JPH0311081B2 - - Google Patents
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- Publication number
- JPH0311081B2 JPH0311081B2 JP59281418A JP28141884A JPH0311081B2 JP H0311081 B2 JPH0311081 B2 JP H0311081B2 JP 59281418 A JP59281418 A JP 59281418A JP 28141884 A JP28141884 A JP 28141884A JP H0311081 B2 JPH0311081 B2 JP H0311081B2
- Authority
- JP
- Japan
- Prior art keywords
- positive characteristic
- parts
- weight
- characteristic semiconductor
- porcelain
- 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.)
- Expired - Lifetime
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- 239000004065 semiconductor Substances 0.000 claims description 60
- 229910052573 porcelain Inorganic materials 0.000 claims description 40
- 230000004907 flux Effects 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 18
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 claims description 17
- 229910002113 barium titanate Inorganic materials 0.000 claims description 17
- 230000009467 reduction Effects 0.000 claims description 15
- 229910010413 TiO 2 Inorganic materials 0.000 claims description 10
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 7
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 7
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 5
- 230000007704 transition Effects 0.000 claims description 5
- 229910052727 yttrium Inorganic materials 0.000 claims description 5
- 229910052772 Samarium Inorganic materials 0.000 claims description 4
- 229910052746 lanthanum Inorganic materials 0.000 claims description 4
- 229910052758 niobium Inorganic materials 0.000 claims description 4
- 229910052715 tantalum Inorganic materials 0.000 claims description 4
- 229910052684 Cerium Inorganic materials 0.000 claims description 3
- 238000012360 testing method Methods 0.000 description 15
- 230000006866 deterioration Effects 0.000 description 13
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 12
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 12
- 239000002019 doping agent Substances 0.000 description 11
- 239000007789 gas Substances 0.000 description 8
- 230000008859 change Effects 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 239000001294 propane Substances 0.000 description 6
