molybdenum-lined crucible

Abstract

A crucible for preparing ceramic particles from metal oxide gel particles, the crucible comprising: a tubular graphite shell having an open end, an inner surface, and a seat in the inner surface proximate the open end. A sleeve is lined within the tubular shell inner surface. The sleeve has at least one open end and is made of a metal that is chemically inert to the metal oxide gel particles. A graphite outer cap removably covers the at least one open end of the tubular shell. An inner cap made of a chemically inert metal fits into the seat in the tubular shell inner surface and is pressed into the seat by the outer cap against the open end of the sleeve. The crucible can be used to prepare ceramic particles from uranium oxide gel particles, and the sleeve and inner cap can be made of molybdenum, tungsten, or alloys thereof.

Description

Technical Field

[0001] The various embodiments disclosed herein generally relate to reactors for sintering metal oxide gel particles, such as crucibles for sintering metal oxide gel particles. Background Technology

[0002] In the process of sintering uranium oxide gel particles to produce uranium oxide, uranium carbide, and / or uranium oxycarbide fuel cores, it is crucial that the crucible remain chemically stable with respect to uranium oxides, carbides, and carbon oxides at temperatures up to 1800°C. Previously, crucibles made of graphite, tungsten, or tantalum were used alone or in the presence of a carbon source for sintering uranium oxide gel particles. However, these materials may not be chemically stable for uranium oxide particles. For example, graphite reacts with uranium dioxide particles, creating a UC2 layer on the particle surface. This can also lead to uranium leaching into the inner surface of the graphite crucible.

[0003] Molybdenum exhibits the greatest chemical stability against uranium oxides and carbides at extreme temperatures, making it the preferred material for producing uranium-based ceramic fuel cores. However, molybdenum is heavy, prone to carburization in the presence of graphite, and typically forms strong welds when in contact with graphite at temperatures above 1700°C. Furthermore, the crucible must allow sufficient gas flow to allow reactive processing gases generated during sintering to escape from the crucible while preventing core particles from escaping.

[0004] Therefore, an improved crucible is desired for reactions involving metal oxide gel particles (including uranium oxide gel particles). This crucible should be lightweight, easy to load, chemically and thermally stable to the metal oxide gel particles, and allow sufficient gas flow. Summary of the Invention

[0005] In view of the current need for improved crucibles for sintering metal oxide gel particles, the following is a brief overview of different embodiments. Some simplifications and omissions may exist in the following overview, which are intended to highlight and illustrate some aspects of various exemplary embodiments, but are not intended to limit the scope of the invention. Detailed descriptions of certain embodiments sufficient to allow those skilled in the art to make and use the concepts disclosed herein will be elaborated in later sections.

[0006] The various embodiments disclosed herein relate to a crucible for preparing ceramic particles from metal oxide gel particles, the crucible comprising: a tubular outer shell made of graphite having at least one open end, an inner surface, and a seat in the inner surface adjacent to the at least one open end; and a sleeve lining the inner surface of the tubular outer shell, wherein the sleeve has at least one open end and is made of a metal that is chemically inert relative to the metal oxide gel particles. A graphite outer cap removably covers at least one open end of the tubular outer shell. An inner cap made of a chemically inert metal is configured to fit into the seat in the inner surface of the tubular outer shell. The outer cap is configured to press the inner cap into the seat against the open end of the sleeve.

[0007] The inner and outer lids can be configured to allow gas to escape from the crucible. The inner lid can be configured to allow gas to pass through it, and the outer lid may include an axial hole through it, wherein gas passing through the inner lid can escape through the axial hole of the outer lid. In various embodiments, the inner lid includes at least one hole through it, said at least one hole being less than 50% of the average particle size of the metal oxide gel particle collection in the crucible. The inner lid may include at least one slit through it, said at least one slit having a width less than 50% of the average particle size of the metal oxide gel particles.

