Transaction Management in Database Management System
Unit 3 corrosion & batteries
1. Unit 3 Corrosion And Batteries Sept. /06 MA/chem/RCET
2.
3.
4. Sept. /06 MA/chem/RCET metal Metal oxide Corrosion ,oxidation Metallurgy ,reduction Higher energy Lower energy
5.
6. Classification Sept. /06 MA/chem/RCET dry wet other oxidation By gases liquid Evolution of H 2 Absorption of O 2
7.
8.
9.
10.
11. Oxidation corrosion Sept. /06 MA/chem/RCET M M n+ + ne - Reaction at metal – metal oxide interface Atmospheric oxygen metal
12.
13.
14.
15. 2. Unstable Sept. /06 MA/chem/RCET metal metal metal Exposed surface O 2 ,air Unstable metal oxide Film formed decomposed + O 2
16. 3. Volatile Sept. /06 MA/chem/RCET metal metal metal Exposed surface O 2 ,air volatile metal oxide Film formed decomposed + O 2
17. 4. Porous Sept. /06 MA/chem/RCET metal metal Exposed surface O 2 ,air porous metal oxide Film formed decomposed + O 2 Further attack through cracks ,pores
18.
19.
20.
21.
22.
23.
24.
25.
26. Evolution of hydrogen Sept. /06 MA/chem/RCET M M n+ + 2e - Acidic solution ,electrolyte Small ,cathodic area Large anodic area
27.
28. Absorption of oxygen Sept. /06 MA/chem/RCET Aqueous neutral solution rust Large cathodic area Small anodic area
29.
30.
31.
32.
33.
34.
35. Galvanic / Bimetallic Sept. /06 MA/chem/RCET Zn Cu Electronic current Cathode ,protected Anode , attacked electrolyte
36.
37.
38.
39.
40. Concentration cell corrosion Sept. /06 MA/chem/RCET Water line corrosion Zn rod Corroding anode NaCl solution More oxygenated part Less oxygenated part
![[object Object],Sept. /06 MA/chem/RCET](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)