Thin solids  										  films of 304L stainless steel are  										  prepared by the ion beam sputtering  										  technique. The obtained films present  										  a debonding phenomenon and a high  										  compressive stress state. The critical  										  stress value causing the debonding  										  phenomenon is determined using atomic  										  force microscopy (AFM). By ion beam  										  assisted deposition (IBAD) process  										  during the films elaboration, we  										  observe a stress relaxation. This  										  effect is measured using the X-ray  										  diffraction method sin2Ψ.Thin solids  										  films  of 304L stainless steel are  										  prepared by the ion beam  sputtering  										  technique. The obtained films present  									 	  a debonding phenomenon and a high  										  compressive stress  state. The critical  										  stress value causing the debonding  			 							  phenomenon is determined using atomic  										  force  microscopy (AFM). By ion beam  										  assisted deposition (IBAD)  process  										  during the films elaboration, we  										   observe a stress relaxation. This  										  effect is measured using  the X-ray  										  diffraction method sin2Ψ

Abouzaid, A.

Boubeker, B.

Goudeau, Ph.

Idiri, M.

Laaroussi, S.

Renault, P.O.

Talea, M.

English

Thin solids  										  films  of 304L stainless steel are  										  prepared by the ion beam  sputtering  										  technique. The obtained films present  									 	  a debonding phenomenon and a high  										  compressive stress  state. The critical  										  stress value causing the debonding  			 							  phenomenon is determined using atomic  										  force  microscopy (AFM). By ion beam  										  assisted deposition (IBAD)  process  										  during the films elaboration, we  										   observe a stress relaxation. This  										  effect is measured using  the X-ray  										  diffraction method sin2Ψ.Thin solids  										  films of 304L stainless steel are  										  prepared by the ion beam sputtering  										  technique. The obtained films present  										  a debonding phenomenon and a high  										  compressive stress state. The critical  										  stress value causing the debonding  										  phenomenon is determined using atomic  										  force microscopy (AFM). By ion beam  										  assisted deposition (IBAD) process  										  during the films elaboration, we  										  observe a stress relaxation. This  										  effect is measured using the X-ray  										  diffraction method sin2Ψ

