CN109128542B - Method for compositely welding stainless steel seawater filter element by laser spot welding and vacuum brazing - Google Patents
Method for compositely welding stainless steel seawater filter element by laser spot welding and vacuum brazing Download PDFInfo
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- CN109128542B CN109128542B CN201811170281.XA CN201811170281A CN109128542B CN 109128542 B CN109128542 B CN 109128542B CN 201811170281 A CN201811170281 A CN 201811170281A CN 109128542 B CN109128542 B CN 109128542B
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K28/00—Welding or cutting not covered by any of the preceding groups, e.g. electrolytic welding
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Abstract
A method for welding a stainless steel seawater filter element by combining laser spot welding and vacuum brazing includes the steps of firstly, conducting surface pretreatment on to-be-welded parts of an inner framework and a filter screen of the stainless steel seawater filter element, then fixing the to-be-welded parts by a clamp, secondly, conducting spot welding fixing on the to-be-welded parts on the surface of the inner framework according to the number of turns of the filter screen by adopting laser spot welding, then coating brazing filler metal paste in the to-be-welded surfaces, and finally conducting brazing on the to-be-welded positions except the laser spot welding position by adopting vacuum brazing, so that welding of the stainless steel seawater filter element is completed. According to the invention, due to the low temperature during the laser spot welding-vacuum brazing composite welding of the connecting steel, the generation of nitrides, carbides and carbonitrides at the joint can be effectively prevented to reduce the performance of the connecting steel, the problem of structural property change is avoided, and the welded joint has the advantages of no defect, high cleanliness and excellent performance.
Description
Technical Field
The invention relates to a stainless steel seawater filter element in the field of seawater purification, in particular to a method for welding a stainless steel seawater filter element by combining laser spot welding and vacuum brazing.
Background
The seawater filter element is used as an important component of seawater purification equipment and comprises an inner framework, a filter layer protecting net, a filter screen, an outer protecting net and the like, and the main connection methods comprise fusion welding, surfacing welding, thermal sintering and the like.
In the prior art, the stainless steel seawater filter element is mainly used for manual arc welding at present, but because the filter screen and the inner framework have more welding points and small connecting points, the defects of no welding or no penetration, erosion, welding penetration and the like easily occur, the welding efficiency is particularly low, and a large amount of welding materials are needed.
Disclosure of Invention
In order to solve the problems of infirm welding, corrosion, low welding efficiency and the like of welding a stainless steel seawater filter element by adopting manual electric arc welding in the prior art, the invention provides the composite welding method for the stainless steel seawater filter element.
The technical scheme adopted by the invention for solving the technical problems is as follows: the utility model provides a method of laser spot welding and vacuum brazing hybrid welding stainless steel sea water filter core, treat that the welding position carries out surface preparation at first to the inner frame and the filter screen of stainless steel sea water filter core, then treat the welding position with the anchor clamps is fixed, secondly, adopt laser spot welding to treat that the welding position carries out spot welding according to the filter screen number of turns on the inner frame surface and fixes, later coat in treating the face with solder paste, adopt vacuum brazing to treat the welding position to all the other welding positions except laser spot welding position again at last to accomplish the welding of stainless steel sea water filter core, the operation of vacuum brazing is as follows: 1) assembling the fixed surface to be welded by laser spot welding by using a clamp, coating prefabricated solder paste, and then putting the whole workpiece into a vacuum cavity; 2) the vacuum degree of the vacuum chamber was set to 10-6～10-4Pa; 3) setting a temperature control unit, heating to 1047-1239 ℃ to melt the brazing filler metal paste, and keeping the temperature for 45-55 s; 4) and after the heat preservation is finished, naturally cooling, opening the vacuum cavity air inlet unit when the workpiece to be welded is cooled to room temperature, opening the vacuum cavity unit when the pressure inside and outside the cavity is the same, and taking out the workpiece to finish the welding of the stainless steel seawater filter element.
In the present invention, the laser spot welding is specifically performed as follows:
1) fixing the inner skeleton and the filter screen to be welded by using a clamp, and then setting the laser spot welding process parameters as follows: the laser power is 400-500W, the spot welding time is 120-180 ms, the welding speed is 5-8 mm/s, the focal length of the lens is phi 50 multiplied by 100-phi 50 multiplied by 120mm, and the light emitting frequency is 10-15 HZ;
2) and performing laser spot welding according to the laser spot welding process parameters, enabling the laser power to be increased from 0 to 100% of full power within 0.5ms initially, then continuing for 8.5-9 ms at 100% of full power, completing the laser spot welding within the continuous time, and then rapidly reducing the laser power from 100% of full power to 0 within 0.4 ms.
