Friction and Wear Enhancement ofTitanium Alloy Engine ComponentsPeter J. Blau, PhD, Principal InvestigatorMaterials Science and Technology DivisionOak Ridge National LaboratoryORAL PRESENTATION: May 12, 2011Project ID: pm007 BlauThis poster does not contain any proprietary, confidential, or otherwise restricted information1Managed by UT-Battellefor the U.S. Department of Energy

OverviewBarriersTimeline Project start date: October 2009 Project end date: September 2011 Percent complete: 67%BudgetTotal project funding: Funding for FY10: Funding for FY11: Funding for FY12:DOE 100% 274 K 150 K(pending)Barriers addressed: Light-weighting components toimprove heavy truck engine thermalefficiency to 50% by 2015. High Efficiency Clean Combustion(HFCC) increases strength reqm’ts Ti alloys 43% lighter than steel buthave friction and wear challenges.Partners 2Managed by UT-Battellefor the U.S. Department of EnergyNDA with Cummins Engine Co.Informal collaborations: surfacetreatment/coatings developersProject lead: ORNL

Relevance to OVT Goals Addresses the goal of 50% improvement in freight efficiency (ton-miles/gallon) bysubstituting strong, durable, corrosion-resistant alloys for steel components. Enable increased use of titanium alloys in friction- and wear-critical enginecomponents likeConnecting rods (end brgs)Pistons (wrist pin and skirt area)Valves and valve guidesCrankshaftsMovable vanes in turbochargersBushings in EGR systems Compared to other light metals, like Al and Mg, Ti alloys offer outstanding corrosionresistance, high specific strength and stiffness, and decades of aerospacetechnology to leverage their development. Development of lower-cost Ti raw materials (e.g. powders) in recent years expandsthe possibilities to use Ti for engine components.3Managed by UT-Battellefor the U.S. Department of Energy

ObjectivesFY 2011 Objectives: Complete Friction and Wear Studies of Coatings and Treatments that passedScreening Tests in FY 2010: Conduct in-depth investigation of commercial andexperimental surface engineering treatments that passed pre-screening tests in FY2010.* Understand why treatments and coatings performed as they did as a basisfor further optimization. Complete Construction of a Variable-Load Bearing Test (VLBT) Rig andInvestigate Down-Selected Coatings and Surface Treatments: Engine bearingsexperience variable, non-steady-state loadings which can cause intermittent wearand periodic loss of lubricating films. Based on a tribosystem analysis for connectingrods and advice from an OEM, the programmable VLBT system will be used to findthe best surface engineering treatments for Ti alloys. Identify a Commercial Diesel Engine Connecting Rod as a candidate forreplacement with surface engineered Ti –based version.* presented at the International Conference on Wear of Materials, Philadelphia PA (April 3-7, 2011).4Managed by UT-Battellefor the U.S. Department of Energy

Milestones for FY 2011Month / YearMilestoneMarch / 2011Complete construction, instrumentation, and baseline tests of avariable-load large-end bearing testing system (VLBT): Completemachining and assembly, installation of sensors and computerizedload controls. Verify operating performance. Conduct baseline testson non-treated Ti alloy and bearing bronze against a hardened steelcounterface (surrogate for the crankshaft material),Complete VLBT tests of down-selected surface engineeringtreatments and coatings for Ti: Compare VLBT baseline lubricatedfriction and wear test results with those for promising surfacetreatments and coatings that passed Phase 1 screening in FY 2010.Sep / 20115Managed by UT-Battellefor the U.S. Department of Energy

Bearing surfaces in a connecting rodSmall end bearing – piston end (oscillating,high load, low speed)Criteria for plain bearings:Maximum load carrying capacity,maximum permissible wear, maximumoperating temperature, effect oflubricant loss (‘starvation’)Current insert materials are relativelysoft and some contain Pb:Al-Sn, Al-Sn-Cu, Al-Sn-Ni-Cu, Sn-Al,Al-Si, Cu-based, and multi-layeredBig end bearing – crank shaft end(rotating, high load, medium, speed)6Managed by UT-Battellefor the U.S. Department of Energy

Large-end ‘tri-metal’ bearing inserts in atypical HDD engine connecting rodISX15Solid lubricant layerBronze alloy layer(Pb, Sn, In)Polished Cross-SectionSteel back plateIndentation testing reveals insert layer functionalityBack plate providesstiffness and strengthBronze layer impartsembedability and solidlubrication during start-upand boundary lubricationSoft upper layer providesconformability andlubrication during wear-in7Managed by UT-Battellefor the U.S. Department of Energy

