Tribological Challenges in Flex Fuel Engines
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Invited lecture of the Simposium N "Surface Engineering - functional coatings and modified surfaces" at the XIII SBPMat (Brazilian MRS) meeting, in João Pessoa (Brazil). The lecture took place on September 29th, 2014. The speaker was Prof. Amilton Sinatora (Escola Politécnica da USP, São Paulo state, Brazil).
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Tribological Challenges in Flex Fuel Engines
- 1. TRIBOLOGICAL CHALLENGES IN FLEX FUEL ENGINES 1 Amilton Sinatora 29/09/2014
- 2. Topics 2 1. The TRIBOFLEX consortium 2. Selected topics on engine tribology
- 3. São Paulo University Ribeirão Preto Pirassununga Bauru Lorena São Paulo São Carlos Piracicaba State University São Paulo State Soutwest Brazil Created in 1934 72 unities: including • 37 colleges • 4 museums • 4 hospitals
- 4. São Paulo University Item 1989 2012 % Students Under. 31 897 58 303 + 83 MsC 8 486 13 836 + 63 Dr. 4 428 14 662 + 231 Total 44 811 86 801 + 100 Academic 5 626 5 860 + 4 Stu/acad 8:1 15:1 Staf 17 735 16 839 - 5 Feb. 2016! ~1986
- 5. Polytechnic School - 1893 in numbers · Created in 1893 · Absorved by USP in 1934 · 24 buildings with 152.500 m2 · 15 Engineering departments · 447 Scholar (-2,5% 2009) · 103 laboratories · 4.700 undergraduated students · 791 master degree students (2013) · 761 doctoral students (2013) · 5% increase total students 2009 -2013
- 6. Mechanical Engineering Department In numbers · 51 Scholars · 13 laboratories · 70 undergrad.
- 7. The Surface Phenomena Laboratory in numbers Created in 1994 · 07 Scholars · 04 Pós doc fellows · 14 doctoral students · 09 master degree students · 06 Senior reseachers · 08 undergraduated students · 03 technicians · 02 administrative support
- 8. Pós Doc Fellows Erika, Tiago, André, Tomanik Doctoral Students Ana Júlia, Vanessa, Pablo, Guilherme, Gil, Eduardo, Eleir, Felipe, Juan, Roberto, Alexander, Franco, Jimmy e Paulo Master Degree Students Marcio Silva, Andre, Luigi, Marcio, Renata, Tiago, Arthur, Gustavo e Iramar Senior Researches Marcos, Philip, Cristiano, Luiz, Manuel, Newton Undergraduated Students Felipe, Vinicius Campos, Fernando, Henrique, Vinicius, Lucas, Edemar e Arthur Technicians Raquel, Fabio e Francisco Administrative Support Silene e Sidney Academic Tanaka, Izabel, Roberto, Amilton, Mario, André, Rodrigo
- 9. 1. Project history and scope 2. TRIBOFLEX starts 3. Project structure 4. Project status 5. Project outcomes 6. Project chalenges 9 1. The TRIBOFLEX consortium
- 10. 1 .Scope /History - 2009 There was a perception that the Brazilian Flex fuel engines had relevant tribological challenges. Such challenges are peculiar and important both to the industry and academy. Ago 2009 – Workshop at MAHLE The project joining competitors has pre-competitive scope and a strong focus to education on combustion engine tribology. Such human resources should be able to support the R&D on engines using bio-fuels, both in the industry and the P&D centers. 10 Rings: Premature wear spalling Gustavo Volci ME 2007 UFPR Valves: Leakage power loss.
