© 2012 su-jin kim gnu surface & metrology manufacturing processes 4. surface & metrology

© 20© 201212 Su-Jin Kim GNUSu-Jin Kim GNU

Surface & MetrologySurface & MetrologyManufacturing ProcessesManufacturing Processes

Manufacturing Processes Manufacturing Processes

44.. Surface & Metrology Surface & Metrology



Index

• Surface roughness• Friction, wear• Surface treatment & Coating• Metrology



Surface Structure ( 표면 구조 )

• Contaminant ( 불순물 )• Oxide ( 산화물 ) Fe2O3, Al2O3, Cu2O, CrO• Surface structure( 표면구조 ): work-hardened layer(

가공경화층 ), residual stress( 잔류응력 ) • Metal substrate( 모재 )

1-100 nm Contaminant

10-100 nm Oxide

1-100 μm Surface structure

Metal substratestress



Stylus

Surface Roughness ( 표면 거칠기 )• Arithmetic average ( 산술평균 ) Center line average ( 중심선평균 )

• Root-mean-square average ( 제곱평균 )

• Maximum roughness height ( 최대높이 ) Rt

n

iia y

nR

1

1

n

iiq y

nR

1

21

yy1 y2 …

…yn

Surface profile data

Center line



Friction ( 마찰 )

• Friction is defined as the resistance to relative sliding between two contact bodies under load.

• Adhesion( 융착 ) theory of friction: Two clean surfaces contact at only small area.

Real area of contact, Ar

N

F

Normal force, N

Fric

tion

forc

e, F Ar<<A Ar<A Ar~A

Sliding

Bending

Sheet forming

Forging

Drawing

Metal cutting



Wear( 마멸 )

• Adhesive ( 융착 )• Abrasive ( 연삭 ) • Corrosive ( 부식 )• Fatigue ( 피로 )



Lubricant ( 윤활 )

• Oil

• Zinc phosphate( 인산아연 ) conversion coating(전환피복 ) for carbon steel: Chemical reaction with acid generates rough surface that contains lubricant reducing friction at forging and drawing. Oxalate(수산염 ) conversion coating for stainless steel.

http://www.youtube.com/watch?v=u5RA3zHLIdM How lubricant



Surface treatment ( 표면처리 )

• Shot peening

• Roller burnishing

Impact with high speed metal ball

Compressive residual stress

Roller

Compressive residual stress

http://www.youtube.com/watch?v=B6YxFxMCKkQ Burnishing



Surface Coating ( 표면코팅 )

• Physical vapor deposition(PVD, 물리증착 ): deposit vaporized material onto workpiece surface in vacuum and at high temperature.

http://www.youtube.com/watch?v=Ukvs6Rct4w8 PVD Lab.http://ma.gnu.ac.kr/vod/surface/pvd_coating.wmv PVD Tools



Surface Coating

• Electroplating( 전기도금 ): Metal ions(+) in a solution are moved by an electric field to coat an cathode(-) electrode.

Zn++

SiO4--

Zn++

SiO4--

H+

(-)(+)

Zn

http://www.youtube.com/watch?v=z7f7dQF2KLA Electroplating



Surface Coating

• Anodizing( 양극처리 ): an electrolytic oxidation process used to increase the thickness of the natural oxide layer on the surface of metal parts connected to anode(+).

• Aluminum alloy are anodized to increase corrosion resistance, surface hardness, and to allow coloring.

O2-

(-) (+)

O2-

Al

Air bubble

http://www.youtube.com/watch?v=3ZhVOy-ytJY Anodizing



Surface Coating

• Phosphate conversion coating ( 인산염 피막 ) are used on steel parts for corrosion resistance, lubricity, painting foundation. Phosphoric acid( 인산 ) chemically react with the surface of the part being coated to form a layer of insoluble, crystalline phosphates.

• Manganese phosphates( 인산망간 ) are used both for corrosion resistance and lubricity. Iron phosphates(인산철 ) are typically used as a base for further coatings or painting. Zinc phosphates( 인산아연 ) are used for rust proofing (P&O), a lubricant base layer, and as a paint/coating base.

© 2012 su-jin kim gnu surface & metrology manufacturing processes 4. surface & metrology

Documents

surface metrology slide

cro surface structure

n friction force

adhesion theory of friction

r n f normal force

nm oxide

nm contaminant

contact bodies