Wear-resistant inner pipe of immersion type powder spraying gun and preparation method of wear-resistant inner pipe

Abstract

The invention relates to a wear-resistant inner pipe of an immersion type powder spraying gun and a preparation method thereof, and belongs to the technical field of metallurgy. The preparation method comprises the following steps: S1, processing martensitic stainless steel into an initial circular tube, and carrying out vacuum quenching treatment; s2, soaking the initial round tube in a palladium chloride solution for pretreatment for 30-60 seconds to obtain a pretreated round tube; s3, the pretreated round pipe is vertically inserted into one side groove of a U-shaped deposition groove, the lower end of the round pipe is immersed in deposition liquid for plating treatment for 3-10 h, the deposition liquid is discharged into the other side groove of the U-shaped deposition groove from the upper end of the round pipe in the plating treatment process, and the round pipe containing the Ni-W-P metal plating layer is obtained; and S4, the circular pipe containing the Ni-W-P metal coating is subjected to heat treatment and thinning treatment, and the wear-resistant inner pipe of the immersion type powder spraying gun is obtained. And the wear-resistant inner pipe for the immersion type powder spraying gun, which has erosive wear resistance, thermal shock resistance and high-temperature oxidation resistance, is prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgy, and particularly relates to a wear-resistant inner tube of an immersion powder injection gun and a preparation method thereof. Background Art

[0002] Powder injection metallurgy is a smelting method that uses a carrier gas to inject powdered solid materials into a molten metal, which changes the traditional addition method of metallurgical materials into the furnace in the form of "lumps" and "batch materials". Immersion powder injection means that the outlet of the powder injection gun is located below the molten metal surface, and the powdered materials ejected from the powder injection gun can directly enter the interior of the molten pool without passing through the furnace gas and slag layer.

[0003] On the one hand, immersion powder injection can significantly expand the contact area between solid materials and molten metal, greatly improve the kinetic conditions of the reaction in the molten pool, and accelerate the reaction rate; on the other hand, the powdered solid materials are directly injected into the interior of the molten pool, avoiding contact with air and molten slag, which is beneficial to improving the recovery rate and utilization rate of materials. In addition, immersion powder injection can achieve continuous and controllable batching and feeding, more reasonably control the molten pool temperature and metallurgical reaction, and significantly improve the metallurgical effect.

[0004] The powder injection gun is a key component of the powder injection metallurgy process. The immersion powder injection gun is usually installed on the furnace wall or furnace bottom of a metallurgical furnace, the outlet end is in contact with the high-temperature melt, and is surrounded by high-temperature refractory materials, and the service conditions are very harsh. In order to slow down the high-temperature melting loss of the immersion powder injection gun, a double-layer sleeve structure is usually adopted. The inner tube blows a high-pressure and high-speed powder gas flow, and a cooling protective gas is blown in the annular gap between the inner and outer tubes. In order to strengthen the cooling, the tube walls of the inner and outer tubes are preferably as thin as possible. However, the inner tube of the immersion powder injection gun conveys a high-pressure and high-speed powder gas flow, and the solid powder will inevitably cause serious erosion wear to the inner tube wall. Once the inner tube wall is worn through, the powder injection gun fails and needs to be replaced immediately. In severe cases, it may even lead to a safety accident of high-temperature molten metal leakage. Therefore, the erosion wear resistance of the inner tube of the immersion powder injection gun is very important for its service life. In addition, since metallurgical furnaces generally adopt a periodic operation mode, the immersion powder injection gun frequently undergoes rapid cooling and heating during service, which also puts forward higher requirements for the thermal shock resistance of the immersion powder injection gun. In addition, in a large number of application scenarios, in order to further improve the metallurgical effect of powder injection, the powder injection carrier gas is preferably oxygen, and the inner layer tube of the immersion powder injection gun must have good high-temperature oxidation resistance.

