KR20210132771A - Graphite muffle structure - Google Patents

Abstract

The present invention relates to a graphite muffle structure. The graphite muffle structure according to an embodiment of the present invention is a graphite muffle structure of a furnace using nitrogen atmospheric gas comprising: a heat treating furnace main body which has an interior space; an insulation member which is formed to cover the interior space; and a heater which is installed inside the interior space and is heated to a set temperature. The graphite muffle structure comprises: a first graphite muffle which is located inside the insulation member, provides a sealed space of nitrogen gas atmosphere, and is made of graphite material; and a second graphite muffle which seals the surroundings of the first graphite muffle by covering the interior space in which the first graphite muffle is installed and is made of graphite material. The graphite muffle structure significantly reduces oxygen concentration inside the furnace by being applied in the furnace using nitrogen atmospheric gas.

Description

Graphite muffle structure {GRAPHITE MUFFLE STRUCTURE}

Embodiments of the present invention relate to graphite muffle structures.

Oxygen in the atmosphere is converted into CO gas by combining with carbon inside the furnace. And the amount of carbon emitted from the carbon structure is extremely small and may not be involved in the durability of the structure.

If the carbon structure is applied to the structure inside the furnace, the oxygen concentration in the furnace may be very low, which is advantageous for optimizing the atmosphere furnace.

Republic of Korea Patent Publication No. 10-2000-0023444 (April 25, 2000, published)

An object of the present invention is to provide a graphite muffle structure that can be applied to a nitrogen atmosphere gas furnace to significantly reduce the oxygen concentration inside the furnace in order to solve the above problems.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. Moreover, it will be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

A graphite muffle structure according to an embodiment of the present invention includes a heat treatment furnace body having an inner space, a heat insulating member formed to surround the inner space, and a heater installed in the inner space and heated to a set temperature. A graphite muffle structure for a furnace, wherein the graphite muffle structure includes: a first graphite muffle located inside the heat insulating member and providing a closed space of a nitrogen gas atmosphere, made of a graphite material; and a second graphite muffle that surrounds the inner space in which the first graphite muffle is installed to seal the periphery of the first graphite muffle, and is made of a graphite material.

The first graphite muffle is installed to be located in the center of the inner space, and may be formed by assembling a plurality of graphite units divided for each zone.

The second graphite muffle is disposed in close contact with the inner wall surface of the heat insulating member, and may be formed by assembling a plurality of graphite units divided for each zone.

The first graphite muffle may include: a first upper graphite unit horizontally disposed on an upper portion of the sealed space; a first lower graphite unit that is horizontally disposed in the lower portion of the closed space and is installed to face the first upper graphite unit with a length corresponding to that of the first upper graphite unit; and a first side graphite unit assembled in a direction crossing both ends of the first upper graphite unit and the first lower graphite unit.

It further includes; a support member for reinforcing and supporting the assembly structure of the first graphite muffle.

The support member is coupled to cover the upper portion of the first upper graphite unit from the outside, the horizontal coupling portion made of a graphite material; and a bending extension part bent downward from both ends of the horizontal coupling part to wrap and fix a part of the first side graphite unit, and made of a graphite material.

The support member is installed upright on the support of the heat treatment furnace body to position the lower portion of the first lower graphite unit at a predetermined height, and a standing portion made of a graphite material; further includes.

The second graphite muffle may include: a second upper graphite unit closely coupled to the heat insulating member at a predetermined interval from the first upper graphite unit; a second lower graphite unit closely coupled to the heat insulating member at a predetermined distance from the second upper graphite unit; and a second side graphite unit assembled in a direction crossing both ends of the second upper graphite unit and the second lower graphite unit.

a sampling gas suction nozzle connected to a sampling gas suction port, which is formed to communicate with the inside of the sealed space from the outside through vertical centers of widths of the first upper graphite unit and the second upper graphite unit; and a plurality of nitrogen gas input nozzles which are formed in communication with the inside of the second graphite muffle by penetrating the second upper graphite unit up and down and connected to the nitrogen gas inlet; including, the sampling gas suction nozzle and the plurality of Each of the nitrogen gas input nozzles may be made of a graphite material.

