تزجيج

(تم التحويل من التزجيج)
تجربة تزجيج.

التزجيج Vitrification، هو تحويل مادة ما إلى زجاج،[1] مادة لابورية غير متبلورة. في عملية إنتاج الخزف، يؤدي التزجيج إلى جعل الخزف غير نافذ للماء.[2]

عادة ما يتم التزجيج بتسخين المواد حتى تتحول إلى سائل، ثم تبريد السائل، وعادة ما يتم التبريد سريعاً، ومن ثم يمر السائل بمرحلة تحول الزجاج ليشكل مادة مزججة. كذلك، فإن بعض التفاعلات الكيميائية قد تسفر عن تكون الزجاج.

تستخدم عملية التزجيج في صناعة الفخار، الزجاج، وبعض أنواع الأغذية، لكن هناك الكثير من التطبيقات الأخرى، مثل تزجيج السائل المضاد للتجميد في الحفظ بالتجميد.

الخزف

Vitrification is the progressive partial fusion of a clay, or of a body, as a result of a firing process. As vitrification proceeds, the proportion of glassy bond increases and the apparent porosity of the fired product becomes progressively lower.[3][4] Vitreous bodies have open porosity, and may be either opaque or translucent. In this context, "zero porosity" may be defined as less than 1% water absorption. However, various standard procedures define the conditions of water absorption.[5][6][7] An example is by ASTM, who state "The term vitreous generally signifies less than 0.5% absorption, except for floor and wall tile and low-voltage electrical insulators, which are considered vitreous up to 3% water absorption."[8]

Pottery can be made impermeable to water by glazing or by vitrification. Porcelain, bone china, and sanitaryware are examples of vitrified pottery, and are impermeable even without glaze. Stoneware may be vitrified or semi-vitrified; the latter type would not be impermeable without glaze.[3][9][10]

التطبيقات

When sucrose is cooled slowly it results in crystal sugar (or rock candy), but when cooled rapidly it can form syrupy cotton candy (candy/fairy floss).

Vitrification can also occur in a liquid such as water, usually through very rapid cooling or the introduction of agents that suppress the formation of ice crystals. This is in contrast to ordinary freezing which results in ice crystal formation. Vitrification is used in cryo-electron microscopy to cool samples so quickly that they can be imaged with an electron microscope without damage.[11][12] In 2017, the Nobel prize for Chemistry was awarded for the development of this technology, which can be used to image objects such as proteins or virus particles.[13]

Ordinary soda–lime glass, used in windows and drinking containers, is created by the addition of sodium carbonate and lime (calcium oxide) to silicon dioxide. Without these additives, silicon dioxide would require very high temperature to obtain a melt, and subsequently (with slow cooling) a glass.

Vitrification is used in disposal and long-term storage of nuclear waste or other hazardous wastes.[14] Waste is mixed with glass-forming chemicals in a furnace to form molten glass that then solidifies in canisters, thereby immobilizing the waste. The final waste form resembles obsidian and is a non-leaching, durable material that effectively traps the waste inside. It is widely assumed that such waste can be stored for relatively long periods in this form without concern for air or groundwater contamination. Bulk vitrification uses electrodes to melt soil and wastes where they lie buried. The hardened waste may then be disinterred with less danger of widespread contamination. According to the Pacific Northwest National Labs, "Vitrification locks dangerous materials into a stable glass form that will last for thousands of years."[15]

Vitrification in cryopreservation

Vitrification in cryopreservation is used to preserve, for example, human egg cells (oocytes) (in oocyte cryopreservation) and embryos (in embryo cryopreservation). It prevents ice crystal formation and is a very fast process: -23,000 °C/min.

Currently, vitrification techniques have only been applied to brains (neurovitrification) by Alcor and to the upper body by the Cryonics Institute, but research is in progress by both organizations to apply vitrification to the whole body.

Many woody plants living in polar regions naturally vitrify their cells to survive the cold. Some can survive immersion in liquid nitrogen and liquid helium.[16] Vitrification can also be used to preserve endangered plant species and their seeds. For example, recalcitrant seeds are considered hard to preserve. Plant vitrification solution (PVS), one of application of vitrification, has successfully preserved Nymphaea caerulea seeds.[17]

Additives used in cryobiology or produced naturally by organisms living in polar regions are called cryoprotectants.

