The effect of lithium fluoride on the thermal stability and thermoluminescence properties of borosilicate glass and glass-ceramics

The oxyfluoride glass and glass-ceramics from the LiF-B₂O₃-SiO₂ system are developed. The stable glass can be produced in the range of 20–40 mol% LiF. The effect of LiF admixture on the thermal stability of the glass as well as the thermoluminescence (TL) properties such as glow curves shape is studied. The results show that the increase of lithium fluoride content in the borosilicate glass causes efficiency enhancement of the thermoluminescence signal. We have clearly stated that the process of controlled crystallization of the oxyfluoride glasses can lead again to increased intensity of the TL process. The glass-ceramics with 40 mol% LiF reveals similar level of TL signal to commercially used doped LiF material and can be considered as active material for alpha and beta radiation detectors.     

Impact of the cation field strength on physical properties and structures of alkali and alkaline-earth borosilicate glasses

The impact of the cation field strength (CFS) of the glass network-modifier cations on the structure and properties of borosilicate glasses (BS) were examined for a large ensemble of mixed-cation (R/2)M₍₂₎O–(R/2)Na₂O–B₂O₃–KSiO₂ glasses with M⁺ ={Li⁺, Na⁺, K⁺, Rb⁺} and M²⁺ ={Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺} from four series of {K, R} combinations of K = n(SiO₂)/n(B₂O₃) = {2.0, 4.0} and R =[n(M₍₂₎O) ?+ ?n(Na₂O)]/n(B₂O₃) = {0.75, 2.1}. Combined with results from La³⁺ bearing glasses enabled the probing of physical-property variations across a wide CFS range, encompassing the glass transition temperature (T_g), density, molar volume and compactness, as well as the hardness (H) and Young's modulus (E). We discuss the inferred composition–structure/CFS–property relationships. Each of T_g, H, and E revealed a non-linear dependence against the CFS and a strong T_g/H correlation, where each property is maximized for the largest alkaline-earth metal cations, i.e., Sr²⁺ and Ba²⁺, along with the high-CFS La³⁺ species. The ¹¹B MAS NMR-derived fractional BO₄ populations decreased linearly with the average M^z+/Na⁺ CFS within both K–0.75 glass branches, whereas the NBO-rich K–2.1 glasses manifested more complex trends. Comparisons with results from RM₂O–B₂O₃–KSiO₂ glasses suggested no significant “mixed alkali effect”.     

Experimental investigation on thermal healing of subsurface damage in borosilicate glass

Subsurface damage (SSD) is the fracture and deformation near the surface of brittle optical materials, caused by surface lapping or grinding. The existence of SSD dramatically influences the performance of optical glass and reduces the laser-induced damage threshold. Subsurface cracks of borosilicate glass can be spontaneously healed when heated under appropriate conditions. In this paper, thermal healing experiments of borosilicate glass (BK7) subsurface cracks are conducted on typical cracks induced by an indentation process, and the effects of the Beilby layer, temperature, crack depth, and water vapor pressure are studied. A semi-empirical relation is obtained through the regression of experimental results to describe the variation of subsurface crack length. Finally, a healing experiment is performed on the subsurface damage formed by grinding. The detection results show both the damage density and maximum damage depth have been reduced after heat treatment, demonstrating the effectiveness of the thermal healing method on eliminating glass subsurface damage.     

Effect of Zr ions on the structure and optical properties of lithium borosilicate molybdate glass system

The glass system with the composition [(20-x) MoO₃– x ZrO₂–15 SiO₂– 65 Li₂B₄O₇, x = 0, 1, 2, 3, 4, and 5 mol %] was successfully synthesized using the melt quenching method. The XRD results of this glassy system confirmed the glassy nature of the prepared glasses. The density of this glassy system presented higher values while the molar volume provided lower values with increasing ZrO₂ content. The FTIR result showed that the spectrum of each sample consisted of broad bands that de-convoluted into several peaks. These peaks were characterized and the structure of each sample was recognized. Additionally, the optical measurements showed that sample x = 0 mol% provided a sharp ultra-violet cut-off at 380 nm, while the other samples showed a transition peak in the (210–230) nm range. The energy of optical band gaps of these glass samples decreased and the Urbach energy increased by increasing ZrO₂ content. Moreover, the different optical parameters of these glass samples were calculated and showed that the studied glasses could be considered promising materials to be used in different optical applications such as nonlinearity and optoelectronics.     

