【発明の詳細な説明】[Detailed description of the invention]
本発明は内部酸化法によつて製造された銀―酸
化物系の電気接点材料に関する。
従来より内部酸化法によつて製造される銀―酸
化物系の電気接点材料としては銀―酸化カドミウ
ム系が代表的である。これらは小電流乃至中電流
領域で優れた接点性能を示すため各方面で広く使
われてきていた。
然し乍ら、近時電気及び電子機器のより一層の
小型化により電気接点材料にはより高い接点性能
が要求されている。特に銀―酸化カドミウム系の
接点は消耗量が多い為、小型化された部品、例え
ばリレーなどでは絶縁あるいは耐圧不良を起して
しまう。更にカドミウムは人体には有害な金属で
あると言われており、カドミウムを使わず、しか
も接点性能の優れた電気接点材料が要求されてい
るのが現状である。
本発明は上記諸事情に鑑みなされたものであり
従来の銀―酸化カドミウム系に代表される銀―酸
化物系の電気接点材料よりも優れた接点性能、特
に耐消耗性に優れた電気接点材料を提供せんとす
るものである。
本発明は銀―酸化ビスマス―酸化ジルコニウム
合金であつて、内部酸化前の重量比がビスマス１
〜10重量％、ジルコニウム0.5重量％を超え５重
量％まで及び残部銀から成り、かつ、酸化ジルコ
ニウム粒子が銀―ジルコニウム共晶組織の酸化さ
れたものから成るものである。
本発明の電気接点材料において銀中にビスマス
を添加して内部酸化する理由は、酸化ビスマスの
融点が820℃であり熱的には不安定であるため開
閉時の高熱のアークのもとで分解、飛散し同時に
地の銀も飛散させるため接触面の消耗が均一であ
り常に清浄化される。これは接点寿命特に耐溶着
性の向上と接触抵抗の安定化を保つのに優れた効
果がある。反面、消耗量が多くなるという欠点が
ある。この欠点を解消するために更にジルコニウ
ム0.5重量％を超え５重量％まで添加して内部酸
化を行うというのが本発明の特徴である。ジルコ
ニウム0.5重量％を超え５重量％まで添加して酸
化する理由はジルコニウムはビスマスと同様に銀
と共晶を作るためこの３元合金を酸化すると酸化
ビスマスと酸化ジルコニウムが隣接してあるいは
複合酸化物化して銀中に析出する。これによつて
酸化ビスマスの過度な蒸発消耗が防げ、電気接点
材料自身の消耗を抑えるのに効果がある。
かかる効果は銀―ジルコニウム合金の共晶点約
2.5重量％付近の添加量で得られることを本発明
者は見出したが、これは内部酸化後の金属組織が
共晶点近傍組成量を添加したときに均一なものと
なることによるからと思われる。
然して銀中に添加するビスマスを１〜10重量％
とした理由は１重量％未満では酸化ビスマスの特
長を出し切れず10重量％を超えると消耗が極端に
多くなるからである。また添加するジルコニウム
を0.5重量％を超え５重量％までとしたのは0.5重
量％以下では消耗を抑制する効果がなく５重量％
を超えると共晶組織の減少によつてビスマスの耐
溶着特性、低接触抵抗特性を劣化させるからであ
る。
次に本発明による電気接点材料の効果を明瞭な
らしめるためにその具体的な実施例と従来例につ
いて説明する。
実施例 １
銀中にビスマス9.0重量％とジルコニウム0.8重
量％を添加して成る合金の溶湯を金型に鋳造して
直径50mm、長さ45mmのビレツトを作り、次にこの
ビレツトを金型から取外して押出、引抜加工によ
り直径２mmの線材となし、次いでこれを長さ２mm
に切断してチツプを作り、次にこのチツプを９気
圧430℃の酸素雰囲気中で内部酸化して銀―酸化
ビスマス―酸化ジルコニウムの複合体となす。こ
の複合体を圧縮、焼結した後、押出、引抜加工に
より線材を得た後ヘツダー加工に依り頭部直径５
mm、頭部厚さ１mm、脚部径2.5mm、脚部高さ2.5mm
の固定接点と頭部径４mm、頭部厚さ1.1mm、脚部
径2.8mm、脚部高さ1.6mmの可動接点を得た。
実施例 ２
銀中にビスマス4.5重量％とジルコニウム4.0重
量％を添加して成る合金を溶湯噴霧して粒径１mm
以下の粉粒体となし、次に９気圧350℃の酸素雰
囲気中で内部酸化して銀―酸化ビスマス―酸化ジ
ルコニウムの複合粉末となす。次いでこの複合粉
末を圧縮、焼結した後、押出、引抜加工により線
材を得た後ヘツダー加工に依り頭部径５mm、頭部
厚さ１mm、脚部径2.5mm、脚部高さ2.5mmの固定接
点と頭部径４mm、頭部厚さ1.1mm、脚部径2.8mm、
脚部高さ1.6mmの可動接点を得た。
従来例
銀中にカドミウム10.5重量％を添加して成る合
金の溶湯を金型に鋳造して直径50mm、長さ45mmの
ビレツトを作り、次にこのビレツトを金型から取
外して押出、引抜加工に依り、直径２mmの線材と
なし、次いでこれを長さ２mmに切断してチツプを
作り、次にこのチツプを９気圧700℃の酸素雰囲
気中で内部酸化して銀―酸化カドミウムの複合体
となす。この複合体を圧縮、焼結した後、押出、
引抜加工に依り線材を得た後、ヘツダー加工に依
り頭部径５mm、頭部厚さ１mm脚部径2.5mm、脚部
高さ2.5mmの固定接点と頭部径４mm頭部厚さ1.1
mm、脚部径2.8mm、脚部高さ1.6mmの可動接点を得
た。
然してこれら実施例１、２及び従来例の各接点
を夫々18組をリレーに組み込み下記の試験条件に
て溶着回数、絶縁抵抗及び消耗量を測定したとこ
ろ下表に示すような結果を得た。
※ 耐溶着試験条件（18組中９組）
電 圧：AC100V 50Hz
電 流：投入電流 40A
定常電流 10A
負 荷：抵抗負荷
接触力 ：40ｇ
開離力 ：40ｇ
開閉頻度：20回／分
開閉回数：30万回
※消耗量及び絶縁抵抗試験条件（18組中９組）
電 圧：AC100V 50Hz
電 流：30A
負 荷：抵抗負荷
開閉頻度：１回／１秒
接触力 ：40ｇ
開離力 ：100ｇ
開閉回数：20万回
消耗量は接点を取り外し精密天びんにて測定、
絶縁抵抗はDC500Vメガーによる。
The present invention relates to a silver-oxide electrical contact material produced by an internal oxidation method. Conventionally, silver-cadmium oxide type electrical contact materials are typical of silver-oxide type electrical contact materials manufactured by internal oxidation methods. These have been widely used in various fields because they exhibit excellent contact performance in the small to medium current range. However, as electrical and electronic devices have become more compact in recent years, higher contact performance is required