A method for preparing stainless steel powder for sintering porous metal materials

Abstract

The invention relates to a method for preparing stainless steel powder for sintering metal porous materials, comprising the following steps: S1: adding a stainless steel raw material into an induction furnace, adding a slag remover and a deoxidizer for smelting, and obtaining a stainless steel melt after complete smelting; S2: adding the stainless steel melt into a tundish, flowing out through a draft tube, and crushing with water at a pressure of 5-10Mpa and a temperature of 10-30 DEG C to obtain a stainless steel slurry; S3: after the stainless steel slurry is centrifugally dehydrated, it is placed in a vacuum drying furnace with a rotation speed of 3rpm-10rpm for drying, and after drying for 3H-12H, a stainless steel powder is obtained; S4: sieving the stainless steel powder to obtain stainless steel powders of different grades. The invention uses the stainless steel raw material as a source and adopts a water atomization method to prepare a stainless steel powder in a highly irregular shape, with the characteristics of low loose density and low tap density, and is conducive to the control of the porosity, pore size and distribution uniformity of the sintered metal porous material.

Description

Technical Field

[0001] The invention relates to the technical field of metal powder manufacturing, and in particular to a method for preparing stainless steel powder for sintering metal porous materials. Background Art

[0002] Sintered metal porous materials are composed of a metal matrix and a large number of pores. The pores divide the metal phase into many small units. They have a new structure different from traditional materials and are widely used in structural parts in industries such as aerospace, petrochemicals, metallurgical machinery, energy and environmental protection, biopharmaceuticals, and construction, as well as filters, catalysts, and their carriers in processes such as separation, filtration, catalysis, shock absorption, and heat exchange.

[0003] Sintered metal powder porous materials are generally prepared by forming and sintering spherical or irregularly shaped metal powders. The morphology, particle size distribution, loose density and tap density of the metal powder play a decisive role in the pore size, porosity and pore distribution of the sintered metal porous materials. The main methods for preparing metal powders are atomization, which is a powder preparation method that uses a fast-moving fluid impact to break the metal or alloy liquid into fine droplets, and then condense them into solid powder. However, the morphology of metal powders prepared by traditional water atomization or gas atomization is nearly spherical or plump irregular, and the loose density and tap density are high, which is not conducive to improving the control of the porosity, pore size and distribution uniformity of the sintered metal porous materials, resulting in poor performance and rough appearance of the sintered metal porous materials. Summary of the invention

[0004] The purpose of the present invention is to design a method for preparing stainless steel powder for sintered metal porous materials, so that the prepared stainless steel powder has a highly irregular shape, has the characteristics of low loose density and low tap density, and also has good fluidity, which is beneficial to improve the porosity, pore size and distribution uniformity of the sintered metal porous material, so as to solve the problems raised in the background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing stainless steel powder for sintering porous metal materials comprises the following steps:

[0007] S1: Add the stainless steel raw material into the induction furnace, then add the slag remover and deoxidizer, smelt for a period of time, let it stand for 1-3 minutes, remove the slag, and obtain the stainless steel melt; the deoxidizer can take away the oxygen dissolved in the stainless steel melt, forming oxides that are difficult to dissolve in the stainless steel melt, and float to the slag, and discharge the oxides out of the stainless steel melt. The slag remover has good slag catching performance, and can gather and condense the difficult-to-handle slag into a slag layer, which is easy to remove and prevent slag inclusion in the stainless steel melt, thereby reducing the oxygen content in the finished product and avoiding the poor performance and rough appearance of the downstream sintered metal porous material.

[0008] S2: The stainless steel melt is poured into the tundish and flows out through the guide pipe at the bottom of the tundish. The molten alloy is crushed into stainless steel powder droplets by water with a pressure of 4-10Mpa and a temperature of 10-30°C. After cooling and solidification, it settles in the atomization tank to obtain stainless steel slurry. The appropriate setting of the atomization water pressure and temperature enables the morphology of the finished product to form a highly irregular shape, and its particle size distribution, loose density, tap density and flow rate can have better effects, which can improve the control of the porosity, pore size and distribution uniformity of the sintered metal porous material.

