JP4643149B2 - Brazing material - Google Patents

Description

  The present invention relates to a vacuum circuit breaker formed by joining constituent members in a vacuum vessel, and particularly to a brazing material for joining members constituting the vacuum circuit breaker.

  A vacuum circuit breaker is required to maintain welding resistance, withstand voltage characteristics, interruption characteristics, cutting characteristics, wear resistance, contact resistance characteristics, temperature rise characteristics, and the like. However, the vacuum circuit breaker is subjected to various impact stresses such as mechanical shock, electrical shock, and thermal shock that are generated when the current is interrupted and opened / closed. And cause peeling. In particular, the arc generated by the interruption of the large current and the interruption at the time of opening and closing moves to a part such as the furnace inner surface where the arc voltage is low, stagnates and concentrates there, and causes overheating. By heating the furnace inner surface and the like, the joints of the constituent members of the vacuum circuit breaker are indirectly overheated, causing cracks, dropping and peeling of the joints. In addition, when the arc moves, stays and concentrates on the furnace interior surface, metal particles and metal vapor are abnormally released, and the brazing material is overheated and the brazing material component adheres to other parts. .

  Conventionally, 72% by weight silver (Ag) -28% by weight copper (Cu) is used as a brazing material used in a joint portion of a vacuum circuit breaker. However, when 72 wt% Ag-28 wt% Cu is used as the brazing material, the solidus temperature and the liquidus temperature are both 779 ° C., so that the joining operation temperature is limited.

As a joining technique, there is a technique in which a Sn layer is coated on the joint surface of a constituent member of a vacuum circuit breaker with an Ag—Cu—tin (Sn) brazing material interposed (see, for example, Patent Document 1). Moreover, there exists a joining technique using the brazing material which consists of 5-20% lead (Pb) and the remainder Ag and Cu (for example, refer patent document 2).
JP 59-175521 A JP-A 64-8412

  In the conventional technology for joining components of a vacuum circuit breaker, cracking, dropping and peeling of joints are caused by severe mechanical, electrical, and thermal shocks when a large current is repeatedly applied for a long time. It cannot be avoided completely. The vacuum circuit breaker cannot maintain the airtightness in the furnace if cracks are generated, dropped, or peeled off at the joints of the constituent members. Further, depending on the brazing material used, the inside of the furnace may be contaminated.

Therefore, the present invention has been made to solve the above-described problems, and avoids the formation, dropout, and peeling of cracks in joints, improves electrical characteristics such as withstand voltage characteristics, and suppresses contamination. An object is to provide a brazing material that can be used .

According to one aspect of the present invention for achieving the above object , the solidus temperature is 700 ° C. or higher, comprising 82 to 91% by weight of Ag, 6 to 7% by weight of Cu, and 2 to 10% by weight of Ni. a first phase is not more than the liquidus temperature 950 ° C., 4 to 5 wt% of Ag, 26 to 32 wt% of Cu, 33-34 wt% of Ni, the balance being Sn, 0.5 to 30 m And a second phase having a particle diameter of 5 to 45 area% with respect to the first phase.

Furthermore, according to another aspect of the present invention, it is composed of 87 to 91% by weight of Ag, 6 to 7% by weight of Cu, and 1 to 5% by weight of Sn. A first phase having a temperature of 950 ° C. or lower, 5.1 to 5.4 % by weight of Ag, 19 to 30% by weight of Cu, 30 to 35 % by weight of Ni, and the balance being Sn, 0.5 to 30 μm And a second phase having a particle diameter of 5 to 45 area% with respect to the first phase.

According to the present invention, it is possible to provide a brazing material capable of avoiding the generation, dropping, and peeling of cracks in a joint, improving electrical characteristics such as withstand voltage characteristics, and suppressing contamination.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  As shown in FIG. 1, the vacuum circuit breaker according to the embodiment of the present invention penetrates the vacuum vessel 10 that can be kept in vacuum, the bellows-shaped bellows 15 provided in the vacuum vessel 10, and the vacuum vessel 10. Then, the fixed shaft 20 having the fixed contact electrode 21 in the vacuum vessel 10, the vacuum vessel 10 is penetrated from the side facing the fixed shaft 20, and disposed through the bellows 15, and the movable contact electrode 31 is placed in the vacuum vessel 10. A movable shaft 30 that allows the fixed contact electrode 21 and the movable contact electrode 31 to be contacted and separated, and an arc shield 40 for interrupting an arc generated between the fixed contact electrode 21 and the movable contact electrode 31; A vacuum vessel 10, a fixed shaft 20, a movable shaft 30, and a bonding phase 50 used for bonding between the arc shield 40 are provided. The bellows 15 has elasticity by having a bellows shape. Therefore, the movable shaft 30 disposed via the bellows 15 is movable, and allows the fixed contact electrode 21 and the movable contact electrode 31 to be contacted and separated. A bellows cover 16 is attached around the bellows 15 provided in the vacuum vessel 10 to protect the vacuum vessel 10.

