Effect of Ion-Implantation on the Microstructure of Si3N4 Based Ceramics

Si3N4 based ceramics that made by hot isostatic press, were implanted at room temperature with N+ - and C+ - ions with energy of 500 keV and 2 MeV, respectively. The specimens were irradiated at a fluence of 1017 ion/cm2. The microstructure changes after ionimplantation in the surface layer were investigated by transmission electron microscopy (TEM). The effect of ion-implantation on the tribological properties was also studied. After N+ and C+ ionimplantation an amorphous layer near to the surface has been formed which was observed by electron diffraction measurement. The wear tests were performed by means of a ball-on-disk configuration using commercially available Si3N4 ball. The friction coefficient was measured online, the wear coefficient was determined on the base of the wear scar sizes. The specific wear rate was reduced by N+-implantation and the coefficient of friction was lower in the initial stage in both cases.

FUNDAMENTAL ASPECTS OF THE IONIZED CLUSTER-BEAM DEPOSITION PROCESS

The electron diffraction measurement of Sb beams ejected by adiabatic expansion from a nozzle source showed that a considerable amount of clusters with a highly disordered atomic arrangement was produced. The cluster size was found to be larger than a few tens of atoms per cluster, though the exact size could not be determined. It was reported that after impact of clusters ejected from the nozzle source, cluster islands were formed on a substrate surface, and that the film formation started by direct deposition of clusters as the rapid nucleation of cluster islands. These results supported the notion that large atomic clusters existed in the beam.