The effect of coal properties on the viscosity of coal-water slurries

Studies on coal-water slurries (CWSs) have been conducted for many years to replace fuel oil. In this research project, the effect of coal properties on CWSs have been investigated using two Turkish coals of different ranks and a Siberian bituminous coal. Physical, chemical and surface properties of coal samples were determined. Furthermore, adsorption tests were carried out in order to put forward the effect of additive adsorption on the viscosity of CWSs. Viscosity measurements were realized for CWSs of various solid ratios by weight that were prepared using coal samples having mean particle sizes of 19, 35 and 50 μm.     

Thermal study of melting,transition and crystallization of rubidium and cesium borosilicate glasses

Thermal properties of the synthesized rubidium and cesium borosilicate glasses have been studied by differential scanning calorimetry. The values of glass transition temperature (T_g) and crystallization temperature (T_c) have been determined, the characteristic features of crystallization process have been established at various heat treatment conditions. Glass crystallization products have been characterized by powder X-ray diffraction. Information on the properties of the glasses makes it possible to correct the heat treatment parameters for glass-containing nuclear waste matrix materials.     

Mechanical and thermal properties of h-BN based composite containing dual glass phases at elevated temperatures

High-temperature mechanical and thermal properties of h-BN based composite containing amorphous silica and Yb-riched silicate glass phases were systematically investigated in this work. Owing to anisotropic microstructure of h-BN matrix, the obtained composite demonstrates anisotropic mechanical and thermal properties. The composite possesses higher elastic modulus at 1673?K than that at room temperature and presents excellent high-temperature stiffness. Flexural strengths in parallel and perpendicular directions reach 496?±?22 and 258?±?21?MPa at?1073?K, respectively, and increases by 74 and 66% compared with the room-temperature strengths of 285?±?4?and 155?±?5?MPa. The composite containing dual glass phases shows lower coefficients of thermal expansion in the temperature range of 473–900?K, the values are ?1.4?×?10^?6 and 0.3?×?10^?6 ?K^?1 for the perpendicular and parallel directions, respectively. Thermal conductivities in the perpendicular and parallel directions at 373?K are 24.8 and 14.8?W?m^?1?K^?1, respectively, and then decrease to 14.9 and 9.3?W?m^?1?K^?1 at 1473?K.     

Structure,mechanical properties and thermal stability of Ti1-xSixN coatings

Ti_1-xSi_xN coating is a promising candidate for wear resistant applications due to their super-hardness and high thermal stability. Here, we explored the structure, mechanical properties and thermal stability of Ti_1-xSi_xN (x?=?0, 0.13, 0.17 and 0.22) coatings deposited by cathodic arc evaporation. Monolithically grown Si-containing Ti_1-xSi_xN coatings, which are Si-solution in TiN for x?=?0.13 and 0.17, reveal a high hardness of 39.4?±?0.67 and 40.6?±?0.72?GPa, respectively. Then Ti_1-xSi_xN transforms into a nanocomposite structure consisting of cubic Ti(Si)N nanocrystallite enveloped by the amorphous SiN_x tissue phase for x?=?0.22, which exhibits a high hardness of 40.0?±?0.6?GPa. However, increasing of Si content leads to a significant increase in compressive stress from ?0.63?GPa for x?=?0 to ?3.78?GPa for x?=?0.13 to ?4.54?GPa for x?=?0.17 to ?5.51?GPa for x?=?0.22. The hardness of Ti_1-xSi_xN coatings can be maintained up to ~ 1000?°C due to the suppressed grain growth, and then decreases for further elevated annealing temperature, whereas the TiN coating exhibits a continuous drop in hardness towards its intrinsic value of ~ 21.3?GPa.     

Influence of barium borosilicate glass on microstructure and dielectric properties of (Ba,Ca)(Zr,Ti)O3 ceramics

Barium borosilicate (BBS) glass was added as a sintering aid to (Ba_0.7Ca_0.3)TiO₃-Ba(Ti_0.8Zr_0.2)O₃ (BCZT) ceramics at levels from 2 to 15?wt%, yielding enhanced densification. The addition of BBS also induced changes in phase composition, from predominantly tetragonal to orthorhombic at room temperature. It is shown that the changes in phase content are caused by a shift of the orthorhombic to tetragonal phase transformation from below room temperature to ≈50?°C. An additional high temperature transition around 120?°C was also identified. These observations are interpreted in terms of the development of chemical heterogeneity associated with the redistribution of dopant elements (particularly Zr and Ca) through the liquid phase during sintering. The relative permittivity and electric field-induced polarisation values were generally degraded by the presence of the glass phase, but a reduction in ferroelectric hysteresis and improved densification behaviour have potential benefits in dielectric energy storage applications.     