[0008] In different embodiments, the crucible may also include a compressible carbon fiber felt, wherein the compressible carbon fiber felt is configured to press against the inner lid by the outer lid.

[0009] The crucible may also include a graphite ring having an outer seat, wherein the outer seat is configured to engage with the edge of the inner lid, and the graphite ring is configured to press against the edge of the inner lid by the outer lid.

[0010] The crucible may include:

[0011] A graphite ring having an outer seat portion configured to engage with an edge of an inner cover; and

[0012] Compressible carbon fiber felt rings

[0013] The compressible carbon fiber felt ring is configured to press against the graphite ring via the outer cap.

[0014] In various embodiments, the crucible is configured to rotate about its axis, wherein the crucible further includes a rotatable drive shaft configured to engage with an outer cover. The rotatable drive shaft may include polygonal ends, and the outer cover may include a polygonal socket configured to engage with the polygonal ends of the rotatable drive shaft. The rotatable drive shaft may include a through-hole therethrough, and the outer cover may include a through-hole therethrough, wherein the through-hole in the rotatable drive shaft and the through-hole in the outer cover are configured to provide channels allowing gas to escape from within the crucible.

[0015] In various embodiments, the crucible is configured to rotate about its axis, and the crucible further includes a rotatable drive shaft configured to engage with an outer cover. The rotatable drive shaft may include a polygonal end and a hemispherical sphere extending from the polygonal end of the rotatable drive shaft. The outer cover may include a recess configured to receive the polygonal end of the rotatable drive shaft, wherein the recess includes an inner hemispherical recess configured to engage with the hemispherical sphere of the rotatable drive shaft; and an outer polygonal recess configured to engage with the polygonal end of the rotatable drive shaft. The rotatable drive shaft may include a through-hole therethrough, and the outer cover may include a through-hole therethrough, wherein the through-hole in the rotatable drive shaft and the through-hole in the outer cover are configured to provide a passage for gas to escape from the crucible.

[0016] The various embodiments disclosed herein relate to crucibles for preparing ceramic uranium-containing particles from uranium oxide gel particles, the crucible comprising a tubular outer shell made of graphite having at least one open end, an inner surface, and a seat in the inner surface near the at least one open end; and a sleeve lining the inner surface of the tubular outer shell, wherein the sleeve has at least one open end. An outer cover removably covers at least one open end of the tubular outer shell. An inner cover may be configured to fit into the seat in the inner surface of the tubular outer shell; the outer cover may be configured to press the inner cover into the seat against the open end of the sleeve. The sleeve and inner cover may be made of molybdenum. The sleeve and inner cover may be made of a molybdenum alloy comprising 0.5% titanium, 0.08% zirconium, 0.02% carbon, or a mixture thereof. Attached Figure Description

[0017] To better understand the different exemplary implementations, refer to the accompanying drawings, in which:

[0018] Figure 1 A crucible for preparing ceramic particles from metal oxide gel particles is shown, with one end sealed by an outer lid and the other end open;

[0019] Figure 2A It shows along Figure 1 Observed in the direction of arrow A Figure 1The cross-section of the crucible;

[0020] Figure 2B It shows Figure 2A Details of the cross-section show the outer and inner covers;

[0021] Figure 3 It shows the use of Figure 1 The tubular shell of the crucible shown;

[0022] Figure 4A It shows along Figure 3 Observed in the direction of arrow D Figure 3 The cross-section of the tubular shell;

[0023] Figure 4B It shows Figure 4A Details of the cross-section;

[0024] Figure 5 It shows the use of Figure 1 The sleeve of the crucible shown;

[0025] Figure 6 It shows along Figure 5 Observed in the direction of arrow C Figure 5 The cross-section of the sleeve;

[0026] Figure 7A and 7B It shows the use of Figure 1 The outer lid of the crucible shown;

[0027] Figure 8A and 8B It shows the use of Figure 1 The crucible shown has a compressible carbon fiber felt ring.