- 239000000919 ceramic Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 238000010304 firing Methods 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 230000005389 magnetism Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000000465 moulding Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- 229910002651 NO3 Chemical class 0.000 description 1
- 229910005544 NiAg Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical class [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000007772 electroless plating Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Landscapes
- Compositions Of Oxide Ceramics (AREA)
- Thermistors And Varistors (AREA)
Description
［産業上の利用分野］
本発明は、キユリー温度を越えると電気抵抗値
が著しく増大するPTC特性を有する正特性半導
体磁器に関するものであり、主として還元性ガス
雰囲気下で使用される自己温度制御型ヒータ、温
度センサ等に利用される耐還元性を有する正特性
半導体磁器に関するものである。
［従来の技術］
従来チタン酸バリウムにＹ、La、Sm、Ce、
Ga等の希土類元素あるいはNb、Ta等の遷移元
素からなるドーパントを添加し、大気中、1200〜
1400℃で焼成した磁器において、キユリー点で電
気抵抗値が急に増加する、いわゆる正特性
（PTC特性）を示すことが知られている。そして
この特性を利用し、ヒータ、温度センサ等に使用
されている。
［発明が解決しようとする課題］
従来、チタン酸バリウム半導体を主成分とする
正特性半導体磁器を使用した半導体素子は、水素
ガス、或いはガソリン等の還元性雰囲気中で使用
された場合には、その特徴であるPTC特性が劣
化するという問題点があつた。例えば自己温度制
御型ヒーターとして使用した場合には、PTC特
性の劣化（以下Ｒ−Ｔ劣化と言う）により、制御
されるべき温度になつても抵抗値が上がらず、最
悪の場合には、通電によりPTC素子が溶損する
という問題があつた。また、Ｒ−Ｔ劣化は還元性
雰囲気中だけで生じるものではなく、窒素又はア
ルゴンガス等の中性雰囲気中においても、程度の
差はあれ、Ｒ−Ｔ劣化が生じることもわかつてい
る。
以上のことからチタン酸バリウム半導体を主成
分とする正特性半導体磁器を使用した半導体素子
の使用環境は限定されざるを得なかつた。また上
記還元性雰囲気の環境にて使用される場合には、
樹脂或いは金属等のケースに素子を封入し、環境
から遮蔽して使用せざるを得なかつた。その為に
放熱性の悪化に伴う性能の低下、部品点数及び組
付工数の増加に伴うコスト高、等の問題点が生じ
ていた。
本発明者は上記の問題点及び従来の知見に鑑
み、鋭意研究した結果、ドーパントを含むチタン
酸バリウム系組成物に対して、TiO2、Al2O3及び
SiO2から構成されるフラツクスが、還元性雰囲
気中でＲ−Ｔ劣化を防ぐことを発見し、本発明を
完成したものである。
［課題を解決するための手段］
本発明の耐還元性を有する正特性半導体磁器は
() 一般式Ba1-xM3 xTiO3あるいはBaTi1-yM5 y
O3（ただしM3はＹ、La、Sm、Ce、Ga等の希
土類元素、M5はNb、Ta等の遷移元素、ｘは
0.001〜0.05、ｙは0.0005〜0.005をそれぞれ示
す）よりなるチタン酸バリウム系組成物100重
量部と、
() TiO2が0.14〜2.88重量部と、Al2O3が0.1〜
1.6重量部およびSiO2が0.1〜1.6重量部とにより
構成されるフラツクス成分とからなることを特
徴とする。
本発明の耐還元性を有する正特性半導体磁器に
使用されるチタン酸バリウム系組成物は、一般式
(1)あるは(2)に示されるチタン酸バリウム系組成物
である。
Ba1-xM3 xTiO3 ……(1)
BaTi1-yM5 yO3 ……(2)
ここでM3及びM5は通常使用される希土類元素
及び遷移元素から選ばれるドーパントであり、
M3としてはＹ、La、Sm、Ce、Ga等の希土類元
素の何れでもよく、M5としては、Nb、Ta等の
遷移元素の何れでもよい。またｘ及びｙの値はそ
れぞれ0.001〜0.005、0.0005〜0.005の範囲が望ま
しい。
本発明の最大の特徴であるフラツクス成分は、
チタン酸バリウム半導体を主成分とする正特性半
導体磁気中に、チタン酸バリウム系組成物100重
量部に対しTiO2が0.14〜2.88重量％、Al2O3が0.1
〜1.6重量部及びSiO2が0.1〜1.6重量部含まれてい
る。フラツクス成分は各成分とも範囲内で添加さ
れることが必要であり、添加量が範囲より少なく
なつても、また、多過ぎても、還元性雰囲気中で
のＲ−Ｔ劣化を防ぐことは困難となる。さらにフ
ラツクス成分の添加量の増大に伴い、正特製半導
体磁気の比抵抗が大きくなる傾向がある。この不
具合を解決するにはフラツクス成分は、チタン酸
バリウム系組成物100重量部に対しTiO2が0.14〜