The effect of nano‐sized silicate layers from montmorillonite on glass transition,dynamic mechanical,and thermal degradation properties of segmented polyurethane

The glass transition temperature of the hard‐segment phase and the storage modulus of segmented polyurethane increased substantially in the presence of a small amount of tethered nano‐sized layered silicates from montmorillonite compared with their pristine state (by 44°C and by 2.8‐fold, respectively). Furthermore, the heat resistance and degradation kinetics of these montmorillonite/polyurethane nanocomposites were enhanced, as shown by thermogravimetric analysis. In particular, a 40°C increase in the degradation temperature and a 14% increase in the degradation activation energy occurred in polyurethane containing 1 wt % trihydroxyl swelling agent‐modified montmorillonite compared to that of the pristine polyurethane. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1741–1748, 2002     

Phase stability,thermo-physical properties and thermal cycling behavior of plasma-sprayed CTZ,CTZ/YSZ thermal barrier coatings

ZrO₂ co-stabilized by CeO₂ and TiO₂ with stable, nontransformable tetragonal phase has attracted much attention as a potential material for thermal barrier coatings (TBCs) applied at temperatures >?1200?°C. In this study, ZrO₂ co-stabilized by 15?mol% CeO₂ and 5?mol% TiO₂ (CTZ) and CTZ/YSZ (zirconia stabilized by 7.4?wt% Y₂O₃) double-ceramic-layer TBCs were respectively deposited by atmospheric plasma spraying. The microstructures, phase stability and thermo-physical properties of the CTZ coating were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric-differential scanning calorimeter (TG-DSC), laser pulses and dilatometry. Results showed that the CTZ coating with single tetragonal phase was more stable than the YSZ coating during isothermal heat-treatment at 1300?°C. The CTZ coating had a lower thermal conductivity than that of YSZ coating, decreasing from 0.89?W?m^?1 K^?1 to 0.76?W?m^?1 K^?1 with increasing temperature from room temperature to 1000?°C. The thermal expansion coefficients were in the range of 8.98?×?10^?6 K^?1 – 9.88 ×10^?6 K^?1. Samples were also thermally cycled at 1000?°C and 1100?°C. Failure of the TBCs was mainly a result of the thermal expansion mismatch between CTZ coating and superallloy substrate, the severe coating sintering and the reduction-oxidation of cerium oxide. The thermal durability of the TBCs at 1000?°C can be effectively enhanced by using a YSZ buffer layer, while the thermal cycling life of CTZ/YSZ double-ceramic-layer TBCs at 1100?°C was still unsatisfying. The thermal shock resistance of the CTZ coating should be improved; otherwise the promising properties of CTZ could not be transferred to a well-functioning coating.     

Structure and thermal stability of polysaccharide fractions extracted from the ultrasonic irradiated and cold alkali pretreated bamboo

Polysaccharide fractions were extracted from partially delignified bamboo (Neosinocalamus affinis) culms pretreated with ultrasonic irradiation for varied times and cold sodium hydroxide/urea solution, and their structure and thermal stability were comparatively characterized. In this case, ball‐milled bamboo culms were treated with ultrasonic irradiation for varied times (0, 5, 15, and 25 min), dissolved with 7% sodium hydroxide/12% urea solution at −12°C, and then extracted with ethanol and dioxane to obtain partially delignified solid fractions. Subsequently, the solid fractions were subjected to be extracted with dimethyl sulfoxide followed by precipitation in ethanol and yielded the polysaccharide fractions. Sugar analysis indicated that the total sugar content increased from 60.63% in the polysaccharide fraction prepared without ultrasonic irradiation to 81.26% in the polysaccharide fraction prepared with an ultrasonic irradiation time of 25 min. Glucose (∼ 50–55%) was the major sugar component, and xylose (∼ 41–44%) was the second major sugar in polysaccharide fractions in all cases. Spectroscopy (FTIR, ¹H‐NMR, ¹³C‐NMR, and HSQC) analysis suggested that the polysaccharide fractions were mainly composed of (1→4)‐linked α‐D ‐glucan from amylose and (1→4)‐linked β‐D ‐xylan attached with minor amounts of branched sugars from hemicelluloses. In addition, thermal analysis showed that the main degradation stage of the polysaccharide fractions occurred between 210 and 320°C. Compared to the polysaccharide fraction prepared without ultrasonic irradiation, the polysaccharide fraction prepared with ultrasonic irradiation had a slightly lower thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Physical,thermal, optical,structural and nuclear radiation shielding properties of Sm2O3 reinforced borotellurite glasses

