Full-field pulsed magneto-photoelasticity – Experimental Implementation

This paper contains a description of the experimental procedure employed when using a pulsed-magneto-polariscope (PMP) and some initial full-field through-thickness measurements of the stress distribution present in samples containing 3D stresses. The instrument uses the theory of magneto-photoelasticity (MPE), which is an experimental stress analysis technique that involves the application of a magnetic field to a birefringent model within a polariscope. MPE was developed for through-thickness stress measurement where the integrated through-thickness birefringent measurement disguises the actual stress distribution. MPE is mainly used in toughened glass where the through-thickness distribution can reduce its overall strength and so its determination is important. To date MPE has been a single-point 2D through-thickness measurement and the analysis time is prohibitive for the investigation of an area which may contain high localised stresses. The pulsed-magneto-polariscope (PMP) has been designed to enable the application of full-field 3D MPE [ ]. Using a proof-of concept PMP several experimental measurements were made, these were promising and demonstrate the potential of the new instrument. Further development of this technique presents several exciting possibilities including a tool for the measurement of the distribution of principal stress difference seen in a general 3D model

Silver particle nucleation and growth at liquid/liquid interfaces: a scanning electrochemical microscopy approach

Scanning electrochemical microscopy (SECM) has been used to induce and monitor the electrodeposition of silver particles at a liquid/liquid interface by the electron transfer reaction between aqueous Ag+ ions, generated by anodic dissolution of an Ag disk ultramicroelectrode (UME), and bis(pentamethylcyclopentadienyl) iron (decamethylferrocene, DMFc) in a 1,2-dichloroethane (DCE) phase. A two-electrode system with an Ag UME as the SECM tip was used to investigate the factors affecting the deposition process, such as the tip-interface separation, potential applied to the tip, concentration of the reductant in the DCE phase, and the reaction driving force, which was controlled by the concentration ratio of a common ion (ClO4-) in the two phases. A theoretical model was developed and rate constants for Ag particle nucleation and growth at the water/DCE interface were obtained by thorough analysis of experimental current-time curves. It was found that Ag+ ion adsorption at the interface, coupled to particle nucleation and growth, best described the experimental data. The growth of Ag particles at the liquid/liquid interface was confirmed by independent microscopy measurements