  The vacuum vessel 10 includes a cylindrical insulating tube 11 having openings at both ends, and first and second sealing fittings 12a and 12b having the same diameter as the insulating tube 11 provided at both ends of the insulating tube 11, A first end plate 13 disposed on the first sealing fitting 12 a provided at one end of the insulating cylinder 11 and sealing the insulating cylinder 11, and a first end plate provided at the other end of the insulating cylinder 11. And a second end plate 14 which is disposed on the second sealing fitting 12b and seals the insulating cylinder 11. The first end plate 13 has a hole for allowing the fixed shaft 20 to pass therethrough. Further, the second end plate 14 has a hole for allowing the movable shaft 30 to pass therethrough.

  For the insulating cylinder 11, ceramics or the like mainly composed of aluminum oxide having heat resistance, chemical resistance, and high electrical insulation can be used. As the first and second sealing fittings 12a and 12b, an alloy such as iron (Fe) -nickel (Ni) -cobalt (Co) alloy (Kovar) can be used. The constituent members for the vacuum circuit breaker such as the fixed shaft 20, the fixed contact electrode 21, the movable shaft 30, the movable contact electrode 31, the bellows 15, the bellows cover 16, and the arc shield 40 are Cu, Cu alloy, Ag alloy, Ni, It is appropriately configured with a metal member such as a Ni alloy and a stainless steel (SUS) member. For example, Cu-tellurium (Te), Cu-tungsten (W), Cu-chromium (Cr), or the like can be used as the Cu alloy. Further, as the Ag alloy, Ag-tungsten carbide (WC) or the like can be used. As the Ni alloy, Cu—Ni, Ni—Cr, Fe—Ni, Fe—Ni—Cr, Kovar, or the like can be used.

  As shown in FIG. 2, the bonding phase 50 is a brazing material comprising a first phase 51 made of Ag and Cu, and a second phase 52 made of at least one of Ag, Cu, and the balance of Ni and Sn. is there. The bonding phase 50 includes a first end plate 13 / first sealing metal fitting 12a, a second end plate 14 / second sealing metal fitting 12b, a fixed shaft 20 / fixed contact electrode 21, a movable shaft 30 / movable contact electrode 31. The bellows 15 / movable shaft 30, the bellows 15 / bellows cover 16, the arc shield 40 / insulating cylinder 11 and the like are joined. A part of the brazing material used as the bonding phase 50 adheres to the fixed contact electrode 21, the movable contact electrode 31, the arc shield 40, and the like when the current exceeding the rated current value is cut off. At the location where the brazing material is adhered, the arc stagnation causes abnormal melting and reaches the cut-off limit, and the voltage resistance decreases. Therefore, there is a need to reduce the amount of brazing material deposited or deposited.

  The first phase 51 is preferably composed of 90 wt% or more of Ag and 10 wt% or less of Cu. The first phase 51 limits the liquidus temperature of the bonding phase 50 to 950 ° C. or lower and the solidus temperature to 700 ° C. or higher. When the liquidus temperature of the brazing material used for the bonding phase 50 is higher than 950 ° C., the contact characteristics are remarkably deteriorated due to evaporation of the contact materials of the fixed contact electrode 21 and the movable contact electrode 31. In addition, when brazing at 950 degrees or more, the structural members of the vacuum circuit breaker recrystallize, excessively coarsening the crystal grains, deteriorating mechanical properties, and accelerating evaporation loss. To shorten the life of the vacuum circuit breaker. On the other hand, when the solidus temperature of the brazing material used for the bonding phase 50 is less than 700 ° C., the surfaces to be bonded of the respective constituent members are not activated, so that bonding becomes impossible. Further, it is not possible to sufficiently remove moisture and gas adhering to the surface of the constituent member. As a result, the vacuum failure and the withstand voltage characteristics of the vacuum circuit breaker are reduced, which is not preferable. The first phase 51 limits the melting temperature of the entire bonding phase 50 to a predetermined range, and as a result of specifying the brazing operation temperature, realizes a high-quality bonding phase 50 such as bonding strength and vacuum tightness.

