Development of tribological PVD coatings Roberto M. Souza  . Laboratório de Fenômenos de Superfície Departamento de Engenh...
 
 
Outline <ul><li>Overview – Development of PVD coatings </li></ul><ul><ul><li>Ideas currently in use - Examples </li></ul><...
PVD <ul><li>Global value of PVD industry </li></ul><ul><ul><li>Data from 2007 </li></ul></ul><ul><ul><li>Predicted  annual...
Development of PVD Coatings <ul><li>Book chapter: O. Salas, J. Oseguera “Megatendencia: Ingeniería de Superficies” </li></...
Thin film development [Donnet & Erdemir Surf. Coat. Technol. v.257, 2004] <ul><li>Development in three main areas </li></u...
Examples – Materials and Structures <ul><li>Adaptive coatings </li></ul><ul><ul><li>Merging multiple complementary solid l...
Examples - Processing <ul><li>Pulsed Magnetron Sputtering (PMS) </li></ul><ul><ul><li>Use for the deposition of highly ins...
Examples - Processing <ul><li>Pulsed Magnetron Sputtering (PMS) </li></ul><ul><ul><li>Plasma monitoring  during </li></ul>...
Examples - Processing <ul><li>Pulsed Magnetron Sputtering (PMS) </li></ul><ul><ul><li>Ion energy and ion flux </li></ul></...
Examples - Processing <ul><li>High Power Pulse Magnetron Sputtering  – HPPMS </li></ul><ul><li>(also known as  High Power ...
Examples - Processing <ul><li>Modulated Pulse Power  – MPP </li></ul>[Courtesy: J.J. Moore, ACSEL, Colorado School of Mine...
Examples - Materials <ul><li>Materials – Nitrides and carbonitrides </li></ul><ul><ul><li>TiN, TiCN, CrN, ZrN, TaN </li></...
Surface Phenomena Laboratory <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characterist...
Residual Stresses <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characteristics Hardnes...
Residual Stresses in Thin Films <ul><li>Several reviews are available in the literature. Usually: </li></ul><ul><ul><li>Ef...
Residual Stresses in Thin Films <ul><li>Extrinsic stresses – In general, </li></ul><ul><li>Intrinsic stresses – Commonly d...
Residual Stresses in Thin Films <ul><li>Physical Vapor Deposition (PVD) films:  </li></ul><ul><ul><li>Different techniques...
Residual Stresses in Thin Films <ul><li>PVD films: </li></ul><ul><ul><li>Models to determine intrinsic stresses </li></ul>...
Residual Stresses <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characteristics Hardnes...
First set of TiN specimens Pulsed Magnetron Sputtering
First Set of TiN Specimens <ul><li>Set of specimens prepared with or without target pulsing (PMS) </li></ul><ul><ul><li>Re...
First Set of TiN Specimens <ul><li>However, film debonding if the film stresses were too compressive </li></ul><ul><li>Con...
Second set of TiN specimens Gradient stresses
Surface Phenomena Laboratory <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characterist...
Second set of TiN specimens <ul><li>Main idea: Prepare films grading the residual stress level – Control of deposition sub...
Second set of TiN specimens <ul><li>Idea poses two questions </li></ul><ul><ul><li>Question 1: How to measure the stress g...
Second set of TiN specimens <ul><li>Stress measurement – D2 substrates </li></ul>Increasing  bias Decreasing  bias Constan...
Second set of TiN specimens <ul><li>Stress measurement – M2 substrates </li></ul>Increasing  bias Decreasing  bias Specime...
Surface Phenomena Laboratory <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characterist...
Second set of TiN specimens <ul><li>Stress measurement – X-ray diffraction with grazing </li></ul><ul><li>incident angle <...
Second set of TiN specimens <ul><li>Stress measurement – X-ray diffraction with grazing </li></ul><ul><li>incident angle <...
Second set of TiN specimens <ul><li>Stress measurement – X-ray diffraction with grazing </li></ul><ul><li>incident angle –...
Second set of TiN specimens <ul><li>Stress measurement – X-ray diffraction with grazing </li></ul><ul><li>incident angle –...
Second set of TiN specimens <ul><li>Idea poses two questions </li></ul><ul><ul><li>Question 2: How to evaluate the tribolo...
Surface Phenomena Laboratory <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characterist...
Second set of TiN specimens <ul><li>Tribological behavior – M2 substrates </li></ul>–  Increasing bias –  Decreasing bias ...
