JP4323064B2 - Continuous degreasing furnace, method for producing porous silicon carbide sintered body - Google Patents

Description

従って、本実施形態の前記実施例によれば以下のような効果を得ることができる。
【００６５】
（１）前記実施例１〜５では、成形、乾燥、脱脂、焼成を順に行ってハニカムフィルタ１を製造するにあたり、連続脱脂炉２１の加熱搬送路における低温領域のみならず高温領域においても排気をしながら脱脂を行っている。また、参考例では、連続脱脂炉２１の加熱搬送路における高温領域において排気をしながら脱脂を行っている。
【００６６】
そのため、前記各実施例では気体排出手段４６を構成するエジェクタ４８をマッフル２３における高温領域にも設けている。従って、エジェクタ４８の配設位置の温度が高くなることから、冷却されて結露が発生する前に、気体をマッフル２３外に排出させることができる。従って、結露によって生じたタールＴ１の垂れ・付着という問題が解消され、それに起因する品質や生産性の低下を防止することができる。
【００６７】
即ち、タールＴ１の付着によって製品が汚れて見栄えが悪くなるようなことがなく、外観面での品質が向上する。また、付着したタールＴ１を除去する作業が不要になり、生産性の低下が防止される。しかも、炭化珪素成形体Ｍ１の端面９ａ，９ｂへのタールＴ１の付着がなくなる結果、封止体１４の脱落が未然に防止され、強度面での品質も向上する。
【００６８】
なお、各実施例によって得られる焼成品は、残炭率が０．２％以下かつ破壊強度が４０ＭＰａ以上であって端部開口が交互に封止されたハニカムフィルタ１である。従って、圧力損失が小さくて濾過能力が高いばかりでなく、高温での使用に適し、しかも熱応力による破壊が起こりにくい、という極めて好適な諸性能を備えたハニカムフィルタ１となる。
【００６９】
（２）前記実施例１〜４，参考例では、加熱ゾーンを流れる気体の流速を５００ｍｍ／秒以上に設定しているため、気体がマッフル２３内にて滞留しにくくなる。従って、マッフル２３との接触により冷やされて結露を発生させてしまう前に、気体を確実にマッフル２３外に排出させることができる。
【００７０】
（３）前記各実施例では、エジェクタ４８によって気体を強制的に排出する構成を採用している。従って、流速を比較的簡単に速くすることができるとともに、流速の制御を比較的簡単に行うことができる。
【００７１】
（４）前記各実施例では、ヒータ４９によってエジェクタ４８が加熱されることにより、そこを通過する気体が冷えにくくなる。その結果、エジェクタ４８内での結露の発生をより確実に防止することができる。従って、エジェクタ４８の詰まりが防止され、気体排出能力の低下を未然に防止することができる。
【００７２】
（５）前記各実施例では、脱脂時に炭化珪素成形体Ｍ１を酸素濃度が１％〜２０％の雰囲気下にて有機バインダが分解しうる温度に加熱している。従って、脱脂時における生産性の低下や引火を伴うことなく、品質及び強度に優れた脱脂品、ひいては品質及び強度に優れた焼成品を得ることができる。
【００７３】
（６）前記各実施例では、連続脱脂炉２１を用いて脱脂を行っている。このため、バッチ式の炉で脱脂を行う場合に比べ、そもそも生産性に優れている。
（７）気体導入手段４１はマッフル２３内において横方向から気体を噴出する構成になっている。従って、前記気体は、横置きされた炭化珪素成形体Ｍ１の各セル内をそのセル長手方向に沿ってスムーズに流れることができる。従って、炭化珪素成形体Ｍ１に対して確実にかつ効率よく気体を供給することができ、ムラなく均一に脱脂をすることができる。このことは強度面での品質の向上にもつながる。
【００７４】
（８）天井部２３ｃは幅方向に傾斜した傾斜面になっている。言い換えると、天井部２３ｃは非水平面になっている。従って、たとえタールＴ１が発生したとしても、タールＴ１が傾斜面を伝わってマッフル２３の幅方向に流れてしまう。このため、タールＴ１が搬送経路上に垂れにくくなり、タールＴ１の付着を確実に防止することができる。
【００７５】
（９）マッフル２３の出口部２３ｂの断面積は、マッフル２３の中央部の断面積に比べて小さくなっている。従って、マッフル２３内の温度制御がしやすくなる。これに加えて、出口部２３ｂから熱が逃げにくくなる結果、熱のロスが少なくなり、経済性が向上する。
【００７６】
なお、本発明の実施形態は以下のように変更してもよい。
【００７７】
・ マッフル２３の天井部２３ｃは実施形態のような断面円弧状に限定されることはなく、例えば幅方向に傾く単純な傾斜面になっていてもよい。また、天井部２３ｃを水平面にしてもよい。
【００７８】
・ マッフル２３の出口部２３ｂは狭窄していなくてもよく、中央部と同じ断面積であってもよい。
・ 実施形態のようなベルト式のコンベアに代え、例えばローラ式のコンベアを採用してもよく、さらにはコンベア機構以外のものを採用して搬送手段を構成してもよい。
【００７９】
・ 治具Ｇ１を用いることなく炭化珪素成形体Ｍ１をそのままコンベアベルト３１上に載置して脱脂を行ってもよい。
・ 脱脂時おける不活性気体として窒素以外のもの、例えばアルゴン等を用いることもできる。
【００８０】
・ エジェクタ４８のヒータ４９は不要であれば省略されてもよい。
・ 連続脱脂炉２１内においてマッフル２３は複数個並列に配置されていてもよい。
【００８１】
・ 気体排出手段４６はエジェクタ４８を用いないものであってもよい。即ち、気体排出手段４６は気体を強制的に排出するものでなくてもよい。
・ 実施形態においては、本発明の多孔質炭化珪素焼結体の製造方法を、ディーゼルエンジンに取り付けられる排気ガス浄化装置用のハニカムフィルタ１の製造方法として具体化していた。
【００８２】
勿論、本発明の多孔質炭化珪素焼結体の製造方法は、ハニカム状でないセラミックフィルタの製造方法として具体化されたり、フィルタ以外のもの（例えば熱交換器用部材等）の製造方法として具体化されることも可能である。
【００８３】
・ 前記実施形態では、本発明の連続脱脂炉２１を用いて炭化珪素成形体Ｍ１の脱脂を行う例を示した。しかし、この連続脱脂炉２１は、炭化珪素以外のセラミック質からなる成形体の脱脂に流用されることも可能である。
【００８４】
次に、特許請求の範囲に記載された技術的思想のほかに、前述した実施形態によって把握される技術的思想をその効果とともに以下に列挙する。
（１） 両端に入口部及び出口部を有するマッフルと、炭化珪素成形体を前記入口部から前記出口部に向かって搬送する搬送手段と、前記マッフル内を移動する前記炭化珪素成形体を脱脂可能温度に加熱する加熱手段と、前記マッフル内に低酸素濃度の気体を導入する気体導入手段と、前記マッフル外へ前記気体を排出する気体排出手段とを備える連続脱脂炉において、前記マッフルにおける加熱ゾーンを流れる前記気体の流速を５００ｍｍ／秒以上に設定したことを特徴とする連続脱脂炉。従って、この技術的思想１に記載の発明によると、流速値が大きくなる結果、気体が結露する前に排気されてしまうため、結露して生じた異物の垂れ・付着といった心配が少なくなる。
【００８５】
（２） 両端に入口部及び出口部を有するマッフルと、炭化珪素成形体を前記入口部から前記出口部に向かって搬送する搬送手段と、前記マッフル内を移動する前記炭化珪素成形体を脱脂可能温度に加熱する加熱手段と、前記マッフル内に低酸素濃度の気体を導入する気体導入手段と、前記マッフル外へ前記気体を排出する気体排出手段とを備える連続脱脂炉において、前記マッフルにおける加熱ゾーンの断面積を０．１ｍ²以下に設定したことを特徴とする連続脱脂炉。従って、この技術的思想２に記載の発明によると、加熱ゾーンの断面積が小さくなる結果、流速を容易に速くすることができるため、結露して生じた異物の垂れ・付着といった心配が少なくなる。
【００８６】
（３） 請求項１乃至４、技術的思想１，２のいずれか１つにおいて、前記気体導入手段は、前記マッフル内において横方向から前記気体を噴出していること。従って、この技術的思想３に記載の発明によれば、例えば横置きのハニカム構造物に対して確実にかつ効率よく気体を供給することができる。
【００８７】
（４） 請求項１乃至４、技術的思想１乃至３のいずれか１つにおいて、前記マッフルの天井部は幅方向に傾斜した傾斜面になっていること。従って、この技術的思想４に記載の発明によれば、たとえ結露によって異物が発生したとしても、その異物が傾斜面を伝わって幅方向に流れるため、搬送経路上に垂れにくくなる。
【００８８】
