Electrical Contacts and points
If the concentration of the nitric is high, it can take longer to dissolve silver, when 68% nitric is diluted 50/50 with water it will react faster.
Some metals can be difficult or passivate in nitric acid.
Note contacts and points can have some dangerous metals to work with; melting can make for some very dangerous gases.
Electrical contacts and points can be made from many different silver/metal compositions, there are many metals that can be used.
Base metals, as well as valuable metals, even Gold and the platinum group metals, can be plated or in the alloys.
Dangerous metals can also be involved in the compositions of these alloys...
Relay contact point's, switches, circuit breakers and the like, will usually contain other metals, some of higher value than just the silver.
Group1: Ag-Mo, Ag-Cu, Ag-Cd, Ag-Fe, Ag-Ni, Ag-Wc, Ag-C
Group2: Ag-Cu-Ni, Ag-Cd-Ni, Ag-Ni-Mg, Ag-Fe-Cu, Ag-CdO
Group3: Ag-Au, Ag-Pt, Ag-Pd
Group4: Cu-W, Cu-WC
Normally silver is the majority Contacts and points
of alloy compositions, some examples percents by weight:
Ag 72 - Cu 7.5
Ag 75 - Cu 24.5-Ni 0.5
Ag 97.5 - CdO 2.5
Ag 95 - CdO 5
Ag 90 - CdO 10
Ag 86.7 - CdO 13
Ag 85 - CdO 15
Ag 77 - Cd-O 22.6 - Ni 0.4
Ag 86.8 - Cd-O 5.5 - Ni 0.2 - Cu 7.5
Ag 95 - Ni 0.5
Ag 90 - Ni 10
Ag 85 - Ni 15
Ag 70 - Ni 30
Ag 60 - Ni 40
Ag 40 - Ni 60
Ag 99.75 - C 0.25
Ag 99.5 - C 0.5
Ag 99 - C 1.0
Ag 90 - C 10
Ag 88 - C 2.0 - Ni 10
Ag 90 - Fe 10
Fe 50 - Cu 25 - Ag 25
Ag 99.34 -MgO 0.41 - Ni 0.25
Ag 99.55 - Mg-O 0.25 - Ni 0.20
Ag 97 - Pt 3.0
Ag 90 - Pd 10
Ag 97 - Pd 3
Ag 99 - Pd 1
Ag90 - Au 10
Ag-Cu-Cd-Au
Some of the tungsten compositions:
Ag 27.5 - W 72.5
Ag 35 - W 65
Ag 49 - W 51
Ag 50 - W 50
Ag 46 W 53 - C 1.0
Ag 48 - W 51.75 - C 0.25
Ag 90 - W 10
Ag 65 - WC 35
Ag 50 - WC 50
Ag 40 - WC 60
Ag 40 - Mo 60
Ag 50 - Mo 50
Just a few of the gold or PGM types:
Pt-Rh 10
Pt-Ir 10
Pd-Ag 40
Au 99.99
Au-Ni 8
Au-Ag 15 Ni 10
There are spring materials made from copper, stainless steel, beryllium, bronze, and Kovar.
We can also have bi-metal alloys which deform under heat or current...
Bus bars can be made from other metals like copper or brass, stainless steels or other iron compounds...
Brazing alloys can have barium, cadmium, phosphates, chromium, lithium, and well as others...
Gold flashed silver, gold overlay base metals, silver nickel, silver cadmium oxide, silver tin indium, silver copper nickel, gold silver nickel, gold silver nickel palladium tungsten.
Some of the metals to watch for, Au, Pt, Pd, Rh, Ir, In, Os, Ag, Ni, Cu, Fe, Co, Cd, Mo, Sn, Pb, A, Hg, Mg, W, C, Zn, and oxides of several of these metals.
Silver is usually predominant.
if contacts were Russian, I would surely check for platinum group metals.
Tungsten is very resistive to acids, silver in HCl passivates, the high oxidizer can help to react with the tungsten, and the silver crust can be broken loose with vigorous stirring and knocking it around with a glass stir rod, if this is tungsten and silver it will not be fast or easy.
Tungsten (W) usually used in high current type, (waffle back), high melting point 3380 deg C, this can make melting difficult, not easily dissolved, hot HCl with concentrated H2O2 will attack.
Tungsten silver contacts, in a (50%: 50%) solution of 70% HNO3: H2O, heated can dissolve the silver out, leaving a porous shell of tungsten, that can be broken or crushed, when silver is removed,
The metals or alloys and combinations of metals, used are usually dependent on the purpose and use of the contact points (relay, breaker, switch, etcetera), the voltage, current, environments, inductance or capacitance in circuit, Arcing, welding, oxidation, pitting, inrush current, contact bouncing, whether AC or DC application...
Well, let's just say there are many factors that come into play when a contact point is used in electronics or electrical applications, and these little buttons of metals are in almost all electronic and electrical devices.
http://goldrefiningforum.com/~goldrefi/ ... 58&t=16364
Sometimes you can get datasheets for specifications with a search, of the relay or other switching devices there are some good posts listing metal used in switch's and breakers, allot of these contain mostly silver, I can not tell you what the Westinghouse or other brands of breaker’s, or switch points you have contains, but my guess is mostly silver, and that is the way I feel you should purchase them as silver, and also these can be a cost you in time and reagents so figure that also. Switches can contain gold or gold plating, but that is usually for low current and high reliability in switching like for digital electronics, large current devices will usually have tungsten.
Well, let's just say there are many factors that come into play when a contact point is used in electronics or electrical applications, and these little buttons of metals are in almost all electronic and electrical devices.
Melting contacts can produce deadly fumes cadmium and zinc as well as other volatile metal toxic fumes and floating oxidized particles of the metals easily breathed into the lungs.
http://www.google.com/search?hl=en&as_q ... s_occt=any
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=16869&p=170601&hilit=Group1%3A+Ag+Mo%2C+Ag+Cu#p170601
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=20969&p=215987&hilit=Group1%3A+Ag+Mo%2C+Ag+Cu#p215987