Ensaios de Deslizamento – Pression Alta (2) <ul><li>Tribological behavior – Sliding test at high contact pressure </li></u...
Second set of TiN specimens <ul><li>Tribological behavior </li></ul><ul><ul><li>Conventional scratch test – Critical load ...
Second set of TiN specimens <ul><li>Tribological behavior – Sliding test at low contact pressure </li></ul><ul><ul><li>Pin...
Second set of TiN specimens <ul><li>Optical spectroscopy </li></ul>–  594 sectional profiles –  Average of profiles Increa...
Second set of TiN specimens <ul><li>Friction coefficient: Results similar to those in the literature for TiN   </li></ul><...
Second set of TiN specimens <ul><li>This study has shown </li></ul><ul><ul><li>Quick formation of a third body layer at th...
Concluding Remarks <ul><li>Discuss, with examples, some routes for the development of PVD coatings </li></ul><ul><li>Prese...
Acknowledgements <ul><li>FAPESP, CNPq, CAPES </li></ul><ul><li>Research groups – Actual experimental analysis </li></ul><u...
Second set of TiN specimens <ul><li>Tribological behavior – Tensile testing </li></ul><ul><ul><li>In theory, provides quan...
Second set of TiN specimens <ul><li>Evolution of specimen surface throughout the cycles </li></ul>« particles » Third body...
Second set of TiN specimens <ul><li>Fraction of “particles” and oxidized area  </li></ul>Trou Rupture
Second set of TiN specimens <ul><li>FEG: Field Emmission Gun -  Specimen </li></ul>Increasing bias, hole –  Observation of...
Second set of TiN specimens <ul><li>Pin  s urface </li></ul>Increasing bias Constant bias Rupture   Hole
Second set of TiN specimens <ul><li>Scanning electron microscopy-  Pin   </li></ul>Pol. Croissante - Trou
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Development of tribological PVD coatings

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Trabalho apresentado pelo prof. Roberto M. Souza (LFS-EPUSP) no 64o Congresso internacional da ABM, em Belo Horizonte (MG), em julho.

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Development of tribological PVD coatings

  1. 1. Development of tribological PVD coatings Roberto M. Souza . Laboratório de Fenômenos de Superfície Departamento de Engenharia Mec ânica Escola Politécnica da Universidade de São Paulo [email_address]
  2. 4. Outline <ul><li>Overview – Development of PVD coatings </li></ul><ul><ul><li>Ideas currently in use - Examples </li></ul></ul><ul><li>Thin film development at the Surface Phenomena Laboratory </li></ul><ul><ul><li>Measurement, tribological evaluation, film processing </li></ul></ul><ul><ul><li>Example – Film residual stresses </li></ul></ul>
  3. 5. PVD <ul><li>Global value of PVD industry </li></ul><ul><ul><li>Data from 2007 </li></ul></ul><ul><ul><li>Predicted annual </li></ul></ul><ul><ul><li>growth rate for </li></ul></ul><ul><ul><li>the next 5 </li></ul></ul><ul><ul><li>years: </li></ul></ul><ul><ul><li>11 % per year </li></ul></ul>[http://www.bccresearch.com/report/MFG015C.html]
  4. 6. Development of PVD Coatings <ul><li>Book chapter: O. Salas, J. Oseguera “Megatendencia: Ingeniería de Superficies” </li></ul><ul><ul><li>Question asked to a number of specialists: “… currently, surface engineering pushes or pulls the market? ” </li></ul></ul><ul><ul><li>Possible interpretation of the question: </li></ul></ul><ul><ul><li>What question occurs more frequently? </li></ul></ul><ul><ul><li> Developer to industry: I have developed this coating, would you test it for me? </li></ul></ul><ul><ul><li> Industry to developer: I need a coating with the following properties, would you develop one for me? </li></ul></ul><ul><ul><li>No clear trend in the answers </li></ul></ul>
