JPH01166481A - Sheathed heater - Google Patents
Sheathed heaterInfo
- Publication number
- JPH01166481A JPH01166481A JP32584687A JP32584687A JPH01166481A JP H01166481 A JPH01166481 A JP H01166481A JP 32584687 A JP32584687 A JP 32584687A JP 32584687 A JP32584687 A JP 32584687A JP H01166481 A JPH01166481 A JP H01166481A
- Authority
- JP
- Japan
- Prior art keywords
- silica sol
- powder
- insulation resistance
- silica
- added
- 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.)
- Pending
Links
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims abstract description 84
- 239000000395 magnesium oxide Substances 0.000 claims abstract description 42
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 32
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims abstract description 28
- 239000000843 powder Substances 0.000 claims abstract description 23
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 16
- 239000000203 mixture Substances 0.000 claims description 2
- 238000009413 insulation Methods 0.000 abstract description 26
- 238000010438 heat treatment Methods 0.000 abstract description 19
- 239000004065 semiconductor Substances 0.000 abstract description 8
- 238000010292 electrical insulation Methods 0.000 abstract description 5
- 238000000034 method Methods 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- 238000006243 chemical reaction Methods 0.000 abstract 1
- 239000004615 ingredient Substances 0.000 abstract 1
- 230000000452 restraining effect Effects 0.000 abstract 1
- 229910052751 metal Inorganic materials 0.000 description 8
- 239000002184 metal Substances 0.000 description 8
- 239000012535 impurity Substances 0.000 description 5
- 239000013078 crystal Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 229910001220 stainless steel Inorganic materials 0.000 description 3
- 239000010935 stainless steel Substances 0.000 description 3
- 238000010411 cooking Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 1
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 235000014380 magnesium carbonate Nutrition 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910001120 nichrome Inorganic materials 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000013535 sea water Substances 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 229910000601 superalloy Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、一般調理器具や暖房器具などの幅広い製品分
野における加熱源として応用されるシーズヒータに関し
、特に通電時の電気絶縁特性に優れた信頼性の高いシー
ズヒータに関するものである。[Detailed Description of the Invention] Industrial Application Field The present invention relates to a sheathed heater that is applied as a heating source in a wide range of product fields such as general cooking appliances and heating appliances, and in particular has excellent reliability in electrical insulation properties when energized. This relates to a sheathed heater with high performance.
従来の技術
従来よりシーズヒータは簡便であると共に、安全性が高
く、かつ耐食性に優れているため、オープン、電子レン
ジ、電気コンロ、電気ストーブ等、調理および暖房器具
の加熱源として幅広く使用されている。Conventional technology Since sheathed heaters are simple, safe, and have excellent corrosion resistance, they have been widely used as a heating source for cooking and heating appliances such as open ovens, microwave ovens, electric stoves, and electric stoves. There is.
このシーズヒータは、一般に、両端に端子棒を備えたコ
イル状の電熱線を金属パイプの中央部に挿入し、この金
属パイプに電気絶縁粉末を充填した後、圧延減径し、所
定の形状に曲げ加工して製造される。This sheathed heater generally involves inserting a coiled heating wire with terminal bars at both ends into the center of a metal pipe, filling the metal pipe with electrical insulating powder, and then rolling it to a predetermined shape. Manufactured by bending.
このようなシーズヒータの電気絶縁粉末として従来より
電融マグネシアが用いられてきた。Electrofused magnesia has conventionally been used as an electrically insulating powder for such sheathed heaters.
これは電融マグネシアが電気絶縁性、熱伝導性に優れ、
また商業的に安価で、かつ安定して供給されているため
であった。This is because fused magnesia has excellent electrical insulation and thermal conductivity.
This is also because it is commercially inexpensive and stably supplied.
発明が解決しようとする問題点
シーズヒータには前述したように電気絶縁粉末として電
融マグネシアが用いられてきた。この電融マグネシアの
絶縁抵抗は温度上昇と共に低下、半導体的性質を示す。Problems to be Solved by the Invention As mentioned above, fused magnesia has been used as an electrically insulating powder in sheathed heaters. The insulation resistance of this fused magnesia decreases as the temperature rises, exhibiting semiconducting properties.
