and the rest is Al2O3 powder. Among them, the activator uses a combination of urea, tetraethylammonium chloride and ethylenediaminetetraacetic acid disodium salt, and the mass ratio among them is 4.5:1.5:2.5.

[0022] Example 2: A low-temperature preparation method of a high-corrosion-resistant multi-element alloy infiltration layer, comprising: Step one, substrate pretreatment: sequentially performing surface cleaning and surface roughening pretreatment processes on the steel substrate; The surface cleaning includes degreasing, rust removal and oxide scale removal; the degreasing: placing the steel substrate in an organic solvent and cleaning the steel substrate by ultrasonic cleaning, then taking out the steel substrate and wiping the surface dry, and the organic solvent is ethanol; the rust removal and oxide scale removal: removing the rust and oxide scale on the surface of the steel substrate by mechanical grinding or chemical pickling (selected according to the actual situation of the rust and oxide scale on the surface of the steel).

[0023] First, the surface of the steel substrate is roughened by sandblasting, the sandblasting pressure is 0.6 MPa, and the roughness Ra after sandblasting is 6.5 μm; then, the surface of the sandblasted steel substrate is blown off by using compressed air without water and oil to remove the surface dust and sand particles; then, the steel surface is wiped with ethanol; finally, the steel substrate surface is dried by hot air drying to avoid water residue on the substrate surface, and the temperature of the hot air drying is 47 ℃.

[0024] Step two, plasma spraying: using plasma spraying process to prepare a multi-element alloy layer on the surface of the pretreated steel substrate, and the multi-element alloy layer uses a NiCoCrAlY metal coating; the spraying power is 32 KW, the spraying distance is 175 mm, and the powder feeding rate is 30 g / min; the thickness of the multi-element alloy layer is 15 μm.

[0025] Step three, zinc infiltration treatment: using a mechanical energy assisted powder zinc infiltration process to infiltrate zinc on the surface of the multi-element alloy layer prepared in step two to obtain a multi-element alloy infiltration layer; the parameters of the mechanical energy assisted powder zinc infiltration process are as follows: the zinc infiltration is carried out in a pulse mode, specifically: first, rapidly heating to 355℃ and keeping at 355℃ for 29 min, then heating to 400℃ at a rate of 7℃ / min and keeping at 400℃ for 5 h, finally, cooling to 355℃ at a rate of 2℃ / min and keeping at 355℃ for 20 min; the mechanical assistance is specifically that the furnace body is rotated at a speed of 3 r / min.

[0026] The infiltrant in the mechanical energy assisted powder zinc infiltration process includes: zinc powder, indium powder, activator, ZnCl2 powder, B2O3 powder, Nb2O5 powder and Al2O3 powder; the mass percentage among them is: 55wt.%, 2wt.%, 4wt.%, 5wt.%, 6wt.%, 14wt.%, and the rest is Al2O3 powder. Among them, the activator uses a combination of urea, tetraethylammonium chloride and ethylenediaminetetraacetic acid disodium salt, and the mass ratio among them is 5:2:3.

[0027] Example 3: A low-temperature preparation method of a high-corrosion-resistant multi-element alloy infiltration layer, comprising: Step one, substrate pretreatment: sequentially performing surface cleaning and surface roughening pretreatment processes on the steel substrate; The surface cleaning includes degreasing, rust removal and oxide scale removal; the degreasing: placing the steel substrate in an organic solvent and cleaning the steel substrate by ultrasonic cleaning, then taking out the steel substrate and wiping the surface dry, and the organic solvent is acetone; the rust removal and oxide scale removal: removing the rust and oxide scale on the surface of the steel substrate by mechanical grinding or chemical pickling (selected according to the actual situation of the rust and oxide scale on the surface of the steel).

[0028] First, roughening the surface of the steel substrate by sandblasting, the sandblasting pressure is 0.7 MPa, and the roughness Ra after sandblasting is 10 μm; then, blowing the surface of the sandblasted steel substrate with anhydrous and oil-free compressed air to remove surface dust and sand particles; then wiping the steel surface with ethanol; finally, drying the surface of the steel substrate by hot air drying to avoid water residue on the surface of the substrate, and the temperature of the hot air drying is 50℃.

