Mechanical reliability such as strength and brittleness is of great interest for application of brittle materials, i.e. glasses and glass fibres. In this paper we study the fracture behaviour and the tensile strength of glass wool fibres (GWFs) of both basalt and E-glass compositions, which play an important role in both transportation and application of GWFs (as insulation material). GWFs are tested in uniaxial tension. The surfaces of the fractured fibres are imaged using scanning electron microscopy. Three main types of fracture surfaces produced in tensile stress are observed, all of which include fracture mirror, mist and hackle features comparable to fracture surfaces of bulk glass and continuous fibres. The three types are: a) surface without visible origin; b) surface with visible origin; c) surfaces originated from internal pores. The relations between the fracture mirror size and the mechanical strength shown for bulk glass and continuous glass fibres are also valid for GWFs. Relation between the fractographic observations and the strength Weibull distributions are discussed in relation to chemical composition and homogeneity.

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Pure silica is commonly used as a calibration material for nano-indentation as it can be assumed, for the conventionally studied indentation depths, that the surface hydration layer can be ignored. However for very low load indentations this assumption cannot be made. To gain some insight into the properties of such gel layers nano-indentation studies on the hydration layers on three silicate glasses that hydrate more and less slowly are performed. With the less durable glasses (a soda-silica composition and a high soda, low lime soda-lime-silica composition) the evolution of the mechanical properties of the hydration layers with time can be readily followed. The limiting stiffness values obtained for very low load indentation on pure silica are used to assess the potential effect of such a hydration layer on pure silica on nano-indentation calibration using pure silica.

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An in situ ultrasonic echography technique is used to follow the changes in the elastic moduli (Young's modulus and shear modulus) from room temperature to complete crystallisation temperature (~900 K) of a ZrCuAlNi bulk metallic glass. Elastic moduli changes allow to probe the structural transformations of the alloy below and above the glass transition as well as the crystallisation stages. Of peculiar interest is the unusual decrease in Poisson's ratio.

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The viscosity-temperature relationships for metaphosphate glass and polystyrene in the wide-temperature range, including below the glass transition temperature T_g, obtained by us, were analyzed using the Adam-Gibbs theory. The results showed that the glass transition is a non-equilibrium phase transition from the Vogel-Tammann-Fulcher (VTF) state to the Arrhenius state occurring at T_g. The Arrhenius curves below T_g show different slopes with varying activation energies owing to the fictive temperatures T_f characterizing the structural states of the glasses. To explain this result from the microscopic viewpoint, a model of an intermediate range order (IRO) is proposed. We also propose that the glass transition is due to a self-organization of the IROs, a few nanometers in size, in the glass state.

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Transparent surface crystallized glasses consisting of c-axis oriented nonlinear optical Ba₂TiGe₂O₈ crystalline layers (~10 μm) at the surface of 40BaO·20TiO₂·40GeO₂ glass are prepared, and their deformation behaviors are examined from the load/unload displacement curves obtained with the Vickers nanoindentation technique. It is found that the surface crystalline layers deform easily in small loadings during Vickers nanoindentations in comparison with the precursor glass with a homogeneous random glass structure. The surface crystalline layers subjected to the penetration depth of h = 0.5 μm show a large elastic recovery of ~70% compared with that (49%) in the precursor glass. The sliding (displacement) of about 0.02 μm is observed immediately after the stop of the loading with a loading speed of 5 μm/s in the surface crystallized samples. The present study suggests that the deformation behaviors of the surface Ba₂TiGe₂O₈ crystalline layers in the crystallized glass might be closely related to the assemblage state of highly oriented crystals, in particular, the bonding (i.e., the degree of the adhesion ) among c-axis oriented crystals might be weak.

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Permanent deformation of glass under a sharp diamond indenter can be divided into two modes; plastic (or shear) flow and densification. The former is a volume-conservative deformation process, and the latter includes volume contraction. It is very important to recognize how much these two processes contribute to the formation of indentation impression in order to understand permanent deformation of glass. In this study, using an atomic force microscope (AFM), annealing recovery of indentation impression in soda-lime glass was studied under several annealing conditions. After annealing, large shrinkage of Vickers indentation was observed and it was attributed to relaxation of densified volume under the indenter. The recovery ratio of indentation volume by annealing increased up to 71% with increasing the annealing temperature to the glass transition temperature (539°C). Relaxation of densified volume was observed even at a low annealing temperature (214°C). It is suggested that the recovered region by annealing at a given temperature is determined from the microscopic glass density which is affected by the pressure distribution under the Vickers indenter.

