Calcium–magnesium–alumino-silicate (CMAS) particulates enter the aero-engine in a sandy environment, melt and infiltrate into 7 wt% yttria-stabilized zirconia (7YSZ) thermal barrier coatings (TBCs), reducing their lifetime. This leads to chemical degradation in 7YSZ accompanied by tetragonal to monoclinic phase transformation upon cooling. In this work, electron-beam physical vapor deposition coatings were infiltrated with a synthetic CMAS. Synchrotron X-ray diffraction measurements show that CMAS infiltration at 1250 °C has about 43% higher monoclinic phase volume fraction (PVF) at the coating surface compared to 1225 °C and remains consistently higher throughout the coating depth. Additionally, the increase in annealing time from 1 to 10 h results in a 31% higher monoclinic phase at the surface. Scanning electron microscopy revealed the presence of globular monoclinic phases corresponding spatially with the above findings. These results resolve the impact of time and temperature on CMAS infiltration kinetics which is important for mitigation.

In a new design approach, C/C–SiC sandwich structures have been realized via liquid silicon infiltration and in situ joining methods. In the first process step, the carbon fiber reinforced polymer preforms for the planar skin plates as well as for the core structures were manufactured via warm pressing and autoclave technique, using C fiber fabrics preimpregnated with phenolic resin. Thereby, two types of C/C–SiC core structures were used: foldcore and grid core. In the second process step, the sandwich components were pyrolyzed separately, leading to porous C/C preforms and subsequently joined to a C/C sandwich structure, using an adhesive. In the last process step, the C/C structure was infiltrated with molten Si, and the SiC matrix was built up by a chemical reaction of Si and C, leading to a permanently joined C/C–SiC sandwich structure. For mechanical characterization, sandwich specimens were manufactured and tested in 4 point bending.

Extremely hard, wear-resistant SiC-bonded diamond materials with diamond contents of approximately 45–60% by volume can be prepared by pressureless infiltration of shaped diamond compacts with silicon. Materials with diamond grain sizes in the range of 10–100 µm can be produced having a free silicon content of less than 5 vol%. Components with large dimensions can be prepared as graded or ungraded materials. Graded components are composed of silicon infiltrated SiC base material with diamond–SiC composite layers of 0.1 mm by dip coating technology to several mm in thickness by doubled die pressing in regions with high loading. This creates the possibility of producing low-cost, wear-resistant components of various geometries and dimensions with bending strengths of 400–500 MPa, hardness values of 48 GPa, and fracture toughness levels of 4.5–5 MPa m1/2 for use in extreme wear conditions. Thermal conductivities of up to 500 W/(m K) were obtained, render these materials interesting for heat sinks.

Twinned silicon carbide (SiC) nanowires (NWs) reinforced Si3N4–SiOC composites were successfully fabricated through a joint process of three-dimensional printing (3DP), direct nitridation, and polymer infiltration and pyrolysis (PIP). 3DP and PIP were both addictive manufacturing processes, enabling the near net shape fabrication and microstructure designing of Si3N4–SiOC. With the increase of the PIP cycle number, the pores of Si3N4 were mostly filled with polymer-derived ceramics-silicon oxycarbide (containing SiC NWs and free carbons), which led to the increase of electrical conductivity of Si3N4–SiOC composites. With the increase of SiOC ceramics, the electromagnetic interference shielding effectiveness of Si3N4–SiOC composites increased from 2 dB to 35 dB, in which the absorption shielding effectiveness increased to 27 dB. The flexural strength of Si3N4–SiOC composites reached 63 MPa when the content of SiOC ceramics was 50.1 wt%. It is indicated that Si3N4–SiOC ceramics are a promising electromagnetic shielding and structural material.

Fibrous polyethylene terephthalate (PET) was modified by organometallic vapor exposure to form hybrid materials with unique photoluminescent characteristics. Using a sequential vapor infiltration (SVI) process, the elongated exposures of trimethylaluminum (TMA) to PET were examined. As the infiltration temperature increased, the evidence of changes in the reaction between the organometallic vapor and the polymer was observed as well as significant changes in the infiltration depth into the polymer fiber, owing to the variation in the reaction mechanisms of the hybrid material formation. At TMA exposures of 60 °C, the mass of the polymer fiber increased by ∼55 wt%, whereas exposures at 150 °C were limited to ∼25 wt% infiltration. Photoluminescence analysis of PET after TMA infiltration shows an intensity increase of up to ∼13x and an increase in red shift with increasing infiltration temperature, attributed to the variations in the reaction mechanism to form the hybrid modification observed through the spectroscopy analysis.

We analyze the interplay between anomalous transport and conversion reaction kinetics in mesoporous materials functionalized with catalytic groups. Of primary interest is functionalized mesoporous silica containing an array of linear pores with diameters tunable from 2-10 nm, although functionalization can produce smaller effective diameters, d. For d < 2 nm, transport and specifically passing of reactant and product species within the pores can be strongly inhibited (single-file diffusion). The distribution of catalytic groups can also vary depending on the synthesis approach. We apply statistical mechanical modeling (utilizing spatially discrete stochastic lattice-gas models) to explore the dependence of reactivity on the extent of inhibition of passing of species within the pore, as well as on the distribution of catalytic sites.

