Salt-spray-corrosion-resistant stainless steel rod and preparation method thereof

Abstract

The invention discloses a salt-spray-corrosion-resistant stainless steel rod and a preparation method thereof, and belongs to the technical field of salt-spray-corrosion-resistant stainless steel. The salt-spray-corrosion-resistant stainless steel rod comprises a stainless steel rod body and a corrosion-resistant layer attached to the outer surface of the stainless steel rod body. The method comprises the following steps: sequentially polishing, deoiling, activating and cleaning a stainless steel rod, then putting the stainless steel rod into a chemical composite plating solution for chemical composite plating, then putting the stainless steel rod into a nitric acid solution for chemical etching, introducing hydrogen and hydrocarbon gas in a high-temperature atmosphere, and then continuously heating and introducing composite hydrogen to obtain the salt-spray-corrosion-resistant stainless steel rod, wherein the chemical composite plating solution comprises the following components: 30-40 g / L of nickel sulfate, 15-35 g / L of sodium hypophosphite, 4-6 g / L of citric acid, 32-36 g / L of boric acid, 16-20 g / L of sodium acetate, 0.03-0.05 g / L of carbon black and 20-35 g / L of tungsten carbide particles; the salt-spray-corrosion-resistant stainless steel rod prepared by the invention is relatively good in corrosion resistance, wear resistance and toughness.

Description

Technical Field

[0001] The invention relates to a salt spray corrosion resistant stainless steel rod and a preparation method thereof. Background Art

[0002] As an important metal material, stainless steel bars are widely used in many fields. Due to their excellent comprehensive properties, they are widely used in building structures, machinery manufacturing, marine engineering, chemical equipment, and other scenarios.

[0003] In the construction industry, stainless steel rods are often used to construct railings, handrails, decorative components, etc. They must not only withstand certain external forces but also be exposed to the natural environment for long periods of time. This requires them to have good corrosion resistance and a certain degree of wear resistance to ensure the aesthetic appearance of the building and the safety of the structure. In mechanical manufacturing, stainless steel rods can be used as shafts, rods and other components. They need to maintain stable performance under different working conditions. Corrosion resistance and wear resistance directly affect the service life and operational stability of the machinery. The marine engineering field has even more stringent performance requirements for stainless steel rods. For example, offshore oil platforms and ship structures are exposed to high salt spray and high humidity marine environments for a long time. Stainless steel rods need to have excellent salt spray corrosion resistance. Otherwise, serious corrosion will occur, threatening the safety of the entire project. At the same time, in some actual application scenarios, stainless steel rods are also subject to friction, wear and other effects, and existing austenitic stainless steel rods are difficult to meet the wear resistance requirements of long-term use.

[0004] Therefore, developing a stainless steel rod with good salt spray corrosion resistance and wear resistance and a preparation method thereof has important practical significance. Summary of the Invention

[0005] The purpose of the present invention is to provide a salt spray corrosion resistant stainless steel rod and a preparation method thereof, so as to solve the technical problems mentioned in the above background technology.

[0006] The technical solution for achieving the purpose of the present invention is: In a first aspect, the present invention provides a salt spray corrosion resistant stainless steel rod, comprising a stainless steel rod and a corrosion resistant layer attached to the outer surface of the stainless steel rod; the salt spray corrosion resistant stainless steel rod is obtained by placing a pretreated stainless steel rod into a chemical composite plating solution for chemical composite plating, then placing the pretreated stainless steel rod into a nitric acid solution for chemical etching, introducing hydrogen and hydrocarbon gases in a high temperature atmosphere, and then continuing to increase the temperature to introduce composite hydrogen to obtain the salt spray corrosion resistant stainless steel rod.

[0007] Furthermore, the pretreated stainless steel rod is obtained by sequentially subjecting the stainless steel rod to grinding, degreasing, activation, and cleaning.

[0008] Furthermore, the formula of the chemical composite plating solution is as follows: 30-40 g / L nickel sulfate, 15-35 g / L sodium hypophosphite, 4-6 g / L citric acid, 32-36 g / L boric acid, 16-20 g / L sodium acetate, 0.03-0.05 g / L carbon black, and 20-35 g / L tungsten carbide particles.

[0009] Furthermore, the composite hydrogen is hydrogen carrying silicon tetrachloride.