[0029] Step two, plasma spraying: using plasma spraying process to prepare a multi-element alloy layer on the surface of the pretreated steel substrate, and the multi-element alloy layer uses a NiCrAlY metal coating; the spraying power is 35KW, the spraying distance is 200mm, and the powder feeding rate is 50g / min; the thickness of the multi-element alloy layer is 20μm.

[0030] Step three, zinc infiltration treatment: using a mechanical energy assisted powder zinc infiltration process to infiltrate zinc on the surface of the multi-element alloy layer prepared in step two to obtain a multi-element alloy infiltration layer; the parameters of the mechanical energy assisted powder zinc infiltration process are as follows: infiltrating zinc by pulse temperature, specifically: first rapidly heating to 360℃ and keeping at 360℃ for 28min, then heating to 405℃ at a rate of 10℃ / min and keeping at 405℃ for 4h, finally, cooling to 360℃ at a rate of 3℃ / min and keeping at 360℃ for 18min; the mechanical assistance is specifically that the furnace body is rotated at a speed of 5r / min.

[0031] The infiltrating agent in the mechanical energy assisted powder zinc infiltration process includes: zinc powder, indium powder, activator, ZnCl2 powder, B2O3 powder, Nb2O5 powder and Al2O3 powder; the mass percentage among them is: 60wt.%, 3wt.%, 6wt.%, 6wt.%, 7.5wt.%, 15wt.%, and the rest is Al2O3 powder. Among them, the activator uses a combination of urea, tetraethylammonium chloride and ethylenediaminetetraacetic acid disodium salt, and the mass ratio among them is 5.5:2.5:3.5.

[0032] Comparative example 1: A method for preparing a multi-element alloy infiltration layer, comprising: Step one, substrate pretreatment: consistent with step one in example 2.

[0033] Step two, plasma spraying: consistent with step two in example 2.

[0034] Step three, zinc infiltration treatment: using a mechanical energy assisted powder zinc infiltration process to infiltrate zinc on the surface of the multi-element alloy layer prepared in step two to obtain a multi-element alloy infiltration layer; the parameters of the mechanical energy assisted powder zinc infiltration process are as follows: rapidly heating to 400℃ and keeping at 400℃ for 6h; the mechanical assistance is specifically that the furnace body is rotated at a speed of 3r / min.

[0035] The formula of the infiltrating agent package in the mechanical energy assisted powder zinc infiltration process is consistent with example 2.

[0036] Comparative example 2: A method for preparing a multi-element alloy infiltration layer, comprising: Step one, substrate pretreatment: consistent with step one in example 2.

[0037] Step two, plasma spraying: consistent with step two in example 2.

[0038] Step three, zinc infiltration treatment: a mechanical energy assisted powder zinc infiltration process is used to infiltrate zinc on the surface of the multi-element alloy layer prepared in step two, to obtain a multi-element alloy infiltration layer; the parameters of the mechanical energy assisted powder zinc infiltration process are as follows: the zinc infiltration is performed at a pulse temperature, specifically: first, rapidly heat to 355℃ and keep at 355℃ for 29min, then heat to 400℃ at a rate of 7℃ / min and keep at 400℃ for 5h, finally, cool to 355℃ at a rate of 2℃ / min and keep at 355℃ for 20min; the mechanical assistance is specifically: rotating the furnace body and the rotation speed of the furnace body is 3r / min.

[0039] The infiltrant in the mechanical energy assisted powder zinc infiltration process includes: zinc powder, indium powder, activator, ZnCl2 powder, B2O3 powder, Nb2O5 powder and Al2O3 powder; the mass percentage among them is: 55wt.%, 2wt.%, 4wt.%, 5wt.%, 6wt.%, 14wt.%, and the rest is Al2O3 powder. Among them, the activator is ammonium chloride.

[0040] Comparative example 3: A preparation method of a multi-element alloy infiltration layer, comprising: Step one, substrate pretreatment: consistent with step one in example 2.

[0041] Step two, plasma spraying: consistent with step two in example 2.

