Heat treatment member and method of manufacturing the same

Abstract

To provide a member for heat treatment capable of suppressing metal contamination to an object to be treated and low in production cost, and to provide a method for producing the same.SOLUTION: The heat treatment member 1 comes into contact with an object 9 to be heat-treated in a heat treatment furnace. A heat treatment member 1 includes a ceramic substrate 2, and a carbon layer 3 disposed on a surface of the substrate 2 and in contact with an object 9 to be treated.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a heat treatment member that comes into contact with a workpiece, such as a battery material, and a method for manufacturing the same. [Background technology]

[0002] Atmospheric heat treatment furnaces are used for heat treatment of battery materials. Some battery materials are sensitive to metal contamination. In this case, the battery materials are contained in non-metallic saggers and transported through the atmosphere heat treatment furnace. For example, Patent Document 1 discloses saggers made of carbon (graphite). Using carbon saggers can suppress metal contamination of the battery materials. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7343243 Summary of the Invention [Problem to be solved by the invention]

[0004] However, carbon saggers are expensive. Therefore, an object of the present disclosure is to provide a heat treatment member that can suppress metal contamination of the workpiece and has low manufacturing costs, and a manufacturing method thereof. [Means for solving the problem]

[0005] (1) In order to solve the above problems, the heat treatment member of the present disclosure is a heat treatment member that comes into contact with a workpiece that is heat-treated in a heat treatment furnace, and is characterized by comprising a ceramic substrate and a carbon layer that is disposed on the surface of the substrate and comes into contact with the workpiece.

[0006] Here, the form in which the carbon layer is "disposed on the surface of the substrate" includes, for example, a form in which the carbon layer is laminated on the surface of the substrate (a form in which the carbon layer and the substrate are independent of each other) and a form in which the carbon layer is formed by carbon diffusing and penetrating into the surface of the substrate (a form in which the carbon layer and the substrate overlap).

[0007] The heat treatment member of this configuration includes a ceramic substrate and a carbon layer that contacts the workpiece. It is mainly the carbon layer that contacts the workpiece. This makes it possible to suppress metal contamination of the workpiece. The substrate is also made of ceramic. Therefore, even if at least a portion of the carbon layer peels off from the substrate and the substrate mainly comes into contact with the workpiece, it is possible to suppress metal contamination of the workpiece. In this way, this configuration ensures contamination suppression functionality equivalent to that of a heat treatment member made of carbon.

[0008] Furthermore, the substrate is made of ceramic, not carbon material. This allows for reduced manufacturing costs compared to when the entire heat treatment member is made of carbon. Furthermore, the substrate is made of ceramic, which is harder than carbon. This allows for increased durability of the heat treatment member.

[0009] (1-1) In the configuration of (1) above, the heat treatment furnace preferably has a heat treatment chamber for subjecting the workpiece to heat treatment, the base is a heat insulating material whose surface is exposed to the heat treatment chamber, and the carbon layer is exposed to the heat treatment chamber. According to this configuration, the heat treatment chamber can be divided using a heat treatment member (a heat insulating material having a carbon layer).

[0010] (2) In any of the above configurations, the substrate is preferably a carrier for carrying the workpiece. Here, "carrying" includes carrying the workpiece within a heat treatment furnace, carrying the workpiece into the heat treatment furnace from outside the furnace, and carrying the workpiece out of the heat treatment furnace from inside the furnace to outside the furnace. According to this configuration, the workpiece can be carried using a heat treatment member (carrying tool having a carbon layer).

[0011] (3) In the configuration of (2) above, the carrier is preferably a sagger in which the material to be treated is housed, and the carbon layer is preferably disposed on the inner surface of the sagger. This configuration can reduce manufacturing costs compared to saggers made of carbon material while maintaining performance equivalent to that of a sagger made of carbon. Furthermore, it can be made more durable than a sagger made of carbon material.

[0012] (4) In any of the above configurations, the ceramic is preferably mullite or alumina, which can reduce the manufacturing cost of the substrate compared to when the substrate is made of magnesia or the like.

[0013] (5) In any of the above configurations, the carbon layer is preferably a carburized layer formed by carburizing treatment. According to this configuration, a carbon layer (carburized layer) can be easily formed on the surface of the substrate by carburizing treatment.

[0014] (5-1) In the above configuration (5), it is preferable that the carbon concentration of the carburized layer decreases from the surface of the base toward the inside. This configuration makes it possible to increase the carbon concentration near the surface of the base, i.e., the surface of the carburized layer.

[0015] (6) In any of the above configurations, the object to be treated is preferably a battery material. With this configuration, metal contamination of the battery material can be suppressed compared to when the heat treatment member is made of metal.

[0016] (7) In order to solve the above problems, the manufacturing method of a member for heat treatment disclosed herein is a manufacturing method of a member for heat treatment having the configuration described in (5) above, characterized by comprising: a heating step of heating the base; and a carburizing step of supplying a carburizing gas containing carbon to the surface of the heated base, thermally decomposing the carburizing gas using the temperature of the base, and allowing the carbon generated by the thermal decomposition to diffuse and penetrate into the surface of the base, thereby forming the carburized layer.