[0010] In a second aspect, the present invention provides a method for preparing the salt spray corrosion resistant stainless steel rod as described in the first aspect, comprising the steps of: (1) Grind, degrease, activate and clean the stainless steel rods in sequence; (2) Place the stainless steel rod treated in step (1) into a chemical composite plating solution for chemical composite plating. The conditions for chemical composite plating are as follows: pH 2-4, temperature 80-90°C, time 2-4 hours, and stirring method is ultrasonic vibration; (3) placing the stainless steel rod treated in step (2) in a nitric acid solution for chemical etching; (4) The stainless steel rod treated in step (3) is placed in a tube furnace, the quartz tube is first evacuated with nitrogen, and then the temperature is raised to 500-700°C under nitrogen conditions, and hydrogen is introduced and kept warm for 9-11 minutes, followed by introduction of acetylene and keeping warm for 15-25 minutes, and then nitrogen is introduced to evacuate the quartz tube, and then the temperature is raised to 1200±10°C under nitrogen conditions and kept warm for 10 minutes, and then hydrogen loaded with silicon tetrachloride is introduced and kept warm for 30-50 minutes, and then cooled to room temperature under nitrogen atmosphere to obtain a salt spray corrosion resistant stainless steel rod.

[0011] Furthermore, the degreasing liquid used for the degreasing is formulated as follows: 38-42 g / L of sodium hydroxide, 28-32 g / L of sodium carbonate, and 38-42 g / L of sodium phosphate.

[0012] Furthermore, the nitric acid solution is an 8 mol / L nitric acid solution; the temperature of the chemical etching is 38-42° C., and the time is 45-55 s.

[0013] Furthermore, the flow rate of hydrogen is 80~320mL / min, the flow rate of nitrogen is 100~200mL / min, the flow rate of acetylene is 70~90mL / min, and the flow rate of hydrogen carrying silicon tetrachloride is 40~80mL / min.

[0014] Furthermore, the flow ratio of hydrogen to silicon tetrachloride in the hydrogen carrying silicon tetrachloride is 2.5-3.5:1.

[0015] Furthermore, the heating rate of step (4) is 2-5°C / min.

[0016] By adopting the above technical solution, the present invention has the following beneficial effects: (1) The salt spray corrosion resistant stainless steel rod of the present invention comprises a stainless steel rod and a corrosion resistant layer attached to the outer surface of the stainless steel rod; specifically, the pretreated stainless steel rod is first placed in a chemical composite plating solution for chemical composite plating, then placed in a nitric acid solution for chemical etching, hydrogen and hydrocarbon gases are introduced under a high temperature atmosphere, and then the temperature is continued to be raised to introduce composite hydrogen, thereby obtaining a stainless steel rod that is resistant to salt spray corrosion and has good wear resistance.

[0017] (2) The pretreated stainless steel rod of the present invention is obtained by sequentially grinding, degreasing, activating and cleaning the stainless steel rod. Before chemical composite plating, the stainless steel rod is sequentially subjected to grinding, degreasing, activation and cleaning pretreatment. The oxide layer, burrs and roughness on the surface of the stainless steel rod are eliminated by grinding. The stainless steel rod is polished until the mirror surface is glossy and has fewer scratches, thereby providing a uniform base for subsequent processing of the stainless steel rod. The degreasing is used to remove organic contamination such as grease and cutting fluid to ensure that the surface of the stainless steel rod is clean. The activation is used to remove the passivation film on the surface of the stainless steel rod to expose the active surface of the stainless steel rod to enhance the adhesion of the coating, thereby ensuring that the surface of the stainless steel rod meets the activity and cleanliness requirements required for chemical composite plating, thereby ensuring the bonding strength and corrosion resistance of the coating.