[0028] Figure 9A and 9B It shows the use of Figure 1 The graphite ring of the crucible shown;

[0029] Figures 10A to 10D It shows the use of Figure 1 The first embodiment of the inner lid of the crucible shown;

[0030] Figure 11A and 11B It shows the use of Figure 1 A second embodiment of the inner lid of the crucible shown;

[0031] Figure 12A And 12C shows for use Figure 1 The third embodiment of the inner lid of the crucible shown;

[0032] Figure 13 and 14 The first part of the rotatable drive shaft is shown;

[0033] Figure 15 and 16 The second part of the rotatable drive shaft is shown; and

[0034] Figure 17 It shows Figure 15 The second part of the rotatable drive shaft and Figure 7B The outer cover is joined. Detailed Implementation

[0035] Referring now to the accompanying drawings, wherein like reference numerals denote like parts or steps, a wide range of aspects of different exemplary embodiments are disclosed below.

[0036] Figure 1 A crucible 1 according to this disclosure is shown, the crucible 1 comprising a tubular outer shell 2 made of graphite. The shell has an open end covered by a removable outer cover 3, which is also made of graphite. The other end may be open, or the other end may be closed. If the other end is open, it can be covered by a second removable cover 3. Figure 1 (Not shown in the image) Covered. For example... Figure 2A As shown, the outer cover 3 is screwed onto the thread 5.

[0037] Figure 2A It shows Figure 1 The cross-section of crucible 1 is shown. In this cross-section, each end of the tubular outer shell 2 is open. A seat 4 is machined onto the inner surface of each end of the tubular outer shell 2. A helical thread 5 is machined into the inner surface of each end of the tubular outer shell 2, wherein the helical thread 5 is located between the seat 4 and the edge of the open end of the tubular outer shell 2. A recess 9 is machined into the outer cover 3. The recess 9 is intended to engage with a rotatable shaft, the engagement method of which will be discussed later. The inner surface of the tubular outer shell is lined with a metal sleeve 11.

[0038] The choice of metal for sleeve 11 depends on the properties of the metal oxide gel particles to be sintered in crucible 1, as the metal used for sleeve 11 must be chemically inert to the metal oxide gel particles to be sintered. In different embodiments, the metal oxide gel particles may be uranium oxide gel particles. In this case, the metal used for sleeve 11 may be molybdenum, tungsten, or alloys thereof. A suitable molybdenum alloy contains 0.5% titanium, 0.08% zirconium, 0.02% carbon, or a mixture thereof. A TZM alloy may also be used, which contains 0.5% titanium, 0.08% zirconium, 0.02% carbon, and the balance molybdenum.

[0039] The thickness of the sleeve 11 can be 0.5 mm to 5 mm, 1 mm to 4 mm, or 2 mm to 3 mm. The sleeve 11 can be machined from a solid bar of the desired metal (e.g., a solid bar of molybdenum, tungsten, or a TZM alloy). Alternatively, a sheet of the desired metal can be formed into a cylinder, and the opposite sides of the sheet can be rolled and joined to form a tubular sleeve 11. A layer of the desired metal can be lined inside the housing 2 using a metal foil. The inner surface of the housing 2 can be coated with tungsten or molybdenum using WF6, Mo(CO)6, or other compounds known in the art as metal precursors via chemical vapor deposition. For the purposes of this disclosure, the term "sleeve" should be understood to include tubular sheets or foils, as well as CVD coatings.