- 11. 11 Erdermir, 2012 1 .Scope /History Worldwide trend to reduce fuel consumption. Brazil INOVARAUTO Erdermir 2012 The Project scope was defined through several workshops with both automotive companies, suppliers and universities. The project content was also defined by the companies interests, participants expertise, budget and rules to be partially funded by the Government funding agency (FAPESP). The project wasexpect to last 3 years, 1.2 Mi R$/year, about 100 k R$ per company participant per year Large part of the engine energy is lost to overcome friction
- 12. 1 .Scope /History - 2009 – 2012 Legal/bureaucratic PARKOUR Workshps. Scope - focus - expert ise - int eress- funding Technical workshops. Companies - universit ies - suppliers - invited speakers FAPES. Projec evaluat ion / aproval / signature USP Legal procedure / revision of t he project / adjust budget Companies - USP inovat ion agency - FAPESP 2009 2010 201 1 2012 12
- 13. 1 .Scope /History - 2009 – 2012 Legal/bureaucratic PARKOUR Universities Inexperienced to deal with complex projects considering the legal, technical and management aspects (First USP consortium) Legal/ bureaucratic. It was necessary to adapt the procedures to the paperwork. Inexperienced to fulfill the FAPESP formal requirements of the FAPESP support program portfolio; Technical. Fundamental knowledge however, lack of experience and technical expertise in the field; Management. Previous experience with one-to-one project, academic network projects. No experience with supplier-costumer nor competitor-competitor projects. FAPESP The same …(First FAPESP consortium) Legal/ bureaucratic. The routine to evaluate the consortium was the same used to evaluate one-to-one-partner projects. Reviewers complained on the percentage of FAPESP X companies financial contribution. Some suggested that the project should be fully supported by the companies. Technical. Reviewers complained: Must include senior person from automotive field. The deliverables of the project were ill defined. There are no clear technical benefit to the companies nor to the market…. Consortium scope and organization did not adjust to any of FAPESP or USP previous procedure Approval was only achieved due to the commitment of the companies, FAPESP and USP. 13
- 14. 2 . TRIBOFLEX Starts ....and then,... Tupy joins the consortium!! Legal/bureaucratic PARKOUR Universities - FAPESP Inexperienced to deal with complex projects considering the legal, technical and management aspects (First time that a newcomer (new partner) joins the first USP / FAPESP consortium!) 14
- 15. 3 . TRIBOFLEX Structure Project contribution if successful Structured knowledge on tribology focused in: - tribological coatings (films and oxides) - texturing / topography on engine components - affinity between lubricants and components (films and materials) Structured knowledge in the modelling and experimental analysis of the tribo-systems - ring/lube/bore - valve/interfacial media / valve seat Multi scale (centimeter to nanometer). Multidisciplinar (chemistry, material science, metallurgy, mechanical engineering). Multi skill (mathematical, computational, experimental). 15
- 16. 3 . TRIBOFLEX Structure Four macro-projects 00- Tribological Characterization of flex-fuel engine components 0.01 – Wear mechanism on worn parts 01- Ring-Lube-Bore Tribo system (sl 17) 1.01 – Graphite and bore wear mechanisms 1.02 – Physicochemical interaction of oxides and lube film 1.03 – Lubricity of degraded oils and the ring materials 1.04 – Low friction films for piston rings 02- Valve-interfacial media-valve seat tribology 2.01 – Topography and tribological performance of valves 2.02 – Influence of temperature and frequency on wear 2.03 – Valve bench tests for valves and valve seats 2.04 – Metal and ceramic materials for valves 03- Modeling of materials and loadings 3.01 – Modeling of materials / films under thermal /mechanical loads 3.02 – Modeling ring/bore friction under lubrication 04 – Education of specialized human resources 4.01 - Road Show to attract talents for the project 4.02 – Courses for basic formation on engine tribology 4.03 – Graduate studies for regular employees from companies 4.04 – Doctor thesis on topics related to the macro-projects 4.05 – International experts Expresses broad companies interests. Themes were set after 2009 workshops Expresses mostly the academic expertise and/or on going research X 16
