Abstract: Refractory materials, in particular tungsten base materials are considered as primary candidates for structural high heat load applications in future nuclear fusion power plants. Promising helium-cooled divertor design outlines make use of their high heat conductivity and strength. The upper operating temperature limit is mainly defined by the onset of recrystallization but also by loss of creep strength. The lower operating temperature range is restricted by the use of steel parts for the in- and outlets as well as for the back-bone. Therefore, the most critical issue of tungsten materials in connection with structural divertor applications is the ductile-to-brittle transition. Another problem consists in the fact that especially refractory alloys show a strong correlation between microstructure and their manufacturing history. Since physical and mechanical properties are influenced by the underlying microstructure, refractory alloys can behave quite different, even if their chemical composition is the same. Therefore, creep and thermal conductivity have been investigated using typical commercial tungsten materials. Moreover, the fracture behavior of different tungsten based semi-finished products was characterized by standard Charpy tests which have been performed up to 1100 °C in vacuum. Due to their fabrication history (powder mixing, pressing, sintering, rolling, forging, or swaging) these materials have specific microstructures which lead different fracture modes. The influence of the microstructure characteristics like grain size, anisotropy, texture, or chemical composition has been studied.

Abstract: Since the 1970's, global efforts have been going on to replace the high-enriched (>90% 235U), low-density UAlx research reactor fuel with high-density, low enriched (

Abstract: Thermal energy storage is an essential advantage of solar thermal power plants. The present paper focuses on latent heat storage using a phase change material (PCM). The paper lists literature and gives the current status of PCM work in the temperature range 200 to 350 °C. The system KNO3-NaNO3 is discussed in detail in terms of their thermo-physical properties in the liquid and solid phase. A comparison of literature data and own measurements for the density, heat capacity, thermal diffusivity and thermal conductivity is presented. Measurement results with the following methods are discussed: helium pycnometer, differential scanning calorimeter (DSC) and laser flash. Missing data of the thermal diffusivity and thermal conductivity are partly supplemented. Consistent thermo-physical properties in the liquid phase are presented.

Abstract: Functionally Grated Materials (FGMs) have usually been expected as candidates for a wide variety of industrial applications due to their desirable properties such as high heat resistance capability, good wear resistance, bio-compatibility, chemical stability and so on. Scaling-up and three dimensional (3-D) near-net shape forming technique for FGMs are one of the most important key-factor to produce the industrial engineering components and products in practical use. On the other hand, it is generally well known that the Spark Plasma Sintering (SPS) method is a novel process to produce homogeneous FGMs, nano-structural sintered compact, thermoelectric semiconductors and bio-medical materials in shorter sintering time with finer microstructure. This paper will present development of FGMs fabricated by SPS and future prospects of SPS on research and industrialization activities in Japan. A brief historical review progress of SPS technology is also given and the applicable field is exemplified. Then, the paper is focused on manufacturing processes on FGM by SPS technology.

Abstract: High-temperature thermochemical processes efficiently convert concentrated solar energy into storable and transportable fuels. In the long run, H2O/CO2-splitting thermochemical cycles based on metal oxide redox reactions are developed to produce H2 and CO, which can be further processed to synthetic liquid fuels. In a transition period, carbonaceous feedstocks (fossil fuels, biomass, C-containing wastes) are solar-upgraded and transformed into valuable fuels via reforming, gasification and decomposition processes. The most promising solar thermochemical processes are discussed and the latest technological developments are summarized.

Abstract: I-129 is a very long-lived radionuclide that is released to an off-gas stream when spent fuels are dissolved at a reprocessing plant. An iodine filter can capture I-129 in the form of AgI. However, because AgI is unstable under the reducing conditions of a geological repository and I-129 has a very long half-life, I-129 can migrate to the biosphere. These characteristics make I-129 a key radionuclide for the safety assessment of a geological disposal of radioactive wastes generated from a reprocessing plant (TRU wastes). To improve disposal safety, several new waste forms have been developed to confine I-129 for a very long period in order to reduce the leaching of I-129 from radioactive wastes. These new waste forms have technical objectives of solidifying more than 95% of I-129 into the waste form and achieving a leaching rate of less than 10-5/y. Several iodine immobilization techniques have been examined. This paper presents experimental results concerning the treatment process, leaching behavior, modeling, and related elements of these immobilization techniques.

