JPH0656530A - Production of high temperature type silicon carbide-based heating element - Google Patents
Production of high temperature type silicon carbide-based heating elementInfo
- Publication number
- JPH0656530A JPH0656530A JP4251804A JP25180492A JPH0656530A JP H0656530 A JPH0656530 A JP H0656530A JP 4251804 A JP4251804 A JP 4251804A JP 25180492 A JP25180492 A JP 25180492A JP H0656530 A JPH0656530 A JP H0656530A
- Authority
- JP
- Japan
- Prior art keywords
- silicon carbide
- heating element
- high temperature
- based heating
- vacuum
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000010438 heat treatment Methods 0.000 title claims abstract description 49
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 29
- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 25
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 239000002245 particle Substances 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 7
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims description 2
- 238000000465 moulding Methods 0.000 claims 2
- 239000012298 atmosphere Substances 0.000 abstract description 8
- 238000006243 chemical reaction Methods 0.000 abstract description 8
- 230000003647 oxidation Effects 0.000 abstract description 6
- 238000007254 oxidation reaction Methods 0.000 abstract description 6
- 230000005484 gravity Effects 0.000 abstract description 2
- 239000007858 starting material Substances 0.000 abstract 1
- 230000001590 oxidative effect Effects 0.000 description 6
- 238000005245 sintering Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- 230000002159 abnormal effect Effects 0.000 description 2
- YXTPWUNVHCYOSP-UHFFFAOYSA-N bis($l^{2}-silanylidene)molybdenum Chemical compound [Si]=[Mo]=[Si] YXTPWUNVHCYOSP-UHFFFAOYSA-N 0.000 description 2
- NFYLSJDPENHSBT-UHFFFAOYSA-N chromium(3+);lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Cr+3].[La+3] NFYLSJDPENHSBT-UHFFFAOYSA-N 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010304 firing Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910021343 molybdenum disilicide Inorganic materials 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910021431 alpha silicon carbide Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Ceramic Products (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、１７００℃近傍まで加
熱できる高温型炭化珪素質発熱体に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high temperature type silicon carbide heating element capable of heating up to around 1700 ° C.
【０００２】[0002]
【従来の技術】従来、炭化珪素質発熱体はセラミックス
発熱体の中でも、抵抗値が適当であること。他に比べ価
格的にも安価なことから各種分野で広く利用されてい
る。たとえば、金属の熱処理やセラミックス製品の焼成
等、酸化雰囲気中１２００〜１５００℃で加熱焼成する
場合はほとんど炭化珪素質発熱体が使用されている。し
かし、炭化珪素質発熱体はその製造方法から多孔質であ
り、１６００℃以上の高温領域では酸化が著しく、短命
であった。一方、１６００℃以上の酸化雰囲気中で使用
できるセラミックス質発熱体としては二珪化モリブデン
質発熱体やランタンクロマイト発熱体がある。しかし、
これらの発熱体もそれぞれ欠点があった。例えば二珪化
モリブデン質発熱体は高温域で軟化することや常温域で
脆いなど使いづらい点があった。また、抵抗が低いので
設備容量を大きくする必要があり、コストが高くつくこ
とが問題であった。またランタンクロマイト発熱体は、
抵抗値は炭化珪素質発熱体と同程度であるが昇温時の抵
抗変化が急激なため調整が難しいこと。高温で成分であ
る酸化クロムが揮発する等使いづらい欠点があった。2. Description of the Related Art Conventionally, a silicon carbide heating element has an appropriate resistance value among ceramic heating elements. It is widely used in various fields because it is cheaper than others. For example, in the case of heating and firing at 1200 to 1500 ° C. in an oxidizing atmosphere such as heat treatment of metals and firing of ceramic products, a silicon carbide type heating element is mostly used. However, the silicon carbide type heating element is porous due to its manufacturing method, and is remarkably oxidized in a high temperature region of 1600 ° C. or higher and has a short life. On the other hand, examples of ceramic heating elements that can be used in an oxidizing atmosphere at 1600 ° C. or higher include molybdenum disilicide heating elements and lanthanum chromite heating elements. But,
Each of these heating elements also had drawbacks. For example, molybdenum disilicide-based heating elements are difficult to use, such as softening at high temperature and brittleness at room temperature. Further, since the resistance is low, it is necessary to increase the equipment capacity, which causes a problem of high cost. The lanthanum chromite heating element
The resistance value is about the same as that of the silicon carbide heating element, but it is difficult to adjust because the resistance changes rapidly when the temperature rises. There was a drawback that it was difficult to use, such as the volatilization of the component chromium oxide at high temperatures.