（５） 請求項１乃至４、技術的思想１乃至４のいずれか１つにおいて、前記マッフルの出口部の断面積は、前記マッフルの中央部の断面積に比べて小さいこと。従って、この技術的思想５に記載の発明によれば、温度制御がしやすくなることに加えて、熱のロスが少なくなることで経済的になる。
【００８９】
【発明の効果】
以上詳述したように、請求項１〜４に記載の発明によれば、異物の垂れ・付着に起因する品質や生産性の低下を防止することができる連続脱脂炉を提供することができる。
【００９０】
請求項５，６に記載の発明によれば、異物の垂れ・付着に起因する品質や生産性の低下を防止することができる多孔質炭化珪素焼結体の製造方法を提供することができる。
【図面の簡単な説明】
【図１】（ａ）は本発明を具体化した一実施形態の連続脱脂炉の全体正面図、（ｂ）はその連続脱脂炉を概略的に示した図。
【図２】図１（ａ）のＢ−Ｂ線における概略断面図。
【図３】図１（ａ）のＡ−Ａ線における概略断面図。
【図４】（ａ）は実施形態のマッフルの断面図、（ｂ）はマッフルにおける排気位置を説明するための概略図。
【図５】（ａ），（ｂ）は、気体排出手段のノズル部の断面図。
【図６】ハニカムフィルタの斜視図。
【図７】ハニカムフィルタの一部破断断面図。
【図８】（ａ）は本願発明者が先に提案しているマッフルの断面図、（ｂ）はマッフルにおける排気位置を説明するための概略図。
【符号の説明】
１…多孔質炭化珪素焼結体としてのハニカムフィルタ、２１…連続脱脂炉、２３…マッフル、２３ａ…入口部、２３ｂ…出口部、３１…搬送手段を構成する、コンベアベルト、３２…搬送手段を構成するモータ、３３…搬送手段を構成するプーリ、３５…加熱手段としてのヒータ、４１…気体導入手段、４６…気体排出手段、４８…気体排出手段を構成するエジェクタ、４９…ヒータ、Ｍ１…炭化珪素成形体、Ｚ２…高温領域としての均熱ゾーン。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a continuous degreasing furnace and a method for producing a porous silicon carbide sintered body.
[0002]
[Prior art]
The number of automobiles is increasing dramatically, and the amount of exhaust gas emitted from the internal combustion engine of the automobile is increasing rapidly in proportion to the number of automobiles. In particular, various substances contained in exhaust gas emitted from a diesel engine cause pollution, and are now having a serious impact on the world environment. Recently, research results have reported that particulates (diesel particulates) in exhaust gas sometimes cause allergic disorders and a decrease in the number of sperm. In other words, taking measures to remove particulates in exhaust gas is considered an urgent issue for humanity.
[0003]
Under such circumstances, various types of exhaust gas purification apparatuses have been proposed. A general exhaust gas purifying apparatus has a structure in which a casing is provided in the middle of an exhaust pipe connected to an exhaust manifold of an engine, and a filter having fine holes is disposed therein. As a material for forming the filter, there are ceramics in addition to metals and alloys. As a typical example of a filter made of ceramic, a honeycomb filter made of cordierite is known.
[0004]
Here, a general method for manufacturing a cordierite honeycomb filter is briefly introduced. First, a columnar honeycomb formed body is formed by continuously extruding a ceramic raw material through a mold of an extruder. After the honeycomb formed body is cut to a predetermined length, the cells of the cut honeycomb formed body are sealed in a checkered pattern. Next, the sealed honeycomb formed body is dried in an oxygen atmosphere to volatilize mainly the solvent in the formed body. Thereafter, the honeycomb molded body is put in a hot air circulation type degreasing furnace and degreased in an oxygen atmosphere, whereby organic components such as a binder in the molded body are mainly decomposed and removed. Degreasing leads to a reduction in the amount of residual carbon in the sintered body. The honeycomb molded body thus degreased is fired in a firing furnace. As a result, a desired honeycomb filter is completed.
[0005]
Recently, porous silicon carbide, a kind of non-oxide ceramic, has advantages such as high heat resistance, mechanical strength, high collection efficiency, chemical stability, and low pressure loss. A sintered body may be used as a filter forming material.
[0006]
However, it is difficult to say that suitable degreasing conditions have yet been found in the production of a honeycomb filter made of porous silicon carbide, and there is a drawback in that productivity improvement is limited in the current batch processing. . Therefore, the applicant of the present application newly conceived a continuous degreasing furnace 61 as schematically shown in FIG. 8, and attempted degreasing using this.