[0009] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 3%-8%, and it is placed in a vacuum drying furnace with a rotation speed of 3rpm-10rpm for drying. After drying for 3H-12H, stainless steel powder is obtained; a low-speed vacuum drying furnace is used for drying, so that the stainless steel powder will generate friction with the inner wall of the vacuum drying furnace during drying, further enhancing the irregularity of the finished product morphology.

[0010] S4: Sieve the stainless steel powder to obtain stainless steel powder of different grades, and obtain finished products of common specifications through sieving.

[0011] Preferably, the grade of the stainless steel raw material is one or more of 2205, 316L or 310S.

[0012] Preferably, the slag remover is perlite particles, and the deoxidizer is one or more of silicon calcium particles and metal silicon; metal silicon and silicon calcium particles are used as deoxidizers, silicon reacts with oxygen at high temperature to form silicon dioxide, which is a stable compound and will not have adverse effects on alloy elements in steel. The addition of silicon reduces the oxygen content in the molten pool by reducing oxygen, and at the same time reduces the reaction rate during smelting, making deoxidation safer; calcium in silicon calcium particles reacts with oxygen at high temperature to form calcium oxide, which is a solid that can float in the molten pool and form oxide inclusions, thereby effectively removing oxygen. Perlite particles are used as slag removers, and perlite can expand at high temperatures to form a lightweight porous structure, which makes it have a strong adsorption capacity. In the liquid state of metal, perlite can adsorb metal oxides, impurities and other solid particles, separate them from the metal, and can effectively form a slag layer on the surface of the molten metal to block and adsorb solid impurities and improve the quality and purity of the metal. The combination of deoxidizer and slag remover has a better deoxidation effect and can effectively reduce the oxygen content in the finished product.

[0013] Preferably, the amount of the slag remover in step S1 is added according to the ratio of the stainless steel raw material to the slag remover = 1:0.20-0.40, calculated by mass.

[0014] Preferably, the amount of the deoxidizer in step S1 is added according to the ratio of the stainless steel raw material to the deoxidizer = 1:0.15-0.35, calculated by mass.

[0015] Preferably, the smelting temperature in step S1 is 1660°C to 1700°C, and the temperature of the stainless steel melt during pouring in step S2 is 1650°C to 1660°C.

[0016] Preferably, the material of the guide tube in step S2 is corundum or zirconia; zirconia or corundum has excellent properties such as high strength, high hardness, corrosion resistance and high temperature resistance, so that the stainless steel melt can stably flow from the tundish through the guide tube to the atomizing tank.

[0017] Preferably, the diameter of the guide tube in step S2 is 4.0 mm to 8.0 mm; the size of the guide tube diameter can control the flow rate and flow rate of the stainless steel melt, and cooperate with the atomization water pressure, adopt a low water pressure, large diameter guide tube method or a high water pressure, small diameter guide tube method to maintain the stainless steel melt flowing out of the guide tube at a high flow rate or high flow rate, so that the morphology of the finished product can form a highly irregular shape, the particle size distribution is more uniform, and the loose density is lower.

[0018] Preferably, the temperature of the tundish in step S2 is 900°C to 1200°C.

[0019] Preferably, the screening in step S4 adopts an ultrasonic vibration screening method or an airflow classification screening method.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. Using stainless steel raw materials as the source and adopting the water atomization method, the stainless steel powder prepared is highly irregular in shape, has the characteristics of low bulk density and low tap density, which is conducive to the control of the porosity, pore size and distribution uniformity of sintered metal porous materials. In addition, the price of stainless steel raw materials is low, which can effectively reduce costs;

[0022] 2. Use low water pressure, large diameter guide tube or high water pressure, small diameter guide tube to keep the stainless steel melt flowing out of the guide tube at a high flow rate or high flow rate, so that the morphology of the finished product can form a highly irregular shape, the particle size distribution is more uniform, and the loose density is lower;

[0023] 3. By setting a lower atomization water temperature, the finished product can be formed into a highly irregular shape, with lower bulk density and tap density;

[0024] 4. The centrifugal dehydration device and the vacuum drying furnace are used together. After centrifugal dehydration by the centrifugal dehydration device, a stainless steel powder semi-finished product with a low water content is obtained, and then dried in a vacuum drying furnace, which can effectively reduce the drying time; at the same time, a low-speed vacuum drying furnace is used for drying, so that the stainless steel powder will produce friction with the inner wall of the vacuum drying furnace during drying, further enhancing the irregularity of the finished product morphology, making the loose density and tap density lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 This is a 60 / 80 specification morphology image of the 316L stainless steel powder prepared in Example 1;