In the invention, the surface pretreatment comprises mechanical polishing, electrolytic polishing solution preparation and electrolytic polishing in sequence, and the specific operations are as follows:
1) mechanical polishing
The surface of a workpiece to be welded is polished, and the workpiece to be welded is mechanically polished by dry and wet metallographic abrasive paper of 100#, 400#, 600#, 800#, 1000#, 1500# and 2000# in sequence, and then mechanically polished by a gold velvet polishing cloth matched with M1.5 polishing agent;
2) preparing electrolytic polishing solution
Mixing perchloric acid and ethanol according to the volume fraction of 1:4 to obtain an electrolytic polishing solution; the electrolytic polishing solution needs to be prepared 24 hours in advance, and the standing time is not too long, generally not longer than 14 days;
3) electrolytic polishing
Carrying out electrolytic polishing on the workpiece mechanically polished in the step 1) by using the electrolytic polishing solution prepared in the step 2), wherein the electrolytic polishing direct current voltage is 15-20V, the current is 1.0-1.5A, the temperature is-20 ℃ to-30 ℃, and the polishing time is 40-75 s;
4) and after the electrolytic polishing is finished, cleaning the workpiece by using ethanol to remove the acid solution on the surface of the workpiece, thus finishing the surface pretreatment.
The brazing paste used by the invention preferably comprises the following components, by weight, 25-28 parts of Pd, 2.8-5.8 parts of vanadium-plated graphene, 39-46 parts of Ni, 36-39 parts of Cr, 12-15 parts of Mn, 7-11 parts of Re, 6-9 parts of Si and 2-5.5 parts of B.
The preparation method of the solder paste comprises the following steps:
1) weighing the components according to the proportion, and ball-milling the components to powder with the particle size of 128 microns for later use;
2) formulating water-based binders
Weighing 36 parts of zinc phosphate, 45 parts of ammonium chloride, 15 parts of polyethylene glycol and 14 parts of butyl cyanoacrylate according to the weight ratio, and uniformly mixing to prepare a water-based binder for later use;
3) weighing 70 parts of the powder prepared in the step 1), 15 parts of distilled water, 15 parts of the water-based binder prepared in the step 2) and 5 parts of acetone according to the weight ratio for later use;
4) mixing the distilled water, the water-based binder and the acetone weighed in the step 3), uniformly stirring until no precipitate is generated, then adding the weighed powder into the mixture, uniformly stirring, and keeping the vacuum degree of the mixture at 0.5 multiplied by 10-5Making into paste under the condition of MPa to obtain the product.
In the invention, the preparation method of the vanadium-plated graphene comprises the following steps:
1) taking graphene oxide, and carrying out coarsening, sensitizing and activating treatment on the graphene oxide in sequence according to a conventional method;
2) reducing the activated graphene oxide in a reducing agent, washing and drying to obtain reduced graphene for later use; the reducing agent is preferably hydrazine hydrate;
3) plating vanadium on the surface of the reduced graphene by adopting a conventional electrodeposition method to prepare vanadium-plated graphene; the parameters of the electrodeposition process are preferably as follows: current density: 1.5-3A/dm2Temperature: the temperature is 32-39 ℃, the pH value is 5.5-7.2, the sulfate of divalent vanadium ions is 58-81 g/L, the sodium dodecyl sulfate is 6.2-7.9 g/L, the nickel chloride is 33-48 g/L, and the deposition rate is 2.5-4 mu m/h;
4) depositing metal nickel ions on the surface of the vanadium-plated graphene by adopting a direct-current magnetron sputtering method to prepare the vanadium-plated graphene loaded with nickel ions; the parameters of the direct current magnetron sputtering method are preferably as follows, the target material is a vanadium-nickel (vanadium-nickel mass ratio is 2: 3) alloy target with the purity of 99.99 percent, the substrate is a glass slide, the voltage power is 0.6-0.8 kV, and the vacuum degree is (1.5-2.1) × 10-4When Pa is needed, argon with the purity of 99.99 percent is introduced as discharge and sputtering gas, the sputtering power is 120-160W, and the deposition time is 3-4.5 min;
5) putting the vanadium-plated graphene loaded with nickel ions into a ball milling tank, and grinding into powder to obtain vanadium-plated graphene powder, wherein the particle size of the powder is preferably 86-112 micrometers.