[0005] Coating technologies have been widely applied in many fields. Coating preparation methods include fused spraying, laser cladding, high-velocity oxy-fuel spraying, chemical vapor deposition, electrochemcial deposition, chemical deposition, etc. However, for the inner tube of an immersion powder spray gun, due to its small diameter (usually with an inner diameter less than 30 mm) and long length (usually greater than 500 mm), it is difficult to effectively deposit a coating on the inner wall surface of the immersion powder spray gun inner tube by traditional methods. Moreover, the erosion of the high-speed powder gas flow poses strict requirements on the bonding strength between the coating and the substrate, the internal stress of the coating itself, and the surface quality. Otherwise, it is extremely easy to cause coating peeling or rapid wear.

[0006] Therefore, there is an urgent need for a new method to improve the wear resistance of the inner tube of an immersion powder spray gun. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a wear-resistant inner tube for an immersion powder spray gun and a preparation method thereof. The matrix material and processing technology of the inner tube are optimized. Palladium particles and Ni-W-P metal coatings are deposited on the inner wall surface of the initial circular tube. By combining and adjusting the heat treatment process, the hardness, plastic toughness, internal stress, etc. of the matrix material and the coating are improved synergistically, and a wear-resistant inner tube for an immersion powder spray gun with erosion wear resistance, thermal shock resistance, and high-temperature oxidation resistance is prepared. In addition, based on the performance advantages of the Ni-W-P metal coating, the wall thickness of the inner tube is processed by a stepwise thinning method to improve the cooling effect during the powder spraying service process, and at the same time slow down the burning and wear of the inner tube, thereby extending the service life of the immersion powder spray gun.

[0008] The first object of the present invention is to provide a preparation method for a wear-resistant inner tube of an immersion powder spray gun, including the following steps:

[0009] S1. Process martensitic stainless steel into an initial circular tube and perform vacuum quenching treatment;

[0010] S2. Immerse the initial circular tube in a palladium chloride solution for pretreatment for 30 s - 60 s to obtain a pretreated circular tube;

[0011] S3. Vertically insert the pretreated circular tube into one side groove of a U-shaped deposition tank. The lower end of the circular tube is immersed in the deposition liquid for coating treatment for 3 h - 10 h, and during the coating treatment process, the deposition liquid is drained from the upper end of the circular tube into the other side groove of the U-shaped deposition tank to obtain a circular tube with a Ni-W-P metal coating; the deposition liquid includes the following components: nickel sulfate, sodium tungstate, sodium citrate, sodium hypophosphite, a stabilizer, and a wetting agent;

[0012] S4. Perform heat treatment and thinning treatment on the circular tube with a Ni-W-P metal coating to obtain the wear-resistant inner tube of the immersion powder spray gun.

[0013] In one embodiment of the present invention, in S1, the C content of the martensitic stainless steel is 0.2 wt% - 0.4 wt%, and the Cr content is 12 wt% - 15 wt%. The martensitic stainless steel is a stainless steel with high hardness and wear resistance. Under this condition, the martensitic stainless steel not only has excellent hardness and wear resistance, but also has excellent oxidation resistance.

[0014] In one embodiment of the present invention, in S1, the temperature of the vacuum quenching treatment is 950 °C - 1050 °C, and the time is 30 min - 50 min.

[0015] In one embodiment of the present invention, before S2, it is necessary to polish the inner wall surface of the initial round tube, and wrap the outer wall surface with tape to shield the deposition solution.

[0016] In one embodiment of the present invention, in S2, the concentration of the palladium chloride solution is 1 g / L - 5 g / L; under this condition, nano-scale palladium particles with high uniformity and high density can be formed on the inner wall surface, serving as active sites for the nucleation of the subsequent plating metal, which helps to improve the bonding force between the plating metal and the round tube; at the same time, the size of the palladium particles is appropriate, which helps to increase the deposition rate of the plating metal.

[0017] In one embodiment of the present invention, in S3, during the plating treatment, the height of the round tube immersed in the deposition solution is 50% - 85% of the length of the round tube.

[0018] In one embodiment of the present invention, in S3, during the plating treatment, the maximum flow rate ω of the deposition solution in the round tube satisfies the following relational expression: ω = 2000 × η ÷ ρ ÷ φ 内-1 ; improve the uniformity and compactness of the Ni-W-P metal coating;

[0019] where η is the dynamic viscosity coefficient of the deposition solution, ρ is the density of the deposition solution, and φ 内-1 is the inner diameter of the initial round tube.

