In most cases the term is used to denote the processes of purification, separation, and decontamination of aqueous and other ion containing solutions with solid polymeric or mineralic ion exchangers. Interestingly, performing electric field assisted ion exchange, efie, for 10 min produces an ion exchanged layer as deep as conventional strengthening for 4 hours in soda borosilicate glass. There has been little research on ionexchange in glass ceramics. In the past few years, ionexchange iox in glasses has found a renewed interest with. Ion exchange reaction ion exchange reaction ion exchange procedures. This paper proposes a new process to manufacture cover glass which overcomes a strength trade. Ion exchange for glass strengthening sciencedirect. Publishers pdf, also known as version of record includes final page, issue and volume numbers.
Ion exchange pdf created with pdffactory pro trial version 2 ion exchange 1. Processing and properties of ion exchanged glasses jill glass and raj tandon sandia national labs, albuquerque, nm prof. Ion exchange can be used to purify, or polish, returned condensate, removing corrosion products that could cause harmful deposits in boilers. Preparation of ag nanoparticles in glass by double ion exchange process and their application in sers abstract. For cation exchange resins, it is usually between 200 to 500meq per 100 gms. History, introduction, and kinetics of ion exchange materials. An ion is an atom that has either gained or lost an electron and so carries a net charge. Corning gorilla glasstm code 2318 chemical tempering. Typically, the contaminants in the condensate system are particulate iron and copper.
Us5531899a us08467,259 us46725995a us5531899a us 5531899 a us5531899 a us 5531899a us 46725995 a us46725995 a us 46725995a us 5531899 a us5531899 a us 5531899a authority us united states prior art keywords process resin particles solution ion exchange acid groups prior art date 19950606 legal status the legal status is an assumption and is not a legal conclusion. The paper signifies the kinetics involved in the ion exchange process with. Fabrication process the process of ion exchange in glass is based upon a substrate glass, proprietary of leoni. It is a high quality aluminosilicate glass that is chemically strengthened to achieve incredible scratch, breakimpact, and shock resistance. Analytical solution to the nonlinear equations are difficult to find. Exchange of a nacontaining glass in a bath of molten kno.
This process typically increases the strength of the glass by 6 to 8x that of float glass. Much more frequently the exchanger is packed into a tube or column through which the solution is made to flow. Below you will find an easy to follow columntesting guide to help you quickly onto the road to a successful separation process development. Depending on the glass composition, acid concentration, flow. Glass produced using a high ion exchange hie process is stronger and more durable than non hie. The expansion is thus a function of the dol, thickness of the glass sheet and the volume of ions exchanged. All natural waters contain some foreign substances, usually in small amounts. In the ion exchange process, sodium ions are used to coat an exchange medium in. In this study, the effective stress field generated by the invading ions is taken into account for strength evaluation. Samples which were heat treated do not show any significant changes in average strength. The kinetics of the ion exchange process that involve two monovalent z1 ions a and b. Competition for ion exchange sites on a resin can greatly impact a given system. The glass waveguide components fabricated by ion exchange process is characterized by compatibility with optical fibers, potentially low cost, low propagation.
We demonstrate a nonconservation of the total amount of alkali ions in the glass during the ion exchange process. The ion exchange process creates a deep compression layer on the surface of the glass structure, reducing the introduction of flaws once incorporated into the end product and put into service. Influence of kno3 bath composition on ion exchange process of commercial soda lime silicate float glass 309 the effect of ion exchange appears clearer in figure 1, although for samples treated in baths a and b the effect of time is not so evident. Ion exchange is an effective, versatile means of conditioning boiler feedwater. This paper presents a short overview of silicate glass strengthening by exchange of alkali ions in a molten salt, below the glass transition temperature chemical tempering. Silver ions are introduced into glass in silver ion exchange, and reduced into metallic silver in subsequent potassium ion exchange. The mechanical strength of alkalialuminosilicate glasses after ion exchange citation for published version apa. Cations refer to positively charged ions dissolved in the water. Agna ion exchange in sodalime glasses and the formation of small. Only rarely are ion exchangers used in stepwise procedures, in which the resin is mixed into a container of solution and then removed for further treatment. Preparation of ag nanoparticles in glass by double ion. The mechanical strength of alkalialuminosilicate glasses.
Ion exchange is an exchange of ions between two electrolytes or between an electrolyte solution and a complex. Ion exchange fundamentals the selection of an ion exchange process and the degree of demineralisation depend on the application in question and the additional operating and economical conditions. Various exchange active groups, at which ions accumulate, are built into the exchangers. Standard water softeners are cation exchange devices.
