Influence of vibration on basalt fiber crystallization at high temperature

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Influence of vibration on basalt fiber crystallization at high temperature ⁎

Sergey I. Gutnikov , Yuriy V. Pavlov, Evgeniya S. Zhukovskaya Chemistry Department, Lomonosov Moscow State University, Moscow 119991, Russia

A R T I C LE I N FO

A B S T R A C T

Keywords: Basalt fibers Basalt wool Vibration Crystallization

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.

1. Introduction There are two types of basalt fiber that are widely used in recent years: continuous fiber and wool. The chemical composition [1,2], thermal history [3], production method [4,5], diameter [6], the cooling rate [7] and other parameters determine the properties of basalt fiber substantially. Basalt wool is widely used as thermal insulation material. Its most common area of application is building. The entire temperature range of application in building is narrow, from minus 50 to plus 70 °C [8,9]. At the same time, basalt and rock wool materials are often used in power plants and chemical plants. In these cases, the service temperature can reach 600 °C. Moreover, the high temperature in the production plants can be accompanied by a constant equipment vibration. Basalt and basaltic glass fibers undergo crystallization as the temperature rises. The initial processes of the crystallization for basaltic fibers under thermal treatment have been studied quite well [10–13]. Crystallization in basaltic glasses begins with liquid immiscibility. Then iron-rich phase promotes formation of a first crystal phase with spinel structure (spinelide) [14,15]. With a following thermal treatment, the spinel crystals act as nuclei for crystallization of monoclinic pyroxene crystals. During crystallization, the fibers lose their mechanical strength and break. Materials on their base, like insulation, lose their form and destruct [16]. Basalt and basalt like wool materials have good sound absorption coefficients, especially at medium and high frequencies. It is shown that they can effectively absorb acoustic energy [17,18]. The fundamental ⁎

bulk characteristic for a sound absorbing material is its porosity. Useful parameters to compare the sound-absorbing characteristics of the fibers are their diameter, length, and the regularity of shape. In general, the normal incidence absorption coefficient increases when increasing both density and thickness [19]. A vibration treatment is an action with weak energy compared to the temperature influence. Nevertheless, it is known that vibration can not only significantly influence, but also control the processes of crystallization in melts [20,21]. In this paper, the influence of simultaneous thermal and vibrational treatment on the crystallization process in silicate glasses is considered for the first time. This question for basaltic fibers was not previously studied at all also. It should be noted that there is no standard procedure for measuring vibration resistance for insulation materials. According to ASTM C 1139 there shall be a maximum of 0.50% weight loss and the insulation shall not settle and lose thickness after vibration test. The total period of the test shall be 100 h at a frequency of 12 Hz with an amplitude of vibration of 3.3 mm only. The precision of this test method is not known because interlaboratory data are not available. This test method may not be suitable for use in specifications or in case of disputed results as long as these data are not available. In practice, some production companies use the same procedure but under other conditions: frequency of 50 Hz, an amplitude of vibration of 1 mm, period of the test of 3 h. This paper is pioneering in this field of work. We decided to start with conditions similar to those that we used in our previous studies.

Corresponding author. E-mail address: [email protected] (S.I. Gutnikov).

https://doi.org/10.1016/j.jnoncrysol.2018.03.008 Received 30 September 2017; Received in revised form 17 February 2018; Accepted 6 March 2018 0022-3093/ © 2018 Published by Elsevier B.V.

Please cite this article as: Gutnikov, S.I., Journal of Non-Crystalline Solids (2018), https://doi.org/10.1016/j.jnoncrysol.2018.03.008

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Fig. 1. SEM image of basalt wool fibers.

2.4. Thermal analysis

Moreover, the main goal of this work is primarily to assess the effect of vibration on the crystallization process, and not on the measuring of vibration resistance of the material. In future works, we are going to determine the influence of both amplitudes and frequencies on the processes of destruction of insulation materials. This work is interesting both from the applied point of view (study of material destruction based on mass loss and thermal conductivity) and from the fundamental one (the influence of vibration on the crystallization process in glasses).

Differential scanning calorimetry (DSC) was performed on Netzsch STA Jupiter 449C equipped with a high-temperature furnace in a temperature range 300–700 °C with heating rate 10°/min on high-sensitivity sample holder with Pt/Pt-Rh thermocouples. For measurement fibers were ground with an agate mortar and pestle. 2.5. Scanning electron microscope analysis A JEOL JSM-6390LA microscope was used for the scanning electron microscope (SEM) analysis. The accelerating voltage was set to 20 kV. The morphology of the fibers was determined in secondary electron imaging (SEI) mode. Energy-dispersive X-ray (EDX) analysis was carried out on a JEOL EX-54175 JMH system. Before the examinations all the fibers were coated with a conducting carbon layer.

