I can't seem to find any reference to dragonbone armour. However, there are a few examples weapons in the series that contain dragonbone.
A dragonbone bow is given to Daenerys as a "bride's gift".
The khal's bloodriders offered her the traditional three weapons, and splendid weapons they were. Haggo gave her a great leather whip with a silver handle, Cohollo a magnificent arakh chased in gold, and Qotho a double-curved dragonbone bow taller than she was.
A Game of Thrones, Daenerys II
Later on she gives the same bow to Aggo.
"Aggo," Dany called, paying no heed to Jhogo's words. If I look back I am lost. "To you I give the dragonbone bow that was my bride gift." It was double-curved, shiny black and exquisite, taller than she was. "I name you ko, and ask your oath, that you should live and die as blood of my blood, riding at my side to keep me safe from harm."
A Game of Thrones, Daenerys X
Note that there is also reference to other dragonbone bows being used by the Dothraki in a book that Tyrion reads.
He found a comfortable spot just beyond the noise of the camp, beside a swift-running stream with waters clear and cold as ice. A grotesquely ancient oak provided shelter from the biting wind. Tyrion curled up in his fur with his back against the trunk, took a sip of the wine, and began to read about the properties of dragonbone. Dragonbone is black because of its high iron content, the book told him. It is strong as steel, yet lighter and far more flexible, and of course utterly impervious to fire. Dragonbone bows are greatly prized by the Dothraki, and small wonder. An archer so armed can outrange any wooden bow.
A Game of Thrones, Tyrion II
Another weapon is the Valyrian steel dagger that was used by the catspaw in the attempt on Bran's life.
"We found the knife still in the villain's grasp. It seemed to me that it was altogether too fine a weapon for such a man, so I looked at it long and hard. The blade is Valyrian steel, the hilt dragonbone. A weapon like that has no business being in the hands of such as him. Someone gave it to him."
A Game of Thrones, Catelyn III
We also see a whip with a dragonbone handle.
Dany handed the slaver the end of Drogon's chain. In return he presented her with the whip. The handle was black dragonbone, elaborately carved and inlaid with gold. Nine long thin leather lashes trailed from it, each one tipped by a gilded claw. The gold pommel was a woman's head, with pointed ivory teeth. "The harpy's fingers," Kraznys named the scourge.
A Storm of Swords, Daenerys III
Although not armour or a weapon we do have reference to dragonbone being used for jewellery.
"She's too skinny," Viserys said. His hair, the same silver-blond as hers, had been pulled back tightly behind his head and fastened with a dragonbone brooch. It was a severe look that emphasized the hard, gaunt lines of his face. He rested his hand on the hilt of the sword that Illyrio had lent him, and said, "Are you sure that Khal Drogo likes his women this young?"
A Game of Thrones, Daenerys I