  5. 7. Thin film development [Donnet & Erdemir Surf. Coat. Technol. v.257, 2004] <ul><li>Development in three main areas </li></ul><ul><li>This presentation </li></ul><ul><ul><li>PVD </li></ul></ul><ul><ul><li>Mostly hard coatings </li></ul></ul><ul><li>Recent developments </li></ul><ul><ul><li>Drive or driven by industrial needs? </li></ul></ul>
  6. 8. Examples – Materials and Structures <ul><li>Adaptive coatings </li></ul><ul><ul><li>Merging multiple complementary solid lubricants in a nanocomposite coating </li></ul></ul><ul><ul><li>Continuous response of the contact surface to the surroundings </li></ul></ul><ul><ul><ul><li>Load </li></ul></ul></ul><ul><ul><ul><li>Sliding speed </li></ul></ul></ul><ul><ul><ul><li>Environment </li></ul></ul></ul><ul><ul><ul><li>Temperature </li></ul></ul></ul>[Muratore & Voevodin Ann. Rev. Mat. Res. 39 ( 2009) 297-324]
  7. 9. Examples - Processing <ul><li>Pulsed Magnetron Sputtering (PMS) </li></ul><ul><ul><li>Use for the deposition of highly insulating materials </li></ul></ul><ul><ul><li>Reduction of arcing events </li></ul></ul>Al 2 O 3 films DC reactive sputtering Pulsed reactive sputtering [ P.J. Kelly et al. Surf Coat Technol 86-87 (1996) 28-32 ] [P.J. Kelly and D.R. Arnell, Vacuum 56 (2000) 159-172]
  8. 10. Examples - Processing <ul><li>Pulsed Magnetron Sputtering (PMS) </li></ul><ul><ul><li>Plasma monitoring during </li></ul></ul><ul><ul><li>the deposition of </li></ul></ul><ul><ul><li>Cr 1-x Al x N coatings for Al die </li></ul></ul><ul><ul><li>casting applications </li></ul></ul><ul><ul><ul><li>Ion flux </li></ul></ul></ul><ul><ul><ul><li>Ion energy </li></ul></ul></ul>[Courtesy: J.J. Moore, ACSEL, Colorado School of Mines ] Side View Top View Hiden electrostatic quadrupole plasma mass spectrometer (EQP) Al Cr
  9. 11. Examples - Processing <ul><li>Pulsed Magnetron Sputtering (PMS) </li></ul><ul><ul><li>Ion energy and ion flux </li></ul></ul>[J. Lin et al., Surface and Coatings Technology 201 (2007) 4640]
  10. 12. Examples - Processing <ul><li>High Power Pulse Magnetron Sputtering – HPPMS </li></ul><ul><li>(also known as High Power Impulse Magnetron Sputtering – HIPIMS) </li></ul><ul><ul><li>Highly ionized flux of sputtered material instead of large amount of neutrals </li></ul></ul><ul><ul><li>Low deposition rates </li></ul></ul><ul><li>Modulated Pulse Power – MPP </li></ul><ul><ul><li>Advantages of HPPMS </li></ul></ul><ul><ul><li>High deposition rates </li></ul></ul>
  11. 13. Examples - Processing <ul><li>Modulated Pulse Power – MPP </li></ul>[Courtesy: J.J. Moore, ACSEL, Colorado School of Mines ]
  12. 14. Examples - Materials <ul><li>Materials – Nitrides and carbonitrides </li></ul><ul><ul><li>TiN, TiCN, CrN, ZrN, TaN </li></ul></ul><ul><ul><li>TiAlN, TiSiN, TiAlCN, CrAlN, TiCuN, TiNbN, TiHfN, TiVN, TiZrN, TiMoN </li></ul></ul><ul><ul><li>TiAlSiCrN </li></ul></ul><ul><ul><li>TiAlVN, TiCrAlN, ZrCrAlN, TiAlNbN </li></ul></ul><ul><ul><li>Drive or driven by industrial needs? </li></ul></ul>
  13. 15. Surface Phenomena Laboratory <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characteristics Hardness Fracture Toughness Residual Stresses Adhesion Evaluation Modeling     Experimental     Analytical    Wear x characteristic   Material Processing   
  14. 16. Residual Stresses <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characteristics Hardness Fracture Toughness Residual Stresses Adhesion Evaluation Modeling     Experimental     Analytical    Wear x characteristic   Material Processing   
  15. 17. Residual Stresses in Thin Films <ul><li>Several reviews are available in the literature. Usually: </li></ul><ul><ul><li>Effects of thin film stresses </li></ul></ul><ul><ul><li>Measurement techniques </li></ul></ul><ul><ul><li>Sources </li></ul></ul><ul><li>Sources </li></ul><ul><ul><li>Classification. Different views in the literature </li></ul></ul><ul><ul><ul><li>Intrinsic: During deposition </li></ul></ul></ul><ul><ul><ul><li>Extrinsic: After the film growth step is concluded </li></ul></ul></ul>In the contents