To observe direct effect of samarium (III) oxide reinforcement on physical, thermal, optical, structural and nuclear radiation attenuation properties, a broad-range experimental and numerical investigations were performed with a group of novel borotellurite glasses. FTIR spectra of powdered samples were taken at 250-4000 cm^-1. The transmittance and absorption characteristics, optical band gaps, and Urbach energies were measured. The glass transition temperatures, crystallization temperatures and melting temperature values of the samples were determined. Nuclear radiation shielding properties have been determined for gamma-ray, neutrons and heavy charged particles. The lowest transmittance and highest absorbance were reported for the TBVS1.5 sample with highest Sm₂O₃ additive. In addition, obtained results from the nuclear radiation shielding calculations have showed that TBVS1.5 sample has superior nuclear radiation shielding properties against gamma-ray, neutron and heavy charged particles. The increasing Sm2O3 additive has visibly improved the nuclear radiation attenuation properties by keeping other material properties within usable limits.     

Influence of viscosity and composition of alkali borosilicate lead-free frit on its reaction with hematite,and the color control of red overglaze enamels

Inspired by the ion diffusion at the interface between the red glaze and glaze layers, which was confirmed by the study of overglaze painting on porcelain test pieces, we developed frits with compositions in which a lime glaze was systematically added to a lead-free multicomponent alkali borosilicate glass frit. When the mixed powder of the frit and hematite was heat-treated, the excessive reaction with hematite was suppressed as the lime glaze content increased, due to the increase of the frit viscosity. The dissolution of hematite was suppressed in the sample with the same viscosity at a higher heat treatment temperature, i.e., with a higher lime glaze content, confirming that the composition of the frit strongly affects the dissolution of hematite. We attempted to improve the chroma of lime-glaze-added samples, and the highest chroma in this system was achieved by adjusting the amount of initial hematite and heat treatment temperature.     

Effects of zirconium carbide content on thermal stability and ablation properties of carbon/phenolic composites

Ceramic particles were utilized to improve thermal stability and ablation properties of carbon/phenolic (C/Ph) composites. In this study, zirconium carbide (ZrC) modified C/Ph composites were fabricated by vacuum impregnation method, and effects of ZrC content on thermal stability and ablation properties were investigated by thermogravimetry analysis and plasma wind tunnel test. Moreover, morphological characterization was carried out using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Experimental results showed that increasing ZrC content could lead to an evident increase in char yield, but an observable reduction in linear ablation rates and back-face temperatures because of the formation of ZrO₂ layer on the ablation surface. The work provided an effective way to improve thermal stability and ablation properties of C/Ph composites.     

玻璃纤维理化性能对生产过程影响的研究

玻璃纤维物理性能主要包括硬挺度、断裂强度、可燃物含量、含水率、线密度等一系列指标,对玻璃纤维理化性能进行充分的了解,能够有利于稳定生产、拍导生产、质量控制。本文首先分析了玻璃纤维的物理化学特点,其次,从质量控制、稳定和指导生产三个方面就玻璃纤维理化性能对生产过程影响进行了深入的研究,提出了自己的思考和观点,具有一定的参考价值。     

Impact of bismuth oxide on the structure,optical features and ligand field parameters of borosilicate glasses doped with nickel oxide

Understanding the impact of bismuth cations on the optical properties of borosilicate glass is significant for manipulating borate glass applications. In this paper, the influence of bismuth cations on both structural and optical properties of borosilicate glass doped with NiO was investigated. Different glass samples, containing different amounts of Bi₂O₃ and a constant amount of NiO, were prepared and studied. Infrared (IR) analysis was carried out to study the internal structure within the investigated glass samples. Optical absorption studies were performed to investigate the impact of Bi₂O₃ content on optical properties of the BiBaNiB-glasses. Astonishingly, with Bi₂O₃ addition, an absorption band at 380 nm has appeared. Moreover, this band is overlapped with the Urbach edge; which regularly produced an artificial edge-like feature at ~450 nm. A detailed deconvolution protocol has been implemented for an appropriate understanding of these spectra and unraveling the hidden Urbach edge. Optical band gap energy, linear and nonlinear refractive index for each BiBaNiB sample were calculated. Furthermore, the metallization criterion was calculated to examine the metallic or insulating nature of the BiBaNiB-glasses. The values of the nonlinear third-order susceptibility and nonlinear refractive index were increased with Bi₂O₃ doping. The BiBaNiB-glasses exhibited outstanding stability and optical band gap than the pristine glass sample, which makes it possible for practical applications.     

