Effects of Ion Exchange on the Mechanical Properties of Basaltic Glass Fibers

Lezzi P.J., Seaman J.H., Tomozawa M.

Earlier, a new glass strengthening method was demonstrated using silica glass fiber. The method involved heat-treatment of a glass while held under a sub-critical tensile stress. The added strength was attributed to the formation of a compressive stress layer on the surface created by a surface stress relaxation process. This new glass strengthening method does not require glass of finite thickness, as in tempering, or glass containing alkali ions, as in ion-exchange. The same method was applied to E-glass fibers by treating the fibers under 1 and 2 GPa stresses at 200 °C for 60 s in air and a strength increase of ~ 0.6 GPa was achieved. The extent of the surface residual stress formation was estimated from the permanent bending kinetics of glass fibers heated under bending stresses and released. In the present work, the origin of the strengthening is attributed to the surface compressive stress rather than an anisotropic structure of the glass. The stability of the residual surface stress produced was estimated by measuring the kinetics of unbending of bent fibers at 325–425 °C in air. The relaxation time of the surface stress release at room temperature in air was estimated to be at least 1 to 3 years. • E-glass fiber becomes stronger when heated while subjected to a tensile stress. • The fiber subjected to tensile stress acquires a surface residual compressive stress. • The residual stress is produced by surface stress relaxation promoted by water vapor.

Manylov M.S., Gutnikov S.I., Pokholok K.V., Lazoryak B.I., Lipatov Y.V.

As found by differential thermal analysis, X-ray diffraction and Mossbauer spectroscopy, the heat treatment of basalt glass fibers in air leads to complete iron oxidation and the bulk growth of superparamagnetic magnesioferrite particles which act as nucleation sites for pyroxene crystallization.

Lezzi P.J., Xiao Q.R., Tomozawa M., Blanchet T.A., Kurkjian C.R.

Pristine silica glass fiber is well known to become mechanically weaker when heat-treated in the presence of water vapor. However, the same fiber was found to become stronger if heat-treated while held under a sub-critical tensile stress at a temperature far below the glass transition temperature. The added strength of the stress-treated fiber was nearly equal to the applied tensile stress. This added strength was attributed to the formation of a compressive stress layer on the surface of the glass, created by a surface stress relaxation process that occurred while being held under the tensile stress. The presence of the surface compressive stress was confirmed by observing the bending of the fiber when 1) a tensile-stressed fiber was sliced and 2) a bending-stressed fiber was released from the stress. In the present paper we demonstrate that even though heat-treatment of a silica glass fiber in water vapor weakens the glass, a tensile stress application during the heat-treatment can increase the strength of silica glass fibers. Silica glass fibers with estimated strengths of ~ 7–8 GPa were produced, exceeding that of other fibers previously reported to have a maximum strength of ~ 5.5 GPa at room temperature in air. This new glass strengthening method does not require glass to be of a minimum thickness, as in tempering, or a glass containing alkali ions, as in ion-exchange.

Leboeuf V., Blondeau J., De Sousa Meneses D., Véron O.

The aim of this work is to obtain information on structural modification of glass during potassium ionic exchange for mechanical reinforcement. These modifications are evaluated by two characterization methods; scanning electronic microscopy and Fourier transform infrared spectroscopy. The SEM study gives the potassium concentration profile, allows the kinetics of ionic exchange to be observed and gives access to the interdiffusion coefficient with a good concordance between theoretical and experimental concentration profiles. We have verified that the exchange is done between Na+ and K+ ions. We have coupled this SEM result to infrared spectroscopy measurements in middle and far infrared ranges and have proved that infrared spectroscopy allows the access of the structural evolution of glass near the surface after chemical tempering. The evolution of the stretching vibration of Qn modes, between 850 and 1250 cm− 1, shows a depolymerization of the silica network. The Gaussian positions of Qn modes evolve with the exchange time and prove that there is an increase in the rigidity of the silica network due to a compression state.

Gutnikov S.I., Manylov M.S., Lipatov Y.V., Lazoryak B.I., Pokholok K.V.