1.15重量部、Al2O3が0.2〜0.6重量部及びSiO2が
0.2〜0.8重量部含まれていることが望ましい。各
成分がこの含有量の範囲にあれば得られる正特製
半導体磁器の比抵抗は100Ω・cm以下となり自動
車部品への応用に適している。
上記フラツクス成分はチタン酸バリウム系組成
物と共に混合され、焼成される。上記フラツクス
成分は、上記３成分を上記範囲内で添加する事に
よつてはじめて良好な耐還元性を有する正特性半
導体磁気を得ることができるものである。また、
上記範囲内で上記各成分の比率、又はフラツクス
全体としての添加物を変化されることにより、正
特性半導体磁器の結晶粒子の成長度合等の調整が
可能となり、種々の性能を有する正特性半導体磁
器を得ることが可能となる。しかしながら、上記
３成分のうちいづれか１成分、もしくは２成分が
欠落した場合は半導体化しても希望の耐還元性を
得ることは困難であり、焼成条件または不純物の
影響を受けやすくなつて安定したPTC特性を得
ることも困難となる。
本発明の正特性半導体磁器には上記の成分以外
に、キユリー点制御剤としてPb、Sr、Zr、Sn等
の元素を添加することも好ましく、PTC特性を
向上させる添加剤としてMn、Fe、Co等の元素を
微量添加することも好ましい。
本発明の正特性半導体磁器は従来と同様の方法
で混合、成形及び焼成して得られる。その半導体
化の過程は次の通りである。
まず800〜1100℃の温度にてチタン酸バリウム
が生成するが、その状態ではまだ結晶格子が乱れ
ている。1200℃〜1280℃になるたフラツクス成分
の一部が溶融し始め、チタン酸バリウムは急激に
成長しながらドーパントとともに半導体化する。
そしてフラツクス成分が完全に溶融しチタン酸バ
リウム粒子はフラツクス成分の液相内にて半導体
化する。このようにして焼成された後冷却行程に
入ると、フラツクス成分の液相はチタン酸バリウ
ム半導体粒子を被覆しながら固化し、一体化す
る。
本発明の正特性半導体磁器が耐還元性を有する
機構については明確ではないが、フラツクス成分
がチタン酸バリウム半導体粒界を被覆し、還元性
雰囲気から保護している為であると推察される。
また、従来の正特性半導体磁器では吸水率が0.2
％以上であつたのに対し、本発明の正特性半導体
磁器はほとんど０％に近く、吸水率が著しく低下
している。この理由によつて還元性物質の侵入が
少なくなつていることも耐還元性を有する一因と
考えられる。
［発明の効果］
本発明の正特性半導体磁器は還元性雰囲気中で
使用されてもＲ−Ｔ劣化がほとんど生じず、優れ
たPTC特性を有している。この理由により水素
ガス又はガソリン等の還元性雰囲気においても、
樹脂や金属で密封する必要はなく、露出構造にて
使用することが可能であり、製品設計の自由度が
拡大する他、性能向上、コストの低減等に対し特
に効果がある。または、本発明の正特性半導体磁
器は、不純物、焼成条件、及びドーパントの添加
量等の影響を受けにくい為、安価な工業用原料が
使用できるなど、従来に比べ製造がはるかに容易
となる。
さらに本発明の正特性半導体磁器では、ドーパ
ントの添加により、半導体磁器の抵抗値を低下さ
せることができ、かつ抵抗値を安定に維持させる
ことができる。
［実施例］
以下試験例により本発明の正特性半導体磁器の
性能を説明する。
試験例 １
BaCO3とTiO2の等モル混合物にＹ、La、Nb
などのドーパントの酸化物が混合されたチタン酸
バリウム系組成物、TiO2、Al2O3及びSiO2を原
料とした。なおこれらは全て工業用原料を用い
た。これらの原料をそれぞれ第１表〜第３表に示
した84種類の組成に配合し、それぞれメノウ石と
共にボールミルにて湿式で20時間粉砕混合を行な
つた。そして、これらの混合物を乾燥した後900
〜1200℃の温度で仮焼した。こうして得られた仮
焼物にMn等の添加物を調合し、メノウ玉石とボ
ールミルにて湿式で20時間粉砕混合を行なつた。
乾燥後それぞれの混合粉末に結合剤として10％の
ポリビニルアルコール水溶液を１重量％添加混合
し、800Kg／cm2の圧力でプレス成形した。これら
の成形物を空気中で1200℃〜1400℃にて２時間焼
成し、直径20mm、厚さ３mmの円板状正特性半導体
磁器を製造した。
得られた84種類の正特性半導体磁器の特性を調
べるため、各正特性半導体磁器の両面にNiAg電
極（Ni無電解メツキ、Agペースト）を付与し、
大気中25℃における電気抵抗値（比抵抗Ro）を
測定し、結果を第１表、第２表、第３表に示す。
また水素ガス雰囲気中に各正特性半導体磁器を投
入し、250℃にて、各正特性半導体磁器の投入直
後の電気抵抗値（R1）及び30分後の電気抵抗値
（R2）を測定し、次式(3)より抵抗変化率（△Ｒ）
を測定した。
△Ｒ＝100×（R1−R2）／R1 ……(3)
ここでR2がR1に近い程、すなわち△Ｒが０に近
い程、耐還元性に優れている。
各正特性半導体磁器の評価は△Ｒが０〜−10％
を（○）、−10〜−50％（△）、一50％〜を（×）
として第１表、第２表及び第３表に示す。
第１表〜第２表において、本発明の正特性半導
体磁器、すなわちBaCO3とTiO2の等モル混合物
にＹが0.25モル％含有された主剤成分100重量部
に対し、フラツクス成分としてTiO2が0.14〜2.88
重量部、Al2O3が0.1〜1.6重量部及びSiO2が0.1〜
1.6重量部含まれる正特性半導体磁器（No.16〜No.
