Ultrafine low-oxygen iron-nickel alloy powder and preparation method thereof

Abstract

The invention belongs to the technical field of alloy preparation, and discloses superfine low-oxygen iron-nickel alloy powder and a preparation method thereof. The preparation method comprises the following steps that pure iron and pure nickel are smelted according to a certain mass ratio, after the pure iron and the pure nickel are completely smelted, silicon-calcium particles are added, standing and slag fishing are conducted, and alloy liquid is obtained; the alloy liquid flows into the leakage bag, after the leakage bag is heated, the alloy liquid flows out of the leakage bag, the alloy liquid flowing out generates powdery alloy through water atomization, and after the powdery alloy sinks, the powdery alloy is naturally cooled through water flow; and centrifugally dewatering the cooled powdery alloy to obtain a semi-finished product, carrying out a reduction reaction on the semi-finished product in a reducing atmosphere, and then crushing and screening to obtain the superfine low-oxygen iron-nickel alloy powder. The silicon-calcium particles are matched with the high-temperature reduction reaction, the oxygen content can be reduced, the cost can be reduced, the atomization pressure is ensured by adopting the water atomization spraying disc, the particle size is reduced, the fine powder rate of the product is improved, and the yield is increased.

Description

[0001] This application is a divisional application. The application number of the parent application is 202211500569.5, the application date is November 28, 2022, and the name of the invention is "An ultrafine low-oxygen iron-nickel alloy powder and its preparation method." Technical Field

[0002] The invention relates to the technical field of alloy preparation, and in particular to an ultrafine low-oxygen iron-nickel alloy powder and a preparation method thereof. Background Art

[0003] Iron-nickel alloys are widely used in telecommunications, computers, control systems and other fields because of their good magnetic properties in weak magnetic fields. Currently, the main method for preparing iron-nickel alloy powder in the industry is to use steel belt reducing gas at high temperature and furnace tail cooling water to cool and dry the powder. This method cannot solve the problem of too high oxygen content in the finished product. Therefore, it is urgent to provide a method for preparing iron-nickel alloy powder with low oxygen content. Summary of the invention

[0004] The purpose of the present invention is to provide an ultrafine low-oxygen iron-nickel alloy powder and a preparation method thereof, so as to solve the problem of excessively high oxygen content in finished products in the existing iron-nickel alloy powder preparation process.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing ultrafine low-oxygen iron-nickel alloy powder, comprising the following steps:

[0007] Step 1: Smelt pure iron and pure nickel in a certain mass ratio, add silicon-calcium particles after they are completely melted, let stand, remove slag, and obtain alloy liquid;

[0008] Step 2: The alloy liquid flows into the leakage bag, and after the leakage bag is heated, the alloy liquid flows out of the leakage bag, and the flowing alloy liquid is atomized by water to produce powdered alloy, and the powdered alloy sinks and is naturally cooled by water flow;

[0009] Step 3: The powdered alloy after cooling is centrifugally dehydrated to obtain a semi-finished product, which is subjected to a reduction reaction in a reducing atmosphere, and then crushed and sieved to obtain an ultrafine low-oxygen iron-nickel alloy powder.

[0010] Furthermore, in a method for preparing an ultrafine low-oxygen iron-nickel alloy powder, in step 1, the mass ratio of pure iron to pure nickel is 6.75-7.25:2.75-3.25.

[0011] Furthermore, in a method for preparing ultrafine low-oxygen iron-nickel alloy powder, in step one, the amount of silicon-calcium particles added is 0.3-0.4% of the total mass of pure iron and pure nickel, and the molar ratio of silicon to calcium in the silicon-calcium particles is 2.8-3.2:1.8-2.2.

[0012] Furthermore, in a method for preparing ultrafine low-oxygen iron-nickel alloy powder, in step 1, the smelting temperature is 1620-1680° C., and the standing time is 3-4 minutes.

[0013] Furthermore, in a method for preparing ultrafine low-oxygen iron-nickel alloy powder, in the step 2, the heating temperature is 1620-1680°C.

