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| Posted By: Warren Wolf from Dr.WW Wolf Services | ||
| July 17, 2004 | 1:00 PM | Strength of Glass |
| Glass is an exceptional strong but brittle material which limits or discourages many of its uses. Improving the strength of glass to remove the brittle limitations would improve the value proposition for glass products but also contribute to significantly reducing wasted energy that results in flawed or broken operations in hot end forming. This is a problem across all sectors in the glass indsutry. A big challenge is could new R&D create a different glass surface during forming by modifying that hot pristine surface? There have been attempts but no sustained work to achieve this. With new knowledge of glass physics and chemistry are new approaches possible that could achieve this end goal of a stronger glass with less wasted energy in lost products as well as new value propositions for glass products? | ||
| Replied By: Sheila Sweval | ||
| 25 - Mar - 2005 | 4:04 AM | Strength of Glass |
| Hi Warren, just checking this out, my first post. I had an interesting conversation with Simon Rekhson about the strength of glass spheres. There is some work being done with very small glass bubbles used to store hydrogen which might be applied to battery technology. Simon says that the spheres are extremely strong and able to contain the gas at very high pressures, under tension. My reply was that spheres are an inherently strong shape, eg, portholes on ships and submarines are always round for that reason. We make a 17" diameter sphere for a company called Benthos, who uses them in underwater instrument applications like tsunami detectors. They almost bounce off the cullet can! | ||
| Replied By: Michael Greenman from Glass Manufacturing Industry | ||
| 13 - Apr - 2006 | 8:33 AM | Strength of Glass |
| Sheila is right about the "inherent strength" of the sphere! Industry interest is in modifying the surface structure of glass so that, in any shape or form, it exhibits greater strength - reduced brittleness. As part of an industry effort to develop stronger glass, the GMIC will be announcing its second "Strength in Glass" University contest this June: available to University-level students globally, this contest with cash prizes will reward the most innovative and practical products and applications described that would be possible IF glass exhibited 50 times its current tensile strength. This event will be followed by a further contest to be announced in 2007, with a substantial cash prize to be awarded to the individual or group actually demonstrating such increased strength. | ||
| Replied By: Charles Merivale from Amalgamet Canada | ||
| 17 - Apr - 2006 | 12:00 PM | Strength of Glass and Lithium |
| Lithium has the smallest ionic radius and the highest ionic potential of any solid. The combination of the strongest chemical bond and the smallest atom offer unmatched opportunities to increase strength which await exploitation by glassmakers. In application, these properties should improve glass fibre strength reducing downtime from strand breakage during processing, or enable light weighting of containers or even auto glass. I have not seen any work to either prove or disprove these theories and would be delighted to hear from anyone who has done any research in this area. Of course, this improved strength would be on top of the many other processing and property improvements enabled by lithium including its fluxing capability which lowers fuel demand. Reduced viscosity induced by lithium might also help overcome some hot end forming issues mentioned by Dr. Wolf. | ||
| Replied By: Thomas Seward from Alfred University | ||
| 20 - Apr - 2006 | 1:02 PM | Lithium in glass |
| This will probably not be news to very many of you, but this posting is to remind you that in the 1960s and 1970s Corning Incorporated developed ion-exchange streangthenable glasses containing mixed alkalis, lithium and sodium in particular. The glass products (mostly oththalmic) were strengthened in combined sodium-potassium salt baths. The potassium-for-sodium exchange provided good compressive strength and the sodium-for-lithium exchange gave added depth to the compression layer. | ||
| Replied By: Charles Merivale from Amalgamet Canada | ||
| 21 - Apr - 2006 | 10:15 AM | Ion Exchange Glass |
| Further to Dr. Seward's comments, and as most readers are no doubt aware, PPG's ion exchange glass uses this mechanism of replacing the smaller lithium ion with sodium to produce a very strong glass with high surface tension which is very suitable particularly for demanding aerospace applications. Of course this is also an expensive processing step that may not be workable for all end uses requiring extra strength from glass. The ion exchange process is very valid but is not the nature of the increased strength from lithium which I was referring to in my previous posting. I have found little research in this area but lithium's "smallest ionic radius and highest ionic potential" of any solid suggests strength at the atomic level which cannot be matched by any other element. Ceramicists have long reported lithium improves "chip resistance", a manifestation of the same process of strengthening. The many reports of a "brighter glass" from lithium also have to be seen as another demonstration of a stronger exterior; less light is absorbed by the lithium containing surface, more is reflected. We know lithium enables a stronger exterior, consistently shown to improve acid resistance. Is lithium only in the exterior? It seems more likely it is equally dispersed throughout the body. As far as I know, no one has evaluated this but these are all demonstrations of the same property of improved strength from lithium. Any further insights into this are invited and eagerly awaited. | ||