【発明の詳細な説明】[Detailed description of the invention]
本発明は電気接点材料、特に、耐溶着性に優れ
無害な電気接点用焼結材料に関する。
従来、中負荷領域の電気接点材料として汎用さ
れているAgCdO系焼結材料は、優れた接点性能
を有しているが、有害なCdを原料とするためそ
の製造工程および使用中にCdを含有する粉塵と
なつて公害を発生する恐れがあり、しかもAg含
有量が多い為コストが高いという欠点もあつた。
他方、Cdを含有しない無害な電気接点材料とし
てAgNi系焼結材料が実用化されているが、この
AgNi系焼結材料はAgCdO系のものに比べ耐溶着
性において劣るという問題があつた。
本発明は、従来のAgNi系焼結材料の欠点であ
る耐溶着性を向上させると共に、AgCdO系電気
接点材料とほぼ同等の接点性能を有する安価な電
気接点材料を提供することを目的とするものであ
る。
本発明の要旨は、Ni10〜30％、Cu1.7〜10％、
Ｃ 0.1〜0.5％、残部実質的にAgおよび不可避的
不純物からなる電気接点用焼結材料にある。
本発明に係る電気接点用焼結材料の成分組成を
前記のように限定した理由について説明すると、
Niは耐消耗性を向上させるために添加されるが、
Niが10％未満ではその効果が得られず、また30
％を越えると接触抵抗が増大するので、10〜30％
とした。Cuは接触抵抗とNiの分散性を向上させ
るために添加されるもので、その添加量が1.7％
未満ではNiの分散性の改善がみられず、10％を
越えると耐溶着性が劣化するので1.7〜10％とし
た。また、Ｃは耐溶着性を向上させるために添加
されるもので、その添加量が0.1％未満ではその
添加効果が充分に達成されず、0.5％を越えると
加工性が悪くなるので0.1〜0.5％とした。
前記成分組成の本発明に係る電気接点用焼結材
料は、従来のAgNi系焼結材料に比べ耐溶着性が
大幅に改善され、AgCdO系焼結材料とほぼ同等
の耐溶着性を示す。また、接触抵抗に関しては、
AgにNiを添加すると接触抵抗が増大するが、Cu
およびＣを併添加して共存させつつ焼結すること
により、AgCdO系のものよりも小さくすること
ができる。さらに、耐消耗性に関してはAgCdO
系のものに比べて若干劣るが実用上問題となる程
度の差ではない。しかも、本発明に係る電気接点
用焼結材料は、AgCdO系焼結材料に比べAg含有
量を低減できるので安価に製造することができ、
有害なCdを含有しないので公害発生の原因とな
ることがない。
前記電気接点用焼結材料は、原料としてAg，
Ni，CuおよびＣの各微粉末を用い、これらを所
定比で配合し、加圧成形後、不活性ガス雰囲気中
700〜800℃で１〜20時間焼結する方法により製造
される。また、焼結後、得られた焼結体にサイジ
ング、コイニングなどの再加工を施すのが、好ま
しい。
原料粉末としては、通常、0.1〜103μ、好まし
くは0.5〜20μのものが使用できるが、これらは市
販のものをそのまま使用すればよい。
以下、本発明の実施例について説明する。
実施例
原料粉末をAg粉末（平均粒径：1.08μ）70重量
％、Ni粉末（平均粒径：2.2μ）19.7重量％、Cu
粉末（平均粒径：5μ）10重量％、Ｃ粉末（平均
粒径：5μ）0.3重量％の割合で配合してボールミ
ルにて均一に混合し、その混合粉末を4t／cm2の圧
力下で直径20mm、長さ30mmに成形し、得られた成
形体を不活性ガス雰囲気中750℃で２時間加熱し
て焼結させ電気接点用焼結体を得た。この焼結体
を700〜800℃に加熱し、押出機を用いて直径６mm
の棒状体に成形した後、伸線ヘツダーにて加工し
て得た接点をリレーに組み込み、供試品とした。
比較例 １
原料として実施例で用いたAgとCdOとの粉末
を用い、実施例と同様にしてAg−12％CdOから
なる焼結体を得て接点となし、これをリレーに組
み込み供試品とした。
比較例 ２
原料として実施例で用いたAgおよびNiの粉末
を用い、これらをAg70％、Ni30％の重量比で混
合し、実施例と同様にしてAgNi系焼結体を得て
接点となし、これをリレーに組み込み供試品とし
た。
前記実施例および比較例で得たリレーについ
て、下記の条件で接触抵抗、耐消耗性および溶着
特性を測定した。それらの結果を表に示す。な
お、耐消耗性については35万回開閉動作させた
時、接点の接触力が５ｇ以下になつたリレーの個
数で表わしてある。
［試験条件］
試供品：リレー（2C）各５個
電圧：AC100V
電流：7A
負荷：抵抗負荷
接触力：初期20〜30ｇ
開閉頻度：30回／分
The present invention relates to an electrical contact material, and in particular to a harmless sintered material for electrical contacts that has excellent welding resistance. Conventionally, AgCdO-based sintered materials, which have been widely used as electrical contact materials in the medium load range, have excellent contact performance, but because they are made from harmful Cd, they contain Cd during the manufacturing process and during use. There is a risk that it will turn into dust and cause pollution, and it also has the disadvantage of being expensive due to the high Ag content.