Why Ti? Lightweight and corrosion-resistant Metallurgy well-studied (aerospace) New, more cost-effectibe processingtechnologies being developed 43% lower weight for the same sized part8PropertyCarbon steelAl alloys (typ.)Mg alloys (typ.)Ti-6Al-4V (typ.)Density (g/cm3) modulus(GPa) strength*45. – 60.35. – 125.130.200 - 250.CorrosionPitting, generalcorrosion, scalingproblemsGalvanic corrosion,attack by road saltsExcellent resist. toroad salts, aqu.corrosionThermal cond.(W/m-K)42.- by UT-Battellefor the U.S. Department of EnergyStress corrosion,exfoliation, pitting 160.* Specific strength Ultimate tensile strength/density

Year 1Approach(Phases I and II Tasks)Investigate current state of theart in Ti surface engineering,including aerospace solutionsAnalyze force, speeds, andoperating environments of endbearings on connecting rodsIdentify candidate surfaceengineering methods, preparesimple lab test couponsDesign and build a spectrumloaded, rotary bearing test systemTest and down-select promisingsurface engineering approachesConduct baseline tests on currentCR bearing materialsPhase IPhase II9Managed by UT-Battellefor the U.S. Department of Energy

Identify most promising surfaceengineering methodsConduct spectrum-loaded frictionand wear tests on leadingcandidates / compare to currentbearing materials (inserts)Identify full-scale testingfacilities and dimensions for aprototype conn rodPrepare one or more prototype Ticonn rods with engineeredsurfacesDynamometer tests at an enginetest facility (tbd)Phase IIPhase III10Managed by UT-Battellefor the U.S. Department of EnergyYear 3Year 2Continue coupon testing onleading candidates from Phase Iand VALIDATION(Phases II and III Tasks)SCALE-UPApproach

21 Materials, Treatments and Coatings Were Consideredand Evaluated in FY 2010 using Bench-Scale TestsBULK MATERIALSBronze referenceNovel NASA alloy123Baseline, non-treated Ti-6Al-4VPb-Sn bronze alloy CDA 932 (baseline bearing bronze)*60Ni-40Ti (a NASA development)**MECHANICAL TREATMENTS45Shot peening*Low plasticity burnishing*THERMAL and CHEMICAL TREATMENTSORNL developed ODTreated NASA alloy678910Oxygen diffusion treatment (developed by J. Qu at ORNL)**Carburizing*Nitriding*Surface alloying to form 60Ni-Ti (pending results of tests on bulk 60Ni-40Ti,line 3)Electrochemical anodizing*HARD and SOFT COATINGSCommercial coatingsANL diamond filmNanocoating (from aDOE/ITP project)IR Ti composite fromORNL/LDRD11Managed by UT-Battellefor the U.S. Department of Energy11121314151617Both commercial andexperimental treatments werepre-screened in Phase ITiN hard coating*CrN hard coating*DLC hard coating ***Nanocomposite AlMgB (developed under a DOE/ITP project)****In situ IR-produced Ti MMC (developed at ORNL under Laboratory DirectedR&D funding)**Metallic soft coating of Cu-Ni-In on Ti-6Al-4V*Metallic soft coating of Cu-Ni-In on CDA 932 bronze*HYBRID TREATMENTS18192021Shot peening* after oxygen diffusion treatment**Shot peening* after carburizing*Shot peening* after nitriding*Cu-Ni-In soft coating* after shot peening** Commercial source,*** Produced at ANL** Produced at ORNL**** Produced at a company R&D Lab

Technical Progress: Phase I Screening (FY2010)ASTM Standard G133 (reciprocating pin-on-flat standard developed by ORNL underDOE/OVT sponsorship)Procedure A: Load 25 N, 10 mm stroke, 5 cycles/s, 100 m sliding distance, nolubricant, room temperatureModified Procedure B: Load 200 N, 10 mm stroke, 10 cycle/s, 400 m sliding distance,lubricated,* room temperatureNormal Force(Load)* Lubricant: 15W40 engine drain oil, Mack T-11 standard test, 252 hrs, from Southwest ResearchInstitute, San Antonio, TX12Managed by UT-Battellefor the U.S. Department of Energy

Technical Progress Phase I: 8 of 19 ‘passed’Tests in diesel engine drainoil – AISI 52100 bearingsteel as the slidersFailure criteria: CoF 0.15, unstablesliding, excessive noise or vibrationduring testing causing premature testtermination.13Managed by UT-Battellefor the U.S. Department of Energy

