【発明の詳細な説明】[Detailed description of the invention]
本発明は、電気接点材料に関するものである。
従来より電気接点材料としては、銀−金属酸化
物系、銀−ニツケル系、銀−タングステン系、銀
−グラフアイト系などが用いられている。特に、
銀−ニツケル系電気接点材料はニツケル自身が加
工性が良いためニツケル量を増加しても加工性を
損わない。また、接点性能も比較的接触抵抗が低
く安定であり、耐消耗性にも優れているので、数
多く使用されている。ところが、銀−酸化物系の
材料にくらべると、耐溶着性が劣り、かつ、初期
溶着を起こしやすいために使用電流領域が限定し
まうという欠点がある。
本発明は、上記事情に鑑み銀−ニツケル系電気
接点材料の耐溶着性を向上せしめることを目的と
してなされたものである。また、本発明は、銀−
ニツケル系電気接点材料の長所である加工性の良
さ、低く安定した接触抵抗および優れた耐消耗性
を損うことなく、耐溶着性を向上せしめた電気接
点材料を提供することを目的とする。
本発明は、重量比で、ニツケル10〜40％および
炭化タングステン、炭化クロム又は炭化モリブデ
ンの少くとも一種を合計で0.5〜５％、残部銀か
らなることを特徴とする電気接点材料である。
炭化クロム、炭化タングステン又は炭化モリブ
デンは、いずれも非常に硬度が高く、銀ともニツ
ケルともなじみが悪い。そこで、これらの炭化物
を銀−ニツケル合金素材中に均一分散せしめてニ
ツケルの凝集を防ぎ接点性能を向上しようとした
ものである。
ここで、ニツケルの重量％を10〜40％と限定し
たのは、10％未満では耐溶着性が十分でなく、40
％を越えるとニツケルが酸化して酸化ニツケルと
なり接触抵抗が増大するからである。また、炭化
クロム、炭化タングステンまたは炭化モリブデン
は、0.5〜５％の範囲で均等に銀−ニツケル合金
に作用し、いずれの炭化物も耐溶着性を向上させ
る。しかし、総量で0.5％未満では電気接点開閉
時のアーク熱によるニツケルの凝集を防ぐことが
できず、５％を越えると加工性が悪くなり開閉時
の消耗が著しくなるので、これらの炭化物の総量
を0.5〜５％に限定した。
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、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
粒径数＋ミクロン程度の銀粉とニツケル粉と炭
化タングステン粉とを重量比で72.5：25：2.5の
割合で混合した。この混合粉末を圧縮、焼結をく
りかえしたのち、熱間押出、冷間伸線した。そし
て、この線材をヘツダー加工により、頭径４mmφ
の可動接点と頭径５mmφの固定接点を得た。
実施例 ２
粒径百ミクロン程度の銀粉とニツケル粉と炭化
タングステン粉と炭化モリブデン粉とを重量比で
84：15：0.5：0.5の割合で混合した。この混合粉
末を実施例１と同様な方法で、可動接点と固定接
点を得た。
実施例 ３
粒径百ミクロン程度の銀粉とニツケル粉と炭化
クロム粉とを重量比で67：30：３の割合で混合し
た。この混合粉末を実施例１と同様な方法で、可
動接点と固定接点を得た。
従来例 １
粒径数＋ミクロンの銀粉とニツケル粉を重量比
で70：30の割合で混合した。この混合粉未を圧
縮、焼結をくりかえしたのち、熱間押出、冷間伸
線した。そして、この線材をヘツダー加工により
頭径４mmφの可動接点と頭径５mmφの固定接点を
得た。
従来例 ２
粒径百ミクロン程度の銀粉とニツケル粉とを
90：10の割合で混合した。この混合粉末を従来例
１と同様の方法で、可動接点と固定接点を得た。
しかして、実施例１乃至３および従来例１乃至
２のリベツト型電気接点各９個を下記の試験条件
にて開閉試験を行い、耐溶着性と接触抵抗を調べ
たところ下表右欄のような結果を得た。
試験条件
電 圧 AC100V 50Hz
電 流
投入電流 40A 定常電流 5A
開閉頻度 20回／分
負 荷 抵抗
開閉回数 溶着発生まで
The present invention relates to electrical contact materials. Conventionally, as electrical contact materials, silver-metal oxide type, silver-nickel type, silver-tungsten type, silver-graphite type, etc. have been used. especially,
In the silver-nickel electrical contact material, nickel itself has good workability, so even if the amount of nickel is increased, the workability is not impaired. In addition, the contact performance is relatively low and stable, and it has excellent wear resistance, so it is widely used. However, compared to silver-oxide materials, they have the disadvantage that they have poorer welding resistance and are more likely to cause initial welding, which limits the usable current range. The present invention has been made in view of the above circumstances with the object of improving the welding resistance of silver-nickel electrical contact materials. Moreover, the present invention also provides silver-
The purpose of the present invention is to provide an electrical contact material with improved welding resistance without impairing the advantages of nickel-based electrical contact materials, such as good workability, low and stable contact resistance, and excellent wear resistance. The present invention is an electrical contact material characterized by comprising, by weight, 10 to 40% of nickel, a total of 0.5 to 5% of at least one of tungsten carbide, chromium carbide, or molybdenum carbide, and the balance being silver. Chromium carbide, tungsten carbide, and molybdenum carbide all have extremely high hardness and are poorly compatible with silver and nickel. Therefore, an attempt was made to uniformly disperse these carbides in a silver-nickel alloy material to prevent nickel agglomeration and improve contact performance. Here, we limited the weight percentage of nickel to 10 to 40% because if it is less than 10%, the welding resistance is insufficient.