[0014] Furthermore, in a method for preparing ultrafine low-oxygen iron-nickel alloy powder, in step 2, the water atomization equipment is a water atomization spray disk, the water atomization spray disk has 4 to 8 nozzles, and the water atomization pressure P is 100≤P<150MPa.

[0015] Furthermore, in a method for preparing ultrafine low-oxygen iron-nickel alloy powder, in step three, the rotation speed of centrifugal dehydration is 980 to 1020 r / min, and the time of centrifugal dehydration is 15 to 20 min.

[0016] Furthermore, in a method for preparing ultrafine low-oxygen iron-nickel alloy powder, in step 3, the reducing atmosphere is hydrogen, and the flow rate of the reducing atmosphere is 5.0 to 5.5 m 3 / h, the temperature of the reduction reaction is 710-725°C, and the time of the reduction reaction is 3.5-4h.

[0017] Furthermore, in a method for preparing ultrafine low-oxygen iron-nickel alloy powder, in step three, the mesh size of the sieving is 200 to 300 meshes.

[0018] The invention also provides an ultrafine low-oxygen iron-nickel alloy powder prepared by a method for preparing the ultrafine low-oxygen iron-nickel alloy powder.

[0019] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention uses silicon-calcium particles to better reduce the oxygen content of the iron-nickel alloy powder and reduce costs. The high-temperature reduction reaction of hydrogen further reduces the oxygen content, so that the oxygen content of the final powder product is only 0.13-0.20%;

[0021] (2) The present invention adopts a water atomizing spray plate to prepare powder, which reduces the particle size while ensuring the atomizing pressure. The particle size of the finished powder reaches 1.4 to 2.1 μm, which better improves the fine powder rate of the product. The fine powder rate of the finished powder is above 85%, thereby increasing the output of the product. DETAILED DESCRIPTION

[0022] The present invention provides a method for preparing ultrafine low-oxygen iron-nickel alloy powder, comprising the following steps:

[0023] Step 1: Smelt pure iron and pure nickel in a certain mass ratio, add silicon-calcium particles after they are completely melted, let stand, remove slag, and obtain alloy liquid;

[0024] Step 2: The alloy liquid flows into the ladle, and after the ladle is heated, the alloy liquid flows out of the ladle, and the outflowing alloy liquid is atomized by water to produce powdered alloy, which sinks into the atomization barrel and is naturally cooled by water flow to complete the steel casting;

[0025] Step 3: The powdered alloy after cooling is centrifugally dehydrated to obtain a semi-finished product, which is subjected to a reduction reaction in a reducing atmosphere, and then crushed and sieved to obtain an ultrafine low-oxygen iron-nickel alloy powder.

[0026] In the present invention, the pure iron in step 1 is preferably 99.99% pure iron raw material.

[0027] In the present invention, the pure nickel in step 1 is preferably 99.99% pure nickel raw material.

[0028] In the present invention, the mass ratio of pure iron to pure nickel in step 1 is preferably 6.75-7.25:2.75-3.25, more preferably 6.8-7:3-3.2, and more preferably 7:3.

[0029] In the present invention, the equipment for smelting in step 1 is preferably a medium frequency furnace.

[0030] In the present invention, the addition amount of the silicon-calcium particles in step 1 is preferably 0.3-0.4% of the total mass of pure iron and pure nickel, more preferably 0.34-0.38%, and more preferably 0.35%.

[0031] In the present invention, in the silicon-calcium particles of step one, the molar ratio of silicon to calcium is preferably 2.8-3.2:1.8-2.2, further preferably 3.0-3.2:2, and more preferably 3:2. This is because, in the preparation process of iron-nickel alloy, the prior art generally only adds pure silicon to reduce the oxygen content of the product, wherein the cost of pure silicon is too high, and the oxygen content of the product cannot be reduced more completely, and the purity of the finished powder is affected. The present invention uses silicon-calcium particles, wherein the silicon and calcium elements have a strong affinity with oxygen, especially the calcium element, which not only has a good affinity with the oxygen element, but also has a strong affinity with the sulfur element and the nitrogen element. The present invention uses silicon-calcium particles instead of pure silicon, which better reduces the oxygen content of the finished powder, and at the same time better reduces the production cost, while ensuring the atomization pressure, better improves the fine powder rate of the powder, and increases the output of the finished powder.