[0018] (3) The chemical composite plating solution of the present invention is formulated as follows: 30-40 g / L nickel sulfate, 15-35 g / L sodium hypophosphite, 4-6 g / L citric acid, 32-36 g / L boric acid, 16-20 g / L sodium acetate, 0.03-0.05 g / L carbon black, and 20-35 g / L tungsten carbide particles. The chemical composite plating solution with the above formula is used to chemically composite plate a stainless steel rod, thereby forming a nickel-phosphorus-tungsten carbide coating on the outside of the stainless steel rod. The chemically plated nickel-phosphorus coating has excellent wear resistance, corrosion resistance, hardness, and weldability. The microstructure of the nickel-phosphorus coating depends on the phosphorus content: low phosphorus (1-5 wt%) forms a crystalline structure, medium phosphorus (6-9 wt%) produces a mixed amorphous-crystalline structure, and high phosphorus (10-13 wt%) produces a mixed amorphous-crystalline structure. wt%) results in a completely amorphous structure; with the increase of phosphorus content, corrosion resistance improves, while the increase in hardness is related to the typical crystal structure at low phosphorus content. Generally speaking, when the phosphorus content in the coating increases to more than 8% (mass fraction), the corrosion resistance will be significantly improved; and as the phosphorus content in the coating decreases to below 8%, the wear resistance will be improved; in order to make the prepared nickel-phosphorus coating have good wear resistance, corrosion resistance and hardness at the same time, hard second phase tungsten carbide particles are introduced into the chemical nickel-phosphorus coating. The inert tungsten carbide particles are transferred from the main solution to the substrate by forced convection. They are loosely adsorbed on the surface of the substrate and are irreversibly incorporated into the growing nickel-phosphorus matrix. The hardness and tribological properties of the coating are improved by dispersing and hindering the rapid propagation of dislocations in the ductile nickel matrix.

[0019] (4) After the chemical composite plating of the present invention, the coating is placed in a nitric acid solution for chemical etching. There is a large electrochemical potential difference between the nano carbon black particles and the nickel-phosphorus matrix. The micro-areas where these nano etching points are located are preferentially etched, forming a directional etching centered on the nano etching points, so that the surface of the nanoporous nickel-phosphorus coating presents a rich micro-nanopore structure, and the specific surface area of the coating is also greatly increased. Subsequently, when hydrogen and hydrocarbon gases are introduced into the high temperature atmosphere, a large number of carbon nanofibers with a spiral structure are grown in situ in the nickel-phosphorus coating with the nanoporous nickel-phosphorus coating as a catalytic template and acetylene as a carbon source. The carbon nanofibers with a spiral structure can absorb impact energy through elastic deformation, and their three-dimensional spiral shape can effectively deflect the crack path and slow down the crack propagation speed, thereby increasing the impact resistance of the coating on the surface of the stainless steel rod. Then, the temperature is increased and composite hydrogen is introduced. The composite hydrogen is hydrogen carrying silicon tetrachloride. The silicon reaction is introduced to form spiral silicon carbide and silicon carbide on the surface of the nickel-phosphorus matrix, further enhancing the corrosion resistance and wear resistance of the salt spray corrosion resistant stainless steel rod. DETAILED DESCRIPTION

[0020] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with specific implementation methods.

[0021] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0022] The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0023] In the embodiment of the present invention and the comparative example, the tungsten carbide used was tungsten carbide with a particle size of 400 nm, the carbon black used was carbon black with a particle size of 50 nm; and the stainless steel rod used was 304 stainless steel rod with a diameter of 50 mm.

[0024] (Example 1) A method for preparing a salt spray corrosion resistant stainless steel rod, comprising the following steps: (1) Use 200#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper to polish the stainless steel rod step by step until the mirror surface appears glossy and has fewer scratches; degrease the polished stainless steel rod with degreasing liquid at 85°C for 15 minutes; activate the degreased stainless steel rod with 10% hydrochloric acid for 5 minutes, and then rinse it with pure water 5 times; (2) placing the stainless steel rod treated in step (1) into a chemical composite plating solution for chemical composite plating. The conditions for chemical composite plating are as follows: pH 2, temperature 80°C, time 2 hours, and stirring mode ultrasonic vibration; (3) placing the stainless steel rod treated in step (2) in an 8 mol / L nitric acid solution and chemically etching it at 38°C for 45 seconds; (4) The stainless steel rod treated in step (3) is placed in a tube furnace, the quartz tube is first evacuated with nitrogen, and then the temperature is raised to 500°C at 2°C / min under nitrogen, and hydrogen is introduced for 25 minutes after being kept warm for 9 minutes, and then acetylene is introduced for 15 minutes, and then nitrogen is introduced to evacuate the quartz tube, and then the temperature is raised to 1190°C at 2°C / min under nitrogen, and hydrogen carrying silicon tetrachloride is introduced for 30 minutes after being kept warm, and the tube is cooled to room temperature under nitrogen atmosphere to obtain a salt spray corrosion resistant stainless steel rod; wherein the flow rate of hydrogen is 80 mL / min, the flow rate of nitrogen is 100 mL / min, the flow rate of acetylene is 70 mL / min, and the flow rate of hydrogen carrying silicon tetrachloride is 40 mL / min; the flow ratio of hydrogen to silicon tetrachloride in the hydrogen carrying silicon tetrachloride is 2.5:1.