[0017] According to this configuration, a carbon layer (carburized layer) can be easily formed on the surface of the substrate by carburizing treatment. In addition, the temperature of the heated substrate itself can be used to thermally decompose the carburizing gas, forming a carburized layer on the surface of the substrate.

[0018] (8) In the configuration of (7) above, the temperature reached by the base in the heating step is the carburizing temperature, and the time required for the carburizing step is the carburizing time. It is preferable that the carburizing temperature is 400°C or higher and 1000°C or lower, and the carburizing time is 20 minutes or higher and 120 minutes or lower.

[0019] This configuration prevents the carburized layer from becoming excessively thin compared to when the carburizing time is less than 20 minutes. Furthermore, this configuration prevents the carburized layer from becoming excessively thick compared to when the carburizing time exceeds 120 minutes. Furthermore, this configuration ensures the thermal decomposition of the carburizing gas compared to when the carburizing temperature is less than 400°C. Furthermore, this configuration prevents the carburized layer from peeling compared to when the carburizing temperature exceeds 1000°C. Thus, this configuration allows a good carburized layer to be formed on the surface of the substrate.

[0020] (8-1) In the above configuration (8), it is preferable that the carburizing temperature be 800°C or higher and 950°C or lower. With this configuration, the carburizing gas can be thermally decomposed more reliably than when the carburizing temperature is lower than 800°C. Also, peeling of the carburized layer can be more reliably suppressed than when the carburizing temperature is higher than 950°C.

[0021] (9) In any of the above (7) to (8-1), it is preferable that the carburizing gas contains one or more gases selected from propane gas, butane gas, acetylene gas, and natural gas, and that the amount of the carburizing gas supplied in the carburizing step is 0.33% or more, with the mass of the base being 100%.

[0022] This configuration allows for the formation of a carburized layer of sufficient thickness on the surface of the substrate, compared to when the amount of carburizing gas supplied is less than 0.33% of the substrate's mass (100%). If the amount of carburizing gas supplied is too much, the excess can be burned off.

[0023] (10) In any of the above configurations (7) to (9), the base is a sagger having an opening and accommodating the workpiece, the carburized layer is disposed on the inner surface of the sagger, and the sagger is preferably oriented so that the opening is not sealed during the carburizing process. This configuration allows carburizing gas to be introduced into the sagger through the opening, ensuring the formation of a carburized layer on the inner surface of the sagger. [Effects of the Invention]

[0024] The heat treatment member and the manufacturing method thereof according to the present disclosure can suppress metal contamination of the workpiece and reduce the manufacturing cost of the heat treatment member. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a vertical cross-sectional view of a member for heat treatment according to a first embodiment. [Figure 2] FIG. 2 is an enlarged view of the area within the frame II in FIG. [Figure 3] FIG. 3 is a vertical cross-sectional view of a carburizing furnace used in the manufacture of the member for heat treatment. [Figure 4] FIG. 4 is a partial enlarged view of the heating chamber of FIG. [Figure 5] FIG. 5 is a vertical cross-sectional view of a heating chamber of a carburizing furnace used in the manufacture of a member for heat treatment according to the second embodiment. [Figure 6] FIG. 6 is a vertical cross-sectional view of a heating chamber of a carburizing furnace used in the manufacture of a member for heat treatment according to the third embodiment. [Figure 7] FIG. 7 is a vertical cross-sectional view of a rotary kiln equipped with a heat treatment member according to the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the member for heat treatment and the method for manufacturing the same according to the present disclosure will be described.

[0027] First Embodiment Fig. 1 shows a vertical cross-sectional view of a heat treatment component of this embodiment. Fig. 2 shows an enlarged view of the area within frame II in Fig. 1. Fig. 3 shows a vertical cross-sectional view of a carburizing furnace used in manufacturing the heat treatment component. Fig. 4 shows a partial enlarged view of the heating chamber in Fig. 3.

[0028] (Heat treatment material 1) First, a heat treatment member 1 of this embodiment will be described. As shown in Figures 1 and 2, the heat treatment member 1 includes a sagger 2 and a carburized layer 3. The heat treatment member 1 is used when transporting a workpiece 9 in a heat treatment furnace (for example, a tunnel kiln, a roller hearth kiln, etc.).

[0029] The object to be treated 9 is a battery material (more specifically, a battery material (raw material of the battery material) before heat treatment) that is susceptible to metal contamination. The object to be treated 9 is subjected to a predetermined heat treatment in a heat treatment furnace (not shown). During the heat treatment, the object to be treated 9 is accommodated inside the heat treatment member 1.

