Effects of Wire-Electro Discharge Machining Process on Surface Integrity of WC-10Co Alloy Nilüfer Orhon*, Erdem Şireli nilufer.orhon@bohler.com.tr, erdem.sireli@bohler.com.tr 2nd Surface Treatment Symposium June 25-27, 2014, Istanbul-Turkey

Outline Cemented Carbides Forming Methods Wire-Electro Discharge Machining (W-EDM) Pros and cons of W-EDM Chemical Vapor Deposition Experimental Surface Characterization Mechanical Tests Conclusions 25.06.2014

Cemented Carbides WC-Co Other Carbides; TiC, TaC, NbC, VC, Cr3C2 HARDNESS & TOUGHNESS WC Co Co Other Carbides WC WC-Co Other Carbides; TiC, TaC, NbC, VC, Cr3C2 HEAT RESISTANCE Wear ResistanCE 25.06.2014

Conventional Forming Methods GRINDING Low removal rate* High Costs* Waste Management TURNING MILLING Talaş kaldırma temeline dayanan yöntemler * M.P. Jahan et al. / International Journal of Machine Tools & Manufacture 51 (2011) 837–858 25.06.2014

W-EDM Process W-EDM is a non-traditional manufacturing process based on removing material from a part by means of a series of repeated electrical discharges between a tool (wire) and the part being machined in the presence of a dielectric fluid. Temas yok. Dielektrik; arkı kanalize, kopan parçaları uzaklaştır, soğuma sağlar. CuZn Transferinden bahset. 25.06.2014

Irrespective of Mech. Prop. Pros and cons of W-EDM Pros Cons Complex Shapes Conductivity Cost Effective Surface Integrity Irrespective of Mech. Prop. Decarburization Cracks* Re-cast Layer DISADVANTAGES Corrosion* ETA-PHASE Decarburisation Voids *K. Bonny et al./Tribology International 43(2010)40–54 43 25.06.2014

W-EDM Surfaces Roughness Number of Cuts Lower Discharge Current Rough Cut (1 Cut) Lower Discharge Current Lower Discharge Power Higher Wire Speed Roughness Medium Cut (2~4 Cut) Finish Cut (>5 Cut) Number of Cuts 25.06.2014

Improving W-EDM surface integrity Finish Cut Blasting PVD Coating* * B. Casas et al. / Thin Solid Films 447 –448 (2004) 258–263 25.06.2014

Chemical Vapor Deposition Chemical reactions of gaseous reactants on heated substrates through exact pressure and temperatures Non-line of sight method High temperature process (850-1020°C) Various materials can be deposited; Semiconductors Metallic Films Refractory Ceramic Materials Coating Temperatures; 900°C 1015°C Working Temperatures: 900°C,1015°C 25.06.2014

The aim of the study Effects of EDM caused damaged zone on surface integrity of WC-10Co alloy Effects of dry blasting process on EDM’ed surfaces Morphology of TiN coatings applied on as EDM’ed and as EDM’ed+dry blasted surfaces Mechanical properties such as adhesion and wear of TiN coatings deposited on different surface conditions (as EDM’ed/as EDM’ed+dry blasted) 25.06.2014

Experimental Plan Application of W-EDM process with different number of cuts Surface roughness measurements and SEM observation before dry blasting Dry Blasting application Surface roughness measurements and SEM observation after dry blasting TiN coating through MT-CVD technique Phase analysis with thin film X ray diffraction (XRD) Surface roughness measurements after TiN coating application Morphological analysis of the coatings via Scanning Electron Microscopy (SEM) Adhesion tests (HRC) Wear tests (ball on disk) 25.06.2014

Surface Roughness - Before Dry Blasting 2060 nm EDM (1 Cut) 518 nm EDM (4 Cuts) 211 nm EDM (5 Cuts) 142 nm EDM (7 Cuts) 203 nm Ground 25.06.2014

SEM Images – Before Dry Blasting EDM (1 Cut) EDM (4 Cuts) EDM (5 Cuts) EDM (7 Cuts) Top EDM (1 Cut) EDM (4 Cust) EDM (5 Cuts) EDM (7 Cuts) Cross Section 25.06.2014

Surface Roughness - After Dry Blasting 858 nm *DB (1 Cut) 303 nm DB (4 Cuts) 287 nm DB (5 Cuts) 282 nm DB (7 Cuts) *DB: Dry Blasted Dry blasting parameters: 10 seconds 5 bar pressure 320 mesh Al2O3-SiC mix powder 25.06.2014