  Second phase 52 comprises 8 wt% or less, preferably 3.6 wt% to 5.8 wt% Ag, and 5 to 35 wt% Cu. The second phase 52 is present in an amount of 5 to 45 area% with respect to the first phase 51. Components other than Ag and Cu in the second phase 52 are Ni and Sn. For example, as shown in FIG. 2, the second phase 52 is mixed in the first phase 51 as particles having a diameter of 0.5 to 30 μm. When the particle is not spherical, the diameter of the sphere when the volume of the particle is a sphere is used. Alternatively, the second phase 52 forms a structure having a width of 30 μm or less and is mixed in the first phase 51. By changing the ratio of the second phase 52 contained in the first phase 51, the liquidus temperature and the solidus temperature can be adjusted.

  Below, the multi-step brazing method of the brazing material used for the joining phase 50 according to the embodiment of the present invention will be described with reference to FIG.

  (A) First, two types of brazing materials having different liquidus temperature and solidus temperature are prepared by changing the ratio between the first phase and the second phase. For example, the relatively high liquidus temperature and solidus temperature are defined as the first brazing material 80, and the low temperature is defined as the second brazing material 81.

  (B) Next, the first object 90a and the second object 91a are bonded using the first brazing material 80. Similarly, the first workpiece 90 b and the second workpiece 91 b are joined using the first brazing material 80.

  (C) Next, the second object 91a and the third object 92 are bonded using the second brazing material 81. Similarly, the second workpiece 91 b and the third workpiece 92 are joined using the second brazing material 81.

  Even if it joins with the 2nd brazing material 81 at the next step after joining with the 1st brazing material 80 by performing the above-mentioned multi-step brazing, the 1st brazing material 80 is the second brazing material. Since the liquidus temperature and the solidus temperature of the material 81 are higher, the first objects 90a and 90b do not fall. By using multi-step brazing, for example, joint portions of the fixed contact electrode 21 / fixed shaft 20, the movable contact electrode 31 / movable shaft 30, the movable shaft 30 / bellows cover 16, the bellows 15 / bellows cover 16 and the like shown in FIG. Are joined by a first brazing material 80 having a high liquidus temperature and solidus temperature. Next, after these are inserted and arranged inside the insulating cylinder 11, the first end plate 13 / the first sealing metal fitting 12 a and the second end plate are exhausted using the second brazing material 81 while exhausting the inside of the insulating cylinder 11. 14 / The second sealing fitting 12b is hermetically joined. That is, by limiting the liquidus temperature and the solidus temperature, the brazing operation temperature can be specified, and the operation can be simplified.

  According to the brazing material used as the joining phase 50 of the vacuum circuit breaker according to the embodiment, the fixed contact electrode 21 is obtained by forming a composite structure in which the second phase shown in FIG. 2 is dispersed in the first phase. And external contact energy such as mechanical shock, electrical shock, and thermal shock received by the joints of the constituent members of the vacuum circuit breaker when opening and closing and moving contact electrode 31 are opened and closed. Presents a buffering action that is absorbed or reduced by a frictional motion that occurs between the first phase and the second phase. Therefore, the brazing material used as the joining phase 50 maintains airtightness by suppressing the occurrence and progress of cracks in the joining portion, and also ensures the mechanical strength of the joining phase, thereby ensuring the withstand voltage of the vacuum circuit breaker. This contributes to stabilization of electrical characteristics such as characteristics.

  In addition, according to the brazing filler metal according to the embodiment, the ratio between the first phase and the second phase is optimized, and the liquidus temperature is adjusted to 950 ° C. or lower and the solidus temperature is adjusted to 700 ° C. or higher. It is possible to reduce thermal deterioration such as excessive softening of the crystal structure of the constituent members in the circuit breaker, and to secure the bonding characteristics and withstand voltage characteristics of the bonded portion of the vacuum circuit breaker.

  That is, by optimizing the liquidus temperature and the solidus temperature of the brazing material used as the bonding phase 50, the brazing filler metal component is excessively transferred to the fixed contact electrode 21, the movable contact electrode 31, the arc shield 40, and the like. Therefore, the movement of the arc can be easily performed by suppressing the stagnation and concentration of the arc. Therefore, the vacuum circuit breaker can avoid the generation, dropout, and peeling of the joint cracks, and can improve electrical characteristics such as withstand voltage characteristics. Moreover, the brazing material according to the embodiment can be used for joining metal and SUS.

(Example)
Examples and comparative examples actually measured under various conditions are shown below. First, measurement methods and evaluation methods when performing Examples and Comparative Examples are shown.