On the other hand, AgNi-based sintered materials have been put into practical use as harmless electrical contact materials that do not contain Cd.
AgNi-based sintered materials have a problem in that they have inferior adhesion resistance compared to AgCdO-based materials. The purpose of the present invention is to improve the welding resistance, which is a drawback of conventional AgNi-based sintered materials, and to provide an inexpensive electrical contact material that has almost the same contact performance as AgCdO-based electrical contact materials. It is. The gist of the present invention is that Ni10-30%, Cu1.7-10%,
The sintered material for electrical contacts consists of 0.1 to 0.5% C, and the remainder essentially consists of Ag and unavoidable impurities. The reason why the composition of the sintered material for electrical contacts according to the present invention is limited as described above is as follows.
Ni is added to improve wear resistance, but
If Ni is less than 10%, this effect cannot be obtained, and if Ni is less than 10%,
If it exceeds 10% to 30%, the contact resistance will increase.
And so. Cu is added to improve contact resistance and Ni dispersibility, and the amount added is 1.7%.
If it is less than 10%, no improvement in the dispersibility of Ni is observed, and if it exceeds 10%, the welding resistance deteriorates, so it is set at 1.7 to 10%. In addition, C is added to improve welding resistance, and if the amount added is less than 0.1%, the effect of addition will not be fully achieved, and if it exceeds 0.5%, workability will deteriorate, so 0.1 to 0.5 %. The sintered material for electrical contacts according to the present invention having the above-mentioned composition has greatly improved adhesion resistance compared to conventional AgNi-based sintered materials, and exhibits adhesion resistance almost equivalent to that of AgCdO-based sintered materials. Regarding contact resistance,
Adding Ni to Ag increases contact resistance, but Cu
By adding and sintering C while making them coexist, the size can be made smaller than that of the AgCdO type. Furthermore, regarding wear resistance, AgCdO
Although it is slightly inferior to the other systems, it is not a difference that would cause a practical problem. Moreover, the sintered material for electrical contacts according to the present invention can be manufactured at low cost because it can reduce the Ag content compared to AgCdO-based sintered materials.
Since it does not contain harmful Cd, it does not cause pollution. The sintered material for electrical contacts uses Ag,
Using fine powders of Ni, Cu, and C, these are mixed in a predetermined ratio, and after pressure molding, it is placed in an inert gas atmosphere.
Manufactured by sintering at 700-800°C for 1-20 hours. Further, after sintering, it is preferable to subject the obtained sintered body to reprocessing such as sizing and coining. As the raw material powder, powders of 0.1 to 10 3 μm, preferably 0.5 to 20 μm can be used, and commercially available powders may be used as they are. Examples of the present invention will be described below. Example Raw material powders were Ag powder (average particle size: 1.08μ) 70% by weight, Ni powder (average particle size: 2.2μ) 19.7% by weight, Cu
Blend 10% by weight of powder (average particle size: 5μ) and 0.3% by weight of C powder (average particle size: 5μ), mix uniformly in a ball mill, and press the mixed powder under a pressure of 4t/ cm2. The molded body was molded into a diameter of 20 mm and a length of 30 mm, and the resulting molded body was heated and sintered at 750° C. for 2 hours in an inert gas atmosphere to obtain a sintered body for an electrical contact. This sintered body was heated to 700 to 800℃ and extruded to a diameter of 6 mm.
After forming the wire into a rod-shaped body, the contacts were processed using a wire drawing header and assembled into a relay to make a sample. Comparative Example 1 Using the Ag and CdO powder used in the example as raw materials, a sintered body of Ag-12%CdO was obtained in the same manner as in the example and used as a contact, and this was incorporated into a relay to make a sample. And so. Comparative Example 2 Using the Ag and Ni powders used in the examples as raw materials, they were mixed at a weight ratio of 70% Ag and 30% Ni, and in the same manner as in the examples, an AgNi-based sintered body was obtained and used as a contact, This was assembled into a relay and used as a sample. Contact resistance, wear resistance, and welding characteristics of the relays obtained in the Examples and Comparative Examples were measured under the following conditions. The results are shown in the table. In addition, wear resistance is expressed as the number of relays whose contact force was 5 g or less after 350,000 opening and closing operations. [Test conditions] Sample: 5 relays (2C) each Voltage: AC100V Current: 7A Load: Resistive load Contact force: Initial 20-30g Opening/closing frequency: 30 times/min
【表】
表１に示す結果から明らかなように、本発明に
係る電気接点材料は、比較例２のものに比べ耐溶
着性が大幅に改善され、比較例１のものとほぼ同
等の特性を示している。また、接触抵抗について
は、比較例１，２よりも秀れた特性を示してい
る。さらに、耐消耗性については、比較例１およ
び比較例２のものに比べて若干劣るものの、実用
上あまり問題とならない程度の差であることがわ
かる。[Table] As is clear from the results shown in Table 1, the electrical contact material according to the present invention has significantly improved welding resistance compared to that of Comparative Example 2, and has almost the same characteristics as that of Comparative Example 1. It shows. Furthermore, regarding contact resistance, it shows better characteristics than Comparative Examples 1 and 2. Furthermore, it can be seen that although the abrasion resistance is slightly inferior to that of Comparative Examples 1 and 2, the difference is such that it does not pose much of a problem in practice.