Metal treatment – Stock – Noble metal base
Reexamination Certificate
2002-03-15
2004-06-08
Wyszomierski, George (Department: 1742)
Metal treatment
Stock
Noble metal base
C420S501000, C075S247000
Reexamination Certificate
active
06746551
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to increasing durability of an AC general relay and specifically, in the AC general relay used for a resistive load of about 1 to 20A in the range of AC 100V to 250V, to a make-and-break contact material of Ag—Ni-based alloy with Ni metal particles dispersed therein having excellent endurance compared to a conventional make-and-break contact material of Ag—CdO-based alloy and to a relay using the same.
2. Earlier Technology
An electric contactor which is used for a switching part performing electrical switching through mechanical switching motion is generally called an electric contact. The electric contact requires to transmit a current and signals passing through the contact without any trouble by metal-to-metal contact and to allow itself to be in an open position without any trouble when the metal-to-metal contact is disengaged.
The electric contact has a simple structure, however, it has become common-sense that various physical or chemical phenomena occur on a surface of the contact. The phenomena include, for example, adsorption, oxidation, sulfurization, synthesis of organic compounds, and further, melting, evaporation, ablation, and conversion which entail discharge. These phenomena are significantly complicated and have not yet academically clarified in many parts, and are greatly attributed to the quality of the electric contact material.
Upon occurring these phenomena, a contact function of an electric contact is somewhat disrupted and in some cases the contact function is completely disrupted (e.g., welding), which determines performance and useful life of an electrical appliance incorporating the electric contact. This means that the electric contact is one of the important parts which determine the useful life and performance of the electrical appliances or the like.
In recent years with the significant advancement of electronics and electrical engineering, the scope of application of the electric contact widely varies from an electronic field including a telegraph and telephone and other various electronic equipment to an electric field including electric equipment which interrupts a large current. Therefore, functions to be required vary widely, so that the development of the electric contacts having characteristics adapted to their respective uses is now in progress, and great many kinds of electric contacts are supplied to the market.
In such an electric contact, the technical common-sense having been conventionally known of the AC general relay or switch which is a subject matter of the present invention is as follows. That is, the electric contactor incorporated in the relay or switch is a so-called make-and-break contact. An electric contact material used for this make-and-break contact is in particular required to have wear resistance and transition resistance in order to maintain a stable mechanism and low contact resistivity in order to maintain a stable contact state.
Make-and-break contact materials used for the AC general relays or the like, which are traditionally well known, include an Ag—CdO-based alloy (an alloy comprised of 10 to 15 wt % CdO and a balance being Ag) or the like.
Although each of these electric contact materials may be used alone without being processed, the material may frequently be used after being processed into a two or three layered-type of clad rivet contact in which this material is laminated on Cu or a Cu alloy as a primer or into a two to five layered-type of clad crossbar contact in which this material is laminated on Cu or a Cu alloy as a primer. This clad rivet contact or clad crossbar contact is used being incorporated in the relays, in which electric signals applied in a form of a direct current, an alternating current, or electric impulses generate a coil magnetic flux, and the magnetic force attracts a moving iron, then the electric contact performs switching operations responding to the motion of the moving iron.
This conventional Ag—CdO-based make-and-break contact material satisfies the wear resistance, the transition resistance, and the low contact resistivity at practical levels when using the alternating current load ranging from AC 100 V to 250 V, however, it has been newly pointed out that this material has following problems.
First of all, the conventional make-and-break contact material is not a material adapted to a requirement of a miniaturization. With the enhancement of the functions and performances of the household electrical appliances, the numbers of electric parts to be mounted increase and the miniaturization of the parts themselves is further proceeding. Thus, in spite of being desired to achieve the miniaturization of the relays or switches themselves in consideration of the cost, the conventional make-and-break contact materials cannot sufficiently address the miniaturization.
In other words, if a volume of the make-and-break contact material becomes smaller in order to achieve the miniaturization of the relays, the work load per unit volume of the material largely increases at the time of conduction and interruption of the current, and consequently, the conventional material itself is rapidly worn out, then the failures occur at early stage.
SUMMARY OF THE INVENTION
The present invention is developed against the background of the above described circumstances and to provide a make-and-break contact material which is able to achieve the less wear and to-increase the useful life of the AC general relays even when the miniaturization is achieved, compared with a conventional Ag—CdO-based material.
The inventors have devoted themselves to this development in order to solve above described problems and finally found a make-and-break contact material of Ag—Ni-based alloy with Ni metal particles dispersed therein as follows. That is the make-and-break contact material of Ag—Ni-based alloy which is used for a switching part performing electrical switching through mechanical switching motion, wherein the material with Ni metal particles dispersed therein is obtained by mixing and stirring 3.1 to 20.0 wt % of Ni powder, a certain amount of Li
2
CO
3
powder corresponding to 0.01 to 0.50 wt % of metal Li as an additive, and a balance being Ag powder to form a mixture with the above described powders uniformly dispersed therein, and by subjecting the above described mixture to a compacting process and to a sintering process.
The make-and-break contact material of the present invention is an Ag—Ni-based alloy with Ni metal particles dispersed in an Ag matrix and with Li
2
CO
3
dispersed therein. According to the make-and-break contact material of Ag—Ni-based alloy with Ni metal particles dispersed therein of the present invention, wear resistance, transition resistance, and low contact resistivity are maintained at practical levels in case of an AC load of 1 to 20A in a range from AC 100V to 250V, even when a volume of the make-and-break contact material itself becomes smaller. Consequently, it becomes possible to achieve long-term usage, i.e. the increase in its useful life.
Ni in the make-and-break contact material of Ag—Ni-based alloy with Ni metal particles dispersed therein according to the present invention exists as Ni metal particles in the Ag matrix and contributes to improvement of wear resistance when the material is used for an AC general relay in the range from AC 100V to 250V and from 1 to 20A. When the amount of Ni is less than 3.1 wt %, it becomes difficult to maintain wear resistance of the AC general relay to the practical level, while the amount of Ni exceeds 20.0 wt %, then the problems associated with manufacturing the contacts such as reduction in stability of contact resistance and in workability will occur. In the case of using this material for the AC general relay, it is optimum that the Ni powder in the make-and-break contact material of Ag—Ni-based alloy with Ni metal particles dispersed therein according to the present invention is 8.0 to 15.0 wt %.
Li
2
CO
3
also exists as particles in t
Sakaguchi Osamu
Taneichi Kengo
Yamamoto Toshiya
Combs Morillo Janelle
Rothwell Figg Ernst & Manbeck P.C.
Tanaka Kikinzoku Kogyo K.K.
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