According to the invention, the inner framework and the filter screen are fixed by spot welding by utilizing the advantages of high welding speed, accurate positioning and no need of welding materials of laser spot welding, the welding spot of 12-16 welding spots is generally required for only 8-9 s, and the welding seam has beautiful quality and no defect; and then coating brazing filler metal paste on other points to be welded, and welding by adopting a vacuum brazing method, wherein on one hand, the vacuum brazing is to heat the workpiece in an integral atmosphere, so that the seawater filter element to be welded is uniformly heated, and the defects of residual stress, hot cracks and the like are not generated in the welding process, on the other hand, the vacuum brazing is implemented in a vacuum environment, and when the liquid brazing filler metal is connected with a stainless steel filter screen and a framework, the defects of air holes, impurities and the like are not easily generated on a brazing seam interface, so that the welding quality and performance are ensured. Meanwhile, in the composite welding method, the heat radiation of the laser and the vacuum environment is not contacted with the stainless steel base material and the brazing filler metal, and the laser and the radiation are used for heating, so that pressure is not required to be applied in the welding process; the stainless steel base metal is easy to generate high-temperature creep deformation, phase change and the like at high temperature, the structure performance of the stainless steel base metal is changed, the performance of a welding joint is reduced, the stainless steel is not melted in the composite welding process, and the structure performance change problem can be avoided;
because the stainless steel seawater filter element with the nickel ions loaded on the surface is added in the composite solder, on one hand, graphene has excellent properties of electricity, heat, mechanics and the like, and simultaneously has low density and good structural stability, the wettability, the heat conductivity and the solderability of the solder can be obviously improved by adding the stainless steel seawater filter element into the solder, the problems of floating indefinite graphene in a solder paste and a liquid solder, uneven solder components and oxide in tissues are prevented by plating vanadium on the surface of the graphene, the tensile strength of the prepared composite solder is greatly enhanced, the tensile strength of a joint is far higher than that of the prior report, on the other hand, the nickel ions are loaded on the surface of the vanadium-plated graphene, when the composite solder is used, the nickel ions are slowly released, and the defects of nitride, carbide and the like in high-nitrogen steel can be inhibited and generated due to the extremely low concentration of the nickel ions, the mechanical property of the joint is improved;
when the laser spot welding is implemented, the initial period of time is only 0.5ms, so that the time for raising the initial power is accurately controlled, and the laser spot welding method has the following advantages: 1) the temperature rise time is short, the welding spot position of the stainless steel filter screen can be accurately found, and the efficiency is high; the utilization rate of the energy of the laser emitter is improved, and the cost is low. The end segment time is only 0.4ms, so that the time of power reduction is accurately controlled, and the following advantages are achieved: 1) the cooling time is short, the range of a welding heat affected zone of the stainless steel filter screen can be accurately controlled, and the defects of penetration welding, welding penetration and the like are prevented; 2) the energy of the laser emitter is saved, the connection quality of the stainless steel filter screen is improved, and energy and consumption are saved;
during vacuum brazing, the vacuum degree is controlled by adopting a vacuum pump and a vacuum gauge, so that on one hand, the whole process is implemented in a vacuum environment, impurity elements and external gas cannot participate in reaction in the welding process, and the obtained joint has no defect, high cleanliness and excellent performance; on the other hand, the vacuum degree is accurately controlled, so that external impurities cannot enter a welding line in the welding process, and the welding quality is high. Meanwhile, the melting temperature of the solder paste is 1047-1239 ℃, and the heat preservation is carried out for 45-55s, so that: because the real temperature of the vacuum brazing furnace is not completely matched with the melting temperature of the brazing filler metal, in order to enable the brazing filler metal to be in a molten state, the furnace temperature is set to be 50-100 ℃ higher than the liquid phase line temperature of the brazing filler metal paste, the solid brazing filler metal paste can be guaranteed to be completely melted into a liquid state to be wetted and spread, the gap between welding points of a stainless steel filter screen and a framework is fully filled by means of capillary action in the brazing process, and the defects of no welding, no brazing and the like can be prevented.
The synergistic regulation and control effect of each element in the brazing filler metal paste used by the invention is as follows:
pd can be mutually dissolved with elements such as nickel, silicon, rhenium, manganese and the like, so that a solid solution can be formed, and the high-temperature resistance strength of the brazing filler metal and the joint is improved; is one of the main elements connecting the steel sides of the aluminum/high nitrogen steel dissimilar materials;
ni can improve the wettability of the brazing filler metal, improve the strength and the corrosion resistance of a brazed joint, purify a brazing seam crystal boundary and improve the processing performance of the brazing filler metal, and is one of the most important elements on the steel side for connecting aluminum/high-nitrogen steel dissimilar materials;
cr can be infinitely dissolved with nickel and manganese, can improve the strength and corrosion resistance of brazing filler metal and joints, and is one of the most important elements for connecting the dissimilar material steel sides of aluminum/high-nitrogen steel;
mn can reduce the melting temperature and improve the wettability of the brazing filler metal, and has a secondary deoxidation effect; meanwhile, the microhardness and the high-temperature strength of the brazing filler metal can be improved;
re is rarely added into the brazing filler metal and is only reported, and the brazing filler metal of the invention adds the rhenium element, thereby improving the joint filling capacity of the brazing filler metal and improving the jointing capacity of the brazing filler metal.
Si can improve the wettability of the solder, refine the texture of the solder and improve the strength of the solder and a soldered joint; can form eutectic with aluminum, the mass fraction of the eutectic point Si is 11.7 percent, and the eutectic point Si is the most important element for connecting the aluminum side of the aluminum/high-nitrogen steel dissimilar material;
b can improve the plasticity of the brazing filler metal and enhance the spreadability and the fluidity of the brazing filler metal, and is one of the most important elements on the aluminum side for connecting aluminum/high-nitrogen steel dissimilar materials;
the vanadium-plated graphene can regulate and control the tissue and weld performance of the brazing filler metal, improve the tensile strength of a joint, enable the mechanical property of the brazing filler metal to be more excellent, and is one of the most important materials for ensuring the connection strength of the stainless steel seawater filter element.
