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The ability of bulk glass and fibers to react in aqueous solution, with organic polymers and coupling agents, depends on the surface charge, reactivity, and adsorption properties of the glass surface, i.e. the character and density of surface -OH groups, whereas glass and fiber chemical stability and biosolubility depend on the resistance to dissolution. If glass dissolution products are accumulated in a media, they can change the surface properties by specific adsorption. We determined the -OH surface concentration, reactivity, adsorption, and dissolution properties of aluminosilicate glasses containing various modifiers and compared the results with the behavior of complex mineral wool fibers. Using proton consumption and element release from batch surface titration experiments, over the range 5pH10, surface -OH adsorption properties were modeled with the FITEQL program. During titration, network modifiers in the glass subsurface are preferentially replaced by protons, resulting in cation accumulation in the solution and formation of a leached layer enriched with Si on the solid. The behavior of Al was different. At 5pH9, only very small amounts of Al were found in the leachates, which can be explained by almost complete Al adsorption as stable surface complexes, i.e.XOAl(OH)

Materials made of synthetic vitreous mineral fibers, such as stone wool, are widely used in construction, in functional composites and as thermal and acoustic insulation. Chemical stability is an important parameter in assessing long term durability of the products. Stability is determined by fiber resistivity to dissolution, where the controlling parameters are solid surface area to solution volume ratio (S/V), pH and composition of the fibers and organic compounds used as binders. We investigated stone wool dissolution under flow through conditions, far from equilibrium, at pH range of 2 to 13, as well as under batch conditions, close to equilibrium, for up to 28 days, where S/V ranged from 100 to 10000 m−1. The dissolution rate of stone wool shows minimum at pH 8.5 and increases significantly at pH < 4.5 and pH > 12. In close to equilibrium conditions, S/V defines the steady state concentration for the leached components. Decreased dissolution rate could result from evolution of a surface leached layer or the formation of secondary surface phases or both. We suggested three dissolution rate controlling mechanisms, which depend on pH. That is, dissolution is controlled by: a SiO2 rich surface layer at pH < 4.5; by adsorption of an Al and Al-Si mixed surface layer at 5 < pH < 11 and by divalent cation adsorption and formation of secondary phases (silicates, hydroxides) at pH ∼ 13. The organic compounds, used to treat the stone wool fibers during manufacture, had no influence on their dissolution properties.

Glass fibers of various forms, continuous and discontinuous, have been widely used as reinforcements of plastic composites or standalone, such as thermal insulations, in general industry, construction, transportation, consumer goods, aerospace, and defense applications. The fiber glass production technology and capacity have been growing with a rapid rate since the mid-1990s. The first part of this chapter discusses many essential segments of continuous glass fiber, covering history of its development, property-based classification, production-related topics, including raw materials, batch-to-melt conversion, fiber drawing and sizing functionality, an integrate part of the glass fiber products. Useable fiber glass strength is one of the important product specifications, which will be detailed. Fiber glass formulation design meeting specific requirements, both application and processing, is introduced in conjunction with composition–structure–property statistical modeling approach. Global commercial market segments and key glass fiber producers are also covered. The second part of this chapter discusses another commercial fiber type, mineral wool fiber. The main types of mineral wool products have been used among many applications as insulation material to improve energy efficiency of existing and new buildings. In focus is the two dominating mineral wool product types, i.e., stone and glass wool. The products and hence, fibers are characterized by having a significant different chemical compositional range resulting in marked different fiber forming technologies i.e., external and internal centrifugation technique, respectively. In focus is as well the mineral wool fiber materials itself including fiber characteristic and the fibers low biopersistence and durability. Illustrated is the mineral wool production technology and the achieved thermal properties of a mineral wool product. The global mineral wool market is discussed including presentation of the key industrial players.

The intrinsically disordered protein α-synuclein (aSN) forms insoluble aggregates in the brains of Parkinson's disease (PD) patients. Cytotoxicity is attributed to a soluble aSN oligomeric species that permeabilizes membranes significantly more than monomers and fibrils. In humans, the A53T mutation induces early onset PD and increases the level of aSN oligomerization and fibrillation propensity, but Thr53 occurs naturally in aSNs of most animals. We compared aSNs from elephant, bowhead whale, and pig with human aSN. While all three animal aSNs showed significantly weakened fibrillation, elephant aSN formed much more oligomer, and pig aSN much less, than human aSN did. However, all animal aSN oligomers showed weakened permeabilization toward anionic lipid vesicles, indicative of decreased cytotoxicity. These animal aSNs share three substitutions compared to human aSN: A53T, G68E, and V95G. We analyzed aggregation and membrane binding of all eight mutants combining these three mutations. While the G68E mutation is particularly important in weakening fibrillation and possible toxicity, the strongest effect is seen when all three mutations are present. Thus, a small number of mutations can significantly decrease aSN toxicity.