- 17. 3 . TRIBOFLEX Structure – Engine systems Ring – Lube - Bore Valve - Seat Supplier commitment and expertise Relevant to the auto companies
- 18. 3 . TRIBOFLEX Structure Four macro-projects 00- Tribological Characterization of flex-fuel engine components 0.01 – Wear mechanism on worn parts 01- Ring-Lube-Bore Tribo system (sl 17) 1.01 – Graphite and bore wear mechanisms 1.02 – Physicochemical interaction of oxides and lube film 1.03 – Lubricity of degraded oils and the ring materials 1.04 – Low friction films for piston rings 02- Valve-interfacial media-valve seat tribology 2.01 – Topography and tribological performance of valves 2.02 – Influence of temperature and frequency on wear 2.03 – Valve bench tests for valves and valve seats 2.04 – Metal and ceramic materials for valves 03- Modeling of materials and loadings (sl 18) 3.01 – Modeling of materials / films under thermal /mechanical loads 3.02 – Modeling ring/bore friction under lubrication 04 – Education of specialized human resources 4.01 - Road Show to attract talents for the project 4.02 – Courses for basic formation on engine tribology 4.03 – Graduate studies for regular employees from companies 4.04 – Doctor thesis on topics related to the macro-projects 4.05 – International experts Expresses broad companies interests. Themes were set after 2009 workshops Expresses mostly the academic expertise and/or on going research X 18
- 19. 3 . TRIBOFLEX Structure – Modeling + Experimental 2 Tribo tests 3 Topography analysis 4 Surface chemistry 1 Characterization and properties
- 20. 3 . TRIBOFLEX Structure Industry x academy Supplyer x customer Competitor - competitor 5th Steering comitee USP 27/03/2014 12th Tech. Meeting USP 27/03/2014 Multiscale Multidisciplinar Theoretical x experimental 2nd Int. Course USP 02-03/10/2013 Background courses to the participants 20
- 21. 4. Project Status First Master in Engineering Dissertation fully developed in the TRIBOFLEX consortium. 13-03-2014. Eduardo Trindade PETROBRAS Project plan 2009 Project submission dec. 2009 Contract final version: dec. 2012 First report sept 2013 Second report sept 2014 Next steps Final report sept 2015 First Doctor Engineering Thesis fully developed in the TRIBOFLEX consortium. 11- 06-2014. Ane Cheila Rovani (now at UFPR) 21
- 22. Such human resources should be able to support the R & D on engines using bio-fuels, both in the industry and the P&D centers. Industry R & D staff education 1 ME sudent 1 Dr student TRIBOFLEX 1 ME sudent 1 Dr student 1 Engineer 1 Tecnician 1 Dr student Two years research project 1 Pos Doc Fellow 1 Dr Student 5 . Outcomes 22
- 23. The project has pre-competitive scope and a strong focus to education of human resources on combustion engine tribology 1st Course on Tribology of Automotive Components. Recife 14 -18th july 2014 1 Undergraduate student 1 Dr student 1 Academic TRIBOFLEX 1 Academic 5 . Outcomes 23
- 24. 6. Project Chalenges / future Daily topics Complex projects demands time consuming management and control: Provide resources to hire specialists (chief engineer, administrative staff) http://www.eusci.org.uk/ articles/what-happens-when- scientist-becomes- manager) Long term topics Legal – bureaucratic issues: Help to build new procedures Companies x University mindset: work together and solve. 24 Knowledge gap (university and companies) is large: Intensify and improve the international cooperation A lot of information and knowledge is produced: Provide resources to knowledge management. Communicate the project to the members and the society Find nice themes to TRIBOFLEX II