[0020] In one embodiment of the present invention, in S3, the concentrations of the components in the deposition solution are: nickel sulfate 18 g / L - 22 g / L, sodium tungstate 24 g / L - 26 g / L, sodium citrate 14 g / L - 16 g / L, sodium hypophosphite 18 g / L - 22 g / L, stabilizer 48 ppm - 52 ppm, and wetting agent 95 ppm - 105 ppm;

[0021] and / or, the stabilizer is selected from thiourea and / or potassium iodide;

[0022] and / or, the wetting agent is selected from one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, and polyethylene glycol-200.

[0023] In one embodiment of the present invention, in S4, the heat treatment is carried out in a protective atmosphere at 350°C - 370°C for 2h - 5h; to eliminate the internal stress of the round tube and the Ni-W-P metal coating, improve its plastic toughness while maintaining a relatively high hardness of the base material, and significantly increase the hardness of the Ni-W-P metal coating.

[0024] In one embodiment of the present invention, in S4, the wall thickness β2 of the round tube in the wear-resistant inner tube of the immersion powder spraying gun satisfies the following relational expression: β2 = β1 - δ - ε × t 上 ;

[0025] wherein, β1 is the wall thickness of the initial round tube, taking 3mm - 6mm; δ is the machining allowance (to prevent serious deformation of the round tube during quenching), taking 0.5mm - 2.5mm; ε is the replacement coefficient, taking 2 - 5; t 上 is the thickness of the Ni-W-P metal coating at the upper end of the round tube after coating treatment, taking 50μm - 200μm.

[0026] The second object of the present invention is to provide a wear-resistant inner tube of an immersion powder spraying gun prepared by the above method. The lower end of the wear-resistant inner tube of the immersion powder spraying gun is used as the inlet end during powder spraying; affected by the powder impact speed and impact angle, the wear rate of the inner tube wall surface is not uniform, and the rapid erosion wear area is located near the inlet end.

[0027] In one embodiment of the present invention, in the wear-resistant inner tube of the immersion powder spraying gun, the W content in the Ni-W-P metal coating is 4wt% - 6wt%, and the P content is 8wt% - 12wt%.

[0028] In one embodiment of the present invention, in the wear-resistant inner tube of the immersion powder spraying gun, the hardness of the Ni-W-P metal coating is 800HV - 1200HV.

[0029] The technical solution of the present invention has the following advantages compared with the prior art:

[0030] (1) The preparation method of the present invention gradually thins the wall thickness of the inner tube, which can not only ensure the structural rigidity during quenching and avoid obvious deformation, but also reduce the machining amount of the high-hardness tube wall after quenching, reduce the processing cost, and fully exert the wear-resistant advantage of the Ni-W-P metal coating, further reducing the total wall thickness of the inner tube, thereby improving the cooling effect during the service of the immersion powder spraying gun and prolonging the service life of the immersion powder spraying gun.

[0031] (2) The preparation method of the present invention can form a Ni-W-P metal coating with good bonding strength, good surface quality and high hardness on the inner wall of the slender round tube.

[0032] (3) In the preparation method of the present invention, by controlling the flow rate of the deposition solution in the circular tube, the deposition solution flows in a laminar flow form in the circular tube, further improving the quality of the Ni-W-P metal coating. The lower end of the circular tube with a better quality and thicker thickness of the Ni-W-P metal coating is used as the inlet end of the inner tube of the powder spray gun to cope with the more rapid erosion and wear at the inlet end.

[0033] (4) The preparation method of the present invention realizes the cooperative heat treatment of the circular tube and the Ni-W-P metal coating, improves its plastic toughness while maintaining the high hardness of the base material, eliminates the internal stress of the Ni-W-P metal coating, and greatly improves the hardness of the metal coating. Specific embodiments

[0034] The following further illustrates the present invention with specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. It should be understood that the specific embodiments are only used to explain the present invention, but the exemplified embodiments do not limit the present invention.

[0035] In the present invention, unless otherwise specified, the technical and scientific terms used in the present invention have the same meanings as those generally understood by those skilled in the technical field to which the present invention belongs.