その関係は一般に次式で表わされる。The relationship is generally expressed by the following equation.
ここでρは固有抵抗、Ｅは活性化エネルギー、Ｔは絶対
温度、ｋは゛ポルツマン定数、Ａは定数である。Here, ρ is a specific resistance, E is an activation energy, T is an absolute temperature, k is a Portzmann constant, and A is a constant.
従って、電融マグネシアの絶縁抵抗はＡ及びΣによって
決まり、それぞれの値によって低温用から高温用のグレ
ードに分類される。Therefore, the insulation resistance of fused magnesia is determined by A and Σ, and grades are classified from low-temperature grade to high-temperature grade depending on each value.
１０００℃における固有抵抗は、低温用で１０６Ω儒程
度、高温用で１０７〜１０８Ω譚程度であるが、最近の
加熱温度の高温化や形状の短小化等の要望を満たすため
には、これらの絶縁抵抗では不十分であった。The specific resistance at 1000°C is about 106 Ω for low temperature applications and 107 to 108 Ω for high temperature applications, but in order to meet the recent demands for higher heating temperatures and shorter and smaller shapes, these insulation Resistance was not enough.
一方、単結晶マグネシアは１ｏｏｏ℃で１０Ωα砒、の
固有抵抗を示すが、コスト的には通常の電融マグネシア
の約１ｏｏＯ倍の価格であり、非常に高価でシーズヒー
タへの適用は難しかった。On the other hand, single-crystal magnesia exhibits a specific resistance of 10 Ωα arsenic at 100° C., but it is about 100 times as expensive as ordinary fused magnesia, making it extremely expensive and difficult to apply to sheathed heaters.
本発明は前述した問題点を解決するもので、高い絶縁抵
抗を有する安価なシーズヒータを提供することを目的と
するものである。The present invention solves the above-mentioned problems, and aims to provide an inexpensive sheathed heater with high insulation resistance.
問題点を解決するための手段
上記問題点を解決するために本発明は、電気絶縁粉末と
して、電融マグネシア粉末を使用し、シリカゾルをシリ
カ重量に換算して０，３〜１５ｗｔ％添加し、４５０℃
以上の温度で加熱処理したものである。Means for Solving the Problems In order to solve the above problems, the present invention uses fused magnesia powder as the electrical insulating powder, adds 0.3 to 15 wt% of silica sol in terms of silica weight, 450℃
It was heat-treated at the above temperature.
作 用
シーズヒータの電気絶縁粉末に使用される電融マグネシ
アは一般に不純物を含有している。これらの不純物は１
価のアルカリ金属酸化物であるＮａ２ｏ＋に２０．２価
のアルカリ土類金属酸化物であるＣａＯ１’３価の酸化
物であるＦｅ２Ｏ３やＡｔ２０３、Ｂ２Ｏ２，４価の酸
化物であル５１０２ヤｚｘ０２等カ主なものである。こ
れらの不純物の混入は、電融マグネシアの原材料が天然
マグネサイトや海水マグネシアクリンカであることから
不可避であるが、２価のＭｇＯ中に１価や３価、４価の
酸化物やイオン半径の異なる２価の酸化物が不純物とし
て混入することにより、結晶内に欠陥を生じて半導体的
性質を付与する結果、絶縁抵抗が単結晶マグネシアに比
べて大きく低下することになる。通常、電融マグネシア
はｐ型の半導体としての性質を有し、Ｍｑと０の比は、
０が過剰でＭｑが不足していると考えられている。Function The fused magnesia used in the electrically insulating powder of sheathed heaters generally contains impurities. These impurities are 1
Na2O+ which is a valent alkali metal oxide, CaO1 which is a divalent alkaline earth metal oxide, Fe2O3 which is a trivalent oxide, At203, B2O2, etc. This is the main thing. The contamination of these impurities is unavoidable because the raw materials for fused magnesia are natural magnesite and seawater magnesia clinker. The incorporation of different divalent oxides as impurities causes defects in the crystal and imparts semiconductor properties, resulting in a greatly reduced insulation resistance compared to single-crystal magnesia. Normally, fused magnesia has properties as a p-type semiconductor, and the ratio of Mq to 0 is
It is thought that 0 is in excess and Mq is insufficient.