- 25. 2. Selected topics on engine tribology - On going research -
- 26. 2. Selected topics on engine tribology 2 Tribo tests 3 Topography analysis 4 Surface chemistry and 1 Characterization properties 2.1 Bore characterization 2.2 Bore wear measurement 2.3 Friction and wear tests 26
- 27. Ring and Bore after Global Engine Durability 450 h Wide Open Throttle 2.1 CHARACTERIZATION – RING - BORE New E 20 E 100 Dinécio Santos Filho / Hélio Goldenstein Carbonaceous deposits E85 Bore Piston (ring pack + pin region) Brigheter regions (both motors) Top dead center (TDC)
- 28. 2.1 CHARACTERIZATION – RING - BORE Honned bore surface Top and side view Grooves Folded metal E 20 E 100 E 85 / E100 Top dead center. Vertical scratches. Residual honning grooves, folded metals Vertical grooves – abrasion marks top dead center Dinécio Santos Filho / Hélio Goldenstein
- 29. 2.1 CHARACTERIZATION – RING - BORE TDC Mid stroke BDC Vertical grooves abrasion marks along the bore height TDC transverse section. Squeeze graphite and cracks. Metallic wear debris due to fatigue process. Dinécio Santos Filho / Hélio Goldenstein TDC Mid BDC Summit and core wear 28
- 30. 2.1 CHARACTERIZATION – RING - BORE New E 20 E 100 Ring wear more intense in the ethanol engine test Dinécio Santos Filho / Hélio Goldenstein Expand the characterization (check) Quantify the wear (in a easy way) Estimate the energy loss due to vertical scratches Evaluate ring and cylinder material microstructure and properties Improve the computer model piston piston ring Cylinder wall Combustion chamber lubricant lubricant 30
- 31. 2.2 Cylinder bore wear measurement Rafael Obara TDC Mid Stroke BDC Literature: Superpose the Abbot Firestone curves using the maximum height frequency as criterium Cabanettes 2012 Cast iron cylinder liner 31
- 32. TDC 2.2 CHARACTERIZATION Quantify the wear Worn Unworn BDC 1. Obtain a 3D profile (9h work!) 2.Obtain a 2D profile (height profile) 3. Remove 10% summits 4. Calculate average value from each 1024 measurements 5. Calculate relative height = (hunworn – hworn) ! 2D wear estimative! (Blue) 6. Find a literature model (Green) 7. Build your own statistic Vmc model (Red) 8. Compare both with the relative height Rafael Obara 2014 R2 = 0,6 R2 = 0,4
- 33. 2.2 CHARACTERIZATION Ring x bore and valve x valve seat characterization 33
- 34. 2.2 Friction and wear measurements - Mixed lubrication - Mixed Lubrication 2.2.1 How are we measuring 2.2.2 Effect of anisotropy 2.23 Material – base line 2.2.4 Material - maleable 2.2.5 Material – deep etching 2.2.6 Additives + nano 34
- 35. 2.2.1 How are we measuring? Ball on plate Oil dropletes ASTM D 6425. 52100 ball x 52100 disc Polished 2 h, 50 Hz, 300 N. tests 50, 80, 120, 15°C Optimol SRV Tribometer Round robin Eduardo D. Trindade Alexander Zuleta D. test – 2013 40 labs duplicated results, ASTM D6425-05 (friction and wear) Repeatability – r Reproducibility - R 35
- 36. 2.2.1 How are we measuring? LFS results plotted vs normalizad average friction coefficient round robin results Our COF results < 2σ ! 36
- 37. 2.2.1 How are we measuring? COF (group average) Repeatability r = 0,01 Reproducibility R = 0,03 3 Oils COF ~ 0,13 r 0,12 to 0,14 R 0,10 to 0,16 A better oil (surface treatment, material, roughness) should result in COF max 0, 10! 37
- 38. 2.2.2 Effect of TOPOGRAPHY Anisotropy Ball (SAE 52100 700HV30) on disc (H13 610 HV30) Ball Roughness < 0,050 μm Ball radius 5 mm Reciprocating 10Hz, 35N Max speed 90mm/s SAE 5W30 K viscosity @40C 60,1cSt K viscosity @100C 10,5cSt Parameter Average 8 spots 'Sa' 0,345 'Sq' 0,450 'Ssk' 0,491 'Sku' 4,754 'Sp' 2,233 'Sv' 1,334 'Sz' 3,567 'Vm' 0,030 'Vv' 0,569 'Vmc 0,377 'Vvc' 0,521 'Vvv' 0,048 Strong effec of topograpy orientation on avg COF besides the roughness Vinicius Campos Tiago Cosseau parameter are the same.