【０００３】[0003]
【発明が解決しようとする課題】上記で説明したよう
に、いずれの発熱体もある程度の効果はあるが、コス
ト、操作性に難があり、こうした点ですぐれる炭化珪素
質発熱体の高温での寿命特性の改善が望まれていた。As described above, all the heating elements have some effect, but they are difficult in terms of cost and operability, and are excellent in this respect at the high temperature of the silicon carbide heating element. It was desired to improve the life characteristics of the.
【０００４】[0004]
【課題を解決するための手段】すなわち本発明は、高温
型炭化珪素質発熱体の製造方法において、原料粉末とし
て粒子径３〜１５μｍの炭素粉末と粒子径１０〜５０μ
ｍの炭化珪素粉末とを混合し、加圧成形により理論成形
密度の９２〜９８％の成形体を作る工程と該成形体を窒
素雰囲気中２０００℃以上で珪化する工程と該珪化体を
真空度１０−１ｔｏｒｒ以下、処理温度１６００〜２０
００℃にて加熱処理を行う工程からなることを特徴とす
る。上記の窒素雰囲気中の反応焼結は二次的なＳｉＣの
合成だけでなく、ＳｉＣにＮ２をドープさせ、所定の抵
抗を得る目的がある。ここで原料の粒度を炭素粉末１０
〜１５μｍおよび炭化珪素１０〜５０μｍとしたのはこ
の範囲をはずれると理論成形密度の９２〜９８％の成形
体が得られず、この場合、遊離の炭素や遊離Ｓｉが過剰
に焼結体中に残留し、目的の高温型炭化珪素質発熱体が
得られないためである。また、反応焼結において、窒素
雰囲気中２０００℃以上で行うとしたのは、２０００℃
未満では反応焼結が十分進まず、未反応部分が生じ、焼
結体の特性が劣るためである。さらに、真空加熱処理工
程において真空度を１０−１ｔｏｒｒ以下の高真空、処
理温度を１６００〜２０００℃としたのは、これ以外の
条件ではやはり焼結体の密度が上がらずとくに高温での
耐酸化特性が劣るためである。なお、真空加熱処理の後
さらに窒素をドープする工程を付加することによって抵
抗値や抵抗温度特性などを変更することも可能である。
また、本発明に係る発熱体は耐酸化特性を向上させたも
のであるが、非酸化雰囲気中での使用でも十分な耐熱性
を具備しており、用途は、酸化雰囲気中に限定されな
い。That is, according to the present invention, in a method for producing a high temperature silicon carbide heating element, a carbon powder having a particle diameter of 3 to 15 μm and a particle diameter of 10 to 50 μm are used as raw material powders.
m silicon carbide powder is mixed and pressure-molded to form a molded body of 92 to 98% of theoretical molded density, a step of silicifying the molded body in a nitrogen atmosphere at 2000 ° C. or higher, and a degree of vacuum of the silicified body. 10 -1 torr or less, processing temperature 1600 to 20
It is characterized by comprising a step of performing heat treatment at 00 ° C. The reaction sintering in the nitrogen atmosphere described above is intended not only for secondary synthesis of SiC, but also for doping SiC with N 2 to obtain a predetermined resistance. Here, the particle size of the raw material is 10 carbon powder.
.About.15 .mu.m and 10 to 50 .mu.m of silicon carbide do not yield a molded body of 92 to 98% of the theoretical compacted density outside this range. In this case, free carbon and free Si are excessive in the sintered body. This is because it remains and the intended high temperature type silicon carbide heating element cannot be obtained. In addition, the reaction sintering is performed at 2000 ° C. or higher in a nitrogen atmosphere at 2000 ° C.
If it is less than the above, the reaction sintering does not proceed sufficiently, an unreacted portion is generated, and the characteristics of the sintered body are inferior. Further, in the vacuum heat treatment step, the degree of vacuum is set to a high vacuum of 10 −1 torr or less and the treatment temperature is set to 1600 to 2000 ° C. The reason is that the density of the sintered body does not increase under other conditions, and the acid resistance is particularly high. This is because the conversion characteristics are inferior. It is also possible to change the resistance value, resistance temperature characteristic, etc. by adding a step of doping nitrogen after the vacuum heat treatment.
Further, although the heating element according to the present invention has improved oxidation resistance, it has sufficient heat resistance even when used in a non-oxidizing atmosphere, and its use is not limited to an oxidizing atmosphere.
