Science Session -Previous years

Water jet cutting and surface abrasion, creative application with particular reference to glass. Vanessa Cutler,Welsh School of Glass, Swansea Metropolitan University

The development of the research at Swansea Metropolitan University looking at the application of waterjet cutting for the visual artist has shown that the technology is a suitable tool for creative industries especially within glass and ceramics. The work carried out initially on a two-axis machine shows the creative application of glass across the three areas of glass design, hot studio, kiln and architecture. In past couple of years the research has developed expanding the parameters of cutting further with the use with two and five axis machines and surface abrasion alongside cutting. Thus allowing a more three dimensional investigation into the properties of the machine and the material. The time spent has enabled exploitation of the technology alongside the material. This investigation offers that opportunity of further development glass, machine and the combining of techniques and processes that have initiated through the initial research (Cutler, 2006). Thus giving insight into the role of this intelligent technology and how through interaction and understanding the manipulation of processes can produce the unexpected outside the established boundaries of current visual art practice. The purpose to extend limits and gain insight to further possible creative application, by challenging what has gone before. By working with both two and five axis machines it is allowing industry and education take another look at the process and its future applications within the creative section. Through a series of case studies of working with both glass and bone china using the cutting and water jet surface abrasion the creative potential and application can be assessed to it viability to the creative sector and how it might then be expanded to more fragile materials. This paper enables contributors to the research and development of the technology to observe how a glassmaker has viewed the integration of art and technology. The computer exerting itself in a field that has remained relatively unchanged without due cause, mechanization has slowly integrated itself into the glass studio. However some may see this as a step towards remote making, with more emphasis on technology and process than the creative idea or the value of the craftsmanship. The assumption may be that the role of technology may be viewed as anti craft rather than to enhance. The combination of the technology with other glass processes can allow manipulation of something that would have been unobtainable. Work created through no means other than those processes combined together, leads to results that open up yet more possibilities to display how art and technology integrate through craftsmanship. The intention is to deliver a paper and display artworks that suggest how glass and its artistic development along with industry collaborate development of the role of the material and the technology to become more integrated.

Crystallisation of Cr-doped soda-lime-silica glasses as a possible route to recycling


Prof J M Parker, University of Sheffield

This project investigated the behaviour of Cr3+ ions during the crystallisation of green soda-lime-silica glass. The absence of a viable method for removing chromium from these glasses precludes the majority being recycled in the UK, where there is limited green glass production.  A high level of segregation of Cr3+ during crystallisation might allow its removal.
The glasses were crystallised, and the different phases analysed using X-ray diffraction. The presence of Cr3+ in the crystal phase should cause peak shifts. Cristobalite formed first on the surface followed by devitrite growing into the bulk of the glass. Chromium segregated into the glass matrix, not the crystal structures, a result confirmed by SEM elemental mapping.
Scanning electron and optical microscopy were used to measure the temperature dependence of crystal growth rates. From these activation energies were calculated and the impact Cr had on growth was assessed.  The activation energies for devitrite growth increased with increasing Cr content.  A Kissinger plot using DTA data was also used to calculate activation energies and gave similar results.
Based on its composition the resulting glass matrix after crystallisation was expected to have a dramatically reduced chemical durability and to be Cr rich.  A large drop in chemical durability was found; however the fraction of the Cr leached out was low.  We will examine the potential of the technique in recycling.

Borate vs. Silicate glasses: Why are they so different ?
A Wright

Most attempts to explain the difference between the properties of borate and silicate glasses, {i.e. the so-called borate (or boron oxide) anomaly} have focussed on the change in co-ordination number of some of the boron atoms from three to four. The present paper discusses the origin of this co-ordination number change at a fundamental level, together with the important role played, both by superstructural units and by network-modifying cations, in determining borate glass properties. In addition, the Krogh-Moe – Griscom superstructural unit model for the structure of borate glasses is updated in line with more modern experimental data, and used to account for the way in which the fraction of 4-fold co-ordinated boron atoms in lithium, sodium and silver borate glasses varies with composition. It is concluded that, far from being anomalous, the properties of vitreous B2O3 and binary M2O-B2O3 glasses are entirely consistent with respect to the electron configuration and bonding of the boron atoms and to the presence of superstructural units. Extrema in the variation of some properties with composition are due to the interplay between opposing factors. The only remaining question concerns the origin and relative magnitudes of the stabilisation energies for the various superstructural unit species.