Abstract: Hexagonal boron nitride (h-BN) is a very versatile material that is used in a number of applications due to its unique combination of properties. This paper reviews typical h-BN qualities and their applications as functional particle in coatings and as sintered parts. As an example, the EKamold® coating family is presented in detail for a variety of substrate types and applications. Furthermore a general overview is given of the effect of the binder phase for hot-pressed h-BN qualities. And finally the use of h-BN as a composite with a) zirconium oxide for side dams in steel thin-strip casting and b) with titanium diboride as evaporation boats is described in more detail.

Abstract: In contrast with metals, the resistivity of ceramics decreases with increasing temperatures. This phenomenon was first discovered in 1833 by Faraday and remained a mere scientific curiosity until 1930, when Samuel Ruben proposed the fabrication of a pyrometer device, which explored the negative temperature coefficient (NTC) of resistance exhibit by Cu2O. Eight decades later, NTC ceramic thermistors constitute an important business segment for most electroceramic manufacturers. Here, we present a review of the most significant scientific and technological advances, which lead to the enormous commercial success of NTC thermistors. This review concludes with an outlook into future possible applications of NTC ceramics, providing that some current technological shortcomings (such as ageing) are resolved.

Abstract: Geopolymer is an inorganic alumino-silicate product that shows good bonding properties. Geopolymer binders are used together with aggregates to produce geopolymer concrete which is an ideal building material for infrastructures. A by-product material such as fly ash is mixed together with an alkali to produce geopolymer. Current research on geopolymer concrete has shown potential of the material for construction of reinforced concrete structures. Structural performance of reinforced concrete depends on the bond between concrete and the reinforcing steel. Design provisions of reinforced concrete as a composite material are based on the bond strength between concrete and steel. Since geopolymer binder is chemically different from Ordinary Portland Cement (OPC) binder, it is necessary to understand the bond strength between geopolymer concrete and steel reinforcement for its application to reinforced concrete structures. Pull out test is commonly used to evaluate the bond strength between concrete and reinforcing steel. This paper describes the results of the pull out tests carried out to investigate the bond strength between fly ash based geopolymer concrete and steel reinforcing bars. Beam end specimens in accordance with the ASTM Standard A944 were used for the tests. In the experimental program, 24 geopolymer concrete and 24 OPC concrete specimens were tested for pull out. The concrete compressive strength varied from 25 to 55 MPa. The other test parameters were concrete cover and bar diameter. The reinforcing steel was 500 MPa steel deformed bars of 20 mm and 24 mm diameter. The concrete cover to bar diameter ratio varied from 1.71 to 3.62. It was found from the test results that the failure occurred by splitting of concrete in the region bonded with the steel bar, in both geopolymer and OPC concrete specimens. Comparison of the test results shows that geopolymer concrete has higher bond strength than OPC concrete. This suggests that the existing design equations for bond strength of OPC concrete with steel reinforcing bars can be conservatively used for calculation of bond strength of geopolymer concrete.

Abstract: The denomination ‘flexible’ is chosen in the professional jargon of refractories technology for materials able to bear relatively high strains without or with acceptable loss of strength. In many cases this term is equivalent to relatively low brittleness. Characterisation of brittleness based on fracture mechanical investigations may use figures of merit like brittleness numbers, a so called characteristic length or the R’’’’ parameter according to Hasselman. In many cases these figures show that brittleness reduction of refractories is achieved by decrease of strength with at the same time more or less unaffected specific fracture energy. Microscopic investigations of fracture paths aim to exhibit which peculiarities of crack microstructure enable this change of mechanical properties. A microscopical technique developed for this purpose separately evaluates the relative crack lengths along the grain/matrix interface, within the matrix and within the grain. Results obtained for several types of refractories show brittleness decrease is associated by an increase of the relative crack length along the grain/matrix interface and a decrease of transgranular fracture. Prefabricated microcracks and a relatively low grain/matrix bond strength may support this type of crack propagation.

