Structure and properties of the surface layer of «Ti/SiC-ceramic» system irradiated by low-energy pulsed electron beam

Abstract

The results of the investigation of evolution structural phase states of the surface layer «film (Ti)/substrate (SiC-ceramics)» system subjected to processing with an intense pulsed electron beam are presented (Ti film 0.5 μm thick was deposited on the surface SiC ceramic). Samples of SiC ceramics obtained by SPS-sintering were used. Irradiation with an intense pulsed electron beam of submillisecond duration was carried out at the «SOLO» device under the condition: energy density of the electron beam of 15 J/cm2, pulse duration of 200 μs, quantity of pulses – 20 and 30. The X-ray diffraction analysis of the treated electron beam «Ti/SiC» system showed that under the specified irradiation regime the phase composition formed in the surface layer and the volume fraction of the phases depend on the quantity of irradiation pulses. At 20 pulses, following phase composition of the surface layer was formed: SiC – 18.5 %, TiC – 36.6 %, Ti5Si3 – 44.9 %; at 30 pulses, a phase relationship: SiC – 81.6 %, TiC – 12.7 %, Si – 0.5 %, C – 5.2 %. Scanning and transmission electron microscopy revealed, that irrespective of the quantity of pulses of the electron beam, takes place the formation of a surface layer with a globular structure, formed as a result of melting of the titanium film, which contains a droplet fraction. The particles of the drop fraction had a submicro-nanocrystalline structure and were enriched mainly by titanium, silicon and carbon atoms. It was established that electron beam treatment with 30 pulses leads to formation of round-shaped regions on the surface of irradiation, the microhardness of which varies from 55 GPa to 96 GPa, which is several times the microhardness of the initial SiC ceramic (36 GPa). It was suggested that these regions were formed as a result of electron beam treatment of the surface layer, which contains a drop fraction.