2. Material and methods 2.1. Samples Basalt wool fiber (BWF) under investigation was obtained at the pilot industrial line. The chemical composition determined by X-ray fluorescence analysis is follows: 54.0 ± 0.5 SiO2, 11.6 ± 0.3 Al2O3, 4.3 ± 0.3 Na2O, 0.79 ± 0.2 K2O, 9.4 ± 0.3 CaO, 12.2 ± 0.3 FeO + Fe2O3, 1.7 ± 0.2 TiO2, 5.8 ± 0.2 MgO (mol%). The average basalt fiber diameters were found by SEM image analyses of approximately 500–600 single fibers were in range from 0.5 to 6 μm (Fig. 1). Basalt wool fibers were without sizing.

2.6. Thermal conductivity The thermal conductivity was measured with a heat flux-meter operating in a temperature range 20–70 °C. This non-commercial instrument was calibrated using NIST traceable standards. The ceramic spacers were used in measurements, thus the samples thickness was fixed at 5 mm. The other measurement parameters were chosen according to ISO 8301.

2.2. X-ray fluorescence analysis 3. Experimental X-ray fluorescence analysis of the specimens was performed on a PANanalytical Axios Advanced spectrometer. Characteristic X-rays were excited using a 4 kW Rh-anode X-ray tube. The excited radiation was recorded by a scanning channel with five exchangeable wave crystals and a detector. Measurements were performed in transmission geometry in vacuum. For measurements, it was used pellets of investigated glass with a binder.

To perform this work, it was created a laboratory scale plant that allows simultaneous one-sided thermal heating and vibrational treatment at a frequency of 50 Hz and an oscillations amplitude of 1 mm. A sample size was 300 × 300 mm. In each series two samples were investigated. The scheme of laboratory scaled plant is shown in Fig. 2. Using this laboratory scale plant, three series of experiments were performed:

• One-sided heating at temperatures of 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C for 24 h (HT series). • Vibrational treatment with a frequency of 50 Hz and oscillations amplitude of 1 mm for 6, 12, 18, 24, 36 and 48 h (V series). • Simultaneous treatment of one-sided heating and vibration at tem-

2.3. XRD studies X-ray diffraction (XRD) was made at room temperature on Thermo ARL X'TRA powder diffractometer (CuKα1 radiation, λ = 1.54060 Å; CuKα2 radiation, λ = 1.54443 Å). XRD patterns were collected in an angular range 2θ = 10°–60° at a scan step 2θ = 0.02° and a scan rate of 1° (2θ)/min. The phases were identified using the International Center for Diffraction Data (ICDD) database.

peratures of 300 °C, 400 °C, 500 °C, 600 °C with a frequency of 50 Hz and an oscillations amplitude of 1 mm for 24 h (HT + V series).

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Fig. 2. Scheme of laboratory scale plant for simultaneous one-sided thermal heating and vibrational treatment.

phase composition of the samples does not change. We believe the spinelide particles act as nucleation sites for the crystallization of pyroxene phase [ICDD no. 24-201] and hematite [ICDD no. 89-598]. The results of the investigation of HT series are shown in Fig. 4a. The phase composition of the samples of V + HT series agrees with the results for HT series. However, it can be noted that the first crystalline phase was identified for V + HT series already at 500 °C (Fig. 4b).

After appropriate processing, mass loss and thermal conductivity were measured for each series of samples at an average temperature of 30 °C. 4. Results 4.1. Mass loss and thermal conductivity

4.3. Thermal analysis

Mass loss and thermal conductivity were chosen as parameters that characterize the degree of material destruction. The results of changes in mass loss and in thermal conductivity for HT series, V series and HT + V series are shown in Fig. 3. It was found that in the case of HT series, significant changes in both mass loss and thermal conductivity occur at temperatures above 500 °C (Fig. 3а). In the case of only vibrational treatment, samples do not undergo significant changes. Mass loss and thermal conductivity do not change with increasing the treatment time from 6 to 48 h. Measured values of mass loss and thermal conductivity remain within the measurement error (0.015% and 35 mW/mK respectively) (Fig. 3b). The most significant changes in properties were observed with simultaneous thermal and vibration treatment. The significant increase in mass loss was observed at temperatures above 400 °C. It is also observed that thermal conductivity increases immediately from 39 mW/mK up to 63 mW/mK with a change in the temperature of the treatment from 300 to 600 °C (Fig. 3c).