38、No.37〜No.84）は、フラツクス成分が不足する
正特性半導体磁器（No.１〜No.10）に比べて△Ｒの
絶対値が小さく、明らかに耐還元性に優れてい
る。また、特に望ましい範囲であるTiO2が0.14
〜1.15重量％、Al2O3が0.2〜0.6重量部及びSiO2
が0.2〜0.8重量部含まれる正特性半導体磁器は、
比抵抗が100Ω・cm以下であり、かつ△Ｒの絶対
値も14以下と小さく耐還元性に優れているので、
自動車用部品への応用に最適である。
またNo.39〜No.60に示されるように、種々のドー
パントを含む場合について本発明が適用できるこ
とが明らかである。そして例えば比抵抗の値をみ
ると、ドーパントの含有量にも最適値があること
が明らかである。
さらにNo.11〜No.15から明らかなように、フラツ
クス成分が本発明の範囲に無い場合には、ドーパ
ントの種類を問わず耐還元性に劣つている。
試験例 ２
次に試験例１を用いたものと同一の組成の原料
を使用し、試験例１と同様に混合、成形、焼成を
行なつて、直径20mm、厚さ３mmの円板状特性半導
体磁器を製造した。得られた正特性半導体磁器は
試験例１と同様に表面にNi−Ag電極が付
[Industrial Application Field] The present invention relates to a positive characteristic semiconductor porcelain having a PTC characteristic in which the electrical resistance value increases significantly when the Curie temperature is exceeded, and is a self-temperature control type porcelain mainly used in a reducing gas atmosphere. The present invention relates to positive characteristic semiconductor porcelain that has reduction resistance and is used in heaters, temperature sensors, etc. [Conventional technology] Conventionally, barium titanate was coated with Y, La, Sm, Ce,
By adding dopants consisting of rare earth elements such as Ga or transition elements such as Nb and Ta,
It is known that porcelain fired at 1400°C exhibits a so-called positive characteristic (PTC characteristic) in which the electrical resistance suddenly increases at the Curie point. Taking advantage of this characteristic, it is used in heaters, temperature sensors, etc. [Problems to be Solved by the Invention] Conventionally, semiconductor elements using positive characteristic semiconductor porcelain mainly composed of barium titanate semiconductors have problems when used in a reducing atmosphere such as hydrogen gas or gasoline. There was a problem in that its characteristic PTC characteristics deteriorated. For example, when used as a self-temperature-controlled heater, due to deterioration of PTC characteristics (hereinafter referred to as R-T deterioration), the resistance value does not increase even when the temperature that should be controlled is reached, and in the worst case, the current cannot be turned on. There was a problem that the PTC element was damaged by melting. Further, it is known that RT deterioration does not only occur in a reducing atmosphere, but also in a neutral atmosphere such as nitrogen or argon gas, although there are differences in degree. For these reasons, the usage environment of semiconductor devices using positive characteristic semiconductor ceramics whose main component is barium titanate semiconductor has been limited. In addition, when used in the above-mentioned reducing atmosphere environment,
The device had to be enclosed in a case made of resin or metal, and used while shielded from the environment. This has led to problems such as a decrease in performance due to poor heat dissipation, and high costs due to an increase in the number of parts and assembly man-hours. In view of the above problems and conventional knowledge, the present inventor conducted extensive research and found that TiO 2 , Al 2 O 3 and
The present invention was completed by discovering that a flux composed of SiO 2 prevents RT deterioration in a reducing atmosphere. [Means for Solving the Problems] The positive characteristic semiconductor porcelain having reduction resistance of the present invention has the following general formula: Ba 1-x M 3 x TiO 3 or BaTi 1-y M 5 y
O 3 (However, M 3 is a rare earth element such as Y, La, Sm, Ce, Ga, etc., M 5 is a transition element such as Nb, Ta, etc., x is
100 parts by weight of a barium titanate composition consisting of (0.001 to 0.05, y represents 0.0005 to 0.005, respectively), () 0.14 to 2.88 parts by weight of TiO2 , and 0.1 to 0.1 to
1.6 parts by weight and a flux component consisting of 0.1 to 1.6 parts by weight of SiO 2 . The barium titanate-based composition used in the reduction-resistant positive characteristic semiconductor porcelain of the present invention has the general formula
(1) or (2) is a barium titanate-based composition. Ba 1-x M 3 x TiO 3 ...(1) BaTi 1-y M 5 y O 3 ...(2) Here, M 3 and M 5 are dopants selected from commonly used rare earth elements and transition elements. can be,
M3 may be any rare earth element such as Y, La, Sm, Ce, or Ga, and M5 may be any transition element such as Nb or Ta. Further, the values of x and y are preferably in the ranges of 0.001 to 0.005 and 0.0005 to 0.005, respectively. The flux component, which is the greatest feature of the present invention, is
In a positive characteristic semiconductor magnet whose main component is a barium titanate semiconductor, TiO 2 is 0.14 to 2.88 weight % and Al 2 O 3 is 0.1 weight % based on 100 parts by weight of the barium titanate based composition.
~1.6 parts by weight and 0.1-1.6 parts by weight of SiO2 . It is necessary to add each flux component within the range, and even if the amount added is less than the range or too much, it is difficult to prevent RT deterioration in a reducing atmosphere. becomes. Furthermore, as the amount of the flux component added increases, the specific resistance of the Seitotsu Semiconductor Magnetism tends to increase. To solve this problem, the flux component should contain 0.14 to 0.14 parts of TiO 2 per 100 parts by weight of the barium titanate composition.