[0032] In the present invention, in the step 1, the smelting temperature is preferably 1620-1680°C, more preferably 1640-1670°C, and more preferably 1650°C.

[0033] In the present invention, in the step 1, the standing time is preferably 3 to 4 minutes, more preferably 3 to 3.5 minutes, and more preferably 3 minutes.

[0034] In the present invention, in the step 2, the heating temperature is preferably 1620-1680°C, more preferably 1640-1670°C, and more preferably 1650°C.

[0035] In the present invention, in step 2, the water atomization equipment is preferably a water atomization spray disc.

[0036] In the present invention, the number of nozzles of the water atomization spray disc is preferably 4 to 8, more preferably 6 to 8, and even more preferably 8.

[0037] In the present invention, in the step 2, the pressure P of water atomization is preferably 100≤P<150MPa, more preferably 120≤P<150MPa, and even more preferably 140MPa.

[0038] In the present invention, in the step three, the rotation speed of the centrifugal dehydration is preferably 980 to 1020 r / min, more preferably 990 to 1010 r / min, and more preferably 1000 r / min.

[0039] In the present invention, in the step 3, the time for centrifugal dehydration is preferably 15 to 20 minutes, more preferably 16 to 18 minutes, and more preferably 17 minutes.

[0040] In the present invention, in step 3, the reducing atmosphere is preferably hydrogen.

[0041] In the present invention, in step 3, the flow rate of the reducing atmosphere is preferably 5.0 to 5.5 m 3 / h, more preferably 5.0 to 5.2 m 3 / h, more preferably 5.0m 3 / h.

[0042] In the present invention, in step 3, the temperature of the reduction reaction is preferably 710-725°C, more preferably 712-720°C, and more preferably 716°C.

[0043] In the present invention, in step 3, the reduction reaction time is preferably 3.5 to 4 hours, more preferably 3.6 to 3.8 hours, and more preferably 3.7 hours.

[0044] In the present invention, in the step three, the mesh size of the sieving is preferably 200-300 mesh, further preferably 250-300 mesh, and more preferably 300 mesh.

[0045] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] This embodiment provides a method for preparing ultrafine low-oxygen iron-nickel alloy powder, comprising the following steps:

[0048] Step 1: Put 142.86 kg of 99.99% pure iron raw material and 99.99% pure nickel raw material into a medium frequency furnace at a mass ratio of 7:3, and smelt them at 1650°C. After the materials are completely melted, add 500 g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 3 minutes, remove the residue to obtain alloy liquid;

[0049] Step 2: Prepare a ladle. After the alloy liquid flows into the ladle and is heated to 1650°C, the alloy liquid flows out from the bottom of the ladle. The outflowing alloy liquid column is atomized by high-pressure water in a water atomization spray plate to produce powdered alloy. The water atomization pressure is 140MPa. The powdered alloy sinks to the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is equipped with 8 evenly distributed atomization nozzles;

[0050] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. Centrifugal dehydration is performed for 15 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.0m 3 / h, the temperature of the reduction furnace is 715℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.7h under the action of hydrogen, and then crushed and sieved through 300 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0051] Example 2

[0052] This embodiment provides a method for preparing ultrafine low-oxygen iron-nickel alloy powder, comprising the following steps:

[0053] Step 1: Put 166.67 kg of 99.99% pure iron raw material and 99.99% pure nickel raw material in a mass ratio of 7:3 into a medium frequency furnace, and smelt at 1680°C. After the material is completely melted, add 500 g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 4 minutes, remove the residue to obtain alloy liquid;