本発明では、この電融マグネシア粉末にシリカゾルを添
加して吸着させた後、４５０℃以上の温度で加熱処理し
て乾燥及び拡散処理することにより、電融マグネシア粉
末の表面及び内部を改質して半導体的性質を押さえ、絶
縁抵抗を高めることができるものである。In the present invention, after adding and adsorbing silica sol to the fused magnesia powder, the surface and interior of the fused magnesia powder are modified by heat treatment at a temperature of 450°C or higher, drying, and diffusion treatment. This makes it possible to suppress semiconducting properties and increase insulation resistance.
電融マグネシア粉末にシリカゾルを添加して吸着させる
工程としては、（１）粉末状態でシリカゾルを添加し、
４５０℃以上の温度で加熱処理を行なった後、金属パイ
プ内に充填してシーズヒータを形成する。（２） 金
属パイプ内に電融マグネシア粉末を充填した後、シリカ
ゾルを含浸し、圧延減径して４５０℃以上の温度で加熱
処理を行なってシーズヒータを形成する。（３）金属パ
イプ内に電融マグネシア粉末を充填し、圧延減径した後
、シリカゾルを含浸し、４５０℃以上の温度で加熱処理
を行なってシーズヒータを形成する等、シーズヒータの
加工工程中のいずれの段階で行なっても効果を有するも
のである。The process of adding silica sol to electrofused magnesia powder and adsorbing it is (1) adding silica sol in powder form,
After performing a heat treatment at a temperature of 450° C. or higher, the metal pipe is filled with the metal pipe to form a sheathed heater. (2) After filling a metal pipe with fused magnesia powder, it is impregnated with silica sol, rolled to reduce its diameter, and heated at a temperature of 450° C. or higher to form a sheathed heater. (3) During the manufacturing process of a sheathed heater, such as filling a metal pipe with fused magnesia powder, rolling it to reduce its diameter, impregnating it with silica sol, and performing heat treatment at a temperature of 450°C or higher to form a sheathed heater. It is effective even if it is performed at any stage.
シリカゾルの添加量は、用いる電融マグネシアの半導体
的性質の程度や不純物量によって異なり、添加量が少な
いとｐ型半導体となり、また添加量が多いとｎ型半導体
となって共に十分な絶縁抵抗が得られないが、一般にシ
リカ重量に換算して０．３〜１５ｗｔ％の範囲内で高い
絶縁抵抗を得ることができる。The amount of silica sol added varies depending on the degree of semiconducting properties of the electrofused magnesia used and the amount of impurities.If the amount added is small, it becomes a p-type semiconductor, and if the amount added is large, it becomes an n-type semiconductor, and both have sufficient insulation resistance. However, high insulation resistance can generally be obtained within the range of 0.3 to 15 wt% in terms of silica weight.
４５０℃以上の温度での加熱処理は、シリカゾルに含ま
れる水分を除去乾燥する目的と、シリカ成分を電融マグ
ネシア中に拡散する目的を有している。乾燥のためには
、化学吸着水を除去する必要があり４５０℃以上の温度
での加熱処理が必要となる。またシリカ成分の拡散につ
いては、電融マグネシアの内部まで十分に拡散させるた
めには９００℃以上の加熱処理が望ましい。従って加熱
処理の温度は、４５０℃以上、望ましくは９００℃以上
が必要である。The heat treatment at a temperature of 450° C. or higher has the purpose of removing moisture contained in the silica sol and drying it, and the purpose of diffusing the silica component into the fused magnesia. For drying, it is necessary to remove chemically adsorbed water, and heat treatment at a temperature of 450° C. or higher is required. Regarding the diffusion of the silica component, heat treatment at 900° C. or higher is desirable in order to sufficiently diffuse the silica component into the interior of the fused magnesia. Therefore, the temperature of the heat treatment needs to be 450°C or higher, preferably 900°C or higher.