Ion exchange uses are not limited to process and boiler water makeup. The mechanical strength of alkalialuminosilicate glasses after ion exchange. Theory and application focuses on the applications, complexities, and theoretical aspects of ion exchange. Since most ion exchange processes are reversible, the ion. Influence of kno bath composition on ion exchange process. Ion exchange just as the name suggests, ion exchange is a water softening method that softens hard water to soft water by exchanging the magnesium and calcium ions with sodium ions. Agna ion exchange in sodalime glasses and the formation.
Recent advances in ion exchanged glass waveguides and. Ionexchange reaction ionexchange procedures britannica. When discussing the ion exchange phenomenon in glass, which is realized through the contact of glass with liquid admixture at sufficiently high temperatures, the main aspects should be specified fig. The exchange at the surface of an alkali ion by a bigger one brings. Silver nanoparticles embedded in glass by ion exchange. Continuous ion exchange processes are usually of the downflow and packedbed column type. Ion exchange and dialysis the removal of ions from solution using resins resin particle and beads ion exchange of monovalent cations. Technical process the ion exchange process is widely used for the removal of hardness as in softening, heavy metals as in waste treatment, radionuclides as from power plants and municipal water feeds removal of nitrates, arsenic, perchlorate, hexavalentchrome and others. The exchange from the surface of an alkali ion in the glass or glassceramic by a bigger one from the bath leads to compressive stress at the surface and because of the concentration distribution to a stress profile through the sample. This glass is highly transparent in the spectral range between 450 nm and 2000 nm, and it is optimized for the exchange of sodium to silver ions.
If the exchanged ions are positive, the exchange material. The ion exchange process isnt new and cornings gorilla glass isnt the only chemically strengthened glass on the market. Arun varshneya and ian spinelli saxon glass technology, inc. The glass plates were immersed in molten bath in porcelain crucible. The chemical strengthening process involves the immersion of an. Ion exchange is always set between ionic species chemical equivalents of the same electric sign. In this study, the effective stress field generated by the. The characterisation of the ion exchange process was mainly performed by utilising a novel analytical equipment. In other words, these two ions which are found in the hard water are contaminated and what the process does is to include exchange. For example, in softening processes, calcium and magnesium ions hardness are exchanged. A typical ion exchange process can take 4120 hours. Electrons are negativelycharged subatomic particles. When the resin capacity is exhausted, it is regenerated.
Sodium ions are supplied from dissolved sodium chloride salt, also called brine. Corning chemically strengthens their glass using a process called ion exchange. Nov 10, 2016 ion exchange is a popular technique for chemically strengthening alkali. Electric field assisted ion exchange also augments the glass strength and makes the glass more damage resistant. Since a cation exchanger must remain electrically neutral during the exchange reaction, all of the exchange. Ion exchange is the process through which ions in solution are transferred to a solid matrix which, in turn releases ions of a different type but of the same polarity. Details of this method may be found in b 16 pages 230232. Cation exchange involves the replacement of the hardness ions with a nonhardness ion. A smaller sampling of test groups was subjected to fractographic analysis to study the effect of ion exchange on fracture features.
The paper defines the ion exchange materials and their types. Watch mindbending demonstrations in the glass age, part 2. In the ion exchange process, sodium ions are used to coat an exchange medium in the softener. Advantages and disadvantages of iron exchange biotech. The solid phase may be a crystalline lattice or a gel. All samples were nished to a thickness of 150 m before the exchange procedure. Modification of float glass surfaces by ion exchange. Ion exchange resins or zeolites have a limited number of ex available, and the total solidphase concentration, q o, is termed the ion exchange capacity. Most water treatment ix processes operate in a continuous mode. Glass parts are immersed in a molten salt solution.
The real secret behind gorilla glass involves a chemical process called an ion exchange. Their deep understanding of the physics of glass surfaces including diffusion, compression, tension, and resistance are likely to yield even more remarkably tough glasses in the future. The ionexchange kinetics is, in general, a nonlinear diffusion probl em. Ion exchange involves dunking a glass sheet into a hot potassium salt bath so that sodium ions in the glass diffuse out and potassium ions diffuse in gy 1. During the time of immersion, the alkali ions from the glass that are close enough to the surface are exchanged for those from the molten salt. But corning has demonstrated the strength of its glass in venues like the consumer electronics show where the company invited people to test come up and see how much pressure it would take to break a piece of its glass.