The structural evolution in alkali borosilicate glasses with increasing ZrO2 content
Andrew Conelly , University of Sheffield

The presence of large quantities of ZrO2 in certain high level nuclear waste streams presents a significant problem due to the relatively low solubility of ZrO2 in oxide glasses. The solubility of oxides such as ZrO2 is highly correlated with the structural role the cation takes and changes it makes in the bulk glass structure of the glass. Here molecular dynamic modelling was used to give insights into the structure of 2 sodium-lithium borosilicate glasses with ZrO2 additions. Analysis of the changes in bulk glass structure with ZrO2 additions has not been studied in detail before. This work shows that addition of ZrO2 changes the coordination of boron and the polymerisation of the glass network due to the requirement for one mole of alkali oxide for charge compensation. The change in boron coordination is shown to be non-linear with addition of ZrO2. For the first time a possible method for predicting the solubility limits of elements within glasses from MD simulations has been put forward.

 

B2O3 Continued – A High-Resolution 17O Double-Rotation NMR Study
Diane Holland

We have previously used 11B double-rotation (DOR) NMR to derive the B-O-B bond angle distribution in vitreous B2O3 (v-B2O3) and demonstrate that the boroxol ring is planar. In the work presented here, we have successfully used high resolution 17O DOR NMR spectra of v-B2O3 to demonstrate that there are two distinct oxygen sites and their 17O NMR parameters have been determined.  These sites are assigned to oxygen atoms in the boroxol ring [B3O6] and in the non-boroxol [BO3] groups which share oxygen with the ring boron atoms. This assignment is based on the similarity of all of their 17O parameters with those found by DFT calculation for caesium enneaborate, Cs2O∙9B2O3, which has two boroxol rings in its structure. The boroxol ring oxygens have a more positive chemical shift, a larger shift anisotropy and a smaller electric field gradient than non ring oxygens. The relative proportions of the two sites in v-B2O3 are ~ 1:1, as expected if all three boron atoms in the boroxol ring are each connected to one oxygen in a linking [BO3] group and there are very few [BO3]-[BO3] linkages.  We see no evidence for a third oxygen site such as has been reported in an earlier study of v-B2O3.



Effects of matrix and crystalline phase in analysis of opal glass by X-ray fluorescence spectrometry
Mehrdad Dahrazma, Sepide Jam Toos Co., Iran

In this paper source of errors were investigated in analysis of opal glass by fluorescence X-ray method. This type of glass analysis is usually faced with numerous problems; because of presence of crystalline phases in opal glass and complex matrix. By help of a fundamental parameter model effect of matrix on analysis of multi component material were investigated. Also αi,j was calculated based on primary and secondary fluorescence. The obtained results show that we could not neglect the primary and secondary fluorescence in analyses of F NaCa Ba Si Al Zr and Fe and by applying this model, satisfactory results were obtained for analyses of opal glass. The accuracy was investigated by using SRM -91. Also results of XRD analysis revealed the reason for deviation of oxidized analysis of opal glass.

Effects of MgO on Silicate Glass Properties and Structure
William C. LaCourse Alfred University

The structural role of MgO in silicate glasses is not well understood. While it is considered a network modifier, it's effect on chemical, mechanical and transport properties does not fully justify such a simple classification. The present paper reviews published information and provides new data regarding the complicated role of MgO on structure and it's effect on properties. It will be shown that several properties of soda-lime silicates and other commercial glasses can be significantly altered and often improved by suitable adjustments of the MgO content.

Everything you always wanted to know about the structure of sodium silicate glass but were afraid to ask
Gavin Mountjoy University of Kent

 

Sodium silicate is a classic glass-forming system.  It provides a chemically simple archetype of a modified random network glass, and is an important reference system due to the widespread use of soda in glass-making.  Surprisingly, little X-ray diffraction data has been reported for sodium silicate glasses, and no diffraction data is reported for sodium metasilicate glass, limiting the validation of previous computer models of these glasses.  We present new molecular dynamics models for sodium silicate glasses and compare them with new diffraction data.  Inspection of the models provides unprecedented details of the modified random network model.  The idea of separate silica network and modifier cation regions is a simplification.  In particular, sodium has a great impact on both non-bridging oxygens and bridging oxygens.  The latter is a good way to explain the notable effect of sodium in reducing chemical durability.  

