ENGR_220_Ch12.ppt_Callister8e_RK_1

ENGR_220_Ch12.ppt_Callister8e_RK_1 - 1 Chapter 12 29...

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Unformatted text preview: 10/21/11 1 Chapter 12 - 29 ANNOUNCEMENTS - 1 ¡ Week 6 Recitations: Problems 14.2, 14.5, 14.8, 14.14 14.26, 14.28, 14.29 (Polymers) ¡ Quiz #3 on Ch. 5 and/or 12 (Diffusion and/or Ceramics) ¡ Midterm #2: Tuesday, November 8, 8:00-8:50 am , Main Auditorium Accommodations : LeBow 348; 8:00-9:15 (1.5X) or 8:00-9:40 am (2X) Coverage: Chapters 5, 12, 14, plus a smattering from Chapters 1, 2, 3 & 4 TA Help Session #2: Thu, November 3, 5:00 - ~7:30 pm, CAT 061 Chapter 12 - 30 ANNOUNCEMENTS - 2 ¡ Final Exam: Friday, December 9, 3:30-5:30 pm , Location TBA Accommodations : LeBow 348; 3:30-6:30 (1.5X) or 3:30-7:30 pm (2X) Coverage: Cumulative, but with an emphasis on material covered since Midterm #2. Part of 1 Q likely a “bonus” part … possible to score >100% No early exams for individual convenience … term isn’t over until the end of Finals week … 10/21/11 2 Chapter 12 - 31 Amorphous Silica - Silica Glasses L Silica Glasses- amorphous SiO 2 : Si 4+ and O 2- not in well-ordered lattice … significant randomness Charge balanced by H + (to form OH- ) at “dangling” bonds L very high surface area > 200 m 2 /g SiO 2 is quite stable, therefore unreactive: L makes good catalyst support Add network modifiers (CaO, Na 2 O) to form sodium-silicate glass : L cations incorporated into/modify SiO 4 4- network L lower T m and viscosity Adapted from Fig. 12.11, Callister & Rethwisch 8e. Chapter 12 - 32 Silica Glass L Dense form of amorphous silica: Charge imbalance corrected with “ counter cations ” such as Na + Borosilicate glass is the Pyrex ® glass used in labs or as cookware: L Better temperature stability & less brittle than sodium glass 10/21/11 2 Chapter 12 - 31 Amorphous Silica - Silica Glasses L Silica Glasses- amorphous SiO 2 : Si 4+ and O 2- not in well-ordered lattice … significant randomness Charge balanced by H + (to form OH- ) at “dangling” bonds L very high surface area > 200 m 2 /g SiO 2 is quite stable, therefore unreactive: L makes good catalyst support...
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This note was uploaded on 12/16/2011 for the course ENGR 220 taught by Professor Barsoum during the Spring '08 term at Drexel.

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ENGR_220_Ch12.ppt_Callister8e_RK_1 - 1 Chapter 12 29...

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