Tg (Glass transition temperature) of sugars and plant vitrification solutions[17]
Formula Tg (Mid, °C)
1M sucrose -30.9
1M glucose -41.3
1M trehalose -68.0
50% sucrose + 50% glycerol (PVS3) -90.7
50% sucrose + 50% (ethylene glycol) EG -101.1
50% sucrose + 50% (propylene glycol) PG -89.1
75% sucrose + 25% glycerol -81.2
75% sucrose + 25% EG -80.7
75% sucrose + 25% PG -63.6
25% sucrose + 75% glycerol -91.3
25% sucrose + 75% EG -108.9
25% sucrose + 75% PG -98.0

انظر أيضاً

المصادر

  1. ^ A.K. Varshneya. Fundamentals of inorganic glasses. Sheffield: Society of Glass Technology, 2006.
  2. ^ Arthur Dodd & David Murfin. Dictionary of Ceramics; 3rd edition. The Institute of Minerals, 1994.
  3. ^ أ ب خطأ استشهاد: وسم <ref> غير صحيح؛ لا نص تم توفيره للمراجع المسماة doddmurfin
  4. ^ 'Role Of Accessory Minerals On The Vitrification Of Whiteware Compositions.' N.M.Ghoneim; E.H.Sallam; D.M. Ebrahim. Ceram.Int. 16. No.1. 1990.
  5. ^ Whitewares: Production, Testing and Quality Control. William Ryan & Charles Radford. Institute of Materials, 1997
  6. ^ 'Methods Of Extending The Narrow Vitrification Range Of Clays.' E.V. Glass & Ceramics 36, (8), 450, 1979.
  7. ^ 'Control Of Optimum Vitrification In Vitreous And Porcelain Bodies.' E.Signorini. Ceram.Inf. 26. No.301. 1991
  8. ^ ASTM C242-01. 'Standard Terminology Of Ceramic Whitewares and Related Products'.
  9. ^ 'Body Builders.' J.Ahmed. Asian Ceramics. June 2014 [استشهاد ناقص]
  10. ^ 'An Introduction To The Technology Of Pottery.' Paul Rado, Institute of Ceramics. 1988.
  11. ^ Dubochet, J.; McDowall, A.W. (December 1981). "Vitrification of pure water for electron microscopy". Journal of Microscopy. 124 (3): 3–4. doi:10.1111/j.1365-2818.1981.tb02483.x.
  12. ^ Dubochet, J. (March 2012). "Cryo-EM-the first thirty years". Journal of Microscopy. 245 (3): 221–224. doi:10.1111/j.1365-2818.2011.03569.x. PMID 22457877. S2CID 30869924.
  13. ^ "Nobel Prize in Chemistry Awarded for Cryo-Electron Microscopy". The New York Times. October 4, 2017. Retrieved 4 October 2017.
  14. ^ Ojovan, Michael I.; Lee, William E. (2011). "Glassy wasteforms for nuclear waste immobilization". Metallurgical and Materials Transactions A. 42 (4): 837–851. Bibcode:2011MMTA...42..837O. doi:10.1007/s11661-010-0525-7.
  15. ^ "Waste Form Release Calculations for the 2005 Integrated Disposal Facility Performance Assessment" (PDF). PNNL-15198. Pacific Northwest National Laboratory. July 2005. Retrieved 2006-11-08.
  16. ^ Strimbeck, GR; Schaberg, PG; Fossdal, CG; Schröder, WP; Kjellsen, TD (2015). "Extreme low temperature tolerance in woody plants". Frontiers in Plant Science. 6: 884. Bibcode:2015FrPS....6..884S. doi:10.3389/fpls.2015.00884. PMC 4609829. PMID 26539202.
  17. ^ أ ب Lee, Chung-Hao (2016). Cryopreservation of seeds of blue waterlily (Nymphaea caerulea) using glutathione adding plant vitrification solution, PVS+ / 埃及藍睡蓮種子的冷凍保存 — 使用添加穀胱甘肽的植物抗凍配方 (PDF) (in English). National Tsing Hua University. OCLC 1009363362. Archived from the original (PDF) on 2024-11-26. Retrieved 2023-01-09.{{cite book}}: CS1 maint: unrecognized language (link)
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