The heater may include: a plurality of first heaters extending in a horizontal direction to a central position of an inner width of the inner space and disposed at intervals on the upper portion of the first graphite muffle; and a plurality of second heaters positioned side by side under the plurality of first heaters, extending in the horizontal direction to a central position of the inner width of the inner space, and disposed at intervals below the first graphite muffle. and a first heater supporting member for supporting the first heater is provided under the first heater, and a second heater supporting member supporting the second heater is provided under the second heater, and the second heater supporting member is provided under the first heater. 1, 2 The heater support member may be made of a graphite material.

According to the graphite muffle structure of the present invention, it is possible to significantly lower the oxygen concentration inside a furnace using nitrogen as an atmosphere gas, so it is possible to optimize a furnace using nitrogen atmosphere gas.

As a specific example, the double graphite muffle type has the advantage of maintaining an optimal furnace atmosphere with a minimum amount of nitrogen gas. In particular, while applying the double graphite muffle type, the heater support, nitrogen gas nozzle, sampling gas nozzle, and muffle support are all made of graphite material to significantly lower the oxygen atmosphere concentration inside the furnace and improve airtightness. have.

In addition, according to the present invention, the first and second graphite muffles are manufactured in a prefabricated manner, and there is an advantage that parts can be replaced in case of damage.

In addition to the above-described effects, the specific effects of the present invention will be described together while describing specific details for carrying out the invention below.

1 is a diagram schematically illustrating a graphite muffle structure according to an embodiment of the present invention.
2 to 6 are conceptual views illustrating the detailed configuration of a graphite muffle structure according to an embodiment of the present invention.

Hereinafter, with reference to the drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly explain the present invention, parts irrelevant to the description are omitted, and the same reference numerals are given to the same or similar elements throughout the specification. Further, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted.

In describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the nature, order, order, or number of the elements are not limited by the terms. When it is described that a component is “connected”, “coupled” or “connected” to another component, the component may be directly connected or connected to the other component, but other components may be interposed between each component. It will be understood that each component may be “interposed” or “connected”, “coupled” or “connected” through another component.

In addition, in implementing the present invention, components may be subdivided for convenience of description, but these components may be implemented in one device or module, or one component may include a plurality of devices or modules. It may be implemented by being divided into .

1 is a view showing a schematic form of a graphite muffle structure and a nitrogen atmosphere gas furnace including the same according to an embodiment of the present invention.

The graphite muffle structure 200 according to an embodiment of the present invention refers to the muffle structure of the nitrogen atmosphere gas furnace 100 .

The nitrogen atmosphere gas furnace 100 includes a heat treatment furnace body 110 having an inner space, a heat insulating member 120 formed to surround the inner space, and a heater 130 installed in the inner space and heated to a set temperature. 140).

The graphite muffle structure 200 according to the embodiment of the present invention includes a first graphite muffle 210 located inside the heat insulating member 120 and made of a graphite material that provides a sealed space of a nitrogen gas atmosphere.

In addition, the graphite muffle structure 200 according to the embodiment of the present invention surrounds the inner space 113 in which the first graphite muffle 210 is installed to seal the periphery of the first graphite muffle 210 and is made of a graphite material. A second graphite muffle 220 is included.

As such, according to the embodiment of the present invention, the second graphite muffle 220 is provided simultaneously with the first graphite muffle 210, which helps to significantly lower the oxygen concentration, and can sufficiently improve airtightness.

Hereinafter, a nitrogen atmosphere gas furnace 100 to which the graphite muffle structure 200 according to an embodiment of the present invention is applied will be briefly described.

For example, the heat treatment furnace body 110 has a sealed inner space (113). Specifically, the heat treatment furnace body 110 includes an upper body 111 , a plurality of side wall bodies 112 , and a support 115 as shown. The upper body 111 is coupled in close contact with the upper surface of the heat insulating member 120 . The plurality of side wall bodies 112 are coupled in close contact with both sides of the heat insulating member 120 . The support 115 is in close contact with the lower surface of the heat insulating member 120 to support the heat insulating member 120 to a set height.