[0027] Figure 2 This is a morphology diagram of the 80 / 120 specification of 316L stainless steel powder prepared in Example 1;

[0028] Figure 3 This is a morphology diagram of the 316L stainless steel powder 120 / 170 prepared in Example 1;

[0029] Figure 4 This is a 60 / 80 specification morphology image of 316L stainless steel powder prepared in Comparative Example 4;

[0030] Figure 5 This is a morphology image of 80 / 120 specification of 316L stainless steel powder prepared in Comparative Example 4;

[0031] Figure 6 This is a 120 / 170 specification morphology image of 316L stainless steel powder prepared in Comparative Example 4; DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0033] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are for describing specific embodiments rather than for limiting the scope of protection of the present invention.

[0034] When the embodiment gives a numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs.

[0035] The present invention does not limit the source of raw materials. Unless otherwise specified, the raw materials used are common commercial products.

[0036] Example 1

[0037] The embodiment of the present invention provides a method for preparing stainless steel powder for sintering porous metal materials, comprising the following steps:

[0038] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1680℃ for melting, add 600g silicon calcium particles and 500g perlite particles after the material is completely melted, let it stand for 2min, remove the slag, and obtain 316L stainless steel melt;

[0039] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a corundum flow guide tube with a diameter of 7.0 mm at the bottom of the tundish. The flowing alloy melt is crushed into stainless steel powder droplets by water at a pressure of 7 MPa and a temperature of 20°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0040] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 5 rpm for drying. After drying for 4 hours, stainless steel powder is obtained;

[0041] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0042] Example 2

[0043] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1650℃ for melting, and after all the materials are melted, add 400g silicon calcium particles and 300g perlite particles, let it stand for 1min, remove the slag, and obtain 316L stainless steel melt;

[0044] S2: The 316L stainless steel melt in the above S1 is heated to 1650°C and poured into a tundish at a temperature of 900°C. The melt flows out from a corundum flow guide tube with a diameter of 8.0 mm at the bottom of the tundish. The alloy melt flows out and is crushed into stainless steel powder droplets by water at a pressure of 5 MPa and a temperature of 10°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0045] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 3%, and then it is placed in a vacuum drying furnace with a rotation speed of 3 rpm for drying. After drying for 3 hours, stainless steel powder is obtained;

[0046] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0047] Example 3

[0048] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1700℃ for melting, and after all the materials are melted, add 800g silicon calcium particles and 700g perlite particles, let it stand for 3min, remove the slag, and obtain 316L stainless steel melt;

[0049] S2: The 316L stainless steel melt in the above S1 is heated to 1660°C and poured into a tundish at a temperature of 1200°C. The melt flows out from a corundum flow guide tube with a diameter of 4.0 mm at the bottom of the tundish. The alloy melt flows out and is crushed into stainless steel powder droplets by water at a pressure of 10 MPa and a temperature of 30°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0050] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 8%, and then it is placed in a vacuum drying furnace with a rotation speed of 10 rpm for drying. After drying for 12 hours, stainless steel powder is obtained;

[0051] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0052] Example 4

[0053] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1670℃ for melting, and after all the materials are melted, add 700g silicon calcium particles and 600g perlite particles, let it stand for 3min, remove the slag, and obtain 316L stainless steel melt;

[0054] S2: The 316L stainless steel melt in the above S1 is heated to 1660°C and poured into a tundish at a temperature of 1000°C. The melt flows out from a zirconia flow guide tube with a diameter of 6.0 mm at the bottom of the tundish. The flowing alloy melt is crushed into stainless steel powder droplets by water at a pressure of 6 MPa and a temperature of 20°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0055] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 4%, and then it is placed in a vacuum drying furnace with a rotation speed of 8 rpm for drying. After drying for 6 hours, stainless steel powder is obtained;

[0056] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh screens are selected. The air flow classification screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0057] Example 5

[0058] S1: Add 200kg 2205 rods into an induction furnace and heat to 1680℃ for melting. After all the materials are melted, add 600g metal silicon particles and 500g perlite particles, let stand for 2min, remove the slag, and obtain 316L stainless steel melt;