Surface Roughness - After Coating 1710 nm EDM (1 Cut)+TiN 493 nm EDM (4 Cuts)+TiN 225 nm EDM (5 Cuts)+TiN 177 nm EDM (7 Cuts)+TiN 936 nm DB (1 Cut)+ TiN 342 nm DB (4 Cuts)+TiN 273 nm DB (5 Cuts)+TiN 221 nm DB (7 Cuts)+TiN 159 nm Ground+TiN 25.06.2014

XRD Patterns Co6W6C WC CuZn WC – Etafaz - CuZn 25.06.2014 Ground + TiN EDM (1 Cut) + TiN DB (4 Cuts) + TiN DB (1 Cut) + TiN EDM (4 Cuts) + TiN Co6W6C WC WC – Etafaz - CuZn CuZn 25.06.2014

Surface Morphology of the Coatings @ 900°C EDM (1 Cut) + TiN EDM (4 Cuts)+TiN EDM (5 Cuts) + TiN Blasted morphology -> Nodular + Star + Lenticular Ground + TiN *H.-E. Cheng, Y.-W. Wen / Surface and Coatings Technology 179 (2004) 103–109 DB (1 Cut) + TiN DB (4 Cut) + TiN DB (5 Cut) + TiN 25.06.2014

Cross-sectional SEM Images of the Coatings @ 900°C EDM (1 Cut) + TiN - SEI EDM (1 Cut) + TiN - BSI DB (1 Cut) + TiN Ground + TiN 25.06.2014

Surface Morphology of the Coatings @ 1015°C EDM (1 Cut) + TiN EDM (4 Cut) + TiN EDM (5 Cut) + TiN Ground + TiN DB (1 Cut) + TiN DB (4 Cut) + TiN DB (5 Cut) + TiN (1) (2) J. Wagner et al. / International Journal of Refractory Metals & Hard Materials 26 (2008) 120–126 H.-E. Cheng, Y.-W. Wen / Surface and Coatings Technology 179 (2004) 103–109 25.06.2014

Hardness Rockwell-C adhesion test Adhesion Tests @ 900°C EDM (1 Cut) + TiN DB (1 Cut) + TiN Standard VDI 3198 Hardness Rockwell-C adhesion test Ground + TiN EDM (4 Cuts) + TiN DB (4 Cuts) + TiN 25.06.2014

Ball on Disc Test Apparatus Wear Tests Ball on Disc Test Apparatus WEAR TEST PARAMETERS Load 10 N Distance 150 m Wear Track Radius 2.5 mm Linear Speed 10 cm/s Ball Alumina Ball Diameter 5 mm LOAD ALUMINA BALL 25.06.2014

Wear Tests As EDM’ed (1 cut) and coated tribolayer μmean = 0.72 25.06.2014

Wear Tests As EDM’ed (1 cut) and coated – Ball wear scar 25.06.2014

Wear Tests As dry blasted (1 cut) and coated μmean = 0.66 X 25.06.2014

Wear Tests As dry blasted (1 cut) and coated – Ball wear scar 25.06.2014

Hill/valley structure due to direct impingement in dry blasting Wear Tests As dry blasted (1 cut) and coated - Material transfer from alumina ball 858 nm Hill/valley structure due to direct impingement in dry blasting Higher deformation resistance of mixed (nodular, star shaped and lenticular) morphology * Substrate Undeformed TiN Al rich tribolayer Polished TiN * H.-E. Cheng, Y.-W. Wen / Surface and Coatings Technology 179 (2004) 103–109 Wear track 25.06.2014

The Results of Wear Tests As EDM’ed (1 cut) As dry blasted (1 cut) 25.06.2014

Conclusions Better surface integrity through dry blasting after w-EDM process TiN morphology changes from coarse nodular (as EDM’ed) to the mixed structures of fine nodular/star shaped/lenticular (as dry blasted) crystals at 900 °C, depending on the surface condition The adhesion strength of TiN layer was improved by applying dry blasting on EDM’ed surfaces The friction and wear properties of TiN coating are relatively better on dry blasted samples 25.06.2014

Dr. Güldem KARTAL ŞİRELİ Acknowledgements Prof. Dr. Mustafa ÜRGEN Doç. Dr. Kürşat KAZMANLI Dr. Güldem KARTAL ŞİRELİ 25.06.2014

THANK YOU 25.06.2014