Fact: The armor most commonly associated with knights in popular culture is called plate armor.
Fact: There is also a type of armor called mail or chain mail.
Fact: They are not and can not be the same thing.
(There were mixed suits of armor, but the two are fundamentally different things. Plate armor was much heavier and more effective at protection-there are stories of armored men falling off their horses and getting mobbed by poorly armed peasants, and being attacked for hours at a time, but still escaping unhurt-while mail allowed much greater flexibility. Mixed suits often protected inflexible areas with heavier armor while covering joints with mail for flexibility.
Yes, I am a huge historical weapons nerd, why do you ask?)
That doesn't stop people from calling a "famous" suit of plate armor the "Black Mail" in this Iron Ace story (from Air Fighters v. 2, #8), though.
Oh, yes, and they put a remote control robot inside it, and supposedly this ancient suit of armor "cannot be destroyed because of the way that it is constructed!"
(SPOILER: This was, shall we say, an exaggeration.)
Gotta love those Golden Age comic book writers.