Laboratory Testing to Identify Permanent PVD Coatings to Minimize Lubricant Use During Forging

Transcription

1 Laboratory Testing to Identify Permanent PVD Coatings to Minimize Lubricant Use During Forging T. Kehe, S. Midson, A. Korenyi-Both, K.D. Clarke Forging Technical Conference, Sept. 11, 2018, Long Beach, CA. 1

2 Project Goals Utilize permanent PVD thin-film coatings Apply to forging dies Minimize friction coefficient Reduce use of lubricants Reduce lubricant overspray Improve die life Improve cycle times Improve quality of forgings 2

3 Project Approach Leverage the recent CSM Lube Free die casting die coating project New PVD coatings reduced lubricant use significantly Apply similar coating technologies to forging dies Develop a flexible testing methodology Evaluate relative friction coefficients of PVD surface coatings during aluminum forging (die temperatures <400 C) 3

4 Project Tasks 1. Perform literature review of coatings used in forging and metals fabrication 2. Design and fabricate tooling for laboratory forging test 3. Set up laboratory testing procedure and procure coated die test samples 4. Perform plant trial of best PVD coating identified during laboratory testing 5. Reporting 4

5 Today Literature review of PVD coatings Die design and fabrication Validation of friction testing procedures and initial friction test results PVD coating test matrix 5

6 Literature review of PVD coatings 6

7 Literature review of PVD coatings Coating thickness is typically <10 m Thicker coatings will spall Substrate temperature needs to be less than 550 C (1,000 F) during application To avoid over-tempering of hardened tool-steel substrate PVD coating meets these criteria

8 Literature review of PVD coatings PVD coatings are not common on forging dies More common on die casting dies Most studies focused on wear resistance and die life Not on improving lubricity Coatings examined include: CrN, TiN, TiC, TiCN, TiAlCN, AlCrN, TiAlN Data from Leskovsek et al. showed that TiCN did reduce coefficient of friction H11 plasma nitrided, PECVD Source: Leskovsek et al., Wear, 2009

9 Literature review of PVD coatings Several hard coatings have the potential for improving lubricity Diamond like carbon (DLC) CrN/SiC TiCN Coating Coefficient of Friction CrN 0.28 CrN/DLC 0.07 CrN/SiC 0.07 Cutting applications Sources: Mulligan et al., Mat. & Man. Proc., 2014 Donnet and Erdemir, 2008

10 Literature review of PVD coatings MoS 2 is an excellent lubricant Due to its layered structure MoS 2 can be directly deposited Deposited structures are very soft Easily detach from substrate MoS 2 has been deposited as part of a harder coating Titanium AlCrN Coefficient of friction values were reduced Cold-forging (a) Uncoated substrate (M2) (b), (c) & (d) utilizing (Cr 1-X Al X )N/ Mo Y S Z -type coatings Source: Bobzin et al., Ad. Eng. Mat., 2016

11 Literature review of PVD coatings For applications at high temperatures Unreasonable to expect materials to resist oxidation for long periods Utilize oxide materials with low interfacial shear strengths Layered structure of V 2 O 5 V atoms as grey balls O atoms as red balls V 2 O 5 MoO 3 Source: Mulligan et al., Surf. & Coat. Tech., 2010

12 PVD coatings Type of Coating Specifics Supplier Temperature Single-layer hard Tribologix, Dayton, TiCN coatings Ionbond <400 C Super MoS 2 Tribologix 375 C Ti-MoS 2 (MOST) Teer in UK, Ionbond <350 C AlCrN-MoS 2 Tribologix Multi-layer hard TiCN-TiMoS coatings 2 Teer CrN-DLC Phygen <300 C CrN-SiC Phygen i-kote Tribologix 350 C Noble Metals Hard coating plus noble metal Voevodin, Scharf & Samir at UNT Highly lubricious oxide -- None identified Plasma Sprayed PS400 NASA Laser Textured Laser texture a TiCN coating Tribologix/CSM <500 C

13 Test methodologies and die design 13

14 Test methodologies and die design

15 Test methodologies and die design

16 Test methodologies and die design Easy installation and removal Trials of multiple coatings Ability to quickly switch die faces Room temperature to ~500 C capability Fit on available 100 kip hydraulic press Measure load and displacement

17 Test methodologies and die design Design tooling with removable inserts In-house surface preparation of uncoated die sets Coat smaller pieces Send sets of tooling to various vendors for coating Allow for elevated temperature testing Easily replaceable Effective stress, ksi Aluminum ring 1 OD, ½ ID 0.2 in/s compression velocity Applied to a 100 kip force

18 Test methodologies and die design 25 mm

19 Test methodologies and die design

20 Validation of friction testing procedures and initial friction test results 20

21 Friction testing results: 6061 RT No lubricant Dry graphite spray MoS 2 grease Left to right: Increasing reductions in height Top to bottom: Increasingly effective lubricants

22 Friction coefficient Friction testing results Die inserts ground to 1200 grit and polished from 6μm to 3μm to 1μm Friction coefficient responds to multiple tests Surface conditioning performed on dies No lubricant, room temperature Test number