As the evaluation (1), the bonding characteristics are evaluated. As "joining characteristics", a SUS round bar with a length of 200 mm and a diameter of 30 mm is cut into two equal parts, and a brazing material of each condition is sandwiched between each cut surface, and optimum joining corresponding to each composition in a vacuum atmosphere A temperature (for example, 700 ° C. to 950 ° C.) was selected and bonded. The object to be joined is subjected to 2 × 10 ⁵ times of repeated expansion / contraction operation with an electric coil type testing machine, and then the tensile strength value is measured, and cracking of the joint portion occurs with a 200 × microscope. The situation was observed. The tensile strength was shown as a relative value with respect to the value of Example 2 to be described later, and was used as a standard for “joining characteristics”. The reason why the joint is subjected to a severe expansion and contraction operation of 2 × 10 ⁵ times is that airtightness caused by a micro crack generated in the joint due to a mechanical or thermal external force part at the time of opening and closing and shutting off. This is to see a decrease in the withstand voltage characteristic and the cutoff characteristic due to the decrease. As a result of the evaluation, the relative value with respect to the value of Example 2 is 1.2 times or more A1, 1.0 or more to less than 1.2 times A2, 0.9 to 1.0 times less A3, 0. X is 5 times or more and less than 0.9 times, Y is less than 0.5 times, and Z is poor bonding.

Furthermore, withstand voltage characteristics are evaluated as evaluation (2). With regard to the “withstand voltage characteristics”, the withstand voltage characteristics are evaluated by adjusting the contact electrode surface baking, current, voltage aging, and distance between electrodes to a certain level, and immediately after airtight bonding and after standing for a predetermined period. The operation of gradually increasing the applied voltage from 0 kV to 120 kV was performed 10 times on both ends of the SUS insulating container. When all 10 breakdown voltage values showed 95 kV or more, it was determined as “pass”, and when it was less than 95 kV, it was determined as “fail”. In some tests, airtightness was evaluated. Use a helium (He) leak detector immediately after airtight joining and after leaving for a predetermined period, and use a leak amount of 3.8 × 10 ^-12 (Pa · L / s) or less as a guideline for airtightness “pass” Described.

  For the test vacuum circuit breakers according to each of the examples and comparative examples used for evaluation, cracks and dropouts of parts occurred before the evaluation in order to clarify the respective effects and accelerate the evaluation. Gives no mechanical shock (no voltage / current).

  Among the combinations of the joining portions of the constituent members of the vacuum circuit breaker, the bellows 15 / movable shaft 30, the first end plate 13 / the first sealing fitting 12a, the second end plate 14 / the second sealing Since the bracket 12b and the like are most required to be airtight, this portion is mainly used as an evaluation portion in the evaluation of airtightness.

A vacuum circuit breaker was assembled using the brazing material of each composition shown in FIG. In some tests, for the purpose of clarifying the joining effect of a specific part (for example, the joint of the bellows 15 / movable shaft 30), the other part (for example, the first end plate 13 / the first sealing fitting 12a). In the joining of), joining by molybdenum (Mo) -manganese (Mn) was also added.
(Comparative Example 1, Examples 1-4)
As shown in FIG. 4, in Comparative Example 1 and Examples 1 to 4, the Ag amount in the first layer was set to 70, in order to determine the optimum values of the Ag and Cu amounts in the first phase in the bonding phase. They were changed to 90, 95, 99, and 100% by weight, respectively. The amounts of Ag, Cu, Ni, and Sn in the second phase are almost constant (analytical values: 4.4 to 5.8 wt% Ag, 33.7 to 38.5 wt% Ni, 27.1 to 32.8). Wt% Sn, balance 26.6-33.8 wt% Cu). The particle diameter of the second phase is 15 to 20 μm.

  Evaluation (1): As shown in FIG. 5, the bonding characteristics of Comparative Example 1, Examples 1, 3, and 4 show evaluations A2 and A3 that are equal to or higher than those of the reference material (Example 2). It was good. However, in Comparative Example 1, a decrease in the liquidus temperature value is observed as compared with the reference material, which is not preferable in selecting the joining operation temperature. Therefore, the preferable value of the Ag amount in the first phase is 90 to 100% by weight.

  Evaluation (2): As shown in FIG. 5, the brazing filler metal having an Ag amount of 90 to 100% by weight (Examples 1 to 4) in the first phase, and the brazing material having an Ag amount of 70% by weight (Comparative Example 1). In any case where the material is used, the dielectric breakdown voltage value shows a target of 95 kV or more, and the withstand voltage characteristic is “pass”.

  As a reference, for Examples 1 to 4, even in the investigation results by microscopic observation of the joint portions of the respective constituent members after the blocking test, there is no generation of cracks, and the deterioration of the degree of vacuum shows an allowable range, and good bonding is seen. It was judged as “pass”.