  16. 18. Residual Stresses in Thin Films <ul><li>Extrinsic stresses – In general, </li></ul><ul><li>Intrinsic stresses – Commonly due to defects generated during deposition </li></ul><ul><li>Effect of intrinsic and extrinsic stresses </li></ul><ul><ul><li>Ratio between deposition and melting temperature T d / T m </li></ul></ul><ul><ul><li> vs. Adatom mobility </li></ul></ul>[J.A. Thornton, D.W. Hoffman, Thin Solid Films , 171 (1989) 5-31. ] PVD CVD
  17. 19. Residual Stresses in Thin Films <ul><li>Physical Vapor Deposition (PVD) films: </li></ul><ul><ul><li>Different techniques developed to achieve denser films, which have better tribological properties </li></ul></ul><ul><ul><li>Effect of ion bombardment – Structure zone models </li></ul></ul>T d /T m Evaporation [ B.A. Movchan, A.V. Demchishin, Phys. Met. Metallogr. , 28 (1969) 83-90. ] Close-field Unbalanced MS [ P.J. Kelly, R.D. Arnell, Vacuum , 56 (2000) 159-172 . ] T d /T m Sputtering [ J.A. Thornton, Ann. Rev. Mater. Sci. , 7 (1977) 239-260. ]
  18. 20. Residual Stresses in Thin Films <ul><li>PVD films: </li></ul><ul><ul><li>Models to determine intrinsic stresses </li></ul></ul><ul><ul><ul><li>Windischmann (1987,1992): Stresses are directly proportional to the flux of energetic particles arriving on the substrate and to the square root of their kinetic energy. </li></ul></ul></ul><ul><ul><ul><li>Davies (1993): Thermal spikes to reduce stress by causing displacement of the implanted atoms. </li></ul></ul></ul><ul><li>Conventional MS </li></ul><ul><li>Davis’ model </li></ul><ul><li>Unbalanced MS </li></ul><ul><li>Davis’ model </li></ul>[ Y. Pauleau, Vacuum 61 , 2001, 175-181 ]
  19. 21. Residual Stresses <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characteristics Hardness Fracture Toughness Residual Stresses Adhesion Evaluation Modeling     Experimental     Analytical    Wear x characteristic   Material Processing   
  20. 22. First set of TiN specimens Pulsed Magnetron Sputtering
  21. 23. First Set of TiN Specimens <ul><li>Set of specimens prepared with or without target pulsing (PMS) </li></ul><ul><ul><li>Residual stresses increased with applied bias and with PMS </li></ul></ul>[ M. Benegra et al. Thin Solid Films 494 (2006) 146-150 ] <ul><li>Micro-scale abrasion tests </li></ul><ul><ul><li>Overall trend of wear reduction with the increase in film stresses </li></ul></ul>[ R.C. Cozza et al. Surf. Coat. Technol. 201 (2006) 4242-4246 ]
  22. 24. First Set of TiN Specimens <ul><li>However, film debonding if the film stresses were too compressive </li></ul><ul><li>Confirm literature data that compressive film residual stresses may be beneficial as long as film/substrate adhesion is not impaired </li></ul>
  23. 25. Second set of TiN specimens Gradient stresses
  24. 26. Surface Phenomena Laboratory <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characteristics Hardness Fracture Toughness Residual Stresses Adhesion Evaluation Modeling     Experimental     Analytical    Wear x characteristic   Material Processing   
  25. 27. Second set of TiN specimens <ul><li>Main idea: Prepare films grading the residual stress level – Control of deposition substrate bias </li></ul><ul><li>Previous works in the literature </li></ul><ul><ul><li>Fischer and Oettel, Surf. Coat. Technol. 97 (1997) </li></ul></ul>Reduce wear Improve adhesion [ E. Uhlman & K. Klein , Surf. Coat. Technol. 131 (2000) ] <ul><ul><li>Stress graduation obtained </li></ul></ul><ul><ul><li>based on the control of the </li></ul></ul><ul><ul><li>pressure during the deposition </li></ul></ul>
