J Rebelo Kornmeier et al. Materials Characterization 58(2007)922-92 neutrons that pass through the sample are recorded by a nitrogen cooled CCD-camera system. The basic princi- ple of the detector is the combination of a CCD-camera SiC matrix with a neutron-sensitive scintillator screen ( Li6 or gd as neutron absorber). The light from the screen is reflected to the camera by a mirror and focused on the CCD-chip by a special lens [6] The nozzle was incrementally rotated between 0- 180C using 600 steps whilst irradiating the nozzle for Fibre 30 s for each angle. The resolution obtained was about 300 In Fig. 2 intensity distributions are shown for cross sections parallel (a)and perpendicular, (b) and(c), to the nozzle axis In Fig. 2 the dark grey colour represents the Fig. 4. Three-dimensional view of an exemplary sample of ceramic material which has the highest absorption, i. e. where the composite(C/SiC) fibre concentration is higher. It can be clearly seen where the nozzle was reinforced. the fibre concentration has, the more it attenuates X-rays. Neutrons, on the being higher in the interior side of the throat region. other hand. interact with the atomic nuclei but show no obvious regularity across the periodic table of elements. 2. 3. Neutron tomography of the solder connection Interaction strongly depends on the inner structure of the atomic nuclei, meaning that even isotopes of the same Neutron tomography was also applied to the nozzle element may often provide very different levels of shown in Fig. 3d)in order to verify the solder distribution in contrast in the projection. The high degree of neutron the joint section between the nozzle and the metal scattering caused by hydrogen and the penetration component using thermal neutrons. The different absorp- capacity of neutrons for most metals are of particular tions coefficients of the materials enable their identification industrial significance [5]. and, hence, a representation of their distribution over the components volume. The results are presented in Fig. 3 2. 2. Neutron tomography of the nozzle showing in a)a cross section of the C/Sic nozzle connected with the metal ring, the dark grey colour representing the The neutron tomographies were carried out at the solder material. Such cross sectional views can be obtained instrument NEUTRA at the Paul Scherrer Institut(PSD) at any axial position and angle. Three-dimensional in Switzerland using thermal neutrons with an energy representations of isolated solder are also possible, see range between 2 meV and 100 meV. The thermal Fig 3b)and c). It can be seen that almost all cavities were Fig. 5. (a)Temperature tested nozzle;(b)residual stress measurement directions at throat region.(b) Residual stress measurement apparatus at HMIhas, the more it attenuates X-rays. Neutrons, on the other hand, interact with the atomic nuclei, but show no obvious regularity across the periodic table of elements. Interaction strongly depends on the inner structure of the atomic nuclei, meaning that even isotopes of the same element may often provide very different levels of contrast in the projection. The high degree of neutron scattering caused by hydrogen and the penetration capacity of neutrons for most metals are of particular industrial significance [5]. 2.2. Neutron tomography of the nozzle The neutron tomographies were carried out at the instrument NEUTRA at the Paul Scherrer Institut (PSI) in Switzerland using thermal neutrons with an energy range between 2 meV and 100 meV. The thermal neutrons that pass through the sample are recorded by a nitrogen cooled CCD-camera system. The basic princi￾ple of the detector is the combination of a CCD-camera with a neutron-sensitive scintillator screen (Li6 or Gd as neutron absorber). The light from the screen is reflected to the camera by a mirror and focused on the CCD-chip by a special lens [6]. The nozzle was incrementally rotated between 0– 180 °C using 600 steps whilst irradiating the nozzle for 30 s for each angle. The resolution obtained was about 300 μm. In Fig. 2 intensity distributions are shown for cross sections parallel (a) and perpendicular, (b) and (c), to the nozzle axis. In Fig. 2 the dark grey colour represents the material which has the highest absorption, i.e. where the fibre concentration is higher. It can be clearly seen where the nozzle was reinforced, the fibre concentration being higher in the interior side of the throat region. 2.3. Neutron tomography of the solder connection Neutron tomography was also applied to the nozzle shown in Fig. 3d) in order to verify the solder distribution in the joint section between the nozzle and the metal component using thermal neutrons. The different absorp￾tions coefficients of the materials enable their identification and, hence, a representation of their distribution over the component's volume. The results are presented in Fig. 3 showing in a) a cross section of the C/SiC nozzle connected with the metal ring, the dark grey colour representing the solder material. Such cross sectional views can be obtained at any axial position and angle. Three-dimensional representations of isolated solder are also possible, see Fig. 3b) and c). It can be seen that almost all cavities were Fig. 5. (a) Temperature tested nozzle; (b) residual stress measurement directions at throat region. (b) Residual stress measurement apparatus at HMI, Berlin. Fig. 4. Three-dimensional view of an exemplary sample of ceramic composite (C/SiC). J. Rebelo Kornmeier et al. / Materials Characterization 58 (2007) 922–927 925