[0030] The sagger 2 is made of mullite and has a bottomed box shape (rectangular box shape). The sagger 2 has an opening 20 facing upward (facing upward when the workpiece 9 is transported). The carburized layer 3 is made of a carbon material and is disposed on the inner surface (surface) 21 of the sagger 2. Specifically, the carburized layer 3 is formed on the inner surface 21 of the sagger 2 by carbon diffusing and penetrating into the inner surface 21. The carburized layer 3 is formed from the inner surface 21 to a predetermined depth of the sagger 2 (e.g., 3 μm from the inner surface 21). In other words, the carburized layer 3 and the sagger 2 overlap over a certain depth range from the inner surface 21. This depth is the thickness of the carburized layer 3. The surface of the carburized layer 3 is flush with the inner surface 21. The surface of the carburized layer 3 is in contact with the workpiece 9.

[0031] (Carburizing furnace 4) Next, the carburizing furnace 4 used in the manufacture of the heat treatment component of this embodiment will be described. As shown in Fig. 3, the carburizing furnace 4 is used to carburize the sagger 2. The carburizing furnace 4 includes a housing 40, a plurality of heaters (heating units) 41, a pair of left and right hearths 42, a tray 43, a plurality of thermocouples 44, a heating chamber 45, a carburizing gas supply line 46, and a nitrogen gas supply line 47.

[0032] The housing 40 includes an outer shell 400, a heat insulating material 401, and a plurality of gas vent holes 402. The outer shell 400 is made of punched metal and has a box shape. The heat insulating material 401 is made of ceramic fiber. The heat insulating material 401 is laminated on the inner surface of the outer shell 400. The heating chamber 45 is defined inside the heat insulating material 401. The plurality of gas vent holes 402 are drilled in the bottom wall of the housing 40.

[0033] The heaters 41 each penetrate the housing 40 in the vertical direction. The heaters 41 are so-called electric heaters that generate heat when electricity is applied. The heaters 41 are exposed to the heating chamber 45.

[0034] A pair of left and right hearths 42 are arranged on the bottom wall of the housing 40. The hearths 42 are fixed to the bottom wall of the housing 40. A tray 43 is placed on the pair of left and right hearths 42. As shown in FIGS. 3 and 4, a plurality of saggers 2 are placed on the tray 43. That is, the plurality of saggers 2 are carried into and carried out of the heating chamber 45 while being placed on the tray 43. A plurality of thermocouples 44 are arranged above the heating chamber 45. A carburizing gas supply line 46 and a nitrogen gas supply line 47 are each connected to the heating chamber 45.

[0035] (Method of manufacturing member for heat treatment 1) Next, a method for manufacturing the member for heat treatment 1 of this embodiment will be described. The method for manufacturing the member for heat treatment 1 includes a heating step and a carburizing step.

[0036] In the heating process, first, a plurality of saggers 2 are loaded onto a tray 43 outside the carburizing furnace 4. Specifically, as shown in FIG. 4, a plurality of saggers 2 are stacked vertically on the upper surface of the tray 43. At this time, the saggers 2 are arranged sideways (with the openings 20 facing left and right (the direction intersecting the stacking direction of the plurality of saggers 2)). The openings 20 are open to the outside (the outside of the saggers 2). The openings 20 are not sealed.

[0037] Next, as shown in Fig. 3, the tray 43 is carried into the furnace (heating chamber 45) of the carburizing furnace 4 and placed on the upper surfaces of the pair of left and right hearths 42. Subsequently, the saggers 2 are heated to a predetermined carburizing temperature (a temperature in the range of 800°C to 950°C) by a plurality of heaters 41. The temperature in the heating chamber 45 is detected by a thermocouple 44.

[0038] During the carburizing process, carburizing gas (propane gas (hydrocarbon gas)) is supplied to the heating chamber 45 via the carburizing gas supply line 46. The amount of carburizing gas supplied is set to be at least 0.33%, with the mass of the sagger 2 being 100%. The supply of carburizing gas expels air from the heating chamber 45. As shown by the arrows in Figures 3 and 4, the carburizing gas diffuses within the heating chamber 45 and enters the sagger 2 through the opening 20. The carburizing gas comes into contact with the inner surface 21 of the sagger 2. The temperature of the sagger 2 has been heated to a predetermined carburizing temperature in the previous process (heating process). Therefore, the carburizing gas that comes into contact with the inner surface 21 is thermally decomposed. Carbon is generated by the thermal decomposition. The carburizing gas is burned by a burner (not shown) at the outlet of the gas vent 402 and released outside the furnace.

[0039] After a predetermined time has elapsed, the supply of carburizing gas is stopped. Then, the nitrogen gas supply line 47 and the gas vent hole 402 are sealed (i.e., the heating chamber 45 is airtight), and the predetermined time is maintained. During this period, carbon generated by pyrolysis diffuses from the inner surface 21 of the sagger 2 to the interior. In this way, the carburizing treatment is performed on the inner surface 21 of the sagger 2 in the heating chamber 45. The carburizing time (the time required for this step) is within the range of 20 minutes to 120 minutes. A carburized layer 3 is formed on the inner surface 21 by this step. In other words, the heat treatment component 1 shown in FIG. 1 is completed.

