Pd–Al interaction at elevated temperatures: a TEM and SAED study

Epitaxially grown Pd particles partly embedded in amorphous Al₂O₃ were subjected to annealing and reductive treatments in the temperature range 523–873 K to induce a possible Pd–Al interaction. The structural, morphological and compositional changes were monitored by transmission electron microscopy and selected area electron diffraction. Formation of Pd₄Al₃ and PdAl alloys has been observed upon annealing in 1 bar He for 1 h at T > 523 K and upon reduction in 1 bar H₂ for 1 h at T ≥ 523 K, respectively. Both alloys appear to be stable up to 873 K, although Pd₄Al₃ shows beginning decomposition at and above 873 K. The stability under oxidative conditions was found to be very similar, a transformation back into metallic Pd sets in for both compounds at around 573–623 K. In agreement with previous studies on Pd/SiO₂, the formation of an amorphous hydride phase and/or a heavily distorted Pd lattice has been detected after reduction in hydrogen at 523 K.     

Substrate Strengthening of CVD Coated Steels

CHEMICAL VAPOR DEPOSITION is successfullyused in production since decades to enhance the wearresistance of tools.Excellent coating properties areachieved with relatively simple equipment.The highdeposition temperatures used for CVD favor a goodadhesion of CVD coatings on the substrate,but alsonegatively influence the properties of the steelsubstrates.High coating temperatures followed byrelatively low cooling rates demand a subsequent heattreatment to restore the properties of the s…     

Control of Lamellae Spacing During Freeze Casting of Ceramics Using Double-Side Cooling as a Novel Processing Route

A processing route for freeze-casting of particle suspensions is presented, where the microstructure development during the solidification process can be controlled precisely. For this purpose, the single-side cooling and double-side cooling methods are compared. A procedure will be shown to control the freezing process using the double-side cooling method. Our approach was to determine the freezing conditions in order to forecast the freezing velocity and to carry out an advanced directional solidification setup for the experimental realization. Using this setup and the theoretical knowledge, the microstructure development can be controlled during the whole freezing process over a length of several centimeters.     

Mechanical Behavior of a Borosilicate Glass Under Aqueous Corrosion

In France, fission products are being vitrified for a possible final geological disposal. Under disposal conditions, corrosion of the glass by groundwater as well as stress corrosion because of stresses occurring at surface flaws cannot be excluded. Within this framework, the mechanical behavior of the French simulated nuclear waste glass SON68 was studied by Vickers indentation and fracture experiments in air and in a corrosive solution. The glass was corroded at 90°C in a solution enriched with Si, B, and Na. The results showed that the glass corrosion enhances the cracks propagation relative to experiments in air. The indentation fracture toughness ( K _{I C} ) obtained using a four-point bending test showed that the K _{I C} of the glass decreased with increasing corrosion time.     

Lead Zirconate Titanate–Magnetoplumbite Composites: A First Step Toward Multiferroic Ceramics?

When lead zirconate titanate (PZT) is acceptor doped way above the solubility limit of Fe³⁺, crystalline secondary phases become thermodynamically stable that are antiferromagnetic and ferromagnetic, i.e., plumboferrite, PbFe₄O₇, and magnetoplumbite (MP), PbFe₁₂O₁₉, respectively. Three materials were studied by X-ray diffractometry and transmission electron microscopy, with 3 mol% Fe (B-site) and high volume fractions of iron, which corresponds to a 1.5 and 6 mol% of MP addition, with emphasis placed on the phase and microstructure evolution, depending on the dopant level. Although the addition of the high iron content resulted in the formation of the desired ferromagnetic phase MP, homogeneously dispersed within the PZT host matrix, the densification kinetics became quite sluggish, resulting in rather porous multiferroic ceramics.     

Changes in the processing quality of sugar beet (Beta vulgaris L.) during long-term storage under controlled conditions

Long-term storage of sugar beet is an option to extend the processing campaign of the sugar factories in Europe. In the present study, changes in the processing quality of sugar beet were quantified during 110 days of storage at 7 and 20 °C. During storage, the concentration of sucrose decreased whereas K, Na, amino N, betaine, invert sugar and raffinose accumulated in the beets, i.e. quality was impaired markedly. At 7 °C, the changes in sucrose concentration were relatively small but the formation of invert sugar and raffinose caused considerable losses in beet quality. Thus, long-term storage at low temperature is appropriate to prolong the campaign but processing costs will increase. Quality assessment with two formulae showed that measurements of K, Na and amino N are insufficient to evaluate stored sugar beets for recoverable sugar. Due to its increase in storage, the concentration of invert sugar should also be taken into account.     

New computation method for stratification pipes of solar storage tanks

The efficiency of low-flow solar systems is strongly influenced by the quality of the thermal stratification in the storage tank. The better a thermal stratification can be generated and maintained, the higher can be the yield of the solar system. Fluid mechanical charge systems are often used for this purpose, which cause, however, undesirable sucking effects. Therefore, the knowledge of the appearing fluid flows as well as the knowledge of the consequences of constructive changes are very important for the design of such charge systems. However, simulations with CFD (Computational Fluid Dynamics) are very costly and time-consuming. In this article a new and much simpler computation method is introduced making the determination of the individual fluid flows and the estimation of the effects of constructive changes possible. The computations can be carried out within short time. The comparison with CFD gives a qualitatively good agreement for a simple charge system. The results of a constructive modification of the charge system reducing the sucking effect are discussed. The remaining quantitative differences result from the discrepancies between the non-ideal behaviour of the real fluid and the model assumptions and point out improvement potentials.     

Financial Risk Analysis of Project Finance in Indonesian Toll Roads

If a project is implemented using a project-finance approach, the debt service payment relies solely on the project cash flows and its assets. This paper identifies, quantifies, and evaluates major financial risks associated with project-financed toll road projects in Indonesia. Ordering payments by priority level, subject to cash availability, enables risk to be evaluated from the different perspectives of multiple parties involved. The paper makes use of Latin Hypercube simulations for risk analysis because they deal with problems involving large and complex systems. To better illustrate the concept, a case study is presented. A sensitivity analysis of the impact of delay-in-adjustment risk and of the adoption of a new regulation related to the toll adjustment is performed and discussed. Simulation results show that the project sponsor fares worse as delay-in-adjustment risk increases but that the creditor can fare better, given that the risk level is low or moderate. Output statistics also reveal that the adoption of the new regulation has negative impact on the project cash flows from both the project sponsor’s and the creditor’s perspectives under different scenarios associated with delay-in-adjustment risk.