Abstract: In order to improve the oxygen permeation rates of oxygen transport membranes (OTM), asymmetric membranes with a thin dense layer must be fabricated on a porous support. In this paper, we focus on preparing and characterizing structures with functional layers consisting of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and La0.68Sr0.3Fe0.8Co0.2O3-δ (LSFC). The supports for these structures were prepared by tape casting and warm pressing, and samples were analysed in terms of nitrogen permeability and porosity. The coating of the functional layers was performed via screen printing. For BSCF, multiple layers were necessary to obtain a gas-tight structure. Oxygen permeation measurements of the asymmetric structures showed an increase in the oxygen flux in comparison to bulk membranes with a thickness of L =1 mm. However, this enhancement is subproportional to the reduced thickness, indicating rate limiting effects, i.e. surface exchange kinetics in the case of LSFC and concentration polarization in the porous support in the case of BSCF.

Abstract: Concentrating Solar Power Technology (CSP) is nowadays growing mainly due to the technical and economic success of the first projects and to the stable green pricing or support mechanisms that bridges the initial gap in electricity costs (i.e. feed-in tariffs). Future growth will depend on a successful cost reduction and on a strong effort in R&D to optimize the potential for technical improvement [1]. Testing of new materials, components and systems is still of key importance to drive research and innovation improvements to a commercial stage. Receiver manufacturers are investing in R&D in order to improve performances and reduce costs, while project developers are demanding standards to help them evaluate satisfactorily the risks and the benefits of introducing new developments in commercial power plants. The Solar Thermal Energy Department, of the National Renewable Energy Centre (CENER) and the Applied Optics Department of the Universidad de Zaragoza (UZ) have joined efforts to develop a characterization equipment able to measure as far as possible most of the receiver optical and thermal properties. In this paper the testing facility developed by CENER-UZ is described technically. The methodology for optical and thermal characterization of solar receivers for parabolic trough collectors is explained and the preliminary results are presented and discussed in detail.

Abstract: The production of confined or adsorbed drugs in inorganic matrix has been increasing in areas like material science and pharmaceutical due to the possibility of the production of nanoadsorbed or encapsulated molecules with new properties like chemical stability, enhancing solubility and controlled release, what implies in new applications of materials. In the present work, a nanocomposite of a fine ceramic material, pseudoboehmite, and acyclovir, was prepared. Pseudoboehmite is based on a monohydroxide aluminum oxide produced from a synthetic route using ammonium hydroxide and aluminum nitrate or chloride as precursors in the sol-gel process. These systems had been characterized by the following techniques: MEV, TG/DSC, FTIR and UV-vis. The exposition of the drug to the pseudoboehmite at the dissolution equipment was at 37°C and 100rpm for 30 minutes. With the purpose to observe the interaction of the drug with the adsorbent, it was obtained the concentration of the drug in the solution, before and after the adsorption, using the UV-vis spectroscopy technique. The acyclovir has increased its solubility in an HCl 0,1M solution, when the weight ratio of Pseudoboehmite: Acyclovir 1:1 was used.

Abstract: Magnetic susceptibility measurements, magnetization and neutron diffraction results at low temperature for cobalt and manganese oxide spinel ceramics are presented. The Curie temperature varies similarly with the sample composition in ceramics and powders. The experimental molar Curie constant variation is explained by the presence of Co2+, CoIII, Mn3+ and Mn4+, and possibly Co3+ in the octahedral sites for the cobalt rich phases. The magnetic moments of the cations in tetrahedral and octahedral sites are not collinear and the global magnetization is oriented in a third direction.

Abstract: In this work, the sol-gel technology is used to produce silica based xerogels and aerogels suitable for insulation applications in Space. The properties of the obtained materials are tailored varying the precursor – Methyltrimethoxysilane (MTMS) or Methyltriethoxysilane (MTES), and the solvent – methanol or ethanol. A two-step acid-base catalyzed synthesis is used, being the obtained gels dried at atmospheric pressure, in the case of xerogels, and in supercritical conditions, for aerogels. Density and thermal conductivity must be made as low as possible for the sought application and only highly porous materials can fulfill this requirement. The obtained xerogels and aerogels, either with MTMS or MTES, show very promising properties for thermal insulation in Space, when methanol is used as solvent. The more suitable materials are obtained with MTMS and exhibit very low density (80-100 kg/m3), very high surface area (~ 400 m2/g) and small pore size (~ 30-40 A). They also show moderate flexibility and a remarkable hydrophobic character (~ 150o).