23 Decrease in inside diameter Friction testing results lubricant amount No Lubricant CRC Graphite Molykote MoS % height reduction Friction factor

24 Decrease in inside diameter Friction testing results No lube, 200 C No Lubricant CRC Graphite Molykote MoS % height reduction Friction factor

25 PVD Coating Test Matrix 25

26 PVD coating test matrix 6 die sets (uppers + lowers) 1 H13 set used for no-coating baseline 4 H13 sets are at vendors for coating Can be re-coated Surface imaging, tribology, and metallographic examination of coating performance also possible 1 W303 set will be used to validate nocoating baseline values and coating effectiveness on a different substrate

27 PVD coating test matrix Type of Coating Specifics Supplier Temperature Single-layer hard Tribologix, Dayton, TiCN coatings Ionbond <400 C Super MoS 2 Tribologix 375 C Ti-MoS 2 (MOST) Teer in UK, Ionbond <350 C AlCrN-MoS 2 Tribologix Multi-layer hard TiCN-TiMoS coatings 2 Teer CrN-DLC Phygen <300 C CrN-SiC Phygen i-kote Tribologix 350 C Noble Metals Hard coating plus noble metal Voevodin, Scharf & Samir at UNT Highly lubricious oxide -- None identified Plasma Sprayed PS400 NASA Laser Textured Laser texture a TiCN coating Tribologix/CSM <500 C

28 PVD coating test matrix Friction testing on uncoated dies and four initial PVD coatings selected (5) Temperature will be varied from RT to 300 C (4) Tests will be performed with and without lubricant MoS 2 and Graphite (3) Three sets of rings at three deformation levels (9)

29 Summary Flexible forging tooling has been designed and built Room temperature to 500 C Loads up to 100 kip 6 sets of interchangeable die inserts Ring-compression friction tests have been validated Polished as-heat treated (uncoated) dies Room temperature to 300 C Forging die coatings Literature review complete List of promising coatings compiled Four initial coatings selected for application to dies (underway)

30 Acknowledgements FIERF stage gated grant, Laboratory Testing to Identify Permanent PVD Coatings to Minimize Lubricants Use During Forging FIERF board stage gate reviews and guidance NSF REU program grant through the Center for Advanced Non-Ferrous Structural Alloys CSM undergraduate research support Die materials Bohler-Uddeholm (Patricia Miller), H13 and W303 inserts Hitachi (Tom Bell), H13 inserts Finkl (Al Underys), 4340 die blocks

31 Test methodologies and die design Trevor Kehe Currently a senior at CSM Pursuing a degree in metallurgical and materials engineering Started on Forging Coatings project in August, 2017 Designed die sets Oversaw manufacturing/machining Initiated testing program Interested in pursuing a graduate degree at CSM Interests Mines Baseball 2017: 1 out away from CWS 2018: 2 nd in RMAC

32 Thank you!

33 Literature review of PVD coatings Mechanism Material Examples Temp. Range Traditional liquid lubricants Oils and greases <~250 C Atomic structures that can easily shear PVD hard coatings (can contain softer lubricating phases) Soft metals within hard coatings that diffuse to contact surfaces MoS 2, graphite Diamond like carbon, TiCN, CrN/SiC, i-kote Ag, Au, Cu encapsulated in TiN, CrN, VN, YSZ, CrAlN <300 C < C depending upon coating C Lubricious oxides V 2 O 5, MoO C Source: Adapted from Voevodin et al., Surf. & Coat. Tech., 2014

34 Friction testing results: 6061 RT Lubricant application conditions did not affect room temperature friction factor

35 Friction testing results: 6061 RT Left to right: Increasing reductions in height No lubricant

36 Literature review of PVD coatings PS400 Nickel-molybdenum binder for strength Silver and barium calcium fluoride are added for lubrication Layered microstructure Source: DellaCorte & Edmonds, NASA Report, 2009

37 Literature review of PVD coatings Ag-Ta-O Sputtered from Ta and Ag targets in reactive oxygen atmosphere Exhibit extremely low coefficient of friction at C Source: Stone et al., Surf. & Coat. Tech., 2013 CoF for four silver tantalate coatings

38 Friction testing results Identification of lubricants to be used for further tests (Graphite, MoS 2 ) Four trials run at three different deformation amounts for each condition At max load, a greater % deformation is achieved with lubrication

39 Literature review of PVD coatings Noble metals are dispersed in hard coatings Ag in CrN Ag in CrAlN Ag in TiC Noble metal diffuses to surface Provide lubricity at temperature greater than 300 o C Source: Voevodin et al., Surf. & Coat. Tech., 2014

40 Temp ( C) Test methodologies and die design Cooling of dies during test set up recorded Heat higher than target test temperature Test is run when goal temperature is reached Al samples reach same temperature as dies quickly C 230 C 300 C Time (sec)

41 Literature review of PVD coatings Traditional Surface Treatments Hard Thin-Film Coatings Weld Overlay