1.15 parts by weight, 0.2-0.6 parts by weight of Al 2 O 3 and SiO 2
It is desirable that the content is 0.2 to 0.8 parts by weight. If the content of each component is within this range, the resistivity of the resulting semiconducting porcelain will be 100Ω·cm or less, making it suitable for application to automobile parts. The above flux component is mixed with a barium titanate composition and fired. A positive characteristic semiconductor magnetism having good reduction resistance can only be obtained by adding the above flux components within the above ranges. Also,
By changing the ratio of each of the above components or the additives in the flux as a whole within the above range, it is possible to adjust the growth degree of crystal grains of positive characteristic semiconductor porcelain, and it is possible to produce positive characteristic semiconductor porcelain with various performances. It becomes possible to obtain. However, if one or two of the above three components are missing, it is difficult to obtain the desired reduction resistance even if it is made into a semiconductor, and the PTC becomes more susceptible to firing conditions or impurities, resulting in stable PTC. It is also difficult to obtain characteristics. In addition to the above-mentioned components, it is also preferable to add elements such as Pb, Sr, Zr, Sn, etc. as a Curie point controlling agent to the positive characteristic semiconductor porcelain of the present invention, and Mn, Fe, Co, etc. as additives to improve PTC characteristics. It is also preferable to add trace amounts of elements such as. The positive characteristic semiconductor porcelain of the present invention can be obtained by mixing, molding and firing in the same manner as in the prior art. The process of converting it into a semiconductor is as follows. First, barium titanate is formed at a temperature of 800 to 1100°C, but in that state the crystal lattice is still disordered. When the temperature reaches 1200°C to 1280°C, part of the flux component begins to melt, and barium titanate rapidly grows and turns into a semiconductor along with the dopant.
Then, the flux component is completely melted and the barium titanate particles are converted into a semiconductor in the liquid phase of the flux component. After being fired in this manner, when a cooling process is started, the liquid phase of the flux component solidifies and integrates the barium titanate semiconductor particles while covering them. Although the mechanism by which the positive characteristic semiconductor porcelain of the present invention has reduction resistance is not clear, it is presumed that the flux component coats the barium titanate semiconductor grain boundaries and protects them from a reducing atmosphere.
In addition, conventional positive characteristic semiconductor porcelain has a water absorption rate of 0.2
% or more, whereas the positive characteristic semiconductor porcelain of the present invention has a water absorption rate of almost 0%, which is a marked decrease in water absorption rate. For this reason, the intrusion of reducing substances is reduced, which is considered to be one of the reasons for the reduction resistance. [Effects of the Invention] The positive characteristic semiconductor ceramic of the present invention exhibits almost no RT deterioration even when used in a reducing atmosphere, and has excellent PTC characteristics. For this reason, even in reducing atmospheres such as hydrogen gas or gasoline,
There is no need to seal it with resin or metal, and it can be used in an exposed structure, which expands the degree of freedom in product design and is particularly effective in improving performance and reducing costs. Alternatively, the positive characteristic semiconductor porcelain of the present invention is less affected by impurities, firing conditions, the amount of dopants added, etc., and thus can be manufactured using inexpensive industrial raw materials, making it much easier to manufacture than in the past. Further, in the positive characteristic semiconductor ceramic of the present invention, by adding a dopant, the resistance value of the semiconductor ceramic can be lowered and the resistance value can be stably maintained. [Example] The performance of the positive characteristic semiconductor porcelain of the present invention will be explained below using test examples. Test example 1 Y, La, Nb in an equimolar mixture of BaCO 3 and TiO 2
The raw materials were a barium titanate-based composition mixed with dopant oxides such as TiO 2 , Al 2 O 3 and SiO 2 . Note that all of these used industrial raw materials. These raw materials were blended into 84 different compositions shown in Tables 1 to 3, and pulverized and mixed together with agate in a wet ball mill for 20 hours. And after drying these mixtures 900
Calcined at a temperature of ~1200℃. Additives such as Mn were added to the calcined product thus obtained, and the mixture was wet-pulverized and mixed with agate boulders in a ball mill for 20 hours.
After drying, 1% by weight of a 10% polyvinyl alcohol aqueous solution was added as a binder to each of the mixed powders, and the mixture was press-molded at a pressure of 800 kg/cm 2 . These molded products were fired in air at 1200° C. to 1400° C. for 2 hours to produce a disk-shaped positive temperature semiconductor porcelain having a diameter of 20 mm and a thickness of 3 mm. In order to investigate the characteristics of the 84 types of positive characteristic semiconductor porcelain obtained, NiAg electrodes (Ni electroless plating, Ag paste) were applied to both sides of each positive characteristic semiconductor porcelain.
The electrical resistance value (specific resistance Ro) at 25° C. in the atmosphere was measured, and the results are shown in Tables 1, 2, and 3.