Abstract: The CaZrO3 complex oxide ceramic was synthesized in the development of the potential refractory for melting of titanium alloy, the crucible ( 40XH40mm) was prepared by the solid sintering of mixture of powder (CaO:ZrO2 =1:1) with a small amount of TiO2 as additive at 1750°C. The melting of TiNi and Ti6Al4V was carried out in the inducting furnace under vacuum or/and Ar atmosphere. The interfacial reaction between the melts of alloys and CaZrO3 refractory was investigated by scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS). It is found that, the thickness of interfacial reaction layer between the ceramic CaZrO3 and the melt of titanium alloys (TiNi and Ti6Al4V) is approximately 30-300 μm, there are few elements such as Ca, Zr, Ti, and Ni diffused through the interfacial reaction layer. These results may provide the basement to designing a novel refractory for melting of titanium alloys.

Abstract: Electric arc furnace slag (EAF-S), coming from a steel productive plant in Italy, has been used as new source for geopolymers synthesis. The slag has been geopolymerized alone and with different content of metakaolin (MK) with the aim to investigate if EAF-S content plays a role in geopolymerization process. Mechanical properties results and microstructure analysis highlight that the optimum weight ratio MK/EAF-S to be used as starting materials is 40/60, 30/70, 20/80. Moreover EAF-S, when used with MK, directly participates in the formation of calcium-rich alumino-silicate gels.

Abstract: Geopolymer concrete with designed strength of 40 Mpa has been mixed from coarse aggregates, sands and geopolymer pastes. Two kinds of pastes are synthesized from different precursors, i.e. fly ash and dehydroxylated kaolin, using sodium silicate solution as the activator. Compression test pieces of 15x15x15 cm3 of both geopolymer and ordinary Portland cement (OPC) concretes (ASTM C39) have been cast and cured. Curing was done at room temperature for 1 day while Portland cement concretes were immersed in water for 28 days to provide complete hydration. After curing, the samples were immersed in ASTM seawater (ASTM D1141-90) for 7, 28, 56 and 90 days. It is found that geopolymer concretes were in general more durable upon seawater immersion than OPC concrete, This is indicated by the compressive strength retained after immersion. Dehydroxylated kaolin geopolymers show the best performance whose strength did not decrease with time of immersion. The strength of fly ash geopolymers decreased by about 20% during 56-day immersion but did not decrease further. Calcium content is suspected to cause the decrease in strength upon immersion. Kaolin geopolymers containing no calcium showed the best performance, while OPC which consist mostly of calcium silicate hydrates as the strength contributor, showed consistent decrease in strength. It is also found from the experiment that room temperature curing of fly ash geopolymer was slow but continued to progress until 28 days both under dry condition (not immersed) and immersed in water.

Abstract: A sago-based gel polymer electrolyte (GPE) was prepared by mixing native sago with potassium hydroxide (KOH) aqueous in order to investigate the applicability of GPE to zinc-air (Zn-air) battery. The viscosity and conductivity of the sago GPE were evaluated using varying sago amounts and KOH concentrations. The viscosity of the sago GPE was kept as a reserve in the region of ~ 0.2 Pa s as the KOH concentration was increased from 2 to 8 M. Sago GPE was found to have an excellent ionic conductivity of (4.45  0.1) x 10-1 S cm-1 with 6 M KOH. GPE was also employed in an experimental Znair battery using porous Zn electrode as the anode. The battery shows outstanding discharge capacity and practical capacity obtained of 505 mA h g-1.

