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Glasses as engineering materials. A review

Enlarge Font  Decrease Font Released Date:2011-01-31   From:glassonweb   View Time:217
Glass products have applications in design engineering and they can solve many special problems. This materials can work in situations in which plastics and metals would fail and need to be part of designer’s repertoire. In some situations, by using of th
Glass products have applications in design engineering and they can solve many special problems. This materials can work in situations in which plastics and metals would fail and need to be part of designer’s repertoire. In some situations, by using of these materials, some difficult problems would be solved. This paper contains a number of chapters as it follows: a brief about ceramics family, a short history of glass, a brief about physics and the technology of glass fabrication, recently developed glasses with special destinations, testing methods and news about glass parts processing (grinding, waterjet processing, laser cutting, Nano-imprint lithography, etc). The last chapter of this review paper contain some strategic lines of glass usage in industry and estimations about the future of glass development.
Article highlights

1. The ceramics family

Cermets and ceramics are becoming the tool materials for the present and future, by using the cemented carbides at wood working tools (as saw blades ,cutting wheels ) the wear was reduced significant. Coated  cemented carbides displaced the high speed steel for cutting tools and also high production press dies use the cemented carbide tooling. Ceramics are taking a lot of high temperature machine tasks, are substrates for computer chips and are used for prosthetic devices. Glasses and carbon products have applications in design engineering and they can solve many special problems.
2. Brief history of glass. Past and present of glass
Is not exactly known when, where, or how humans first learned to make glass. The legends tells us that a Phoenician sailor (by other historians, a Roman sailor), cooking the evening meal on a beach, set the pots on top of stones of natron (a naturally mixture of sodium carbonate decahydrate, sodium bicarbonate along with small quantities of household salt). As the cooking fire heated both these stones and the sand below, a unknown liquid began to flow and that was the origin of manmade glass.
3. Brief about physics of glass. How is made
The mechanical and physical properties of glasses are essentially determined by their composition, but a general view can be done:
  1. glasses are harder than metals;
  2. glasses have tensile strength in range 24 to 69 MPa;
  3. glasses are brittle and have low ductility;
  4. glasses have a low coefficient of thermal expansion;
  5. glasses have a low coefficient of thermal conductivity;
  6. glasses are good electrical insulators;
  7. glasses are resistant to acids, solvents, chemicals, water and saline water and alkaline solutions;
  8. some glasses can be used at high temperatures (700 oC –soda lime for windows; 1580 oC –fused quartz-silica).
     
4. Advances in glass family development
The glasses family is huge and is in continuous enrichment. Year after year, new types of glass with new properties extend their utilisation domain. The utilisation domain of glass in engineering design have a lot of facets: from banal windows or bottles to antinuclear radiations containers; from architectural and structural glasses to photosensitive glass devices used in machine controls; from food preparation tanks to newest optical fibres. The  enormous variety of existent glass types, rapid development of new and innovative glasses, developments in glass fabrication and development of glass manufacturing processes make that the classification of glasses become extremely hard to do. After the product types, a first classification can be done for the main glass industries, as in table 5. (based on http://www.glassonweb.com/  description-in section Directory )

4.1. Advances in glass and glass ceramics design and manufacture
4.2 Advances in bulk metallic glasses ( BMG) design and manufacture
4.3 Advanced techniques of manufacturing  for glass and glass ceramics

5. Conclusions and strategic lines in glass development
Glass as a material will always exist, but many new applications and manufacturing processes will involve glass in combination with other materials. Optical fibres are currently manufactured with one or more different coating, which are often plastics. With the increasing sophistication of optoelectronic devices, there is an increasing need to combine optical and electronic devices for many applications such as transmission of audio, video and data information. Glasses and ceramics (stand alone or composite with other materials) will find increasing application in biological and medical areas. Materials such as photochromic, electrochromic and thermochromic glasses, which respond to external stimuli, are being developed with various, sometimes unusual, applications. Revolutionary materials, as the flexible ceramic heat shield material (ZircoFlex) are recently developed and fabricated by using a new technology in which the ceramic material is sprayed in the form of thousands of individual 'platelets' onto the surface of the aluminum backing foil (see figure 20). Early applications for ZircoFlexTM foil are coming from the automotive industry, where the foil can be used to protect sensitive components from heat in increasingly crowded engine bays.

Al Gore (former US Vice- president) became the publicly recognizable face of the environmental issue after his Oscar-winning documentary movie An Inconvenient Truth ( 2006). This documentary helped enormous to make the issue of global warming a recognized problem worldwide. The Nobel Peace Prize  (won by Al Gore in 2007) make that  the problem of global warming is once again brought to the forefront. The first impact on glass industry was produced by switching on large scale to compact fluorescent light bulbs (by the replacing of incandescent bulbs 4200+ tons of carbon were offset). Glass industry has successfully reacted to environmental issues by offering a variety of applications to make buildings more energy efficient and ecologically friendly. Today's glass can be practically custom-made to fit into any environmental conditions and offer specific appearances and performance. The latest development in the industry has been the introduction of self-cleaning glass. While progress in the glass industry continues, we can expect glass in the near future that will react to external stimuli, the so-called "smart glasses", offering maximum comfort and excellent energy efficiency inside buildings. Some glass applications also use alternative natural resources to preserve the environment in which we live. The modern glass industry have a huge contribution  through development and the introduction of new energy-efficient glass products and applications, some issues in glass manufacturing and processing still must be addressed in the future. A great  challenge for  the actually and the future  glass industry is to increasingly the contribution for environment preservation. The challenge for researchers and glass industry  is to act for significant decreasing of embedded energy in glass mass unit . There are two possible way for solve this desiderate: a continuously developing of high efficiency furnaces b, continuously developing of new glass compositions, with lower glass  transition temperatures. The synergetic effect of simultaneous applying of both ways could offer a good future for glass industry. Most recent tendencies are to use the green energy (wind and solar) in producing and manufacturing of glasses. The modern glass industry  must increase contribution  through development and the introduction of new energy-efficient glass products and applications, some issues in glass manufacturing and processing still must be addressed in the future.
 
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