【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−
酸化物系の複合電気接点材料に関する。
内部酸化法によつて製造された銀−酸化物系の
複合電気接点材料としては、従来より銀−酸化カ
ドミウム系の複合電気接点材料が広く用いられて
きた。
この銀−酸化カドミウム系を複合電気接点材料
にて作つた電気接点は、接触抵抗が低く安定して
いて、その上耐溶着性、耐消耗性にも優れている
ので、リレー、コンダクター、安全ブレーカー、
配線用遮断器など小電流域から大電流域にわたり
使用されている。
また前記銀−酸化カドミウム系の複合電気接点
材料は、内部酸化による緻密な酸化物の層が形成
されず、酸化カドミウムの粒子が均一に分散され
ているので、塑性加工し易いものである。
然し乍ら、人体に有害なカドミウムを含む為、
近時その使用をひかえる傾向にある。
この為、銀−酸化カドミウム系の複合電気接点
材料と同等以上の耐溶着性、耐アーク消耗性を有
し且つ接触抵抗が低く安定した銀−酸化物系の複
合電気接点材料の開発が要望されている。
銀−酸化物系の複合電気接点材料の中にはカド
ミウムを用いない接点材料として銀−酸化錫系、
銀−酸化インジウム系、銀−酸化亜鉛系、銀−酸
化マンガン系等の複合電気接点材料がある。
それらの内でも銀−酸化錫系の複合電気接点材
料は、銀−酸化カドミウム系の複合電気接点材料
に比べ耐溶着性に優れているものの内部酸化が非
常に難しい。つまり、溶解して成る銀−錫合金線
材等の内部酸化は緻密な酸化錫の層を作り易い為
低温で内部酸化を行なわなければならず、且つ酸
化速度が極めて遅い。また金属顕微鏡では観察し
得ない程の極めて微細な酸化錫粒子が均一に分散
している為、塑性加工が困難である。
本発明は上記諸事情に鑑みなされたものであ
り、内部酸化を容易ならしめ且つ塑性加工性を向
上させた銀−酸化錫系の複合電気接点材料を提供
せんとするものである。
本発明の複合電気接点材料は、銀中に、錫
7w／ｏを超え12w／ｏ以下とマグネシウム及び
シリコンの少なくとも１種を総量で0.1〜2w／ｏ
を添加して成る銀合金を内部酸化せしめたもので
ある。
銀に錫を添加する他にマグネシウム及びシリコ
ンの少なくとも１種を添加する理由は、これらの
元素が錫と金属間化合物や共晶を形成する為内部
酸化時酸化錫の緻密な層を作ることがなく、高温
で内部酸化することが可能となり、酸化速度も速
くなるからである。また酸化物粒子も適度に成長
し、均一に分散し、塑性加工性が改善されるから
である。
錫の添加量を7w／ｏを超え12w／ｏ以下とし
た理由は、7w／ｏ以下では耐溶着性、耐アーク
消耗性が十分でなく、12w／ｏを超えると酸化物
の体積％が多くなりすぎ、塑性加工が困難となる
為である。またマグネシウム及びシリコンの少な
くとも１種を総量で0.1〜2w／ｏとした理由は、
0.1w／ｏ末満では酸化錫の緻密な層が形成され、
高温で内部酸化することが困難となり且つ酸化速
度も極めて遅くなり、2w／ｏを超えるとより強
固な酸化物の層を作る為塑性加工性が劣下するか
らである。
次に本発明による複合電気接点材料の効果を明
瞭ならしめる為に、その具体的な実施例と従来例
について説明する。
下表の左欄に示す成分組成の実施例１乃至３と
従来例１、２の原材料を溶解し、アトマイズ加工
して1φmm以下の粉粒体となした後下表に示され
る各内部酸化条件にて内部酸化し、これを圧縮、
焼結、押出により線材と成した後硬さ及びヘツダ
ー加工性を調査し、またヘツダー加工によつて得
られた複合電気接点を下記の試験条件にて開閉試
験を行い、溶着発生までの開閉数を測定したとこ
ろ、下表の右欄に示すような結果を得た。
試験条件
電 圧 AC100V50Hz
電 流 投入時71A、定常時5A
開閉頻度 20回／分
開閉数 溶着発生まで
接点寸法 4φmm
The present invention provides silver produced by an internal oxidation method.
This invention relates to oxide-based composite electrical contact materials. Conventionally, silver-cadmium oxide-based composite electrical contact materials have been widely used as silver-oxide-based composite electrical contact materials produced by internal oxidation methods. Electrical contacts made from this silver-cadmium oxide composite electrical contact material have low and stable contact resistance, and also have excellent welding and abrasion resistance, so they can be used in relays, conductors, safety breakers, etc. ,
It is used in molded case circuit breakers and other applications ranging from small current ranges to large current ranges. Further, the silver-cadmium oxide composite electrical contact material does not form a dense oxide layer due to internal oxidation, and the cadmium oxide particles are uniformly dispersed, so it is easy to be plastically worked. However, since it contains cadmium, which is harmful to the human body,
Recently, there has been a tendency to refrain from using it. Therefore, there is a demand for the development of a silver-cadmium oxide-based composite electrical contact material that has welding resistance and arc wear resistance equivalent to or better than silver-cadmium oxide-based composite electrical contact materials, and has low and stable contact resistance. ing. Among the silver-oxide-based composite electrical contact materials, there are silver-tin oxide-based contact materials that do not use cadmium.