[0025] The formula of the degreasing liquid is: 38g / L sodium hydroxide, 28g / L sodium carbonate, and 38g / L sodium phosphate.

[0026] The formula of the chemical composite plating solution is as follows: nickel sulfate 30g / L, sodium hypophosphite 15g / L, citric acid 4g / L, boric acid 32g / L, sodium acetate 16g / L, carbon black 0.03g / L, and tungsten carbide particles 20g / L.

[0027] The thickness of the corrosion-resistant layer of the salt spray corrosion-resistant stainless steel rod is 103 μm.

[0028] (Example 2) A method for preparing a salt spray corrosion resistant stainless steel rod, comprising the following steps: (1) Use 200#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper to polish the stainless steel rod step by step until the mirror surface appears glossy and has fewer scratches; degrease the polished stainless steel rod with degreasing liquid at 85°C for 15 minutes; activate the degreased stainless steel rod with 10% hydrochloric acid for 5 minutes, and then rinse it with pure water 5 times; (2) placing the stainless steel rod treated in step (1) into a chemical composite plating solution for chemical composite plating. The conditions for chemical composite plating are as follows: pH 3, temperature 85°C, time 3 hours, and stirring mode ultrasonic vibration; (3) placing the stainless steel rod treated in step (2) in an 8 mol / L nitric acid solution and chemically etching it at 40°C for 50 seconds; (4) The stainless steel rod treated in step (3) is placed in a tube furnace, the quartz tube is first evacuated with nitrogen, and then the temperature is raised to 600°C at 5°C / min under nitrogen, and after keeping the temperature for 10 minutes, hydrogen is introduced and kept warm for 30 minutes, followed by acetylene and kept warm for 20 minutes, and then nitrogen is introduced to evacuate the quartz tube, and then the temperature is raised to 1200°C at 5°C / min under nitrogen, and after keeping the temperature for 10 minutes, hydrogen carrying silicon tetrachloride is introduced and kept warm for 40 minutes, and the mixture is cooled to room temperature under nitrogen atmosphere to obtain a salt spray corrosion resistant stainless steel rod; wherein the flow rate of hydrogen is 200 mL / min, the flow rate of nitrogen is 150 mL / min, the flow rate of acetylene is 80 mL / min, and the flow rate of hydrogen carrying silicon tetrachloride is 60 mL / min; the flow ratio of hydrogen to silicon tetrachloride in the hydrogen carrying silicon tetrachloride is 3:1.

[0029] The formula of the degreasing liquid is: 40g / L sodium hydroxide, 30g / L sodium carbonate, and 40g / L sodium phosphate.

[0030] The formula of the chemical composite plating solution is as follows: nickel sulfate 35g / L, sodium hypophosphite 25g / L, citric acid 5g / L, boric acid 34g / L, sodium acetate 18g / L, carbon black 0.04g / L, and tungsten carbide particles 28g / L.

[0031] The corrosion-resistant layer thickness of the salt spray corrosion-resistant stainless steel rod is 103 μm.

[0032] (Example 3) A method for preparing a salt spray corrosion resistant stainless steel rod, comprising the following steps: (1) Use 200#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper to polish the stainless steel rod step by step until the mirror surface appears glossy and has fewer scratches; degrease the polished stainless steel rod with degreasing liquid at 85°C for 15 minutes; activate the degreased stainless steel rod with 10% hydrochloric acid for 5 minutes, and then rinse it with pure water 5 times; (2) placing the stainless steel rod treated in step (1) into a chemical composite plating solution for chemical composite plating, wherein the conditions for chemical composite plating are as follows: pH 4, temperature 90°C, time 4 hours, and stirring mode ultrasonic vibration; (3) placing the stainless steel rod treated in step (2) in an 8 mol / L nitric acid solution and chemically etching it at 42°C for 55 seconds; (4) The stainless steel rod treated in step (3) is placed in a tube furnace, the quartz tube is first evacuated with nitrogen, and then the temperature is raised to 700°C at 5°C / min under nitrogen, and after being kept warm for 11 minutes, hydrogen is introduced and kept warm for 35 minutes, followed by acetylene and kept warm for 25 minutes, and then nitrogen is introduced to evacuate the quartz tube, and then the temperature is raised to 1210°C at 5°C / min under nitrogen, and after being kept warm for 10 minutes, hydrogen carrying silicon tetrachloride is introduced and kept warm for 50 minutes, and the mixture is cooled to room temperature under nitrogen atmosphere to obtain a salt spray corrosion resistant stainless steel rod; wherein the flow rate of hydrogen is 320 mL / min, the flow rate of nitrogen is 200 mL / min, the flow rate of acetylene is 90 mL / min, and the flow rate of hydrogen carrying silicon tetrachloride is 80 mL / min; and the flow ratio of hydrogen to silicon tetrachloride in the hydrogen carrying silicon tetrachloride is 3.5:1.

