Atomic Energy of Canada Limited

About: Atomic Energy of Canada Limited is a company organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Neutron & Zirconium alloy. The organization has 4845 authors who have published 4826 publications receiving 102951 citations.

Coplanar capacitance sensors for detecting water intrusion in composite structures

Abstract: Composite materials are becoming more affordable and widely used for retrofitting, rehabilitating and repairing reinforced concrete structures designed and constructed under older specifications. However, the mechanical properties and long-term durability of composite materials may degrade severely in the presence of water intrusion. This study presents a new non-destructive evaluation (NDE) technique for detecting the water intrusion in composite structures by evaluating the dielectric properties of different composite system constituent materials. The variation in the dielectric signatures was employed to design a coplanar capacitance sensor with high sensitivity to detect such defects. An analytical model was used to study the effect of the sensor geometry on the output signal and to optimize sensor design. A finite element model was developed to validate analytical results and to evaluate other sensor design-related parameters. Experimental testing of a concrete specimen wrapped with composite laminate and containing a series of pre-induced water intrusion defects was conducted in order to validate the concept of the new technique. Experimental data showed excellent agreement with the finite element model predictions and confirmed sensor performance.

Direct measurement of the Si–O bond length and orientational disorder in the high-temperature phase of cristobalite

Abstract: Neutron total scattering measurements from powdered samples of cristobalite have been used to determine the local structure in both the tetragonal and cubic phases. The results for the cubic phase show directly that the Si–O bonds are tilted at an angle of around 17° to the unit cell [111] direction. It is striking that the structure of β-cristobalite over the range 5–10 A is closer to that of silica glass than α-cristobalite, which suggests that the local structure of β-cristobalite is not likely to consist of domains with the structure of α-cristobalite. The measurements show a small thermal expansion of the Si–O bonds over the temperature range 570–950 K.

Nanometer scale chemomechanical characterization of antiwear films

Abstract: We report the first nanometer scale chemical and mechanical (chemomechanical) characterization of selected features of a tribologically derived zinc dialkyl-dithiophosphate (ZDDP) antiwear film. AFM permits identification of the features responsible for preventing wear. These features are identified by nearby microscale fiducial marks, and their mechanical properties are determined by imaging nanoindentation. The same features are then studied by X-ray photoelectron emission microscopy (X-PEEM), which provides both elemental and chemical information at ∼200 nm spatial resolution. The mechanical properties are then determined for the same features, which are formed of a polyphosphate glass. This information provides new insights into the mechanisms by which ZDDP antiwears films are effective at inhibiting asperity contact between two metal surfaces

Atomic distribution in liquid and solid neon and solid argon by neutron diffraction

Abstract: The angular distribution of ${1.06}_{4}$ A neutrons scattered from liquid neon at 26.0\ifmmode\pm\else\textpm\fi{}1.5\ifmmode^\circ\else\textdegree\fi{}K and 1.7 atmospheres and that from solid neon and solid argon at 4.2\ifmmode^\circ\else\textdegree\fi{}K were measured over the angular range 5\ifmmode^\circ\else\textdegree\fi{} to 64\ifmmode^\circ\else\textdegree\fi{}. The transmission cross section of liquid neon was also measured and is 2.7\ifmmode\pm\else\textpm\fi{}0.3 barns for ${1.06}_{4}$ A neutrons.The scattering pattern and corresponding distribution function $4\ensuremath{\pi}{r}^{2}[\ensuremath{\rho}(r)\ensuremath{-}{\ensuremath{\rho}}_{0}]$ for liquid neon are similar in form to those of other measured inert gases. A study of the distribution function gives 2.45 A, 3.17 A and 8.8 for the nearest distance of approach of two atoms, the most probable separation of, and the number of neighbors under, the first shell of atoms, respectively. It is concluded that the effective potential in the liquid has a broader bowl than that of the Lennard-Jones 12:6 and other similar potentials.The lattice parameters ${a}_{0}$ for the f.c.c. structures of solid neon and solid argon are ${4.42}_{9}$ A and ${5.25}_{6}$ A, respectively. The Debye temperature for solid neon corresponding to the intensity of the diffraction maxima is 73\ifmmode^\circ\else\textdegree\fi{}K. The results suggest that the density change during the solid-liquid transformation cannot be accounted for by either a uniform depletion of atoms from, or a uniform dilation of, a basic structure.