Stone wool is a widely used material for building insulation, to provide thermal comfort along with fire stability and acoustic comfort for all types of buildings. Stone wool waste generated either during production or during renovation or demolition of buildings can be recycled back into the stone wool melt production. This study investigates and compares the thermal response and melting behaviour of a conventional stone wool charge and stone wool waste. The study combines differential scanning calorimetry (DSC), hot stage microscopy (HSM) and X-ray diffraction (XRD). DSC reveals that the conventional charge and stone wool waste have fundamentally different thermal responses, where the charge experiences gas release, phase transition and melting of the individual raw materials. The stone wool waste experiences glass transition, crystallization and finally melting. Both DSC and HSM measurements indicates that the wool waste initiates melting at a lower temperature than the conventional charge. Also DSC measurements show that the wool waste requires less energy for heating and melting than the conventional charge, making stone wool waste recycling desirable both for environmental and for process purposes.

Viscosity at the liquidus temperature (TL), ηL, is a critical parameter for the design of new glasses, particularly for industrial glass production where crystallization must be suppressed. However, a direct viscometric determination of ηL for a glass-forming system is difficult due to crystallization. Here we propose an alternative approach for determining ηL through differential scanning calorimetry (DSC). Specifically, DSC is used to measure both the viscosity curve and liquidus temperature of a glass-forming system and then derive its ηL value. The ηL values determined using DSC are found to be in excellent agreement with those measured through viscometry. The DSC approach is applicable to various glass-forming systems covering a wide range of fragilities and ηL values spanning over five orders of magnitude. Other advantages of this approach are its accuracy and small sample requirements.

Mineral wool products, composed of stone wool fibers and organic binder, are used in many construction applications. Among all their beneficial properties, the most important requirement is safety for human health, such as when fibers are inhaled. For determining long-term toxicity, biosolubility and biopersistence studies in vitro and in vivo are essential. In vitro fiber dissolution rate, which depends on the medium, fiber composition, and the surface available for dissolution, is a key parameter in determining biopersistence of the material in vivo. We investigated how organic binder (phenol-urea-formaldehyde), which can partially shield fiber surfaces from the solution, influences fiber dissolution kinetics in synthetic lung fluid (modified Gamble's solution) at pH 4.5 and temperature 37 °C, in vitro. Dissolution experiments were made in batch and continuous flow using stone wool fibers with typical insulation product binder amounts (0-6 wt %), applied by the standard industrial process. Dissolution rates were determined from element concentrations in the reacted solution, and changes in fiber surface composition and morphology were monitored. Stone wool fiber dissolution was close to stoichiometric and was similar, whether or not the material contained binder. The high dissolution rate (508 ng of fiber/cm2/h) is explained by Al and Fe complexing agents, that is, citrate and tartrate, in the synthetic lung fluid. The organic binder mainly forms micrometer-sized discrete droplets on the fiber surfaces rather than a homogeneous thick coating. During in vitro tests, fibers with organic binder preferentially dissolved in the areas free of binder, forming cavities, whereas the untreated fibers dissolved homogeneously. Propagation of cavities undermined the binder droplets, leading to complete fiber dissolution. Thus, presence of organic binder on stone wool fibers, produced by the standard industrial process, had no measurable effect on dissolution rate in synthetic lung fluid containing Al and Fe complexing agents.

Glass composite materials were investigated for use as a seal between Fe78Cr22 steel interconnects and cell components. Additions of MgO-filler to the sodium aluminosilicate (NAS) base glass increased the coefficient of thermal expansion of the composite to ∼12 ppm and provided a sufficient match between the components to allow for thermal cycling of the interfaces. The optimisation of composite seals with long-term compliancy showed promising results in terms of being able to control both the bonding strength and interface reactivity between metal and glass. The reactivity increased with temperature and protection of the surface by pre-oxidation did not alter the picture. Etching the metal surfaces in combination with application of Mn-, Co-, or Ni-oxide coatings reduced the metal–glass interactions and for the Ni- and Co-oxide coatings facilitated an excellent bond and gradual changing interface between the glass and metal. Samples were tested in model experiments and performance tested in multi-cell stacks. Both pure NAS glass and NAS/MgO composite material developed gas tight sealing performance, when sealed at 950 °C and showed low, constant levels of leakage throughout multiple thermal cyclings after more than 5000 h run time in stack testing.