【０００５】[0005]
【作用】本発明において、真空加熱処理工程について詳
細に説明する。まず第一に真空度１０−１ｔｏｒｒ以下
の高真空で加熱処理することは、反応焼結体中に残った
Ｓｉを除去することを目的としている。発熱体としてＳ
ｉを残すと低抵抗となるばかりか抵抗温度係数も負とな
って発熱体として使用が困難となる。残ったＳｉを除去
するためには、例えば大気圧、非酸化性雰囲気中で２０
００℃の高温で加熱処理方法があるが、その場合Ｓｉは
除去できるが構成するＳｉＣ粒子が異常粒成長を起こし
緻密な組織とならず組織が弱くなる。このような場合、
発熱体として使用すると酸化が内部まで進行し、長寿命
化は図れない。第二の目的としては、上記のように気孔
の制御にある。気孔が大きくなると耐酸化性に劣るた
め、ＳｉＣの異常粒成長を押さえ、緻密な組織にするこ
とが必要である。このため、真空加熱処理によりＳｉＣ
の粒子成長をおさえ気孔を調整することが耐酸化性に対
して大きな効果を示す。この結果、発熱体として使用中
非常に緻密なＳｉＯ２の保護膜が形成され、酸素が内部
まで拡散せず、酸化雰囲気中で良好な耐久性を示すもの
である。In the present invention, the vacuum heat treatment step will be described in detail. First of all, the heat treatment at a high vacuum of a vacuum degree of 10 −1 torr or less is intended to remove Si remaining in the reaction sintered body. S as a heating element
If i is left, the resistance becomes low and the temperature coefficient of resistance becomes negative, which makes it difficult to use as a heating element. In order to remove the remaining Si, for example, at atmospheric pressure, in a non-oxidizing atmosphere, 20
There is a heat treatment method at a high temperature of 00 ° C. In that case, Si can be removed, but the constituent SiC particles cause abnormal grain growth, and the structure does not become a dense structure and the structure becomes weak. In such cases,
If it is used as a heating element, oxidation will proceed to the inside and the life cannot be extended. The second purpose is to control the pores as described above. Since the oxidation resistance deteriorates when the pores become large, it is necessary to suppress abnormal grain growth of SiC and form a dense structure. For this reason, the
Controlling particle growth and controlling pores have a great effect on oxidation resistance. As a result, a very dense protective film of SiO 2 is formed during use as a heating element, oxygen does not diffuse to the inside, and good durability is exhibited in an oxidizing atmosphere.
【０００６】[0006]
【実施例】本発明を実施例をもとに説明する。炭素粉末
として、黒鉛粉末（粒子径５〜１３μｍ）３０重量％と
炭化珪素粉末として、α−ＳｉＣ（粒子径２０〜５０μ
ｍ）７０重量％に一般的なセルロース系バインダーを数
％と水を添加し、混合し、加圧プレスで所定の形状に成
形した。得られた成形体の寸法は、外径２０ｍｍ、内径
１０ｍｍ、長さ３００ｍｍの管状であって、理論成形密
度の９５％であった。得られた成形体を電気炉で窒素ガ
ス雰囲気中、処理温度２２００℃で反応焼結させた。反
応焼結体の物理特性は、かさ比重３．１１、焼結体中の
遊離Ｓｉは５重量％であった。つぎに該焼結体を真空焼
結炉で真空度３×１０−４ｔｏｒｒ、処理温度１７００
℃で２時間処理し、炭化珪素質発熱体を得た。比較のた
め、従来の方法によって再結晶質炭化珪素質発熱体を製
作し、上記と同寸法の発熱体を得た。両者の特性を表１
に示した。さらに本発明の発熱体と従来法による再結晶
質炭化珪素質発熱体の寿命比較のために以下のテストを
行なった。本発明の発熱体と従来法による再結晶質炭化
珪素質発熱体を炉内寸法２００ｍｍ×２００ｍｍ×３０
０ｍｍの電気炉に各２本づつ設置し、発熱させて炉内温
度１６５０℃で保持した。連続１０００時間通電したの
ちの発熱体の抵抗増加率を測定した結果を表１に示し
た。EXAMPLES The present invention will be described based on examples. Graphite powder (particle size 5 to 13 μm) 30% by weight as carbon powder and α-SiC (particle size 20 to 50 μm) as silicon carbide powder.
m) A few% of a general cellulosic binder and water were added to 70% by weight, mixed, and molded into a predetermined shape by a pressure press. The obtained molded product had a tubular shape with an outer diameter of 20 mm, an inner diameter of 10 mm and a length of 300 mm, and was 95% of the theoretical molded density. The obtained molded body was subjected to reaction sintering in an electric furnace in a nitrogen gas atmosphere at a treatment temperature of 2200 ° C. As for the physical properties of the reaction sintered body, the bulk specific gravity was 3.11, and free Si in the sintered body was 5% by weight. Next, the sintered body was vacuumed in a vacuum sintering furnace at a vacuum degree of 3 × 10 −4 torr and a processing temperature of 1700.
