Graves with black cleaver?

I was just wondering peoples opinion on this item for Graves. I used it my last game with him to burst down heavy tanks with the added CDR and armor pen. I used it with Lord Dominik's Regards and just shredded through super heavy tanks. Mainly a pretty big Nasus late game who was destroying my whole team. After cleaver though I could 1v1 him even with his frozen heart and armor/health items, not to mention his hard hitting ass stacked Q. I would basically Q, double auto, E double auto, Ult, Q, and so on.