In addition, each positive characteristic semiconductor porcelain was placed in a hydrogen gas atmosphere, and at 250℃, the electrical resistance value (R 1 ) of each positive characteristic semiconductor porcelain was measured immediately after the addition (R 1 ) and after 30 minutes (R 2 ). Then, from the following formula (3), the resistance change rate (△R)
was measured. ΔR=100×(R 1 −R 2 )/R 1 (3) Here, the closer R 2 is to R 1 , that is, the closer ΔR is to 0, the better the reduction resistance is. The evaluation of each positive characteristic semiconductor porcelain is △R from 0 to -10%.
(○), -10 to -50% (△), -50% to (×)
as shown in Tables 1, 2 and 3. In Tables 1 and 2, TiO 2 was added as a flux component to 100 parts by weight of the positive characteristic semiconductor porcelain of the present invention, that is, an equimolar mixture of BaCO 3 and TiO 2 containing 0.25 mol% of Y. 0.14~2.88
Parts by weight, 0.1 to 1.6 parts by weight of Al 2 O 3 and 0.1 to 1.6 parts by weight of SiO 2
Contains 1.6 parts by weight of positive characteristic semiconductor porcelain (No. 16 to No.
38, No. 37 to No. 84) have a smaller absolute value of △R than the positive characteristic semiconductor porcelains (No. 1 to No. 10), which lack flux components, and clearly have superior reduction resistance. . Also, TiO 2 is in a particularly desirable range of 0.14
~1.15 wt%, 0.2-0.6 wt% Al2O3 and SiO2
Positive characteristic semiconductor porcelain containing 0.2 to 0.8 parts by weight of
It has a specific resistance of less than 100Ω・cm, and the absolute value of △R is less than 14, so it has excellent reduction resistance.
Ideal for application to automotive parts. Furthermore, as shown in Nos. 39 to 60, it is clear that the present invention is applicable to cases containing various dopants. For example, when looking at the value of specific resistance, it is clear that there is an optimum value for the content of the dopant. Furthermore, as is clear from No. 11 to No. 15, if the flux component is not within the range of the present invention, the reduction resistance is poor regardless of the type of dopant. Test Example 2 Next, raw materials with the same composition as those used in Test Example 1 were mixed, molded, and fired in the same manner as in Test Example 1 to produce a disk-shaped characteristic semiconductor with a diameter of 20 mm and a thickness of 3 mm. Made porcelain. The obtained positive characteristic semiconductor porcelain had a Ni-Ag electrode on its surface as in Test Example 1.
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】
与され、大気中において、各正特性半導体磁器の
電気抵抗値を室温から300℃までの間ほぼ連続的
に測定して、第２図の概念図に示す実線イの
PTC特性を表わず曲線を求めた。次に各正特性
半導体磁器をサワーガソリン中に浸漬し、15〜
40Vの電圧を100時間付与する浸漬通電耐久試験
を行なつた。ここでサワーガソリンとは、酸化が
進んで過酸化物や酸が生成したガソリンのことで
あり、促進試験用として使用されるものである。
浸漬通電耐久試験後の正特性半導体磁器は大気中
において、電気抵抗値を室温から300℃までの間
ほぼ連続的に測定され、第２図の破線ロのPTC
特性を表わす曲線を得た。得られた２つの曲線の
差から第２図に示すＲ−Ｔ劣化Ａを求め、結果を
第１表〜第３表に示す。なお、Ｒ−Ｔ劣化Ａは次
式により求められる。
log（R′max／R′min）
−log（Rmax／Rmin）＝Ｒ−Ｔ劣化(A)
（Ｒ……耐久試験前の抵抗値、R′……耐久試験
後の抵抗値、max……最大値、min……最小値）
第１表〜第３表において、測定結果の記載が無
い箇所があるが、これは比抵抗が100Ω・cm以上
の正特性半導体磁器については、浸漬通電耐久試
験で十分な発熱が得られず、信頼性のあるデータ
とならない為測定しなかつたものである。また、
結果の判定は(A)の度合が１以内を（○）、１〜２
を（△）、２以上を（×）とした。
本発明の正特性半導体磁器（No.16〜No.84）は、
これ以上の正特性半導体磁器（No.１〜No.15）に比
べ、Ｒ−Ｔ劣化は対数値で−2.8〜＋0.4と小さく
明らかに耐還元正に優れている。また特に望まし
い範囲であるTiO2が0.14〜1.15重量部、Al2O3が
0.2〜0.6重量部及びSiO2が0.2〜0.8重量部含まれ
る正特性半導体磁器は、Ｒ−Ｔ劣化が１以下であ
り、耐還元性に特に優れていることがわかる。
試験例 ３
試験例１に使用した正特性半導体磁器のうち従
来の組成としてNo.５を、本発明の組成としてNo.38
を遷び、試験例１と同様に混合、成形、焼成を行
なつて、直径20mm、厚さ３mmの円板状正特性半導
体磁器を製造した。得られた２種類の正特性半導
体磁器の両面にNi−Ag電極を付与し、還元性雰
囲気である水素ガス及びプロパンガスにおいて、
250℃で30分間放置した。その30分の間の各正特
性半導体磁器の電気抵抗値をほぼ連続的に測定
し、還元性雰囲気へ投入した直後の、電気抵抗値
を基準として抵抗変化率を求め、結果を第１図に
示す。第１図より明らかに、従来の組成の正特性
半導体磁器No.５は水素ガス中１及びプロパンガス
中２において70〜80％の抵抗変化率を示している
が、本発明の正特性半導体磁器No.38は水素ガス及
びプロパンガスのどちらの雰囲気中でも抵抗変化
率はほとんど０％であつた。すなわち、本発明の
正特性半導体磁器は水素ガス及びプロパンガスの
還元性雰囲気中でも電気抵抗値がほとんど変化せ
ず、耐還元性に優れている。
なお、本実施例ではドーパント元素を酸化物と
して添加したが、本発明はこれに限られるもので
はなく、塩化物あるいは硝酸塩などの形態で添加
しても同様の正特性半導体磁器が得られる。[Table] The electrical resistance values of each positive characteristic semiconductor porcelain were measured almost continuously from room temperature to 300℃ in the atmosphere, and the solid line A shown in the conceptual diagram of Figure 2 was obtained.