For example, the heat insulating member 120 is provided inside the heat treatment furnace body 110 . For example, the heat insulating member 120 has a rectangular cross-sectional shape surrounding the outside of the inner space (113). The heat insulating member 120 may be made of a ceramic fiber material.

For example, the heaters 130 and 140 are installed in the inner space through the heat treatment furnace body 110 and the heat insulating member 120, and may be heated to a set temperature. The heaters 130 and 140 include a plurality of first heaters 130 and a plurality of second heaters 140 . The plurality of first heaters 130 may extend through the plurality of side wall bodies 112 and the heat insulating member 120 in the horizontal direction to a central position of the inner width of the inner space 113 to protrude. Specifically, the plurality of first heaters 130 may be horizontally disposed on the first graphite muffle 210 at intervals therebetween. The plurality of second heaters 140 are positioned side by side under the plurality of first heaters 130 . The plurality of second heaters 140 may extend through the plurality of side wall bodies 112 and the heat insulating member 120 in the horizontal direction to a central position of the inner width of the inner space 113 to protrude. Specifically, the plurality of second heaters 140 may be horizontally disposed at intervals below the first graphite muffle 210 .

For example, the plurality of first heaters 130 are positioned at a predetermined height above the sealed inner space provided inside the heat insulating member 120 , and each of the plurality of first heaters 130 is a left and right side wall body. It has a structure that protrudes to face the inner width central position of the inner space 113 through the 112 and the heat insulating member 120 in the horizontal direction. Similarly, the plurality of second heaters 140 are positioned parallel to the lower side of the plurality of first heaters 130 , and each of the plurality of second heaters 140 includes the left and right side wall bodies 112 and the heat insulating member. It has a structure that penetrates through 120 in the horizontal direction and protrudes to face up to the central position of the inner width of the inner space 113 . Accordingly, the first graphite muffle 210 is positioned between the plurality of first heaters 130 and the plurality of second heaters 140 , and the temperature of the nitrogen gas atmosphere forming space may be heated to a set temperature.

Graphite Muffle Structure

Hereinafter, the graphite muffle structure according to an embodiment of the present invention will be described in detail.

In the drawings, FIGS. 2 to 6 are conceptual views illustrating the detailed configuration of a graphite muffle structure according to an embodiment of the present invention.

The graphite muffle structure 200 according to an embodiment of the present invention includes a first graphite muffle 210 and a second graphite muffle 220 .

The first graphite muffle 210 is located inside the heat insulating member 120, provides a closed space in a nitrogen gas atmosphere, and is made of a graphite material.

The second graphite muffle 220 surrounds the inner space 113 in which the first graphite muffle 210 is installed to seal the periphery of the first graphite muffle 210 and is made of a graphite material.

In this way, the second graphite muffle 220 is provided simultaneously with the first graphite muffle 210, which helps to significantly lower the oxygen concentration, and can sufficiently improve airtightness.

Specifically, the first graphite muffle 210 is installed to be located in the center of the inner space 113, and has a prefabricated structure formed by assembling a plurality of graphite units divided for each zone.

The first graphite muffle 210 has the advantage of lowering the oxygen concentration inside the closed space 215 and securing a nitrogen atmosphere.

In addition, the second graphite muffle 220 is disposed in close contact along the inner wall surface of the heat insulating member 120, and has a prefabricated structure formed by assembling a plurality of graphite units divided for each zone.

And the second graphite muffle 220 is sealed in a structure that surrounds the inner space 113 in which the first graphite muffle 210 is installed.

As such, the first and second graphite muffles 210 and 220 are made of a graphite material and combine with oxygen in the atmosphere to generate CO, and may lower the oxygen atmosphere inside the furnace to at least 20 ppm or less. Instead, airtightness that may be weakened due to the assembly structure of the first graphite muffle 210 may be supplemented by applying the second graphite muffle 220 together. As a result, airtightness can be effectively improved while significantly lowering the oxygen concentration.

And since the first graphite muffle 210 and the second graphite muffle 220 are both made of a prefabricated coupling structure, there is an advantage compared to the integrated metal muffle structure in that partial replacement is possible in case of damage.

As a specific example, the first graphite muffle 210 includes a first upper graphite unit 211 , a first lower graphite unit 212 , and a first side graphite unit 213 .

