Method for recycling of plasma rotating electrode atomized residual billets

Abstract

This invention relates to a method for recycling residual feedstock from plasma rotating electrode atomization. The invention addresses the problems of low material utilization, low powder yield, and high processing costs associated with current plasma rotating electrode atomization methods for producing powders from titanium alloy, high-temperature alloy, and titanium-based composite material rods. The method involves: preparing a cylindrical graphite mold; manufacturing a graphite ring; sanding the sides of the feedstock with sandpaper; sanding the conical bottom surface of the feedstock with sandpaper; sanding the bottom and bottom sides of the feedstock; assembling the feedstock; inserting the press head into the cylindrical graphite mold and sintering at high temperature; and turning the bottom and bottom sides of the feedstock on a lathe, thus completing the recycling of the residual feedstock from plasma rotating electrode atomization. This invention significantly improves material utilization, reduces the proportion of machining, and further lowers the cost of preparing titanium alloy and titanium-based composite powders using the plasma rotating electrode atomization method.

Description

Technical Field

[0001] This invention specifically relates to a method for recycling residual material heads from plasma rotating electrode atomization. Background Technology

[0002] Plasma rotating electrode atomization technology is a relatively advanced technology for manufacturing spherical metal powders. It involves bombarding the end face of a metal rod with a plasma arc to melt it, while a motor drives the rod to rotate at high speed. Under centrifugal force, the molten metal droplets are ejected and rapidly solidify into spherical metal powder under the cooling effect of an inert gas. Because this method utilizes centrifugal force to break up the metal droplets, there is minimal gas-liquid interaction, resulting in powders with high sphericity, few hollow particles, low gas content, and high powder quality. It has long been used to prepare powders of titanium alloys, nickel-based superalloys, cobalt-based superalloys, stainless steel, and refractory metals.

[0003] Because the raw material bars need to rotate at high speed, they are usually connected to the rotating shaft with bolts. Machining threads on the bar-shaped billets generates a large amount of metal shavings, which not only wastes materials but also brings difficulties to machining, especially for high-hardness, high-value metals, significantly increasing costs. Furthermore, because the machine tool and ionization chamber are separate designs, the connecting parts of the raw material bars and areas near the connecting parts cannot enter the ionization chamber for melting and powdering; the remaining portion is called the scrap head. For a billet used for powdering, the scrap head can account for 10% to 20% of the weight. The remaining scrap head is often discarded or remelted, resulting in significant waste and increasing powder costs. Therefore, there is an urgent need for a method to recycle and reuse the scrap head remaining from plasma rotating electrode atomization. Summary of the Invention

[0004] The present invention aims to address the problems of low material utilization, low powder output, and high processing costs in the current plasma rotating electrode atomization method for producing powder from raw material rods of titanium alloys, high-temperature alloys, and titanium-based composite materials. The invention provides a method for recycling residual material heads from plasma rotating electrode atomization.

[0005] The method for recycling residual feed heads from plasma rotating electrode atomization is completed according to the following steps:

[0006] 1. Prepare a cylindrical graphite mold according to the dimensions of the bar billet; manufacture graphite rings according to the dimensions of the sprue.

[0007] 2. Use sandpaper to roughen the surface of the material head;

[0008] 3. Sand the bottom conical surface of the sprue until smooth;

[0009] 4. Use a polishing machine to grind the bottom and bottom sides of the material head to make the contact area between the material head and the raw material powder smooth;

[0010] 5. Place a graphite pad at the bottom of the cylindrical graphite mold, then place a graphite ring, and place graphite paper on the inner circle of the graphite ring and the part that contacts the material head.

[0011] 6. Place the feedstock threaded downwards into the graphite ring, and wrap the side of the feedstock with graphite paper to isolate the cylindrical graphite mold and the raw material powder;

[0012] 7. Fill the cylindrical graphite mold with raw material powder to cover the material head, then cover the raw material powder with graphite paper and press in the graphite gasket.

[0013] 8. Insert the pressure head into the cylindrical graphite mold and place it in a vacuum hot pressing sintering furnace for sintering at high temperature;

[0014] 9. Remove the threaded bar obtained from the sintering from the cylindrical graphite mold, and use a lathe to turn the bottom and bottom side of the bar head by 2-30 mm until a metallic luster is achieved. This completes the recycling of the residual bar head from the plasma rotating electrode atomization.

[0015] The beneficial effects of this invention are as follows: This invention achieves the recycling of feedstock in the plasma rotating electrode atomization method through a special mold and powder addition method, significantly improving the utilization rate of raw material rods for plasma rotating electrode atomization, reducing the preparation cycle, greatly reducing production costs, and simplifying the process. The rods prepared by this invention have no obvious defects and have a dense microstructure, meeting the requirements for powder production by the plasma rotating electrode atomization method. Attached Figure Description

[0016] Figure 1 This is a morphological and dimensional diagram of graphite rings;

[0017] Figure 2 This is a morphological and dimensional diagram of the material head;

[0018] Figure 3 This is an assembly diagram of a cylindrical graphite mold, a graphite ring, a feed head, and raw material powder.