[0040] Figure 2B yes Figure 2A A detailed schematic diagram of one end of the cross-section of crucible 1 is shown. Figure 2B As shown, sleeve 11 is lined to the inner surface of the tubular outer shell 2 of crucible 1. Inner cover 6 is composed of two metal plates (outer plate 6a and inner plate 6b). The edge of inner cover 6 is located within the seat portion 4 of outer shell 2. Graphite ring 7 includes a seat portion 13 that engages with the edge of inner cover 6. Graphite ring 7 presses inner cover 6 into seat portion 4 so that it abuts against the edge of sleeve 11. A ring or disc 8 or graphite mesh containing compressible carbon fiber felt abuts against graphite ring 7. Finally, outer cover 3 is screwed onto the open end of outer shell 2, wherein the threaded outer surface 10 of outer cover 3 engages with the helical thread 5 on the inner surface of tubular outer shell 2. Outer cover 3 presses the carbon fiber felt ring or disc 8, graphite ring 7, and inner cover 6 against the end of sleeve 11. When the metal oxide gel particles are placed in crucible 1 and the open end of the outer shell 2 is sealed by the outer cover 3, the metal oxide gel particles only contact the metal sleeve 11 and the inner metal cover 6, and do not contact the graphite outer shell 2 or the graphite outer cover 3. This prevents undesirable reactions between the metal oxide gel particles and graphite.

[0041] The presence of the carbon fiber felt ring or disc 8 is to prevent the thermal expansion of the metal sleeve 11 from damaging the tubular outer casing 2 or the outer cover 3. Without the carbon fiber felt ring or disc 8, the thermal expansion of the sleeve 11 could cause the outer casing 2 or the outer cover 3 to crack or otherwise be damaged, because the sleeve 11 inside the outer casing 2 cannot expand towards the outer cover 3. However, with the carbon fiber felt ring or disc 8 present, it can be compressed when the sleeve 11 expands longitudinally towards the outer cover 3 within the outer casing 2. This alleviates the stress exerted by the expansion of the sleeve 11 on the outer casing 2 and the outer cover 3.

[0042] Figure 3 The graphite tubular shell 2 used in the crucible 1 according to this disclosure is shown. The graphite tubular shell 2 has at least one open end ( Figure 3(Not shown in the image). The graphite tubular shell 2 may have a single open end at one end and a closed end at the other end. The graphite tubular shell 2 may also have two open ends, with one open end at each end of the shell 2.

[0043] Figure 4A A cross-section of the graphite tubular shell 2 is shown, wherein the cross-section is taken along a plane containing the axis of the shell 2, as shown. Figure 3 As indicated by arrow D. Figure 4A The illustrated embodiment of the graphite tubular housing 2 has two open ends. Each end of the tubular housing 2 has a seat 4 machined into the inner surface of each end of the tubular housing 2. A helical thread 5 is machined into the inner surface of each end of the tubular housing 2, wherein the helical thread 5 is located between the seat 4 and the edge of the open end of the tubular housing 2. Figure 4B A detailed view of an open end of the graphite tubular housing 2 is shown, including the seat 4 and the thread 5.

[0044] Figure 5 A tubular sleeve 11 is shown, the outer diameter of which allows the sleeve 11 to slide longitudinally. Figure 3 In the outer shell 2. Figure 6 A cross-section of the tubular sleeve 11 is shown, wherein the cross-section is taken along a plane containing the axis of the sleeve 11, as shown. Figure 5 As indicated by arrow C, sleeve 11 has at least one open end. Sleeve 11 may have a single open end at one end and a closed end at the other. Sleeve 11 may also have two open ends, one at each end, as shown below. Figure 6 As shown. If sleeve 11 has a single open end, it should slide longitudinally into place. Figure 3 In the outer casing 2 shown, the open end of the sleeve 11 is located at the open end of the outer casing 2.

[0045] Figure 7A and Figure 7B It shows the use of Figure 1 The outer cover 3 of the crucible 1 is shown. Figure 7A As shown, the outer cover 3 includes a helical external thread 10 on its outer surface. Figure 7B It is along Figure 7A The cross-section of the outer cover 3 as observed in the direction of arrow F. (See image below.) Figure 7B As shown, the axial recess 9 passes through the center of the outer cover 3. A polygonal outer recess 9a is formed on the outer surface of the outer cover 3; the polygonal outer recess 9a can be triangular, square, pentagonal, or hexagonal. A hole 9c is formed on the inner surface of the outer cover 3; the hole 9c can be cylindrical or polygonal. The hole 9c and the outer recess 9a are in fluid communication with each other directly or through an inner recess 9b. If an inner recess 9b exists, it has a hemispherical surface connecting the hole 9c and the outer recess 9a.