実施例
以下、本発明の一実施例を第１図及び第２図にもとづい
て説明する。EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2.
まず、４０〜３２゛６メツシユに粉砕した電融マグネシ
アを、中心に直径３ｍ、長さ４０簡のステンレス棒を配
置した内径８ｍ、外径１０＋ｏ＋、長さ２０■のステン
レスパイプ内に充填し、シリカ含有量２０ｗｔ％ のシ
リカゾルを任意の量だけ添加して含浸させた後、１３０
ＫＰ／ｃｒＩの圧力でプレスレ、パイプ内の完全に充填
した。その後、パイプ及び中心のステンレス棒に直径０
．５ｍのニクロム線をスポット溶接し、絶縁測定用のリ
ード線とした。サンプルは電気炉内に投入し、１ｏＯｏ
℃で３０分の加熱処理を施した。比較のため、シリカゾ
ルを添加含浸しないサンプルも同様の処理を施した。First, fused magnesia crushed into 6 meshes of 40~32゛ was filled into a stainless steel pipe with an inner diameter of 8 m, an outer diameter of 10 + o +, and a length of 20 cm, with a stainless steel rod of 3 m in diameter and 40 pieces in length placed in the center. After adding a desired amount of silica sol with a silica content of 20 wt% and impregnating it,
Pressure was applied at a pressure of KP/crI to completely fill the pipe. After that, the pipe and the center stainless steel rod are made with a diameter of 0.
．． A 5 m long nichrome wire was spot welded and used as a lead wire for insulation measurement. The sample was placed in an electric furnace and heated to 1oOo.
A heat treatment was performed at ℃ for 30 minutes. For comparison, a sample that was not impregnated with silica sol was also subjected to the same treatment.
以上のようにして作製したサンプルを電気炉中に吊るし
、約１時間かけて１０００℃に昇温し、約１０分間保持
した後、ＤＣｌｏｏＶの絶縁計を用いて絶縁抵抗を測定
し、計算により固有抵抗を求めた。The sample prepared as described above was suspended in an electric furnace, heated to 1000°C over about 1 hour, and held for about 10 minutes. The insulation resistance was measured using a DClooV insulation meter, and the specific I asked for resistance.
２種の電融マグネシアを用いて測定を行なったが、用い
た電融マグネシアの組成を第１表に、得られた固有抵抗
と、シリカに換算したシリカゾルの添加量の関係を第１
図に示す。The measurements were carried out using two types of electrofused magnesia. The composition of the electrofused magnesia used is shown in Table 1, and the relationship between the obtained specific resistance and the amount of silica sol added in terms of silica is shown in Table 1.
As shown in the figure.
（以下４！Ｑ）
第１図から明らかなように、比較的高純度の電融マグネ
シアＡにおいては、シリカに換算したシリカゾルの添加
量が１．６〜３ｗｔ％で最大の固有抵抗を示し、さらに
添加量が増加すると逆に固有抵抗が低下した。一方、比
較的低純度の電融マグネシアＢにおいては、同様に４〜
５ｗｔ％ で最大の固有抵抗を示した。このことは、シ
リカゾルを添加した電融マグネシアの半導体的性質がｐ
型からｎ型へと添加量と共に変化することを意味してい
る。(4!Q below) As is clear from Figure 1, relatively high-purity electrofused magnesia A exhibits the maximum specific resistance when the amount of silica sol added is 1.6 to 3 wt% in terms of silica. Furthermore, as the amount added increased, the specific resistance decreased. On the other hand, in relatively low-purity electrofused magnesia B, similarly 4 to
The maximum resistivity was shown at 5wt%. This means that the semiconducting properties of fused magnesia to which silica sol has been added are p
This means that it changes from type to n-type with the amount added.