The thermal expansivities of 10 compositions from within the anorthite–wollastonite–gehlenite (An–Wo–Geh) compatibility triangle have been investigated using a combination of calorimetry and dilatometry on the glassy and liquid samples. The volumes at room temperature were derived from densities measured using the Archimedean buoyancy method. For each sample, density was measured at 298 K using glass that had a cooling-heating history of 10–10 K min−1. The thermal expansion coefficient of the glass from 298 K to the glass transition interval was measured by a dilatometer and the heat capacity was measured using a differential scanning calorimeter from 298 to 1135 K. The thermal expansion coefficient and the heat flow were determined at a heating rate of 10 K min−1 on glasses which were previously cooled at 10 K min−1. Supercooled liquid density, molar volume and molar thermal expansivities were indirectly determined by combining differential scanning calorimetric and dilatometric measurements assuming that the kinetics of enthalpy and shear relaxation are equivalent. The data obtained on supercooled liquids were compared to high-temperature predictions from the models of (Lange, R.A., Carmichael, I.S.E., 1987. Densities of Na2O–K2O–CaO–MgO–FeO–Fe2O3–Al2O3–TiO2–SiO2 liquids: New measurements and derived partial molar properties. Geochim. Cosmochim. Acta 51, 2931–2946; Courtial, P., Dingwell, D.B., 1995. Nonlinear composition dependence of molar volume of melts in the CaO–Al2O3–SiO2 system. Geochim. Cosmochim. Acta 59 (18), 3685–3695; Lange, R.A., 1997. A revised model for the density and thermal expansivity of K2O–Na2O–CaO–MgO–Al2O3–SiO2 liquids from 700 to 1900 K: extension to crustal magmatic temperatures. Contrib. Mineral. Petrol. 130, 1–11). The best linear fit combines the supercooled liquid data presented in this study and the high temperature data calculated using the Courtial and Dingwell (1995) model. This dilatometric/calorimetric method of determining supercooled liquid molar thermal expansivity greatly increases the temperature range accessible for thermal expansion. It represents a substantial increase in precision and understanding of the thermodynamics of calcium aluminosilicate melts. This enhanced precision demonstrates clearly the temperature independence of the melt expansions in the An–Wo–Geh system. This contrasts strongly with observations for neighboring system such as anorthite–diopside and raises the question of the compositional/structural origins of temperature dependence of thermal expansivity in multicomponent silicate melts.

A novel instrument for high temperature thermogravimetric measurements in atmospheres containing high water vapour contents was developed in a collaboration between Netzsch and Riso National Laboratory. The development of the instrument was initiated to facilitate the investigation of high temperature corrosion of steels in humidified atmospheres. The instrument consists of a standard thermal analyser unit, including a new water vapour furnace, balance and sample carrier. The design of the instrument is discussed and thermogravimetric measurements on a Fe78Cr22 steel are presented.

For melts within the compatibility triangle anorthite–wollastonite–gehlenite (An–Wo–Geh) (CaAl2Si2O8–CaSiO3–Ca2Al2SiO7), the relationships between the chemical composition, the melt structure, and the rheological and thermodynamic properties are studied for each of the boundary lines, i.e. the An–Wo, Wo–Geh and Geh–An join. The influences of the degree of polymerization of the structural network and the amount of Al–O–Al linkages on the fragility and the configurational entropy of the melts are studied along the boundary lines. For the An–Wo join, the degree of polymerization dominates the responses of both fragility and configurational entropy to compositional variations. For the Wo–Geh and Geh–An joins, the amount of the Al–O–Al linkages dominates those responses. It is found that the depolymerization of the structural network and the formation of Al–O–Al linkages increase the fragility of the melt and the degree of structural disordering.