- 39. 2.2.2 Effect of TOPOGRAPHY Anisotropy COF along a stroke and ball displacement with time. Speed is zero at the broken lines (end of stroke) and it is maximum at the mid point. COF scale is not centered on zero COF is almost constant – blue line Boundary lubrication behaviour. 39
- 40. 2.2.2 Effect of TOPOGRAPHY Anisotropy t(s) 600,05 600,15 Green and blue COF measured paralel to the milling grooves. Straight lines (boundary lubrication) Red and light blue COF measured perpendicular to the milling groves – The COF increases at the edges of the wear scar (boundary lubrication). Minimum COF (mixed lubrication)
- 41. 2.2.2 Effect of TOPOGRAPHY Anisotropy COF Experimental x calculated COF both orientation. Calculated: Deterministic model (hidrodinamic and asperity pressures) to calculate lubricant and asperity shear stresses). μ boundary from measurement 4- Mixed regime model (deterministic) Build a 2D model Consider topographic change with time Test with plain oil (at the same viscosity) to check boundary COF contribution Better boundary COF to the model 41
- 42. 2.2.3 Bore and ring materials friction and wear base line piston ring bore Marcos Ara Nitreded stainles steel ring Ring x bore sample asembly Gray cast iron bore 64 samples extracted from engine block + ring pa F: 50N , 20Hz Stroke: 2.5 mm T: 25 C Oil: PAO Fully floded Surface: Milled t: 6, 60, 600 min 42
- 43. t (min) log t (min) COF ~ 50% COF reduction Δ = 0,05 > R – smoother surface? Steady satate friction after 10 h?
- 44. 2.2.3 Bore and ring materials friction and wear base line Overal wear rate Wear rate each test period. Wear steady state after 60 min in advance to COF steady state Param New 6 min 60 min 600 min Sa (mm) 0.23 0.029 0.19 0.039 0.17 0.021 0.16 0.024 Sq (mm) 0.30 0.039 0.24 0.053 0.22 0.027 0.22 0.057 Ssk (mm) -0.95 0.400 -1.23 1.756 -0.60 0.573 -1.17 1.329 Sku (mm) 5.73 2.580 17.59 28.89 7.62 4.419 11.48 11.06 Sp (mm) 1.25 0.306 1.14 (.075 1.03 0.333 1.22 0.488 Sv (mm) 2.55 1.036 3.08 1.818 2.57 0.675 2.94 1.432 Sz (mm) 3.79 1.093 4.27 2.351 3.60 0.674 4.14 1.451 Main texture changes within 6 min test g/m g/m log t (min) log t (min) COF controlled by a tribofilm or by the ring wear
- 45. 2.2.4 Bore and ring materials friction and wear Graphite morphology + (residual carbide, martensite) COF F: 50N , 20Hz Stroke: 2.5 mm T: 25 C Oil: PAO Fully floded Surface: Milled t (s) Shorter running in period COF maleable iron in the boton range Lower wear after 1hr. Same avg COF after 1 hr Paulo Ogata COF Ring x (grey or) maleable iron – 5 tests each. 45
- 46. 2.2.5 Bore and ring materials friction and wear Deep etched cast iron Deep etch after milling Deep etch after polishing Lazer interferomety. Deep etched after polishing gray cast iron. COF t (s) Shorter running in period COF values milled + deep etch in the boton range COF polished + deep etched lower than COF range in the running in period Raquel Camponucci F: 50N , 20Hz Stroke: 2.5 mm T: 25 C Oil: PAO Surface: Milled t: 6, 60, 600 min 46
- 47. 2.2.6 additives + nano particles A MoDTC + PAO + Ester COF increases with F B Stearic acid + PAO + Ester COF decreases with F C NanoMag – Stearic + PAO COF decreases with F D Frunkim Isotherm ~ A & B Boundary lubrication COF models Eduardo Trindade - Ane Rovani - André Zuin 47
- 48. Some remarks 1/4 - MINIMIZE RUNNING IN (LESS DEBRIS) - RESIST TO PRESSURE AND TEMPERATURES New engine more boudary and mixed lube regimes Mixed Lubrication 2014 Results. Running in reduction 2014 Results. COF decreases with F 48
- 49. Some remarks 2/4 - LOWER THE COF ALL LUBRICATION REGIMES 2014 Results. PAO, PAO Nano MAG, 5W30, maleable iron. COF 0,15 – 0,10 2014 Results. Texture, deep etch Mixed Lubrication 49
- 50. Some remarks – Chalenges 3/4 - COF 0,05 – 0,02 -COF lower than 0,01 Mixed Lubrication Tribl Int. 65 (2013) 28-36 50
- 51. Some remarks – Chalenges 4/4 - COF 0,05 – 0,02 -COF lower than 0,01 Mixed Lubrication v increse v decrease COF COF + water t min 51
Editor's Notes
- Good morning ladies and gentlemen. Thank you for joinning this presentation. I would like to share some of our experience in mannaging the TRIBOFLEX consortium and also to show some preliminary results we produced so far.