[0046] Figure 8A and Figure 8B It shows the use of Figure 1 The crucible 1 shown has a compressible carbon fiber felt ring or disk 8 or graphite mesh. Figure 8B It is along Figure 8A The cross-section of the felt or net 8 as observed in the direction of arrow H. (e.g.) Figure 8B As shown, the felt, mesh ring, or disk 8 can be a ring with holes 12 passing through it. In different embodiments, the felt, mesh ring, or disk 8 can be a continuous disk without holes 12, as long as the felt, mesh ring, or disk 8 is permeable to gas.

[0047] Figure 9A and Figure 9B It shows the use of Figure 1 The graphite ring 7 of crucible 1 shown. Figure 9B It is along Figure 9A The cross-section of graphite ring 7 as observed in the direction of arrow G. (See image.) Figure 9B As shown, the graphite ring 7 includes a seat 13 located on its inner side and a hole 14 passing through it.

[0048] Figure 10A and Figure 10B It shows the use of Figure 1 The inner lid 6 of the crucible 1 shown. Figure 10B It is along Figure 10A The cross-section of the inner cover 6 as observed in the direction of arrow J. (See image.) Figure 10A and Figure 10B As shown, the inner cover 6 is composed of two metal plates (outer plate 6a and inner plate 6b). Figure 10C As shown, the outer plate 6a includes two large holes 15, symmetrically distributed on opposite sides of the geometric center of the outer plate 6a. Multiple small vapor-permeable openings 16 pass through the outer plate 6a, wherein the openings 16 can be located at the vertices of a regular polygon with an even number of sides. Figure 10C As shown, opening 16 can be located at a vertex of the square. Another opening 16 can be located at the geometric center of the outer plate 6a. The structure of plate 6b is the same as that of plate 6a. Figure 10DAs shown, plates 6a and 6b are assembled such that hole 16 on plate 6a is aligned with hole 16 on plate 6b. Plates 6a and 6b are assembled such that large hole 15 on plate 6a is offset from large hole 15 on plate 6b. If hole 16 is located at a vertex of a square, then large hole 15 on plate 6a is offset by 180° from large hole 15 on plate 6b. If hole 16 is located at a vertex of a regular hexagon, for example, large hole 15 on plate 6a can be offset by 120° from large hole 15 on plate 6b to ensure alignment of hole 16 on plates 6a and 6b. The thickness of plates 6a and 6b is both 0.5 mm to 2.5 mm, or approximately 1.25 mm to 1.75 mm. Plates 6a and 6b are made of molybdenum, tungsten, or their alloys. Plates 6a and 6b can be made of TZM alloy. In different embodiments, the pore 16 is smaller than the average particle size of the metal oxide gel particles to be sintered in the crucible 1, or smaller than 67% or 50% of the average particle size of the metal oxide gel particles. This prevents the particles from escaping from the sealed crucible while allowing steam to escape from the crucible.