Revues Scientifiques Marocaines

M. J. CONDENSED MATTER                                      VOLUME 6, NUMBER 1                                          1 JANUARY 2005Evaluation Of The Damage In The Stainless Steel Coatings By Residual StressMeasurementS. Laaroussi*, B.Boubeker*, M. Talea*, M. Idiri*, A. Abouzaid*, P.O. Renault**, Ph. Goudeau***Université Hassan II – Mohamedia, Faculté des Sciences Ben M’Sik, Département de Physique, UFR: MilieuxDenses et Matériaux, B.P 7955 Sidi Othman , Casablanca, Maroc**Université de Poitiers, UFR Sciences, S.P.2M.I, Laboratoire de Métallurgie Physique, URA 131 du CNRS, Bd 3,Téléport 2, BP. 179, 86960 Futuroscope cedex, FranceThin solids films of 304L stainless steel are prepared by the ion beam sputtering technique. The obtainedfilms present a debonding phenomenon and a high compressive stress state. The critical stress value causingthe debonding phenomenon is determined using atomic force microscopy (AFM). By   ion beam assisteddeposition  (IBAD)  process  during  the  films  elaboration,  we  observe  a  stress  relaxation.  This  effect  ismeasured using the X-ray diffraction method sin2Ψ.              Keywords: Stainless steel films; Residual stresses; X-ray diffraction; Atomic force microscopyI - INTRODUCTION:Sputter-deposited  films  are  largely  studied.  Oneparticular  characteristic  of  these  layers  is  thedevelopment  of  high  residual  compressive  stressesduring the deposition process [1,2].Due  to  the  presence  of  such  large  residualcompressive  stresses,  the  films  debond  from  thesubstrates,  and  present  interesting  topographicalpatterns [3].Concerning  the sputter-deposited 304 stainless steel(SS) films, their structural, mechanical properties andadhesion behaviour, have been already studied usingX- ray diffraction, transmission electron microscopy(TEM), scanning electron microscopy (SEM) and X-ray diffraction sin2ψ method [3,4,5]. In the other hand,the wear and corrosion behaviours of  304 SS filmswere examined. In comparison with a bulk 304 L SS,an improvement of the wear and corrosion resistanceis observed [6,7].This  work  is  devoted  to  complete  the  studyconcerning the 304 L SS coating layers produced byion beam sputtering technique.The  first  part  of  this  paper  is  concerned  with  thebuckling phenomenon observed in 304  L SS films.The study is  performed using the SEM and atomicforce  microscopy  (AFM)  techniques.  The  observedwrinkles are examined, and critical stress producingdebonding  phenomenon  is  obtained  usingcalculations  based  on  the  phenomenological  modeldeveloped by J. W.Hutchinson [8]. The  second  part  is  devoted  to  study  the  ion  beamassisted  deposition  (IBAD)  effect  on  the  structuraland  mechanical  properties  of  304  L  SS  preparedusing the ion beam sputtering technique. During thedeposition process, the ion beam sputtering techniquecan be  associated to  assistance by ions  of  rare  gasduring a film growth. This can allow modifying thestress  state  in  the  film,  often  responsible  to  thedebonding phenomenon. In our study, tree kinds ofion  irradiation  with  25,  50  and  75µA  in  focalisedcurrents respectively were performed.  We apply X-ray  diffraction  (XRD)  technique  to  determine  theresidual stresses ? and stress- free lattice parameter a0.II - EXPERIMENTAL PROCEDURE1 - Films preparationThin  304  L  SS  films  were  deposited  at  roomtemperature  using  an  Ar  ion  beam  sputteringtechnique.  The  sputtering  system  was  alreadydescribed in details in reference [9]; let us recall here,the deposition conditions and parameters:- The pressure witch start at 2 x 10  –  6 Torr,was maintained around 5 x 10 – 4 Torr duringthe deposition.- The deposition rate was equal to 0.05 nm s-1.- The films thicknesses  were  successively inrange  of  60 to  600  nm.  The  thickness  ischosen as a function of the technical analysismethod used and/or the studied effect.- The  deposition  rate  and  films  thicknesseswere controlled by a quartz oscillator.- The  used  substrates  were  successively,silicon  wafers  and  polycarbonate  inparallelepiped form.- The sample-holder temperature, was limited(less  than  350K)  during  the  depositionprocess.6   100  2005 The Moroccan Statistical Physical and Condensed matter Society101           S. LAAROUSSI, B.BOUBEKER, M. TALEA, M. IDIRI, A. ABOUZAID, P.O. RENAULT, PH. GOUDEAU          62  -  Buckling  phenomenonobservationsThe spontaneous debonded regions of the films wereobserved using a Jeol scanning electron microscope,and a specific Atomic Force Microscope coupled to acompression machine has been used to follow in situthe emergence of buckling and debonded regions ofthe films under axial stress. This apparatus has beendescribed in reference [10]. The wrinkles dimensionswere measured using a DEKTAK profilometer.3 - Stress determination  X-ray  experiments  for  residual  stresses  wereperformed  on  a  beam line  D22  of  the  synchrotronradiation  LURE  at  Orsay  using  an  originaldiffractometer  developed  in  LMP  (Laboratoire  deMétallurgie  Physique)  de  Poitiers,  France  [11]  anddedicated to nanocrystalline material studies,  with awavelength of 0.2137 nm and ?  