[0040] Thereafter, the power supply to the heater 41 is cut off, and nitrogen gas (cooling gas) is supplied to the heating chamber 45 via the nitrogen gas supply line 47. That is, the members for heat treatment 1 are cooled (forced cooled) to room temperature (300°C or less). Then, the trays 43 containing the members for heat treatment 1 are carried out of the furnace.

[0041] (Action and effect) Next, the effects of the member for heat treatment and the method for manufacturing the same according to this embodiment will be described.

[0042] (Effects of heat treatment components) As shown in FIGS. 1 and 2, the heat treatment member 1 includes a sagger 2 and a carburized layer (carbon layer) 3. The carburized layer 3 is in contact with the workpiece 9. This makes it possible to suppress metal contamination of the workpiece 9. The sagger 2 is made of mullite, i.e., ceramic. This makes it possible to suppress metal contamination of the workpiece 9 even if the carburized layer 3 peels off from the sagger 2 and the surface (bare surface) of the sagger 2 comes into contact with the workpiece 9. In this way, the heat treatment member 1 of this embodiment can ensure contamination suppression functionality equivalent to that of a heat treatment member 1 made of a carbon material.

[0043] Furthermore, the sagger 2 is made of ceramic, not carbon material. This allows for reduced manufacturing costs compared to when the entire heat treatment member 1 is made of carbon material. The sagger 2 is also made of ceramic, which is harder than carbon material. This allows for reduced brittleness of the heat treatment member 1. This in turn allows for increased durability of the heat treatment member 1. The sagger 2 is made of mullite. This allows for reduced manufacturing costs of the sagger 2 compared to when the sagger 2 is made of magnesia or the like.

[0044] 2, the carbon concentration of the carburized layer 3 decreases from the inner surface (surface) 21 of the sagger 2 toward the interior. In other words, it increases from the interior of the sagger 2 toward the inner surface 21. This makes it possible to maximize the carbon concentration near the inner surface 21 of the sagger 2, i.e., the surface of the carburized layer 3, throughout the entire depth direction of the carburized layer 3.

[0045] 1 and 2 is a battery material, and therefore, compared to when the heat treatment member 1 is made of metal, metal contamination of the battery material can be suppressed.

[0046] (Effects of the method for manufacturing a member for heat treatment) The method for manufacturing a member for heat treatment 1 of this embodiment includes a heating step and a carburizing step. As shown in Figures 3 and 4, the method for manufacturing a member for heat treatment 1 of this embodiment makes it possible to easily form a carburized layer 3 on the inner surface 21 of the sagger 2 by carburizing. In addition, the temperature of the heated sagger 2 itself can be used to thermally decompose the carburizing gas, thereby forming the carburized layer 3 on the inner surface 21 of the sagger 2.

[0047] The carburizing temperature (the temperature reached by the sagger 2 in the heating step) is set to fall within the range of 400°C or higher and 1000°C or lower. This ensures that the carburizing gas can be thermally decomposed more reliably than when the carburizing temperature is lower than 400°C. Furthermore, this prevents the carburized layer 3 from peeling off from the inner surface 21 more reliably than when the carburizing temperature exceeds 1000°C. Furthermore, the carburizing temperature is set to fall within the range of 800°C or higher and 950°C or lower. This ensures that the carburizing gas can be thermally decomposed more reliably than when the carburizing temperature is lower than 800°C. Furthermore, this prevents the carburized layer 3 from peeling off from the inner surface 21 more reliably than when the carburizing temperature exceeds 950°C.

[0048] The carburizing time (the time required for the carburizing process) is set to fall within the range of 20 to 120 minutes. This prevents the thickness of the carburized layer 3 (depth from the inner surface 21) from becoming excessively thin compared to when the carburizing time is less than 20 minutes. Also, it prevents the thickness of the carburized layer 3 from becoming excessively thick compared to when the carburizing time exceeds 120 minutes.

[0049] The amount of carburizing gas supplied in the carburizing process is set to be 0.33% or more, with the mass of the sagger 2 taken as 100%. Therefore, a carburized layer 3 of sufficient thickness can be formed on the inner surface 21, compared to when the amount of carburizing gas supplied is less than 0.33%.

[0050] As shown in Figures 3 and 4, in the carburizing process, the sagger 2 is placed sideways. The opening 20 is open to the outside (outside of the sagger 2). The opening 20 is not sealed. Therefore, as shown by the arrows in Figures 3 and 4, the carburizing gas can be introduced into the inside of the sagger 2 through the opening 20. Therefore, the carburized layer 3 can be reliably formed on the inner surface 21.

[0051] Second Embodiment The difference between the heat treatment member and the manufacturing method thereof of this embodiment and the heat treatment member and the manufacturing method thereof of the first embodiment is that a recess is formed at the opening of the sagger, and that multiple saggers are arranged vertically during the manufacturing of the heat treatment member. Here, the differences will be mainly described.

