Wear resistance of ion-implanted, chemically vapor-deposited nickel die inserts

High precision dies can be fabricated to a near-net shape by nickel vapor forming; however, die wear severely limits the precision of the product when these nickel dies are used in the molding of glass-filled epoxy parts. Ion implantation of N + into die surfaces improved the wear resistance of the dies and decreased the friction coefficient, as determined by pin-on-disc testing; the pins were made from glass-filled epoxy. Transmission electron microscopy showed that the N + implantation treatment transformed the surfaces of the dies to Ni 3N; the improved wear resistance and the decrease in the friction coefficient are attributed to this hard interstitial compound. In contrast, the dual-ion implantation of Ti + and C + into die surfaces produced amorphous surface layers but did not modify either the friction coefficient or the wear resistance significantly. Friction and wear results are shown to be influenced by sliding velocity. The wear process is a combination of adhesion and abrasion.