| Research Abstract |
Some cermets; TaC, TaC, ZrC, ZrN, TiC, TiN and TiィイD22ィエD2AIN have been fabricated successfully from metals; Ta, Zr, Ti and TiAl, respectively, by means of the reactive plasma processing developed originally. Each cermet was formed at a sub-surface of base metal as a thick layer of carbide or nitride. The decomposition temperature of TaC, ZrC and TiC, produced by sintering were reported to reach 4000, 3550 and 3300℃, respectively. The plasma processing was done at high temperature over 1000℃. Thicknesses of cermets were increased with the processing-temperature and the processing-time. As the results of the preliminary experiment, the maximum Vicker's hardness and thickness of cermets; TaC, ZrC and TiィイD22ィエD2AIN were 3000Hv/100μm for 5h, 1300Hv/100μm for 5h and 3500Hv/24μm for 3h [Hv;kg・mmィイD12ィエD1], respectively.
The characteristic features of processed cermets were on the points, 1) Cermets were produced at the sub-surface of base metals by means of transformation of base metals-themselves with an aid of carbon or nitrogen diffused from the surface facing the processing plasma, 2) The concentration profile of carbon- or nitrogen-compounds degraded gradually in the modified layer and the interface with the distance from the surface. The cermet layers must have the properties of functionally graded materials on hardness, thermal conductivity and the abrasion resistance of modified layer.
Additionally, the new processing with 20MeV-electron beam was performed before the plasma processing for increasing the thickness of modified layer at the lower processing temperature. The thickness of TaC-cermet layer carbonized at 1300℃ after the irradition to a fluence of 3×10ィイD115ィエD1 e・cmィイD1-2ィエD1 increased by about four times that of non-irradiation at 1000℃.
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