configuration [12].Stress determination was performed using the well-known  sin2ψ method.  This  method  is  based  on  themeasurement of the shift of diffraction peak positionrecorded for different Euler angles [13].In this study, we have followed the evolution of the(211) peak position of the bcc structure as function ofthe  angle  ψ.  Experimental  data  have  been  analysedwhen  considering  an  in-plane  isotropic  stress  state(?11 =  ?22 =  ?11  and  ?33= 0)  and  using  the  rationaldefinition of strains [14].( ) ++Ψ= θσσθ 0122 sin1ln 2 21 sin1ln SsinShkl      (1)where, ?hkl stand for diffraction angle of (hkl) plane,?0 is the stress-free diffraction angle and between thesurface normal and diffracting plane normal. The X-ray elastic constants (XECs) values used are the oneof  ?-Fe  based  materiel  calculated  by  the  self-consistent method of Kroner-Eshelby [15]:  1/2 S2  =5,71x10-3 GPa-1 et  S1  =  -1,12x10-3 .  For  cubicmaterials, this method always gives results, which arein  good  agreement  with  experimental  values  [16].When plotting Ln (1/sin?) as a function of sin2ψ, oneget a straight line (eq.1), its slope is related to the in-plane stress ?,  and it’s origin ordinate to the stress-free lattice parameter a0 [17,18].III - EXPERIMENTAL RESULTS ANDDISCUSSIONa- The buckling phenomenon study1 - AFM observations under applied stressAs mentioned in previous work [19], using an AFMapparatus,  coupled  to  a  compression  machine,  abuckling regions were observed in the 304 SS filmsdeposited  on  polycarbonate  substrate.  The  filmstudied  here,  has  a  thickness  of  60  nm,  and  nospontaneous  wrinkle  is  observed  before  thecompression test.  This can be observed in figure 1,where the initial state of the film is presented. A scheme representing the compressive test is givenin the figure 2.After uniaxial compressive stress, the film presents adebonding  phenomenon.  The obtained final  state ofthe  film  after  a  whole  cycle  of  compression  ispresented in the figure 3. The buckles obtained herepropagate  in  sinusoidal  form.  This  propagationgrowth in the perpendicular direction to the uniaxialapplied  stress.  The  apparition  of  this  phenomenonhappened  when  the  applied  stress  equal  a  criticalvalue of 0.33 GPa.  2  -  Spontaneous  debonding  phenomenonobservationsWhen the film thickness exceed a value about  140nm, a spontaneous buckling phenomenon is observed.Different and various forms and shapes of debondedregions are observed.In  figure  4,  we  observe,  the  first  state  of  thespontaneous  debonding,  the  shape  of  the  blisterspresents various forms.The  stress  effects  can  be  observed  in  the  figure  5.Under the internal stresses, the blister shape evolutioncan  be  followed.  The  debonding  phenomenonindicates  the  compressive  nature  of  the  stress.  Theobtained  blister  is  circular  and  stays  in  this  form.There is no propagation of the debonded part of thefilm, but  the blister  submitted to  the internal  stressgrowth,  and the final result  of  this evolution is  theapparition of cracking into the blister (two holes intothe observed blister presented in figure 5). This mayindicate that the internal compressive stress has manydirections.  The  other  forms  of  spontaneous  bucklingphenomenon  may  observed.  In  the  figure  6,  thedebonded region presents a sinusoidal buckling. Theapparition  of  the  same  form  of  buckling  in  onedirection,  indicate  a  possible  existence  of  uniaxialcompressive internal stress.  As  mentioned  in  previous  works  [3,19],  thisphenomenon  is  related  to  the  internal  stressesdepending on the film thickness.Let us now determine the critical stress value witchgave rise to the spontaneous debonding phenomenon.Using  the  J.W.  Hutchinson  model  [8],  the  criticalstress value can be obtained from the relationship:  σc= 1,22 [ E / ( 1 - ν )]( h / R )2 where:E  :  is  the  Young  modulus  of  the  film,  ν :  is  thePoisson’s ratio of the film, 6                            EVALUATION OF THE DAMAGE IN THE STAINLESS STEEL COATINGS …                102 h :  is  the  film  thickness,  R :  is  the  radius  of  thedeflexion of the film as presented in the figure 7.The parameter’s values are successively: E  =  145GPa [20] and ν = 0,3If we consider the radius average value, witch equal12.5  nm,  using  the  relationship  given  above,  weobtain the critical value σc = 0.31 GPa. This value canbe  compared  well  with  the  value  obtained  underapplied  stress  (0.33  GPa).  