Compared with the prior art, the invention has the following advantages:
1) the steel base material is hardly melted, so that the nitrogen element is not lost, the defect of pores in the traditional welding mode is overcome, and the nitrogen element is hardly lost; moreover, as the steel base material is hardly melted, namely has no deformation, the connection strength and the mechanical property of the joint are improved to a certain extent, and the welded joint is formed very well;
2) the laser and the vacuum radiation are not in contact with the base metal and the brazing filler metal, and pressure is not required to be applied in the welding process through radiation heating; the whole process is implemented in a vacuum environment, so that impurity elements and external gas cannot participate in reaction in the welding process, and the obtained joint has no defect, high cleanliness and excellent performance;
3) according to the invention, due to the low temperature during the laser spot welding-vacuum brazing composite welding of the connecting steel, the generation of nitrides, carbides and carbonitrides at the joint can be effectively prevented to reduce the performance of the connecting steel;
4) during welding in the prior art, the steel base metal is easy to generate high-temperature creep deformation, phase change and the like at high temperature, the structure performance of the steel base metal is changed, and the performance of a welding joint is reduced;
5) the brazing filler metal paste used by the invention contains elements such as palladium, nickel, manganese, chromium and the like, can effectively wet steel, and can be almost infinitely dissolved with a steel base material to form metallurgical bonding, so that the mechanical property of a joint is enhanced.
Detailed Description
The technical solution of the present invention will be further illustrated and described with reference to specific examples.
Example 1
The utility model provides a method of laser spot welding and vacuum brazing hybrid welding stainless steel sea water filter core, treat that the welding position carries out surface preparation at first to the inner frame and the filter screen of stainless steel sea water filter core, then treat the welding position with the anchor clamps is fixed, secondly, adopt laser spot welding to treat that the welding position carries out spot welding according to the filter screen number of turns on the inner frame surface and fixes, later coat in treating the face with solder paste, adopt vacuum brazing to treat the welding position to all the other welding positions except laser spot welding position again at last to accomplish the welding of stainless steel sea water filter core, the operation of vacuum brazing is as follows: 1) assembling the fixed surface to be welded by laser spot welding by using a clamp, coating prefabricated solder paste, and then putting the whole workpiece into a vacuum cavity; 2) the vacuum degree of the vacuum chamber was set to 10-6Pa; 3) setting a temperature control unit, heating to 1047 ℃ to melt the solder paste, and keeping the temperature for 45 s; 4) after the heat preservation is finished, naturally cooling, opening the vacuum cavity air inlet unit when the workpiece to be welded is cooled to room temperature, opening the vacuum cavity unit when the pressure inside and outside the cavity is the same, and taking out the workpiece to finish the welding of the stainless steel seawater filter element;
the specific operation of the laser spot welding is as follows:
1) fixing an inner framework with the diameter of 1.0mm to be welded and a filter screen with the aperture of 6 meshes by using a clamp, and then setting the laser spot welding process parameters as follows: the laser power is 400W, the spot welding time is 120ms, the welding speed is 5mm/s, the focal length of the lens is phi 50 multiplied by 100mm, and the light emitting frequency is 10 HZ;
2) and performing laser spot welding according to the laser spot welding process parameters, enabling the laser power to be increased from 0 to 100% of full power within 0.5ms initially, then continuing for 8.5ms at 100% of full power, completing the laser spot welding work within the continuous time, and then rapidly reducing the laser power from 100% of full power to 0 within 0.4 ms.
The surface pretreatment comprises mechanical polishing, electrolytic polishing solution preparation and electrolytic polishing in sequence, and specifically comprises the following operations:
1) mechanical polishing
The surface of a workpiece to be welded is polished, and the workpiece to be welded is mechanically polished by dry and wet metallographic abrasive paper of 100#, 400#, 600#, 800#, 1000#, 1500# and 2000# in sequence, and then mechanically polished by a gold velvet polishing cloth matched with M1.5 polishing agent;
2) preparing electrolytic polishing solution
Mixing perchloric acid and ethanol according to the volume fraction of 1:4 to obtain an electrolytic polishing solution; the electrolytic polishing solution needs to be prepared 24 hours in advance, and the standing time is not too long, generally not longer than 14 days;
3) electrolytic polishing
Performing electrolytic polishing on the workpiece mechanically polished in the step 1) by using the electrolytic polishing solution prepared in the step 2), wherein the electrolytic polishing direct current voltage is 15V, the current is 1.0A, the temperature is-20 ℃, and the polishing time is 40 s;
4) and after the electrolytic polishing is finished, cleaning the workpiece by using ethanol to remove the acid solution on the surface of the workpiece, thus finishing the surface pretreatment.