また、固有抵抗の改良度合は低純度の電融マグネシアＢ
において著しく、固有抵抗の最大値はほぼ同等の値とな
った。このことは半導体的性質をなくすことにより、一
定の固有抵抗が得られることを意味しており、工業的に
は比較的低コストの低純度マグネシアを用いることが可
能となシ、シーズヒータの材料コストを引き下げること
ができることを意味する。In addition, the degree of improvement in specific resistance is that of low-purity fused magnesia B.
Remarkably, the maximum values of resistivity were almost the same. This means that a certain specific resistance can be obtained by eliminating semiconductor properties, and it is possible to use relatively low-cost, low-purity magnesia industrially, which is a material for sheathed heaters. This means that costs can be reduced.
次に、同様に第１表に示した２種類の電融マグネシアを
用いてシーズヒータを作製した。両端に端子棒を備えた
コイ゛ル状の電熱線を耐食耐熱超合金ＮＣＦ３００から
なる金属パイプに挿入し、電気絶縁粉末として電融マグ
ネシア粉末を金属パイプ内に充填した後、シリカ含有量
２０ｗｔ％ のシリカゾルを任意の量だけ添加して含
浸させ、圧延減径を施し、最高温度１０５０℃のトンネ
ル炉で加熱処理し、さらにＵ字状に曲げ加工およびプレ
ス加工を施して、外径６．６＋＋ｍ、全長５００ｍｍの
Ｕ字状のシーズヒータを作製した。Next, sheathed heaters were similarly produced using the two types of fused magnesia shown in Table 1. A coiled heating wire with terminal rods at both ends was inserted into a metal pipe made of corrosion-resistant and heat-resistant superalloy NCF300, and after filling the metal pipe with fused magnesia powder as electrical insulating powder, the silica content was 20 wt%. A desired amount of silica sol was added and impregnated, the diameter was reduced by rolling, heat treated in a tunnel furnace with a maximum temperature of 1050°C, and further bent and pressed into a U-shape to form an outer diameter of 6.6++ m. A U-shaped sheathed heater with a total length of 500 mm was manufactured.
、 ｉＣＣクシスヒータを用いてＡＣｌｏＯｖ、４ｏ
。, ACloOv, 4o using iCC Kxis heater
.
Ｗで通電を行ない、６分後安定状態になった時点でＤＣ
５００Ｖの絶縁計を用いて絶縁抵抗を測定した。測定は
各条件ごとに５本のシーズヒータについて行なった。そ
して得られた絶縁抵抗と、シリカに換算したシリカゾル
の添加量の関係を第２図に示す。Turn on the current with W, and when it reaches a stable state after 6 minutes, turn on the DC
Insulation resistance was measured using a 500V insulation meter. Measurements were performed on five sheathed heaters under each condition. FIG. 2 shows the relationship between the obtained insulation resistance and the amount of silica sol added in terms of silica.
第２図から明らかなように、シーズヒータの絶縁抵抗と
シリカゾルの添加量の関係は、第１図に示した電融マグ
ネシアの固有抵抗とシリカゾルの添加量の関係と良い一
致を示した。電融マグネシアＡについては、シリカに換
算して２ｗｔ％ 前後のシリカゾルの添加で最大の絶縁
抵抗が得られ、電融マグネシアＢについては、同様に７
ｗｔ％前後のシリカゾルの添加で最大の絶縁抵抗が得ら
れた。As is clear from FIG. 2, the relationship between the insulation resistance of the sheathed heater and the amount of silica sol added was in good agreement with the relationship between the specific resistance of fused magnesia and the amount of silica sol added shown in FIG. For fused magnesia A, the maximum insulation resistance can be obtained by adding around 2 wt% of silica sol in terms of silica, and for fused magnesia B, the same
The maximum insulation resistance was obtained by adding approximately wt% of silica sol.