  Although the area of the arced portion of the surface of the stationary contact electrode 21 and the movable contact electrode 21 after the 8 kA was cut off at 7.2 kV and 50 Hz four times and the state of arc expansion were investigated, the arc Good without any local concentration. When a specific element of the constituent element of the brazing material adheres to a part of the surfaces of the fixed contact electrode 21 and the movable contact electrode 31 after being interrupted, generally, an excessive concentration of arc occurs in the segregated element part. there is a possibility. As a result, the segregation element is selectively evaporated, which causes a decrease in voltage resistance due to dielectric breakdown and a decrease in cutoff characteristics. Therefore, it is necessary to prevent as much as possible the situation where the brazing material is scattered and adhered to the surface portions of the fixed contact electrode 21 and the movable contact electrode 31. If there is no segregation of the brazing material on the surface of the contact electrode, the arc exhibits sufficient spreadability, so the arc portion occupies a relatively large area, and the withstand voltage Properties are preferred. These effects mean the result that the first phase and the second phase were in a preferable state, and both showed good arc spreading properties and were good.

(Comparative Example 2, Examples 5 and 6)
As shown in FIG. 4, in Comparative Example 2, Examples 5 and 6, the ratio of the Ag amount to the total amount of Ag and Cu in the first phase is constant at 92 to 93%. The first phase of Comparative Example 2 contains 20% by weight of Ni. The first phase of Example 5 contains 10% by weight of Ni. The first phase of Example 6 contains 2% by weight of Ni. The amounts of Ag, Cu, Ni, and Sn in the second phase are almost constant (analytical values: 3.6 to 5.8 wt% Ag, 33.7 to 38.5 wt% Ni, 27.1 to 32.8). Wt% Sn, balance 26.8 to 33.2 wt% Cu). The particle diameter of the second phase is 15 to 20 μm. That is, Comparative Example 2, Examples 5 and 6 examine the influence of Ni contained in the first phase.

  Evaluation (1): As shown in FIG. 5, the bonding characteristics of Comparative Example 2, Examples 5 and 6 show evaluations A1 to A2 and A2 which are equal to or higher than those of the reference material (Example 2), and are good. there were.

  Evaluation (2): As shown in FIG. 5, the withstand voltage characteristics of Examples 5 and 6 show a dielectric breakdown voltage value of 95 kV or more and are “pass”. On the other hand, in Comparative Example 2 in which the amount of Ni in the first phase is 20% by weight, the dielectric breakdown voltage value is 95 kV or less and is “failed”. In Comparative Example 2, the undissolved portion of Ni remains in the first phase and micro cracks starting from the first phase occur, resulting in a decrease in hermeticity. Results in 95 kV or less. If an attempt is made to eliminate the Ni undissolved portion in the first phase, it is not preferable because it is necessary to increase the bonding operation temperature.

  Therefore, from Comparative Example 2, Examples 5 and 6, the amount of Ni in the first phase is not limited to zero, but a large amount of Ni is not preferable.

(Comparative Example 3, Examples 7-12)
As shown in FIG. 4, in Comparative Example 3 and Examples 7 to 12, the ratio of the Ag amount to the total amount of Ag and Cu in the first phase is kept constant at 92 to 93%. The first phase of Comparative Example 3 contains 15% by weight of Sn. The first phase of Example 7 contains 5% by weight of Sn. The first phase of Example 8 contains 2% by weight of Sn. The first phase of Example 9 contains 2 wt% Ni and 1 wt% Sn. The first phase of Example 10 contains 2 wt% Ni and 5 wt% In. The first phase of Example 11 contains 2 wt% Ni, 3 wt% Sn, and 2 wt% In. The first phase of Example 12 contains 2 wt% Sn and 3 wt% In. The amounts of Ag, Cu, Ni, and Sn in the second phase are almost constant (analytical values: 4.9 to 5.2 wt% Ag, 33.7 to 38.5 wt% Ni, 27.1 to 32.8). Wt% Sn, balance 26.8 to 33.2 wt% Cu). The particle diameter of the second phase is 15 to 20 μm. That is, Comparative Example 3 and Examples 7 to 12 investigate the influence of compositions other than Ag and Cu contained in the first phase.

  Evaluation (1): As shown in FIG. 5, the bonding characteristics of Examples 7 to 12 are equivalent to those of the reference material (Example 2), showing the same evaluation A3, evaluation A2, and evaluation A2 to A3. It was. On the other hand, the tensile strength, which is a measure of the bonding characteristics of Comparative Example 3, is greatly reduced to evaluations Y to Z, and the variation width of the tensile strength is increased, and cracks are observed. It lacks stability.

  Evaluation (2): As shown in FIG. 5, the withstand voltage characteristics of Comparative Example 3 and Examples 7 to 12 indicate a dielectric breakdown voltage value of 95 kV or more and are “pass”.

  As a reference, the bonding state of each component after the interruption test was observed by microscopic observation, and good bonding was observed, cracks were not generated, and the degree of vacuum deterioration was within an allowable range.