Fully dense and net-shaped silicon carbide monoliths were produced by liquid silicon infiltration of carbon preforms with engineered bulk density, median pore diameter, and chemical reactivity derived from carbonization of crystalline cellulose and phenolic resin blends. The ideal carbon bulk density and minimum median pore diameter for successful formation of fully dense silicon carbide by liquid silicon infiltration are 0.964 g cm−3 and approximately 1 μm. By blending crystalline cellulose and phenolic resin in various mass ratios as carbon precursors, we were able to adjust the bulk density, median pore diameter, and overall chemical reactivity of the carbon preforms produced. The liquid silicon infiltration reactions were performed in a graphite element furnace at temperatures between 1414 and 1900 °C and under argon pressures of 1550, 760, and 0.5 Torr for periods of 10, 15, 30, 60, 120, and 300 min. Examination of the results indicated that the ideal carbon preform was produced from the crystalline cellulose and phenolic resin blend of 6:4 mass ratio. This carbon preform has a bulk density of 0.7910 g cm−3, an actual density of 2.1911 g cm−3, median pore diameter of 1.45 μm, and specific surface area of 644.75 m2 g−1. The ideal liquid silicon infiltration reaction conditions were identified as 1800 °C, 0.5 Torr, and 120 min. The optimum reaction product has a bulk density of 2.9566 g cm−3, greater than 91% of that of pure β–SiC, with a β–SiC volume fraction of approximately 82.5%.

Highly porous carbon-doped anatase was produced by a simple and time-saving method. The product was prepared by using sea wool sponges and a titanium-contained organic solution. The intermediate product was pyrolyzed sponges coated with amorphous anatase. When further annealed, the final product was an entirely carbon – anatase product with the original structure of sea wool sponges. The struts in the carbon – anatase product were hollow with wall thickness less than 300 nm. Cathodoluminescence measurement showed that this C-TiO2 product was sensitive to visible light.

The infiltration behavior of compacts of SiC particles in two surface conditions, as-received and thermally oxidized, was investigated by using pure Al and Al-12wt%Si as infiltrating metals. Analysis of the threshold pressure for infiltration revealed that the process is governed by the same contact angle for all different systems, no matter the metal or particle condition. This leads to the conclusion that oxidation does not modify the wetting characteristics of the particles, most probably because they are already covered by a thin native oxide layer that remains unaltered in processing routes involving short contact times and low temperatures, such as actual conditions of pressure infiltration at 700 °C.

In a hydrophobic zeolite, the infiltration and defiltration of water can be controlled by adjusting external pressure, and therefore the system behaves as a “liquid spring.” Since the hysteresis of sorption isotherm is negligible and the working pressure is thermally controllable, volume memory devices can be developed based on this phenomenon. With the addition of sodium chloride, both infiltration and defiltration pressures increase, which should be attributed to the cation exchange. The temperature sensitivity of the system increases with the electrolyte concentration, beneficial to improving the output energy density.

Superconducting MgB2 wires, of different diameter and length, have been produced by the reactive Liquid Mg Infiltration process, also implemented with the addition of extra Mg, to completely fill the internal hole created from the normal infiltration process. The actual wires have an Iron external lining and the metallic Mg internally added has a twofold effect: to avoid Mg deficiency during the reaction and to increase the quenching resistance of the wire. The superconducting characteristics of the wires have been measured either at the liquid He and at the liquid Ne temperatures, on small samples cut from meter long wires. The typical critical current density in self field, at 27.1 K, is about 1000 A/mm2, a value of interest for many power applications. The extension of the manufacturing process to longer wire will be discussed as well as the effect of the metallic lining of the wires on the contact resistance and on the current injection length.

The chemical composition of groundwater surrounding a high level radioactive waste re-pository is of importance to many factors that affect repository performance. The geochemical characteristics of Swedish groundwater systems are governed by successive mixing events be-tween several end-member waters during their paleogeographical evolution. An approach is pro-posed here to investigate the spatial and temporal evolution of groundwater geochemical condi-tions by coupling hydrogeological and geochemical models in a sequential way.

The procedure combines hydrogeological results by others of a discrete fracture net-work using CONNECTFLOW with a mixing and reaction-path simulation using PHREEQC. The hydrological results contain mixing proportions of four reference waters (a deep brine, gla-cial meltwater, marine water, and meteoric infiltration) at each time step and at every node of the 3D model domain. In this work mixing fractions are fed into PHREEQC using software devel-oped to build formatted input files and to extract the information from output files for subsequent plotting and analysis. The geochemical calculations included both chemical mixing and equilib-rium reactions with selected minerals: calcite, chalcedony and an Fe(III) oxyhydroxide.

Some results for the Forsmark site, about 170 km north of Stockholm, Sweden, are graphi-cally presented. Cross sections, where each node is color-coded with respect to an important variable (pH, Eh or concentrations of main elements), are used to visualize the future evolution of the site. Sensitivity analyses were made to evaluate the effects of the different reactions and/or assumptions. The proposed methodology has proved useful for evaluating the future geochemical evolution of the repository sites and to increase the confidence in the site descriptions.