[0054] Step 2: Prepare a leaking bag. After the alloy liquid flows into the leaking bag and is heated to 1680℃, the alloy liquid flows out from the bottom of the leaking bag. The outflowing alloy liquid column is atomized by high-pressure water in a water atomization spray plate to produce powdered alloy. The water atomization pressure is 149MPa. The powdered alloy sinks to the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is equipped with 4 evenly distributed atomization nozzles;

[0055] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to the centrifuge. The speed of the centrifuge is 1000r / min. Centrifugal dehydration is performed for 20 minutes to obtain a semi-finished product. The semi-finished product is put into the reduction furnace and hydrogen is introduced into the reduction furnace. The flow rate of hydrogen is 5.5m 3 / h, the temperature of the reduction furnace is 725℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.8h under the action of hydrogen, and then crushed and sieved through 300 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0056] Example 3

[0057] This embodiment provides a method for preparing ultrafine low-oxygen iron-nickel alloy powder, comprising the following steps:

[0058] Step 1: Put 125kg of 99.99% pure iron raw material and 99.99% pure nickel raw material in a mass ratio of 7:3 into a medium frequency furnace, and smelt them at 1620°C. After the materials are completely melted, add 500g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 3 minutes, remove the residue to obtain alloy liquid;

[0059] Step 2: Prepare a leaking bag. After the alloy liquid flows into the leaking bag and is heated to 1620℃, the alloy liquid flows out from the bottom of the leaking bag. The outflowing alloy liquid column is atomized by high-pressure water in a water atomization spray plate to produce powdered alloy. The water atomization pressure is 120MPa. The powdered alloy sinks to the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is equipped with 8 evenly distributed atomization nozzles;

[0060] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. Centrifugal dehydration is performed for 15 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.0m 3 / h, the temperature of the reduction furnace is 710℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.7h under the action of hydrogen, and then crushed and sieved through 200 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0061] Example 4

[0062] This embodiment provides a method for preparing ultrafine low-oxygen iron-nickel alloy powder, comprising the following steps:

[0063] Step 1: Put 156.25kg of 99.99% pure iron raw material and 99.99% pure nickel raw material in a mass ratio of 7:3 into a medium frequency furnace, and smelt at 1660°C. After the material is completely melted, add 500g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 3.5 minutes, remove the residue to obtain alloy liquid;

[0064] Step 2: Prepare a ladle. After the alloy liquid flows into the ladle and is heated to 1660°C, the alloy liquid flows out from the bottom of the ladle. The outflowing alloy liquid column is atomized by high-pressure water in a water atomization spray plate to produce powdered alloy. The water atomization pressure is 135MPa. The powdered alloy sinks to the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is equipped with 6 evenly distributed atomization nozzles;

[0065] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. The centrifugal dehydration is performed for 18 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.2m 3 / h, the temperature of the reduction furnace is 720℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.6h under the action of hydrogen, and then crushed and sieved through 200 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0066] Example 5

[0067] This embodiment provides a method for preparing ultrafine low-oxygen iron-nickel alloy powder, comprising the following steps:

[0068] Step 1: Put 135.14 kg of 99.99% pure iron raw material and 99.99% pure nickel raw material into a medium frequency furnace at a mass ratio of 7:3, and smelt them at 1650°C. After the materials are completely melted, add 500 g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 3 minutes, remove the residue to obtain alloy liquid;

[0069] Step 2: Prepare a ladle. After the alloy liquid flows into the ladle and is heated to 1650°C, the alloy liquid flows out from the bottom of the ladle. The outflowing alloy liquid column is atomized by high-pressure water in a water atomization spray plate to produce powdered alloy. The water atomization pressure is 140MPa. The powdered alloy sinks into the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is equipped with 4 evenly distributed atomization nozzles;

[0070] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. Centrifugal dehydration is performed for 15 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.0m 3 / h, the temperature of the reduction furnace is 710℃, the semi-finished product is subjected to high-temperature reduction reaction for 4h under the action of hydrogen, and then crushed and sieved through 200 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0071] Example 6

[0072] This embodiment provides a method for preparing ultrafine low-oxygen iron-nickel alloy powder, comprising the following steps:

