Chap.31 Surface Treatment, Finishing & Surface Integrity

1. Chap.31 Surface Treatment, Finishing & Surface Integrity

2. Tab3-1 Contents • Mechanical Cleaning & Finishing: • Abrasive Cleaning, Barrel Finishing & Tumbling, Vibratory Finishing, Mass-Finishing, Belt Sanding, Wire Brushing, Buffing, Electorpolishing • Chemical Cleaning: • Alkaline Cleaning, Solvent Cleaning, Vapor Degreasing, Ultrasonic Cleaning, • Acid Pickling • Coatings: • Painting( Wet / Dry), temperature), Hot Dip Coating, Chemical Conversion Coating, Coloring Metals, Electroplating, Anodizing, Electroless Plating, Mechanical Plating, Porcelain Enameling • Vaporized Metal Coatings, Cladding, Textured Surface, Coil-coated Sheet, Edge Finishing & Burrs, Fatigue Failures

4. Tab31-1

6. Tab3-1 Mechanical Cleaning & Finishing • Abrasive cleaning: Some type of abrasive, usually sand and steel grit, or a high-velocity air blast is impelled against the surface to remove foreign materials such as sand or scales. • Barrel finishing or tumbling: Barreling or vibrating with the use of synthetically shaped media and compounds • Buffing: Polishing with a revolving cloth buffing wheel • Wire brushing • Belt sanding • Electropolishing (anode: work): 전기도금(anode: plate metal; cathode: work)의 원리를 반대로 이용

7. Mechanical Cleaning and Finishing

8. Mechanical Cleaning and Finishing

9. Mechanical Cleaning and Finishing

10. Tab31-2 Mass Finishing

11. Mechanical Cleaning and Finishing

12. Tab3-1 Chemical Cleaning • Alkaline cleaning: emulsification (유화) of the oils and greases • Solvent cleaning • Vapor degreasing • Pickling • Ultrasonic cleaning • Painting • Acrylic enamels are widely used for automobile finishes. • Dipping, hand spraying, automatic spraying, electrostatic spray finishing, and electrocoating • Often at least two coats of paint are required. • The first coat is to 1) assure adhesion, 2) provide a leveling effect, and 3) improve corrosion resistance and thus prevent later coatings from being dislodged.

13. Tab31-3 Coatings

14. Tab3-1 Metal/Oxide Coatings and Platings • Hot dipping (용융도금법): 주로 주철이나 강을 도금재료의 용탕 속에 담갔다가 꺼냄으로써 피막을 입혀 내부식성을 높히는 것. 예: Galvanized plate (아연도강판): 자동차 차체용 • Electroplating (전기도금법): 음극(cathode)의 소재와 양극(anode)의 도금재료 사이의 전위차에 의해 야기되는 전해작용을 이용, 양극에서 방출되는 금속이온들이 전해액 속의 이온들과 결합하여 음극으로 이동되어 증착. 도금재료: 크롬, 니켈, 카드뮴, 구리, 아연, 주석. • Electropolishing (anode: work): 전기도금(anode: plate metal; cathode: work)의 원리를 반대로 이용 • Anodizing (양극처리법): 소재를 양극으로 하면 양극에서 발생하는 산소를 이용하여 소재표면에 산화층을 입힐 수 있음, 주로 알루미늄, 착색피막, 도색 예비공정(알루미늄은 도색이 곤란), 내부식성 증가 • Electroless plating (무전해도금법): 화학반응을 이용한 도금, 도금재료: 주로 니켈, 전기 전도성이 없는 플라스틱도 도금 가능.

15. Coatings

16. Tab31-4 Coatings

17. Coatings

18. Coatings

19. Coatings

20. Coatings: Anodizing

21. Coatings: Electroless Plating

22. Tab3-1 Vaporized Metal Coatings • Vacuum coating (진공증착법) • 고온의 진공상태에서 피복될 금속을 기화시켜 모재의 표면에 매우 얇은 피복층을 형성 • 복잡한 형상에도 균일한 피복 가능 • 고가 금속(금, 은)을 증착, 장식용(보석, 가전제품) • Sputtering • 불활성기체(아르곤)가 전기장에 의해 이온화되면서 생기는 양이온이 피복재료(음극)를 때리면 피복재료의 원자가 튀어 나와 모재표면에 응축됨. • 면도날의 크롬 피복: 내부식성 향상

23. Edge Finishing and Burrs

24. Tab31-5

25. Edge Finishing and Burrs

26. Surface Integrity

27. Tab31-6 Surface Integrity

28. Surface Integrity

29. Surface Integrity

30. Fatigue Failure Associated with Surface Integrity

31. Fatigue Failure Associated with Surface Integrity