Basalt continuous fibers were treated in H 2 /Ar atmosphere at 650 °С and 700 °C. The 57 Fe Mössbauer spectroscopy indicated that after the treatment at 650 °C all ferric cations reduced to ferrous. Reduction at higher temperature leads to metallic iron formation. DSC and XRD data indicated that crystallization process in reduced basalt fibers carried slower. Glass transition temperature decreases after the reduction due to the increase of amount of ferrous cations, that act as modifiers. Due to Fe 2 + /Fe 3 + ratio changing spinel-like phase crystallization ability decreases. Crystallization in reduced basalt fibers starts at lower temperature. The tensile strength of reduced fibers is higher than the tensile strength of basalt continuous fibers that were annealed at the same condition in air. • Basalt continuous fibers were reduced in H 2 atmosphere. • Due to Fe 2 + /Fe 3 + ratio changing crystallization mechanism changes. • Crystallization process in the reduced basalt fibers carries slower. • The tensile strength loss of the reduced fibers is 40.4%.

Novitskii A.G., Efremov M.V.

It is shown that continuous basalt fiber can be made from unconventional rock from different countries. The main technological parameters of the continuous-fiber production from basic rocks with SiO2 content from 45 to 50% are determined. The main physical-chemical characteristics of continuous basalt fiber are studied.

Bykov V.N., Eremyashev V.E., Anfilogov V.N.

The structure of quenched aluminosilicate glasses with Na2O/Al2O3 > 1 has been studied by high-resolution nuclear magnetic resonance spectroscopy. The aluminum in the structure of the glasses is shown to be in fourfold coordination. Increasing the sodium oxide content of the glasses reduces the degree of polymerization in their structure and leads to a nonuniform nonbridging oxygen distribution over the aluminosilicate glass network. The glasses have a locally microinhomogeneous structure due to the presence of both highly polymerized aluminosilicate anion groups and relatively depolymerized silicate anions.

Lund M.D., Yue Y.

The sources of the tensile strength and fracture of both continuous glass fibers and discontinuous wool fibers are explored in terms of structural anisotropy, enthalpy relaxation, defect orientation, and surface inhomogeneities. The fibers are spun from the E-glass and the basaltic glass melts, respectively. It is revealed that axial stress plays an important role in enhancing the strength of the oxide glass fibers. The increase of axial stress leads to the increase of both the structural anisotropy and the defect (flaws, bubbles, striae, etc.) orientation, and hence the increase of the tensile strength. Besides the axial stress, the increase of the cooling rate also increases the tensile strength of the continuous fibers. These findings are further substantiated by annealing experiments on both continuous and wool fibers below Tg. The onset annealing temperature of the tensile strength decay is close to that of the anisotropy relaxation of the continuous fibers. The relative contributions of the different factors to the fiber strength are schematically scaled with the help of the sub-Tg annealing.

Varshneya A.K.

This paper reviews the progress that has been made in our understanding of the chemical strengthening of glass by ion exchange over its nearly five decades of history. Lessons learned are briefly discussed; more importantly, those which are yet to be learned are highlighted. It is recognized that, except for detailed compositional effects, the kinetics of ion interdiffusion process and the chemical strengthening technology are reasonably well understood. However, the science of stress generation and its concurrent relaxation is far from being clear despite the elegant analogy to thermal stresses invoked by Cooper. The need to understand plasticity of glass network during accommodation of a larger invading ion is emphasized. In turn, the influence of network topology on its yield strength in shear as well as hydrostatic modes is recognized. For expanded applications under extreme conditions of loading, damage evolution in chemically strengthened glass needs to be studied. Such a study is linked to our understanding of the terms “strength,”“hardness,”“toughness,” and “brittleness” of glass.

Feih S., Manatpon K., Mathys Z., Gibson A.G., Mouritz A.P.

This article presents an experimental investigation into the effects of temperature and heating time on the tensile strength and failure mechanisms of glass fibers. The loss in strength of two glass fiber types (E-glass and Advantex®, a boron-free version of E-glass) was investigated at temperatures up to 650 °C and heating times up to 2 h. The tensile properties were measured by fiber bundle testing, and the maximum strength was found to be temperature and time dependent. The higher softening point of the Advantex® fibers is reflected in superior high-temperature performance. A phenomenological model is presented for calculating the residual strength of glass fiber bundles as functions of temperature and time. The strength reduction mechanism was determined by single-fiber testing. Fracture mirror sizes on the E-glass fibers were related to the fiber strength after high-temperature treatment. Based on fracture mirror measurements, it was established that (1) the mirror constant of the glass, which reflects the network structure, does not change during heat treatment and (2) the strength degradation is a result of larger surface flaws present after heat treatment.