[0059] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a corundum flow guide tube with a diameter of 7.0 mm at the bottom of the tundish. The flowing alloy melt is crushed into stainless steel powder droplets by water at a pressure of 7 MPa and a temperature of 20°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0060] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 5 rpm for drying. After drying for 4 hours, stainless steel powder is obtained;

[0061] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 2205 stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0062] Example 6

[0063] S1: Add 200kg 310S rods into the induction furnace, heat to 1680℃ for melting, add 300g silicon calcium particles, 300g metal silicon and 500g perlite particles after all the materials are melted, let stand for 2min, remove the slag, and obtain 310S stainless steel melt;

[0064] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a corundum or zirconium oxide flow guide tube with a diameter of 7.0 mm at the bottom of the tundish. The alloy melt flows out and is crushed into stainless steel powder droplets by water at a pressure of 7 MPa and a temperature of 20°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0065] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 5 rpm for drying. After drying for 4 hours, stainless steel powder is obtained;

[0066] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh screens are selected, and an ultrasonic vibration screening method or an air flow classification screening method is adopted to obtain 310S stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0067] Example 7

[0068] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1680℃ for melting, add 600g silicon calcium particles and 500g perlite particles after the material is completely melted, let it stand for 2min, remove the slag, and obtain 316L stainless steel melt;

[0069] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a corundum flow guide tube with a diameter of 4.0 mm at the bottom of the tundish. The alloy melt flows out and is crushed into stainless steel powder droplets by water at a pressure of 7 MPa and a temperature of 20°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0070] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 5 rpm for drying. After drying for 4 hours, stainless steel powder is obtained;

[0071] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0072] Example 8

[0073] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1680℃ for melting, add 600g silicon calcium particles and 500g perlite particles after the material is completely melted, let it stand for 2min, remove the slag, and obtain 316L stainless steel melt;

[0074] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a corundum flow guide tube with a diameter of 7.0 mm at the bottom of the tundish. The alloy melt flows out and is crushed into stainless steel powder droplets by water at a pressure of 5 MPa and a temperature of 20°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0075] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 5 rpm for drying. After drying for 4 hours, stainless steel powder is obtained;

[0076] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0077] Example 9

[0078] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1680℃ for melting, add 600g silicon calcium particles and 500g perlite particles after the material is completely melted, let it stand for 2min, remove the slag, and obtain 316L stainless steel melt;

[0079] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a corundum flow guide tube with a diameter of 7.0 mm at the bottom of the tundish. The flowing alloy melt is crushed into stainless steel powder droplets by water at a pressure of 7 MPa and a temperature of 20°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0080] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 8 rpm for drying. After drying for 6 hours, stainless steel powder is obtained;

[0081] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0082] Example 10

[0083] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1680℃ for melting, add 600g silicon calcium particles and 500g perlite particles after the material is completely melted, let it stand for 2min, remove the slag, and obtain 316L stainless steel melt;

[0084] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a corundum flow guide tube with a diameter of 7.0 mm at the bottom of the tundish. The flowing alloy melt is crushed into stainless steel powder droplets by water at a pressure of 7 MPa and a temperature of 10°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0085] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 5 rpm for drying. After drying for 4 hours, stainless steel powder is obtained;

[0086] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0087] Comparative Example 1

[0088] A method for preparing stainless steel powder for sintering porous metal materials comprises the following steps:

[0089] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1680℃ for melting, add 600g silicon calcium particles and 500g perlite particles after the material is completely melted, let it stand for 2min, remove the slag, and obtain 316L stainless steel melt;

[0090] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a corundum flow guide tube with a diameter of 10 mm at the bottom of the tundish. The alloy melt flows out and is crushed into stainless steel powder droplets by water at a pressure of 12 MPa and a temperature of 20°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0091] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 1 rpm for drying. After drying for 15 hours, stainless steel powder is obtained;

[0092] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0093] Comparative Example 2

[0094] A method for preparing stainless steel powder for sintering porous metal materials comprises the following steps:

[0095] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1680℃ for melting, add 600g silicon calcium particles and 500g perlite particles after the material is completely melted, let it stand for 2min, remove the slag, and obtain 316L stainless steel melt;

