SCANNING MICROANALYSIS OF SIC-SI3N4 MATERIAL BY PROTON NON-RUTHERFORDELASTIC BACKSCATTERING

By the use of a 3 MeV proton microbeam we succeeded in studying SiC-Si 3N4 composite ceramics quantitatively. Proton backscattering in the Me V non-Rutherford energy region is more sensitive to detecting low-Z el ements, such as C, N and 0, than other ion beam methods when a heavier element is present in the matrix. The microbeam analysis was performe d by scanning an inclined cross section of the sample for improving th e depth resolution. The results confirm that a SiC-Si3N4 composite lay er can be formed on the presintered SiC substrate under the condition of an isostatic pressure of 200 MPa in N2 atmosphere at 1850-degrees-C . About 60% of the SiC was transformed into Si3N4 in a surface layer o f over 10 mum, when the reaction lasted one hour. The uncertainty in t he concentration is not larger than +/- 10% in directions parallel to the target surface. The maps of nitrogen and carbon, in three dimensio ns, are also given in the interface region.