Here, the first upper graphite unit 211 is horizontally disposed on the upper portion of the closed space 215 . In addition, the first lower graphite unit 212 may be horizontally disposed in the lower portion of the closed space 215 and installed to face the first upper graphite unit 211 with a length corresponding to the first upper graphite unit 211 . In addition, the first side graphite unit 213 may be assembled in a direction crossing both ends of the first upper graphite unit 211 and the first lower graphite unit 212 .

The second graphite muffle 220 includes a second upper graphite unit 221 , a second lower graphite unit 222 , and a second side graphite unit 223 .

Here, the second upper graphite unit 221 refers to an assembly part made of a graphite material that is closely coupled to the heat insulating member 120 at a predetermined distance from the first upper graphite unit 211 . In addition, the second lower graphite unit 222 refers to an assembly part made of graphite that is closely coupled to the heat insulating member 120 at a predetermined interval from the second upper graphite unit 221 . And the second side graphite unit 223 refers to an assembly part made of graphite material that is assembled in a direction crossing both ends of the second upper graphite unit 221 and the second lower graphite unit 222 .

The first graphite muffle 210 is configured to have a graphite material, and may have a prefabricated structure that can be partially replaced when damaged. In addition, the first upper graphite unit 211 is connected to the first side graphite unit 213 through assembly, the first step 2111 and the first protrusion 2113 are the second step 2131 and the second 2 is coupled to the protrusion 2133 and a step in the shape of a, it is possible to secure the airtightness at the assembly site (see FIG. 2).

A support member 230 may be further included to reinforce the prefabricated structure of the first graphite muffle 210 . The support member 230 reinforces and supports the assembly structure of the first graphite muffle 210 and is made of a graphite material. Specifically, the support member 230 includes a horizontal coupling part 231 coupled to cover the upper portion of the first upper graphite unit 211 from the outside, and the first side surface bent downward from both ends of the horizontal coupling part 231 . It includes a bent extension part 233 that is fixed by wrapping a part of the graphite unit 213 . And the support member 230 further includes a standing portion 235 to position and support the lower portion of the first lower graphite unit 212 on a predetermined height. At this time, the horizontal coupling portion 231 , the bent extension portion 233 , and the standing tongue portion 235 are all made of a graphite material and have the advantage of significantly lowering the oxygen concentration (see FIG. 3 ).

The second graphite muffle 220 is configured to have a graphite material as a whole as described above, and has a prefabricated structure that can be partially replaced when damaged, thereby significantly reducing maintenance costs. In addition, the second graphite muffle 220 blocks the inflow of oxygen from the outside, and fundamentally blocks the nitrogen gas flowing into the outside. In particular, the nitrogen gas inside the sealed space 215 is prevented from coming out of the first graphite muffle 210, and a small amount of nitrogen gas is introduced into the sealed space 215 from the outside of the first graphite muffle 210. This has the advantage of saving the amount of nitrogen gas used (see FIG. 4).

Furthermore, according to an embodiment of the present invention, it further includes a first heater support member 241 and a second heater support member 243 . The first heater support member 241 is in contact with the lower portion of the first heater 130 inside the heat insulating member 120 to support the first heater 130 . The first heater support member 241 is made of a graphite material and has the advantage of lowering the oxygen concentration. The first heater support member 241 may be interposed between the upper surface of the first upper graphite unit 211 and the lower surface of the first heater 130 to stably support the first heater 130 . There is (see Fig. 5).

In addition, the second heater supporting member 243 is in contact with the lower portion of the second heater 140 inside the heat insulating member 120 to support the second heater (140). The second heater support member 243 may be positioned between the structure protruding upward from the top of the support 115 of the main body of the heat treatment furnace and the second heater 140 . The second heater support member 243 is made of a graphite material in the same manner as the first heater support member 241 and may be used to lower the oxygen concentration (see FIG. 5 ).

In addition, according to the embodiment of the present invention, it further includes a sampling gas suction nozzle 250 and a plurality of nitrogen gas input nozzles 260 .