[0096] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a 2mm diameter corundum flow guide tube at the bottom of the tundish. The flowing alloy melt is crushed into stainless steel powder droplets by water at a pressure of 2Mpa and a temperature of 20°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0097] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 1 rpm for drying. After drying for 15 hours, stainless steel powder is obtained;

[0098] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0099] Comparative Example 3

[0100] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1680℃ for melting, add 600g silicon calcium particles and 500g perlite particles after the material is completely melted, let it stand for 2min, remove the slag, and obtain 316L stainless steel melt;

[0101] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a corundum flow guide tube with a diameter of 7.0 mm at the bottom of the tundish. The flowing alloy melt is crushed into stainless steel powder droplets by water at a pressure of 7 MPa and a temperature of 20°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0102] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 15 rpm for drying. After drying for 4 hours, stainless steel powder is obtained;

[0103] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0104] Comparative Example 4

[0105] The embodiment of the present invention provides a method for preparing stainless steel powder for sintering porous metal materials, comprising the following steps:

[0106] S1: Add 200kg 316L bar material into the induction furnace, heat it to 1680℃ for melting, add 600g silicon calcium particles and 500g perlite particles after the material is completely melted, let it stand for 2min, remove the slag, and obtain 316L stainless steel melt;

[0107] S2: The 316L stainless steel melt in the above S1 is heated to 1655°C and poured into a tundish at a temperature of 1100°C. The melt flows out from a corundum flow guide tube with a diameter of 7.0 mm at the bottom of the tundish. The flowing alloy melt is crushed into stainless steel powder droplets by water at a pressure of 7 MPa and a temperature of 45°C. After cooling and solidification, the droplets are settled in an atomizing tank to obtain a stainless steel slurry.

[0108] S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 5%, and then it is placed in a vacuum drying furnace with a rotation speed of 5 rpm for drying. After drying for 4 hours, stainless steel powder is obtained;

[0109] S4: The stainless steel powder is screened, and the semi-finished powder after drying is screened, and 60 mesh, 80 mesh, 120 mesh, and 170 mesh sieves are selected, and an ultrasonic vibration screening method is adopted to obtain 316L stainless steel powder finished powders of three specifications of 60 / 80, 80 / 120, and 120 / 170.

[0110] Take some samples of the stainless steel powder finished products of different specifications in the above Examples 1-10 and Comparative Examples 1-4, observe their appearance and properties, and test their loose density, tap density and flow rate.

[0111] The appearance and morphology were observed by scanning electron microscopy (SEM).

[0112] The bulk density shall be determined in accordance with the provisions of GB / T 1479.1-2011;

[0113] The tap density is determined in accordance with the provisions of GB / T 5162-2021;

[0114] The flow rate is measured in accordance with the provisions of GB / T1482-2010;

[0115] The test results are shown in Table 1 below:

[0116] From the data analysis of Table 1, it can be seen that the embodiment is better than the comparative example as a whole. At the same atomization temperature and the rotation speed of the vacuum drying furnace, the comparative example 1 adopts a high water pressure and a large diameter guide tube compared with the embodiment 1, and the comparative example 2 adopts a low water pressure and a small diameter guide tube compared with the embodiment 1. The comparative examples 1-2 all lead to irregular shapes of finished products, reduced flow rate, increased bulk density and tap density; the comparative example 3 adopts a higher rotation speed than the embodiment 1 vacuum drying furnace, the finished product morphology is nearly irregular, the flow rate is reduced, and the bulk density and tap density are increased. This is because the rotation speed of the vacuum drying furnace is too fast, the friction between the stainless steel powder and the inner wall of the vacuum drying furnace is reduced, and the molding of the finished product morphology cannot be effectively further enhanced; the comparative example 4 adopts a higher atomization temperature than the embodiment 1, the finished product morphology is nearly irregular, the bulk density and tap density are significantly increased, and at the same time Figure 4-6 and Figure 1-3 contrast, Figure 4-6 The irregularity is greater than Figure 1-3 The lower the particle size, the rougher the appearance, the poorer the performance of the sintered metal porous material and the rougher the appearance; the stainless steel powders prepared in Comparative Examples 1-4 cannot meet the performance requirements for preparing sintered metal porous materials.