  Therefore, from Comparative Example 3 and Examples 7 to 9, the amount of Sn in the first phase is not limited to zero, but a large amount of Sn is not preferable. In addition, when Sn in Example 10 is replaced with In, both Sn and In in Examples 11 and 12 coexist with good junction characteristics and withstand voltage characteristics, and a desired brazing material can be obtained.

(Examples 13 and 14, Comparative Example 4)
As shown in FIG. 4, in Examples 13 and 14 and Comparative Example 4, the ratio of the Ag amount to the total amount of Ag and Cu in the first phase is kept constant at 92 to 93%. In Examples 13 and 14 and Comparative Example 4, the first phase is composed of only Ag and Cu. The second phase of Example 13 does not contain Ag. The second phase of Example 14 contains 8% by weight of Ag. The second phase of Comparative Example 4 contains 15% by weight of Ag. In Examples 13 and 14 and Comparative Example 4, the amount of Cu in the second phase is set to a substantially constant range (26.6 to 33.8% by weight). The particle diameter of the second phase is 15 to 20 μm. That is, Examples 13 and 14 and Comparative Example 4 examine the influence of Ag contained in the second phase.

  Evaluation (1): As shown in FIG. 5, the bonding characteristics of Examples 13 and 14 were good as compared with the reference material (Example 2), showing the same evaluations A2 and A3. On the other hand, the bonding characteristics of Comparative Example 4 are not preferable because they show large variations from Evaluation A3 to Evaluation X and lack the stability of the bonding surface. Further, in Comparative Example 4, as a result of observing the occurrence of cracks in the joint portion with a 200 × microscope, a decrease in wettability of the second phase was observed.

  Evaluation (2): As shown in FIG. 5, the withstand voltage characteristics of Examples 13 and 14 and Comparative Example 4 indicate a dielectric breakdown voltage value of 95 kV or more and are “pass”.

  Therefore, from Examples 13 and 14 and Comparative Example 4, the desired brazing material is obtained when the Ag content in the second phase is not limited to the above range of 3.6 to 5.8% by weight and is 8% by weight or less. .

(Examples 15 to 17, Comparative Examples 5 and 6)
As shown in FIG. 4, in Examples 15 to 17 and Comparative Examples 5 and 6, the ratio of the Ag amount to the total amount of Ag and Cu in the first phase is kept constant at 92 to 93%. In Examples 15 to 17 and Comparative Examples 5 and 6, the first phase is composed only of Ag and Cu. The second phase of Comparative Example 5 does not contain Cu. The second phase of Example 15 contains 5% by weight of Cu. The second phase of Example 16 contains 15.2% by weight of Cu. The second phase of Example 17 contains 35% by weight of Cu. The second phase of Comparative Example 6 contains 55.3% by weight of Cu. In Examples 15 to 17 and Comparative Examples 5 and 6, the amount of Ag in the second phase is set to a substantially constant range (4.4 to 5.8% by weight). The particle diameter of the second phase is 15 to 20 μm. That is, Examples 15 to 17 and Comparative Examples 5 and 6 are for examining the influence of Cu contained in the second phase.

  Evaluation (1): As shown in FIG. 5, the bonding characteristics of Examples 15 to 17 and Comparative Example 6 were the same as those of the reference material (Example 2), showing the same evaluations A2 and A1 to A2. It was. On the other hand, the bonding characteristics of Comparative Example 5 are not preferable because they show large variations from Evaluation A3 to Evaluation X and lack the stability of the bonding surface.

  Evaluation (2): As shown in FIG. 5, the withstand voltage characteristics of Examples 15 to 17 indicate a dielectric breakdown voltage value of 95 kV or higher and are “pass”. On the other hand, in Comparative Examples 5 and 6, the dielectric breakdown voltage value is 95 kV or less and is “failed”. In Comparative Examples 5 and 6, the undissolved portion remains in the second phase, micro cracks starting from the second phase are generated, and the hermeticity is lowered. Results in 95 kV or less.

  Therefore, according to Examples 15 to 17 and Comparative Examples 5 and 6, the amount of Cu in the second phase is not limited to the above-mentioned fixed range (26.6 to 33.8% by weight), but is desired when it is 35% by weight or less. A material is obtained.

  Note that, in the interruption test conducted as a reference, brazing material in the vicinity of the arc portion of the surface of the fixed contact electrode 21 and the movable contact electrode 31 after interruption of a current lower than the rated current value (for example, 8 kA) four times. Although the distribution of components was investigated, there was no segregation of specific elements among the constituent elements in the brazing filler metal, and the arc did not appear to be concentrated locally. It was good.

