A Study of Room-temperature-nitriding Process of Pure Titanium Using Scanning Cyclic Press under Controlled Atmosphere

Abstract

A new surface modification technique, scanning cyclic press (SCP), was applied to commercially pure titanium (CP-Ti) in a nitrogen atmosphere at room temperature. During the SCP process, a vibrating indenter reciprocally scanned the specimen’s surface to apply cyclic low compressive load. In this study, a possibility of a room-temperature-nitriding technique using SCP was investigated. Before and after SCP, the surface and the cross-section of the specimens were observed using a laser microscope and scanning ion microscope (SIM), respectively. Then, elemental and composition analyses were conducted by using EPMA and XRD. As a result, a pale golden color, which is known as a characteristic of titanium nitride coating, appeared at the surface of SCP-treated specimen. The SIM observation of the cross-section showed that a nanocrystalline structure was created in the surface layer, and the nitrogen element was detected in the same layer. The XRD analysis showed a strong possibility to form titanium nitride at the surface of SCP-treated specimen. These results suggested that nitrogen element surrounding the specimen diffused into the microstructure beneath the surface and likely created titanium nitride during SCP even at room temperature.