[0049] Back Figure 2B By placing the inner surface of the inner cover 6 against the edge of the sleeve 11, each open end of the outer casing 2 is sealed within the seat 4 of the inner surface of the tubular outer casing 2. A graphite ring 7 is placed on the outer surface of the inner cover 6, and the edge of the inner cover 6 is embedded in the seat 13 of the graphite ring 7 (e.g., ...). Figure 9B (As shown). A ring or disc 8 or graphite mesh of compressible carbon fiber felt is placed against the outer surface of the graphite ring 6. The threaded outer surface 10 of the outer cover 3 is screwed onto the end of the tubular housing 2, such that the threaded outer surface 10 engages with the helical thread 5 on the inner surface of the tubular housing 2. The outer cover 3 is screwed onto the housing 2, pressing the ring or disc 8 against the graphite ring 7, and keeping the inner cover 3 tightly against the tubular sleeve 11. If the tubular housing 2 and the sleeve 11 have only one open end, the sleeve 11 can be filled with metal oxide gel particles, and then the open end of the tubular housing 2 and the sleeve 11 can be sealed, as shown. Figure 2B As shown. If the tubular outer shell 2 and the sleeve 11 have two open ends, one of the open ends of the tubular outer shell 2 and the sleeve 11 can be closed, such as... Figure 2B As shown. Then, the sleeve 11 can be filled with metal oxide gel particles, and the other open end of the tubular outer shell 2 and the sleeve 11 can be sealed. After each open end of the tubular outer shell 2 and the sleeve 11 is sealed, the metal oxide gel particles are only exposed on the metal or metal alloy surface of the sleeve 11 and the inner cover 6, without contacting any graphite part of the crucible 1.

[0050] Figure 11A and Figure 11B It shows the use of Figure 1 Another embodiment of the inner lid 6 of the crucible 1 shown. (As shown) Figure 11AAs shown, the inner cover 6 is made of a single metal plate 17. Plate 17 includes a plurality of small vapor-permeable openings 18 extending through it, wherein the openings 18 may be distributed along radial lines extending outward from the geometric center of plate 17, such as... Figure 11A As shown. Alternatively, the openings 18 can be distributed in multiple concentric circles, or the openings 18 can be randomly distributed on the plate 17. The thickness of the plate 17 is 1.5 mm to 4 mm, about 2.5 mm to 3.5 mm, or about 3 mm. The plate 17 is made of molybdenum, tungsten, or a TZM alloy. In different embodiments, the diameter of the holes 18 is smaller than the average particle size of the metal oxide gel particles to be sintered in the crucible 1, or smaller than 67% of the average particle size of the metal oxide gel particles, or smaller than 50% of the average particle size of the metal oxide gel particles, or has a diameter of 0.5 mm to 0.15 mm. This prevents particles from escaping from the sealed crucible while allowing vapor to escape from the crucible.

[0051] Figure 12A and Figure 12B It shows the use of Figure 1 Another embodiment of the inner lid 6 of the crucible 1. For example... Figure 12A As shown, the inner cover 6 is made of a single metal plate 19. The plate 17 includes a plurality of narrow, vapor-permeable slits 20 extending through the plate 17, wherein the slits 20 may be distributed in parallel lines, extending through the plate 19, as shown... Figure 12A As shown. The thickness of plate 19 is 1.5 mm to 4 mm, approximately 2.5 mm to 3.5 mm, or approximately 3 mm. Plate 19 is made of molybdenum, tungsten, or a TZM alloy. In different embodiments, the width of slit 20 is less than the average particle size of the metal oxide gel particles to be sintered in crucible 1, or less than 67% of the average particle size of the metal oxide gel particles, or less than 50% of the average particle size of the metal oxide gel particles, or the width is 0.5 mm to 0.15 mm. This prevents particles from escaping from the sealed crucible while allowing vapor to escape from the crucible.

[0052] After the crucible is filled with metal oxide gel particles, it is heated to the effective sintering temperature, transforming the metal oxide gel particles into ceramic particles. The inner sleeve 11 and inner cover 6 prevent the metal oxide gel particles and / or ceramic particles from contacting the graphite shell or outer cover 3. The sleeve 11 and inner cover 6, made of molybdenum, tungsten, or TZM alloy, are stable relative to the metal oxide gel particles and / or ceramic particles and do not react with the metal oxide gel at temperatures up to 2000°C. Without the alloy sleeve 11 and inner cover 6, the graphite shell will react with the metal oxide gel, causing the metal oxide gel particles to carbonize.

