Soda-lime Silicate Float Glass Research Articles

On the structure and properties of hydrothermally toughened soda–lime silicate float glass

On the structure and properties of hydrothermally toughened soda–lime silicate float glass

Enhancing mechanical endurance of chemical-tempered thin soda-lime silicate float glass by ion exchange

The aim of this study is to determine the mechanical properties differences in between the air and tin surfaces of thin soda-lime silicate float glasses that subjected to ion exchange using KNO3 salt bath. The ion exchange process was carried out at different times and temperatures. Chemically tempered glasses were investigated by means of compressive stress (CS), microhardness measurements, cracking probability, fractographic analysis, and flexural strength. The relationship among these properties was also discussed. The Weibull distributions of the samples were determined for a better understanding of the strength results. The AFM was used to determine the surface roughness. The weight of glass samples was increased gradually with increasing ion exchange time and temperature due to the inter-diffusion of K+–Na+ ions. The fracture load of chemically strengthened glass with ion exchange at 435 °C-8 h showed an increase of ~ 4.4 times that of untreated glass (raw glass), and it was selected as the optimum process conditions. The number of broken pieces was increased by increasing flexural strength, and smaller pieces were obtained with a great deal of branching. The air side always has greater compressive stress than the tin side. The maximum hardness value was reached with ion exchange at 435 °C for 12 h on a tin surface was 8.25 GPa with an increase of ~ 18% with respect to the raw glass. The crack resistance of chemically tempered glasses showed an increase in the range of 410–1290% and 241–1895% for air and tin surfaces, respectively. According to the AFM analysis, surface roughness of the samples after ion exchange did not change dramatically. SEM-EDS analysis revealed that the surface potassium concentration and diffusion depth increase with temperature.

Effect of Na contamination on the chemical strengthening of soda-lime silicate float glass by ion-exchange in molten potassium nitrate

Commercial soda-lime silicate float glasses are chemically strengthened at 450 °C for 4 and 24 h in molten potassium nitrate containing small but controlled amount of NaNO3. The ion-exchange efficiency is determined from the measurement of surface compressive stress, potassium penetration and flexural strength. Chemical strengthening remains efficient also for NaNO3 additions up to 0.5 wt% (equivalent to ~1350 ppm Na) and the glass performance being identical to those obtained in pure KNO3, with no significative difference between “tin” and “air” side. For larger Na contamination residual stress and strength are reduced by an amount of about 25%.

Mechanical and optical properties of SiO2 thin films deposited on glass

The optical and mechanical properties of amorphous SiO2 films deposited on soda-lime silicate float glass by reactive RF magnetron sputtering at room temperature were investigated in dependence of the process pressure. The densities of the films are strongly influenced by the process pressure and vary between 2.38 and 1.91 g cm−3 as the pressure changes from 0.27 to 1.33 Pa. The refractive indices of the films shift between 1.52 and 1.37, while the residual compressive stresses in the deposited films vary in the range from 440 to 1 MPa. Hardness and reduced elastic modulus values follow the same trend and decline with the increase of process pressure from 8.5 to 2.2 GPa and from 73.7 to 30.9 GPa, respectively. The abrasive wear resistance decreases with the density of the films.

Synthesis and characterization of the mechanical and optical properties of Ca-Si-O-N thin films deposited by RF magnetron sputtering

Ca-Si-O-N thin films were deposited on commercial soda-lime silicate float glass, silica wafers and sapphire substrates by RF magnetron co-sputtering from Ca and Si targets in an Ar/N2/O2 gas mixture. Chemical composition, surface morphology, hardness, reduced elastic modulus and optical properties of the films were investigated using X-ray photoelectron spectroscopy, scanning electron microscopy, nanoindentation, and spectroscopic ellipsometry. It was found that the composition of the films can be controlled by the Ca target power, predominantly, and by the reactive gas flow. Thin films in the Ca-Si-O-N system are composed of N and Ca contents up to 31eq. % and 60eq. %, respectively. The films thickness ranges from 600 to 3000nm and increases with increasing Ca target power. The films surface roughness varied between 2 and 12nm, and approximately decreases with increasing power of Ca target. The hardness (4–12GPa) and reduced elastic modulus (65–145GPa) of the films increase and decrease with the N and Ca contents respectively. The refractive index (1.56–1.82) is primarily dictated by the N content. The properties are compared with findings for bulk glasses in the Ca-Si-(Al)-O-N systems, and it is concluded that Ca-Si-O-N thin films have higher values of hardness, elastic modulus and refractive index than bulk glasses of similar composition.