[0073] Step 1: Put 131.58 kg of 99.99% pure iron raw material and 99.99% pure nickel raw material into a medium frequency furnace at a mass ratio of 7:3, and smelt them at 1650°C. After the materials are completely melted, add 500 g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 3 minutes, remove the residue to obtain alloy liquid;

[0074] Step 2: Prepare a ladle. After the alloy liquid flows into the ladle and is heated to 1650°C, the alloy liquid flows out from the bottom of the ladle. The outflowing alloy liquid column is atomized by high-pressure water in a water atomization spray plate to produce powdered alloy. The water atomization pressure is 140MPa. The powdered alloy sinks to the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is equipped with 8 evenly distributed atomization nozzles;

[0075] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. Centrifugal dehydration is performed for 15 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.0m 3 / h, the temperature of the reduction furnace is 715℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.9h under the action of hydrogen, and then crushed and sieved with 300 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0076] Comparative Example 1

[0077] This comparative example provides a method for preparing an iron-nickel alloy powder, comprising the following steps:

[0078] Step 1: Put 142.86 kg of 99.99% pure iron raw material and 99.99% pure nickel raw material into a medium frequency furnace at a mass ratio of 7:3, and smelt them at 1650°C. After the materials are completely melted, a liquid alloy is obtained;

[0079] Step 2: Prepare a ladle. After the alloy liquid flows into the ladle and is heated to 1650°C, the alloy liquid flows out from the bottom of the ladle. The outflowing alloy liquid column is atomized by high-pressure water in a water atomization spray plate to produce powdered alloy. The water atomization pressure is 140MPa. The powdered alloy sinks to the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is equipped with 8 evenly distributed atomization nozzles;

[0080] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. Centrifugal dehydration is performed for 15 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.0m 3 / h, the temperature of the reduction furnace is 715℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.7h under the action of hydrogen, and then crushed and sieved through 300 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0081] Comparative Example 2

[0082] This comparative example provides a method for preparing an iron-nickel alloy powder, comprising the following steps:

[0083] Step 1: Put 142.86 kg of 99.99% pure iron raw material and 99.99% pure nickel raw material into a medium frequency furnace at a mass ratio of 7:3, and smelt them at 1650°C. After the materials are completely melted, add 1000 g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 3 minutes, remove the residue to obtain alloy liquid;

[0084] Step 2: Prepare a ladle. After the alloy liquid flows into the ladle and is heated to 1650°C, the alloy liquid flows out from the bottom of the ladle. The outflowing alloy liquid column is atomized by high-pressure water in a water atomization spray plate to produce powdered alloy. The water atomization pressure is 140MPa. The powdered alloy sinks to the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is equipped with 8 evenly distributed atomization nozzles;

[0085] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. Centrifugal dehydration is performed for 15 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.0m 3 / h, the temperature of the reduction furnace is 715℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.7h under the action of hydrogen, and then crushed and sieved through 300 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0086] Comparative Example 3

[0087] This comparative example provides a method for preparing an iron-nickel alloy powder, comprising the following steps:

[0088] Step 1: Put 142.86 kg of 99.99% pure iron raw material and 99.99% pure nickel raw material into a medium frequency furnace at a mass ratio of 7:3, and smelt them at 1650°C. After the materials are completely melted, add 300 g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 3 minutes, remove the residue to obtain alloy liquid;

[0089] Step 2: Prepare a ladle. After the alloy liquid flows into the ladle and is heated to 1650°C, the alloy liquid flows out from the bottom of the ladle. The outflowing alloy liquid column is atomized by high-pressure water in a water atomization spray plate to produce powdered alloy. The water atomization pressure is 140MPa. The powdered alloy sinks to the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is equipped with 8 evenly distributed atomization nozzles;

[0090] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. Centrifugal dehydration is performed for 15 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.0m 3 / h, the temperature of the reduction furnace is 715℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.7h under the action of hydrogen, and then crushed and sieved through 300 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0091] Comparative Example 4

[0092] This comparative example provides a method for preparing an iron-nickel alloy powder, comprising the following steps:

[0093] Step 1: Put 142.86 kg of 99.99% pure iron raw material and 99.99% pure nickel raw material into a medium frequency furnace at a mass ratio of 7:3, and smelt them at 1650°C. After the materials are completely melted, add 500 g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 3 minutes, remove the residue to obtain alloy liquid;

[0094] Step 2: Prepare a ladle. After the alloy liquid flows into the ladle and is heated to 1650°C, the alloy liquid flows out from the bottom of the ladle. The alloy liquid column that flows out is atomized by a water atomization spray plate to produce a powdered alloy. The pressure of the water atomization is 0MPa. The powdered alloy sinks to the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is provided with 8 evenly distributed atomization nozzles;

[0095] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. Centrifugal dehydration is performed for 15 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.0m3 / h, the temperature of the reduction furnace is 715℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.7h under the action of hydrogen, and then crushed and sieved through 300 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0096] Comparative Example 5

[0097] This comparative example provides a method for preparing an iron-nickel alloy powder, comprising the following steps:

[0098] Step 1: Put 142.86 kg of 99.99% pure iron raw material and 99.99% pure nickel raw material into a medium frequency furnace at a mass ratio of 7:3, and smelt them at 1650°C. After the materials are completely melted, add 500 g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 3 minutes, remove the residue to obtain alloy liquid;

[0099] Step 2: Prepare a ladle. After the alloy liquid flows into the ladle and is heated to 1650°C, the alloy liquid flows out from the bottom of the ladle. The alloy liquid column flows out through a water atomization spray plate and is atomized by low-pressure water to produce a powdered alloy. The water atomization pressure is 50MPa. The powdered alloy sinks to the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is provided with 8 evenly distributed atomization nozzles;

[0100] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. Centrifugal dehydration is performed for 15 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.0m 3 / h, the temperature of the reduction furnace is 715℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.7h under the action of hydrogen, and then crushed and sieved through 300 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0101] Comparative Example 6

[0102] This comparative example provides a method for preparing an iron-nickel alloy powder, comprising the following steps:

[0103] Step 1: Put 142.86 kg of 99.99% pure iron raw material and 99.99% pure nickel raw material into a medium frequency furnace at a mass ratio of 7:3, and smelt them at 1650°C. After the materials are completely melted, add 500 g of silicon-calcium particles, where the molar ratio of silicon to calcium is 3:2. After standing for 3 minutes, remove the residue to obtain alloy liquid;

[0104] Step 2: Prepare a ladle. After the alloy liquid flows into the ladle and is heated to 1650°C, the alloy liquid flows out from the bottom of the ladle. The alloy liquid column flows out through a water atomization spray plate and is atomized by low-pressure water to produce a powdered alloy. The water atomization pressure is 50MPa. The powdered alloy sinks into the atomization barrel and is naturally cooled by water flow to complete the steel casting. Among them, the water atomization spray plate is provided with 4 evenly distributed atomization nozzles.

[0105] Step 3: After the steel pouring is completed, the cooled powdered alloy is transported to a centrifuge at a speed of 1000r / min. Centrifugal dehydration is performed for 15 minutes to obtain a semi-finished product. The semi-finished product is placed in a reduction furnace and hydrogen is introduced into the reduction furnace at a flow rate of 5.0m 3 / h, the temperature of the reduction furnace is 715℃, the semi-finished product is subjected to high-temperature reduction reaction for 3.7h under the action of hydrogen, and then crushed and sieved through 300 mesh to obtain ultrafine low-oxygen iron-nickel alloy powder.

[0106] The data comparison of some preparation conditions of Examples 1 to 6 and Comparative Examples 1 to 6 and the particle size, oxygen content, and fine powder rate of the iron-nickel alloy powder is shown in Table 1:

[0107] Table 1. Data comparison of Examples 1 to 6 and Comparative Examples 1 to 6

[0108]

[0109] It can be seen from the above experimental data that under the same water atomization pressure and number of nozzles, Comparative Example 1 does not use silicon-calcium particles compared with Example 1, Comparative Example 2 uses more silicon-calcium particles than Example 1, and Comparative Example 3 uses fewer silicon-calcium particles than Example 1. Comparative Examples 1 to 3 will all lead to an increase in oxygen content.