[0007]
  Continuation of Fig. 8 (a)DegreasingThe furnace 61 includes a muffle 62, a conveying means 63, a heating means (not shown), a gas introducing means 64, a gas discharging means 65, and the like. The muffle 62 has an inlet portion and an outlet portion at both ends. In FIG.8 (b), the left end is the entrance part side, and the right end is the exit part side. The inside of the muffle 62 is divided into 11 regions for convenience along the longitudinal direction. Conveying means 63 continuously conveys silicon carbide molded body 67 placed on jig 66 from the inlet portion toward the outlet portion. The heating means heats silicon carbide molded body 67 moving within muffle 62 to a degreasable temperature. The gas introduction means 64 introduces a gas having a low oxygen concentration into the muffle 62. On the other hand, the gas discharge means 65 provided in the vicinity of the inlet portion in the muffle 62 discharges the gas and the gas generated in the furnace to the outside of the muffle 62.
[0008]
[Problems to be solved by the invention]
However, in the case of the continuous degreasing furnace 61 shown in FIG. 8, gas such as methanol generated during degreasing is cooled, and condensation such as tar is likely to occur on the ceiling surface of the muffle 62. There was a problem of adhering to the silicon carbide molded body 67. Therefore, if degreasing and firing are performed in this state, the quality and productivity of the finally obtained product (porous silicon carbide sintered body) may be adversely affected.
[0009]
More specifically, there were problems such as the product becoming dirty and poor in appearance, and the work of removing the attached tar becomes necessary after the degreasing process. In addition, when tar adheres to the end face of the silicon carbide molded body 67, there is also a problem that the sealing portion can be easily removed.
[0010]
The present invention has been made in view of the above problems, and its purpose is to provide a continuous degreasing furnace and a porous silicon carbide sintered body capable of preventing deterioration in quality and productivity due to dripping and adhesion of foreign matter. It is in providing the manufacturing method of.
[0011]
[Means for Solving the Problems]
In view of the above problems, the present inventor has conducted extensive investigations and researches, and as a result, it has been found that dew condensation and adhesion of foreign matters are likely to occur near the inlet portion of the muffle where the gas discharge means is disposed. Further, the inventor of the present application pays attention to the fact that the temperature in the vicinity of the inlet portion in the muffle is low, and has also found that condensation tends to occur when the temperature at the exhaust position is low. Therefore, the inventor of the present application has further developed it based on such knowledge, and finally came up with the following invention.
[0012]
  That is, in order to solve the above-mentioned problem, in the invention according to claim 1, a muffle having an inlet portion and an outlet portion at both ends, and a silicon carbide molded body including silicon carbide powder and an organic binder are disposed from the inlet portion. Conveying means for conveying toward the outlet, heating means for heating the silicon carbide molded body moving in the muffle to a degreasable temperature, and gas in which oxygen concentration is set to 1% to 20% in the muffle A gas introducing means for introducing the gas, and a gas discharging means for discharging the gas to the outside of the muffle, the inlet portion side in the muffleFrom the exit to the exitTemperature rising zone,Soaking zone, Slow cooling zoneIs a continuous degreasing furnace provided withWhile providing the gas introduction means in all of the heating zone, soaking zone, and slow cooling zone in the muffle,The gas discharge means is disposed in the muffle.Heating zone andThe gist of the continuous degreasing furnace is that it is provided in a soaking zone, and the temperature of the soaking zone is set to a temperature at which an organic binder at 200 ° C. to 600 ° C. can be decomposed.
[0013]
  The invention according to claim 2 is the muffle according to claim 1.InsideIt was assumed that the flow rate of the gas flowing through was set to 500 mm / second or more.
  According to a third aspect of the present invention, in the first or second aspect, the gas discharge means includes an ejector that forcibly discharges the gas.
[0014]
  According to a fourth aspect of the present invention, in the third aspect, the ejector includes a heater.
  In invention of Claim 5, after shape | molding the silicon carbide molded object containing a silicon carbide powder and an organic binder, a drying process,From the entrance side to the exit sideHeating zone,Soaking zone, Slow cooling zoneIn the muffle whereFrom gas introduction meansA porous silicon carbide sintered body is obtained by sequentially performing a degreasing step and a firing step in a continuous degreasing furnace maintained in a low oxygen concentration atmosphere by introducing a gas having an oxygen concentration set to 1% to 20%. In the heating conveyance path of the continuous degreasing furnaceWhile introducing gas from the gas introducing means provided in all of the temperature raising zone, soaking zone, and slow cooling zone in the muffle,In the muffleHeating zone andSoaking zoneThe gas is discharged from the gas exhaust means provided in the outside of the muffle.A method for producing a porous silicon carbide sintered body, wherein the degreasing is performed while exhausting and setting the temperature of the soaking zone to a temperature at which an organic binder at 200 ° C. to 600 ° C. can be decomposed. The gist.
[0015]
  The invention according to claim 6 is the invention according to claim 5,Within the muffleFlowingAboveThe degreasing was performed by setting the gas flow rate to 500 mm / second or more.
[0017]
The “action” of the present invention will be described below.
According to invention of Claims 1-4, since the temperature of the arrangement | positioning position of a gas discharge means becomes high, before cooling and dew condensation generate | occur | produce, gas can be discharged | emitted out of a muffle. Therefore, the problem of dripping and adhering foreign matter caused by condensation can be solved, and deterioration of quality and productivity due to dripping and adhering foreign matter can be prevented.
[0018]
  According to the invention described in claim 2,In the muffleBy setting the flow velocity of the gas flowing through 500 mm / second or more, it becomes difficult for the gas to stay in the muffle. Therefore, the gas can be reliably discharged out of the muffle before it is cooled by contact with the muffle and causes condensation.
[0019]
According to the invention described in claim 3, since the gas is forcibly discharged by the ejector, the flow velocity can be relatively easily increased and the flow velocity can be controlled relatively easily. .
[0020]
According to the fourth aspect of the present invention, when the ejector is heated by the heater, the gas passing therethrough is hardly cooled, so that the occurrence of dew condensation in the ejector is more reliably prevented. Therefore, the ejector can be prevented from being clogged and the gas discharge capacity can be prevented from being lowered.
[0021]
  Claim 5, 6According to the invention described in (4), since the temperature at the exhaust position becomes high, the gas can be discharged out of the muffle before being condensed and causing condensation. Therefore, the problem of dripping and adhering foreign matter caused by condensation can be solved, and deterioration of quality and productivity due to dripping and adhering foreign matter can be prevented.
