Abstract Worldwide, high performance research and material test reactors are aiming to convert th... more Abstract Worldwide, high performance research and material test reactors are aiming to convert their fuel from high enriched uranium towards low enriched ones. High density U–Mo/Al based nuclear fuels are considered as a promising candidate for this conversion. However, during in-pile test irradiations, the formation of an interdiffusion layer (IDL) between the U–Mo and the Al matrix is observed, caused by irradiation enhanced U–Al interdiffusion processes. This IDL accumulates fission gases at the IDL/matrix interfaces. Together, these two effects strongly reduce the performance of this new fuel type. Recently, the out-of-pile technique of heavy ion irradiation ( 127 I) on U–Mo/Al layer systems proved to be an alternative to time-consuming in-pile test irradiations for certain fuel behaviour aspects. Here we present SIMS and SEM investigations of non-conventional 82 Kr implantation into previously heavy ion irradiated U–Mo/Al layer systems. It is shown that Kr accumulates inside μm large porosities at the IDL/matrix interfaces. This critical accumulation of μm-sized large gas bubbles is directly related to the presence of the irradiation induced IDL. Without IDL no critical accumulation of fission gas bubbles occurs.
ABSTRACT Properties of textile-laminated phenolic composition cages were studied by ToF-SIMS: (i)... more ABSTRACT Properties of textile-laminated phenolic composition cages were studied by ToF-SIMS: (i) by monitoring the di-octyl-sebacate (DOS) content of the lubricant film within the elastohydrodynamic (EHD) contact region of the inner and outer rings of tested high-speed rolling element bearings, and (ii) by the investigation of boundary layers of cages in the region of the cage–ball-contact. Portions of the DOS amount stored in the cage by the bearing conservation process are released vs. the operation time via the cage surfaces into the EHD contact regions.It was revealed that the amount of the diester DOS separated from the cage into lubricating film of the raceway, is influenced by the lubricant additive formulations used in the tribological tests via their attributes concerning the acting tribological system processes like wear, boundary layer formation, adsorption, etc. ToF-SIMS research [1,2] of both the lubricant surface and the boundary layer in the EHD contact region showed that the primary antioxidants used as additives do not only act as oxidation inhibitors, but that they also do influence the wear processes of the counteracting bodies and the formation processes of boundary layers on rolling bearing steel SAE 52100.With the amounts of DOS, found in dependence on six different lubricant additive formulations A–F investigated, also an influence on the boundary layer formation processes is detected for the surface of the textile-laminated phenolic composition cage. ToF-SIMS imaging and depth profiling of cage boundary layers prove this dependence of the boundary layer formation process.The secondary ion (SI) intensities of DOS correspond with the lubricant dependence of the 56Fe+/C4H8+ ratios obtained from the used lubricant films in the EHD contact regions [1,3] as well as with the ratios 56Fe+/C4H8+ of the boundary layers in the raceways and of the cages [3]. Both the 56Fe+/C4H8+ ratios and the DOS intensity values show an indirect dependence to the lubricant service life of the lubricants A–F.
Standing Lamb waves in vibrating plates enable haptic interfaces. If the out‐of‐plane displacemen... more Standing Lamb waves in vibrating plates enable haptic interfaces. If the out‐of‐plane displacement of these waves exceeds 1 µm at frequencies above 25 kHz, a silent friction modulation can be created between a human finger and a vibrating plate. A fully transparent friction‐modulation haptic device based on a piezoelectric thin film is demonstrated. The antisymmetric Lamb mode induced at 73 kHz allows for a functional performance that fulfills all conditions for practical use. Out‐of‐plane displacement reaches 2.9 µm when 150 V unipolar voltage is applied. The average transmittance of the whole transducer reaches 75%. The key points of this technology are: 1) a thin HfO2 layer between lead zirconate titanate film and substrate that prevents chemical reaction between them; 2) the efficient integration of transparent indium tin oxide electrodes and solution‐derived piezoelectric lead zirconate titanate thin film onto optical‐grade fused silica; and 3) the use of a transparent insulating layer made of SU‐8 photoresist.
Abstract Only a few studies deals with the alteration of glass by water vapor. This study aims to... more Abstract Only a few studies deals with the alteration of glass by water vapor. This study aims to investigate the mechanisms and to determine the kinetics of alteration of potash-lime silicate glass typical of the Middle Ages. For that, model glass samples were exposed to different conditions (relative humidity -RH-, temperatures) for several durations. The water vapor used in experiments was enriched in deuterium (D) and oxygen-18 (18O). Results show that mechanisms are highly temperature-dependent. At 50 °C, the alteration is driven by interdiffusion, whereas at 20 °C, the alteration is mainly governed by hydration without significant ion exchange. Then, the isotopic profiles of H, D, 18O and 16O show that after sorption of water molecules at the glass surface, the diffusing species in the glass matrix are mainly H+ or D+. Concerning the hydration kinetics, they evolve exponentially with time in the first stages of the alteration. Moreover, at 50 °C, the hydration follows a linear trend below 83% RH and strongly increases for higher RH values.