 

Determination of diffusion characteristics of ion exchanged float glass by use of a Surface Ablation Cell (SAC)
Stefan Karlsson, Växjö University

Ion exchange of glass has been studied for several decades and ion exchange strengthened glasses are presently used in special applications e.g. aircraft windshields, displays and spectacle lenses. Chemically strengthened float glass will most likely find applications in future building and interior constructions where strength, design and shape prevent thermal strengthening. The presented work studies ion exchange of a specific critical area e.g. around a drilled hole. Ion exchange follows Fick’s law of diffusion and by determining concentration profiles of ion exchanged float glasses, it is possible to calculate the diffusion coefficients and activation energy for diffusion. Traditionally the treated float glass is immersed into a molten salt bath ion exchanging both sides of float glass. The approach presented here means applying a salt paste to a single side of the float glass. The concentration profiles are determined using a surface ablation cell (SAC), a laboratory equipment allowing the continuous removal of the material from a float or any flat glass surface by slow controlled isotropic dissolution. Analysis of the etching solution from the micron sizes layers on the surface of the float glass gives absolute values of specific compounds. The potassium diffusion coefficients of two different KNO3/KCl mixtures are ranging between 1.4x10^-11 to 6.8x10^-11 cm2/s. The activation energies of the two different salt mixtures were calculated to 111 kJ/mol and 100 kJ/mol, respectively. The Surface Ablation Cell (SAC) has been developed through collaborative work within Technical Committee 2 (Chemical Durability and Analysis) and Technical Committee 19 (Glass Surface Diagnostics) within International Commission on Glass. The present work confirms that the procedure and equipment are very cheap and easy to use and gives data similar to those gained by much more expensive equipment.

 



 

Introducing  X-rays to ISIS.
Emma Barney* and Alan Soper, STFC

Diffraction is arguably the single most important probe of the structure of glass, but nevertheless it has its limitations. One of the major difficulties is that the results are not element specific; a single diffraction experiment on a glass, or other amorphous material, contains contributions from all element pairs.  When these contributions to the correlation function overlap it is not possible to uniquely separate them.  However, multiple diffraction measurements using different radiations greatly assist in the deconvolution of overlapping contributions due to the contrast in scattering amplitude.   The X-ray scattering power of elements vary with atomic number, whereas the scattering power for neutrons depends on the interaction of the neutron with the nucleus, and varies haphazardly across the periodic table. Therefore, for elements with similar atomic number, the scattering amplitude of X-rays will be similar, but it is possible that there will be a strong difference in the neutron scattering amplitude.  Utilising this contrast gives additional information with which to separate interatomic correlations, and allows a more reliable structural model to be developed.
A silver source X-ray diffractometer has been added to the suite of instruments available to the ISIS disordered materials community.   This facility has been provided with the aim of routinely measuring high quality laboratory X-ray diffraction data in conjunction with neutron diffraction results.   This will allow users of the Nimrod, GEM and Sandals neutron diffractometers to exploit the complementarities of X-rays and neutrons and extract the maximum information possible from their data. 
This talk will present both structure factor and correlation function information for a range of samples, including liquids, oxide glasses, metallic glasses and crystalline materials, all of which will be used to illustrate the benefits of using both X-ray and neutron diffraction data in understanding the structure of amorphous materials. The data presented will clearly show both the quality and reliability of the data which can be collected on the diffractometer. However, in addition to making accurate measurements of the samples, careful data reduction is of paramount importance.  There are a wide a range of effects which make the processing of X-ray data problematic, so to fully exploit the X-ray data a new data reduction program, GudrunX, has been developed.  All of the data presented will have been processed using this software, and the power of the program in dealing with difficult data will be demonstrated. 
The commissioning of the X-ray diffractometer is now at an advanced stage and it is ready to be used by the glass community.  Further information on how to request access to it will be given. 