[0022]
  According to the invention described in claim 6,In the muffleBy setting the flow velocity of the gas flowing through 500 mm / second or more, it becomes difficult for the gas to stay in the muffle. Therefore, the gas can be reliably discharged out of the muffle before it is cooled by contact with the muffle and is condensed.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a method for manufacturing a ceramic honeycomb filter according to an embodiment of the present invention will be described with reference to FIGS.FIG.This will be described in detail based on the above.
[0024]
  First, in this embodimentMadeThe manufactured honeycomb filter 1 will be described. Since the honeycomb filter 1 removes diesel particulates, it is generally called a diesel particulate filter (DPF). The honeycomb filter 1 has a quadrangular prism shape, and its outer dimensions are set to 33 mm × 33 mm × 167 mm (see FIG. 6).
[0025]
These honeycomb filters 1 are made of a porous silicon carbide sintered body which is a kind of ceramic sintered body. The reason why the silicon carbide sintered body is adopted is that, in comparison with other ceramics, there is an advantage that mechanical strength, heat resistance, thermal conductivity and the like are particularly excellent.
[0026]
As shown in FIG. 7, the honeycomb filter 1 has a honeycomb structure composed of a large number of cells extending in the same direction. The reason for adopting the honeycomb structure is that there is an advantage that the pressure loss is small even when the amount of collected fine particles is increased. In the honeycomb filter 1, a plurality of through holes 12 having a substantially square cross section are regularly formed along the axial direction. Each through hole 12 is partitioned from each other by a thin cell wall 13. On the outer surface of the cell wall 13, an oxidation catalyst composed of a platinum group element (for example, Pt or the like), other metal elements and oxides thereof is supported. The opening of each through-hole 12 is sealed in a checkered pattern with a sealing body 14 (here, a porous silicon carbide sintered body) on either one of the end faces 9a and 9b. Accordingly, the end faces 9a and 9b as a whole have a checkered pattern. As a result, the honeycomb filter 1 is formed with a large number of cells having a square cross section. The cell density is set to about 200 cells / inch, the thickness of the cell wall 13 is set to about 0.3 mm, and the cell pitch is set to about 1.8 mm. Of the many cells, about half of the cells open at the upstream end surface 9a, and the remaining cells open at the downstream end surface 9b.
[0027]
The average pore diameter of the honeycomb filter 1 is preferably 1 μm to 50 μm, more preferably 5 μm to 20 μm. When the average pore diameter is less than 1 μm, the honeycomb filter 1 is significantly clogged due to the accumulation of fine particles. On the other hand, if the average pore diameter exceeds 50 μm, fine fine particles cannot be collected, and the filtration capacity is lowered.
[0028]
The porosity of the honeycomb filter 1 is preferably 30% to 70%, more preferably 40% to 60%. If the porosity is less than 30%, the honeycomb filter 1 becomes too dense and the exhaust gas may not be allowed to flow inside. On the other hand, if the porosity exceeds 70%, the honeycomb filter 1 has too many voids, so that the strength becomes weak and the particulate collection efficiency may be lowered.
[0029]
The residual carbon ratio of the honeycomb filter 1 is preferably 0.2% or less. The reason is that if the residual carbon ratio is 0.2% or less, the abundance ratio of silicon carbide in the sintered body is increased, and the fracture strength is improved. The breaking strength of the honeycomb filter 1 is preferably 40 MPa or more. The reason is that if the breaking strength is 40 MPa or more, even if the exhaust gas pressure or the vibration during traveling is applied to the honeycomb filter 1, the honeycomb filter 1 is hardly broken.
[0030]
Next, a procedure for manufacturing the honeycomb filter 1 will be described.
First, a ceramic raw material slurry used in an extrusion molding process and a sealing paste used in an end face sealing process are prepared in advance.
[0031]
As the ceramic raw material slurry, a mixture obtained by blending silicon carbide powder with a dispersion medium such as an organic binder and water by a predetermined amount and kneading is used. As the sealing paste, a silicon carbide powder blended with an organic binder, a lubricant, a plasticizer and water and kneaded is used.
[0032]
Examples of the organic binder include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyethylene glycol, phenol resin, and epoxy resin. The blending amount of the organic binder is usually preferably about 1 to 10 parts by weight with respect to 100 parts by weight of the silicon carbide powder.
[0033]
As the dispersion medium liquid, for example, alcohols such as methanol and organic solvents such as benzene can be used in addition to the water described above.
Next, the ceramic raw material slurry is put into an extruder and continuously extruded through a mold. Then, the extruded silicon carbide molded body M1 is dried in an oxygen atmosphere using a microwave dryer or a hot air dryer. Thereby, the dispersion medium liquid in silicon carbide molded body M1 is mainly volatilized. In this case, the drying temperature is preferably set to 100 ° C to 200 ° C. Thereafter, the silicon carbide molded body M1 that has undergone the drying process is cut into equal lengths to obtain a quadrangular columnar silicon carbide molded body M1 having a honeycomb structure.
[0034]
Further, a predetermined amount of sealing paste is filled into one side opening of each cell of the silicon carbide molded body M1 that has undergone the molding process, and both end faces 9a and 9b are sealed in a checkered pattern. Here, you may dry again in order to dry the sealing paste.
[0035]
Next, the organic binder mainly in the silicon carbide molded body M1 is decomposed and removed by degreasing the silicon carbide molded body M1 that has passed through the drying step using the continuous degreasing furnace 21. The continuous degreasing furnace 21 and the degreasing method using the same will be described in detail later.
[0036]
Next, the silicon carbide molded body M1 that has undergone the degreasing process is fired in a firing furnace maintained in an inert gas atmosphere such as argon. As a result, the desired honeycomb filter 1 is completed. In this case, the firing temperature is preferably set to about 2000 ° C. to 2200 ° C., the firing time is set to 0.1 hour to 5 hours, and the furnace pressure is set to normal pressure.
[0037]
Then, the structure of the continuous degreasing furnace 21 used in this embodiment is demonstrated based on FIGS.
As shown in FIG. 1B and the like, a horizontally long main body frame 22 constituting the continuous degreasing furnace 21 is supported in a horizontal manner by a tubular muffle 23 made of a heat-resistant material. An inlet purge chamber 24 is provided in the vicinity of the inlet 23 a of the muffle 23. A carry-in section 25 is provided on the upstream side of the inlet purge chamber 24, that is, on the left side in FIG. On the other hand, an outlet purge chamber 26 is provided in the vicinity of the outlet portion 23 b of the muffle 23. A carry-out portion 27 is provided on the rear side of the outlet purge chamber 26, that is, on the right side in FIG.