Cation field-strength effects on ion irradiation-induced mechanical property changes of borosilicate glass structures

We examine the impact of the glass network-modifier cation field strength (CFS) on ion irradiation-induced mechanical property changes in borosilicate (BS) glasses for the ternary M₂O–B₂O₃–SiO₂ systems with M = {Na, K, Rb} and the quaternary [0.5M₍₂₎O–0.5Na₂O]–B₂O₃–SiO₂ systems with M = {Li, Na, K, Rb Mg, Ca, Sr, Ba}. ¹¹B nuclear magnetic resonance (NMR) experiments on the as-prepared BS glasses yielded the fractional population of four-coordinated B species (B^[4]) out of all {B^[3], B^[4]} groups in the glass network, along with the fraction of B^[4]–O–Si linkages out of all B^[4]–O–Si/B bonds. Both parameters correlated linearly with the (average) CFS of the M⁺ and/or {M⁽²⁾⁺, Na⁺} cations. Both the nanoindentation-derived hardness and Young's modulus values of the glasses reduced upon their irradiation by Si²⁺ ions, with the property deterioration decreasing linearly with increasing M^z+ CFS, that is, for higher M^z+⋅⋅⋅O interaction strength. The irradiation damage of the glass network also increased linearly with the fraction of B^[4]–O–Si linkages, which are the second weakest in the structure after the M^z+⋅⋅⋅O bonds. Our results underscore the advantages of employing BS glasses with high-CFS cations for enhancing the radiation resistance for nuclear waste storage.     

Effect of boron oxide on mechanical and thermal properties of bioactive glass coatings for biomedical applications

Bioactive glass coatings can improve the osteo integration of metallic implants with the host tissue, thereby increasing their lifespan and overall success rate. However, complex composition-structure-property relations in phosphosilicate-based bioactive glasses make experimental determination of these relations and related composition design of bioactive coatings challenging. By applying molecular dynamics (MD)-based atomistic simulations with recently developed effective potentials, this work addresses the challenge by using a material genome approach to obtain the composition and structure effects on various key properties for bioactive coating applications. A series of potential bioactive glass compositions were studied and the composition effects on the mechanical and thermal properties that are critical to these bioactive glasses as a coating to metallic implants were calculated. Particularly, by varying the level of B₂O₃ to SiO₂ substitutions, the effect of composition on various key properties was elucidated. It was found that by using cation in a 1 to 1 ratio (BO_3/2 to SiO₂) instead of the commonly used substitutions (B₂O₃ to SiO₂), the composition effect can be more clearly expressed and, hence, recommended in future composition designs. Together with careful structural analysis, the origin of property changes can be elucidated. The atomistic computer simulation-based approach is, thus, an effective way to guide future bioactive glass designs for bioactive coatings and other applications.     

Influence of the addition of carbonated hydroxyapatite and selenium dioxide on mechanical properties and in vitro bioactivity of borosilicate inert glass

Five nanocomposite samples containing different percentages of carbonated hydroxyapatite (CHA), selenium dioxide (SeO₂) and inert glass (IG) have been prepared using high-energy ball milling method with the aim of improving the in vitro bioactivity of these nanocomposites. Fourier transform infrared (FTIR) spectroscopy along with X-ray diffraction (XRD) technique was applied on both nanopowders and the sintered nanocomposites to record the structural changes and examine the resultant sintered phases. Mechanical properties were measured by ultrasonic non-destructive technique. In order to assess the bioactivity of the sintered specimens, they were soaked in simulated body fluid for 14 days and then, they were investigated by FTIR and scanning electron microscopy (SEM). Both FTIR and XRD spectra showed that the glasses encouraged the partial HA decomposition to tricalcium phosphate (TCP) and calcium silicate (CaSiO₃) phases. The formation of the latter phase along with the remainder HA contents was responsible for good bioactivity and appropriate mechanical properties of the investigated nanocomposites. The successive addition of selenium dioxide to these nanocomposites led to further improvement of their bioactivity without any recorded changes in the mechanical properties. Based on the abovementioned results, the prepared nanocomposites can be used in various tissue-engineering applications.