The sampling gas suction nozzle 250 is formed in communication with the inside of the sealed space 215 from the outside by penetrating the respective width centers of the first upper graphite unit 211 and the second upper graphite unit 221 up and down. It is connected to the gas inlet 151 .

The plurality of nitrogen gas input nozzles 260 are respectively formed at positions symmetrical on both sides with respect to the sampling gas suction nozzle 250, and penetrate the second upper graphite unit 221 up and down to penetrate the second graphite muffle 220. It is formed in communication to the inside of the and is connected to the nitrogen gas inlet (161).

At this time, each of the sampling gas suction nozzle 250 and the plurality of nitrogen gas input nozzles 260 is made of a graphite material.

As such, according to the embodiment of the present invention, in addition to the first and second graphite muffles 210 and 220, the support member 230, the heater support member 240, the sampling gas suction nozzle 250, the nitrogen gas input nozzle ( 260) are all made of graphite, which can greatly reduce the oxygen concentration in a furnace using nitrogen as an atmosphere gas, which can greatly help optimize the furnace.

6 is a view showing a side assembly shape of a graphite muffle structure included in a nitrogen atmosphere gas using furnace according to an embodiment of the present invention.

As shown, the graphite muffle structure 200 includes a first graphite muffle 210 and a second graphite muffle 220 . The first graphite muffle 210 and the second graphite muffle 220 have an advantage that they can be partially replaced in case of damage due to external factors such as impact because they are all assembled structures. Accordingly, there is an advantageous effect that the maintenance cost is reduced compared to the conventional one-piece structure.

In addition, since the first graphite muffle 210 and the second graphite muffle 220 have a double structure, the atmosphere in the furnace is extremely excellent, and there is an advantageous effect of reducing the amount of nitrogen gas used. Even, the support member 230, the heater support member 240, the sampling gas suction nozzle (250, see FIG. 5), and the nitrogen gas input nozzle (260, see FIG. 5) are all made of graphite, which greatly increases the oxygen concentration. It has the advantage of lowering and reducing the amount of nitrogen gas used.

As described above, according to the configuration and operation of the present invention, it is possible to significantly lower the oxygen concentration in the furnace by applying the graphite muffle structure, and thus there is an advantage that the nitrogen atmosphere gas furnace can be optimized. As a specific example, in the case of a furnace using nitrogen atmosphere gas, it is possible to maintain an optimal internal atmosphere of the furnace with a minimum amount of nitrogen gas as a double graphite muffle type.

In addition, since the first graphite muffle is manufactured in a prefabricated manner, it is possible to partially replace it in case of damage.

However, in the case of this prefabricated structure, there is a disadvantage in that the airtightness is low compared to the conventional metal material integrated muffle, but the airtightness can be sufficiently improved by additionally configuring the second graphite muffle surrounding the outer periphery together with the first graphite muffle.

The second graphite muffle is also manufactured in a prefabricated manner, so that it can be partially replaced in case of damage, making maintenance work simple and cost reduction possible.

And in order to structurally reinforce the first graphite muffle of the prefabricated structure, a support member is further installed for each assembly section, and the material of the horizontal coupling part, the bending extension part, and the standing part constituting the support member is also composed of graphite and oxygen concentration can be lowered and semi-permanent use is possible.

The second graphite muffle may serve to block oxygen to the outside and fundamentally block nitrogen gas flowing to the outside of the first graphite muffle, thereby optimizing the nitrogen atmosphere gas furnace.

As such, according to the application of the first and second graphite muffle structures, the nitrogen gas inside the first graphite muffle cannot come out, and conversely, a small amount of nitrogen gas can be introduced from the outside of the first graphite muffle to the inside. consumption can be saved. As the second graphite muffle is installed outside the first graphite muffle, the oxygen concentration can be maintained below a set level (eg, 20 ppm, etc.).

As described above, the present invention has been described with reference to the illustrated drawings, but the present invention is not limited by the embodiments and drawings disclosed in the present specification. It is obvious that variations can be made. In addition, even if the effect of the configuration of the present invention is not explicitly described and described while describing the embodiment of the present invention, it is natural that the effect predictable by the configuration should also be recognized.