Deubener J., Yue Y., Bornhöft H., Ya M.

The relaxation kinetics at the glass transition and in the sub-Tg range in a calcium boro-alumosilicate glass (E-glass composition) was studied from viscosity, birefringence and calorimetric measurements to clarify the thermal dependence of structural relaxation in hyper-quenched glass fibres. A decoupling of birefringence relaxation and viscous relaxation, i.e., a large discrepancy between the activation energies for optical recovery ΔHΔn = 25 ± 4 kJ mol− 1, and viscous flow at the glass transition Eη = 399 ± 8 kJ mol− 1 is evident from fibre annealing and viscometric experiments. The decoupling ratio of ΔHΔn/Eη = 0.06 is found to be close to that of γ-relaxation (internal friction) to α-relaxation in sodium trisilicate glass when plotted in a reduced Tg/T-scaled form. In contrast to the birefringence, the enthalpy relaxation is found to be related to the isostructural dependence of viscosity. These observations imply that the thermal dependence of the optical anisotropy relaxation is related, as the alkali mobility, to local structural arrangements, whereas the enthalpy relaxation seems to be dominated by relaxation of the silicate melt network [Yue, Y.Z., Christiansen, J., de, C., Jensen, S.L., 2002. Determination of the fictive temperature for a hyperquenched glass. Chemical Physics Letters 357, 20–24], including cooperative motion of larger structural ranges.

Ya M., Deubener J., Yue Y.

Optical birefringence and calorimetric studies have been conducted with respect to structural relaxation of E-glass (a type of calcium-alumosilicate glass system) fibers. Upon fiber drawing, the liquid of E-glass is thermally hyperquenched and mechanically stretched. Hyperquenching (cooling rate >10 6 K/min) leads to higher enthalpy state of liquids, and thereby, to a higher fictive temperature than normal quenching (20 K/min), whereas stretching results in structural anisotropy of glasses, i.e., a certain degree of preferred structural orientation (stretched network) along the axial direction of the fibers, which is quantified by the optical birefringence. Simultaneous relaxation of both anisotropy and excess enthalpy (relative to the enthalpy of a glass cooled at the standard rate of 20 K/min) upon static annealing and dynamic heating is observed, both of which can be described using the Kohlrausch function. However, there is a striking difference between the birefringence and the excess enthalpy relaxations. The birefringence decays much faster than does the excess enthalpy during annealing. These observations imply that the birefringence decay results from fast relaxation of the local structure, while the enthalpy relaxation results from slow relaxation of larger domains of the network.

Gy R.

This paper presents a short overview of silicate glass strengthening by exchange of alkali ions in a molten salt, below the glass transition temperature (chemical tempering). The physics of alkali inter-diffusion is briefly explained and the main parameters of the process, which control the glass reinforcement, are reviewed. Methods for characterizing the obtained residual stress state and the strengthening are described, along with the simplified modelling of the stress build-up. The fragmentation of chemically tempered glass is discussed. The concept of engineered stress profile glass is presented, and finally, the effect of glass and salt compositions is overviewed.

Yue Y.

The glass transition temperature, T g , directly measured by differential scanning calorimetry at 10 K/min is compared with the T g indirectly determined by fitting viscosity data to a viscosity model for oxide glasses. The results show good match between the two T g values. A standard, unified approach for measuring T g is proposed. Characteristic temperatures of enthalpy relaxation in glass are defined, and the relationships between these temperatures are illustrated by performing aging and calorimetric experiments on hyperquenched glasses. The features of the energy release peak, the endothermic pre-peak, and the real glass transition are discussed with respect to their physical origins.

Lund M.D., Yue Y.

The impact of aging in high humidity and water on the surface morphology and crystallization behavior of basaltic glass fibers has been studied using scanning electron microscopy, transmission electron microscopy, calorimetry and X-ray diffraction. The results show that interaction between the fibers and the surrounding media (high humidity or water at 70 °C) leads to chemical changes strongly affecting the surface morphology. The crystallization peak temperature of the basaltic glass fibers are increased without changing the onset temperature, this may be caused by a chemical depletion of network modifying elements.

Zhang L., Yang L., Lai C., Fu D., Lin J., Hou H., Zhao Y., Zhang Z., Bu C., Zheng X.