Abstract: We studied the different carrier kinetic mechanisms involved into the interband absorption of quantum dots (QDs) by photocurrent spectroscopy. It was shown that in vertically coupled InGaAs QDs an effective carrier emission, collection and separation take place due to minizone formation. The possibility for the incorporation of vertically-coupled QDs into solar cells (SC) without any deterioration of structural quality of the p-i-n-junction has been shown. Due to the additional absorption of solar spectrum in QD media and the subsequent effective separation of photogenerated carriers, an increase (~1%) in short-circuit current density (Jsc) for the QD SC-devices has been demonstrated. However the insertion of QDs into intrinsic region reduced the open circuit voltage (Voc) of such devices. Moving the QD array in the base layer as well as including the Bragg reflector (BR) centered on 920 nm resulted in increase of the Voc. Moreover an improved absorption in the QD media for SC with BR led to further increase of Jsc (~1%). The efficiency for QD SCs at the level of 25% (30 suns AM1.5D) has been demonstrated.

Abstract: During the last years large efforts were made, to get able to supply large and complex components made of gas pressure sintered silicon nitride. This opened new applications for such ceramic materials in ambient and very harsh environment and generated new markets for ceramic producers. The paper presents, a newly developed rapid prototyping routine for complex components as well as the properties of corresponding materials. Components for innovative avionic and space applications, dynamic materials testing, liquid metal processing, metal forming and mechanical engineering are shown. Not only unique properties of the material itself, but also newly developed and adopted shaping and machining technologies for this specific ceramics have let to highly valued products. Due to its very specific set of material properties, silicon nitride has gained a lot of interest. New approaches in technical equipment were undertaken with corresponding research. However, except of seals, bearings and cutting tools, none of all expected high volume applications is industrialized. On the other side, a lot of less spectacular applications are state of the art today. They have opened a wide field for niche products and lead to technical solutions with less wear and corrosion but improved products.

Abstract: Kaolinite (2SiO2Al2O32H¬¬¬¬2O), an aluminosilicate mineral, is the most common constituent mineral in clay used in manufacturing traditional ceramics such as whitewares, some refractories and structural clay products On firing, kaolin (mainly kaolinite) undergoes several phase transformations Immediately following firing, kaolin starts to chemically combine with atmospheric moisture This reaction causes a mass increase that is proportional to the fourth root of time The consequence of this mass gain is an accompanying expansive strain Kaolinite transformations following firing at a range of temperatures between 700 and 1200 oC were examined by XRD Following firing, high accuracy mass gain measurements were carried out using a microbalance under precisely controlled conditions of temperature and relative humidity It was found that the formation and development of crystalline phases increases with increasing firing temperature This causes a reduction in the amorphous phase which, in turn, leads to reduced mass gain Kaolin fired at 1200 oC exhibited the least reactivity with moisture and mullite was found to be the dominant crystalline phase after firing at that temperature SEM was used to examine microstructural changes in the fired specimens The reactivity of the ceramic with moisture is shown to be directly related to the crystallinity of the fired clay

Abstract: This work is devoted to the study of the geometrical stability in time of UyAm1-yO2-x pellet due to self-irradiation at room temperature. Dense and tailored porosity U1-yAmyO2-x (y=0.10; 0.15) compounds were fabricated by a powder metallurgy process. Up to 3.4.1017 α particles/g, an increase in the diameter of 0.9% was observed for the dense compounds while for the tailored porosity material a diameter increase of 0.4% was observed. Swelling laws have been established from the experimental data.

Abstract: In this work three samples of MSWI ash have been stabilized in systems containing coal fly ash and able to give geopolymers through a polycondensation reaction. Monolithic products were obtained with both MSWI ashes as received and after chloride partial removal by water washing. The polycondensation products have been characterized qualitatively by means of FT-IR spectroscopy and scanning electron microscopy (SEM) and quantitatively through the determination of the amount of reacted water and silicate. Differently from traditional cement based stabilization systems, those based on geopolymerization show a chemical behaviour almost insensitive to the presence of chlorides and sulphates in the MSWI ash. On the other hand, the microstructure is strongly affected by the content of soluble salts.