[0052] Figure 5 shows a vertical cross-sectional view of the heating chamber of a carburizing furnace used in the manufacture of a heat treatment component of this embodiment. The same reference numerals are used to denote portions corresponding to those in Figure 4. As shown in Figure 5, the opening 20 of the sagger 2 is provided with four recesses 22 that are recessed from the rim of the opening 20 toward the bottom. The four recesses 22 are located on the four sides of the opening 20.

[0053] In the manufacturing method of a heat treatment member (heating step, carburizing step), multiple saggers 2 are stacked vertically on the upper surface of a tray 43. In this embodiment, the saggers 2 are arranged vertically (with the openings 20 facing vertically (the stacking direction of multiple saggers 2)). The opening 20 of any sagger 2 is sealed by the bottom wall of another sagger 2 adjacent to it above. However, a recess 22 is provided in the opening 20. Therefore, in the carburizing step, carburizing gas can be introduced into the sagger 2 through the recess 22. In other words, a carburized layer 3 can be formed on the inner surface 21.

[0054] The heat treatment member and manufacturing method thereof of this embodiment and the heat treatment member and manufacturing method thereof of the first embodiment have the same effects as those of the first embodiment, in that they share the same configuration. According to the manufacturing method of the heat treatment member of this embodiment, the plurality of saggers 2 are arranged vertically when stacked (packed) on the tray 43. Therefore, the carburized layer 3 can be formed not only on the inner surface 21 of the saggers 2 but also on the outer surface.

[0055] Third Embodiment The difference between the member for heat treatment and the manufacturing method thereof of this embodiment and the member for heat treatment and the manufacturing method thereof of the first embodiment is that the saggers that are the subject of the manufacturing method for the member for heat treatment are used products. Here, the difference will be mainly described.

[0056] Fig. 6 shows a vertical cross-sectional view of the heating chamber of a carburizing furnace used in the manufacture of a member for heat treatment according to this embodiment. The same reference numerals are used to denote parts corresponding to those in Figs. 1 and 4. As shown in Fig. 6, the sagger 2 used in the method for manufacturing a member for heat treatment according to this embodiment is not a new one (a sagger 2 on which a carburized layer 3 has never been formed), but a used one (a sagger 2 on which a carburized layer 3 has been formed at least once).

[0057] At least a part (all or a part) of the carburized layer 3 of the heat treatment member 1 used to transport the workpiece may peel off from the inner surface 21 of the sagger 2. Alternatively, the thickness of at least a part of the carburized layer 3 may have become thin. In such cases, the used heat treatment member 1 is subjected to the method for manufacturing a heat treatment member of this embodiment (the method for regenerating a heat treatment member), thereby repairing and regenerating the carburized layer 3.

[0058] The heat treatment member and its manufacturing method of this embodiment and the heat treatment member and its manufacturing method of the first embodiment have the same effects as those of the first embodiment, in terms of the common configuration. According to the manufacturing method of the heat treatment member of this embodiment, the used heat treatment member 1 can be reused. Therefore, the manufacturing cost of the heat treatment member 1 can be reduced.

[0059] The sagger 2 is made of ceramic, while the carburized layer 3 is made of a carbon material. Furthermore, the sagger 2 is not in contact with the workpiece, while the carburized layer 3 is in contact with the workpiece. For this reason, the sagger 2 is more durable than the carburized layer 3. Therefore, the sagger 2 essentially needs to be replaced less frequently than the carburized layer 3. Therefore, if the entire heat treatment component 1 were replaced based on the deterioration of the carburized layer 3 (replacing not only the carburized layer 3 but also the sagger 2), not only would the deteriorated carburized layer 3 be discarded, but also the sagger 2, which is still usable.

[0060] In this regard, according to the manufacturing method of a member for heat treatment (method for recycling a member for heat treatment) of this embodiment, it is possible to reuse a sagger 2 that is still usable to manufacture a member for heat treatment 1 (recycled product). This reduces the manufacturing cost of the member for heat treatment 1. It also reduces the running cost of the heat treatment furnace when subjecting the workpiece to heat treatment, and ultimately the processing cost of the workpiece. Note that the method for recycling a member for heat treatment of this embodiment can be carried out independently of the member for heat treatment and its manufacturing method of the present disclosure.

[0061] <Fourth embodiment> The difference between the heat treatment member and the manufacturing method thereof of this embodiment and the heat treatment member and the manufacturing method thereof of the first embodiment is that the heat treatment member is embodied as a rotary cylinder part of a rotary kiln. Here, the difference will be mainly described.

[0062] FIG. 7 shows a vertical cross-sectional view (cross-sectional view perpendicular to the axis) of a rotary kiln equipped with a heat treatment member according to this embodiment. The same reference numerals are used to denote parts corresponding to those in FIG. 1. As shown in FIG. 7, the rotary kiln 5 includes a pair of front and rear tires 50, a pair of front and rear rotary cylinder support members 51, a rotary cylinder 52, and a base 53. The rotary kiln 5 falls within the concept of a "heat treatment furnace" (atmospheric heat treatment furnace) of the present disclosure. The rotary cylinder 52 falls within the concept of a "heat treatment member" of the present disclosure.