Abstract Worldwide, high performance research and material test reactors are aiming to convert th... more Abstract Worldwide, high performance research and material test reactors are aiming to convert their fuel from high enriched uranium towards low enriched ones. High density U–Mo/Al based nuclear fuels are considered as a promising candidate for this conversion. However, during in-pile test irradiations, the formation of an interdiffusion layer (IDL) between the U–Mo and the Al matrix is observed, caused by irradiation enhanced U–Al interdiffusion processes. This IDL accumulates fission gases at the IDL/matrix interfaces. Together, these two effects strongly reduce the performance of this new fuel type. Recently, the out-of-pile technique of heavy ion irradiation ( 127 I) on U–Mo/Al layer systems proved to be an alternative to time-consuming in-pile test irradiations for certain fuel behaviour aspects. Here we present SIMS and SEM investigations of non-conventional 82 Kr implantation into previously heavy ion irradiated U–Mo/Al layer systems. It is shown that Kr accumulates inside μm large porosities at the IDL/matrix interfaces. This critical accumulation of μm-sized large gas bubbles is directly related to the presence of the irradiation induced IDL. Without IDL no critical accumulation of fission gas bubbles occurs.
ABSTRACT Properties of textile-laminated phenolic composition cages were studied by ToF-SIMS: (i)... more ABSTRACT Properties of textile-laminated phenolic composition cages were studied by ToF-SIMS: (i) by monitoring the di-octyl-sebacate (DOS) content of the lubricant film within the elastohydrodynamic (EHD) contact region of the inner and outer rings of tested high-speed rolling element bearings, and (ii) by the investigation of boundary layers of cages in the region of the cage–ball-contact. Portions of the DOS amount stored in the cage by the bearing conservation process are released vs. the operation time via the cage surfaces into the EHD contact regions.It was revealed that the amount of the diester DOS separated from the cage into lubricating film of the raceway, is influenced by the lubricant additive formulations used in the tribological tests via their attributes concerning the acting tribological system processes like wear, boundary layer formation, adsorption, etc. ToF-SIMS research [1,2] of both the lubricant surface and the boundary layer in the EHD contact region showed that the primary antioxidants used as additives do not only act as oxidation inhibitors, but that they also do influence the wear processes of the counteracting bodies and the formation processes of boundary layers on rolling bearing steel SAE 52100.With the amounts of DOS, found in dependence on six different lubricant additive formulations A–F investigated, also an influence on the boundary layer formation processes is detected for the surface of the textile-laminated phenolic composition cage. ToF-SIMS imaging and depth profiling of cage boundary layers prove this dependence of the boundary layer formation process.The secondary ion (SI) intensities of DOS correspond with the lubricant dependence of the 56Fe+/C4H8+ ratios obtained from the used lubricant films in the EHD contact regions [1,3] as well as with the ratios 56Fe+/C4H8+ of the boundary layers in the raceways and of the cages [3]. Both the 56Fe+/C4H8+ ratios and the DOS intensity values show an indirect dependence to the lubricant service life of the lubricants A–F.
Standing Lamb waves in vibrating plates enable haptic interfaces. If the out‐of‐plane displacemen... more Standing Lamb waves in vibrating plates enable haptic interfaces. If the out‐of‐plane displacement of these waves exceeds 1 µm at frequencies above 25 kHz, a silent friction modulation can be created between a human finger and a vibrating plate. A fully transparent friction‐modulation haptic device based on a piezoelectric thin film is demonstrated. The antisymmetric Lamb mode induced at 73 kHz allows for a functional performance that fulfills all conditions for practical use. Out‐of‐plane displacement reaches 2.9 µm when 150 V unipolar voltage is applied. The average transmittance of the whole transducer reaches 75%. The key points of this technology are: 1) a thin HfO2 layer between lead zirconate titanate film and substrate that prevents chemical reaction between them; 2) the efficient integration of transparent indium tin oxide electrodes and solution‐derived piezoelectric lead zirconate titanate thin film onto optical‐grade fused silica; and 3) the use of a transparent insulating layer made of SU‐8 photoresist.
Abstract Only a few studies deals with the alteration of glass by water vapor. This study aims to... more Abstract Only a few studies deals with the alteration of glass by water vapor. This study aims to investigate the mechanisms and to determine the kinetics of alteration of potash-lime silicate glass typical of the Middle Ages. For that, model glass samples were exposed to different conditions (relative humidity -RH-, temperatures) for several durations. The water vapor used in experiments was enriched in deuterium (D) and oxygen-18 (18O). Results show that mechanisms are highly temperature-dependent. At 50 °C, the alteration is driven by interdiffusion, whereas at 20 °C, the alteration is mainly governed by hydration without significant ion exchange. Then, the isotopic profiles of H, D, 18O and 16O show that after sorption of water molecules at the glass surface, the diffusing species in the glass matrix are mainly H+ or D+. Concerning the hydration kinetics, they evolve exponentially with time in the first stages of the alteration. Moreover, at 50 °C, the hydration follows a linear trend below 83% RH and strongly increases for higher RH values.
Uploads
Papers by Nathalie Valle