- I will follow those toppics starting with some words about my university
- The São Paulo university is a very large state university. It is 80 years old and has ~70 unities most of them located in São Paulo city as you can see at the picture
- I will use my life time at USP to show some numbers. The number of undergraduate studentes increased by 83% and the overal student numbers is twice it was in the eighteens. At the same time frame the number of staff members decreased by 5% and the academic staf is today 4% greater than it was 89. We became very productive as you can see when the number of students per academic is considered.
- My institute is the Polytechnic school that is older than the university iteself. Here you can see some numbers and is remarkable that the number of academic experienced some decrease from 2009 besides the total student number as increase 5%.
- The mechanicla engineering department is as old as the Politch scholl and since the beggining of the 20th century there were studies related to the use of ethanol as fuel to car engines. Left you can see the eng. Oliveira at the Sugar and Alcool Institute in Rio de Janeiro where he came back to Politech Scool to teach engines and combustion whit enphasis in the use of ethanol as a fuel to cars
- There you can see some of our studentes in the leizure time and after the first PhD thesis on the scope of the TRIBOFLEX consortium
- We are at them moment with around 60 persons at our laboratory de aling with 3 main projects, one with gears and gear boxes (leaded by Izabel Machado, the second on Modeling tools leaded by Roberto Martins and the TRIBOFLEX CONSORTIUM that i will say some words in the next few minutes.
- I will follow THOSE topics startig with a brief description of the project history and scope.
- The main topics to be highlighted here are that we have the feeling that there were some relevant tribological problems with the FLEX FUEL engines mainly between valve and valve seats. We considered also that a project joining competitors should have a PRE COMPETITIVE SCOPE and finally that the FOCUS has to be on EDUCATION on combustion engine TRIBOLOGY
- However....We had to surpass a complex bureaucratic system to achieve the project approval. Here in green the time spent to create the project and we can compare it with the time we spent with the mainly formal and legal activities described in pink red and blue. The chronogram also reports the technical meetings we promoted.
- Some of our difficulties were: the lack of experience to deal with complex projects considering at the same time the legal, technical and management aspects. The lack of experience and technical expertise on ENGINE tribology besides we had a good fundamental knowledge. However , what I consider that was the greatest difficultie was to adjust the project needs to the formal USP and FAPESP procedures. It is necessary to say that the project aproval was only achieved
- And then, later on, when TUPY JOINED the project we needed to start everething again because it was the first time that a newcomer joined such a project
- In paralel wiht bureaucratic / legal difficulties the projec is technically complex.
- To achieve those goals we set four macro projects that expresses broad company&apos;s interests that were set after the 2009 workshops. Those macro projects were split in a number of small projects that came from on going research or previous academic expertise. And here we have some residual stress to be relieved once the academic themes are not (in my opinion) clear enough to all the participants.
- We are studiing thwo tribosystmes. Ring x cilinder bore and valve x valve seat. Each one of them has its onw strenghts. On the left side we do have a strong commitment of the suppliers and expertise that was develloped since the 90teens. On the right side we do have equipments from lab to engine scale and recently we concluded na equipment powered by eletric motors that allow us to study in full scale the design properties of the valves.
- To achieve those goals we set four macro projects that expresses broad company&apos;s interests that were set after the 2009 workshops. Those macro projects were split in a number of small projects that came from on going research or previous academic expertise. And here we have some residual stress to be relieved once the academic themes are not (in my opinion) clear enough to all the participants.
- Lazer 3D measuremente – film thickness+ hidrodinamic pressure + cavitation + metal to metal pressure (area), all deterministic i.e considering fluid mechanics over the real surface. Then VTL – Virtual Tribol Lab (lfs site) Finally FMEP – Friction Mean Efective Pressure
- A way to deal with such a complex consortium was to promote technical meetings with specific subjects, backgroud courses to the participants and to bring international especialists to help us with more advanced themes.