To establish the difference in crystallization initial stage in HT and HT + V series, samples annealed at 400 and 500 °C and simultaneously annealed and vibrated at 400 and 500 °C were examined by the DSC method in the temperature range from 300 to 700 °C. This method was also used to investigate the samples without treatment. Fig. 5 shows the DSC curves of the samples. It can be noted that there are exothermic peaks on the DSC curves in temperature range from 400 °C to 550 °C in both HT and HT + V series. In the case of the HT + V series, the peaks are narrower and located by 20–30° lower in temperature than that for HT series. 5. Discussion The influence of the vibrational treatment on the properties of silicate and oxide melts and glasses is insufficiently investigated. On the one hand, the vibrational treatment is a low-energy action compared to the thermal treatment. On the other hand, in some cases, it has a very significant influence on the processes occurring in the melts. Several works are also devoted to crystallization in organic systems at vibration [22]. One of the most popular methods to control the solidification structure under the action of different external factors is crystallization of melts under vibration treatment [20]. For example, the cast structure

4.2. XRD studies All obtained series of samples were investigated by the XRD analysis. Samples without temperature treatment (V series) are amorphous. For samples of HT series, crystalline phases are identified at a temperature above 600 °C. In the temperature range from 600 to 900 °C, the 3

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Fig. 3. a) Mass loss and thermal conductivity of basalt wool fibers after one-sided heating at temperatures of 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C for 24 h (HT series); b) mass loss and thermal conductivity of basalt wool fibers after vibrational treatment with a frequency of 50 Hz and amplitude of oscillations of 1 mm for 6, 12, 18, 24, 36 and 48 h (V series); c) mass loss and thermal conductivity of basalt wool fibers after simultaneous treatment of one-sided heating at temperatures of 300 °C, 400 °C, 500 °C, 600 °C and vibration with a frequency of 50 Hz and an amplitude of oscillations of 1 mm for 24 h (HT + V series).

glasses and fibers. At temperatures close to the glass transition temperature, vibration can influence the relaxation processes in glasses. Even if these processes are insignificant, vibration is most likely to accelerate them. The results obtained in our work confirm this assumption. Fig. 6 clearly demonstrate the “synergistic effect” of a thermal and vibrational treatment. It can be noted that the vibrational treatment does not have an effect on the material at room temperature. It becomes considerable at temperatures above 450 °C. The presented diagrams show a significant increase in mass loss from 2–4% at 300 °C to 10% at 600 °C (Fig. 6a). It can be expected that this effect will have a dependence on the density of the material [9]. In this work was found that the magnesium silicate fibers are much dustier than any of the calcium magnesium silicate or

fragmentation under ultrasonic or low-frequency vibration is one of the widely used method in metallurgy [21]. Despite the fact that most of the experimental studies investigate the process of crystallization in metal and organic substances, the theoretical work describes the regularities that occur during vibration in fluids [20–22]. In our opinion, some of these conclusions can be applied to silicate glasses. The vibrational treatment on the melt leads to an intensive nucleation of new crystals. Two main mechanisms of dynamic crystals nucleation under the vibrational treatment are distinguished. In the first case, the process of spontaneous nucleation of crystals due to supercooling takes place in the liquid. In the other case, under the vibration treatment, the number of crystals in the solidifying liquid sharply increases due to the fragmentation of already existing crystals. We believe that such mechanisms can occur in basaltic and silicate 4

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Fig. 4. a) XRD patterns of basalt wool fibers after one-sided heating at temperatures of 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C for 24 h (HT series); b) XRD patterns of basalt wool fibers after one-sided heating at temperatures of 300 °C, 400 °C, 500 °C for 24 h (HT series) and basalt wool fibers after simultaneous treatment of one-sided heating at temperatures of 300 °C, 400 °C, 500 °C and vibration with a frequency of 50 Hz and an amplitude of oscillations of 1 mm for 24 h (HT + V series). (v – pyroxene phase, ○ - hematite, x - spinel phase).