A curve was obtained without representing the PTC characteristics. Next, each positive characteristic semiconductor porcelain was immersed in sour gasoline, and
An immersion current durability test was conducted in which a voltage of 40V was applied for 100 hours. Here, sour gasoline refers to gasoline that has been oxidized to produce peroxides and acids, and is used for accelerated testing.
After the immersion current durability test, the electrical resistance of the positive characteristic semiconductor porcelain was measured almost continuously in the atmosphere from room temperature to 300℃, and the PTC value shown by the broken line B in Figure 2 was measured almost continuously from room temperature to 300℃.
A curve representing the characteristics was obtained. The RT deterioration A shown in FIG. 2 was calculated from the difference between the two obtained curves, and the results are shown in Tables 1 to 3. In addition, RT deterioration A is calculated|required by the following formula. log (R'max/R'min) -log (Rmax/Rmin)=RT deterioration (A) (R...Resistance value before durability test, R'...Resistance value after durability test, max... (maximum value, min...minimum value) In Tables 1 to 3, there are some places where measurement results are not listed, but this is due to the immersion current durability test for positive characteristic semiconductor porcelain with a resistivity of 100Ω・cm or more. This was not measured because sufficient heat generation could not be obtained and the data would not be reliable. Also,
Judgment of the results is as follows: degree of (A) is within 1 (○), 1-2
(△), and 2 or more (x). The positive characteristic semiconductor porcelains (No. 16 to No. 84) of the present invention are:
Compared to the positive characteristic semiconductor porcelains (No. 1 to No. 15), which have higher positive characteristics, the RT deterioration is -2.8 to +0.4 in logarithm, which is small and clearly superior in reduction resistance. In addition, TiO 2 is in a particularly desirable range of 0.14 to 1.15 parts by weight, and Al 2 O 3 is in a particularly desirable range.
It can be seen that the positive characteristic semiconductor porcelain containing 0.2 to 0.6 parts by weight and 0.2 to 0.8 parts by weight of SiO 2 has RT deterioration of 1 or less and is particularly excellent in reduction resistance. Test Example 3 Among the positive characteristic semiconductor porcelains used in Test Example 1, No. 5 was used as the conventional composition, and No. 38 was used as the composition of the present invention.
Mixing, molding, and firing were carried out in the same manner as in Test Example 1 to produce a disk-shaped positive characteristic semiconductor porcelain having a diameter of 20 mm and a thickness of 3 mm. Ni-Ag electrodes were applied to both sides of the two types of positive characteristic semiconductor porcelain obtained, and in a reducing atmosphere of hydrogen gas and propane gas,
It was left at 250°C for 30 minutes. The electrical resistance value of each positive characteristic semiconductor porcelain was measured almost continuously during that 30 minutes, and the rate of change in resistance was determined based on the electrical resistance value immediately after being placed in the reducing atmosphere. The results are shown in Figure 1. show. It is clear from FIG. 1 that positive characteristic semiconductor porcelain No. 5 with the conventional composition shows a resistance change rate of 70 to 80% in hydrogen gas (1) and propane gas (2), but the positive characteristic semiconductor porcelain of the present invention In No. 38, the resistance change rate was almost 0% in both hydrogen gas and propane gas atmospheres. That is, the positive characteristic semiconductor porcelain of the present invention has excellent resistance to reduction, with almost no change in electrical resistance even in a reducing atmosphere of hydrogen gas and propane gas. Although the dopant element was added in the form of an oxide in this example, the present invention is not limited to this, and a similar positive characteristic semiconductor ceramic can be obtained even if the dopant element is added in the form of a chloride or nitrate.