[0063] A pair of front and rear rotating barrel support parts 51 are arranged on the upper surface of the stand 53. The rotating barrel support part 51 is equipped with a pair of left and right rollers 510. Note that Fig. 7 shows the rotating barrel support part 51 on the rear side of the rotating barrel part 52. A similar rotating barrel support part (not shown) is also arranged on the front side of the rotating barrel part 52.

[0064] The rotating cylinder 52 has a cylindrical shape extending in the front-rear direction. The rotating cylinder 52 is supported by a pair of front and rear rotating cylinder support parts 51 so as to be rotatable about its own axis via a pair of front and rear tires 50 (described later). The rotating cylinder 52 includes an outer shell 520, a heat insulating material 521, and a carburized layer 3. The heat insulating material 521 is included in the concept of "base" in this disclosure.

[0065] The outer shell 520 is made of steel and has a cylindrical shape extending in the front-to-rear direction. The heat insulating material 521 is made of ceramic and has a cylindrical shape extending in the front-to-rear direction. The heat insulating material 521 is laminated on the radially inner side of the outer shell 520. A heat treatment chamber 54 is defined radially inside the heat insulating material 521. The workpiece 9 is accommodated in the heat treatment chamber 54. In the heat treatment chamber 54, the workpiece 9 is subjected to a predetermined heat treatment in a predetermined atmosphere. An inner surface (surface) 521a of the heat insulating material 521 is exposed to the heat treatment chamber 54.

[0066] The carburized layer 3 is made of a carbon material and is disposed on the inner surface 521a of the heat insulating material 521. Specifically, the carburized layer 3 is formed on the inner surface 521a of the heat insulating material 521 by carbon diffusing and penetrating into the inner surface 521a of the heat insulating material 521. The carburized layer 3 is formed from the inner surface 521a to a predetermined depth range of the heat insulating material 521. In other words, the carburized layer 3 and the heat insulating material 521 overlap over a certain depth range from the inner surface 521a. The surface of the carburized layer 3 is in contact with the workpiece 9.

[0067] A pair of front and rear tires 50 are mounted on the outer circumferential surface of the rotating cylinder portion 52. Note that Figure 7 shows the tire 50 on the rear side of the rotating cylinder portion 52. A similar tire (not shown) is also arranged on the front side of the rotating cylinder portion 52. The pair of front and rear tires 50 are supported rotatably around the axis of the rotating cylinder portion 52 by a pair of front and rear rotating cylinder support portions 51.

[0068] When heat treatment is performed on the workpiece 9, the pair of front and rear rotating cylinder support members 51 are driven to rotate the pair of front and rear tires 50, i.e., the rotating cylinder 52. The rotating cylinder 52 is heated from the radial outside of the rotating cylinder 52 by a heating unit (not shown), such as a heater (e.g., heater 41 shown in FIG. 3). In the heat treatment chamber 54, the workpiece 9 is heated by the heating unit. Furthermore, the workpiece 9 oscillates within the heat treatment chamber 54 as the rotating cylinder 52 rotates.

[0069] The heat treatment member and manufacturing method thereof of this embodiment and the heat treatment member and manufacturing method thereof of the first embodiment have similar effects with respect to the common configuration parts. According to the rotatable tube 52 of this embodiment, the heat treatment chamber 54 can be partitioned by utilizing the rotatable tube 52 (thermal insulating material 521 having the carburized layer 3). As in this embodiment, the base (thermal insulating material 521) of the heat treatment member (rotatable tube 52) does not have to be a carrier (such as a sagger 2).

[0070] <Other> The embodiments of the member for heat treatment and the manufacturing method thereof according to the present disclosure have been described above. However, the embodiments are not particularly limited to the above-described embodiments. Various modifications and improvements that can be made by those skilled in the art are also possible.

[0071] The type of ceramic forming the substrate is not particularly limited. It may be silicon nitride, aluminum nitride, silicon carbide, mullite, alumina, magnesia, zirconia, glass, pottery, porcelain, refractory, cement, or the like. The type of substrate is not particularly limited. It may be the sagger 2 shown in FIG. 1, the heat insulating material 521 shown in FIG. 7, a table, a plate, a cart, a refractory material (furnace wall, firebrick, etc.), or the like. The substrate may be any that comes into contact with the workpiece 9. The substrate may be a single body or an assembly of multiple members.

[0072] The type of carbon material forming the carburized layer 3 (carbon layer) is not particularly limited, and may be graphite (artificial graphite, natural graphite), graphitic materials (carbon materials containing graphite as the main component), soft carbon, hard carbon, amorphous carbon, activated carbon, carbon black, carbon nanotubes, carbon nanofibers, carbon microbeads, porous carbon, graphene, or the like.

[0073] The carbon layer may or may not be a carburized layer 3. In the case of a carburized layer 3, it is sufficient that carbon diffuses and penetrates into the interior of the substrate (surface of ceramic particles, gaps between particles). In the case of a non-carburized layer 3, for example, a carbon layer may be vapor-deposited (by chemical vapor deposition, physical vapor deposition, etc.) or bonded to the surface of the substrate (sagger 2, heat insulating material 521).