[0053] In different embodiments, the crucible 1 can be positioned such that the vertical axis is in the horizontal direction, such as... Figure 1As shown. The crucible can rotate about its longitudinal axis, thereby mixing metal oxide gel particles within the tubular sleeve 11 and ensuring uniform heating as the metal oxide gel particles transform into solid ceramic particles. The tubular outer shell can be supported on a rotary bearing (not shown) or a similar support, which allows rotational movement of the outer shell 2. The rotation of the crucible 1 can be driven by a rotating shaft driven by an electric motor (not shown), which engages with the outer cover 9 of the crucible 1.

[0054] Figure 13 and Figure 14 A first portion 21 of the rotating shaft is shown, which may be made of tungsten, molybdenum, or TZM alloy. The first portion 21 includes a tubular shaft 24 having an axial through-hole 24a therethrough. A first end of the shaft 24 includes an enlarged recess 22, the inner surface of which has an internal thread 23. A second end of the shaft 24 includes a recess 26, the inner surface of which has an internal thread 25. The internal thread 25 on the recess 26 is configured to engage with a threaded end of a motor drive shaft. The internal thread 23 on the recess 22 is configured to engage with a second portion 27 of the rotating shaft, such as... Figure 15 As shown.

[0055] Figure 15 and Figure 16 A second portion 27 of the rotating shaft is shown, which may be made of graphite, tungsten, molybdenum, or a TZM alloy. The second portion 27 includes a shaft 28. A first end of the shaft 28 includes an external thread 32 located on its outer surface. A second end of the shaft 28 includes a polygonal protrusion 29 that can be milled into the outer surface of the shaft 28. Figure 15 As shown, the polygonal protrusion 29 can be a square. Alternatively, the polygonal protrusion 29 can be a triangle, pentagon, or hexagon. The second end of the shaft 28 also includes a hemispherical protrusion 30, which can be milled into the outer surface of the polygonal protrusion 29. The external thread 32 is configured to engage with the internal thread 23 of the recess 22 on the first portion 21 of the rotating shaft. The protrusions 29 and 30 on the second portion 27 of the rotating shaft are configured to engage with the outer cover 3 of the crucible 1, as shown. Figure 17 As shown. The second part 27 of the rotating shaft includes an axial through-hole 31 passing through it. When the external thread 32 engages with the internal thread 23 on the recess 22, the axial through-holes 31 and 24a are in fluid communication with each other.

[0056] If necessary, the first part 21 and the second part 27 of the rotating shaft can be made into a single component, which can be made of graphite, tungsten, molybdenum or TZM alloy.

[0057] refer to Figure 17An axial recess 9 passes through the center of the outer cover 3 of the crucible 1. A polygonal outer recess 9a is formed on the outer surface of the outer cover 3. The polygonal outer recess 9a is configured to engage with the polygonal protrusion 29 of the rotating shaft portion 27. An inner recess 9b has a hemispherical surface and is configured to engage with the hemispherical protrusion 30 of the rotating shaft portion 27. A hole 9c is formed on the inner surface of the outer cover 3. The hole 9c is in fluid communication with the axial through hole 31 of the rotating shaft portion 27, providing a channel for gas to escape from the crucible 1. The rotation of the rotating shaft causes the polygonal protrusion 29 to transmit torque to the polygonal outer recess 9a of the outer cover 3, thereby driving the crucible 1 to rotate about its longitudinal axis.

[0058] While various exemplary embodiments have been described in detail with reference to specific exemplary aspects, it should be understood that the invention may have other embodiments, and its details may be modified in various obvious ways. It will be apparent to those skilled in the art that variations and modifications can be made while maintaining the spirit and scope of the invention. Therefore, the foregoing disclosure, description, and drawings are for illustrative purposes only and are not intended to limit the invention in any way, which is defined only by the claims.

