Modulated IR radiometry as a tool for the thickness control of coatings

The thickness of coatings can be determined using the data measured by Modulated IR Radiometry for sets of coatings, produced under specific controlled conditions: – Keeping constant all deposition parameters except the deposition time, coatings of approximately constant thermal transport properties, but different thickness are produced. The modulated IR phase lag signals measured for the coatings are calibrated with the help of signals obtained for homogeneous opaque reference samples of smooth surface. Quantitative results for the thermal transport properties are obtained using the inverse solution of the 2-layer thermal wave problem by which direct relations are established between the relative extrema of the inverse calibrated thermal wave phase signals measured as a function of the heating modulation frequency and the thermal coating parameters, the ratio of the effusivities coating-to-substrate, the coating's thermal diffusion time, and the coating thickness. The coating thickness values obtained by Modulated IR Radiometry are compared with the values measured by standard microscopic methods, and relative errors of 3 – 4% have been found for the coating thickness of a set of TiCO coatings on steel, presented here as an example.(undefined

Effect of milling on morphology of molten salt synthesized Sr3Ti2O7 crystals

Effect of milling liquid (acetone and ethanol), and milling times on morphology of Sr3Ti2O7 (ST7) crystals grow in molten potassium chloride salt at 1250oC for 4 h was investigated. Two kinds of crystals with different morphologies were found: ST7 crystals having a tabular shape of less than 20 μm diameter and small secondary-phase crystals having high symmetry. Milling starting materials in ethanol yielded ST7 crystals that were up to 3 times thinner than those milled with acetone, increasing the (00l) Lotgering factor almost twice that when prepared with acetone. Large crystals become a bit smaller and the number of small crystals increased when the milling time increased

FePt3 nanosuspension synthesized from different precursors – a morphological comparison by SAXS, DLS and TEM

Annealed iron-platinum (FePt) is ferromagnetic in a nanoscale regime which is necessary for energy and data storage, whereas the as-synthesized form of FePt-based nanoparticles exhibits superparamagnetism useful for biomedical applications. In this study, as-synthesized nanosuspensions from the reaction of Pt(acac)2 with Fe(acac)3 and Fe(hfac)3 are compared. X-ray diffraction (XRD) peaks for both samples are assigned to the FePt3 phase. As shown by transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS), nanoparticles synthesized by using Fe(acac)3 have a smaller average diameter, but larger polydispersity index and particle agglomerations. On the other hand, the nanoparticles synthesized by using Fe(hfac)3 can self-assemble into a longer range of patterned monolayer. Dynamic light scattering (DLS), measuring the size of cluster of nanoparticles as well as oleic acid and oleylamine at their surface, confirms that larger agglomerations in the sample were synthesized by using Fe(acac)3. In addition to the size distribution, magnetic properties were influenced by the composition of these nanoparticles

Characterization of the mechanical and thermal interface of copper films on carbon substrates modified by boron based interlayers

The manipulation of mechanical and thermal interfaces is essential for the design of modern composites. Amongst these are copper carbon composites which can exhibit excellent heat conductivities if the Cu/C interface is affected by a suitable interlayer to minimize the Thermal Contact Resistance (TCR) and to maximize the adhesion strength between Cu and C