 

 

Tin Borate Glass Structure By Neutron Diffraction And NMR
Prof Alex C. Hannon, STFC

We are interested in studying the structure of tin borate glasses as part of a larger investigation of lone pair ions in network glasses, with the ultimate aim of being able to control the charge distribution and influence non-linear optical properties. Neutron diffraction has been used to investigate the structure for borate glasses with a wide range of SnO content, revealing sample preparation difficulties not apparent in previous 11B and 119Sn NMR studies. The fraction, N4, of borons which are 4-coordinated has an unusual behaviour, with a relatively low maximum value of 0.32, which occurs at ca. 50 mol.% SnO. This behaviour is discussed from the point of view of the microscopic factors which affect the number of 4-coordinated borons in the glass. 

 

Influence of limestone grain size on glass homogeneity
Marie-Hélène Chopinet

The lack of homogeneity in a glass is characterized by the occurrence of layers of different chemical compositions and densities. When starting materials relevant for the synthesis of soda-lime silicate glasses are melted in a crucible, silica- and calcium-enrichments are observed at the top and at the bottom of the melt respectively [1, 2]. This behaviour may be due to the occurrence of several reaction pathways. In this respect, an interesting observation is that the grain size of limestone is found to be an important parameter influencing the level of glass homogeneity. The reasons for this have been studied here using systematic differential thermal analysis and thermogravimetric analysis on unary, binary and ternary combinations of the relevant starting materials. The experiments showed that, in presence of limestone of small grain size (< 200 micrometers), sodium carbonate disappears before the temperature at which it is observed to interact with silica in the CaO - free system. We infer that this is most probably due to production of a mixed carbonate liquid, which subsequently reacts with silica to spontaneously yield a homogeneous silicate melt. A characteristic of this probable mixed carbonate (assumed to be close to the composition CaNa2(CO3)2) is its density of 2.54g/cm3, close to that of the silicates and of silica itself. On the contrary, coarse limestone decomposes to CaO (and CO2), which is slowly incorporated in the sodium silicate liquid formed when sodium carbonate interacts with silica. The much higher density of CaO (3.35 g/cm3) and of calcium silicates could explain the tendency for CaO concentrations to be greatest towards the base of melting crucibles. [1] R.L. Tiede & F.V. Tooley, Effect of temperature on homogenising rate of Na2O CaO SiO2 glass, J.Amer. Ceram. Soc., 1945, 28(2) 42 [2] F.V. Tooley & R.L. Tiede, Influence of batch mixing time and batch grain size on homogeneity of a soda-lime silica glass, J. Amer. Ceram. Soc, 1946, 29(7), 197-199



 

Mass transfer of a rising bubble in molten glass

F. Pigeonneau Surface du Verre et Interface, UMR 125 CNRS/Saint-Gobain, Aubervilliers France

The mass transfer around a rising bubble is studied within the field of glass melting processes where the oxidation-reduction reaction of iron oxides is taken into account. The dimensionless mass transfer coefficient, Sherwood number, is determined as a function of the Péclet number based on the terminal rising velocity of the bubble. Two different techniques are used: the first based on the boundary layer theory and the second using a finite element method.

In order to take into account the oxidation-reduction reaction in a unified framework, a modified Péclet number is found as a function of two dimensionless numbers linked to the equilibrium constant of the chemical reaction and the glass oxygen saturation. The Sherwood number, taking into account the chemical reactions, increases with iron content as well as with glass reduction.

The behaviour of an isolated rising bubble in molten glass is examined both experimentally and numerically. The theoretical model to describe bubble shrinkage is based on the preceding results. Bubble size as a function of time is presented where two stages are observed: at short times, the bubble shrinks; at longer times, the bubble size reaches a steady-state value.

A scale analysis is proposed to describe bubble features under a dimensionless form and a characteristic time of shrinkage rate is proposed. The representation of experimental data under this dimensionless form gives a good match at short times of experimental results. Finally, a simple equation to determine bubble size as a function of time is given based on the Sherwood number established under a boundary layer regime.