Claims

1. A crucible for preparing ceramic particles from metal oxide gel particles, the crucible comprising: A tubular shell made of graphite, the tubular shell having at least one open end, an inner surface, and a seat in the inner surface near at least one open end; A sleeve, which is lined on the inner surface of the tubular housing, wherein the sleeve has at least one open end and is made of a metal that is chemically inert relative to the metal oxide gel particles; A graphite outer cover, which removably covers at least one open end of the tubular housing; and Inner cover, the inner cover being made of the chemically inert metal; in: The inner cover is configured to fit a seat in the inner surface of the tubular outer shell; The outer cover is configured to press the inner cover into the seat so that it abuts against the open end of the sleeve.

2. The crucible of claim 1, wherein the inner lid and the outer lid are configured to allow gas to escape from the crucible.

3. The crucible according to claim 2, wherein: The inner cover is configured to allow gas to pass through it; The outer cover includes an axial hole passing through it.

4. The crucible of claim 3, wherein the inner cover includes at least one hole therethrough, the at least one hole being less than 50% of the average particle size of the metal oxide gel particles.

5. The crucible of claim 3, wherein the inner cover includes at least one slit passing through it, the width of the at least one slit being less than 50% of the average particle size of the metal oxide gel particles.

6. The crucible of claim 1, further comprising a compressible carbon fiber felt, wherein the compressible carbon fiber felt is configured to press against the inner cover by the outer cover.

7. The crucible of claim 1, further comprising a graphite ring having an outer seat, wherein the outer seat is configured to engage with an edge of the inner cover, and the graphite ring is configured to press against the edge of the inner cover by the outer cover.

8. The crucible of claim 7, further comprising a compressible carbon fiber felt ring, wherein the compressible carbon fiber felt ring is configured to press against the graphite ring by an outer cap.

9. The crucible according to claim 1, wherein: The crucible is configured to rotate about its axis; The crucible also includes a rotatable drive shaft; The rotatable drive shaft is configured to engage with the outer cover.

10. The crucible according to claim 9, wherein: The rotatable drive shaft includes polygonal ends; The outer cover includes a polygonal recess configured to engage with the polygonal end of the rotatable drive shaft.

11. The crucible according to claim 10, wherein: The rotatable drive shaft includes a through-hole therethrough; The outer cover includes a hole through it; The through-hole in the rotatable drive shaft and the hole in the outer cover are configured to provide channels for gas to escape from the crucible.

12. The crucible according to claim 9, wherein: The rotatable drive shaft includes a polygonal end and a hemispherical sphere extending from the polygonal end of the rotatable drive shaft; The outer cover includes a recess configured to receive an end of the rotatable drive shaft, wherein the recess includes: An inner hemispherical recess, the inner hemispherical recess being configured to engage with the hemispherical body of the rotatable drive shaft; and An outer polygonal recess is configured to engage with the polygonal end of the rotatable drive shaft.

13. The crucible according to claim 12, wherein: The rotatable drive shaft includes a through-hole therethrough; The outer cover includes a hole through it; The through-hole in the rotatable drive shaft and the hole in the outer cover are configured to provide a passage for gas to escape from the crucible.

14. A crucible for forming ceramic uranium-containing particles from uranium oxide gel particles, the crucible comprising: A tubular shell made of graphite, the tubular shell having at least one open end, an inner surface, and a seat in the inner surface near at least one open end; A sleeve, the sleeve being lined on the inner surface of the tubular housing, wherein the sleeve has at least one open end and is made of molybdenum or an alloy thereof; An outer cover that removably covers at least one open end of the tubular housing; and Inner cover, said inner cover being made of molybdenum or an alloy thereof; in: The inner cover is configured to fit a seat in the inner surface of the tubular outer shell; The outer cover is configured to press the inner cover into the seat so that it abuts against the open end of the sleeve.

15. The crucible of claim 14, wherein the sleeve and the inner cover are made of molybdenum, tungsten, or an alloy thereof.

16. The crucible of claim 14, wherein the sleeve and the inner cover are made of a molybdenum alloy comprising 0.5% titanium, 0.08% zirconium, and 0.02% carbon.

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