[0036] In the present invention, unless otherwise specified, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0037] In the present invention, unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods without special instructions, and the materials, reagents, etc. used can be obtained from commercial channels without special instructions.

[0038] In the present invention, unless otherwise specified, the stabilizer used in the embodiments of the present invention is potassium iodide, and the wetting agent is sodium dodecyl sulfate.

[0039] In the present invention, unless otherwise specified, the dynamic viscosity coefficient η and density ρ of the deposition solution involved in the calculation of the maximum flow rate ω in the embodiments of the present invention are approximate numbers. Since the deposition solutions in Example 1 and Example 2 are not very different, the dynamic viscosity coefficient η and density ρ of the two are also not very different.

[0040] Example 1

[0041] The wear-resistant inner tube of the immersion type powder spray gun of the present invention and its preparation method specifically include the following steps:

[0042] S1. Process the martensitic stainless steel with a C content of 0.2 wt% and a Cr content of 13 wt% into a length L1 of 1 m and an outer diameter φ外-1 is 30 mm, with an inner diameter of φ 内-1 is an initial round tube with an inner diameter of 20 mm and a wall thickness β1 of 5 mm, and is subjected to vacuum quenching treatment. It is held at 1000 °C - 1050 °C in a vacuum furnace for 50 min, and then oil-cooled to room temperature;

[0043] S2. Polish the inner wall surface of the initial round tube, wrap the outer wall surface with tape for shielding the deposition solution, and then immerse the whole initial round tube in a palladium chloride solution with a concentration of 3 g / L for 60 s of pretreatment to form uniformly and dispersedly distributed nano-scale palladium particles on the inner wall surface. Take it out and rinse with pure water to obtain a pretreated round tube;

[0044] S3. Vertically insert the pretreated round tube into one side groove of the U-shaped deposition tank. The lower end of the round tube is immersed in the deposition solution, and the height of the round tube immersed in the deposition solution is 80% of the round tube length. The upper end of the round tube is connected to the inlet of the suction pump, and the outlet of the suction pump discharges the deposition solution into the other side groove of the U-shaped deposition tank. Control the flow rate of the deposition solution in the round tube to be 0.025 m / s by adjusting the power of the suction pump (the maximum flow rate ω = 2000×η÷ρ÷φ 内-1 = 2000×0.001÷1000÷0.02 = 0.1 m / s). After 5 h of plating treatment, take it out and rinse with pure water, and remove the tape wrapped on the outer wall surface of the round tube to obtain a round tube with a Ni-W-P metal coating; the concentrations of each component in the deposition solution are: nickel sulfate 20 g / L, sodium tungstate 25 g / L, sodium citrate 15 g / L, sodium hypophosphite 20 g / L, stabilizer 50 ppm, and wetting agent 100 ppm;

[0045] S4. Put the round tube with the Ni-W-P metal coating into a heat treatment furnace, hold it in an argon atmosphere at 370 °C for 4 h, and then take it out and air-cool it to room temperature; measure the thickness t of the Ni-W-P metal coating at the lower end of the round tube 下 is 82 μm, and the thickness t of the Ni-W-P metal coating at the upper end of the round tube 上 is 80 μm. Thin the outer tube wall of the round tube by 1.4 mm according to the thickness of the Ni-W-P metal coating to obtain a wear-resistant inner tube of the immersion type powder gun with a wall thickness β2 of 3.6 mm (β2 = β1 - δ - ε×t 上 = 5 - 1 - 5×0.08 = 3.6 mm); among them, the W content in the Ni-W-P metal coating is 4.8 wt%, the P content is 10.5 wt%, and the rest is Ni; the hardness of the Ni-W-P metal coating is 1080 HV;

[0046] The lower end of the wear-resistant inner tube of the immersion powder spray gun is used as the inlet end, and it is combined with other components to make a powder spray gun. It is installed at the bottom of a 120-ton converter in a steel plant, covered by high-temperature molten steel, and lime powder is sprayed with oxygen as the carrier gas. The bottom blowing of oxygen-lime powder steelmaking is started, and the powder gas flow pressure is set to 1.0 MPa - 1.4 MPa, and the powder flow rate is 150 m / s - 200 m / s. The implementation results show that the erosion rate of the powder spray gun is about 0.51 mm / furnace. After the bottom blowing powder spray gun is used for 1578 furnaces, it stops being used due to erosion to the lower limit; the thinnest position of the inner tube of the powder spray gun is thinned by 0.84 mm.