[0038]
Inside the muffle 23, a part of an endless and mesh-like conveyor belt 31 is laid so as to extend along the longitudinal direction of the muffle 23. A conveyor drive unit including a motor 32 and a plurality of pulleys 33 is disposed below the rear end side of the muffle 23. The conveyor belt 31 is wound around each pulley 33. When the motor 32 is driven, the conveyor belt 31 moves from the inlet 23a toward the outlet 23b, that is, from the left side to the right side in FIG. The conveyor belt 31 is exposed at the carry-in unit 25 and the carry-out unit 27. Therefore, the workpiece W1 (silicon carbide molded body M1 and jig G1) can be placed horizontally on the conveyor belt 31 in the carry-in portion 25. Further, the work W1 can be removed from the conveyor belt 31 at the carry-out portion 27. In the present embodiment, the conveyor belt 31, the motor 32, and the pulley 33 constitute a conveying means for conveying the silicon carbide molded body M1 from the inlet portion 23a toward the outlet portion 23b.
[0039]
A portion of the muffle 23 excluding the rear end portion is surrounded by a rectangular tubular heat insulating material 34. A heater 35 as a heating means is installed inside the heat insulating material 34. The heater 35 is for heating the silicon carbide molded body M1 moving in the muffle 23 to a degreasing temperature. A cooling jacket 36 as a cooling means is disposed at the rear end of the muffle 23. The cooling jacket 36 is for cooling the heated workpiece to room temperature.
[0040]
As shown in FIG. 1B, the portion surrounded by the heat insulating material 34 in the muffle 23 is equally divided into 11 regions for convenience. Here, the first, second, third,... Eleventh regions are set in order from the left side of FIG. In the present embodiment, the first to fourth regions are assigned to the temperature raising zone Z1, the fifth to tenth regions are assigned to the soaking zone Z2, and the eleventh region is assigned to the slow cooling zone Z3. In FIG. 1B, the place where the cooling jacket 36 is provided is shown as a cooling zone Z4.
[0041]
As shown in FIG. 4, the muffle 23 of the present embodiment has a flat cross-sectional shape. The ceiling portion 23c of the muffle 23 is formed in an arc shape with a small curvature. Since the circular arc is convex upward, a portion corresponding to a position directly above the center line of the conveyor belt 31 is highest in the ceiling portion 23c. That is, the inner surface of the ceiling portion 23c is a non-horizontal plane.
[0042]
When jig G1 is placed on conveyor belt 31, silicon carbide molded body M1 is placed horizontally on jig G1 in a state perpendicular to the traveling direction (longitudinal direction of conveyor belt 31). At this time, both end surfaces of the silicon carbide molded body M1 are in a state of facing the side wall 23d of the muffle 23. Since the mounting surface of jig G1 is provided with a rib, a certain gap is ensured between the surface facing downward and the mounting surface in silicon carbide molded body M1. .
[0043]
The cooling zone Z4 on the rear end side of the muffle 23 is set to have a smaller cross-sectional area than the heating zone in the muffle 23 (that is, the temperature raising zone Z1, the soaking zone Z2, and the slow cooling zone Z3). In other words, the rear end side of the muffle 23 is narrowed.
[0044]
Specifically, the cross-sectional area of the heating zone in the muffle 23 when the work is charged is 0.1 m.²Below, preferably 0.09m²It may be set to the following. Further, the cross-sectional area of the heating zone in the muffle 23 when the workpiece is not charged is 0.07 m.²Below, preferably 0.05m²It may be set to the following. The reason is that if the sectional area of the heating zone is small, the flow velocity of the gas in the muffle 23 can be relatively easily increased.
[0045]
The continuous degreasing furnace 21 of this embodiment includes a gas introduction means 41 that introduces a gas having a low oxygen concentration into the muffle 23. The gas introduction means 41 includes a pipe 42 connected to a gas supply source (not shown) and a nozzle 43 provided at the tip of the pipe 42. The nozzles 43 are arranged so as to be paired on the left and right side walls 23d of the muffle 23. From these nozzles 43, low oxygen concentration gas (specifically, in this embodiment, air (air) and nitrogen (N₂) And gas mixture) are ejected laterally. As schematically shown in FIG. 4B, in this embodiment, the nozzles 43 are installed in all the first to eleventh regions.
[0046]
Here, the oxygen concentration in the gas is preferably set to 1% to 20%, preferably 5% to 10%, particularly preferably 7% to 10%.
If the oxygen concentration is lower than 1%, the decomposition reaction of the binder is difficult to proceed. As a result, the amount of residual coal increases and the strength decreases, and it takes a long time to sufficiently decompose the binder. This is because productivity decreases. On the contrary, if the oxygen concentration is higher than 20%, it is advantageous from the viewpoint of sufficiently decomposing the binder, but on the other hand, a large amount of flammable gas is generated, and as a result, the gas is easily ignited. Moreover, it is because there exists a possibility that intensity | strength reduction may be brought about as a result of compounds other than silicon carbide producing by oxidizing the silicon carbide in the silicon carbide molded object M1.
[0047]
The inert gas constituting the gas having a low oxygen concentration is preferably mainly nitrogen. This is because when nitrogen is used as the inert gas, it becomes easy to control the oxygen concentration and it is difficult to produce a compound that causes a decrease in strength.
[0048]
Moreover, the continuous degreasing furnace 21 of this embodiment is provided with the gas discharge means 46 which discharges | emits the said gas and the gas generated in the furnace out of the muffle 23. FIG. An ejector 48 for forcibly discharging the gas is provided at the end of the pipe 47 constituting the gas discharging means 46. In the present embodiment, a plurality of ejectors 48 are provided at different positions.
[0049]
As shown in FIG. 5A, the ejector 48 of the present embodiment supplies a main pipe portion 48b connected to a pipe 47, a nozzle portion 48a disposed in the main pipe portion 48b, and the nozzle portion 48a ejector air. An air introduction pipe 48c and the like are provided. The ejector air supplied through the air introduction pipe 48c is ejected from the nozzle portion 48a. As a result, an air flow from the lower side to the upper side in FIG. 5A is formed, and the gas on the muffle 23 side is sucked by this flow. On the other hand, the gas flowing into the pipe 47 side from the ejector 48 is deodorized by a deodorizing device (not shown) and then released to the atmosphere.
[0050]
As shown in FIG. 5B, the ejector 48 preferably includes a heater 49. In this figure, a sheathed heater 49 is wound around the main pipe portion 48b constituting the ejector 48 in order to reliably avoid the adhesion of tar T1 in the main pipe portion 48b. Accordingly, the main pipe portion 48b is heated by such a sheathed heater 49, so that the ejector 48 is prevented from being clogged and the discharge capacity is prevented from being lowered.