There are composite electrical contact materials such as silver-indium oxide, silver-zinc oxide, and silver-manganese oxide. Among these, silver-tin oxide based composite electrical contact materials have superior welding resistance compared to silver-cadmium oxide based composite electrical contact materials, but internal oxidation is extremely difficult. In other words, the internal oxidation of the melted silver-tin alloy wire tends to form a dense layer of tin oxide, so the internal oxidation must be carried out at a low temperature and the oxidation rate is extremely slow. In addition, extremely fine tin oxide particles that cannot be observed with a metallurgical microscope are uniformly dispersed, making plastic working difficult. The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a silver-tin oxide based composite electrical contact material which facilitates internal oxidation and improves plastic workability. The composite electrical contact material of the present invention contains tin in silver.
More than 7 w/o but less than 12 w/o and at least one of magnesium and silicon in a total amount of 0.1 to 2 w/o
It is made by internally oxidizing a silver alloy with the addition of The reason why at least one of magnesium and silicon is added in addition to tin to silver is that these elements form intermetallic compounds or eutectics with tin, making it difficult to form a dense layer of tin oxide during internal oxidation. This is because internal oxidation can be carried out at high temperatures, and the oxidation rate becomes faster. Further, the oxide particles also grow appropriately and are uniformly dispersed, improving plastic workability. The reason why the amount of tin added exceeds 7w/o and is less than 12w/o is that if it is less than 7w/o, the welding resistance and arc wear resistance are insufficient, and if it exceeds 12w/o, the volume percent of oxides will be large. This is because it becomes too hard and makes plastic working difficult. In addition, the reason why the total amount of at least one of magnesium and silicon is 0.1 to 2 w/o is as follows.
At the end of 0.1w/o, a dense layer of tin oxide is formed,
This is because it becomes difficult to internally oxidize at high temperatures and the oxidation rate becomes extremely slow, and if it exceeds 2w/o, a stronger oxide layer is formed, resulting in poor plastic workability. Next, in order to clarify the effects of the composite electrical contact material according to the present invention, specific examples and conventional examples thereof will be described. The raw materials of Examples 1 to 3 and Conventional Examples 1 and 2 with the component compositions shown in the left column of the table below were melted and atomized to form powder of 1φmm or less, and then subjected to the internal oxidation conditions shown in the table below. internally oxidizes and compresses it,
After forming wire rods by sintering and extrusion, we investigated the hardness and header workability, and also conducted opening/closing tests on the composite electrical contacts obtained by header processing under the test conditions below to determine the number of openings and closings until welding occurred. When measured, the results shown in the right column of the table below were obtained. Test conditions Voltage AC100V50Hz Current 71A when turned on, 5A during steady state Opening/closing frequency 20 times/min Number of openings and closings Until welding occurs Contact dimensions 4φmm
【表】
上記の表の右欄の数値で明らかなように本発明
の実施例１乃至３の複合電気接点材料にて作つた
電気接点は、従来例１、２の複合電気接点材料に
て作つた電気接点に比し内部酸化温度を高くする
ことができ、内部酸化に要する時間は1/7に短縮
できた。また硬さはビツカース硬さで100ほど低
くなつており、ヘツダー加工も増面率75％程度で
は割れは発生せず、不良率０％であつた。さらに
溶着発生までの開閉数は従来例のものと同等以上
に多く、マグネシウム及びシリコンの少なくとも
１種を添加することによる耐溶着性の改善が見ら
れる。
尚、上記実施例では合金をアトマイズ加工によ
り粉粒体となし、これを内部酸化した後、圧縮、
焼結、押出により線材となしたが、合金を線材又
は板材に加工した後、内部酸化し、然る後所要の
形状に加工しても良いものである。
以上詳記した通り本発明の複合電気接点材料
は、従来の銀−酸化錫系電気接点材料に比し、内
部酸化が容易であり、塑性加工性に富み、耐溶着
性も改善されているので、従来の銀−酸化錫系電
気接点材料にとつて代わることのできる優れた複
合電気接点材料と言える。[Table] As is clear from the values in the right column of the table above, the electrical contacts made with the composite electrical contact materials of Examples 1 to 3 of the present invention were made with the composite electrical contact materials of Conventional Examples 1 and 2. The internal oxidation temperature can be raised higher than that of conventional electrical contacts, and the time required for internal oxidation can be reduced to 1/7. In addition, the hardness was lower by about 100 on the Vickers scale, and no cracking occurred during header processing at an area increase of about 75%, and the defective rate was 0%. Furthermore, the number of openings and closings until welding occurs is greater than that of the conventional example, indicating that the welding resistance is improved by adding at least one of magnesium and silicon. In the above example, the alloy was made into powder by atomization, and after internal oxidation, compression,
Although wire rods were formed by sintering and extrusion, the alloy may be processed into wire rods or plate materials, internally oxidized, and then processed into the desired shape. As detailed above, the composite electrical contact material of the present invention is easier to internally oxidize, has better plastic workability, and has improved welding resistance than conventional silver-tin oxide electrical contact materials. It can be said that it is an excellent composite electrical contact material that can replace conventional silver-tin oxide based electrical contact materials.