%, nickel will oxidize and become nickel oxide, resulting in an increase in contact resistance. Further, chromium carbide, tungsten carbide, or molybdenum carbide acts equally on the silver-nickel alloy in the range of 0.5 to 5%, and any of the carbides improves the welding resistance. However, if the total amount is less than 0.5%, it will not be possible to prevent the agglomeration of nickel due to arc heat during the opening and closing of electrical contacts, and if it exceeds 5%, workability will deteriorate and wear during opening and closing will become significant. was limited to 0.5% to 5%. 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 Silver powder, nickel powder, and tungsten carbide powder each having a particle size of several microns were mixed in a weight ratio of 72.5:25:2.5. This mixed powder was repeatedly compressed and sintered, then hot extruded and cold wire drawn. Then, this wire is processed into a header with a head diameter of 4mmφ.
A movable contact and a fixed contact with a head diameter of 5 mmφ were obtained. Example 2 Silver powder, nickel powder, tungsten carbide powder, and molybdenum carbide powder with a particle size of about 100 microns were mixed in weight ratio.
Mixed at a ratio of 84:15:0.5:0.5. A movable contact and a fixed contact were obtained using this mixed powder in the same manner as in Example 1. Example 3 Silver powder, nickel powder, and chromium carbide powder each having a particle size of about 100 microns were mixed in a weight ratio of 67:30:3. A movable contact and a fixed contact were obtained using this mixed powder in the same manner as in Example 1. Conventional Example 1 Silver powder and nickel powder with a particle diameter of several microns were mixed at a weight ratio of 70:30. This mixed powder was repeatedly compressed and sintered, then hot extruded and cold wire drawn. Then, this wire was subjected to header processing to obtain a movable contact with a head diameter of 4 mmφ and a fixed contact with a head diameter of 5 mmφ. Conventional example 2 Silver powder and nickel powder with a particle size of about 100 microns are
Mixed at a ratio of 90:10. A movable contact and a fixed contact were obtained using this mixed powder in the same manner as in Conventional Example 1. Therefore, nine rivet-type electrical contacts of Examples 1 to 3 and Conventional Examples 1 to 2 were subjected to opening/closing tests under the following test conditions, and the welding resistance and contact resistance were investigated as shown in the right column of the table below. I got good results. Test conditions Voltage AC100V 50Hz Current Closing current 40A Steady current 5A Opening/closing frequency 20 times/min Load Resistance Number of opening/closing Until welding occurs
【表】
上記表の右欄の結果からあきらかなように、本
発明の電気接点材料でつくつた電気接点は、従来
の電気接点に比し溶着発生までの開閉回数よりは
るかに多く、耐溶着性にすぐれていることがわか
る。また、接触抵抗についても従来例とかわらず
低く安定していることがわかる。
以上の説明からあきらかなように、本発明の電
気接点材料は、従来の電気接料に比し耐溶着性に
すぐれた画期的な発明であるといえる。[Table] As is clear from the results in the right column of the table above, the electrical contacts made using the electrical contact material of the present invention have a much greater number of openings and closings than conventional electrical contacts before welding occurs, and are more resistant to welding. It can be seen that it is excellent. Further, it can be seen that the contact resistance is also low and stable as in the conventional example. As is clear from the above description, the electrical contact material of the present invention can be said to be an epoch-making invention that has superior welding resistance compared to conventional electrical contacts.