[0033] The formula of the degreasing liquid is: sodium hydroxide 42g / L, sodium carbonate 32g / L, and sodium phosphate 42g / L.

[0034] The formula of the chemical composite plating solution is as follows: nickel sulfate 40g / L, sodium hypophosphite 35g / L, citric acid 6g / L, boric acid 36g / L, sodium acetate 20g / L, carbon black 0.05g / L, and tungsten carbide particles 35g / L.

[0035] The corrosion-resistant layer thickness of the salt spray corrosion-resistant stainless steel rod is 103 μm.

[0036] (Comparative Example 1) A method for preparing a salt spray corrosion resistant stainless steel rod, comprising the following steps: (1) Use 200#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper to polish the stainless steel rod step by step until the mirror surface appears glossy and has fewer scratches; degrease the polished stainless steel rod with degreasing liquid at 85°C for 15 minutes; activate the degreased stainless steel rod with 10% hydrochloric acid for 5 minutes, and then rinse it with pure water 5 times; (2) placing the stainless steel rod treated in step (1) into a chemical composite plating solution for chemical composite plating. The conditions for chemical composite plating are as follows: pH 3, temperature 85°C, time 3 hours, and stirring mode ultrasonic vibration; (3) placing the stainless steel rod treated in step (2) in an 8 mol / L nitric acid solution and chemically etching it at 40°C for 50 seconds; (4) The stainless steel rod treated in step (3) is placed in a tube furnace, the quartz tube is first evacuated with nitrogen, and then the temperature is raised to 600°C at 5°C / min under nitrogen, and after keeping the temperature for 10 minutes, hydrogen is introduced and kept warm for 30 minutes, followed by acetylene and kept warm for 20 minutes, and then nitrogen is introduced to evacuate the quartz tube, and then the temperature is raised to 1200°C at 5°C / min under nitrogen, and after keeping the temperature for 10 minutes, hydrogen carrying silicon tetrachloride is introduced and kept warm for 40 minutes, and the mixture is cooled to room temperature under nitrogen atmosphere to obtain a salt spray corrosion resistant stainless steel rod; wherein the flow rate of hydrogen is 200 mL / min, the flow rate of nitrogen is 150 mL / min, the flow rate of acetylene is 80 mL / min, and the flow rate of hydrogen carrying silicon tetrachloride is 60 mL / min; the flow ratio of hydrogen to silicon tetrachloride in the hydrogen carrying silicon tetrachloride is 3:1.

[0037] The formula of the degreasing liquid is: 40g / L sodium hydroxide, 30g / L sodium carbonate, and 40g / L sodium phosphate.

[0038] The formula of the chemical composite plating solution is as follows: nickel sulfate 35 g / L, sodium hypophosphite 25 g / L, citric acid 5 g / L, boric acid 34 g / L, sodium acetate 18 g / L, and carbon black 0.04 g / L.

[0039] The corrosion-resistant layer thickness of the salt spray corrosion-resistant stainless steel rod is 103 μm.