AbstractTensile strength is the major mechanical property of basalt continuous fiber and is closely related to their chemical composition. This study constructed a machine learning model framework to predict the tensile strength of basalt continuous fiber. The database included the characteristic variables of oxides and their derived parameters, as well as the target variables of tensile strength. The mean squared error (MSE) were calculated to evaluate the performance of six machine learning models of decision tree, kernel ridge regression, multivariable linear regression, support vector regression, random forest, and k‐nearest neighbors. The k‐nearest neighbors model had a minimum MSE and was tuned using the grid search method with cross‐validation. The optimal hyper‐parameters of the k‐nearest neighbors model were K = 6, p = 10, and the determination coefficient of the model reached the maximum of 0.7110 on the test data. The limitations and implications of the present study were also demonstrated. We finally expected that the constructed framework could achieve higher prediction accuracy for tensile strength at a low cost in the future.Highlights A machine learning framework was built to predict the tensile strength of BCF. Oxides and their derived parameters were used for modeling. K‐nearest neighbors performed best in predicting the tensile strength. The framework was robust, cost‐saving, and efficient.

Popov S.S., Gutnikov S.I.

In this work, the aim was to define the dependence of the strength of basalt fibers (BCF) on their chemical composition, characterized by two parameters: the NBO/T ratio and the acidity modulus Ma. It makes it possible to predict the change in the mechanical parameters of fibers from their composition, since basalt rocks have a significant drawback - the inconstancy of the chemical composition. Fibers of various chemical compositions were obtained based on 14 different basalt deposits. Pearson’s correlation coefficient for NBO/T and ultimate tensile strength was 0.79, and for acidity modulus and tensile strength it was 0.53. The tensile strength of tested fibers from different deposits ranges from 1495 to 3380 MPa. In addition, with the help of the Raman spectra analysis, it was confirmed that tensile strength can be largely determined by the influence of the chemical composition of basalts on their structure.

Liu H., Yu Y., Liu Y., Zhang M., Li L., Ma L., Sun Y., Wang W.

Basalt fiber (BF) has a high mechanical strength, excellent temperature resistance, good chemical stability, low energy consumption, and an environmentally friendly production process. In addition, BF-reinforced polymers (BFRPs) have good corrosion resistance and designability; thus, they meet the application requirements of electrical equipment, such as new conductors, insulating pull rods, and composite cross-arms. However, there are still a series of technical issues in the mass production of BF, and the stability of the products needs to be further improved. Therefore, the research on the production, modification, and application of BF is necessary. This paper discusses the chemical composition and production technology of BF, describes the morphology and properties of BF, summarizes the interface problems and modification methods of composites, and finally, introduces the application prospects of BF in the field of electrical materials, which is expected to provide a reference for the application and promotion of BFRP in the future.

Li M., Xing D., Zheng Q., Li H., Hao B., Ma P.

• Degradation mechanisms of basalt fiber (BF) in diverse alkalis were studied. • Morphology of BF evolved along with the deepen of alkali condition. • Ion exchange between K + in KOH with Na + in BF could enhance its tensile strength. • As-formed outer shell was made of metal hydroxides and silicates in KOH/NaOH. • Cluster-like crystals and amorphous deposits were proved to be CaCO 3 in Ca(OH) 2 . This paper presented the effect of concentration, temperature, and immersing time of alkali solutions (NaOH, KOH, Ca(OH) 2 ) on the morphology and mechanical property of basalt fiber (BF). Various techniques, including scanning electron microscopy, tensile test of single filament, infrared and Raman spectroscopy, were employed to characterize the fiber sample before and after treatment. The results showed that the surface of BF underwent changes from smooth surface to the rough one with deposited particles, and then the presence of shell with plate-like structures as the alkali condition became harsh. The tensile strength of BF followed a downward trend with the aggravation of the degradation. Unexpectedly, the strength of BF increased by more than 30% after KOH treatment due to the ion exchange between the Na + in fiber and K + in alkaline solution. In general, the degradation of BF in the alkali solution involved the breaking of Si-O-Si bond under OH − attack, and this mechanism was partly confirmed by the variation on the chemical composition of BF as characterized by Raman technique. In NaOH and KOH solutions, the in-situ formed outer shell and spherical particles on the BF surface were insoluble metal hydroxides (Fe and Mg) and silicates (Ca), and CaCO 3 cluster was noticed on the fiber surface when BF was treated in Ca(OH) 2 solution.