 

Influence of limestone grain size on glass homogeneity
Marie-Hélène Chopinet

The lack of homogeneity in a glass is characterized by the occurrence of layers of different chemical compositions and densities. When starting materials relevant for the synthesis of soda-lime silicate glasses are melted in a crucible, silica- and calcium-enrichments are observed at the top and at the bottom of the melt respectively [1, 2]. This behaviour may be due to the occurrence of several reaction pathways. In this respect, an interesting observation is that the grain size of limestone is found to be an important parameter influencing the level of glass homogeneity. The reasons for this have been studied here using systematic differential thermal analysis and thermogravimetric analysis on unary, binary and ternary combinations of the relevant starting materials. The experiments showed that, in presence of limestone of small grain size (< 200 micrometers), sodium carbonate disappears before the temperature at which it is observed to interact with silica in the CaO - free system. We infer that this is most probably due to production of a mixed carbonate liquid, which subsequently reacts with silica to spontaneously yield a homogeneous silicate melt. A characteristic of this probable mixed carbonate (assumed to be close to the composition CaNa2(CO3)2) is its density of 2.54g/cm3, close to that of the silicates and of silica itself. On the contrary, coarse limestone decomposes to CaO (and CO2), which is slowly incorporated in the sodium silicate liquid formed when sodium carbonate interacts with silica. The much higher density of CaO (3.35 g/cm3) and of calcium silicates could explain the tendency for CaO concentrations to be greatest towards the base of melting crucibles. [1] R.L. Tiede & F.V. Tooley, Effect of temperature on homogenising rate of Na2O CaO SiO2 glass, J.Amer. Ceram. Soc., 1945, 28(2) 42 [2] F.V. Tooley & R.L. Tiede, Influence of batch mixing time and batch grain size on homogeneity of a soda-lime silica glass, J. Amer. Ceram. Soc, 1946, 29(7), 197-199

 

 

Mass transfer of a rising bubble in molten glass
F. Pigeonneau Surface du Verre et Interface, UMR 125 CNRS/Saint-Gobain, Aubervilliers France

 

The mass transfer around a rising bubble is studied within the field of glass melting processes where the oxidation-reduction reaction of iron oxides is taken into account. The dimensionless mass transfer coefficient, Sherwood number, is determined as a function of the Péclet number based on the terminal rising velocity of the bubble. Two different techniques are used: the first based on the boundary layer theory and the second using a finite element method.

In order to take into account the oxidation-reduction reaction in a unified framework, a modified Péclet number is found as a function of two dimensionless numbers linked to the equilibrium constant of the chemical reaction and the glass oxygen saturation. The Sherwood number, taking into account the chemical reactions, increases with iron content as well as with glass reduction.

The behaviour of an isolated rising bubble in molten glass is examined both experimentally and numerically. The theoretical model to describe bubble shrinkage is based on the preceding results. Bubble size as a function of time is presented where two stages are observed: at short times, the bubble shrinks; at longer times, the bubble size reaches a steady-state value.

A scale analysis is proposed to describe bubble features under a dimensionless form and a characteristic time of shrinkage rate is proposed. The representation of experimental data under this dimensionless form gives a good match at short times of experimental results. Finally, a simple equation to determine bubble size as a function of time is given based on the Sherwood number established under a boundary layer regime.

The near surface mechanical properties of durable and non-durable silicate glasses
Russell J Hand

It is well known that silicate glasses undergo surface hydration. We are using nanoindentation to study the near-surface mechanical properties of a range of silicate glasses that exhibit differing degrees of hydration. Significant degradation in the near surface modulus and hardness can be seen on hydration. The results will be discussed in the context of models for surface coatings with different mechanical properties.