[0040] (Comparative Example 2) A method for preparing a salt spray corrosion resistant stainless steel rod, comprising the following steps: (1) Use 200#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper to polish the stainless steel rod step by step until the mirror surface appears glossy and has fewer scratches; degrease the polished stainless steel rod with degreasing liquid at 85°C for 15 minutes; activate the degreased stainless steel rod with 10% hydrochloric acid for 5 minutes, and then rinse it with pure water 5 times; (2) placing the stainless steel rod treated in step (1) into a chemical composite plating solution for chemical composite plating. The conditions for chemical composite plating are as follows: pH 3, temperature 85°C, time 3 hours, and stirring mode ultrasonic vibration; (3) placing the stainless steel rod treated in step (2) in an 8 mol / L nitric acid solution and chemically etching it at 40°C for 50 seconds; (4) The stainless steel rod treated in step (3) is placed in a tubular furnace, the quartz tube is first evacuated with nitrogen, and then the temperature is raised to 1200°C at 5°C / min under nitrogen conditions and kept warm for 10 minutes, and then hydrogen carrying silicon tetrachloride is introduced and kept warm for 40 minutes, and then cooled to room temperature under nitrogen atmosphere to obtain a salt spray corrosion resistant stainless steel rod; wherein the flow rate of hydrogen carrying silicon tetrachloride is 60 mL / min; and the flow ratio of hydrogen to silicon tetrachloride in the hydrogen carrying silicon tetrachloride is 3:1.

[0041] The formula of the degreasing liquid is: 40g / L sodium hydroxide, 30g / L sodium carbonate, and 40g / L sodium phosphate.

[0042] The formula of the chemical composite plating solution is as follows: nickel sulfate 35g / L, sodium hypophosphite 25g / L, citric acid 5g / L, boric acid 34g / L, sodium acetate 18g / L, carbon black 0.04g / L, and tungsten carbide particles 28g / L.

[0043] The corrosion-resistant layer thickness of the salt spray corrosion-resistant stainless steel rod is 103 μm.

[0044] (Comparative Example 3) A method for preparing a salt spray corrosion resistant stainless steel rod, comprising the following steps: (1) Use 200#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper to polish the stainless steel rod step by step until the mirror surface appears glossy and has fewer scratches; degrease the polished stainless steel rod with degreasing liquid at 85°C for 15 minutes; activate the degreased stainless steel rod with 10% hydrochloric acid for 5 minutes, and then rinse it with pure water 5 times; (2) placing the stainless steel rod treated in step (1) into a chemical composite plating solution for chemical composite plating. The conditions for chemical composite plating are as follows: pH 3, temperature 85°C, time 3 hours, and stirring mode ultrasonic vibration; (3) placing the stainless steel rod treated in step (2) in an 8 mol / L nitric acid solution and chemically etching it at 40°C for 50 seconds; (4) The stainless steel rod treated in step (3) was placed in a tubular furnace. The quartz tube was first evacuated with nitrogen. Then, under nitrogen conditions, the temperature was raised to 600°C at a rate of 5°C / min. After keeping the temperature for 10 minutes, hydrogen was introduced and kept warm for 30 minutes. Then, acetylene was introduced and kept warm for 20 minutes. The flow rate of hydrogen was 200 mL / min, the flow rate of nitrogen was 150 mL / min, and the flow rate of acetylene was 80 mL / min.

[0045] The formula of the degreasing liquid is: 40g / L sodium hydroxide, 30g / L sodium carbonate, and 40g / L sodium phosphate.

[0046] The formula of the chemical composite plating solution is as follows: nickel sulfate 35g / L, sodium hypophosphite 25g / L, citric acid 5g / L, boric acid 34g / L, sodium acetate 18g / L, carbon black 0.04g / L, and tungsten carbide particles 28g / L.

[0047] The corrosion-resistant layer thickness of the salt spray corrosion-resistant stainless steel rod is 103 μm.

[0048] (Effect example) Table 1 below shows the performance test results of the salt spray corrosion resistant stainless steel rods prepared in Examples and Comparative Examples: Table 1

[0049] From the data in Table 1, it can be seen that the salt spray corrosion resistant stainless steel bars prepared in Examples 1 to 3 have good salt spray corrosion resistance, wear resistance, hardness and impact resistance; The difference between Comparative Example 1 and Example 2 is that no tungsten carbide particles are added to the chemical composite plating solution, and the hardness and wear resistance of the obtained salt spray corrosion-resistant stainless steel rod are poor.

[0050] The difference between Comparative Example 2 and Example 2 is that hydrogen and hydrocarbon gases are not introduced in a high-temperature atmosphere after chemical composite plating and chemical etching, and a silicon base layer is formed on the surface of the coating. The impact resistance, hardness and wear resistance of the salt spray corrosion-resistant stainless steel rod obtained are poor.