It was treated at 0 ° C. for 2 hours to obtain a silicon carbide heating element. For comparison, a recrystallized silicon carbide heating element was manufactured by a conventional method to obtain a heating element having the same size as the above. Table 1 shows the characteristics of both
It was shown to. Further, the following tests were carried out to compare the lives of the heating element of the present invention and the conventional recrystallized silicon carbide heating element. The heating element of the present invention and the recrystallized silicon carbide heating element according to the conventional method were used to measure the inside dimensions of the furnace 200 mm × 200 mm × 30
Two of each were installed in a 0 mm electric furnace, and heat was generated to maintain the furnace temperature at 1650 ° C. Table 1 shows the results of measuring the resistance increase rate of the heating element after continuous energization for 1000 hours.
【０００７】[0007]
【表１】 [Table 1]
【０００８】[0008]
【発明の効果】実施例で明らかなように本発明の炭化珪
素質発熱体の製造方法によれば従来の炭化珪素質発熱体
では困難であった１６００℃以上の高温域で十分な耐酸
化性をもち、実用に耐える発熱体が得られることがわか
った。これによって従来の高温発熱体では達成できなか
ったコストと操作性のよさで炭化珪素質発熱体の応用分
野が広がることが期待できる。As is apparent from the examples, according to the method for manufacturing a silicon carbide based heating element of the present invention, sufficient oxidation resistance is achieved at a high temperature range of 1600 ° C. or higher, which was difficult with the conventional silicon carbide based heating element. It has been found that a heating element having a heat resistance of practical use can be obtained. As a result, it is expected that the field of application of the silicon carbide based heating element will be expanded due to its cost and operability that could not be achieved with conventional high temperature heating elements.
Claims (1)
いて、原料粉末として粒子径３〜１５μｍの炭素粉末と
粒子径１０〜５０μｍの炭化珪素粉末とを混合し、加圧
成形により理論成形密度の９２〜９８％の成形体を作る
工程と該成形体を窒素雰囲気中２０００℃以上で珪化す
る工程と該珪化体を真空度１０−１ｔｏｒｒ以下、処理
温度１６００〜２０００℃にて加熱処理を行う工程から
なることを特徴とする高温型炭化珪素質発熱体の製造方
法。1. A method for producing a high temperature silicon carbide heating element, wherein carbon powder having a particle diameter of 3 to 15 μm and silicon carbide powder having a particle diameter of 10 to 50 μm are mixed as a raw material powder, and the theoretical molding density is obtained by pressure molding. Of 92 to 98%, a step of silicifying the molded body in a nitrogen atmosphere at 2000 ° C. or higher, and a heat treatment of the silicified body at a vacuum degree of 10 −1 torr or less at a treatment temperature of 1600 to 2000 ° C. A method of manufacturing a high temperature silicon carbide heating element, comprising the steps of:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25180492A JP3277295B2 (en) | 1992-08-07 | 1992-08-07 | Method for producing high-temperature silicon carbide heating element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25180492A JP3277295B2 (en) | 1992-08-07 | 1992-08-07 | Method for producing high-temperature silicon carbide heating element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0656530A true JPH0656530A (en) | 1994-03-01 |
| JP3277295B2 JP3277295B2 (en) | 2002-04-22 |
Family
ID=17228176
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25180492A Expired - Fee Related JP3277295B2 (en) | 1992-08-07 | 1992-08-07 | Method for producing high-temperature silicon carbide heating element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3277295B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115012028A (en) * | 2022-07-01 | 2022-09-06 | 山西中电科新能源技术有限公司 | Method for preparing large-size silicon carbide crystals |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101406420B1 (en) | 2008-07-17 | 2014-06-13 | 엘지전자 주식회사 | Silicon carbide heating element and manufacturing method thereof |
-
1992
- 1992-08-07 JP JP25180492A patent/JP3277295B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115012028A (en) * | 2022-07-01 | 2022-09-06 | 山西中电科新能源技术有限公司 | Method for preparing large-size silicon carbide crystals |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3277295B2 (en) | 2002-04-22 |
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