 

The suitability of using photoelastic stress measurement equipment and four point bend test of fused recycled bottle glass
Tyra Oseng, Swansea Metropolitan University

 

A systematic study has been undertaken into the suitability of fused recycled bottled glass as a material for architectural applications. When post-consumer bottle glass is crushed and fused at a low temperature, residual stress, anecdotally known as incompatibility, can cause the fused material to unexpectedly crack or shatter. Systematic experiments have been undertaken in order to investigate the possibility of creating a stable fused material with low residual stress. The paper considers the use of a strain measurement system based on photoelasticity, where excess residual stress in the fused material can be quantitatively determined with a proposed stress threshold. Mechanical test results are also presented for a four point bending measurement, where process parameters such as kiln schedule, temperature, colour development and crushed-glass fragment sizes are assessed. The conclusion is a proposed new material for architectural applications derived from a lower energy

Modified Iron Phosphate Glasses for Waste Immobilization
Paul A. BinghamUniversity of Sheffield

Iron phosphate glasses can exhibit high aqueous durability and low melting temperatures - a combination that supports their potential use as host materials for waste vitrification. A substantial proportion of research into iron phosphate glasses has dealt with formulations in the ternary P2O5 - Fe2O3 - FeO system, and particularly the familiar 60 P2O5 - 40 Fe2O3 (mol %) composition. Debate continues into the structure of even these relatively simple glasses, and under some conditions they can have limited thermal stability and a limited useful glass forming region. Selective addition of R+, R2+, R3+ and / or R4+ cations to the P2O5 - Fe2O3 - FeO system can allow tailoring of properties by extending the glass forming region; by further improving chemical durability; and by increasing thermal stability. Such additives may also be present in certain wastes being immobilized, therefore their effects on structure / property relations should be studied in detail. The structure of modified iron phosphate glasses has been studied using an array of techniques including X-Ray Absorption spectroscopy and Mossbauer spectroscopy and the results are here discussed in the context of measured physical properties and potential applications of some of the glasses developed.

 

 

Novel Glass Wasteforms for Advanced Fuel Cycle Initiative
S. K. Sundaram,Northwest National LaboratoryRichland

Novel glass wasteforms are proposed for two waste streams:  1) iodine (I) waste stream from UREX+1 aqueous process and 2) salt waste stream containing fission products including lanthanides, alkalis, alkaline earths, and iodine plus trace transuranic (TRU) impurities left in the K, Li, Na chloride salt from electrochemical separation process.  Halides have been incorporated into glasses in many forms, e.g., halides, halophosphates, halosilicates, halotellurites, and chalcohalides.  These glasses range from purely ionic glasses (simply halides) to mixed bonds (complex halides with other glass formers).  Most of these glasses have been investigated for fundamental glass formation, electrical/optical properties, and energy applications.  There has been limited work on phosphohalide wasteform development.  Based on various reported systems, as much as 60% or more of halides could easily be incorporated into this family of glasses and some of these glasses have shown good chemical durability.  Halide glasses can also accommodate mixtures of fluorides, chlorides, and iodides, if the halide waste stream could not be separated into the individual halides.  For iodine waste stream, two glass systems, Ge-S-I and As2Se3-AgI, are explored.  TeO2-X2O-XCl system, where X = Li, K, and NA, is studied for salt waste stream.  Glass formation and chemical durability data will be presented.      

 