[0047] Comparative Example 1

[0048] Basically the same as Example 1, the difference is that no pretreatment and coating treatment are carried out, and it specifically includes the following steps:

[0049] S1. Process a martensitic stainless steel with a C content of 0.2 wt% and a Cr content of 13 wt% into an initial round tube with a length L1 of 1 m, an outer diameter φ 外-1 of 30 mm, an inner diameter φ 内-1 of 20 mm, and a wall thickness β1 of 5 mm, and carry out vacuum quenching treatment. Keep it at 1000 °C - 1050 °C in a vacuum furnace for 50 min, and then cool it to room temperature with oil;

[0050] S2. Put the initial round tube into a heat treatment furnace, keep it in an argon atmosphere at 370 °C for 4 h and then take it out and air-cool it to room temperature; thin the outer wall of the round tube by 1 mm to obtain an inner tube with a round tube wall thickness β2 of 4 mm;

[0051] The lower end of the inner tube is used as the inlet end, and it is combined with other components to make a powder spray gun. It is installed at the bottom of a 120-ton converter in a steel plant, covered by high-temperature molten steel, and lime powder is sprayed with oxygen as the carrier gas. The bottom blowing of oxygen-lime powder steelmaking is started, and the powder gas flow pressure is set to 1.0 MPa - 1.4 MPa, and the powder flow rate is 150 m / s - 200 m / s. The implementation results show that the erosion rate of the powder spray gun is about 0.56 mm / furnace. After the bottom blowing powder spray gun is used for 1430 furnaces, it stops being used due to erosion to the lower limit; the thinnest position of the inner tube of the powder spray gun is thinned by 1.15 mm.

[0052] Comparative Example 2

[0053] Basically the same as Example 1, the difference is that no pretreatment is carried out. After heat treatment, the thickness t 下 of the Ni-W-P metal coating at the lower end of the round tube is 71 μm, and the thickness t 上 of the Ni-W-P metal coating at the upper end of the round tube is 67 μm. According to the thickness of the Ni-W-P metal coating, the outer wall of the round tube is thinned by 1.25 mm to obtain an inner tube with a round tube wall thickness β2 of 3.75 mm;

[0054] The lower end of the inner tube is used as the inlet end, and it is combined with other components to make a powder injection lance, which is installed at the bottom of a 120-ton converter in a steel plant and covered by high-temperature molten steel. Lime powder is blown with oxygen as the carrier gas to start bottom-blowing oxygen-lime powder steelmaking. The powder gas flow pressure is set at 1.0 MPa - 1.4 MPa, and the powder flow rate is 150 m / s - 200 m / s. The implementation results show that the erosion rate of the powder injection lance is about 0.52 mm / furnace. After the bottom-blowing powder injection lance is used for 1531 furnaces, it stops being used due to erosion to the lower limit position; the thinnest position of the inner tube of the powder injection lance is reduced by 1.22 mm; and partial peeling of the Ni-W-P metal coating occurs, indicating that the bonding force between the Ni-W-P metal coating and the substrate material is poor.

[0055] Comparative Example 3

[0056] Basically the same as Example 1, except that the heat treatment temperature is adjusted to 420 °C, and the hardness of the Ni-W-P metal coating is 1100 HV;

[0057] The lower end of the inner tube is used as the inlet end, and it is combined with other components to make a powder injection lance, which is installed at the bottom of a 120-ton converter in a steel plant and covered by high-temperature molten steel. Lime powder is blown with oxygen as the carrier gas to start bottom-blowing oxygen-lime powder steelmaking. The powder gas flow pressure is set at 1.0 MPa - 1.4 MPa, and the powder flow rate is 150 m / s - 200 m / s. The implementation results show that the erosion rate of the powder injection lance is about 0.51 mm / furnace. After the bottom-blowing powder injection lance is used for 1570 furnaces, it stops being used due to erosion to the lower limit position; the thinnest position of the inner tube of the powder injection lance is reduced by 0.99 mm, which is significantly greater than that in Example 1. This is because although the increase in the heat treatment temperature slightly increases the hardness of the Ni-W-P metal coating, it also significantly reduces the hardness of the substrate material and improves its plasticity and toughness. The decrease in the hardness of the substrate material reduces its ability to resist powder erosion wear.