In this example, the solder paste used was a composition comprising, by weight, 25 parts Pd, 2.8 parts vanadium-plated graphene, 39 parts Ni, 36 parts Cr, 12 parts Mn, 7 parts Re, 6 parts Si and 2 parts B;
the preparation method of the solder paste comprises the following steps:
1) weighing the components according to the proportion, and ball-milling the components to powder with the particle size of 128 microns for later use;
2) formulating water-based binders
Weighing 36 parts of zinc phosphate, 45 parts of ammonium chloride, 15 parts of polyethylene glycol and 14 parts of butyl cyanoacrylate according to the weight ratio, and uniformly mixing to prepare a water-based binder for later use;
3) weighing 70 parts of the powder prepared in the step 1), 15 parts of distilled water, 15 parts of the water-based binder prepared in the step 2) and 5 parts of acetone according to the weight ratio for later use;
4) mixing the distilled water, the water-based binder and the acetone weighed in the step 3), uniformly stirring until no precipitate is generated, then adding the weighed powder into the mixture, uniformly stirring, and keeping the vacuum degree of the mixture at 0.5 multiplied by 10-5Making into paste under the condition of MPa to obtain the product.
In this embodiment, the preparation method of the vanadium-plated graphene comprises:
1) taking graphene oxide, and carrying out coarsening, sensitizing and activating treatment on the graphene oxide in sequence according to a conventional method;
2) reducing the activated graphene oxide in a reducing agent, washing and drying to obtain reduced graphene for later use; the reducing agent is hydrazine hydrate sold in the market;
3) plating vanadium on the surface of the reduced graphene by adopting a conventional electrodeposition method to prepare vanadium-plated graphene; the parameters of the electrodeposition method are as follows: current density: 1.5A/dm2Temperature: the pH value is 5.5 at 32 ℃, the sulfate of divalent vanadium ions is 58g/L, the lauryl sodium sulfate is 6.2g/L, the nickel chloride is 33g/L, and the deposition rate is 2.5 mu m/h;
4) depositing metal nickel ions on the surface of the vanadium-plated graphene by adopting a direct-current magnetron sputtering method to prepare the vanadium-plated graphene loaded with nickel ions; the parameters of the direct current magnetron sputtering method are that the target material is a vanadium-nickel (the mass ratio of vanadium to nickel is 2: 3) alloy target with the purity of 99.99 percent, the substrate is a glass slide, the voltage power is 0.6kV, the vacuum degree is 1.5 multiplied by 10-4When Pa is needed, argon with the purity of 99.99 percent is introduced as discharge and sputtering gas, the sputtering power is 120W, and the deposition time is 3 min;
5) putting the vanadium-plated graphene loaded with nickel ions into a ball milling tank, and grinding into powder to obtain vanadium-plated graphene powder, wherein the particle size of the powder is 86 microns.
Example 2
A method for welding stainless steel seawater filter core by laser spot welding and vacuum brazing includes such steps as pretreating the surface of the internal skeleton and filter screen to be welded, fixing the part to be welded by fixture, and laser spot weldingSpot welding is carried out on the surface of the inner framework, brazing filler metal paste is coated on the surface to be welded, and finally, the rest positions to be welded except the laser spot welding position are brazed by adopting vacuum brazing, so that the stainless steel seawater filter element is welded, wherein the vacuum brazing is carried out as follows: 1) assembling the fixed surface to be welded by laser spot welding by using a clamp, coating prefabricated solder paste, and then putting the whole workpiece into a vacuum cavity; 2) the vacuum degree of the vacuum chamber was set to 10-4Pa; 3) setting a temperature control unit, heating to 1239 ℃ to melt the brazing filler metal paste, and keeping the temperature for 55 s; 4) after the heat preservation is finished, naturally cooling, opening the vacuum cavity air inlet unit when the workpiece to be welded is cooled to room temperature, opening the vacuum cavity unit when the pressure inside and outside the cavity is the same, and taking out the workpiece to finish the welding of the stainless steel seawater filter element;
the specific operation of the laser spot welding is as follows:
1) fixing an inner framework with the diameter of 2.2mm to be welded and a filter screen with the aperture of 10 meshes by using a clamp, and then setting the laser spot welding process parameters as follows: the laser power is 500W, the spot welding time is 180ms, the welding speed is 8mm/s, the focal length of the lens is phi 50 multiplied by 120mm, and the light emitting frequency is 15 HZ;
2) and performing laser spot welding according to the laser spot welding process parameters, enabling the laser power to be increased from 0 to 100% of full power within 0.5ms initially, then continuing for 9ms at 100% of full power, completing the laser spot welding operation within the continuous time, and then rapidly reducing the laser power from 100% of full power to 0 within 0.4 ms.
The surface pretreatment comprises mechanical polishing, electrolytic polishing solution preparation and electrolytic polishing in sequence, and specifically comprises the following operations:
1) mechanical polishing
The surface of a workpiece to be welded is polished, and the workpiece to be welded is mechanically polished by dry and wet metallographic abrasive paper of 100#, 400#, 600#, 800#, 1000#, 1500# and 2000# in sequence, and then mechanically polished by a gold velvet polishing cloth matched with M1.5 polishing agent;
2) preparing electrolytic polishing solution
Mixing perchloric acid and ethanol according to the volume fraction of 1:4 to obtain an electrolytic polishing solution; the electrolytic polishing solution needs to be prepared 24 hours in advance, and the standing time is not too long, generally not longer than 14 days;
3) electrolytic polishing
Performing electrolytic polishing on the workpiece mechanically polished in the step 1) by using the electrolytic polishing solution prepared in the step 2), wherein the electrolytic polishing direct current voltage is 20V, the current is 1.5A, the temperature is-30 ℃, and the polishing time is 75 s;
4) and after the electrolytic polishing is finished, cleaning the workpiece by using ethanol to remove the acid solution on the surface of the workpiece, thus finishing the surface pretreatment.
