Investigation of ion implanted electroplated chromium from a trivalent bath

The objective of this work is to compare chromium electroplated from a hexavalent bath, Cr(+6) with a more environmentally friendly process; nitrogen;plasma source ion implantation of chromium from a trivalent bath Cr(+3) which transforms it into a material that is harder than as-deposited Cr(+3) with equal or better wear resistance properties. As-deposited, the hardness of a Cr(+6) layer is higher (1200-1500 Knoop) than that of an as-deposited Cr(+3) layer (950-1100 Knoop). Nitrogen-ion implantation at 120 kV to a dose higher than 3 x 10(17) N/cm(2) increases the hardness of-the Cr(+3) to 2300 Knoop. Wear resistance measurements show that under the same wear conditions a M-ion-implanted Cr(+3) layer has about twice the wear resistance than the as-deposited Cr(+3) and Cr(+6) layer. Specifically, the width of the wear groove in a pin-on-disk test of an-implanted Cr(+3) plated layer is 60 mu m fdr a 100 g load while for an as-deposited Cr(+6) under the same load, the groove width is 114 mu m. In this report we also demonstrate that,nitrogen ion implantation into trivalent-deposited Cr(+3) achieves the same chromium nitride phases and hardness as nitrogen-implanted Cr(+6). (C) 1999 American Vacuum Society. [S0734-211X(99)02102-2].