[0051]
The heating temperature by the heater 49 may be set to 200 ° C. or higher, preferably 250 ° C. or higher. This is because if the temperature in the main pipe portion 48b is lower than 200 ° C., the tar T1 may be condensed and adhere to the inner wall surface of the main pipe portion 48b. It is more preferable that a heater (not shown) is provided on the air introduction pipe 48c, and the air is heated to about 300 ° C. to 500 ° C. and then supplied to the nozzle portion 48a side. In addition, a heat insulating material 50 is disposed around the pipe 47 in order to reduce heat loss.
[0052]
  1 and 4As shown, the ejector 48 is provided in the second, third, fifth and sixth regions of the muffle 23. In other words, two ejectors 48 are provided in the temperature raising zone Z1, and further two in the soaking zone Z2. That is, the ejector 48 is provided not only in the low temperature region in the muffle 23 but also in the high temperature region.
[0053]
Then, the degreasing method at the time of using said continuous degreasing furnace 21 is described.
In the degreasing step, the silicon carbide molded body M1 needs to be heated to a temperature at which the binder can be decomposed, and is preferably heated to 200 ° C. to 600 ° C. depending on the type of the binder used. If the heating temperature at this time is too low, not only the productivity is lowered, but also the binder cannot be sufficiently decomposed and removed. Therefore, the amount of remaining carbon cannot be reduced, and it becomes difficult to achieve high strength of the honeycomb filter 1. On the other hand, if the heating temperature is too high, the loss of thermal energy increases and the cost performance decreases. Moreover, if it is attempted to raise the temperature to a high temperature in a short time, cracks and the like are generated, and there is a possibility that the achievement of high strength may be hindered. In consideration of the above circumstances, the degreasing temperature is set to 450 ° C. ± 10 ° C. in the present embodiment.
[0054]
The flash point of methanol, which is the main component of the generated gas, is 385 ° C. If the methanol concentration exceeds 6% by weight, which is the lower limit of explosion in an environment exceeding this temperature, methanol explodes in the muffle 23. There is a fear. For this reason, in this embodiment, the methanol concentration in the muffle 23 is managed so as to be a value considerably lower than the explosion limit lower limit value. Specifically, the methanol concentration is controlled so as not to exceed 1.5% by weight.
[0055]
Further, it is desirable that the temperature rising rate in the degreasing step is set to 5 ° C./min to 10 ° C./min, and the temperature decreasing rate is set to 8 ° C./min to 13 ° C./min. The conveyance speed of silicon carbide molded body M1 is desirably set to 45 mm / min to 60 mm / min.
[0056]
The flow rate of the gas flowing through the heating zone in the muffle 23 is preferably set to 500 mm / second or more, further 750 mm / second or more, and particularly 1000 mm / second or more. The reason is that the gas is less likely to stay in the muffle 23 by setting the flow velocity value large. Therefore, the gas can be reliably discharged out of the muffle 23 before being cooled and condensed by contact with the muffle 23. In the continuous degreasing furnace 21 of this embodiment, the flow rate is set by adjusting the discharge capacity of the ejector 48.
[0057]
[Examples and Comparative Examples]
(Production of Example 1)
Wet-mixing 51.5% by weight of α-type silicon carbide powder and 22% by weight of β-type silicon carbide powder, and adding 6.5% by weight and 20% by weight of organic binder (methylcellulose) and water to the resulting mixture, respectively. In addition, kneading. Next, a raw silicon carbide molded body M1 having a honeycomb structure was obtained by continuously extruding a kneaded product obtained by adding a small amount of a plasticizer and a lubricant and further kneading.
[0058]
Next, the moisture in the silicon carbide molded body M1 was evaporated by drying the silicon carbide molded body M1 in normal air (that is, in an oxygen atmosphere). Specifically, after drying for 3 minutes at 100 ° C. using a microwave dryer, drying was performed for 20 minutes at 110 ° C. using a hot air dryer. Furthermore, after the dried silicon carbide molded body M1 was cut, the through holes 12 of the silicon carbide molded body M1 were sealed with a sealing paste made of silicon carbide.
[0059]
Subsequently, the silicon carbide molded body M1 that had undergone the end surface sealing step was put into the continuous degreasing furnace 21 to perform degreasing. At this time, the temperature during degreasing (temperature in the soaking zone Z2) was set to 450 ° C. ± 10 ° C., and the keep time in the temperature range was set to about 70 minutes. Further, the temperature rising rate and the required time were set to 9.5 ° C./min, about 50 minutes, and the temperature decreasing rate and the required time were set to 10.5 ° C./min, about 29 minutes. Moreover, while the conveyance speed of the silicon carbide molded object M1 was set to 55 mm / min, the flow rate was set to 1068 mm / sec. In addition, the cross-sectional area of the heating zone in the muffle 23 when the work is charged is 0.09 m.²And the cross-sectional area when the workpiece is not inserted is 0.049m²Set to. Then, the oxygen concentration in the muffle 23 was set to 2% by appropriately changing the mixture ratio of the air-fuel mixture. Exhaust by the ejector 48 was performed at both the temperature raising zone Z1 and the soaking zone Z2.
[0060]
  After degreasing under the above conditions, the silicon carbide molded body M1 was taken out from the continuous degreasing furnace 21 and further set in a firing furnace. In this state, firing was performed at 2200 ° C. for about 3 hours in an atmospheric argon atmosphere. As a result, the honeycomb filter 1 of Example 1 was obtained.
(Example 25, Reference exampleAnd production of comparative examples)
  In Examples 2 to 5, by adjusting the discharge capacity of the ejector 48, the flow velocity of the gas flowing through the heating zone of the muffle 23 is set to 840 mm / second, 625 mm / second, 510 mm / second, and 405 mm / second, respectively. A degreasing process was performed. And the baking process similar to the above was performed after this. As a result, honeycomb filters 1 of Examples 2, 3, 4, and 5 were obtained.
[0061]
  Also,Reference exampleThen, while the gas flow rate was set to 1068 mm / second, the degreasing process was performed by exhausting only in the soaking zone Z2 (that is, only in the high temperature region). Then, by performing the same baking process as described above,Reference exampleThe honeycomb filter 1 was obtained.
[0062]
  In the comparative example, the degreasing step was performed by setting the gas flow rate to 405 mm / second and the oxygen concentration to 1% and exhausting only in the temperature raising zone Z1 (that is, only in the low temperature region). . And the honeycomb filter 1 of the comparative example was obtained by performing the same baking process as the above after this.