EFFICIENT FREQUENCY CONVERSION IN OXIDE GLASSES
Evelyne Fargin,ICMCB Pessac

EFFICIENT FREQUENCY CONVERSION IN OXIDE GLASSES AND GLASS NANOCOMPOSITES E. Fargin, T. Cardinal CNRS, Université de Bordeaux, ICMCB, 87 av. Dr. A. Schweitzer, Pessac F-33608, France Université de Bordeaux, CREMEM, Talence, F-33405, France M. Dussauze, V. Rodriguez ISM, UMR 5803 CNRS, Université Bordeaux, 351 cours de la Libération, Talence, F- 33405, France. A.Royon, M. Bellec, L. Canioni Centre de Physique Moléculaire Optique et Hertzienne, Université de Bordeaux, 351 cours de la libération, 33405 Talence, France ,Ji Yeon Choi, Martin Richardson Townes Laser Institute, The College of Optics and Photonics, University of Central Florida, Orlando Florida 32816-2700 USA Kathleen Richardson School of Materials Science and Engineering, Clemson University, COMSET, 161 Sirrine Hall, Box 340971, Clemson, SC 29634, USA S. Lotarev, V. Sigaev Mendeleev University of Chemical Technology of Russia, Miusskaya pl. 9, 125190 Moscow, Russia E.I. kamitsos, G. Mountrichas Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Ave., 116 35 Athens, Greece Transparent materials exhibiting NLO properties are key materials for the development of integrated optics (waveguides, gratings, data storage…). For instance, it would be a great advantage to utilize transparent Glasses and Glass nanocomposites as low-cost materials exhibiting second harmonic generation (SHG) for photonic devices. One of the main issues for succeeding is the control of crystallization. Glasses containing d0 and d10 transition ions have been widely investigated. Nucleation and crystallization processes have been conducted in phosphate and silicates matrices containing large amount of niobium oxide to ensure the precipitation of one unique ferroelectric phase in the Nb2O5 - NaNbO3 solid solution. Silver ions presence in the glass compositions increases the crystallization rate and allows controlling spatial homogeneity and size of precipitated dielectric nanoparticules. Different approaches to obtain SHG have been conducted. Electro-poling has been performed on glass nanocomposites to induce efficient Second Harmonic Generation (SHG). We also propose a novel approach to patterning a periodic structure of depleted and undepleted zones in glass in order to enable efficient quasi-phase matching and thus enable efficient second-order nonlinear effects. The poling structure has been investigated in a silver-containing glass by femtosecond direct laser patterning a linear periodic array, where silver clusters form in the irradiation regions. The application of a DC electric field through electro-poling is expected to induce a periodic structure of the second order nonlinearity efficiency of the material due to the differences in ion mobility of the irradiated and unirradiated zones. We further aim to show the unique characteristics of these structures using SHG measurements. Key words: photonic glasses, glass nanocomposites, non linear optics, electro-poling, Second Harmonic Generation, Direct Laser Writing

 

 

Effect of tribological glass ceramics behavior on artificial human
Hanaa EL Kazazz, Mahmoud Abd El Zaher, . Moanes Abd El Hakam Azoz

 

Effect of tribological glass ceramics behavior on artificial human Joints fabrication Dr. Hanaa EL Kazazz1, Dr. Mahmoud Abd El Zaher2, Dr. Moanes Abd El Hakam Azoz3 1- Ass. Prof., Faculty of Applied Arts, Helwan Uni., glass Department, Orman, Giza, Cairo. 2- Lecturer, Faculty of Applied Arts, Helwan Uni., Industrial design Dep. 3- Ass. Prof., Glass Res. Dept., National Research Center. Key words 1=Glass ceramic 2=Human joints 3=Heat treatment 4=Hardness 5=Wear- Corrosion. Abstract: An experimental research was carried out to produce some bioglass samples Serve as a substitute human joint. Four batches were produced to choose the suitable one; batches chemical compositions were wt &#1642; 1- SiO2 45, CaO 24.5, P2O5 6 , Na2O 24.5,Al2O3 --, MgO --. 2- SiO2 40, CaO 24.5, P2O5 6 , Na2O 24.5,Al2O3 5, MgO --. 3- SiO2 40, CaO 24.5, P2O5 6 , Na2O 24.5,Al2O3 --, MgO 5. 4- SiO2 40, CaO 24.5, P2O5 6 , Na2O 24.5,B2O3 5. four samples from each batch were produced; melting temperature ranging from (1400-1450&#9702;C) for two hours, the 16 samples were subjected to heat treatment at 700&#9702;C for four hours, 850&#9702;C for three hours and 1000&#9702;C for three hours. The samples’ Hardness were measured by Knoop, The Hardness were ranging from 502-840. All samples were conducted formerly to dry and wet (3% NaCl) friction test against hardened alloy steel disc (62SiMnCr4-HRC60+1) at normal load of 12.21Nand 0.126 m\sec rubbing velocity to measure the wear rate and latterly to chemical corrosion test to detect the corrosion resistance in each sample. Test results showed that samples no. 4 produced from batch 4 had the lowest value of friction coefficient that reached 0.048. As for wear rate, sample (B) produced from batch no. 2 represented maximum values of wear rate (3.827 X 10-12, 1.234 X 10-12 m3 \m sliding) in normal atmosphere and corrosive environment (3% NaCl) respectively, while the sample (D3) produced from batch 4 represented minimum values of wear rate (1.816 X 10-12, 0.605 X 10-12 m3 \m sliding) at the same conditions. Consequently; the wear rate displayed remarkable increase with decreasing of the heat treatment temperature and vice versa. The wear rate in normal atmosphere was almost about triple time in corrosive environment (3% NaCl).16 glass ceramic samples were subjected to (3% NaCl) and V-1 characteristic curves were conducted through polarization and galvanic testing. 16 samples of glass ceramic proved to attain considerable high resistance to corrosion.