  26. 28. Second set of TiN specimens <ul><li>Idea poses two questions </li></ul><ul><ul><li>Question 1: How to measure the stress gradient </li></ul></ul><ul><ul><ul><li>TiN films obtained in hybrid reactor after plasma nitriding </li></ul></ul></ul><ul><ul><ul><ul><li>Triode magnetron sputtering deposition </li></ul></ul></ul></ul><ul><ul><ul><ul><li>D2 substrates </li></ul></ul></ul></ul><ul><ul><ul><ul><li>M2 substrates </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Substrate bias increasing, decreasing or constant </li></ul></ul></ul></ul>
  27. 29. Second set of TiN specimens <ul><li>Stress measurement – D2 substrates </li></ul>Increasing bias Decreasing bias Constant bias Specimen Layer Time (min) Bias (V) G1D2 1 45 -20 2 45 -40 3 45 -100 4 45 -150 5 45 -200 G2D2 1 45 -200 2 45 -150 3 45 -100 4 45 -40 5 45 -20 S1 1 120 -20 S2 1 120 -40 S3 1 120 -100 S4 1 120 -150 S5 1 120 -200
  28. 30. Second set of TiN specimens <ul><li>Stress measurement – M2 substrates </li></ul>Increasing bias Decreasing bias Specimen Layer Time (min) Bias (V) G3M2 1 45 -20 2 45 -40 3 45 -80 4 45 -100 G4M2 1 45 -100 2 45 -80 3 45 -40 4 45 -20
  29. 31. Surface Phenomena Laboratory <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characteristics Hardness Fracture Toughness Residual Stresses Adhesion Evaluation Modeling     Experimental     Analytical    Wear x characteristic   Material Processing   
  30. 32. Second set of TiN specimens <ul><li>Stress measurement – X-ray diffraction with grazing </li></ul><ul><li>incident angle </li></ul><ul><ul><li>Results of “single layer” </li></ul></ul><ul><ul><li>thin films: S1 to S5 </li></ul></ul><ul><ul><li>Agreement with literature </li></ul></ul>
  31. 33. Second set of TiN specimens <ul><li>Stress measurement – X-ray diffraction with grazing </li></ul><ul><li>incident angle </li></ul><ul><ul><li>How to measure the gradient? </li></ul></ul><ul><ul><li>Idea: H. Dolle, J. Appl. Cryst. 1979 </li></ul></ul><ul><ul><li>mean value of residual stress over </li></ul></ul><ul><ul><li>a depth x </li></ul></ul> 1  2  3  4  5
  32. 34. Second set of TiN specimens <ul><li>Stress measurement – X-ray diffraction with grazing </li></ul><ul><li>incident angle – D2 substrates </li></ul><ul><ul><li>Use values of the single layers </li></ul></ul><ul><ul><li>to calculate value measured </li></ul></ul><ul><ul><li>with X-ray diffraction </li></ul></ul> 1 ,  2 ,  3 ,  4 ,  5 
  33. 35. Second set of TiN specimens <ul><li>Stress measurement – X-ray diffraction with grazing </li></ul><ul><li>incident angle – M2 substrates </li></ul><ul><ul><li>Use values of the single layers </li></ul></ul><ul><ul><li>to calculate value measured </li></ul></ul><ul><ul><li>with X-ray diffraction </li></ul></ul> 1 ,  2 ,  3 ,  4 
  34. 36. Second set of TiN specimens <ul><li>Idea poses two questions </li></ul><ul><ul><li>Question 2: How to evaluate the tribological behavior </li></ul></ul><ul><ul><ul><li>Pin-on-disk testing </li></ul></ul></ul><ul><ul><ul><ul><li>High contact pressure </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Low contact pressure </li></ul></ul></ul></ul>
  35. 37. Surface Phenomena Laboratory <ul><li>Tribological (wear, friction) behavior of thin films </li></ul>Thin Film Characteristics Hardness Fracture Toughness Residual Stresses Adhesion Evaluation Modeling     Experimental     Analytical    Wear x characteristic   Material Processing   
  36. 38. Second set of TiN specimens <ul><li>Tribological behavior – M2 substrates </li></ul>– Increasing bias – Decreasing bias – Constant bias – Differences in curvature: initial bias determined the curvature even if the average bias value was equal Increasing Const. Decr.