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Quantitative measurements were made in silica glass of highly graded stress fields, as they developed: (i) in the K-dominated zone ahead of the tip of a median-type indentation micro-crack; and, (ii) at a silicon-silica interface of a metal-oxide semiconductor (MOS) device. Stress fields could be visualized on a microscopic scale using a field-emission scanning electron microscope (FE-SEM) equipped with a spectrally resolved cathodoluminescence (CL) device, according to piezo-spectroscopic (PS) assessments. The peculiarity of this newly proposed PS assessment resides in the fact that the performed CL/PS analysis exploited a peculiar luminescence emitted by optically active oxygen point defects in silica glass.

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Glasses having a low softening temperature are desired for compression molding techniques in order to lengthen the mold life. The final goal of this research is to obtain glasses, which are suitable for the precise molding in order to fabricate micro- to submicro-structures on the glass surfaces, utilizing the ion-exchange technique, which lowers the softening temperature of only the surface regions of the glasses. We examined variations in optical and thermal properties of a soda-lime silicate glass after ion-exchange in AgNO₃-NaNO₃ molten salts under various conditions. The glass transition and softening temperatures were lowered after the ion-exchange by 80 K and 70 K, respectively. Molding tests were demonstrated for the ion-exchanged glasses using a glassy carbon mold having a one-dimensional periodical structure of 500 nm in frequency and 350 nm in depth within the area of 6 × 6 mm². It was found that the structure was successfully transferred on a part of the surface of the ion-exchanged glass at a lower temperature than that for the glass before ion-exchange.

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The atomic scale deformation behavior of SiO₂ and Na₂O-SiO₂ glasses is studied by Molecular Dynamics (MD) simulation methods. First, the pressure exerted on the simulation box is varied and the effects of isotropic compression and expansion imposed on both glasses are investigated. The SiO₂ glass shows the well-known densification under a compression pressure of 7 GPa or above. In contrast, no densification is observed for the Na₂O-SiO₂ glass. Next, the shape of the simulation box is varied and the effects of shear deformation exerted on both glasses are investigated. In the case of the SiO₂ glass, the shear deformation brings about an increase in shear stress up to over 4 GPa at first; however, further shearing of the simulation cell results in a decrease in shear stress, accompanied with densification. On the other hand, in the case of Na₂O-SiO₂ glass, shear stress rises up to about 1.5 GPa at first and the further tilting keeps almost the same value of shear stress, without densification. These calculated results suggest that two different behaviors of atomic scale deformation exist. The exchange of Si-O bonds is the main event occurring in SiO₂ glass during deformation. This phenomenon leads to the densification. In contrast, in the case of Na₂O-SiO₂ glass, mobile sodium ions can accommodate their positions to relieve stress so that the breaking of Si-O bonds is considerably reduced. This phenomenon displays a behavior similar to plastic flow before fracture appears.

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The deformation and fracture of a soda-lime-silica glass were investigated under tension by molecular dynamics simulation. The process of the deformation consisted of elastic deformation, flow, and expansion accompanied with flow in the order before the glass fractured. The main structural change on each deformation was the expansion of Si-O-(Al, Si) angle, change of network rings, and growth of cavity. The cavities were generated in the region where non-bridging oxygen ions clustered and grew up in the region where Ca ions clustered in addition to the clustered non-bridging oxygen ions. The fracture time became shorter and the fracture strain and volume decreased with increasing tension.

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Stress relaxation and viscous flow of Ge_xSe_1-x and TAS chalcogenide glasses were studied using the "bending method". Inadequacy of common models or functions to describe relaxation process of inorganic glasses were proved and the origin of an unexpected relaxation behaviour is discussed. Even if most part of the stress relaxes for short period (10 to 20 days), a significant part still remains (from 5 to 33%) after over one year. A linear viscoelastic behaviour has been demonstrated in the sense of an independence of the relaxation function to the stress level. However, the apparent viscosity seems to increase of almost one order of magnitude in only one month (from 5 10¹⁵ to 3 10¹⁶ Pa·s for TAS fibers) independently of strain or stress level, that is characteristic of glass structural changes.