Technical Progress: Wear Test Results*Wear of both the (Ti) flat specimens and the opposing bearing steel sliders wasmeasured to assess the total tribosystem wearTi-6Al-4V(non-treated)Wear scar volume was measuredby vertical scanning interferometry(HTML, Tribology Research User Center)The flat specimen usually wore morethan the slider, but not always.* D. Bansal, O. L. Eryilmaz, and P. J. Blau, pres. at the International Conference on Wear of Materials(Philadelphia, April 2011), and published in Wear journal (in press, 2011).14Managed by UT-Battellefor the U.S. Department of Energy

Due to engine dynamics, connecting rodbearings operate under varying loads Causes: inertia of therotating shaft, periodiccombustion events, enginedynamics Effects: Varying normalforce, changing oil filmthickness, and changinglubrication regime withineach rotation cycle.A variable-load bearing testingsystem can provide a morerealistic simulation of thestresses on large-end bearingsduring use.15Managed by UT-Battellefor the U.S. Department of EnergyForces on a big end bearing(replotted from a polar loaddiagram)

A Variable Load Bearing Test System (VLBT) wasDesigned and Built at ORNL Torque, speed, normal and tangential (friction) force measurement Spectrum loading capabilities to provide for ranges of lubricant behavior (mixed regime,boundary lubrication, dry or starved, etc.) Fixtures were designed to accommodate both simple specimens and sections cut from actualconnecting rod bearingsNormal force actuatorNormal force load cellLoading arm pivotCylindrical specimen chuckTorque cellVariable speed motorBearing specimen(loads from below)16Managed by UT-Battellefor the U.S. Department of Energy

Technical Accomplishments and Progress* Conducted baseline friction and wear tests. Selected test method (ASTMG133 – Procedures A and B), and conducted reciprocating pin-on-flat tests on 21materials, coatings, and surface treatments to down-select materials for Phase II.Published and presented results. Designed, variable-load bearing test system (VLBT). Procured commercialparts and computer, machined fixtures, installed sensors and loading system,programmed computer for control and force measurement, conductedcalibrations and baseline tests on bronze and non-treated Ti-6Al-4V. Signed NDA with Cummins to share information on lightweight connecting rodrequirements. Conducted additional, studies of the leading surface engineeringtreatments to evaluate repeatability of performance. Based on initial results,are re-running some G133 experiments while also preparing optimizedspecimens for VLBT testing.17Managed by UT-Battellefor the U.S. Department of Energy

Collaboration and Coordination withOther Institutions / DOE Projects18 Cummins Engine Company (Columbus, IN) – discussions and advice onapplications for Ti in diesel engine components, NASA, Glenn Research Center (Cleveland, OH) – Exploring a novel Tibased intermetallic alloy for a possible surface alloying approach. Argonne National Laboratory (Argonne, IL) – Provided DLC films on Ti andis a co-authoring the Wear of Materials Conference paper (2011) Eaton Corporation/Ames Lab (Southfield, MI) DOE/ITP Project onNanocomposite AlMgB/TiB2 composites. Commercial suppliers: Phygen Coatings (Minneapolis, MN), Tiodize(Huntington Beach, CA), Solar Atmospheres (Souderton, PA), and MetalImprovement Company (Paramus, NJ) ORNL – Two LDRD funded projects on (a) IR-treated Ti to resist galling, and(b) Ti composite armor using P/M processing methodsManaged by UT-Battellefor the U.S. Department of Energy

Proposed Future WorkRemainder of FY 2010: Continue bench-scale friction and wear tests of potential bearing surfacetreatments. Down-select promising approaches to friction and wear improvement. Design, build, and test a variable loading bearing test system.FY 2011: Variable load testing of the leading candidates coatings and treatments. Confirm plans for scale up of the concept validation in year 3, if fundingpermits.ACKNOWLEDGEMENTSSpecial thanks to D. Bansal and K. Cooley, ORNL, who assisted in tribo-testing,wear measurements, and VLBT apparatus construction.Wear tests and measurements were made on instruments in the DOE/EERE/OVTHigh Temperature Materials Laboratory (HTML), Tribology Research User Center.19Managed by UT-Battellefor the U.S. Department of Energy

Summary Improvements in surface properties and raw material cost reductions by emergingprocesses, enable new uses for lightweight Ti alloys in energy-efficient engines. Integral big-end bearing surfaces of connecting rods were selected to demonstratesurface engineering approaches and to eliminate lead-bearing bronze inserts fromvehicles. Other applications for Ti-based bearing surfaces are possible. A literature review, coupled with past OVT-sponsored ORNL tribology work, helpedidentify and down-select candidate surface treatments and coatings. Tests of 18candidates in FY 2010 (Phase I) revealed 8 with promising performance for furtherstudy in FY 2011 (Phase II). Following initial laboratory-scale screening tests of bare, treated, and coated Ticoupons, a variable load test system was designed and built to simul