  37. 39. Ensaios de Deslizamento – Pression Alta (2) <ul><li>Tribological behavior – Sliding test at high contact pressure </li></ul><ul><ul><li>Pin: Steel, R = 5 mm </li></ul></ul><ul><ul><li>Track length = 10 mm </li></ul></ul><ul><ul><li>Frequence: 10 mHz (v = 0.2 mm/s) </li></ul></ul><ul><li>F x t (Pressão x t): </li></ul><ul><ul><li>1 cycle </li></ul></ul><ul><ul><li>200 à 400 N (2,8 à 3,5 GPa) </li></ul></ul><ul><ul><li>150 à 350 N (1,7 à 3,3 GPa) </li></ul></ul>
  38. 40. Second set of TiN specimens <ul><li>Tribological behavior </li></ul><ul><ul><li>Conventional scratch test – Critical load for adhesive failure </li></ul></ul><ul><ul><ul><li>Increasing bias: 16.2 ± 1.8 N </li></ul></ul></ul><ul><ul><ul><li>Decreasing bias: 3.1 ± 0.2 N </li></ul></ul></ul><ul><ul><li>“ Non-conventional” scratch test: Steel spherical stylus (R = 5 mm), </li></ul></ul><ul><ul><li>increasing normal load from 150 to 400 N (Nominal Hertz P max from </li></ul></ul><ul><ul><li>1.7 to 3.4 GPa) </li></ul></ul>Constant Increasing Decreasing
  39. 41. Second set of TiN specimens <ul><li>Tribological behavior – Sliding test at low contact pressure </li></ul><ul><ul><li>Pin: Steel, R = 100 mm </li></ul></ul><ul><ul><li>Track length = 3 mm </li></ul></ul><ul><ul><li>Frequence: 100 mHz (v = 0.6 mm/s) </li></ul></ul><ul><ul><li>F x t (P. Max Hertz x t): </li></ul></ul><ul><ul><li>150 cycles </li></ul></ul><ul><ul><li>50 N (0,24 GPa – P Max Hertz) </li></ul></ul>Hole ( trou ) Rupture
  40. 42. Second set of TiN specimens <ul><li>Optical spectroscopy </li></ul>– 594 sectional profiles – Average of profiles Increasing bias Constant bias Decreasing bias Increasing 100 nm 100 nm 100 nm Track width
  41. 43. Second set of TiN specimens <ul><li>Friction coefficient: Results similar to those in the literature for TiN </li></ul><ul><ul><li>High friction coefficient values </li></ul></ul><ul><ul><li>High values from the first cycles </li></ul></ul><ul><ul><li>All films behaved similarly </li></ul></ul>
  42. 44. Second set of TiN specimens <ul><li>This study has shown </li></ul><ul><ul><li>Quick formation of a third body layer at the pin surface and high friction coefficient </li></ul></ul><ul><ul><li>Gradual oxidation of the specimen surface </li></ul></ul><ul><ul><li>Negligible wear of the specimens </li></ul></ul><ul><ul><li>Similar behavior in all cases </li></ul></ul>
  43. 45. Concluding Remarks <ul><li>Discuss, with examples, some routes for the development of PVD coatings </li></ul><ul><li>Present an overall organization of the study of the tribological behavior of thin films – driven by the market </li></ul><ul><ul><li>Emphasize necessity of accurate measurement and the importance of the choice in tribological testing </li></ul></ul>
  44. 46. Acknowledgements <ul><li>FAPESP, CNPq, CAPES </li></ul><ul><li>Research groups – Actual experimental analysis </li></ul><ul><ul><li>LFS – Esc. Politécnica USP </li></ul></ul><ul><ul><li>ACSEL – Colorado School of Mines, USA </li></ul></ul><ul><ul><li>TMI – INSA-Lyon, France </li></ul></ul><ul><ul><li>IPEN </li></ul></ul><ul><ul><li>Inst. Física – USP </li></ul></ul><ul><ul><li>CNEA, Argentina </li></ul></ul><ul><li>Plus valuable discussions with many other groups </li></ul>
  45. 47.
  46. 48. Second set of TiN specimens <ul><li>Tribological behavior – Tensile testing </li></ul><ul><ul><li>In theory, provides quantitative results in terms of film fracture toughness and film/substrate adhesion </li></ul></ul>Catastrophic failure before significant plastic deformation of the substrate Film fracture was not observed during the test Impossible to compare the deposition conditions F F
  47. 49. Second set of TiN specimens <ul><li>Evolution of specimen surface throughout the cycles </li></ul>« particles » Third body oxidation First body
  48. 50. Second set of TiN specimens <ul><li>Fraction of “particles” and oxidized area </li></ul>Trou Rupture
  49. 51. Second set of TiN specimens <ul><li>FEG: Field Emmission Gun - Specimen </li></ul>Increasing bias, hole – Observation of iron oxyde on track surface: Free and agglomarated particles
  50. 52. Second set of TiN specimens <ul><li>Pin s urface </li></ul>Increasing bias Constant bias Rupture Hole
  51. 53. Second set of TiN specimens <ul><li>Scanning electron microscopy- Pin </li></ul>Pol. Croissante - Trou
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