[0019] Figure 4 A macroscopic view of the threaded bar obtained by sintering;

[0020] Figure 5 A macroscopic view of the finished product of a threaded bar stock after machining;

[0021] Figure 6 Microscopic morphology of a finished product made from threaded bar stock after machining;

[0022] Figure 7 Microscopic cross-sectional morphology of the raw material powder segment of a threaded bar stock finished product. Detailed Implementation

[0023] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0024] Specific Implementation Method 1: The method for recycling residual material heads from plasma rotating electrode atomization in this implementation method is completed according to the following steps:

[0025] 1. Prepare a cylindrical graphite mold according to the dimensions of the bar billet; manufacture graphite rings according to the dimensions of the sprue.

[0026] 2. Use sandpaper to roughen the surface of the material head;

[0027] 3. Sand the bottom conical surface of the sprue until smooth;

[0028] 4. Use a polishing machine to grind the bottom and bottom sides of the material head to make the contact area between the material head and the raw material powder smooth;

[0029] 5. Place a graphite pad at the bottom of the cylindrical graphite mold, then place a graphite ring, and place graphite paper on the inner circle of the graphite ring and the part that contacts the material head.

[0030] 6. Place the feedstock threaded downwards into the graphite ring, and wrap the side of the feedstock with graphite paper to isolate the cylindrical graphite mold and the raw material powder;

[0031] 7. Fill the cylindrical graphite mold with raw material powder to cover the material head, then cover the raw material powder with graphite paper and press in the graphite gasket.

[0032] 8. Insert the pressure head into the cylindrical graphite mold and place it in a vacuum hot pressing sintering furnace for sintering at high temperature;

[0033] 9. Remove the threaded bar obtained from the sintering from the cylindrical graphite mold, and use a lathe to turn the bottom and bottom side of the bar head by 2-30 mm until a metallic luster is achieved. This completes the recycling of the residual bar head from the plasma rotating electrode atomization.

[0034] This implementation method greatly improves the utilization rate of materials, reduces the proportion of machining, and further reduces the cost of preparing titanium alloys and titanium-based composite powders by plasma rotating electrode atomization.

[0035] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the inner diameter of the graphite ring in step one is 1-5 mm larger than the inner diameter of the feed thread, the outer diameter of the graphite ring is 0.5-3 mm smaller than the inner diameter of the cylindrical graphite mold, and the height of the graphite ring is 2-5 mm higher than the feed thread. Everything else is the same as in Specific Implementation Method One.

[0036] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One in that the outer diameter of the cylindrical graphite mold described in step one is 50–80 mm. Everything else is the same as in Specific Implementation Method One.

[0037] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method One in that: in step two, the sandpaper used is selected between 120# and 5000#; in step three, the sandpaper used is selected between 120# and 5000#. Everything else is the same as in Specific Implementation Method One.

[0038] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method One in that the polishing disc speed of the grinding and polishing machine described in step four is 100-600 r / min. Everything else is the same as in Specific Implementation Method One.

[0039] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method One in that the raw material selected in step six is ​​TA15 titanium alloy, pure Ti, Ti60 titanium alloy, GH3230 nickel-based superalloy, GH3536 nickel-based superalloy, IN718 nickel-based superalloy, IN738 nickel-based superalloy, titanium-based composite material with 0.5–10 vol.% TiB added, or titanium-based composite material with 0.5–10 vol.% TiC added; the matrix of the titanium-based composite material is TC4 titanium alloy, TA15 titanium alloy, pure Ti, or Ti60 titanium alloy. Everything else is the same as in Specific Implementation Method One.

[0040] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method One in that the raw material powder mentioned in step seven is TA15 titanium alloy, pure Ti, Ti60 titanium alloy, GH3230 nickel-based superalloy, GH3536 nickel-based superalloy, IN718 nickel-based superalloy, IN738 nickel-based superalloy, titanium-based composite material with 0.5–10 vol.% TiB added, or titanium-based composite material with 0.5–10 vol.% TiC added; the matrix of the titanium-based composite material is TC4 titanium alloy, TA15 titanium alloy, pure Ti, or Ti60 titanium alloy. Everything else is the same as in Specific Implementation Method One.

[0041] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method One in that the sintering parameters at high temperature in step eight are: sintering temperature of 1200–1400℃ and sintering time of 1–4 hours. Everything else is the same as in Specific Implementation Method One.

[0042] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that the sintering parameters in step eight at high temperature are: sintering temperature is 1300℃, and sintering time is 1 hour. Everything else is the same as in Specific Implementation Method Eight.