it does not play a role, since all measurements were carried out at near room temperature. Thus, the change in thermal conductivity is entirely the result of crystallization in the material and its destruction in the process of vibration. The relationship between the thermal treatment and relaxation process in basaltic glass fibers is described in the literature. It was found that the enthalpy relaxation is initiated around 250 °C although it takes place with the highest rate around 450 °C [7]. The initial enthalpy relaxation does influence neither the fracture mechanism nor the tensile strength of stone wool fibers. Heat treatment at temperatures above 450 °C, however, results in faster relaxations and a reduction in the resistance to fracture. The enthalpy relaxation of basaltic glass indicates that the low temperature relaxation might be correlated to β-relaxation and that the main relaxation at slightly higher temperatures might be correlated to α-relaxation [26]. The destruction in fibers indicates that the initial enthalpy relaxation (local β-relaxations) does not influence the tensile strength of stone wool fibers, whereas the main enthalpy relaxation that might be connected to the α-relaxation in the glass structure directly affects the strength of stone wool fibers [27]. Oxidation of stone wool fibers begins at 450 °C [27,28]. Above this temperature, the stone wool surface starts to crystallize that leads to large changes both in structure and in the fiber surfaces properties. The obtained results correlate with the data described in the literature. In our case the mass loss of the samples upon mechanical treatment can also be considered as a consequence of the fragility of the fibers. On the DSC curves shown in Fig. 5, it can be noted the significant narrowing of the exothermic peaks in the 400–500 °C temperature range. It is also important to note a small peak shift in the region of lower temperatures with increasing treatment temperature. Thus, in principle, the mechanism of glass structure conversion 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. In addition, it is very likely that crystals of the spinel phase that formed in the system at a certain temperature can split up somewhat due to the vibrational load. As a consequence, there is a sharp increase in the intensity of the crystallization process due to an increase in the number of crystallization centers. The results obtained in this work indicate that vibration intensifies crystallization processes by an additional 15–20%.

Fig. 5. DSC curves of basalt wool fibers without treatment (short dot line), basalt wool fibers after one-sided heating at temperatures of 400 °C and 500 °C for 24 h (HT series, short dash lines) and basalt wool fibers after simultaneous treatment of one-sided heating at temperatures of 400 °C and 500 °C and vibration with a frequency of 50 Hz and an amplitude of oscillations of 1 mm for 24 h (HT + V series, solid lines).

ceramic fiber blankets, even with the same density and thickness samples. Material with the most recently used composition of calcium magnesium silicate was less dusty than the other blankets tested. It is important to note that annealing at temperatures above 450 °C also leads to a decrease in the mechanical properties of basaltic fibers [23,24]. For fibers obtained as wool this effect is not as significant as for continuous fibers. The oriented local structure is energetically so unstable that it relaxes at very low temperatures, e.g., already at 0.5 Tg [7]. The thermal conductivity of the material also decreases significantly (Fig. 6b). With increasing treatment temperature from 300 °C to 600 °C with simultaneous vibration treatment, the thermal conductivity increases from 39 to 63 mW/mK, i.e. by 60%. At the same time, when there is no vibration, the increase is only 13% from 34.5 to 39 mW/mK. The fact that the heat conductivity increases for a basalt wool materials with increasing temperature is well known [8,19]. Thus, not only temperature dependence of the thermal conductivity of the solid plays a role in this process. At high temperatures, above about 300 °C, radiation component of heat transfer process makes a significant contribution [25]. In the experiment presented in this paper,

6. Conclusions The influence of low-energy vibrational treatment on the crystallization of basalt fibers has been studied. A laboratory scale plant was created for the simultaneous one-sided thermal and vibrational 5