(Examples 18 and 19, Comparative Examples 7 and 8)
As shown in FIG. 4, in Examples 18 and 19 and Comparative Examples 7 and 8, the ratio of the Ag amount to the total amount of Ag and Cu in the first phase is kept constant at 92 to 93%. In Examples 18 and 19 and Comparative Examples 7 and 8, the first phase is composed only of Ag and Cu. The second phase of Comparative Example 7 contains 16.5% by weight of Ni. The second phase of Example 18 contains 25% by weight of Ni. The second phase of Example 19 contains 65% by weight of Ni. The second phase of Comparative Example 8 contains 75.4% by weight of Ni. In Examples 18 and 19 and Comparative Examples 7 and 8, the amount of Ag in the second phase is set to a substantially constant range (3.6 to 5.3% by weight). The particle diameter of the second phase is 15 to 20 μm. That is, Examples 18 and 19 and Comparative Examples 7 and 8 investigate the influence of Ni contained in the second phase.

  Evaluation (1): As shown in FIG. 5, the bonding characteristics of Examples 18 and 19 and Comparative Example 7 were good and showed the same evaluations A2 and A3 as compared with the reference material (Example 2). On the other hand, the bonding characteristics of Comparative Example 8 are not preferable because they show Evaluation X and lack the stability of the bonding surface.

  Evaluation (2): As shown in FIG. 5, the withstand voltage characteristics of Examples 18 and 19 and Comparative Examples 7 and 8 show a dielectric breakdown voltage value of 95 kV or more and are “pass”.

  However, Comparative Example 7 is not preferable because the solidus temperature of the second phase itself is excessively lowered. In Comparative Example 9, the liquidus temperature of the second phase itself rises excessively, leading to an increase in the joining operation temperature, which is not preferable. Therefore, from Examples 18 and 19 and Comparative Examples 7 and 8, the Ni amount in the second phase is in the range of 25.0 wt% to 65.0 wt%, and the desired soldering excellent in the bonding characteristics and the withstand voltage characteristics. A material can be obtained.

(Examples 20 to 22, Comparative Examples 9 and 10)
As shown in FIG. 4, in Examples 20 to 22 and Comparative Examples 9 and 10, the ratio of the Ag amount to the total amount of Ag and Cu in the first phase is kept constant at 92 to 93%. In Examples 20 to 22 and Comparative Examples 9 and 10, the first phase is composed only of Ag and Cu. The second phase of Comparative Example 9 contains 15.6% by weight of Sn. The second phase of Example 20 contains 20% by weight of Sn. The second phase of Example 21 contains 37.5% by weight of Sn. The second phase of Example 22 contains 55% by weight of Sn. The second phase of Comparative Example 10 contains 65.4% by weight of Sn. In Examples 20 to 22 and Comparative Examples 9 and 10, the amount of Ag in the second phase is set to a substantially constant range (4.7 to 5.8% by weight). The particle diameter of the second phase is 15 to 20 μm. That is, Examples 20 to 22 and Comparative Examples 9 and 10 examine the influence of Sn contained in the second phase.

  Evaluation (1): As shown in FIG. 5, the bonding characteristics of Examples 20 to 22 and Comparative Example 9 were the same as those of the reference material (Example 2), showing the same evaluations A2 and A3. On the other hand, the bonding characteristics of Comparative Example 10 are not preferable because they show evaluation Z and lack the stability of the bonding surface.

  Evaluation (2): As shown in FIG. 5, the withstand voltage characteristics of Examples 20 to 22 and Comparative Example 9 show a dielectric breakdown voltage value of 95 kV or more and are “pass”. On the other hand, in the comparative example 10, the dielectric breakdown voltage value is 95 kV or less and is “fail”.

  Comparative Example 9 is excellent in bonding characteristics and withstand voltage characteristics, but is not preferable because a decrease in the second-phase solidus temperature and an increase in the liquidus temperature are observed. Comparative Example 10 is not preferable because it not only has low bonding characteristics and withstand voltage characteristics, but also causes an excessive decrease in the solidus temperature of the second phase. Therefore, from Examples 20 to 22 and Comparative Examples 9 and 10, the Sn amount in the second phase is in the range of 20.0 wt% to 55.0 wt%, and the desired soldering excellent in bonding characteristics and withstand voltage characteristics A material can be obtained.

