Hi-Nicalon/BN/a-Si,N, ceramic-matrix composites not excluded that the processing REFERENCES route of the composite could also have an undesirable 1. Lamicq, P. and Boury, D, Ceramic matrix composite effect owing mainly to the diffusion of some elements parts design. In Proceedings of AGArD Workshop on such as aluminum. which could come from the tructural sintering additives. However, the composite showed Composites, Antalya, Turkey, 21-22 April 1993, pp. 12-1 extensive non-linear behavior, thus demonstrating that to12-12. he load transfer at the fiber/matrix interface is 2. Nakano. K. Kume, S, Sasaki d Saka, H Microstructure and mechanical properties of Hi-Nicalon acceptable fibers reinforced silicon nitride composite, Ceram. Eng One possible way to overcome the sensitivity of Hi Sci. Proc., in press Nicalon fibers to the Bn coating process is to replace 3. Ichikawa, T, Recent developments of the Sic fiber BCI by BF3 in reaction (11), the latter requiring a Nicalon and its composites, including properties of the lower temperature range(close to 1200C) C fiber Hi-Nicalon for ultra high temperature. Compos. Sci. TechnoL., 1994, 51, 135-144 Instrumented micro-indentation tests perforned on 4. Drissi-HabtL, M, Damage development and modt the matrix and fibers in the composite are very reduction in a unidirectional SiC-MAS L composite suitable and could provide an accurate estimate of the aterial tested under uniaxial tensile loading. Scripta mechanical properties of the composite. These pieces Metall.Maer,i995,33,967-973 of information could be helpful in evaluating the 5. Puttock, M.J. and Thwaite, E. G. Elastic compression of spheres and cylinders at point and line contact. Internal effects of the sintering process on the composite Report, CSIRO, Melbourne, 1969 constituents. In addition, only small samples are 6. Sneddon, L The relation between load and required and, at a laboratory scale, this is not a penetration in the axisymetric Boussinesq problem. Int negligible argument J. Eng, Sci,1965,1,47-52 7. Parlier, M, Passilly, B, and Sudre, O csented at AGARD Workshop on Introduction mics into Aerospace Structural Composites, Turkey, ACKNOWLEDGEMIENT 21-22 April 1993. AGARD Report 795, November 199 5-1to5-8. The authors wish to thank Dr miki from the national 8. Moore,A w, Facilities for continuous Cvd coating of Industrial Research Institute of Nagoya for his ceramIc fibers. In Materials Research Society Symposium ssistance in manipulating the atomic force Proceedings, VoL, 250. Materials Research Society, Pittsburg, Pennsylvania, 1992. microscope. 9. Matsuda. T, J Mater. Sci., 1989, 24, 2353Hi-Nicalon/BN/cy-Si,N, ceramic-matrix composites 1489 Nevertheless, it is not excluded that the processing route of the composite could also have an undesirable effect owing mainly to the diffusion of some elements such as aluminum, which could come from the sintering additives. However, the composite showed extensive non-linear behavior, thus demonstrating that the load transfer at the fiber/matrix interface is acceptable. One possible way to overcome the sensitivity of Hi￾Nicalon fibers to the BN coating process is to replace BC13 by BF3 in reaction (ll), the latter requiring a lower temperature range (close to 1200°C). Instrumented micro-indentation tests performed on the matrix and fibers in the composite are very suitable and could provide an accurate estimate of the mechanical properties of the composite. These pieces of information could be helpful in evaluating the effects of the sintering process on the composite constituents. In addition, only small samples are required and, at a laboratory scale, this is not a negligible argument. ACKNOWLEDGEMENT The authors wish to thank Dr Miki from the National Industrial Research Institute of Nagoya for his assistance in manipulating the atomic force microscope. REFERENCES 1. 2. 3. 4. 5. 6. Lamicq, P. and Boury, D., Ceramic matrix composite parts design. In Proceedings of AGARD Workshop on Introduction of Ceramics into Aerospace Structural Composites, Antalya, Turkey, 21-22 April 1993, pp. 12-1 to 12-12. Nakano, K., Kume, S., Sasakai, H. and Saka, H., Microstructure and mechanical properties of Hi-Nicalon fibers reinforced silicon nitride composite. Ceram. Eng. Sci. Proc., in press. lchikawa, T., Recent developments of the SIC fiber Nicalon and its composites, including properties of the SIC fiber Hi-Nicalon for ultra high temperature. Compos. Sci. Technol., 1994,51,135-144. Drissi-Habti, M., Damage development and moduli reduction in a unidirectional SIC-MASL composite material tested under uniaxial tensile loading. Scripta Metall. Mater., 1995, 33,967-973. Puttock, M. J. and Thwaite, E. G., Elastic compression of spheres and cylinders at point and line contact. Internal Report. CSIRO, Melbourne, 1969. Sneddon, L. N., The relation between load and penetration in the axisymetric Boussinesq problem. Int. 1. Eng. Sci., 1965, 1,47-52. Parlier, M., Passilly, B. and Sudre, O., paper presented at AGARD Workshop on Introduction of Ceramics into Aerospace Structural Composites, Antalya, Turkey, 21-22 April 1993. AGARD Report 795, November 1993, pp. 5-l to 5-8. Moore, A. W., Facilities for continuous CVD coating of ceramic fibers. In Materials Research Society Symposium Proceedings, Vol. 250. Materials Research Society, Pittsburg, Pennsylvania, 1992. Matsuda, T., J. Mater Sci., 1989,24,2353