[0058] Example 2

[0059] The wear-resistant inner tube of the immersion-type powder injection lance of the present invention and its preparation method specifically include the following steps:

[0060] S1. Process a martensitic stainless steel with a C content of 0.2 wt% and a Cr content of 13 wt% into an initial round tube with a length L1 of 1 m, an outer diameter φ 外-1 of 32 mm, an inner diameter φ 内-1 of 24 mm, and a wall thickness β1 of 4 mm, and perform vacuum quenching treatment. Keep it at 980 °C - 1020 °C in a vacuum furnace for 40 min, and then cool it to room temperature with oil;

[0061] S2. Polish and buff the inner wall surface of the initial round tube. Wrap the outer wall surface with tape to shield the deposition solution. Then, immerse the entire initial round tube in a palladium chloride solution with a concentration of 3 g / L for 60 s of pretreatment to form uniformly and dispersedly distributed nano-scale palladium particles on the inner wall surface. Take it out and rinse with pure water to obtain a pretreated round tube.

[0062] S3. Vertically insert the pretreated round tube into one side slot of the U-shaped deposition tank. Immerse the lower end of the round tube in the deposition solution. The height of the round tube immersed in the deposition solution is 80% of the round tube length. Connect the upper end of the round tube to the inlet of the suction pump. The outlet of the suction pump discharges the deposition solution into the other side slot of the U-shaped deposition tank. Control the flow rate of the deposition solution in the round tube to be 0.03 m / s by adjusting the power of the suction pump (the maximum flow rate ω = 2000×η÷ρ÷φ 内-1 = 2000×0.001÷1000÷0.024 = 0.083 m / s). After 10 h of plating treatment, take it out and rinse with pure water, and remove the tape wrapped on the outer wall surface of the round tube to obtain a round tube with a Ni-W-P metal coating. The concentrations of each component in the deposition solution are: nickel sulfate 20 g / L, sodium tungstate 26 g / L, sodium citrate 15 g / L, sodium hypophosphite 18 g / L, stabilizer 50 ppm, and wetting agent 100 ppm.

[0063] S4. Put the round tube with the Ni-W-P metal coating into a heat treatment furnace, keep it warm for 5 h in an argon atmosphere at 370 °C, and then take it out and air-cool it to room temperature. Measure the thickness t 下 of the Ni-W-P metal coating at the lower end of the round tube to be 158 μm, and the thickness t 上 of the Ni-W-P metal coating at the upper end of the round tube to be 150 μm. Reduce the outer wall of the round tube by 1.6 mm according to the thickness of the Ni-W-P metal coating to obtain a wear-resistant inner tube of the immersion type powder spray gun with a wall thickness β2 of 2.4 mm (β2 = β1 - δ - ε×t 上 = 4 - 1 - 4×0.15 = 2.4 mm). Among them, the W content in the Ni-W-P metal coating is 5.5 wt%, the P content is 9.8 wt%, and the rest is Ni; the hardness of the Ni-W-P metal coating is 1120 HV.

[0064] Use the lower end of the wear-resistant inner tube of the immersion type powder spray gun as the inlet end, combine it with other components to make a powder spray gun, install it at the bottom of a 300-ton converter in a steel plant, cover it with high-temperature molten steel, and blow lime powder with oxygen as the carrier gas to start bottom-blowing oxygen-lime powder steelmaking. Set the powder gas flow pressure to be 1.0 MPa - 1.4 MPa, and the powder flow rate to be 150 m / s - 200 m / s. The implementation results show that the erosion rate of the powder spray gun is about 0.31 mm / furnace. After the bottom-blowing powder spray gun is used for 3225 furnaces, it stops being used due to erosion to the lower limit position; the most severely worn position of the inner tube of the powder spray gun is thinned by 0.98 mm.