[0117] In Example 7 of the present application, a smaller guide tube diameter is used than in Example 1, the flow rate is reduced, and the bulk density and tap density are increased; in Example 8, a smaller atomization pressure is used than in Example 1, the flow rate is increased, and the bulk density and tap density are reduced; in Example 9, a higher rotation speed is used in the vacuum drying furnace than in Example 1, the flow rate is reduced, and the bulk density and tap density are increased; in Example 10, a lower atomization water temperature is used than in Example 1, the flow rate is reduced, and the bulk density and tap density are increased; it is explained that the guide tube diameter, atomization pressure, the rotation speed of the vacuum drying furnace and the atomization water temperature will affect the particle size distribution, bulk density and tap density of the finished product; in Examples 1-10 of the present application, the atomization water pressure is controlled to be 4-10Mpa, the diameter of the guide tube is 4.0mm~8.0mm, and a low water pressure, large diameter guide tube method or a high water pressure, small diameter guide tube method is used, so that the morphology of the finished product can form a highly irregular shape, the particle size distribution is more uniform, and the bulk density is lower, meeting the performance requirements of sintered metal porous materials.

[0118] The present application uses stainless steel raw materials as a source and adopts a water atomization method to prepare stainless steel powder with a highly irregular shape, low loose density and low tap density, which is beneficial to the control of the porosity, pore size and distribution uniformity of sintered metal porous materials. In addition, the stainless steel raw materials are inexpensive and can effectively reduce costs.

[0119] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing stainless steel powder for sintering porous metal materials, characterized in that: The steps include: S1: Add the stainless steel raw material into the induction furnace, then add the slag remover and deoxidizer for smelting. After complete smelting, let it stand for 1-3 minutes, remove the slag and obtain the stainless steel melt; S2: pouring the stainless steel melt into the tundish, flowing out through the guide pipe at the bottom of the tundish, and crushing the flowing alloy melt into stainless steel powder droplets by water with a pressure of 5-10Mpa and a temperature of 10-30°C, and then settling in the atomization tank after cooling and solidification to obtain stainless steel slurry; S3: After the stainless steel slurry is added to a centrifugal dehydration device for centrifugal dehydration, the moisture content is 3%-8%, and then it is placed in a vacuum drying furnace with a rotation speed of 3rpm-10rpm for drying. After drying for 3H-12H, stainless steel powder is obtained; S4: screening the stainless steel powder to obtain stainless steel powders of different grades; In step S2, the diameter of the guide tube is 4.0 mm to 8.0 mm; and a low water pressure, large diameter guide tube method or a high water pressure, small diameter guide tube method is adopted to maintain a high flow rate or high flow velocity of the stainless steel melt flowing out of the guide tube.

2. The method for preparing stainless steel powder for sintered porous metal material according to claim 1, characterized in that: The grades of the stainless steel raw materials are one or more of 2205, 316L or 310S.

3. The method for preparing stainless steel powder for sintered porous metal material according to claim 1, characterized in that: The deslagging agent is perlite particles, and the deoxidizing agent is one or more of silicon-calcium particles and metallic silicon.

4. The method for preparing stainless steel powder for sintered porous metal material according to claim 1, characterized in that: The amount of the deslagging agent in step S1 is added according to the ratio of the stainless steel raw material to the deslagging agent = 1:0.20-0.40, calculated by mass.

5. The method for preparing stainless steel powder for sintered porous metal material according to claim 1, characterized in that: The amount of the deoxidizer in step S1 is added according to the ratio of the stainless steel raw material to the deoxidizer = 1:0.15-0.35, calculated by mass.

6. The method for preparing stainless steel powder for sintered porous metal material according to claim 1, characterized in that: The smelting temperature in step S1 is 1660°C to 1700°C, and the temperature of the stainless steel melt during pouring in step S2 is 1650°C to 1660°C.

7. The method for preparing stainless steel powder for sintered porous metal material according to claim 1, characterized in that: In step S2, the material of the flow guide tube is corundum or zirconium oxide.

8. The method for preparing stainless steel powder for sintered porous metal material according to claim 1, characterized in that: In step S2, the temperature of the tundish is 900°C to 1200°C.

9. The method for preparing stainless steel powder for sintered porous metal material according to claim 1, characterized in that: The screening in step S4 adopts an ultrasonic vibration screening method or an airflow classification screening method.

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