(Method and result of evaluation test)
  After the degreasing process, each silicon carbide molded body M1 was visually inspected with the naked eye. As a result, Examples 1 to5, Reference exampleIn any case, no adhesion of tar T1 was observed, and no cracks were observed. On the other hand, in the comparative example, the adhesion of tar T1 was recognized, and it was necessary to perform an operation for removing it after degreasing.
[0063]
Furthermore, when the residual carbon ratio (%) and the fracture strength (MPa) were measured by a conventionally known method after firing, the values shown in Table 1 below were obtained.
[0064]
[Table 1]

  Therefore, according to the example of the present embodiment, the following effects can be obtained.
[0065]
  (1) In the first to fifth embodiments, when the honeycomb filter 1 is manufactured by sequentially performing molding, drying, degreasing, and firing, exhaust is performed not only in the low temperature region but also in the high temperature region in the heating conveyance path of the continuous degreasing furnace 21. While degreasing. Also,Reference exampleThen, degreasing is performed while exhausting in a high temperature region in the heating conveyance path of the continuous degreasing furnace 21.
[0066]
Therefore, in each of the embodiments, the ejector 48 constituting the gas discharge means 46 is also provided in the high temperature region in the muffle 23. Therefore, since the temperature at the position where the ejector 48 is disposed becomes high, the gas can be discharged out of the muffle 23 before being condensed and causing condensation. Therefore, the problem of dripping and adhesion of tar T1 caused by condensation can be solved, and deterioration of quality and productivity due to the problem can be prevented.
[0067]
  That is, the product is not soiled by the tar T1 and the appearance is not deteriorated, and the quality in appearance is improved. Moreover, the operation | work which removes the attached tar T1 becomes unnecessary, and the fall of productivity is prevented. Moreover, the silicon carbide molded bodyM1As a result of the adhesion of tar T1 to the end surfaces 9a and 9b of the first and second ends, the sealing body 14 is prevented from falling off, and the quality in terms of strength is improved.
[0068]
The fired product obtained by each example is a honeycomb filter 1 having a residual carbon ratio of 0.2% or less, a fracture strength of 40 MPa or more, and end openings that are alternately sealed. Accordingly, the honeycomb filter 1 has not only low pressure loss and high filtering ability, but also extremely suitable performances such as being suitable for use at high temperature and being hardly damaged by thermal stress.
[0069]
  (2) Examples 1 to 4Reference exampleThen, since the flow velocity of the gas flowing through the heating zone is set to 500 mm / second or more, the gas is less likely to stay in the muffle 23. Accordingly, the gas can be reliably discharged out of the muffle 23 before being cooled by contact with the muffle 23 and causing condensation.
[0070]
(3) In each of the embodiments described above, a configuration in which the gas is forcibly discharged by the ejector 48 is employed. Therefore, the flow rate can be relatively easily increased and the flow rate can be controlled relatively easily.
[0071]
(4) In each of the above-described embodiments, the ejector 48 is heated by the heater 49, so that the gas passing therethrough is hardly cooled. As a result, the occurrence of condensation in the ejector 48 can be more reliably prevented. Therefore, clogging of the ejector 48 can be prevented, and a decrease in gas discharge capacity can be prevented beforehand.
[0072]
(5) In each of the above embodiments, the silicon carbide molded body M1 is heated to a temperature at which the organic binder can be decomposed in an atmosphere having an oxygen concentration of 1% to 20% during degreasing. Therefore, it is possible to obtain a degreased product excellent in quality and strength, and eventually a fired product excellent in quality and strength, without being accompanied by a decrease in productivity and ignition during degreasing.
[0073]
(6) In each said Example, degreasing is performed using the continuous degreasing furnace 21. FIG. For this reason, compared with the case where degreasing is performed in a batch type furnace, it is excellent in productivity in the first place.
(7) The gas introduction means 41 is configured to eject gas from the lateral direction in the muffle 23. Therefore, the gas can smoothly flow in each cell of the horizontally placed silicon carbide molded body M1 along the cell longitudinal direction. Therefore, gas can be reliably and efficiently supplied to the silicon carbide molded body M1, and uniform degreasing can be performed. This also leads to an improvement in quality in terms of strength.
[0074]
(8) The ceiling part 23c is an inclined surface inclined in the width direction. In other words, the ceiling part 23c is a non-horizontal plane. Therefore, even if the tar T1 is generated, the tar T1 flows along the inclined surface and flows in the width direction of the muffle 23. For this reason, tar T1 becomes difficult to hang down on a conveyance path, and adhesion of tar T1 can be prevented reliably.
[0075]
(9) The cross-sectional area of the outlet portion 23 b of the muffle 23 is smaller than the cross-sectional area of the central portion of the muffle 23. Therefore, it becomes easy to control the temperature in the muffle 23. In addition, as a result of heat becoming difficult to escape from the outlet portion 23b, heat loss is reduced and economic efficiency is improved.
[0076]
  The embodiment of the present invention may be modified as follows..
[0077]
-The ceiling part 23c of the muffle 23 is not limited to the cross-section arc shape like embodiment, For example, you may become the simple inclined surface which inclines in the width direction. Moreover, you may make the ceiling part 23c into a horizontal surface.
[0078]
-The exit part 23b of the muffle 23 does not need to be narrowed and may have the same cross-sectional area as the central part.
In place of the belt-type conveyor as in the embodiment, for example, a roller-type conveyor may be employed, and further, a conveying mechanism may be configured by employing something other than the conveyor mechanism.
[0079]
-You may degrease by mounting the silicon carbide molded object M1 on the conveyor belt 31 as it is, without using the jig | tool G1.
-As inert gas in degreasing, things other than nitrogen, for example, argon etc., can also be used.
[0080]
The heater 49 of the ejector 48 may be omitted if unnecessary.
In the continuous degreasing furnace 21, a plurality of muffles 23 may be arranged in parallel.
[0081]
The gas discharge means 46 may not use the ejector 48. That is, the gas discharge means 46 does not have to forcibly discharge the gas.
-In embodiment, the manufacturing method of the porous silicon carbide sintered compact of this invention was actualized as a manufacturing method of the honey-comb filter 1 for exhaust-gas purification apparatuses attached to a diesel engine.
[0082]
Of course, the method for producing a porous silicon carbide sintered body of the present invention is embodied as a method for producing a non-honeycomb ceramic filter, or as a method for producing something other than a filter (for example, a member for a heat exchanger). It is also possible.
[0083]
-In the said embodiment, the example which degreases the silicon carbide molded object M1 using the continuous degreasing furnace 21 of this invention was shown. However, the continuous degreasing furnace 21 can also be used for degreasing a molded body made of a ceramic material other than silicon carbide.
[0084]
Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below together with their effects.