[0074] The surface of the carbon layer and the surface of the substrate may be the same or different (the carbon layer may be laminated on the surface of the substrate). That is, the carbon layer and the substrate may overlap each other or be independent of each other.

[0075] The thickness of the carbon layer is not particularly limited. It may be on the order of submicrons, microns, submillimeters, millimeters, etc. The thickness of the carbon layer (carburized layer 3) may be constant or may not be constant across the entire surface of the base (sagger 2, heat insulating material 521). For example, the thickness of the carburized layer 3 on the bottom surface of the inner surface of the sagger 2 may be thicker than the thickness of the carburized layer 3 on the side surfaces, or vice versa.

[0076] The heating temperature of the base body in the heating step is not particularly limited. It is sufficient that the carburizing gas is thermally decomposed in the carburizing step. The heater 41 may or may not be used in the carburizing step. That is, the carburizing gas may be thermally decomposed only by the temperature of the base body. Alternatively, the carburizing gas may be thermally decomposed while heating the heating chamber 45 with the heater 41 in addition to the temperature of the base body. A blower such as a fan may be placed in the heating chamber 45 to promote convection of the carburizing gas.

[0077] The cooling method for the heat treatment component 1 after the carburizing step is not particularly limited. Forced cooling or natural cooling (natural cooling) may be used. Furthermore, a base fabrication step for manufacturing a base may be performed before the heating step. Specifically, the base may be manufactured by first carrying the base (raw material for the base) before firing into a firing furnace, firing the base at a predetermined firing temperature (e.g., 1250°C), and then cooling the fired base in an oxygen-free state. Thereafter, the base may be subjected to the heating step and carburizing step described above. Of course, a general-purpose (commercially available) sagger 2 may be used as the base before the heating step.

[0078] The type of workpiece 9 is not particularly limited. The workpiece 9 may or may not be a battery material. When the workpiece 9 is a battery material, the battery material may be, for example, an electrode material (cathode material, anode material) of a secondary battery. The type of heat treatment furnace used to heat treat the workpiece 9 is not particularly limited. It may be a batch furnace or a continuous furnace. It may be a tunnel kiln, a roller hearth kiln, a rotary kiln, or the like. [Example]

[0079] The results of experiments carried out on the member for heat treatment 1 of the first embodiment (FIGS. 1 and 2) will be described below.

[0080] (sample) The samples used in the experiment were three types of members for heat treatment 1: Example 1 and Comparative Examples 1 and 2. Example 1 is the member for heat treatment 1 of the first embodiment. Example 1 is provided with a sagger 2 and a carburized layer 3 made of graphite. Comparative Example 1 is a sagger made of mullite (i.e., the sagger 2 of the first embodiment). Comparative Example 2 is a sagger made of graphite. Comparative Examples 1 and 2 are not provided with a carburized layer 3. The dimensions of the sagger 2 of Example 1 are the same as those of Comparative Examples 1 and 2.

[0081] (Battery material manufacturing method) The object to be treated 9 was lithium iron phosphate (a battery material (raw material)). In the experiment, first, the object to be treated 9 was placed inside each sample (Example 1, Comparative Examples 1 and 2). Next, the object to be treated 9 was subjected to a heat treatment under a nitrogen (oxygen-free) atmosphere under the conditions of a firing temperature of 700°C and a firing time of 3 hours, thereby producing a battery material.

[0082] (Experimental results) Hereinafter, the results of experiments conducted on the battery material (subject 9 after heat treatment) produced by the above-mentioned production method will be described. Note that "battery material produced using Example 1" will be abbreviated as the battery material of Example 1, "battery material produced using Comparative Example 1" will be abbreviated as the battery material of Comparative Example 1, and "battery material produced using Comparative Example 2" will be abbreviated as the battery material of Comparative Example 2.

[0083] (Powder characteristics) Table 1 shows the measurement results of the powder properties of the battery materials. The powder properties of each sample were measured using the same equipment and method under the same conditions. Specifically, particle size was measured using a laser diffraction scattering particle size analyzer. Tap density was measured using the method of ISO 3953 (250 taps / min). Pellet density is the density of pellets molded at a specified molding pressure (2000 kg / f). Powder electrical resistivity was measured using a HPRM-FA2 powder resistivity measurement device (Hantec Co., Ltd., Gunpo, Republic of Korea). [Table 1]

[0084] In the table, "D10" indicates the particle size at which 10% of particles have a particle size of D10 or less, "D50" indicates the particle size (median diameter) at which 50% of particles have a particle size of D50 or less, and "D90" indicates the particle size at which 90% of particles have a particle size of D90 or less. "Pellet density" indicates the density (compressed density) when the powder is compressed into a pellet. As shown in Table 1, the battery material of Example 1 has powder properties that are almost equivalent (close to those of Comparative Example 2) to the battery materials of Comparative Examples 1 and 2.