[0043] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method One in that: in step nine, the bottom of the workpiece head is machined by 2-10 mm, and the bottom side is machined by 2-10 mm. Everything else is the same as in Specific Implementation Method One.

[0044] The beneficial effects of the present invention are verified by the following embodiments:

[0045] Example 1: The method for recycling residual feed heads from plasma rotating electrode atomization is completed according to the following steps:

[0046] 1. Prepare a cylindrical graphite mold with an inner diameter of 77mm according to the dimensions of the bar billet; manufacture a graphite ring according to the size of the material head; the inner diameter of the graphite ring is 1mm larger than the inner diameter of the material head thread, the outer diameter of the graphite ring is 0.5mm smaller than the inner diameter of the cylindrical graphite mold, and the height of the graphite ring is 2mm higher than the material head thread.

[0047] 2. Use 120# sandpaper to roughen the surface of the material head; that is, sand until the surface scratches match the sandpaper grade.

[0048] 3. Use 120# sandpaper to polish the bottom conical surface of the material head until the surface is smooth;

[0049] 4. Use a polishing machine to polish the bottom and bottom sides of the material head. The polishing disc rotates at 200 r / min to make the contact area between the material head and the raw material powder smooth.

[0050] 5. Place a graphite pad at the bottom of the cylindrical graphite mold, then place a graphite ring, and place graphite paper on the inner circle of the graphite ring and the part that contacts the material head.

[0051] 6. Place the TC4 feedstock with the thread facing down into the graphite ring, and wrap the side of the feedstock with graphite paper to isolate the cylindrical graphite mold and the raw material powder.

[0052] 7. Fill the cylindrical graphite mold with TC4 raw material powder to cover the material head, then cover the raw material powder with graphite paper and press in the graphite gasket.

[0053] 8. Place the pressure head into the cylindrical graphite mold and put it into a vacuum hot pressing sintering furnace, and sinter at 1300℃ for 1 hour;

[0054] 9. Remove the threaded bar obtained from the sintering from the cylindrical graphite mold, and use a lathe to cut 5mm from the bottom of the bar head and 2mm from the bottom side until a metallic luster is achieved. This completes the recycling of the residual bar head from the plasma rotating electrode atomization.

[0055] Example 1: The method for recycling residual feed heads from plasma rotating electrode atomization is completed according to the following steps:

[0056] 1. Prepare a cylindrical graphite mold with an inner diameter of 77mm according to the dimensions of the bar billet; manufacture a graphite ring according to the size of the material head; the inner diameter of the graphite ring is 1mm larger than the inner diameter of the material head thread, the material head thread is M30, the outer diameter of the graphite ring is 0.5mm smaller than the inner diameter of the cylindrical graphite mold, and the height of the graphite ring is 2mm higher than the material head thread.

[0057] 2. Use 320# sandpaper to roughen the surface of the material head; that is, sand until the surface scratches match the sandpaper grade.

[0058] 3. Use 320# sandpaper to polish the bottom conical surface of the material head until the surface is smooth;

[0059] 4. Use a polishing machine to polish the bottom and bottom sides of the material head. The polishing disc rotates at 600 r / min to make the contact area between the material head and the raw material powder smooth.

[0060] 5. Place a graphite pad at the bottom of the cylindrical graphite mold, then place a graphite ring, and place graphite paper on the inner circle of the graphite ring and the part that contacts the material head.

[0061] 6. Place the TA15 sprue with the thread facing down into the graphite ring, and wrap the side of the sprue with graphite paper to isolate the cylindrical graphite mold and the raw material powder.

[0062] 7. Fill the cylindrical graphite mold with 1 vol.% TiB / TA15 raw material powder to cover the material head, then cover the raw material powder with graphite paper and press in the graphite gasket.

[0063] 8. Place the pressure head into the cylindrical graphite mold and put it into a vacuum hot pressing sintering furnace, and sinter at 1300℃ for 2 hours;

[0064] 9. Remove the threaded bar obtained from the sintering from the cylindrical graphite mold, and use a lathe to cut 5mm from the bottom of the bar head and 2mm from the bottom side until a metallic luster is achieved. This completes the recycling of the residual bar head from the plasma rotating electrode atomization.

[0065] Tissue samples measuring 4mm × 7mm × 7mm were cut from the rod obtained in Example 2. After being polished with 320#, 600#, 1000#, 1500#, and 2000# sandpaper, the samples were polished with chromium oxide polishing solution, etched with Kroll reagent for 10 seconds, and observed under a scanning electron microscope. Figure 5 As can be seen, the material is dense, with TiB whiskers uniformly distributed within the TA15 matrix. The powder obtained by plasma spin physicochemical method is shown in the image. Figure 6 As shown, after being polished with 320#, 600#, 1000#, 1500#, and 2000# sandpaper, the powder was polished with chromium oxide polishing solution, etched with Kroll reagent for 10 seconds, and the cross-section of the powder was observed under a scanning electron microscope. Figure 7As shown in the figure, Figure a is a macroscopic morphology of the composite powder, Figure b is a magnified view of the composite powder morphology, Figure c is a cross-sectional morphology of the composite powder, and Figure d is a magnified view of the cross-sectional morphology of the composite powder. It can be observed that the whiskers are well distributed and the microstructure is uniform in the cross-sectional morphology.