In this example, the solder paste used was a composition comprising, by weight, 28 parts Pd, 5.8 parts vanadium-plated graphene, 46 parts Ni, 39 parts Cr, 15 parts Mn, 11 parts Re, 9 parts Si and 5.5 parts B;
the preparation method of the solder paste comprises the following steps:
1) weighing the components according to the proportion, and ball-milling the components to powder with the particle size of 128 microns for later use;
2) formulating water-based binders
Weighing 36 parts of zinc phosphate, 45 parts of ammonium chloride, 15 parts of polyethylene glycol and 14 parts of butyl cyanoacrylate according to the weight ratio, and uniformly mixing to prepare a water-based binder for later use;
3) weighing 70 parts of the powder prepared in the step 1), 15 parts of distilled water, 15 parts of the water-based binder prepared in the step 2) and 5 parts of acetone according to the weight ratio for later use;
4) mixing the distilled water, the water-based binder and the acetone weighed in the step 3), uniformly stirring until no precipitate is generated, then adding the weighed powder into the mixture, uniformly stirring, and keeping the vacuum degree of the mixture at 0.5 multiplied by 10-5Making into paste under the condition of MPa to obtain the product.
In this embodiment, the preparation method of the vanadium-plated graphene comprises:
1) taking graphene oxide, and carrying out coarsening, sensitizing and activating treatment on the graphene oxide in sequence according to a conventional method;
2) reducing the activated graphene oxide in a reducing agent, washing and drying to obtain reduced graphene for later use; the reducing agent is hydrazine hydrate sold in the market;
3) plating vanadium on the surface of the reduced graphene by adopting a conventional electrodeposition method to prepare vanadium-plated graphene; the parameters of the electrodeposition method are as follows: current density: 3A/dm2Temperature: the pH value is 7.2 at 39 ℃, the sulfate of divalent vanadium ions is 81g/L, the lauryl sodium sulfate is 7.9g/L, the nickel chloride is 48g/L, and the deposition rate is 4 mu m/h;
4) depositing metal nickel ions on the surface of the vanadium-plated graphene by adopting a direct-current magnetron sputtering method to prepare the vanadium-plated graphene loaded with nickel ions; the parameters of the direct current magnetron sputtering method are that the target material is a vanadium-nickel (the mass ratio of vanadium to nickel is 2: 3) alloy target with the purity of 99.99 percent, the substrate is a glass slide, the voltage power is 0.8kV, and the vacuum degree is 2.1 multiplied by 10-4When Pa is needed, argon with the purity of 99.99 percent is introduced as discharge and sputtering gas, the sputtering power is 160W, and the deposition time is 4.5 min;
5) putting the vanadium-plated graphene loaded with nickel ions into a ball milling tank, and grinding into powder to obtain vanadium-plated graphene powder, wherein the particle size of the powder is 112 microns.
Example 3
The utility model provides a method of laser spot welding and vacuum brazing hybrid welding stainless steel sea water filter core, treat that the welding position carries out surface preparation at first to the inner frame and the filter screen of stainless steel sea water filter core, then treat the welding position with the anchor clamps is fixed, secondly, adopt laser spot welding to treat that the welding position carries out spot welding according to the filter screen number of turns on the inner frame surface and fixes, later coat in treating the face with solder paste, adopt vacuum brazing to treat the welding position to all the other welding positions except laser spot welding position again at last to accomplish the welding of stainless steel sea water filter core, the operation of vacuum brazing is as follows: 1) assembling the fixed surface to be welded by laser spot welding by using a clamp, coating prefabricated solder paste, and then putting the whole workpiece into a vacuum cavity; 2) the vacuum degree of the vacuum chamber was set to 10-5Pa; 3) setting a temperature control unit, heating to 1143 ℃ to melt the solder paste, and keeping the temperature for 50 s; 4) naturally cooling after the heat preservation is finished, opening the air inlet unit of the vacuum cavity when the workpiece to be welded is cooled to room temperature, and enabling the pressure inside and outside the vacuum cavity to be oppositeMeanwhile, opening the vacuum cavity unit, and taking out the workpiece to complete the welding of the stainless steel seawater filter element;
the specific operation of the laser spot welding is as follows:
1) fixing an inner framework with the diameter of 1.6mm to be welded and a filter screen with the aperture of 8 meshes by using a clamp, and then setting the laser spot welding process parameters as follows: the laser power is 450W, the spot welding time is 150ms, the welding speed is 6.5mm/s, the focal length of the lens is phi 50 multiplied by 110mm, and the light emitting frequency is 12.5 HZ;
2) and performing laser spot welding according to the laser spot welding process parameters, enabling the laser power to be increased from 0 to 100% of full power within 0.5ms initially, then continuing for 8.75ms at 100% of full power, completing the laser spot welding operation within the continuous time, and then rapidly reducing the laser power from 100% of full power to 0 within 0.4 ms.