Yang C., Liu Z., Tong X., Guo L., Miao S., Jiang L., Li Y., Li H., Liu C.

In this study, basalt from a base in Hebei, China, was selected as the raw material. Water-quenched basalt glasses and basalt fibers were prepared at different homogenization times and temperatures. The water-quenched glass structure was characterized by XRD and a Raman spectrometer followed by fitting of their Raman spectra by Gaussian curves to obtain information about melt structure. The fiber performance was characterized by fiber strength meter and fiber fineness meter. The results demonstrate that homogenization time and temperature had significant effects on the structure of basalt melt. The degree of polymerization of the melt increased with increasing homogenization time and decreased with increasing homogenization temperature. The fiber strength increased with increasing the degree of polymerization. As the homogenization time and temperature increased, coefficients of variation of fiber strength and fiber diameter decreased, indicating enhanced fiber stability.

Cassetta M., Zanatta M., Biesuz M., Giarola M., Mariotto G.

Basalts are among the most abundant igneous rocks on Earth. Originated from the rapid cooling of magma erupted by volcanoes, they are increasingly used as raw materials in glass and ceramic technology due to their unique physico-chemical properties. The characteristics of basalts, like the glass transition temperature, are strongly controlled by their structure, which is a function of composition. Therefore, the investigation of the interplay between the intimate structure and the mechanical and physical properties of basalt glasses is of paramount importance in view of their industrial exploitation. Here, we present a Raman study of a set of synthetic-basalt glasses in which the occurrence of small chemical variations appreciably affects their glass transition temperature. We analyzed the Raman spectra focusing on both the spectral regions of the so-called nonbridging oxygens and of the boson peak. We show the existence of a scaling law for the boson peak of four synthetic-basalt glasses, and we infer from its breakdown the occurrence of a deep reorganization of the glass structure resulting from the Na–K replacement in the network, despite small variations of the other major elements.

Si J., Wang Z., Li J., Zuo C., Zhang P., Wei C., Wang J., Li W., Miao S.

• Continuous basalt fibers (CBFs) were produced from basalt mixtures. • The dosage of CaO inhibits the crystallization of spinel. • CaO promotes the crystallization of pyroxene and plagioclase. • The spinnability (capability of being spun) was improved. • The tensile strength of CBF was enhanced grealy. The influence of CaO on spinnability (the capability of being spun) of continuous basalt fibers (CBF) and strength property were investigated. The addition of CaO in raw basalts was found to eliminate spinel crystals (magnesioferrite), and to reduce frequency of fiber breaks during the fiber-drawing. The tensile strength of CBF was enhanced by 13% after addition 3% wt. of CaO to the starting materials. Excessive addition of CaO (>5.0%) would result in less spinnability and inferior mechanical strength. The structure of basaltic glass fibers with varying CaO contents was studied by various characterizations. Doping of CaO reduced the degree of fiber polymerization and increased the amount of non-bridging oxygen. Results showed that increase of CaO changes the crystallization behavior of fibers, inhibits the crystallization of spinel, and promotes the crystallization of pyroxene and plagioclase.

Tarrago M., Royo I., Martínez S., Garcia‐Valles M., Neuville D.R.

Gutnikov S.I., Popov S.S., Efremov V.A., Ma P., Lazoryak B.I.

This paper presents a study of the influence of basalt rocks’ phase composition, acidity modulus, and structural parameter NBO/T on the tensile strength and elastic modulus of basalt continuous fibers (BCFs) derived from them. A series of BCF samples based on 14 different basalt deposits was obtained under equal conditions. The tensile strength and elastic modulus of the BCFs from different deposits vary in the ranges of 1495–3380 MPa and 58.2–78.7 GPa, respectively. Using the original method of quantitative phase analysis based on the Rietveld method, the phase compositions of the 14 deposits were defined. All deposits can be used to obtain BCFs. In the studied natural rocks, the main component is tectosilicates; the mass content of framework aluminosilicates is in the range of 16.5–3.3 mass percent. The second main component is inosilicates; the mass content of chain aluminosilicates is in the range of 6.0–58.0 mass percent. The correlations among phase composition, acidity modulus, ratio of non-bridging oxygens to tetrahedral cations, tensile strength, and elastic modulus of the BCFs from the 14 different basalt deposits were calculated. There were strong positive correlation between tectosilicate minerals mass content and elastic modulus [Pearson correlation coefficient (PCC) of 0.7] and strong negative correlation between content of chain and layered aluminosilicates and elastic modulus (PCC of − 0.74).