The structure-property relationship in borate, silicate and borosilicate glasses
Natalia M. Vedishcheva
Institute of Silicate Chemistry of the Russian Academy of Sciences

Since the structure of glasses determines their properties, establishing the structure-property relationship is of considerable practical significance. All of the models, known to the authors, consider glass structure as a network of different basic structural units with varying numbers of bridging oxygen atoms, such as B(n) or Si(n), and completely neglect the role of the network-modifying cations. Therefore, these models allow neither properties of glasses comprising different modifying oxides (e.g. various alkali borate glasses) or different glass-forming oxides (borate, silicate or borosilicate glasses) to be described with equal reliability, nor various well-known features in the structure of the short-range order to be explained. The suggested concept of chemical structure of glasses enables the above problems to be successfully solved, since this approach takes into account the presence of network-modifying cations in glasses and considers structural changes in terms of the Gibbs energy of a given system. As the approach allows both the structure and a variety of glass properties to be calculated, the structure-property relationship is established quantitatively. The approach also explains the relationship between two levels in the glass structure (the short- and intermediate-range order) and shows which of them determines properties of glasses. This will be illustrated by the example of glasses in the systems M2O-B2O3, M2O-SiO2, MO-SiO2 and M2O-B2O3-SiO2.



The structure-property relationship in borate, silicate and borosilicate glasses
Natalia M. Vedishcheva
Institute of Silicate Chemistry of the Russian Academy of Sciences

Since the structure of glasses determines their properties, establishing the structure-property relationship is of considerable practical significance. All of the models, known to the authors, consider glass structure as a network of different basic structural units with varying numbers of bridging oxygen atoms, such as B(n) or Si(n), and completely neglect the role of the network-modifying cations. Therefore, these models allow neither properties of glasses comprising different modifying oxides (e.g. various alkali borate glasses) or different glass-forming oxides (borate, silicate or borosilicate glasses) to be described with equal reliability, nor various well-known features in the structure of the short-range order to be explained. The suggested concept of chemical structure of glasses enables the above problems to be successfully solved, since this approach takes into account the presence of network-modifying cations in glasses and considers structural changes in terms of the Gibbs energy of a given system. As the approach allows both the structure and a variety of glass properties to be calculated, the structure-property relationship is established quantitatively. The approach also explains the relationship between two levels in the glass structure (the short- and intermediate-range order) and shows which of them determines properties of glasses. This will be illustrated by the example of glasses in the systems M2O-B2O3, M2O-SiO2, MO-SiO2 and M2O-B2O3-SiO2.



 

Microwave processing of glass for waste immobilisation
Martin C. Stennett

Microwave (or dielectric) heating is recognised as a fast, clean and economical preparation route for a wide range of inorganic solids. The microwave spectrum lies in the frequency range 0.3 to 300 GHz which is mainly used for communication purposes, although a narrow frequency window centred at 2.45 GHz is allowed for microwave heating purposes. Materials in general fall into three categories: microwave reflectors, transmitters, and absorbers. A key requirement for microwave heating is that one or more of the major constituents of the batch must be a microwave absorber and couple strongly to the microwave field at room temperature. Microwave heating has a number of key advantages over conventional heating. Microwave heating is a rapid process and unlike conventional heating the charge is heated from the inside out. This minimises undesirable decomposition, oxidation / reduction, loss of volatile materials, and other kinetically slow processes which can occur during conventional melting. In this work, the microwave processing of different transition metal phosphate glass compositions, with potential as immobilisation matrices for radioactive wastes, has been studied. Chemically homogeneous glasses have been successfully prepared in all systems by microwave heating over timescales of the order of several minutes. The resulting glasses have been compared with conventionally melted glasses using a range of characterisation techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, infra red (IR) and X-ray absorption spectroscopy (XAS).