April 2007 Sic-Based Fibers and Low Oxygen Conten 1147 Table I. Properties of Sic Fibers Investigated in the Present Study ippon Carbon Co., Japan Ube Industries Ltd, Japan Hi-Nicalon Hi-Nicalon S 43(2) Batch no 225103 320203 M-010071 Diameter (um) Density(g/cm 3.0 3.l Tensile strength(GPa) 2.516 Tensile modulus(GPa) Grains size(nm) X-ray diffraction 5-10 60-70 60-70 Transmission electron microscopy 50400 Chemical composition(wt%/at. % 621/41.3 84/48.l 666/46.0(edge) 69.1/49(edge) 0.3/395(core) 66.1/45.6(core) 37.7/58.5 0.5/50.7(edge) 39.2/60.l(core) 33.5/54.l(core) 1. 16(edg 1.03(edge) .52(c 1.19(core) Fig 1. Schematic diagram of the high-temperature fiber-testing apparatus. circulating through the fiber, under secondary vacuum(residual The fiber was first kept stress-free at the test temperature for pressure <*Pa). In such an environment, active oxidation is 30 min. Then, the stress was applied. This loading step took less infinitively slow. The temperature of the fiber was measured than 10 s. The diameter of each fiber was measured in situ using using a bichromatic pyrometer (IrCON. Niles, IL). The tem- a laser mounted on the testing apparatus. It is given by the av- perature profiles showed that the temperature is uniform over erage of several measurements along the gauge length t To en- more than 95% of the gauge length. Furthermore, it appeared sure a good reproducibility of the results, only those specimens hat grips remained at a temperature close to room temperature with quite uniform diameters along the gauge were tested For during the tests(<50.C). Thus, the loading frame compliance these specimens, the diameters measured along the fiber differed was not affected during the tests fiber deformations can be from the average by <3% derived from grip displacement. Loading frame compliance was Fiber deformations were derived from grip displac taken to be equal to that estimated at room temperature. Com- Data were corrected to account for deformation of the putations of temperature distributions for various thermal con- frame. The loading frame compliance was estimated us ductivities showed that the temperature gradient from the core to the surface of the fiber is<2°at1000°C13 'The cross sections of fibers are circular. The diameter is variable along the gaugecirculating through the fiber, under secondary vacuum (residual pressure B10
4 Pa). In such an environment, active oxidation is infinitively slow.14 The temperature of the fiber was measured using a bichromatic pyrometer (IRCON, Niles, IL). The tem￾perature profiles showed that the temperature is uniform over more than 95% of the gauge length.13 Furthermore, it appeared that grips remained at a temperature close to room temperature during the tests (o501C). Thus, the loading frame compliance was not affected during the tests. Fiber deformations can be derived from grip displacement. Loading frame compliance was taken to be equal to that estimated at room temperature. Com￾putations of temperature distributions for various thermal con￾ductivities showed that the temperature gradient from the core to the surface of the fiber is o21C at 10001C.13 The fiber was first kept stress-free at the test temperature for 30 min. Then, the stress was applied. This loading step took less than 10 s. The diameter of each fiber was measured in situ using a laser mounted on the testing apparatus. It is given by the av￾erage of several measurements along the gauge length.z To en￾sure a good reproducibility of the results, only those specimens with quite uniform diameters along the gauge were tested. For these specimens, the diameters measured along the fiber differed from the average by o3%. Fiber deformations were derived from grip displacement. Data were corrected to account for deformation of the loading frame. The loading frame compliance was estimated using the Quartz chamber x y Camera z Mirror Light Laser y z Mirror Mirror Vacuum captor displacement table Pyrometer Fig. 1. Schematic diagram of the high-temperature fiber-testing apparatus. Table I. Properties of SiC Fibers Investigated in the Present Study Suppliers Nippon Carbon Co., Japan Ube Industries Ltd., Japan Type of fiber Hi-Nicalon Hi-Nicalon S Tyranno SA3 (1) Tyranno SA3 (2) Batch no. 225103 320203 M-0110071 M-0304041 Diameter (mm) 1416 1316 7.5 7.2 Density (g/cm3 ) 2.7416 3.016 3.0 3.1 Tensile strength (GPa) 2.816 2.516 2.816 2.8 Tensile modulus (GPa) 290 375 325 380 Grains size (nm) X-ray diffraction 5–10 20 60–70 60–70 Transmission electron microscopy 5–10 10–50 50–400 50–400 Chemical composition (wt%/at.%) Si 62.1/41.3 68.4/48.1 66.6/46.0 (edge) 69.1/49 (edge) 60.3/39.5 (core) 66.1/45.6 (core) C 37.7/58.5 31.3/51.5 33/53.6 (edge) 30.5/50.7 (edge) 39.2/60.1 (core) 33.5/54.1 (core) O 0.2/0.2 0.3/0.3 0.2/0.2 0.1/0.1 Al — — 0.3/0.2 0.3/0.2 C/Si (at.%) 1.41 1.07 1.16 (edge) 1.03 (edge) 1.52 (core) 1.19 (core) z The cross sections of fibers are circular. The diameter is variable along the gauge. April 2007 SiC-Based Fibers and Low Oxygen Content 1147