of electrical contact materials. In particular, silver-cadmium oxide contacts are subject to a large amount of wear, which can lead to insulation or breakdown voltage failures in miniaturized parts such as relays. Furthermore, cadmium is said to be a metal harmful to the human body, and there is currently a demand for electrical contact materials that do not use cadmium and have excellent contact performance. The present invention has been made in view of the above circumstances, and is an electrical contact material that has superior contact performance, especially wear resistance, than conventional silver-oxide electrical contact materials such as silver-cadmium oxide electrical contact materials. We aim to provide the following. The present invention is a silver-bismuth oxide-zirconium oxide alloy, which has a weight ratio of bismuth 1 before internal oxidation.
-10% by weight of zirconium, more than 0.5% by weight up to 5% by weight of zirconium, and the balance is silver, and the zirconium oxide particles are made of an oxidized silver-zirconium eutectic structure. The reason why bismuth is added to silver and internally oxidized in the electrical contact material of the present invention is that bismuth oxide has a melting point of 820°C and is thermally unstable, so it decomposes under the high-temperature arc during opening and closing. , and the silver on the ground is also scattered at the same time, so the contact surface is uniformly worn and constantly cleaned. This has an excellent effect on contact life, particularly in improving welding resistance and stabilizing contact resistance. On the other hand, it has the disadvantage of increasing consumption. In order to overcome this drawback, the present invention is characterized in that internal oxidation is carried out by adding more than 0.5% by weight of zirconium to 5% by weight. The reason why zirconium is added to more than 0.5% by weight and up to 5% by weight and oxidized is because zirconium forms a eutectic with silver like bismuth, so when this ternary alloy is oxidized, bismuth oxide and zirconium oxide are adjacent to each other or form a composite oxide. and precipitates into silver. This prevents excessive evaporative consumption of bismuth oxide and is effective in suppressing consumption of the electrical contact material itself. This effect is approximately equal to the eutectic point of silver-zirconium alloy.
The present inventor found that it can be obtained with an addition amount of around 2.5% by weight, and this is thought to be because the metal structure after internal oxidation becomes uniform when a composition amount near the eutectic point is added. It will be done. However, the amount of bismuth added to silver is 1 to 10% by weight.
The reason for this is that if it is less than 1% by weight, the characteristics of bismuth oxide cannot be fully exploited, and if it exceeds 10% by weight, consumption becomes extremely high. In addition, the reason for adding zirconium to more than 0.5 wt% and up to 5 wt% is that if it is less than 0.5 wt%, it will not have the effect of suppressing wear.