- Currently we are near the second report to FAPESP and we start to graduate students. The two pictures are from the first master dissertation and from the first TRIBOFLEX doctor thesis. The project is planed to be conclude next year.
- Other important out come, full in alingnement with the project scope, is that the number of students that are coworkes from the consortium companies is increasing. We have now 6 engeniers from the consortium companies studiyng for thesis or dissertations and we have just signed a two years research project together with PETROBRAS to suport the thesis research program.
- Finally i would like to highlight that we are spreading out our still limited skills on engine tribology over some research groups outside São Paulo State
- To conclude this tI wpic, I woul bring in this slides some other topics to debate.
- I will present those three topics. One example of characterization, a study on engine cylinder bore mesurement and some results of friction and wear tests
- 2 Engines after 450 hours. Full power. In the first row we can see how a new ciliyder bore and piston looks like. At the samples testes with gasohol a stark carbonaceous deposit is visible. The ethanol fueled engide show more clean parts. It is quite usual. A gaz powered engine would be more clean than the others.
- At the upper lef figure you can see a new honned surface cast iron cylinder wall. The right figure shows a side view of the honned cilinder. The lower row showh for both gasohol and ethanol for the TOP DED CENTER that the honning marks are somewat worn out and that are a lot of vertical scratches.
- At the left de you can see pirctures acros the height of the cilynder. Highlights are the scratches along the height and the smooth surface at BOTTON DEAD CENTER where the oil rings are. At the right side we can see how after 450 h the material is to be removed. There are cracks propagating to the surface from the graphite veins what would eventualy lead to mater soial removal. At the boon you can see how some topographic parameters evolved. 2D measurements. Decrease in the peek hight and in some case the fulfillemente of valleys, probably with folded metal.
- T the ring cylinder bore tibosystem there are a lot to do
- It is very difficult to measure or even estimate the wear at the cylinder. The mass loss is very small and the piece has to be sliced to be weighed. There are few attempts to measure the wear by optical means. There we have na example of the literature where the author alings the most frequent value of the abbot firestone curve in order to stablish a reference to both new and worn surface. In order to subtract then. Even when a cylinder liner is used.
- Vmc (Volume of material at the core roughness region). The average value is a good estimation of the worn material. However it takes a lot of time to make the measurements. Is is increasingly used to measure the bores in mass production. Eg. VW.
- To conclude this topic on characterization is worth to say that 3 graduated students are working on the theme. We did or we are doing the same for the Valve seat
- Now we enter in the friction and wear measurements. The results that will be presented are concerned to piston ring system where boudary, hydrodinamic and mixed lubrication occurs. Mixed is a lubrication regime where it hapens partialy the full film lubrication (hydrodinamic) and partially the so called boudary lubrication where the chemical nature of the lubricant plays a decisive role. Teh figure left show some targets of COF for lubrication regimes in cars.
- In orde to now if we are realy measuring something we took part of a ....The conditions are detailed above. With some remarks of important aspects.
- The slide shows how the normalized COF of our tests performed agaist the 40 labs. Not bad. Oil 2 was for us the one wit larger scatering.
- THE POINT TO STRENGTH For the oil tested any improvemente should lead to COF lower than 0,10
- In this study we are proposing a way to evaluate the contribution of the texture to the COV values and also doing a crytical experiment to evaluate wich set of surface parameters are able to inform about the surface performance. We have the test conditions. The midle figure shows the AVERAGE COF. For both directions. Vmc – core mean volume
- COF along a stroke. In each half stroke the ball speed reaches a maximum in the midle of the track. The seed the decrease reaching zero at the border of the track. Notice that the friction coefficient is almost constant for the blue line (paralel to the machining lines). Coef has max value at the end of the stroke for the red line. Perpendicular to the machining marks.
