HS2440 Week 8 Asyn_Lead and lead alloy corrosion (copy) Flashcards
lead has two o______ states. they are…
(diagrams showing compounds which are stable and produced in pure and carbonated water)
two oxidation states; pb2+ (more common) and pb4+
lead oxide produces a protective surface layer, but occurs rarely because corrosion is influenced by co2 and organic acids, which impacts corrosion rate
in pure water lead corrodes, there is no protective layer
lead carbonate forms a protected layer.
diagram showing lead compounds formed in water with sulphides
better conditions for survival
c_____ pollutants are in the museum environment and atmosphere, and cause lead corrosion.
what are some sources of organic acids, and examples
Carbonyl (carbon double bonded to oxygen)
Image showing how lead corrodes due to organic acids, how are corrosion products formed?
- growth of basic carbonate on surface
- acid attacks surface, producing soluble lead acetate, which is an electrolyte, but its more complicated in reality
- voluminous corrosion products
what are come of the range of compounds formed during complex reactions with lead and pollutants (organic acids)
- high occurrence of lead hydroxide
- mostly 2+ ions
table showing copper and lead at different humidities, reacting with organic acid pollutants
what are the specific decay routes fro a baroque organ
- lead and wood
- damp unheated, temperature changes,
- aecetic acids, condensation causing corrosion of lead
why do specific compounds occur?
pourbaix diagram for tin in water
dotted line indicate expected regions and conditions, and stable compounds expected
tin burial and atmosphere; characteristics of corrosion products
porbaix diagram for tin, in an archaeological burial environment, with the presence of chlorides
Pewter; a mix of…
how does pewter corrode because of these components
corrosion form for pewter