The surface pretreatment comprises mechanical polishing, electrolytic polishing solution preparation and electrolytic polishing in sequence, and specifically comprises the following operations:
1) mechanical polishing
The surface of a workpiece to be welded is polished, and the workpiece to be welded is mechanically polished by dry and wet metallographic abrasive paper of 100#, 400#, 600#, 800#, 1000#, 1500# and 2000# in sequence, and then mechanically polished by a gold velvet polishing cloth matched with M1.5 polishing agent;
2) preparing electrolytic polishing solution
Mixing perchloric acid and ethanol according to the volume fraction of 1:4 to obtain an electrolytic polishing solution; the electrolytic polishing solution needs to be prepared 24 hours in advance, and the standing time is not too long, generally not longer than 14 days;
3) electrolytic polishing
Performing electrolytic polishing on the workpiece mechanically polished in the step 1) by using the electrolytic polishing solution prepared in the step 2), wherein the electrolytic polishing direct current voltage is 17.5V, the current is 1.25A, the temperature is-25 ℃, and the polishing time is 60 s;
4) and after the electrolytic polishing is finished, cleaning the workpiece by using ethanol to remove the acid solution on the surface of the workpiece, thus finishing the surface pretreatment.
In this example, the solder paste used was composed of, by weight, 26.5 parts of Pd, 4.2 parts of vanadium-plated graphene, 42.5 parts of Ni, 37.5 parts of Cr, 13.5 parts of Mn, 9 parts of Re, 7.5 parts of Si, and 4 parts of B;
the preparation method of the solder paste comprises the following steps:
1) weighing the components according to the proportion, and ball-milling the components to powder with the particle size of 128 microns for later use;
2) formulating water-based binders
Weighing 36 parts of zinc phosphate, 45 parts of ammonium chloride, 15 parts of polyethylene glycol and 14 parts of butyl cyanoacrylate according to the weight ratio, and uniformly mixing to prepare a water-based binder for later use;
3) weighing 70 parts of the powder prepared in the step 1), 15 parts of distilled water, 15 parts of the water-based binder prepared in the step 2) and 5 parts of acetone according to the weight ratio for later use;
4) mixing the distilled water, the water-based binder and the acetone weighed in the step 3), uniformly stirring until no precipitate is generated, then adding the weighed powder into the mixture, uniformly stirring, and keeping the vacuum degree of the mixture at 0.5 multiplied by 10-5Making into paste under the condition of MPa to obtain the product.
In this embodiment, the preparation method of the vanadium-plated graphene comprises:
1) taking graphene oxide, and carrying out coarsening, sensitizing and activating treatment on the graphene oxide in sequence according to a conventional method;
2) reducing the activated graphene oxide in a reducing agent, washing and drying to obtain reduced graphene for later use; the reducing agent is hydrazine hydrate sold in the market;
3) plating vanadium on the surface of the reduced graphene by adopting a conventional electrodeposition method to prepare vanadium-plated graphene; the parameters of the electrodeposition method are as follows: current density: 2.25A/dm2Temperature: the temperature is 35.5 ℃, the pH value is 6.3, the sulfate of divalent vanadium ions is 70g/L, the lauryl sodium sulfate is 7g/L, the nickel chloride is 40g/L, and the deposition rate is 3.3 mu m/h;
4) depositing metal nickel ions on the surface of the vanadium-plated graphene by adopting a direct-current magnetron sputtering method to prepare the vanadium-plated graphene loaded with nickel ions; the parameters of the direct current magnetron sputtering method are that the target material is a vanadium-nickel (vanadium-nickel mass ratio is 2: 3) alloy target with the purity of 99.99 percent, the substrate is a glass slide, the voltage power is 0.7kV, the vacuum degree is 1.8 multiplied by 10 < -4 > Pa, argon with the purity of 99.99 percent is introduced as discharging and sputtering gas, the sputtering power is 140W, and the deposition time is 4 min;
5) putting the vanadium-plated graphene loaded with nickel ions into a ball milling tank, and grinding into powder to obtain vanadium-plated graphene powder, wherein the particle size of the powder is 100 microns.