100: furnace using nitrogen atmosphere gas
110: heat treatment furnace body
111: upper body
112: side wall body
113: inner space
115: support
120: insulation member
130: first heater
140: second heater
151: sampling gas inlet
161: nitrogen gas inlet
200: graphite muffle structure
210: first graphite muffle
211: first upper graphite unit
2111: first step part
2113: first protrusion
2131: second step portion
2133: second protrusion
212: first lower graphite unit
213: first side graphite unit
215: inner space
220: second graphite muffle
221: second upper graphite unit
222: second lower graphite unit
223: second side graphite unit
230: support member
231: horizontal coupling part
233: bend extension
235: standing tongue
240: heater support member
241: first heater support member
243: second heater support member
250: sampling gas suction nozzle
260: nitrogen gas input nozzle

Claims (10)

A graphite muffle structure of a nitrogen atmosphere gas furnace comprising a heat treatment furnace body having an inner space, a heat insulating member formed to surround the inner space, and a heater installed in the inner space and heated to a set temperature,
The graphite muffle structure is
a first graphite muffle located inside the heat insulating member and providing a closed space in a nitrogen gas atmosphere, and made of a graphite material; and
a second graphite muffle made of a graphite material, enclosing the inner space in which the first graphite muffle is installed and sealing the periphery of the first graphite muffle;
A graphite muffle structure comprising a.
According to claim 1,
The first graphite muffle,
Installed so as to be located in the center of the inner space, characterized in that formed by assembling a plurality of graphite units divided by zone
Graphite muffle structure.
3. The method of claim 2,
The second graphite muffle,
Disposed in close contact along the inner wall surface of the heat insulating member, characterized in that formed by assembling a plurality of graphite units divided by zone
Graphite muffle structure.
According to claim 1,
The first graphite muffle,
a first upper graphite unit horizontally disposed on an upper portion of the closed space;
a first lower graphite unit that is horizontally disposed in the lower portion of the closed space and is installed to face the first upper graphite unit with a length corresponding to that of the first upper graphite unit; and
a first side graphite unit assembled in a direction crossing both ends of the first upper graphite unit and the first lower graphite unit;
A graphite muffle structure comprising a.
5. The method of claim 4,
a support member for reinforcing and supporting the assembly structure of the first graphite muffle;
A graphite muffle structure further comprising a.
6. The method of claim 5,
The support member is
a horizontal coupling part which is coupled to cover the upper part of the first upper graphite unit from the outside, and made of a graphite material; and
a bent extension part bent downward from both ends of the horizontal coupling part to wrap around a part of the first side graphite unit and fixed, and made of a graphite material;
A graphite muffle structure comprising a.
7. The method of claim 6,
The support member is
a standing portion that is installed on the support of the heat treatment furnace body so as to position the lower portion of the first lower graphite unit at a predetermined height, and is made of a graphite material;
A graphite muffle structure further comprising a.
5. The method of claim 4,
The second graphite muffle,
a second upper graphite unit closely coupled to the heat insulating member at a predetermined distance from the first upper graphite unit;
a second lower graphite unit closely coupled to the heat insulating member at a predetermined distance from the second upper graphite unit;
a second side graphite unit assembled in a direction crossing both ends of the second upper graphite unit and the second lower graphite unit;
A graphite muffle structure comprising a.
9. The method of claim 8,
a sampling gas suction nozzle connected to a sampling gas suction port, which is formed to communicate with the inside of the sealed space from the outside through vertical centers of widths of the first upper graphite unit and the second upper graphite unit; and
It includes; a plurality of nitrogen gas input nozzles formed by penetrating the second upper graphite unit up and down and communicating to the inside of the second graphite muffle, and connected to the nitrogen gas inlet;
Each of the sampling gas suction nozzle and the plurality of nitrogen gas input nozzles is made of a graphite material
Graphite muffle structure.
10. The method of claim 9,
The heater includes a plurality of first heaters disposed at intervals on the upper portion of the first graphite muffle, and a plurality of first heaters disposed side by side under the plurality of first heaters, and disposed at intervals below the first graphite muffle A plurality of second heaters being
The first and second heater support members made of graphite are provided on the lower portions of the first and second heaters, respectively.
Graphite muffle structure.

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