Glass ceramic and glass composite were investigated for use as sealant between SOFC components and materials, metallic interconnect of Fe 78 Cr 22 steels and anode supported Ni/YSZ-based fuel cell. An alkaline earth aluminoborosilicate glass worked as the base glass with magnesium oxide particles added as filler to the composite. Thin sealant layers (60-120 μm) of the alkaline earth aluminoborosilicate glass ceramic formed discontinuous sealant layers with good bonding to the fuel cell materials, but with only moderate bonding to the interconnect materials, regardless of type and bonding temperature. The glass composite (31 vol% MgO filler) prepared to match the coefficient of thermal expansion (CTE) of the cell and interconnect materials, CTE ∼13 x 10 -6 K -1 , showed excellent bonding to both the fuel cell and the interconnect, Crofer 22APU, at anode and cathode conditions and the bonding temperatures 850°C and 950°C. Bonding to the other interconnect, Sandvik 0YC44, was not as good and after thermal cycling, even cooling of the interface, cracks separated seal and interconnect materials with the presence of a barium chromate layer adjacent to the interconnect indicating poor wetting during heat-up sequences. Excessive corrosion reactions at the three-phase boundary between air, sealant and interconnect were observed and may limit the industrial potential of the sealant. The glass composite seal was tested gas tight after sealing fuel cell and interconnect at 850°C in a short stack test showing encouraging results for sealing behaviour and moderate thermal cycling of the interfaces.

Glass-based sealants have been developed with emphasis on filler material and surface treatment of the sealing components in order to optimise their mechanical and functional behaviour during the initial sealing process as well as during thermal cycling of the SOFC-stack after exposure to operating conditions. The bonding strength and microstructure of the interfaces between composite seals and interconnect materials were investigated as a function of surface treatment of the sealing surfaces, glass matrix composition, sealing pressure and temperature. The initial sealing performance and resistance to thermal cycling were then investigated on selected combinations of materials after ageing. Strongest bonding between sodium aluminosilicate glass composite and steel surfaces was obtained for sealing at 850°C. For the strongest interface, having shear strength of 2.35 MPa, rupture occurred in the glass matrix, meaning that the glass-steel interfaces are, in this case, even stronger. Application of transition metal oxide coatings on etched surfaces of Crofer 22APU steel showed a significant improvement in the development of a seamless transition zone between metal and glass, whereas the same coatings on a sanded surface showed no influence on the bonding strength, which on the other hand were all recorded at a fairly high level, only 15-20% less than the 2.35 MPa seen for the glass. Ageing and thermal cycling of sealed samples did not deteriorate the recorded strength.

Glassy seals are used for short term testing, less than 3-4000 hours, of SOFC materials and components in the laboratory. A composite glass seal where Magnesia particles have been suspended in a Sodium Aluminosilicate glass matrix was investigated in order to evaluate the sealing performance towards metallic interconnects of Fe22Cr-steel. Seal compressibility limited the amount of particles, which could be suspended, thus limiting the range of thermal expansion (

The relationships between the chemical composition and the derivative rheological and thermodynamic values have been determined for two melt series in the anorthite–wollastonite–gehlenite (An–Wo–Geh) compatibility triangle. The melt series have 0.5 and 1 non-bridging oxygens per tetrahedrally coordinated cation (NBO/T), respectively. The influences of the ratio Si/(Si + AlCa 1/2 ) and NBO/T on the fragility and the configurational entropy at T g are evaluated. Linear dependencies of the viscosity, the glass transition temperature and the fragility on the ratio Si/(Si + AlCa 1/2 ) are found for the two melt series. A crossover in the viscosity–temperature relationship is observed for both series, i.e. an inverse compositional dependence of viscosity in the high and low viscous range. The crossover presumably reflects different responses of the adjustment of melt structure to the substitution of Al 3+ + 1/2Ca 2+ for Si 4+ in the low versus the high viscous ranges. The crossover shifts to higher temperature with increasing NBO/T.

Two melt series, i.e. the MgO–CaO–Al2O3–SiO2 (MCAS) and the Fe2O3–MgO–CaO–Al2O3–SiO2 (FMCAS) series, were investigated with respect to rheological and thermodynamic properties. The results show that substituting MgO for CaO, and Fe2O3 for MgO has a strong influence on viscosity, fragility, configurational entropy and glass transition temperature (Tg) of the glasses. For the MCAS melt series, the effect of the ideal (Ca, Mg) mixing (so-called mixed earth alkaline effect) is seen, and its origin is analyzed. When Fe2O3 is introduced into the MCAS system, both the viscosity and the Tg decrease. The network is weakened by substituting Fe2O3 for MgO. The fragility of the melt decreases with substitution of Fe2O3 for MgO, until it remains unchanged during further substitution. Hence, there is a critical Fe2O3/MgO ratio, above which the fragility is not sensitive to the total amount of Fe2O3 in the FMCAS system.

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