[0042] Step three, zinc infiltration treatment: a mechanical energy assisted powder zinc infiltration process is used to infiltrate zinc on the surface of the multi-element alloy layer prepared in step two, to obtain a multi-element alloy infiltration layer; the parameters of the mechanical energy assisted powder zinc infiltration process are as follows: the zinc infiltration is performed at a pulse temperature, specifically: first, rapidly heat to 355℃ and keep at 355℃ for 29min, then heat to 400℃ at a rate of 7℃ / min and keep at 400℃ for 5h, finally, cool to 355℃ at a rate of 2℃ / min and keep at 355℃ for 20min; the mechanical assistance is specifically: rotating the furnace body and the rotation speed of the furnace body is 3r / min.

[0043] The infiltrant in the mechanical energy assisted powder zinc infiltration process includes: zinc powder, indium powder, activator, B2O3 powder, Nb2O5 powder and Al2O3 powder; the mass percentage among them is: 60wt.%, 2wt.%, 4wt.%, 6wt.%, 14wt.%, and the rest is Al2O3 powder. Among them, the activator is a combination of urea, tetraethylammonium chloride and ethylenediaminetetraacetic acid disodium salt, and the mass ratio among them is 5:2:3.

[0044] Comparative example 4: A method for preparing a multi-element alloyed layer, comprising: Step one, substrate pretreatment: consistent with step one in example 2.

[0045] Step two, plasma spraying: consistent with step two in example 2.

[0046] Step three, zinc infiltration treatment: a mechanical energy assisted powder zinc infiltration process is used to infiltrate zinc on the surface of the multi-element alloy layer prepared in step two, to obtain a multi-element alloyed layer; the parameters of the mechanical energy assisted powder zinc infiltration process are as follows: the zinc infiltration is performed at a pulse temperature, specifically: first, rapidly heat to 355℃ and keep at 355℃ for 29min, then heat to 400℃ at a rate of 7℃ / min and keep at 400℃ for 5h, finally, cool to 355℃ at a rate of 2℃ / min and keep at 355℃ for 20min; the mechanical assistance is specifically: rotating the furnace body at a speed of 3r / min.

[0047] The infiltrant in the mechanical energy assisted powder zinc infiltration process comprises: zinc powder, indium powder, an activator, ZnCl2 powder, Nb2O5 powder and Al2O3 powder; the mass percentage among them is: 55wt.%, 2wt.%, 4wt.%, 5wt.%, 14wt.%, and the rest is Al2O3 powder. Among them, the activator uses a combination of urea, tetraethylammonium chloride and ethylenediaminetetraacetic acid disodium salt, and the mass ratio among them is 5:2:3.

[0048] Comparative example 5: A method for preparing a multi-element alloyed layer, comprising: Step one, substrate pretreatment: consistent with step one in example 2.

[0049] Step two, plasma spraying: consistent with step two in example 2.

[0050] Step three, zinc infiltration treatment: a mechanical energy assisted powder zinc infiltration process is used to infiltrate zinc on the surface of the multi-element alloy layer prepared in step two, to obtain a multi-element alloyed layer; the parameters of the mechanical energy assisted powder zinc infiltration process are as follows: the zinc infiltration is performed at a pulse temperature, specifically: first, rapidly heat to 355℃ and keep at 355℃ for 29min, then heat to 400℃ at a rate of 7℃ / min and keep at 400℃ for 5h, finally, cool to 355℃ at a rate of 2℃ / min and keep at 355℃ for 20min; the mechanical assistance is specifically: rotating the furnace body at a speed of 3r / min.

[0051] The penetrant in the mechanical energy assisted zinc powder infiltration process comprises zinc powder, indium powder, an activating agent, ZnCl2 powder, B2O3 powder and Al2O3 powder, and the mass percentage of them is 55wt.%, 2wt.%, 4wt.%, 5wt.% and 6wt.%, and the rest is Al2O3 powder. The activating agent is a combination of urea, tetraethylammonium chloride and ethylenediaminetetraacetic acid disodium salt, and the mass ratio of them is 5:2:3.