Influence of salt bath calcium contamination on soda lime silicate glass chemical strengthening

Soda lime silicate float glass was ion exchanged in potassium nitrate baths systematically contaminated with calcium nitrate up to 0.01mol%. The results show that surface compression and flexural strength are dramatically depressed if the treatment is carried out in salt containing calcium nitrate in excess of 0.0015mol%, this being related to more limited sodium-potassium exchange on the surface. The presence of calcium in the salt accounts for a “blocking” effect of the conventional Na-K exchange which is shown to be thermodynamically less favoured than Na-Ca one, especially at higher temperature.

Chemical Strengthening of Soda Lime Silicate Float Glass: Effect of Small Differences in the KNO3 Bath

Six slightly different KNO3 baths were considered in this work, for the chemical strengthening of soda lime silicate glass. Five of these were commercially available pure KNO3 salts for industrial or laboratory use and one was a salt from an unknown source that had been already used for at least 1000 h in Na–K ion exchange. Various amounts of sodium — the main impurity — calcium, and magnesium were measured in the six salts together with other more limited contaminants. Different strengthening effects associated with clearly dissimilar ion exchange efficiency were measured on glass treated in the different melts. The presence of Na — major impurity — in the salt was revealed to be not a critical aspect, at least up to concentration of about 0.5 wt%. Instead, the “blocking” effect caused by the presence of Ca and Mg in the KNO3 bath (also in amounts of few tens of ppm) is shown to be a major issue.

Analysis of the surface structure of soda lime silicate glass after chemical strengthening in different KNO3 salt baths

This paper deals with the physico-chemical and mechanical properties of soda lime silicate float glass treated in KNO3 baths with different purity levels. The potassium concentration profile in the surface layers was measured by EDXS and correlated with the residual stress frozen in the material, which was determined by a procedure based on the measurement of the strengthened sample curvature deriving from progressively etching one of its surfaces. This allowed pointing out a significant influence of the used salt. In order to better understand the phenomena and mechanisms underlying the surface equilibrium conditions, micro-Raman measurements were also performed on the glass surface in the aim to investigate the variation of the glass microstructure after ion-exchange in the different salt baths.

Transparent armour materials

The ballistic performance of transparent ceramic and glass materials was investigated. Various types of layered sandwich composites were compared from the ballistic resistance viewpoint. Layered sandwiches from soda-lime silicate float glass and also sandwiches with sapphire top layer were prepared. Their ballistic resistances against two types of 7.62 mm caliber armour-piercing (AP) ammunition of protection level 3 according to NATO Standardization Agreement STANAG 4569 were investigated. For the ballistic performance assessment depth of penetration (DOP) test method and ballistic mass efficiency of sandwich (BME S) criterion were used. From economical, technological, optical and ballistic point of view as optimal solution sandwich structure consisting of sapphire front-face layer, float glass internal layers and polycarbonate backing layer was found. Specific solution is shown in the article.

Configuration of twins in glass‐embedded silver nanoparticles of various origin

AbstractStructural characterization using high resolution electron microscopy and diffractogram analysis of silver nanoparticles embedded in glass by various routes of fabrication was aimed at revealing the characteristic features of twin faults occuring in such particles. Nearly spherical silver nanoparticles well below 10 nm size embedded in commercial soda‐lime silicate float glass have been fabricated either by silver/sodium ion exchange or by Ag+ ion implantation. Twinned nanoparticles, besides single crystalline species, have frequently been observed for both fabrication routes, mainly at sizes above 5 nm, but also at smaller sizes, even around 1 nm. The variety of particle forms comprises single crystalline particles of nearly cuboctahedron shape, particles containing single twin faults, and multiply twinned particles containing parallel twin lamellae, or cyclic twinned segments arranged around axes of fivefold symmetry. Parallel twinning is distinctly favoured by ion implantation whereas cyclic twinning preferably occurs upon ion exchange processing. Regardless of single or repeated twinning, parallel or cyclic twin arrangement, one may classify simple twin faults of regular atomic configuration and compound twin faults whose irregular configuration consists of additional planar defects like associated stacking faults or secondary twin faults. Besides, a particular superstructure composed of parallel twin lamellae of only three atomic layers thickness is observed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Fracture behavior of engineered stress profile soda lime silicate glass

Multi-step ion-exchange processing can produce complex stress profiles in glass surfaces, which can result in increased fracture strength, reduced strength dispersion, flaw tolerance and multiple cracking behavior. Glass displaying this set of properties is termed engineered stress profile (ESP) glass. Treatments at 400–450 °C in molten KNO 3 and NaNO 3 salt baths were used to create residual stresses in the surface of soda lime silicate float glass. Stress profiles were measured using optical stress birefringence, allowing derivation of apparent fracture toughness curves and prediction of crack stability over a range of flaw sizes. Specimens were tested in the four-point bend configuration to determine fracture strength and to study the multiple cracking which results from crack growth stabilization. The results were compared to predictions from the fracture toughness curves, in terms of the strength dispersion and crack stability criteria. Indented specimens were tested to determine the response of the glass to contact damage.