Optimal Massing Liquid Volume Determination by Energy Consumption Measurement: Study of the Influence of Some Physical Properties of Solvents and Products Used

This study tried to investigate, by the power comsumption technique, the influence of the powder's and solvent's properties on wet granulation.

It could be shown that the required amount of granulation liquid decreases when the particle size of the powder to be granulated increases. This relationship is however only true when the particle size distribution of the powder to be granulated is rather narrow.

Powders having the same solubility in different solvents require the same optimal liquid quantity for granulation, but the properties of resulting granules depend on surface tension and wetting properties of the solvent.

When the powder to be granulated contains crystallisation water, the temperature rising in the mixer can be sufficient to liberate this water, which must be taken into account in the optimal granulation liquid requirement.

The effect of a macromolecular binder (PVP, HPMC) has also been studied: the optimal liquid quantity required changes with the kind of binder used and the manufacturing process (binder used in solution or added as dry powder).

It was also shown that in the case of lactose, the optimal quantity of PVP or HPMC can be determined from the power consumption records and from the granules friability studies     

Action of chelators on solid iron in phosphate-containing aqueous solutions

To study the effect of strong iron-ligands on steel corrosion, mild steel electrodes were immersed in solutions containing 20 mM phosphate buffer (pH=7.2) and between 0.01 mM and 1 M of either the iron(II)-chelators 2,2^′-bipyridine or FerroZine, or the iron(III)-chelators citrate or acetylacetonate. Resulting surface reactions were investigated by quantifying the electrochemical potential (E), the electrochemical polarization resistance (R_p), the corrosion current (I_corr) and the release of iron into solution. The surface was further analyzed by scanning electron microscopy (SEM/SEM-EDAX) and atomic force microscopy. Concentrations of 0.1 mM of any of the chelators led to slight, temporary changes in E, I_corr and R_p. Concentrations of 10 mM resulted in characteristic changes of E, which were the same for all chelators and in the precipitation of FePO₄ in the case of citrate and acetylacetonate, or vivianite [Fe₃(PO₄)₂ · 8H₂O] in the case of bipyridine and FerroZine. Concentrations of 1 mM of both iron(III)-chelators led to a temporary drop of E similar to that found with 0.1 mM chelator. With iron(II)-chelators, E dropped to about −500 mV before oscillating for several days. The amplitudes of the oscillations were up to 200 mV with periods of 30 and 20-25 min for bipyridine and FerroZine, respectively.     

Robust camera model identification using demosaicing residual features

Multimedia Tools and Applications - In this paper, we propose a new framework for performing accurate and robust camera model identification by fully exploiting demosaicing information in a...     

Thermal Mechanical Fatigue Behavior of Advanced Overlay Coatings

Environmental protection and cost effectiveness lead to the demand to increase the efficiency of energy conversion. In the past decade gas turbines have become an important factor in efficient power generation. Gas turbine inlet temperatures are being increased continuously to decrease the specific fuel consumption. The development of new base materials and sophisticated processes like single crystal solidification allows higher metal temperatures. This causes higher oxidative stress to the MCrAlY overlay coatings. As shown in an earlier paper (I), an improvement of the high temperature properties is achievable by the addition of Rhenium. In this paper we report on properl ies of MCrAlY coatings containing 8 to 12% Al and 10% Rhenium by weight. The coatings were applied on Inco 738 LC by LPPS (Low Pressure Plasma Spraying). Data for static oxidation and cyclic oxidation data at 950°C, I000°C up to 10,000 hours are presented. However, the main aim of this report is to discuss the thermal-mechanical properties of LPPS-coatings with Re. As known from earlier work, the variation or addition of different elements to overlay coatings lead to a change in the ductile-brittle transition. Ductile-Brittle-Transition-Temperature (DBTT) measurements on 10% Re containing systems under the variation of Co, Cr, Al and Si have been done. In order to get more information about the thermal-mechanical properties of the coating under service like conditions, TCF (Thermal Cycle Fatigue) and TMF (Thermal Mechanical Fatigue) tests were carried out. On discus shaped samples, the TCF behavior of an MCrAlYRe coating in comparison to an MCrAlY coating has been evaluated up to 1,500 cycles. The samples were heated in a radiation oven up to 1000°C and cooled down by compressed air. By this method a differentiation in the thermal fatigue behavior is possible. However, this kind of test does not cover all possible relaxation processes. A more realistic investigation of the thermal mechanical fatigue behavior is given by TMF tests. A service life cycle was taken to study the thermal mechanical behavior. It is shown that Re improves the thermal mechanical properties of MCrAlY coating systems considerably.     

Mechanical and electric fatigue of PZT(53/47) films on metallic substrates

Abstract

We have investigated the fatigue of electromechanical and dielectric properties of sol-gel derived PZT(53/47) thin films deposited on metallic substrates by means of electric and mechanical cycling. For the mechanical cycling a two point bending method was used to apply transversal stress to the samples. During mechanical cycling the piezoelectric coefficient d₃₁ remained constant up to about 10⁵ cycles, for a higher number of cycles a strong decrease was observed. During electric cycling no significant changes in the ferroelectric and electromechanical hysteresis loops could be found up to about 3×10⁵ cycles. Above this number the coercive field increases, the maximum strain and the remanent polarization decrease.

Obviously each electric cycling of the investigated films is accompanied by a mechanical cycling. It is assumed, that microcracks induced by mechanical stress are the main reason for the deterioration of the physical properties films during electric and mechanical cycling both.     

Influence of a cyclic butylene terephthalate oligomer on the processability and thermoelectric properties of polycarbonate/MWCNT nanocomposites

The thermoelectric properties of melt-processed nanocomposites consisting of a polycarbonate (PC) thermoplastic matrix filled with commercially available carboxyl (–COOH) functionalized multi-walled carbon nanotubes (MWCNTs) were evaluated. MWCNTs carrying carboxylic acid moieties (MWCNT-COOH) were used due the p-doping that the carboxyl groups facilitate, via electron withdrawing from the electron-rich π-conjugated system. Preliminary thermogravimetric analysis (TGA) of MWCNT-COOH revealed that the melt-mixing was limited at low temperatures due to thermal decomposition of the MWCNT functional groups. Therefore, PC was mixed with 2.5 wt% MWCNT-COOH (PC/MWCNT-COOH) at 240 °C and 270 °C. In order to reduce the polymer melt viscosity, a cyclic butylene terephthalate (CBT) oligomer was utilized as an additive, improving additionally the electrical conductivity of the nanocomposites. The melt rheological characterization of neat PC and PC/CBT blends demonstrated a significant decrease of the complex viscosity by the addition of CBT (10 wt%). Optical and transmission electron microscopy (OM, TEM) depicted an improved MWCNT dispersion in the PC/CBT polymer blend. The electrical conductivity was remarkably higher for the PC/MWCNT-COOH/CBT composites compared to the PC/MWCNT-COOH ones. Namely, the PC/MWCNT-COOH/CBT processed at 270 °C exhibited the best values with electrical conductivity; σ = 0.05 S/m, Seebeck coefficient; S = 13.55 μV/K, power factor; PF = 7.60 × 10⁻⁶μW/m K⁻², and thermoelectric figure of merit; ZT = 7.94 × 10⁻⁹. The PC/MWCNT-COOH/CBT nanocomposites could be ideal candidates for large-scale thermal energy harvesting, even though the presently obtained ZT values are still too low for commercial applications.