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An experiment on surface coating of ceramic tiles with titanium dioxide (TiO₂) pigmented acrylate formulations have been done using UV-curing system. A coating formulation is the mixture of epoxy acrylate resin (80 mass% aromatic epoxy acrylate in 20 mass% hexandiol diacrylate), tripropylene glycol diacrylate (TPGDA) monomer, titanium dioxide pigment and photoinitiator of 2,2-dimethyl-2-hydroxy acetophenone (Darocur 1173). Coating on ceramics was carried out with a wire bar coater to get film thickness of around 150 μm. UV-curing was conducted by using 80 Watt/cm intensity UV-source at a fixed photoinitiator concentration and exposure time (represented by conveyor speed). Concentrations of titanium dioxide and TPGDA in the coating formulation were varied to evaluate their effect on physical, mechanical and chemical properties of cured films. A fixed photoinitiator concentration and conveyor speed used in the experiment were determined after evaluating the pendulum hardness of cured films in a sequence of experiments. Parameters observed were viscosity, contact angle, pendulum hardness, gloss, adhesion, color value, and chemical, solvent and stain resistance.

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The structure of sodium lead apatite Na₂Pb₈(PO₄)₆ has been determined using single-crystal X-ray diffraction. Crystal data are: hexagonal, space group P6₃/m, Z = 1, a = 972.1(4) pm, c = 718.6(5) pm, V = 588.1(5) 10⁶ pm³, and R = 0.038. The result of charge distribution analysis confirmed the structural hypotheses.
In the Raman spectrum, the two bands observed at 935 cm^-1 and at 966 cm^-1, have been attributed to the A_g-E_2g splitting, in the hexagonal C_6h symmetry, of the nondegenerate symmetric stretching v₁(PO₄). Translational modes of Pb²⁺ have been identified at 44, 53, 56, 76 and 78 cm^-1. The results of ³¹P and ²³Na magic angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopies confirmed the structural hypotheses.

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Voids of 50-100 μm in size may be generated adjacent to the Cu conductor when a Cu/glass ceramic multilayer wiring substrate is co-fired. Carbon residue derived from the binder (ethyl-cellulose) in the Cu paste is related to the generation of such voids. The main components of the gas that generates a void are H₂O and CO. In addition, Cr-Fe-O particles from Cr and Fe impurities in the Cu powder of the Cu paste are present in the void. The mechanism for generation of a void is presumed to be that carbon residue derived from the binder in Cu paste is oxidized by H₂O introduced at the binder burnout stage, and as a result, H₂ and CO are generated (water gas shift reaction). Cr₂O₃ and Fe₂O₃ function as catalysts for a reaction that becomes a trigger for the water gas shift reaction. CuOH can be formed on the surface of the Cu conductor by reaction with the OH generated from this trigger reaction. H₂O is generated by the dehydration of CuOH on the surface of the Cu conductor during the sintering stage. When the Cr and Fe content in the Cu powder of the Cu paste, the carbon residue derived from binder in the Cu paste, and the amount of H₂O introduced when the binder is burnt out, were decreased according to the derived void generation mechanism, the number of the voids bounded on the Cu conductor was decreased.

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Binary SnO-P₂O₅ (SP) glasses with 52-72 SnO mol% were examined. Glass transition temperature, density, refractive index and absorption edge were studied for transparent SP glasses. The structure of SP glasses was evaluated by FT/IR and Raman spectroscopy. The water durability was investigated by weight loss and Raman spectroscopy for SP glass samples immersed in distilled water at 30-70°C. Raman spectra indicated in the immersion test that Q¹ units form and Q² units decrease as a result of water attack upon the phosphate chains with increasing immersion time in 62SnO·38P₂O₅ glass and no structural change was observed in 72SnO·28P₂O₅ glass. The relationship between the properties and glass structure with chemical bonding is discussed.

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