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Acknowledgments The work was supported by Russian Foundation for Basic Research and Moscow city Government according to the research project No 1538-70018 «mol_а_mos». References [1] R. Conradt, Chemical structure, medium range order, and crystalline reference state of multicomponent oxide liquids and glasses, J. Non-Cryst. Solids 345–346 (2004) 16–23, http://dx.doi.org/10.1016/j.jnoncrysol.2004.07.038. [2] S.I. Gutnikov, A.P. Malakho, B.I. Lazoryak, V.S. Loginov, Influence of alumina on the properties of continuous basalt fibers, Russ. J. Inorg. Chem. 54 (2009) 191–196, http://dx.doi.org/10.1134/S0036023609020041. [3] M.M. Smedskjaer, M. Jensen, Y. Yue, Effect of thermal history and chemical composition on hardness of silicate glasses, J. Non-Cryst. Solids 356 (2010) 893–897, http://dx.doi.org/10.1016/j.jnoncrysol.2009.12.030. [4] Y. Zhang, Y. Vulfson, Q. Zheng, J. Luo, S.H. Kim, Y. Yue, Impact of fiberizing method on physical properties of glass wool fibers, J. Non-Cryst. Solids (2017) 0–1, http://dx.doi.org/10.1016/j.jnoncrysol.2017.09.039. [5] K.L. Kuzmin, E.S. Zhukovskaya, S.I. Gutnikov, Y.V. Pavlov, B.I. Lazoryak, Effects of Ion Exchange on the Mechanical Properties of Basaltic Glass Fibers, Int. J. Appl. Glas. Sci. 7 (2016). [6] W.H. Otto, Relationship of tensile strength of glass fibers to diameter, J. Am. Ceram. Soc. 38 (2006) 122–125, http://dx.doi.org/10.1111/j.1151-2916.1955.tb14588.x. [7] J. Deubener, Y. Yue, H. Bornhöft, M. Ya, Decoupling between birefringence decay, enthalpy relaxation and viscous flow in calcium boroalumosilicate glasses, Chem. Geol. 256 (2008) 298–304, http://dx.doi.org/10.1016/j.chemgeo.2008.06.052. [8] A. Karamanos, S. Hadiarakou, A.M. Papadopoulos, The impact of temperature and moisture on the thermal performance of stone wool, Energy Build. 40 (2008) 1402–1411, http://dx.doi.org/10.1016/j.enbuild.2008.01.004. [9] P. Class, P. Deghilage, R.C. Brown, Dustiness of different high-temperature insulation wools and refractory ceramic fibres, Ann. Occup. Hyg. 45 (2001) 381–384 http://www.ncbi.nlm.nih.gov/pubmed/11418088. [10] A. Karamanov, M. Pelino, Crystallization phenomena in iron-rich glasses, J. NonCryst. Solids 281 (2001) 139–151, http://dx.doi.org/10.1016/S0022-3093(00) 00436-1. [11] M.S. Manylov, S.I. Gutnikov, K.V. Pokholok, B.I. Lazoryak, Y.V. Lipatov, Crystallization mechanism of basalt glass fibers in air, Mendeleev Commun. 23 (2013) 361–363, http://dx.doi.org/10.1016/j.mencom.2013.11.021. [12] P.M. Sørensen, M. Pind, Y.Z. Yue, R.D. Rawlings, A.R. Boccaccini, E.R. Nielsen, Effect of the redox state and concentration of iron on the crystallization behavior of iron-rich aluminosilicate glasses, J. Non-Cryst. Solids 351 (2005) 1246–1253, http://dx.doi.org/10.1016/j.jnoncrysol.2005.03.015. [13] N. Wang, S. Hou, H.Y. Jin, Crystallization behavior of heat-treated basalt fiber, Adv. Mater. Res. 560–561 (2012) 3–7, http://dx.doi.org/10.4028/www.scientific.net/ AMR.560-561.3. [14] A. Karamanov, P. Pisciella, M. Pelino, The crystallisation kinetics of iron rich glass in different atmospheres, J. Eur. Ceram. Soc. 20 (2000) 2233–2237, http://dx.doi. org/10.1016/S0955-2219(00)00077-7. [15] A. Karamanov, S. Ergul, M. Akyildiz, M. Pelino, Sinter-crystallization of a glass obtained from basaltic tuffs, J. Non-Cryst. Solids 354 (2008) 290–295, http://dx. doi.org/10.1016/j.jnoncrysol.2007.07.040. [16] J. Militký, V. Kovačič, J. Rubnerová, Influence of thermal treatment on tensile failure of basalt fibers, Eng. Fract. Mech. 69 (2002) 1025–1033, http://dx.doi.org/ 10.1016/S0013-7944(01)00119-9. [17] U. Berardi, G. Iannace, Predicting the sound absorption of natural materials: best-fit inverse laws for the acoustic impedance and the propagation constant, Appl. Acoust. 115 (2017) 131–138, http://dx.doi.org/10.1016/j.apacoust.2016.08.012. [18] U. Berardi, G. Iannace, M. Di Gabriele, G. Iannace, M. Di Gabriele, 22nd International Congress on Acoustics. Acoustics for the 21st Century Characterization of Sheep Wool Panels for Room Acoustic Applications, 15001 (2017), http://dx.doi.org/10.1121/2.0000336. [19] U. Berardi, M. Naldi, The impact of the temperature dependent thermal conductivity of insulating materials on the effective building envelope performance, Energy Build. 144 (2017) 262–275, http://dx.doi.org/10.1016/j.enbuild.2017.03. 052. [20] D.V. Lyubimov, T.P. Lyubimova, S. Meradji, B. Roux, Vibrational control of crystal growth from liquid phase, J. Cryst. Growth 180 (1997) 648–659, http://dx.doi.org/ 10.1016/S0022-0248(97)00294-7. [21] I.C. Avetissov, E.A. Sukhanova, A.V. Khomyakov, A.Y. Zinovjev, V.A. Kostikov, E.V. Zharikov, Simulation and crystal growth of CdTe by axial vibration control technique in Bridgman configuration, J. Cryst. Growth 318 (2011) 528–532, http:// dx.doi.org/10.1016/j.jcrysgro.2010.10.055. [22] O.P. Fedorov, E.L. Zhivolub, Effect of low-frequency vibration on nucleation of crystals in supercooled melts, Crystallogr. Rep. 47 (2002) 519–523, http://dx.doi. org/10.1134/1.1481945. [23] M.D. Lund, Y. Yue, Impact of drawing stress on the tensile strength of oxide glass fibers, J. Am. Ceram. Soc. 93 (2010) 3236–3243, http://dx.doi.org/10.1111/j. 1551-2916.2010.03879.x. [24] F. Sarasini, J. Tirillò, M.C. Seghini, Influence of thermal conditioning on tensile behaviour of single basalt fibres, Compos. Part B 132 (2018) 77–86, http://dx.doi. org/10.1016/j.compositesb.2017.08.014.

