Elevated Temperature Ion Implantation: A New Direction for Surface Engineering

Abstract

The advantages of ion implantation as a method for surface treatment are substantial. Improvements in hardness, wear and corrosion resistance of many steels have been obtained through relatively short time exposure to a flux of interstitial ions such as carbon or nitrogen. However, the depth of the implanted layer is extremely small after conventional implantation, generally in the range of 1000Å or less. For many applications, such as abrasive and corrosion wear, these layers are of insufficient thickness to provide long term improvement.

In order to achieve increased layer thickness, ion implantation with nitrogen has been carried out at 550°C. Using the Plasma Source Ion Implantation (PSII) device, specimens of several different alloys were implanted at elevated temperatures, using the ion flux as the heating source.

A number of commercial alloys were investigated to study the effectiveness of elevated temperature nitrogen ion PSII implantation in creating engineered surfaces having superior properties. These included several alloy steels and several nickel-based superalloys. Detailed evaluation of metallography, hardness and wear have been conducted. Selected alloys were examined using transmission electron microscopy and scanning auger microscopy. Support for this research was provided by NSF Grant DMC-8712461 and ECS-8314488, and by DAAL03-89-K-0048.