[0065] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A method for preparing a wear-resistant inner tube of an immersion powder spraying gun, characterized in that: The following steps are involved: S1, processing martensitic stainless steel into an initial round tube and performing vacuum quenching treatment; S2, immersing the initial round tube in a palladium chloride solution for pretreatment for 30s-60s to obtain a pretreated round tube; S3, vertically inserting the pretreated round tube into one side groove of the U-shaped sedimentation tank, immersing the lower end of the round tube in the sedimentation liquid for coating treatment for 3h-10h, and discharging the sedimentation liquid from the upper end of the round tube into the other side groove of the U-shaped sedimentation tank during the coating treatment, to obtain a round tube containing Ni-WP metal coating; the sedimentation liquid comprises the following components: nickel sulfate, sodium tungstate, sodium citrate, sodium hypophosphite, stabilizer and wetting agent; S4, heat treatment and thinning treatment are performed on the round tube containing the Ni-WP metal coating to obtain the wear-resistant inner tube of the immersion powder spraying gun.

2. The method for preparing the wear-resistant inner tube of the immersion powder spraying gun according to claim 1, characterized in that: In S1, the C content of the martensitic stainless steel is 0.2wt%-0.4wt%, and the Cr content is 12wt%-15wt%.

3. The method for preparing the wear-resistant inner tube of the immersion powder spraying gun according to claim 1, characterized in that: In S1, the temperature of the vacuum quenching treatment is 950°C-1050°C, and the time is 30min-50min.

4. The method for preparing the wear-resistant inner tube of the immersion powder spraying gun according to claim 1, characterized in that: In S2, the concentration of the palladium chloride solution is 1 g / L-5 g / L.

5. The method for preparing the wear-resistant inner tube of the immersion powder spraying gun according to claim 1, characterized in that: In S3, during the coating process, the height of the round tube immersed in the deposition liquid is 50%-85% of the length of the round tube.

6. The method for preparing the wear-resistant inner tube of an immersion powder spraying gun according to claim 1, characterized in that: In S3, during the coating process, the maximum flow rate ω of the deposition liquid in the circular tube satisfies the following relationship: ω=2000×η÷ρ÷φ 内-1 ; Among them, η is the dynamic viscosity coefficient of the sedimentation liquid, ρ is the density of the sedimentation liquid, φ 内-1 is the inner diameter of the initial tube.

7. The method for preparing the wear-resistant inner tube of an immersion powder spraying gun according to claim 1, characterized in that: In S3, the concentrations of the components in the deposition solution are: nickel sulfate 18g / L-22g / L, sodium tungstate 24g / L-26g / L, sodium citrate 14g / L-16g / L, sodium hypophosphite 18g / L-22g / L, stabilizer 48ppm-52ppm and wetting agent 95ppm-105ppm; and / or, the stabilizer is selected from thiourea and / or potassium iodide; And / or, the wetting agent is selected from one or more of sodium lauryl sulfate, sodium lauryl sulfonate and polyethylene glycol-200.

8. The method for preparing the wear-resistant inner tube of an immersion powder spraying gun according to claim 1, characterized in that: In S4, the heat treatment is carried out under a protective atmosphere at 350° C.-370° C. for 2 h-5 h.

9. The method for preparing the wear-resistant inner tube of an immersion powder spraying gun according to claim 1, characterized in that: In S4, the wall thickness β2 of the round tube in the wear-resistant inner tube of the immersion powder spray gun satisfies the following relationship: β2 = β1 - δ - ε × t 上 ; Among them, β1 is the wall thickness of the initial round tube, which is 3mm-6mm; δ is the machining allowance, which is 0.5mm-2.5mm; ε is the replacement coefficient, which is 2-5; t 上 The thickness of the Ni-WP metal coating on the upper end of the round tube after coating treatment is 50 μm-200 μm.

10. The wear-resistant inner tube of an immersion powder spray gun prepared by the method according to any one of claims 1 to 9, characterized in that: The lower end of the wear-resistant inner tube of the immersion powder spraying gun is used as an inlet end during the powder spraying process.