| An electrical contact point is an important component that most represents the characteristics of electrical energy. The strength of electrical energy is that its flow can be easily controlled with a small force regardless of the volume of energy. An electrical contact point electrically switches on or off the contact for control purposes. An electrical contact point is widely used in many applications such as switches, relays, gateways, security equipment, commutator parts, circuit breakers, electrical and electronic components, communication equipment, elevators and automobile parts. When using a contact point, electrical, mechanical and chemical reactions must be carefully considered. It must be noted that the improper use of a contact point can cause a malfunction of the whole system. |
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â Requirements of Contact Points |
1. Low and stable contact resistance.
2. Easily mountable, with a definite open/close function.
3. Excellent electrical and heat conductivity.
4. Durable, and little deformation of contact surface.
5. Non-transferable and less consuming. |
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â Requirements of Contact Points |
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1. Solid Type: The single element metallic contact point is the most widely used.
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D±0.1
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T±0.05
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d+0/-0.05
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L±0.1
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F
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R
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2.0
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0.5
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1.2
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1.5
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F
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3
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2.0
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0.6
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1.2
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1.5
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F
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3
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2.5
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0.8
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1.5
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1.5
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F
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3
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3.0
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0.8
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1.5
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1.5
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F
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8
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3.0
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1.0
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1.5
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1.5
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F
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8
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3.5
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0.8
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2.0
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2.0
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F
|
10
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3.5
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1.0
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2.0
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2.0
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F
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10
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4.0
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1.0
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2.0
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2.0
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F
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10
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4.0
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1.2
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2.0
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2.0
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F
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10
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4.5
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1.0
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2.5
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2.5
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F
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15
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4.5
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1.2
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2.5
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2.5
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F
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15
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5.0
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1.2
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2.5
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2.5
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F
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20
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6.0
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1.5
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3.0
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2.0
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F
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20
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| 2. Clad Type: The composite contact point reduces costs for greater economy. |
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D±0.1
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T±0.05
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d+0/-0.05
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L±0.1
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t
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F
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R
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2.4
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0.7
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1.2
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1.0
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F
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3
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3.0
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1.0
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1.5
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2.0
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F
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3
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3.5
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1.0
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2.0
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2.0
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F
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3
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4.0
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1.0
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2.0
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2.0
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F
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8
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5.0
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1.0
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2.5
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2.0
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F
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8
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4.0
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1.0
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2.0
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1.8
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1.6
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F
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10
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4.5
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1.0
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2.5
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1.8
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2.1
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F
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10
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5.0
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1.0
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2.5
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2.1
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F
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10
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â Contact Point Materials |
1. Ag-Ni Type Contact Point
Ag and Ni are mostly manufactured through powder metallurgy. The Ag-Ni type is similar to the
AGCDO alloy. Although its seizure resistance is somewhat lower, it is stable because there is less
contact resistance during opening and closing. It is also less consumable by Arc compared to the
Ag-W type, and can resist the load better than the Ag-Cu-Ni alloy. For the Ag-Ni type contact point,
a 10% alloy is the mostly widely used.
2. Ag-Cu Type Contact Point
The Ag-Cu type contact point is more hardened and offers lower conductivity. However, it has higher resistance against acid. The Ag-Cu type contact point has higher contact pressure than Ag and is used
in devices that can be operated even with a temperature increase on the contact surface. A Cu
3%-40% alloy is most widely used. The 92.5% Ag-Cu alloy is widely used for sliding contacts.
3.Ag-CdO Type Contact Point
This type has high seizure resistance durability. The temperature increase during opening and closing
is relatively lower; it also features less contact resistance and has stable properties.
4. Ag-SnO2 Type Contact Point
The new product dramatically increases the product life compared to the Ag-CdO type contact points, enabling a 10-20% reduction of the contact point's size. The environmentally-friendly material is
expected to generate greater demand in the future. |
â Properties of Contact Points |
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Material
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Conductivity
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Specific Gravity
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Tensile Strength
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Operating Rate
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Harness
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Electric
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Heat
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gms/ml
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N/mm2
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%
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HV
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| |
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Soft
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Hard
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Soft
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Hard
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Soft
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Hard
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PURE Gold
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44
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295
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19.3
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140
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240
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30
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1
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25
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70
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PURE Silver
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60
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415
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10.5
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200
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360
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30
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3
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45
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100
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Ag97 Cu3
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52
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375
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10.4
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250
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470
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25
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1
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55
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120
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Ag90 Cu10
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50
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340
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10.3
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280
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550
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15
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1
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70
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140
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Ag90 Ni10
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54
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380
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10.3
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220
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400
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25
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1
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50
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110
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Ag88 CdO12
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48
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340
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10.2
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280
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470
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20
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2
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70
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125
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Ag85 CdO15
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45
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320
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10.1
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295
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480
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15
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1
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80
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130
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Ag92 Sn028
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51
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335
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10
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-
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-
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-
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-
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60
|
90
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Ag90 Sn0210
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48
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325
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9.9
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-
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-
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-
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-
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65
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95
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Ag88 Sn0212
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42
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315
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9.8
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-
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-
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-
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-
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70
|
100
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