Glass Ceramics

Presentation on Glass Ceramics

1. PRESENTED BY:- Yash Johri

2. GLASS…..?

3. History….?

4. COMPOSITION…?

5. Constituents…?

6. TYPES OF GLASSES

7. Soda-lime-silica glass SiO2 (silica) 70% Na2O (sodium oxide)12% CaO (calcium oxide) 8% MgO (magnesium oxide) 3% Al2O3 ( aluminium oxide) 1% Commercial glass is colourless Additional chemicals have to be added to produce different colours of glass such as green, blue or brown glass .

8. Lead-potash-silica glass It is made by using lead oxide instead of calcium oxide, and potassium oxide instead of all or most of the sodium oxide High refractive index Relatively soft surface High electrical resistivity Radiation protection (higher lead oxide contents typically 65%absorb gamma rays and other forms of harmful radiation)

9. Borosilicate glass Silica (70-80%) and Boric oxide (7-13%) with smaller amounts of the Alkalis (sodium and potassium oxides) and Aluminium oxide. ovenware and other heat-resisting ware (Pyrex )

10. PROCESS OF GLASS MAKING

11. Pot Process..? The manufactured of high quality glass such as optical and mirror glass & small quantities of specialty glass. Hazard of hand shoveling & filling of the pots. Optical and specialty glasses contain heavy metals (lead, barium and manganese )

12. Tank Process…? Permits enclosed &continuous feeding of bath ingredient (reduced dust exposure) Refractory blocks and bricks used in the construction of the furnaces and tanks contain free silica .

13. CERAMICS

14. Bonded Clay Ceramics Made from natural clays and mixtures of clays and added crystalline ceramics. These include: Whitewares Structural Clay Products Refractory Ceramics

15. Whitewares Crockery Floor and wall tiles Sanitary-ware Electrical porcelain Decorative ceramics

16. Refractories Firebricks for furnaces and ovens. Have high Silicon or Aluminium oxide content . Brick products are used in the manufacturing plant for iron and steel, non-ferrous metals, glass, cements, ceramics, energy conversion, petroleum, and chemical industries .

17. ©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e” Properties of Ceramic Materials High hardness, electrical and thermal insulating, chemical stability, and high melting temperatures Brittle, virtually no ductility - can cause problems in both processing and performance of ceramic products Some ceramics are translucent, window glass (based on silica) being the clearest example

18. ©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e” Three Basic Categories of Ceramics Traditional ceramics ‑ clay products such as pottery and bricks, common abrasives, and cement New ceramics ‑ more recently developed ceramics based on oxides, carbides, etc., and generally possessing mechanical or physical properties superior or unique compared to traditional ceramics Glasses ‑ based primarily on silica and distinguished by their noncrystalline structure

19. ©2002 John Wiley & Sons, Inc. M. P. Groover, “Fundamentals of Modern Manufacturing 2/e” Raw Materials for Traditional Ceramics Mineral silicates, such as clays of various compositions, and silica , such as quartz, are among the most abundant substances in nature and constitute the principal raw materials for traditional ceramics Another important raw material for traditional ceramics is alumina These solid crystalline compounds have been formed and mixed in the earth’s crust over billions of years by complex geological processes

20. Choice is yours………..??