Fig. 6. a) Mass loss of basalt wool fibers after simultaneous treatment of one-sided heating at various temperatures and vibration. b) Thermal conductivity of basalt wool fibers after simultaneous treatment of one-sided heating at various temperatures and vibration. One-sided heating of the samples at temperatures of 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C for 24 h (HT series). Vibrational treatment with a frequency of 50 Hz and oscillations amplitude of 1 mm for 6, 12, 18, 24, 36 and 48 h (V series). Simultaneous treatment of one-sided heating and vibration at temperatures of 300 °C, 400 °C, 500 °C, 600 °C with a frequency of 50 Hz and an oscillations amplitude of 1 mm for 24 h (HT + V series).

treatment. Three series of samples were obtained: after only one-sided heating at temperatures of 300 °C, 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C for 24 h, after only vibrational treatment on a sample with a frequency of 50 Hz and amplitude of oscillations of 1 mm for 6, 12, 18, 24, 36 and 48 h, after simultaneous treatment of one-sided heating and vibration at temperatures of 300 °C, 400 °C, 500 °C, 600 °C with a frequency of 50 Hz and an amplitude of oscillations of 1 mm for 24 h. The obtained samples were studied by thermal analysis and XRD. Mass loss and thermal conductivity of all obtained samples was measured. It is shown that the vibrational treatment intensifies the crystallization process in basalt fibers and decreases the service temperature of the material by at least 40–50 °C. At the same time, the crystallization mechanism does not fundamentally change.

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[27] Y. Yue, M. Korsgaard, L.F. Kirkegaard, G. Heide, Formation of a nanocrystalline layer on the surface of stone wool fibers, J. Am. Ceram. Soc. 92 (2009) 62–67, http://dx.doi.org/10.1111/j.1551-2916.2008.02801.x. [28] Y.V. Lipatov, I.V. Arkhangelsky, A.V. Dunaev, S.I. Gutnikov, M.S. Manylov, B.I. Lazoryak, Crystallization of zirconia doped basalt fibers, Thermochim. Acta 575 (2014) 238–243, http://dx.doi.org/10.1016/j.tca.2013.11.002.

[25] I.I. Vishnevskii, E.I. Akselrod, N.D. Talyanskaya, A.D. Melentev, D.B. Glushkova, The thermal conductivity of refractory fiber products, Refractories 16 (1975) 408–413, http://dx.doi.org/10.1007/BF01284706. [26] L. Hornbøll, Y. Yue, Enthalpy relaxation in hyperquenched glasses of different fragility, J. Non-Cryst. Solids 354 (2008) 1862–1870, http://dx.doi.org/10.1016/j. jnoncrysol.2007.10.023.

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