(Examples 23 to 25, Comparative Examples 11 and 12)
As shown in FIG. 4, in Examples 20 to 22 and Comparative Examples 9 and 10, the ratio of the Ag amount to the total amount of Ag and Cu in the first phase is kept constant at 92 to 93%. In Examples 20 to 22 and Comparative Examples 9 and 10, the first phase is composed only of Ag and Cu. The amounts of Ag, Cu, Ni and Sn in the second phase are almost constant (analytical values: 5.2 to 5.6 wt% Ag, 32.8 to 34.1 wt% Ni, 29.1 to 31.5). Wt% Sn, balance 29.2 to 32.2 wt% Cu). In Example 23, the particle diameter of the second phase is 5 to 15 μm. In Example 25, the particle diameter of the second phase is 0.5 to 3 μm. In Example 24, the particle diameter of the second phase is 20 to 30 μm. In Comparative Example 11, the particle diameter of the second phase is 50 μm or more. In Comparative Example 12, the particle diameter of the second phase is 0.01 to 0.3 μm. That is, in Examples 23 to 25 and Comparative Examples 11 and 12, the composition of the first and second phases is made substantially the same, and the particle diameter of the second phase is changed to examine the influence of the particle diameter of the second phase. Is.

  Evaluation (1): As shown in FIG. 5, the bonding characteristics of Examples 23 to 25 were the same as those of the reference material (Example 2), showing the same evaluations A1 to A2, A2 to A3, and A1. It was. On the other hand, the bonding characteristics of Comparative Examples 11 and 12 are not preferable because they show large variations in evaluations A2 to Z and A2 to Y and lack the stability of the bonding surface.

  Evaluation (2): As shown in FIG. 5, the withstand voltage characteristics of Examples 23 to 25 indicate a dielectric breakdown voltage value of 95 kV or more and are “pass”. On the other hand, in Comparative Examples 11 and 12, the dielectric breakdown voltage value is 95 kV or less, which is “fail”.

Comparative Example 11 is not preferable because not only the bonding characteristics and the withstand voltage characteristics are low, but also an excessive decrease in the solidus temperature of the second phase is further observed. As a result of the microscopic observation of the second phase portion of the bonded phase using Comparative Example 11 after the interruption test, there was a crack in a part of the second phase, and the progress of this crack was caused by a decrease in bonding strength and airtightness. This is considered to be a cause of a decrease in withstand voltage characteristics. It is difficult to control the liquidus and solidus temperatures to target values, and the withstand voltage characteristics vary, which is not preferable. Therefore, from Examples 23 to 25 and Comparative Examples 11 and 12, the particle diameter of the second phase is 0. A desired brazing material excellent in bonding characteristics and withstand voltage characteristics can be obtained in the range of 5 to 30 μm.

(Other embodiments)
As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operational techniques should be apparent to those skilled in the art.

  In the embodiment, it is described that multi-step brazing is used as a joining method of the vacuum circuit breaker. However, all joining portions are joined by one kind of brazing material, and the exhaust of the insulating cylinder 11 is an exhaust pipe (not shown). Alternatively, a connection method may be used in which the exhaust pipe portion is chipped off after exhausting. Further, there is a connection method in which the insulating cylinder 11 is exhausted and hermetically joined without using an exhaust pipe with one type of brazing material.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

It is a typical sectional view of the vacuum circuit breaker concerning an embodiment of the invention. It is a conceptual top view when a 2nd phase exists in a 1st phase. It is a schematic diagram for demonstrating multistage step brazing. It is the table | surface which showed the composition of each Example and the comparative example. It is the table | surface which showed the result of the characteristic of an Example and each comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Vacuum container 11 ... Insulating cylinder 12a ... 1st sealing metal fitting 12b ... 2nd sealing metal fitting 13 ... 1st end plate 14 ... 2nd end plate 15 ... Bellows 16 ... Bellows cover 20 ... Fixed shaft 21 ... Fixed Contact electrode 30 ... movable shaft 31 ... movable contact electrode 40 ... arc shield 50 ... joining phase 51 ... first phase 52 ... second phase 80 ... first brazing material 81 ... second brazing material 90a ... first joined Object 90b ... first object to be bonded 91a ... second object to be bonded 91b ... second object to be bonded 92 ... third object to be bonded

Claims (2)

A first phase consisting of 82-91 wt% Ag, 6-7 wt% Cu, 2-10 wt% Ni, having a solidus temperature of 700 ° C or higher and a liquidus temperature of 950 ° C or lower;
4-5 wt% Ag, 26-32 wt% Cu, 33-34 wt% Ni, the balance consisting of Sn, the second phase having a particle diameter of 0.5-30 μm,
The brazing material, wherein the second phase is present in an amount of 5 to 45 area% with respect to the first phase. A first phase consisting of 87-91 wt% Ag, 6-7 wt% Cu, 1-5 wt% Sn, having a solidus temperature of 700 ° C or higher and a liquidus temperature of 950 ° C or lower;
5.1-5.4 wt% Ag, 19-30 wt% Cu, 30-35 wt% Ni, the balance being Sn, the second phase having a particle diameter of 0.5-30 μm ,
The brazing material, wherein the second phase is present in an amount of 5 to 45 area% with respect to the first phase.

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