precious alloys Flashcards
(20 cards)
what is an alloy
a material may of two or more chemical elements with one of them being metal
what do high noble alloys contain
at least 40% gold
what do noble metal alloys contain
at least 25% noble metal
what do base metal alloys contain
less than 25% noble metal
what is contained in amalgam
mercury, silver, tin, copper
what certificate is given to pt and put in pt notes - ensures the material is exactly what the pt is paying for e.g. gold if u want gold
IdentAlloy
how does gold affect the alloy
Malleable, lacks strength, minimal abrasiveness, tarnish resistant, corrosion resistant, ductile, high wear resistance
how does palladium affect the alloy
Whitens gold, raises melting point/elastic modulus/strength/hardness, lowers density of gold alloys
how does platinum affect the alloy
○ Increases melting range, hardness, strength and elastic modulus of gold alloys
Decreases thermal expansion coefficient of gold alloys
how does silver affect the alloy
Increase thermal expansion coefficient
how does zinc affect the alloy
Reduces porosity during casting procedures
type 1 vs type 4 dental casting gold alloy
Type 1 - more gold - low strength
type 4 - least gold - high strength
how does gold affect material hardness
Less gold = harder material
how does gold affect proportional limit
Less gold = lower proportional limit
how does gold affect strength
Less gold = lower strength
how does gold affect ductility
Less gold = higher ductility
how does gold affect corrosion resistance
Less gold = higher corrosion resistance
hardening heat treatments can be done on what types of dental casting gold alloys
type 3 and 4 only as it doesn’t work on gold
Nobility of gold can be indicated by what 2 things
Carats (24 highest part) and fineness (1000 highest part)
If u extract a tooth with gold in it what must u do?
remove the gold and offer it to the pt