This is because if it exceeds the eutectic structure, the welding resistance properties and low contact resistance properties of bismuth will deteriorate due to a decrease in the eutectic structure. Next, in order to clarify the effects of the electrical contact material according to the present invention, specific examples and conventional examples thereof will be described. Example 1 A billet with a diameter of 50 mm and a length of 45 mm was made by casting a molten alloy of silver with 9.0% by weight of bismuth and 0.8% by weight of zirconium in a mold, and then this billet was removed from the mold. A wire rod with a diameter of 2 mm is made by extrusion and drawing, and then this is made into a wire rod with a length of 2 mm.
This chip is then internally oxidized in an oxygen atmosphere at 9 atm and 430°C to form a silver-bismuth oxide-zirconium oxide composite. After compressing and sintering this composite, a wire rod was obtained by extrusion and drawing, and then head diameter 5 was obtained by header processing.
mm, head thickness 1mm, leg diameter 2.5mm, leg height 2.5mm
A fixed contact with a head diameter of 4 mm, a head thickness of 1.1 mm, a leg diameter of 2.8 mm, and a movable contact with a leg height of 1.6 mm were obtained. Example 2 An alloy made by adding 4.5% by weight of bismuth and 4.0% by weight of zirconium into silver was sprayed into a molten metal to obtain a particle size of 1 mm.
The following granular material is formed, and then internally oxidized in an oxygen atmosphere at 9 atmospheres and 350°C to form a silver-bismuth oxide-zirconium oxide composite powder. Next, after compressing and sintering this composite powder, a wire rod was obtained by extrusion and drawing, and then header processing was performed to form a wire rod with a head diameter of 5 mm, head thickness of 1 mm, leg diameter of 2.5 mm, and leg height of 2.5 mm. Fixed contact and head diameter 4mm, head thickness 1.1mm, leg diameter 2.8mm,
A movable contact with a leg height of 1.6 mm was obtained. Conventional example A molten alloy made of silver with 10.5% by weight of cadmium added is cast into a mold to create a billet with a diameter of 50 mm and a length of 45 mm.The billet is then removed from the mold and used for extrusion and drawing. Therefore, we made a wire with a diameter of 2 mm, then cut it into 2 mm lengths to make chips, and then internally oxidized the chips in an oxygen atmosphere at 9 atm and 700°C to form a silver-cadmium oxide composite. . After compressing and sintering this composite, extrusion
After obtaining the wire rod by drawing process, head diameter is 5mm, head thickness is 1mm, leg diameter is 2.5mm, leg height is 2.5mm, and fixed contact with head diameter is 4mm and head thickness is 1.1mm by header process.
A movable contact with a leg diameter of 2.8 mm and a leg height of 1.6 mm was obtained. When 18 sets of each of the contacts of Examples 1 and 2 and the conventional example were assembled into a relay and the number of weldings, insulation resistance, and amount of wear were measured under the following test conditions, the results shown in the table below were obtained. * Welding resistance test conditions (9 out of 18 sets) Voltage: AC100V 50Hz Current: Closing current 40A Steady current 10A Load: Resistive load Contact force: 40g Breaking force: 40g Opening/closing frequency: 20 times/min Number of opening/closing: 300,000 times *Consumption amount and insulation resistance test conditions (9 out of 18 sets) Voltage: AC100V 50Hz Current: 30A Load: Resistive load Opening/closing frequency: 1 time/1 second Contact force: 40g Opening force: 100g Opening/closing Number of times: 200,000 times The amount of wear is measured using a precision balance after removing the contacts.
Insulation resistance is determined by DC500V megger.
【表】
上記表で明らかな様に銀―酸化ビスマス―酸化
ジルコニウム電気接点材料は従来多用されている
銀―酸化カドミウム電気接点材料に比し同等ある
いはそれ以上の耐溶着特性を示し、耐消耗性、絶
縁抵抗特性については一段と優れている事がわか
る。
以上詳記した通り、本発明の電気接点材料は耐
溶着性、耐消耗性に優れ、高い絶縁抵抗を示すた
め、小型化が要求されているブレーカー、マグネ
ツトスイツチあるいはリレー等に充分使用できる
ものである。[Table] As is clear from the table above, the silver-bismuth oxide-zirconium oxide electrical contact material exhibits welding resistance equal to or better than that of the conventionally widely used silver-cadmium oxide electrical contact material, and has wear resistance. It can be seen that the insulation resistance characteristics are even better. As detailed above, the electrical contact material of the present invention has excellent welding resistance, wear resistance, and high insulation resistance, so it can be fully used in breakers, magnetic switches, relays, etc. that require miniaturization. It is.