このように本発明のシーズヒータは、従来の電融マグネ
シアのみを電気絶縁粉末として用いたシーズヒータと比
べて、通電時の絶縁抵抗を向上させることができると共
に、比較的低純度の電融マグネシアを用いて高い絶縁抵
抗のシーズヒータを提供できることがわかった。また絶
縁抵抗の向上により、シーズヒータの高温化が図れると
共に、全長を短かくしたり、外径を細くしたりするとい
う具合に、シーズヒータのコンパクト化も図れるように
なった。As described above, the sheathed heater of the present invention can improve the insulation resistance during energization compared to conventional sheathed heaters that use only fused magnesia as an electrical insulating powder, and can also improve the insulation resistance when electricity is applied. It was found that a sheathed heater with high insulation resistance could be provided using this method. Furthermore, improved insulation resistance has made it possible to raise the temperature of the sheathed heater, and it has also become possible to make the sheathed heater more compact by shortening its overall length and reducing its outer diameter.
発明の効果
上記実施例の説明から明らかなように本発明によれば、
電気絶縁粉末として、電融マグネシアを使用し、シリカ
ゾルをシリカ重量に換算して０．３〜１５ｗｔ％添加し
、４５０℃以上の温度で加熱処理しているため、特に通
電時の電気絶縁特性に優れ、信頼性が高く、しかも安価
なシーズヒータを提供することができるものである。Effects of the Invention As is clear from the description of the above embodiments, according to the present invention,
As the electrical insulating powder, fused magnesia is used, 0.3 to 15 wt% of silica sol is added in terms of silica weight, and heat treatment is performed at a temperature of 450°C or higher, which improves electrical insulation properties especially when electricity is applied. It is possible to provide an excellent, highly reliable, and inexpensive sheathed heater.
第１図は本発明の一実施例におけるシーズヒータの電融
マグネシアの固有抵抗とシリカゾルの添加量の関係を示
すグラフ、第２図は同シーズヒータの絶縁抵抗とシリカ
ゾルの添加量の関係を示すグラフである。
代理人の氏名 弁理士 中 尾 敏 男 ほか１名第１
図
シリカにＰＡ！シたシワ力
ジルの添７０量 ｗｔ％Figure 1 is a graph showing the relationship between the specific resistance of fused magnesia and the amount of silica sol added in the sheathed heater in an embodiment of the present invention, and Figure 2 is a graph showing the relationship between the insulation resistance of the same sheathed heater and the amount of silica sol added. It is a graph. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure PA on silica! 70 amount wt%
Claims (1)
リカゾルをシリカ重量に換算して０．３〜１５ｗｔ％添
加し、４５０℃以上の温度で加熱処理したことを特徴と
するシーズヒータ。A sheathed heater characterized in that fused magnesia powder is used as an electrical insulating powder, 0.3 to 15 wt% of silica sol is added in terms of silica weight, and the mixture is heat-treated at a temperature of 450°C or higher.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32584687A JPH01166481A (en) | 1987-12-23 | 1987-12-23 | Sheathed heater |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32584687A JPH01166481A (en) | 1987-12-23 | 1987-12-23 | Sheathed heater |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01166481A true JPH01166481A (en) | 1989-06-30 |
Family
ID=18181271
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32584687A Pending JPH01166481A (en) | 1987-12-23 | 1987-12-23 | Sheathed heater |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01166481A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0260934A (en) * | 1988-06-28 | 1990-03-01 | Amoco Corp | Polyimide and copolyimide which have low dielectric constant and low moisture absorptivity and are used for both interlayer insulator and base plate coating film |
| JPH0436979A (en) * | 1990-05-31 | 1992-02-06 | Matsushita Electric Ind Co Ltd | Sheathed heater |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5424332A (en) * | 1977-07-26 | 1979-02-23 | Hitachi Heating Appliance Co Ltd | Sheathed heater |
-
1987
- 1987-12-23 JP JP32584687A patent/JPH01166481A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5424332A (en) * | 1977-07-26 | 1979-02-23 | Hitachi Heating Appliance Co Ltd | Sheathed heater |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0260934A (en) * | 1988-06-28 | 1990-03-01 | Amoco Corp | Polyimide and copolyimide which have low dielectric constant and low moisture absorptivity and are used for both interlayer insulator and base plate coating film |
| JPH0436979A (en) * | 1990-05-31 | 1992-02-06 | Matsushita Electric Ind Co Ltd | Sheathed heater |
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