(1) A muffle having an inlet portion and an outlet portion at both ends, a conveying means for conveying the silicon carbide molded body from the inlet portion toward the outlet portion, and the silicon carbide molded body moving in the muffle can be degreased. A heating zone in the muffle in a continuous degreasing furnace comprising heating means for heating to a temperature, gas introducing means for introducing a low oxygen concentration gas into the muffle, and gas discharging means for discharging the gas out of the muffle. A continuous degreasing furnace characterized in that a flow rate of the gas flowing through the gas is set to 500 mm / second or more. Therefore, according to the invention described in this technical idea 1, since the gas flow rate is increased and the gas is exhausted before the dew condensation, there is less concern about the dripping and adhesion of the foreign matter generated by the dew condensation.
[0085]
(2) A muffle having an inlet portion and an outlet portion at both ends, a conveying means for conveying the silicon carbide molded body from the inlet portion toward the outlet portion, and the silicon carbide molded body moving in the muffle can be degreased. A heating zone in the muffle in a continuous degreasing furnace comprising heating means for heating to a temperature, gas introducing means for introducing a low oxygen concentration gas into the muffle, and gas discharging means for discharging the gas out of the muffle. The sectional area of 0.1m²A continuous degreasing furnace characterized by being set as follows. Therefore, according to the invention described in this technical idea 2, since the cross-sectional area of the heating zone is reduced, the flow velocity can be easily increased, so that there is less fear of dripping or adhering foreign matter caused by condensation. .
[0086]
(3) In any one of claims 1 to 4 and technical ideas 1 and 2, the gas introduction means is configured to eject the gas from a lateral direction in the muffle. Therefore, according to the invention described in the technical idea 3, for example, gas can be reliably and efficiently supplied to a horizontally disposed honeycomb structure.
[0087]
(4) In any one of claims 1 to 4 and technical ideas 1 to 3, the ceiling portion of the muffle is an inclined surface inclined in the width direction. Therefore, according to the invention described in this technical idea 4, even if a foreign matter is generated due to condensation, the foreign matter flows along the inclined surface in the width direction, so that it is difficult to hang down on the transport path.
[0088]
(5) In any one of claims 1 to 4 and technical ideas 1 to 4, the cross-sectional area of the outlet portion of the muffle is smaller than the cross-sectional area of the central portion of the muffle. Therefore, according to the invention described in this technical idea 5, in addition to facilitating temperature control, it becomes economical because heat loss is reduced.
[0089]
【The invention's effect】
As described above in detail, according to the inventions described in claims 1 to 4, it is possible to provide a continuous degreasing furnace capable of preventing deterioration in quality and productivity due to dripping and adhesion of foreign matter.
[0090]
  Claim 5, 6According to the invention described in (1), it is possible to provide a method for producing a porous silicon carbide sintered body capable of preventing deterioration in quality and productivity due to dripping and adhesion of foreign matter.
[Brief description of the drawings]
FIG. 1A is an overall front view of a continuous degreasing furnace according to an embodiment of the present invention, and FIG. 1B schematically shows the continuous degreasing furnace.
FIG. 2 is a schematic cross-sectional view taken along line BB in FIG.
FIG. 3 is a schematic cross-sectional view taken along the line AA in FIG.
4A is a cross-sectional view of the muffle according to the embodiment, and FIG. 4B is a schematic diagram for explaining an exhaust position in the muffle.
FIGS. 5A and 5B are cross-sectional views of a nozzle portion of a gas discharge unit.
FIG. 6 is a perspective view of a honeycomb filter.
FIG. 7 is a partially broken cross-sectional view of a honeycomb filter.
8A is a cross-sectional view of a muffle previously proposed by the inventor of the present application, and FIG. 8B is a schematic view for explaining an exhaust position in the muffle.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Honeycomb filter as porous silicon carbide sintered compact, 21 ... Continuous degreasing furnace, 23 ... Muffle, 23a ... Inlet part, 23b ... Outlet part, 31 ... Conveyor belt which comprises a conveying means, 32 ... Conveying means Motor constituting 33, pulley constituting conveying means, 35 ... heater as heating means, 41 ... gas introducing means, 46 ... gas discharging means, 48 ... ejector constituting gas discharging means, 49 ... heater, M1 ... carbonization Silicon molded body, Z2 ... soaking zone as a high temperature region.

Claims (6)

A muffle having an inlet portion and an outlet portion at both ends, a conveying means for conveying a silicon carbide molded body containing silicon carbide powder and an organic binder from the inlet portion toward the outlet portion, and the silicon carbide moving in the muffle Heating means for heating the compact to a degreasable temperature, gas introducing means for introducing a gas whose oxygen concentration is set to 1% to 20% in the muffle, and gas discharging means for discharging the gas outside the muffle with the door, heated zones in order toward the outlet side from the inlet side of said muffle, soaking zone, a continuous degreasing furnace annealing zone is provided, the muffle said gas introducing means heating zones of the inner, soaking zone, is provided on all slow cooling zone, provided with the gas discharge means for raising the temperature zone and the soaking zone in the muffle, 200 ° C. the temperature of the soaking zone Continuous degreasing furnace 600 ° C. of the organic binder is characterized by being set to a temperature that can decompose. Continuous degreasing furnace according to claim 1, characterized in that setting the flow velocity of the gas flowing through the inside muffle than 500 mm / sec.   The continuous degreasing furnace according to claim 1 or 2, wherein the gas discharging means includes an ejector for forcibly discharging the gas.   The continuous degreasing furnace according to claim 3, wherein the ejector includes a heater. After molding a silicon carbide molded body containing silicon carbide powder and an organic binder, in the muffle provided with a heating step, a soaking zone , and a slow cooling zone in order from the drying step toward the outlet side from the inlet side Porous carbonization is performed by sequentially performing a degreasing step and a firing step in a continuous degreasing furnace maintained in a low oxygen concentration atmosphere by introducing a gas whose oxygen concentration is set to 1% to 20% from the gas introducing means. A method for producing a silicon sintered body, comprising:
A gas is introduced from the gas introduction means provided in all of the heating zone, soaking zone, and slow cooling zone in the muffle in the heating and conveying path of the continuous degreasing furnace, and the heating zone and soaking in the muffle are introduced. Degassing by setting the temperature of the soaking zone to a temperature at which the organic binder at 200 ° C. to 600 ° C. can be decomposed while exhausting the gas from the gas exhaust means provided in the zone to the outside of the muffle. A method for producing a porous porous silicon carbide sintered body. Method for producing a porous silicon carbide sintered body according to claim 5, characterized in that the degreasing by setting the flow rate of the gas flowing through the inside muffle than 500 mm / sec.

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