[0052] Under the same conditions, the polarization curve Tafel parameters and surface hardness of the multielement alloy layer samples prepared in Examples 1-3 and Comparative Examples 1-5 are obtained, and the test results are as follows:

[0053] From the above table, it can be known that the absolute value of the self-corrosion potential of the multielement alloy layer sample prepared in the examples is significantly smaller than that of any one of Comparative Examples 1-5 and the steel substrate, and the corrosion current density is significantly smaller than that of any one of Comparative Examples 1-5 and the steel substrate, indicating that the multielement alloy layer sample prepared in the examples has more excellent corrosion resistance. At the same time, the hardness of the multielement alloy layer sample prepared in the examples is significantly higher than that of any one of Comparative Examples 1-5 and the steel substrate, indicating that the multielement alloy layer sample prepared in the examples has more excellent wear resistance.

Claims

1. A low-temperature preparation method for a highly corrosion-resistant multi-element alloy diffusion layer, characterized in that: include: Step 1: Substrate pretreatment: The steel substrate is subjected to a pretreatment process of surface cleaning and surface roughening in sequence; Step 2: plasma spraying: using a plasma spraying process to prepare a multi-element alloy layer on the surface of the pre-treated steel substrate, and the multi-element alloy layer uses any one of NiCrAlY and NiCoCrAlY metal coatings; Step 3: Sherardizing treatment: using a mechanical energy assisted powder sherardizing process to perform sherardizing on the surface of the multi-component alloy layer prepared in step 2 to obtain a multi-component alloy sherardizing layer.

2. The low-temperature preparation method of a highly corrosion-resistant multi-element alloy diffusion layer according to claim 1, characterized in that: The surface cleaning includes degreasing, deoiling, rust removal and oxide scale removal; degreasing: placing the steel substrate in an organic solvent and cleaning the steel substrate by ultrasonic cleaning. After cleaning, the steel substrate is taken out and its surface is wiped dry. The organic solvent is either acetone or ethanol; rust and oxide scale removal: removing rust and oxide scale from the surface of the steel substrate by mechanical grinding or chemical pickling.

3. A low-temperature preparation method for a highly corrosion-resistant multi-component alloyed layer according to claim 1 or 2, characterized in that: The surface roughening is specifically as follows: first, the surface of the steel substrate is roughened by sandblasting, the sandblasting pressure is 0.4 to 0.7 MPa, and the roughness Ra after sandblasting is 3 to 10 μm; then, the sandblasted steel substrate surface is purged by water-free and oil-free compressed air; then, the steel surface is wiped by an organic solvent such as acetone or ethanol; finally, the steel substrate surface is dried by hot air drying, and the hot air drying temperature is 45 to 50°C.

4. A low-temperature preparation method for a highly corrosion-resistant multi-component alloyed layer according to claim 1 or 3, characterized in that: The plasma spraying process parameters are specifically as follows: spraying power 28-35KW, spraying distance 150-200mm, powder feeding rate 10-50g / min; and multi-element alloy layer thickness 10-20μm.

5. The low-temperature preparation method of a highly corrosion-resistant multi-component alloy diffusion layer according to claim 1 or 3, characterized in that: The parameters of the mechanical energy assisted powder sherardizing process are: sherardizing with pulsed temperature, specifically: first quickly heating to 350-360°C and keeping at 350-360°C for 28-30 minutes, then heating to 395-405°C at a rate of 5-10°C / min and keeping at 395-405°C for 4-6 hours, and finally cooling to 350-360°C at a rate of 1-3°C / min and keeping at 350-360°C for 18-22 minutes; mechanical assistance is specifically: rotating the furnace body and the furnace body speed is 1-5r / min.

6. The low-temperature preparation method of a highly corrosion-resistant multi-component alloy diffusion layer according to claim 1, characterized in that: The penetrants in the mechanical energy assisted powder zinc infiltration process include: zinc powder, indium powder, activator, ZnCl2 powder, B2O3 powder, Nb2O5 powder and Al2O3 powder; the mass percentages of them are: 50~60wt.%, 1~3wt.%, 2~6wt.%, 4~6wt.%, 4~8wt.%, 12~16wt.%, and the rest is Al2O3 powder.

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