Abstract: Studies of titanium and its alloys commonly used as biomaterials aim to improve bone-implant interface related problems, which may determine the quality, bone repairing time and therefore the implant clinical success. The goal of this study was to evaluate, in rats, osseointegration of macroporous implants produced by powder metallurgy (PM) method with controlled addition of gelatin. As control group, samples of commercially pure titanium (cpTi) and Ti-13Nb-13Zr alloy obtained by the PM process were used. To obtaining the porous samples, at most 15% in weight of gelatin was added to metallic powders, the samples were thermally treated in vacuum furnace, and sintered at 1150°C. The osseointegration evaluation was performed in Wistar rats, males, for a 28 days period. The morphological analyses, optical microscopy and scanning electron microscopy (SEM), evaluated qualitatively the osseointegration. The PM process modified by addition of gelatin provides with success the obtaining of porous metallic implants. Pore size obtained by this technique allowed the necessary nourishing to cell survival, proving that pores and channels form a high interconnectable network represented by the osseointegration and osteoconduction feature of the porous alloy.

Abstract: Although blade coating materials dissipate vibratory energy while acting as thermal barrier coatings or protecting the substrate against corrosion or erosion, the inherent nonlinearity of these materials complicates the determination of the necessary material parameters. While plasma-sprayed ceramics alone do not appear to provide the desired levels of dissipation, notable increases in damping have been found to result from the inclusion of small amounts of viscoelastic materials. With proper selection of the added component, the resulting coating may be tailored for high damping in a specific temperature range. Vacuum infiltration of polymeric components into plasma-sprayed ceramics raise the dissipation to desired levels for temperatures of 93-135 oC; co-spraying mixtures of ceramics and glass frits leads to extremely high damping in the transition range of the glass, typically 550-800 oC.

Abstract: The medium to long term engineering performance of high-strength geopolymer concrete systems are largely dependent on fluid ingress and the transport phenomena that govern permeability of structural members exposed to aggressive environments. For the purpose of analysing durability performance, both high pressure water and gas permeability testing of fly-ash geopolymer(GP) concretes have been assessed for samples cured under ambient and steam exposure conditions at 65OC. The observed mean permeability coefficient values for gas(k) and water(Kw) of steam-cured structural grade concrete was respectively 6.19E-17m2 at 300kPa gas pressure and 1.52E-10m/s at 525kPa water pressure. While mean gas permeability values were comparable to reference steam-cured ordinary Portland cement(OPC) systems, the corresponding water permeability coefficient data for geopolymer concrete was ten-fold higher. The transport properties of OPC concrete systems are typically governed by water-to-cement ratio and the degree of hydration which is linked to the level of porosity and pore interconnectivity. However, corresponding permeability of geopolymer concrete appears to be dictated by an inherent mesoporous capillary pore network structure for which transport properties appear to be partly dependent on mode of concrete curing. The Paper examines global implications of increased permeability and key durability parameters such as chloride diffusion, carbonation rates and steel reinforcement corrosion on long-term engineering and durability performance.

Abstract: In order to be used for applications, the thermodynamic stability of a candidate hydrogen storage material should be suitable for hydrogen sorption at room conditions. By mixing different hydrides, it is possible to promote the hydrogenation/dehydrogenation processes. On the other hand, small changes in composition allow a tailoring of thermodynamic stability of hydrides. Knowledge of thermodynamic stability of hydrides is thus fundamental to study the hydrogenation/dehydrogenation processes and useful to rationalize synthesis reactions and to suggest possible alternative reaction routes. The purpose of this work is to develop a consistent thermodynamic database for hydrogen storage systems by the CALPHAD approach. Experimental data have been collected from the literature. When experimental measurements were scarce or completely lacking, estimations of the energy of formation of hydrides have been obtained by ab initio calculations performed with the CRYSTAL code. Several systems of interest for hydrogen storage have been investigated, including metallic hydrides (M-H) and complex hydrides. The effect on thermodynamic properties of fluorine-to-hydrogen substitution in some simple hydrides is also considered. Calculated and experimental thermodynamic properties of various hydrides have been compared and a satisfactory agreement has been achieved.

Abstract: This study deals with the modelling of the mechanical behaviour accounting for the expansion induced by the oxygen diffusion in MIECs membrane during semi-permeation transient stage. A dedicated model of chemical expansion and its numerical implementation is used to study the relationship between the mechanical stress and the oxygen flux. The impact of the ratio between oxygen bulk diffusion and surface exchange kinetics on mechanical stress in transient stage is discussed. At last, the need of a compromise between the oxygen flux performance and the mechanical reliability is underlined.