[0085] (About the crystal structure) The results of X-ray crystal structure analysis are shown in Table 2. The crystal structure of each sample was analyzed using the same equipment, method, and conditions. [Table 2]

[0086] In the table, "FWHM" indicates the full width at half maximum. As shown in Table 2, it can be seen that the battery material of Example 1 has a crystal structure that is almost the same as (close to) the crystal structure of Comparative Examples 1 and 2.

[0087] (Electrochemical properties) Table 3 shows the measurement results of the electrochemical properties (charge / discharge characteristics) of batteries (coin cells) manufactured from each sample's battery material. The electrochemical properties of each sample were measured using the same equipment and method under the same conditions. The room temperature during measurements was 25°C. The constant current / constant voltage charging method (CCCV method) was used for charging and discharging. [Table 3]

[0088] As shown in Table 3, it can be seen that the battery made from the battery material of Example 1 has a higher charge / discharge capacity (=discharge capacity / charge capacity×100) than the batteries made from the battery materials of Comparative Examples 1 and 2.

[0089] (summary) As shown in Tables 1 to 3, the battery material of Example 1 has properties (powder properties, crystal structure properties, electrochemical properties) equivalent to those of the battery materials of Comparative Examples 1 and 2. In particular, as shown in Table 3, with regard to charge / discharge capacity, which is an important aspect of battery performance, batteries made from the battery material of Example 1 have higher charge / discharge capacities than batteries made from the battery materials of Comparative Examples 1 and 2. Thus, according to Example 1, a battery material having properties equivalent to or better than those of Comparative Examples 1 and 2 can be produced.

[0090] Furthermore, from the viewpoint of contamination, Example 1 having a carburized layer 3 made of graphite and Comparative Example 2 made of graphite have a smaller effect on battery materials than Comparative Example 1 made of mullite. Furthermore, from the viewpoint of durability, Example 1 is less susceptible to deterioration over time (cracks, chips, wear, etc.) than Comparative Example 2. Thus, when the characteristics, the effect on battery materials, and durability are comprehensively taken into consideration, Example 1 is superior to Comparative Examples 1 and 2. [Explanation of symbols]

[0091] 1: heat treatment member, 2: sagger (base, carrier), 20: opening, 21: inner surface, 22: recess, 3: carburized layer (carbon layer), 4: carburizing furnace, 40: housing, 400: outer shell, 401: heat insulating material, 402: gas vent, 41: heater, 42: hearth, 43: tray, 44: thermocouple, 45: heating chamber, 46: carburizing gas supply line, 47: nitrogen gas supply line, 5: rotary kiln (heat treatment furnace), 50: tire, 51: rotating cylinder support, 510: roller, 52: rotating cylinder (heat treatment member), 520: outer shell, 521: heat insulating material (base), 521a: inner surface, 53: stand, 54: heat treatment chamber, 9: object to be treated

Claims

1. A heat treatment member that comes into contact with a workpiece to be heat treated in a heat treatment furnace, a ceramic substrate; a carbon layer disposed on the surface of the substrate and in contact with the workpiece; A heat treatment member comprising:

2. 2. The heat treatment member according to claim 1, wherein the substrate is a carrier for carrying the object to be treated.

3. the conveying tool is a sagger in which the object to be treated is accommodated, 3. The heat treatment member according to claim 2, wherein the carbon layer is disposed on the inner surface of the sagger.

4. 2. The member for heat treatment according to claim 1, wherein the ceramic is mullite or alumina.

5. 2. The member for heat treatment according to claim 1, wherein the carbon layer is a carburized layer formed by carburizing treatment.

6. 2. The heat treatment member according to claim 1, wherein the object to be treated is a battery material.

7. A method for producing a member for heat treatment according to claim 5, a heating step of heating the substrate; a carburizing step in which a carburizing gas is supplied to the surface of the heated substrate, the carburizing gas is thermally decomposed using the temperature of the substrate, and carbon generated by the thermal decomposition is diffused and penetrated into the surface of the substrate to form the carburized layer; A method for producing a member for heat treatment having the above structure.

8. The temperature reached by the base body in the heating step is defined as the carburizing temperature, and the time required for the carburizing step is defined as the carburizing time, the carburizing temperature is 400°C or higher and 1000°C or lower, 8. The method for producing a member intended for heat treatment according to claim 7, wherein the carburizing time is from 20 minutes to 120 minutes.

9. the carburizing gas contains one or more gases selected from propane gas, butane gas, acetylene gas, and natural gas; 8. The method for producing a member intended for heat treatment according to claim 7, wherein the amount of the carburizing gas supplied in the carburizing step is 0.33% or more, with the mass of the substrate being 100%.

10. the base is a sagger having an opening and accommodating the object to be treated therein; the carburized layer is disposed on the inner surface of the sagger; The method for manufacturing a member intended for heat treatment according to claim 7 , wherein in the carburizing step, the sagger is oriented so that the opening is not sealed.

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