[0051] The difference between Comparative Example 3 and Example 2 is that after chemical composite plating, chemical etching, and the introduction of hydrogen and hydrocarbon gases in a high-temperature atmosphere, the temperature is not further increased to introduce composite hydrogen. The salt spray corrosion resistance, wear resistance, and hardness of the obtained salt spray corrosion-resistant stainless steel rod are poor. Due to the introduction of carbon black and carbon fiber and the absence of the formation of silicon carbide and silicon layers, the salt spray corrosion resistance of the salt spray corrosion-resistant stainless steel rod is worse than the corrosion resistance of the conventional nickel-phosphorus coating for 120 hours in Comparative Example 3.

[0052] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A salt spray corrosion resistant stainless steel rod, comprising a stainless steel rod and a corrosion resistant layer attached to the outer surface of the stainless steel rod; characterized in that: The salt spray corrosion resistant stainless steel rod is prepared by placing a pretreated stainless steel rod into a chemical composite plating solution for chemical composite plating, then placing the pretreated stainless steel rod into a nitric acid solution for chemical etching, introducing hydrogen and hydrocarbon gas in a high temperature atmosphere, and then continuing to increase the temperature to introduce composite hydrogen to obtain the salt spray corrosion resistant stainless steel rod.

2. The salt spray corrosion resistant stainless steel rod according to claim 1, characterized in that: The pretreated stainless steel rod is obtained by sequentially subjecting the stainless steel rod to grinding, degreasing, activation and cleaning.

3. The salt spray corrosion resistant stainless steel rod according to claim 1, characterized in that: The formula of the chemical composite plating solution is as follows: 30-40 g / L nickel sulfate, 15-35 g / L sodium hypophosphite, 4-6 g / L citric acid, 32-36 g / L boric acid, 16-20 g / L sodium acetate, 0.03-0.05 g / L carbon black, and 20-35 g / L tungsten carbide particles.

4. The salt spray corrosion resistant stainless steel rod according to claim 1, characterized in that: The composite hydrogen is hydrogen carrying silicon tetrachloride.

5. A method for preparing a salt spray corrosion resistant stainless steel rod according to any one of claims 1 to 4, characterized in that the steps include: (1) Grind, degrease, activate and clean the stainless steel rods in sequence; (2) placing the stainless steel rod treated in step (1) into a chemical composite plating solution for chemical composite plating; the conditions for chemical composite plating are as follows: pH 2-4, temperature 80-90°C, time 2-4h, and stirring mode ultrasonic vibration; (3) placing the stainless steel rod treated in step (2) in a nitric acid solution for chemical etching; (4) The stainless steel rod treated in step (3) is placed in a tube furnace, the quartz tube is first evacuated with nitrogen, and then the temperature is raised to 500-700°C under nitrogen conditions, and hydrogen is introduced and kept warm for 9-11 minutes, followed by introduction of acetylene and keeping warm for 15-25 minutes, and then nitrogen is introduced to evacuate the quartz tube, and then the temperature is raised to 1200±10°C under nitrogen conditions and kept warm for 10 minutes, and then hydrogen loaded with silicon tetrachloride is introduced and kept warm for 30-50 minutes, and then cooled to room temperature under nitrogen atmosphere to obtain a salt spray corrosion resistant stainless steel rod.

6. The salt spray corrosion resistant stainless steel rod according to claim 5, characterized in that: The degreasing liquid used in the degreasing is formulated as follows: 38-42 g / L of sodium hydroxide, 28-32 g / L of sodium carbonate, and 38-42 g / L of sodium phosphate.

7. The salt spray corrosion resistant stainless steel rod according to claim 5, characterized in that: The nitric acid solution is 8 mol / L nitric acid solution; the temperature of the chemical etching is 38-42° C., and the time is 45-55 s.

8. The salt spray corrosion resistant stainless steel rod according to claim 5, characterized in that: The flow rate of the hydrogen is 80-320 mL / min, the flow rate of the nitrogen is 100-200 mL / min, the flow rate of the acetylene is 70-90 mL / min, and the flow rate of the hydrogen carrying silicon tetrachloride is 40-80 mL / min.

9. The salt spray corrosion resistant stainless steel rod according to claim 8, characterized in that: The flow ratio of hydrogen to silicon tetrachloride in the hydrogen carrying silicon tetrachloride is 2.5-3.5:

1.

10. The salt spray corrosion resistant stainless steel rod according to claim 5, characterized in that: The heating rate of step (4) is 2-5°C / min.

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