Claims (5)
1. The utility model provides a method of laser spot welding and vacuum brazing hybrid welding stainless steel sea water filter core, treat that the welding position carries out surface preparation at first to the inner frame and the filter screen of stainless steel sea water filter core, then treat the welding position with the anchor clamps is fixed, secondly, adopt laser spot welding to treat that the welding position is according to the filter screen number of turns on the inner frame surface spot welding fixed, later coat in treating the face with solder paste, adopt vacuum brazing to treat the welding position to all the other welding positions except that laser spot welding position again at last to accomplish the welding of stainless steel sea water filter core, a serial communication port, the operation of vacuum brazing is as follows: 1) assembling the fixed surface to be welded by laser spot welding by using a clamp, coating prefabricated solder paste, and then putting the whole workpiece into a vacuum cavity; 2) the vacuum degree of the vacuum chamber was set to 10-6～10-4Pa; 3) setting a temperature control unit, heating to 1047-1239 ℃ to melt the brazing filler metal paste, and keeping the temperature for 45-55 s; 4) after the heat preservation is finished, naturally cooling, opening the vacuum cavity air inlet unit when the workpiece to be welded is cooled to room temperature, opening the vacuum cavity unit when the pressure inside and outside the cavity is the same, and taking out the workpiece to finish the welding of the stainless steel seawater filter element;
the brazing filler metal paste comprises, by weight, 25-28 parts of Pd, 2.8-5.8 parts of vanadium-plated graphene, 39-46 parts of Ni, 36-39 parts of Cr, 12-15 parts of Mn, 7-11 parts of Re, 6-9 parts of Si and 2-5.5 parts of B.
2. The method for the laser spot welding and vacuum brazing composite welding of the stainless steel seawater filter element according to the claim 1, is characterized in that the laser spot welding is carried out by the following steps:
1) fixing the inner skeleton and the filter screen to be welded by using a clamp, and then setting the laser spot welding process parameters as follows: the laser power is 400-500W, the spot welding time is 120-180 ms, the welding speed is 5-8 mm/s, the focal length of the lens is phi 50 multiplied by 100-phi 50 multiplied by 120mm, and the light emitting frequency is 10-15 HZ;
2) and performing laser spot welding according to the laser spot welding process parameters, enabling the laser power to be increased from 0 to 100% of full power within 0.5ms initially, then continuing for 8.5-9 ms at 100% of full power, completing the laser spot welding within the continuous time, and then rapidly reducing the laser power from 100% of full power to 0 within 0.4 ms.
3. The method for the laser spot welding and vacuum brazing composite welding of the stainless steel seawater filter element according to claim 1, is characterized in that: the surface pretreatment comprises mechanical polishing, electrolytic polishing solution preparation and electrolytic polishing in sequence, and the specific operation is as follows:
1) mechanical polishing
The surface of a workpiece to be welded is polished, and the workpiece to be welded is mechanically polished by dry and wet metallographic abrasive paper of 100#, 400#, 600#, 800#, 1000#, 1500# and 2000# in sequence, and then mechanically polished by a gold velvet polishing cloth matched with M1.5 polishing agent;
2) preparing electrolytic polishing solution
Mixing perchloric acid and ethanol according to the volume fraction of 1:4 to obtain an electrolytic polishing solution;
3) electrolytic polishing
Carrying out electrolytic polishing on the workpiece mechanically polished in the step 1) by using the electrolytic polishing solution prepared in the step 2), wherein the electrolytic polishing direct current voltage is 15-20V, the current is 1.0-1.5A, the temperature is-20 ℃ to-30 ℃, and the polishing time is 40-75 s;
4) and after the electrolytic polishing is finished, cleaning the workpiece by using ethanol to remove the acid solution on the surface of the workpiece, thus finishing the surface pretreatment.
4. The method for laser spot welding and vacuum brazing composite welding of the stainless steel seawater filter element according to claim 1, wherein the preparation method of the solder paste is as follows:
1) weighing the components according to the proportion of claim 1, and ball-milling the components to powder with the particle size of 128 microns for later use;
2) formulating water-based binders
Weighing 36 parts of zinc phosphate, 45 parts of ammonium chloride, 15 parts of polyethylene glycol and 14 parts of butyl cyanoacrylate according to the weight ratio, and uniformly mixing to prepare a water-based binder for later use;
3) weighing 70 parts of the powder prepared in the step 1), 15 parts of distilled water, 15 parts of the water-based binder prepared in the step 2) and 5 parts of acetone according to the weight ratio for later use;
4) mixing the distilled water, the water-based binder and the acetone weighed in the step 3), uniformly stirring until no precipitate is generated, then adding the weighed powder into the mixture, uniformly stirring, and keeping the vacuum degree of the mixture at 0.5 multiplied by 10-5Making into paste under the condition of MPa to obtain the product.
5. The method for laser spot welding and vacuum brazing composite welding of the stainless steel seawater filter element according to claim 1, wherein the preparation method of the vanadium-plated graphene comprises the following steps:
1) taking graphene oxide, and carrying out coarsening, sensitizing and activating treatment on the graphene oxide in sequence according to a conventional method;
2) reducing the activated graphene oxide in a reducing agent, washing and drying to obtain reduced graphene for later use;
3) plating vanadium on the surface of the reduced graphene by adopting a conventional electrodeposition method to prepare vanadium-plated graphene;
4) depositing metal nickel ions on the surface of the vanadium-plated graphene by adopting a direct-current magnetron sputtering method to prepare the vanadium-plated graphene loaded with nickel ions;
5) putting the vanadium-plated graphene loaded with nickel ions into a ball milling tank, and grinding into powder to obtain vanadium-plated graphene powder.
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| CN113102854B (en) * | 2021-03-29 | 2022-11-15 | 浙江浪潮精密机械有限公司 | Automatic continuous brazing device and method for hard alloy cutter |
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