I. Gutnikov S., S. Zhukovskaya E., S. Popov S., I. Lazoryak B.

This work presents the study of the dependence of the basalt continuous fibers (BCF) tensile strength on their chemical composition. 14 different basalt deposits were used to obtain continuous fibers by a laboratory scale system. Based on the data for more than 15 articles focused on natural basalt continuous fibers (32 different compositions) and experimental data of 14 experimental BCF series, the correlation of the tensile strength, the acid modulus and the NBO/T parameter was calculated. The PCC (pearson correlation coefficient) value of NBO/T and the tensile strength was 0.79, for acidity modulus and tensile strength -0.53.Raman data for experimental BCF confirm the significant influence of the chemical composition of basalts on their structure, which determines their tensile strength. With a decrease in NBO/T, the observed ratio between the Raman bands at low-and high-frequencies gradually increases.

Gutnikov S.I., Pavlov Y.V., Zhukovskaya E.S.

The influence of low-frequency vibrational treatment on the crystallization of basalt wool fibers was studied. In this work, three series of samples were investigated. The first sample set was only one-sided heated at temperatures from 300 °C to 900 °C for 24 h. The second sample set was after only vibrational treatment with a frequency of 50 Hz and oscillations amplitude of 1 mm for 6–48 h. The third sample set was after simultaneous treatment of one-sided heating and vibration at temperatures from 300 °C to 600 °C with a frequency of 50 Hz and oscillations amplitude of 1 mm for 24 h. It is shown that at temperatures close to the glass transition temperature, vibration can influence on the relaxation processes in glasses and accelerate them. Mechanism of glass structure transformation in the basalt fiber does not change, but it starts at a slightly lower temperature. That is a consequence of an additional low-energy vibrational treatment. The vibrational treatment intensifies the crystallization process in basalt fibers and decreases the service temperature of the material by at least 40–50 °C.

Shan Z., Liu J., Shi F., Liu S., Yu L., Wu C., Wang C., Liu T.

The lithium disilicate (LD) glass-ceramics with the SiO2-Li2O-R2O-Al2O3-P2O5-CeO2 system were prepared by adding R2O (R = K, Rb, Cs) as modifier. The effects of R2O addition on the crystallization behavior, microstructure and fracture strength of the LD glass-ceramics were investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) etc. The results indicate that the fracture strength of LD glass-ceramics could be improved greatly by introducing Rb2O or Cs2O instead of K2O, therein, introducing Rb2O instead of K2O improved the fracture strength by 26% and Cs2O substituting K2O improved the fracture strength by 37%. The crystallization activation energy of different crystal phase was calculated. It was found that the lower the crystallization activation energy of lithium disilicate is, the higher the fracture strength of LD glass-ceramic achieves. Based on the results, a new chemical strengthening theory of LD glass-ceramic has been proposed, which is of great significance for developing LD dental restorative materials and other functional glasses.

Kuzmin K.L., Gutnikov S.I., Zhukovskaya E.S., Lazoryak B.I.

In the present research the dependence of compositional variations on the basaltic glass fibers mechanical properties was explored. Addition of 15 mol % MgO or 5 mol % ZnO led to enhanced for tensile strength up to 43% and 47% and for modulus up to 13% and 25% respectively. The structure of basaltic glass fibers with varying MgO and ZnO contents was investigated by solid-state 29 Si and 27 Al nuclear magnetic resonance with magic angle spinning (MAS-NMR) and infrared (IR) spectroscopy. It was indicated that the increase of MgO and ZnO contents slightly decreased the degree of network polymerization. 27 Al MAS NMR exhibit a peak consistent with tetrahedral aluminum units AlO 4 . The noticeable fraction peaks of narrow octahedral aluminum units AlO 6 are observed. Presence of aluminum cations in coordination 4 and 6 was confirmed by IR spectroscopy. In order to study their crystallization ability the glasses were heated at various temperatures for various time periods with following self-cooling. The crystalline phases were identified by X-ray diffraction analysis. Obtained results have shown the possibility to increase mechanical properties of continuous fibers and composites on their base by 50–60%.