第１図は水素ガス及びプロパンガス中での電気
抵抗値の変化を表わす線図、第２図はガソリン中
でのＲ−Ｔ劣化を示す線図である。
１……水素ガス中での変化、２……プロパンガ
ス中での変化、Ａ……Ｒ−Ｔ劣化。
FIG. 1 is a diagram showing changes in electrical resistance in hydrogen gas and propane gas, and FIG. 2 is a diagram showing RT deterioration in gasoline. 1...Change in hydrogen gas, 2...Change in propane gas, A...RT deterioration.
Claims (1)
M5 yO3（ただしM3は、Ｙ、La、Sm、Ce、Ga
等の希土類元素、M5はNb、Ta等の遷移元素、
ｘは0.001〜0.05、ｙは0.0005〜0.005をそれぞ
れ示す）よりなるチタン酸バリウム系組成物
100重量部と、 () TiO2が0.14〜2.88重量部と、Al2O3が0.1〜
1.6重量部およびSiO2が0.1〜1.6重量部とにより
構成されるフラツクス成分とからなることを特
徴とする耐還元性を有する正特性半導体磁器。[Claims] 1 () General formula Ba 1-x M 3 x TiO 3 or BaTi 1-y
M 5 y O 3 (M 3 is Y, La, Sm, Ce, Ga
Rare earth elements such as M5 , transition elements such as Nb and Ta,
barium titanate-based composition consisting of
100 parts by weight, () 0.14 to 2.88 parts by weight of TiO 2 and 0.1 to 2.88 parts by weight of Al 2 O 3
1.6 parts by weight of a flux component and 0.1 to 1.6 parts by weight of SiO 2 . A positive characteristic semiconductor porcelain having reduction resistance.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59281418A JPS61154003A (en) | 1984-12-26 | 1984-12-26 | Reduction resisting positive temperature coefficient semiconductor porcelain |
| DE8585116071T DE3579427D1 (en) | 1984-12-26 | 1985-12-17 | REDUCTION RESISTANT SEMICONDUCTOR PORCELAIN WITH POSITIVE TEMPERATURE COEFFICIENT OF THE RESISTANCE. |
| AU51364/85A AU572013B2 (en) | 1984-12-26 | 1985-12-17 | Anti-reducing semi conducting porcelain with a positive temperature coefficient of resistance |
| EP85116071A EP0186095B1 (en) | 1984-12-26 | 1985-12-17 | Anti-reducing semiconducting porcelain having a positive temperature coefficient of resistance |
| CA000498513A CA1272589A (en) | 1984-12-26 | 1985-12-23 | Anti-reducing semiconducting porcelain having a positive temperature coefficient of resistance |
| US07/096,242 US4834052A (en) | 1984-12-26 | 1987-09-08 | Internal combustion engine having air/fuel mixture with anti-reducing semiconducting porcelain having a positive temperature coefficient of resistance and method for using such porcelain for heating air/fuel mixture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59281418A JPS61154003A (en) | 1984-12-26 | 1984-12-26 | Reduction resisting positive temperature coefficient semiconductor porcelain |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61154003A JPS61154003A (en) | 1986-07-12 |
| JPH0311081B2 true JPH0311081B2 (en) | 1991-02-15 |
Family
ID=17638881
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59281418A Granted JPS61154003A (en) | 1984-12-26 | 1984-12-26 | Reduction resisting positive temperature coefficient semiconductor porcelain |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61154003A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3646345B2 (en) * | 1995-04-11 | 2005-05-11 | 株式会社デンソー | Positive temperature coefficient thermistor device |
| JP3047856B2 (en) * | 1997-05-12 | 2000-06-05 | 日本電気株式会社 | Antenna direction adjustment device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5225558A (en) * | 1975-08-22 | 1977-02-25 | Hitachi Ltd | Scanned-point arrangement method |
| JPS5919442A (en) * | 1982-07-22 | 1984-01-31 | Fujitsu Ltd | Radio communication system |
-
1984
- 1984-12-26 JP JP59281418A patent/JPS61154003A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5225558A (en) * | 1975-08-22 | 1977-02-25 | Hitachi Ltd | Scanned-point arrangement method |
| JPS5919442A (en) * | 1982-07-22 | 1984-01-31 | Fujitsu Ltd | Radio communication system |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61154003A (en) | 1986-07-12 |
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