- Red and light blue lines. COF increases at the end of the stroke. MIXED REGIME lubrication
- Here are the comparison of experimental and calculated results. There are a lot to do to check if
- 64 samples. 4 cylinder, 4 heights, 4 angles. Gray cast iron vs Stainles steel ring nitreded. The purpose of the study is to stablish a base line of COF and wear rate results considering standard materials at both sides, body and counter body. test was again a reciprocating one. In the lef you can see the experimental set up. The cast iron flat is a gray cast iron with flake graphite and in the midle we can see that the the wear scar is much more larger than the microstructure and the machinning marks.
- At the right side of the picture you can see the COF at the first 6 min of the test. There were a increase and oscilation in the COF along this period that we call RUNNING IN. In the midle it is the results of 1 hr test We can see that there are some oscilation up to aroun 600 s and then the COF decrease almos steadily, In the large picutre the 10hr tests results are dispalyed. And we can see that the COF is steel decreasing. In the upper lef part of the figure we have the average value of the last hundred seconds of each teste periodo. Each log test period thre is a decrease in COF similar to R. 6 mim vc 600 min 30% COF reduction. Cause. Smoother surface? Roughenes parameter do not coroborate that. Directional wear? The texture is in the wrong direction as we will see soon.
- The wear rate decreased strongly with time. When calculate the wear rate at each test period we can see that after 1hr it remains almost the same. The surface parameters also changes strongly in the first test period and after that thy oscilate. The small clocs at the left side indicates that in the first 6 min the texture experienced a strong change with
- Here we have the effect of changing the material. The gray cast iron was replaced by a malleable iron where the graphite is more dispersed and it was obtainede by the decomposition of cementite. The overal result of harder matrix, residual carbides and graphite morphology is quinte impressive over the running in period. It occurred a les intense running in, and the COF value after one hour is in the range of the base line material. As a consequence of reduced running in intesity the wear was strongly reduced. Um dos pontos a medir é a perda de massa em 6 min.
- eThere you can see a speculative result obtained only exposing the graphite by means of a laboratory deep etch procedure. In both case (polished and milled )surface, the running in amplitude was reduced and for the polished samples the COF value was bellow the 0,1 range.
- At the picture in the lefe side the COF increased with preasure in ball on disc tests wher PAO was mixed with ester oil and MoDTC. At the right side the result is just the opposite. The COF decreased in pin on disc tests where the disc was covered witha a monolayer of stearic acid. The lowest COF were obtained when Magnetite was detected over the disc surface. Below in the right side, you can see tha we are too dealing with nano things. Here we draw a nano particle of Magnetite covered with a layer of stearica acid. By chance we had the same effect, that is when the normal load was increased the COF decreased and (in experiments not show in the slide) the running in decreased. At the right side of the slide the proposed model for COF as a function of boht ester os stearic acid contents.
- To smm up I woult to repeat some of the topics, focusing some aspects that are very relevante to the automakers and their supliers. In this slide the running in reduction (intensity, amplitude, length) and the desireble effect of COF reduction with applied load.
- The tird aspect I woul to include in the summary de desireble COF reduction in all lubrication regimes. And in this silide I stress that during this year we have been working on the set up mainly with PAO a oil without aditives and even so we were able to get values of COF bellow 0,1.
- The range of COF between 0,05 and 0,01 is attracting the attention of some companies. They are searchig for ways tor functionalize the surface of engines components in order to profit better form the engineered molecules that are to be (or are under development). In this slide we can see a nice example of COF at the border ~0,05 obtainde with syabean oil with additon of CuO or ZnO. I find those more polar base oils a promissing way to reduce friction on the range below 0,05.
- This last slide shows the COF expected range to all friction componentes of the 2020 engine. There are scarce results of COF below 0,01 in lubricated systems with oil. It is belived that engineered molecules that produce repulsive electrical forces are candidate to reduce friction in the boundary + mixed regimes at this COF range. To give na examplo I show you some results we obtained with ceramics under sliding rotative tribo tests where we were able to measure COF bellow 0,01. I belive that we can go further on to values lower than 10-3. That is for the moment and I hope that in the next and last TRIBOFLES year we will be able to produce mor colplete results and meet again to share some of them. THANK YOU FOR YOUR KIND ATTENTION