Claims

1. A method for recycling residual material from plasma rotating electrode atomization, characterized in that... The method for recycling residual feed heads from plasma rotating electrode atomization is completed according to the following steps:

1. Prepare a cylindrical graphite mold according to the dimensions of the bar billet; Based on the size of the feedstock, manufacture graphite rings; 2. Use sandpaper to roughen the surface of the material head; 3. Sand the bottom conical surface of the sprue until smooth; 4. Use a polishing machine to grind the bottom and bottom sides of the material head to make the contact area between the material head and the raw material powder smooth; 5. Place a graphite pad at the bottom of the cylindrical graphite mold, then place a graphite ring, and place graphite paper on the inner circle of the graphite ring and the part that contacts the material head.

6. Place the feedstock threaded downwards into the graphite ring, and wrap the side of the feedstock with graphite paper to isolate the cylindrical graphite mold and the raw material powder; 7. Fill the cylindrical graphite mold with raw material powder to cover the material head, then cover the raw material powder with graphite paper and press in the graphite gasket.

8. Insert the pressure head into the cylindrical graphite mold and place it in a vacuum hot pressing sintering furnace for sintering at high temperature; 9. Remove the threaded bar obtained from the sintering from the cylindrical graphite mold, and use a lathe to turn the bottom and bottom side of the bar head by 2-30 mm until a metallic luster is achieved. This completes the recycling of the residual bar head from the plasma rotating electrode atomization.

2. The method for recycling residual material from plasma rotating electrode atomization according to claim 1, characterized in that... In step one, the inner diameter of the graphite ring is 1-5 mm larger than the inner diameter of the material head thread, the outer diameter of the graphite ring is 0.5-3 mm smaller than the inner diameter of the cylindrical graphite mold, and the height of the graphite ring is 2-5 mm higher than the material head thread.

3. The method for recycling residual material from plasma rotating electrode atomization according to claim 1, characterized in that... The outer diameter of the cylindrical graphite mold mentioned in step one is 50-80 mm.

4. The method for recycling residual material from plasma rotating electrode atomization according to claim 1, characterized in that... In step two, the sandpaper should be selected between 120# and 5000#. In step three, the sandpaper should be selected between 120# and 5000#.

5. The method for recycling residual material from plasma rotating electrode atomization according to claim 1, characterized in that... The polishing disc of the grinding and polishing machine described in step four rotates at a speed of 100–600 r / min.

6. The method for recycling residual material from plasma rotating electrode atomization according to claim 1, characterized in that... The raw materials selected in step six are TA15 titanium alloy, pure Ti, Ti60 titanium alloy, GH3230 nickel-based superalloy, GH3536 nickel-based superalloy, IN718 nickel-based superalloy, IN738 nickel-based superalloy, titanium-based composite material with 0.5-10 vol.% TiB, or titanium-based composite material with 0.5-10 vol.% TiC; the matrix of the titanium-based composite material is TC4 titanium alloy, TA15 titanium alloy, pure Ti, or Ti60 titanium alloy.

7. The method for recycling residual material from plasma rotating electrode atomization according to claim 1, characterized in that... The raw material powder mentioned in step seven is TA15 titanium alloy, pure Ti, Ti60 titanium alloy, GH3230 nickel-based high-temperature alloy, GH3536 nickel-based high-temperature alloy, IN718 nickel-based high-temperature alloy, IN738 nickel-based high-temperature alloy, titanium-based composite material with 0.5-10 vol.% TiB added, or titanium-based composite material with 0.5-10 vol.% TiC added; the matrix of the titanium-based composite material is TC4 titanium alloy, TA15 titanium alloy, pure Ti, or Ti60 titanium alloy.

8. The method for recycling residual material from plasma rotating electrode atomization according to claim 1, characterized in that... The parameters for sintering at high temperature in step eight are: sintering temperature of 1200-1400℃ and sintering time of 1-4h.

9. The method for recycling residual material from plasma rotating electrode atomization according to claim 8, characterized in that... The parameters for sintering at high temperature in step eight are: sintering temperature of 1300℃ and sintering time of 1h.

10. The method for recycling residual material from plasma rotating electrode atomization according to claim 1, characterized in that... In step nine, turn the bottom of the workpiece head by 2-10mm and the bottom side by 2-10mm.

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