Shortly after the introduction of the concept of integrated optics, ion exchange in glass. Potassium ions electronically charged particles in the solution migrate into the glass surface. Low breakage strength is the most significant obstacle for a wide application of ultrathin glass, and aluminosilicate glass can be strengthened well after ion exchange. The ion exchange process creates a deep compression layer on the surface of the glass structure, reducing the introduction of flaws. Ion exchange process is established when the solid phase incorporates this solute to its structure without causing a permanent change. The salt, which must contain an alkali metal carbonate, is deposited on the glass article as a mixture with water, or an organic solvent or both. In the exchange process, the ions of the solution to be treated are exchanged with accumulated. In these materials the mechanisms are much more complex than in glasses because of their polyphasic nature. A trip in the history and evolution of ionexchange process. The glass surface and ways of its modification ferdinand trier, munich university of applied science, germany.
Ion exchange provides remarkable damage tolerance and strengthening of glass indentation induced fragment size determined by branching distance central tension, t. Chemically strengthened aluminosilicate thin glass high ion exchange hie thin glass is strong, lightweight and flexible. Ion exchange as a physical process during ion exchange the ions being exchanged are reversibly removed from the wastewater and transferred to the ion exchanger this means that ion exchange is a physical separation process in which the ions exchanged are not chemically altered since the chemical characteristics of the ions. The ion exchange process was performed in a vertical furnace. The ion exchange process is based on a replacement of small alkali ions in the glass with larger alkali ions from a molten salt bath through inter. The current paper briefly summarizes the history of the development of the ion exchange materials. Part of the answer lies in the ionexchange process a scientific treatment of the glass surface to dramatically increase its toughness. Silver nanoparticles embedded in glass are prepared by double ion exchange process. This book discusses the kinetics of fixedbed ion exchange. Water treatment technology water resources engineering civil engineering engc 6305 dr. When applying a photolithographic mask in either the. Silversodium ion exchange is used frequently for incorpora tion of silver in glass to. Jan 27, 2016 ion exchange is a water treatment process commonly used for water softening or demineralization, but it also is used to remove other substances from the water in processes such as dealkalization, deionization, and disinfection. Analysis of strength variation in glass due to ion exchange.
Glass and optical materials division fall meeting cape canaveral, fl nov. Glass strengthening by ion exchange, or chemical tempering, is a process where the original glasses are immerged into a molten alkali salt at a temperature below the glass transition. Glass articles can be strengthened by applying thereto a salt of an alkali metal, different from the alkali metal in the glass, and carrying out an ion exchange at a temperature below the strain point of the glass. The data shows that the ion exchange process caused a statistically significant increase in the strength of the glass rods. Former models of the ion exchange process were based on rough zero. Ion exchange is a unit process in which ions of a given speciesare. During the last few decades, ion exchange materials have evolved from laboratory tool to. Sep 28, 20 how ion exchange can be used to soften hard water. An ion s net charge is negative if it has an extra electron or positive if it lost an electron. Learn more about the ionexchange process in the glass age, part 2.
The principle of this method is based on the weight change in glass samples as a result of the ion exchange process since the ionic weight of potassium 39,0983 u is greater than the sodium. High ionexchange hie chemically strengthened aluminosilicate thin glass high ionexchange hie thin glass is strong, lightweight and flexible. Ion exchange as an engineering process was originally used to improve the surface mechanical properties of structural glass. Strengthening of sodaborosilicate glasses by ion exchange. Ion exchange in glass the changes of glass refraction. Ion exchange is a reversible chemical reaction wherein an ion an atom or a molecule that has lost or gained an electron and thus acquired an electrical charge from a wastewater solution is exchanged for a similarly charged ion attached to an immobile solid particle. Modifying of float glass surface with silver nanoparticles. The silver ions were introduced into the glass network by an isothermal ion exchange with 0. With the twostep ion exchange, uniform nanoparticle clusters over large areas are embedded in glass due to the galvanic replacement reaction and the electrolytic deposition. Rohm and haas ion exchange ion exchange introduction 1 fd sep 2008 ion exchange for dummies an introduction water water is a liquid. Aug 23, 2016 there has been little research on ion exchange in glass ceramics. Modification of float glass surfaces by ion exchange diva portal.
1139 1032 1455 1635 818 564 1260 769 1597 326 789 135 579 791 1565 1347 211 137 326 861 160 339 271 225 1266 217 1133 1407 1073 1057 609 851 1148 844 751 526 767