[0110] Under the condition of adding the same amount of calcium silicate particles, no pressure is applied to the water atomization in Comparative Example 4 compared with Example 1, a lower water atomization pressure is used in Comparative Example 5 compared with Example 1, and a smaller number of nozzles is used in Comparative Example 6 compared with Comparative Example 5. Comparative Examples 4 to 6 will all lead to an increase in the particle size of the powder. Moreover, under the condition of the same number of nozzles, the greater the water atomization pressure, the smaller the particle size; however, if the number of nozzles is reduced, the particle size is relatively larger, that is, the particle size is inversely proportional to the water atomization pressure. However, since the water atomization pressure P in actual production is less than 150MPa, data higher than the atomization pressure range of the present invention are not used for testing in the comparative examples.

[0111] In summary, the ultrafine low-oxygen iron-nickel alloy powder obtained by the above scheme of the present invention reduces the oxygen content of the finished product while reducing the cost, so that the oxygen content of the finished product is only 0.13-0.20%, the particle size is only 1.4-2.1 μm, and the fine powder rate is above 85%, which can be better applied to various fields.

[0112] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing ultrafine low-oxygen iron-nickel alloy powder, characterized in that: The following steps are involved: Step 1: Smelt pure iron and pure nickel in a certain mass ratio, add silicon-calcium particles after they are completely melted, let stand, remove slag, and obtain alloy liquid; Step 2: The alloy liquid flows into the leakage bag, and after the leakage bag is heated, the alloy liquid flows out of the leakage bag, and the flowing alloy liquid is atomized by water to produce powdered alloy, and the powdered alloy sinks and is naturally cooled by water flow; Step 3: The powdered alloy after cooling is centrifuged and dehydrated to obtain a semi-finished product, the semi-finished product is subjected to a reduction reaction in a reducing atmosphere, and then crushed and sieved to obtain an ultrafine low-oxygen iron-nickel alloy powder; In the step 1, the mass ratio of pure iron to pure nickel is 7:3, the mass ratio of the added amount of silicon calcium particles to the total mass of pure iron is 142.86:0.5, and the standing time is 3 minutes; In the step 2, the water atomization equipment is a water atomization spray disc, the water atomization spray disc has 8 nozzles, and the water atomization pressure P is 140 MPa; In the step 3, the temperature of the reduction reaction is 715° C., and the time of the reduction reaction is 3.7 h.

2. The method for preparing an ultrafine low-oxygen iron-nickel alloy powder according to claim 1, characterized in that: In the step 1, the molar ratio of silicon to calcium in the silicon-calcium particles is 3:

2.

3. The method for preparing an ultrafine low-oxygen iron-nickel alloy powder according to claim 2, characterized in that: In the step 1, the smelting temperature is 1650°C.

4. The method for preparing an ultrafine low-oxygen iron-nickel alloy powder according to claim 1 or 3, characterized in that: In the step 2, the heating temperature is 1650°C.

5. The method for preparing an ultrafine low-oxygen iron-nickel alloy powder according to claim 1, characterized in that: In the step 3, the rotation speed of the centrifugal dehydration is 1000 r / min, and the time of the centrifugal dehydration is 15 min.

6. The method for preparing an ultrafine low-oxygen iron-nickel alloy powder according to claim 1 or 5, characterized in that: In step 3, the reducing atmosphere is hydrogen, and the flow rate of the reducing atmosphere is 5.0m 3 / h.

7. The method for preparing an ultrafine low-oxygen iron-nickel alloy powder according to claim 6, characterized in that: In the step 3, the mesh size of the screening is 300 meshes.

8. Ultrafine low oxygen iron-nickel alloy powder obtained by the method for preparing ultrafine low oxygen iron-nickel alloy powder according to any one of claims 1 to 7.

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