This  is  the  stress  witchallows the initiation of the delamination in the film.However  to  obtain  internal  residual  stress  σ in  thefilm, the X-ray diffraction technique is until now, thebetter used method. The results may be found in thefollowing part.Figure 1: The initial state of the film with out anywrinklesFigure 2: Scheme representing the compressive testFigure 3: Final state of the film showing the bucklingphenomenon in one directionFigure 4: Spontaneous debonded regions in differentformsFigure 5: The evolution of the blister: apparition ofcracking in the blister    Compressive deformatioCompressive deformatiSubstrateFilm103           S. LAAROUSSI, B.BOUBEKER, M. TALEA, M. IDIRI, A. ABOUZAID, P.O. RENAULT, PH. GOUDEAU          6Figure 6: Spontaneous debondiong showing apropagation in sinusoidal formsb – The stress study by the X-ray diffractionThe  experimental  values  deduced  from  X-raymeasurements  are  reported  in  table  1.  For  the  asprepared films the obtained value (-3.20 GPa), showsthe  high  compressive  state  of  the  film.  The  ion-assisted  process  strongly  influences  the  stressmagnitude.  Indeed,  it  induced  a  great  stressescompressive relaxation.The origin of such a high magnitude of stress in thinfilms deposited on substrate can be explained by twomodels based on volume expansion due to energeticparticle bombardment during deposition [21].The  lattice  expansion  effect  responsible  forcompressive stress is  clearly shown in table 1.  Thestress-free  lattice  parameters  (a0)  found  are  greaterthan  the  ferrite  bulk  stainless  steel  given  in  theliterature  [22].  On  the  other  hand,  the  stress  free-lattice  parameters  measured  on  assisted  films  arelower than those of as prepared film (a0 = 0.2888 nm).This implies an elimination defect in films crystallinedomains with assistance. The same phenomenon wasobserved by Goudeau et  al  [23]  in 304 L SS filmsdeposited  on  a  silicon  substrate  by  ion  beamsputtering  technique  and  assisted  during  depositionwith an Ar+ energy of 160 keV.Figure 7: Schematic view of circular blisterFigure 8: Evolution of the Ln 1/sinθ as a function ofsin2ψ   (The stress value is determined from the sloopof the straight line)IV. CONCLUSION:First, in this work, we have presented the debondingphenomenon, which happened in the 304 L SS filmselaborated  by  ion  beam  sputtering  technique.  Theresulting  buckling  exhibit  blisters  and  sinusoidalforms.  This is  attributed  to  the existence  of  a  highcompressive  internal  stresses  in  the  films.  Takingadvantage  to  its  high  resolution,  we  have  used  theAFM  to  analyse  the  first  stage  of  the  debondingphenomenon, and the obtained results were comparedquite to the Hutchinson’s model calculations used inthe case of the spontaneous debonding phenomenon.  We have also, remark that the stress direction can beuniaxial or multiaxial given arise to different forms ofbuckling.  The  origin  of  this  behaviour  will  beexplored in the further study.In  the  second,  we  have  shown  that  the  residualstresses  (responsible  of  the  buckling  patterns)  areconsiderably  reduced  when  using  IBAD processes.This is allows to consider the possibility to obtain astress-free state of the 304 L SS films (films with outdebonding), by using an IBAD processes. 0.0880.0920.0960.10.1040.1080 0.1 0.2 0.3 0.4 0.5 0.6 0.7ln(1/sinΘ)sin2(Ψ) 6                            EVALUATION OF THE DAMAGE IN THE STAINLESS STEEL COATINGS …                104 __________[1] N. Matuda, S. Baba, A. Kinbara -Thin Solid Fims81 (1981) 301 [2]  G. Gille,  B.  Rau -Thin Solid  Films 120  (1984)109 [3]  J.P. Eymery, B. Boubeker-  Materials Letters 19(1994) 137[4]  B.  Boubeker,  J.-P.  Eymery,  M.-F.  Denanot,E.L.H. Sayouty, J. Magn. Magn. Mater. 133 (1994)470.[5]   B.  Boubeker,  P.  Goudeau,  A.  Serrari,  J.P.Eymery,  Nucl.  Instr.  Meth.  B 155 (3)  (1999)  289–294.[6] M. Idiri, B. Boubeker, R. Sabot, Ph. Goudeau, J-F.  Dinhut  and J-L. Grosseau-Poussard,   Surf.  Coat.Technol, 122 (1999) 230-234.[7]  B.  Boubeker,  J.P.  Eymery,  Ph.  Goudeau,  K.Bouslykhane and J.P Villain Ann. Chim. Fr, 19(1994)377-382[8]  J.  W. Hutchinson,  M.D. Thouless,  E.G.  Liniger-Acta Metall. et Mater. 40,2 ( 1992) 295 [9]  M.  Jaulin,  G.  Laplanche,  J.  Delafond  and  S.Pimbert-Michaux,  Surf.  Coat.  Technol.,  37  (1989)225.[10]  C. Coupeau, Thèse de l’université de Poitiers,France, 1997.[11]  Ph.  Goudeau,  K.F.  Badawi,  A.  Naudon,  M.Jaulin,  N.  Durand,  L.  Bimbault  and  V.  Branger,  J.Phys. IV 6 (1996) 187-196.[12] V. Branger, D. Thesis, Poitiers, France[13] G.Maeder, Chem. Scrip., 26A (1986) 23-31.[14]  K.F. Badawi, C. Khaloun and J. Grilhé, J. Phys.III France 3 (1993) 1183 – 1188[15]  E.  Kroner,  Z.  Phys.,  151  (1958)  504 ;  J.D.Eshelby, Progr. Solid Mech., 2 (1961) 89.[16] L. Castex, J.L. Lebrun, J.M Spravel,  Pub. Sci.Tech. ENSAM, Paris (1981).[17]  Ph.  Goudeau,  B.  Boubeker,  J.P.  Eymery,  V.Branger, Thin solid films 275 (1996) 188.[18]P.  Goudeau,  A.  Serrari,  B.  Boubeker,  J.P.Eymery, Jour. ofHigh. Temp. Mater. Pro. 2 (1998) 431.[19]  M.  Talea,  B.  Boubeker,  F.  Cleymand,  C.Coupeau,  J.  Grilhé,  Ph.  Goudeau,  Materials Letters(1999) 181 - 185 [20]   B.  Boubeker,  M.  Talea,  Ph.  Goudeau,  C.Coupeau,  J.  Grilhé,  Materials  characterization  45(2000) 33 – 37[21]  E.S.  Machelin,  Materials  science  inMicroelectronics, Gyro Press, NY, 1995.[22]  S.  Harjo,  Y.  Tomota,  M.  Ono,  FourthInternational Conference on residual stresses, Vol 1,June 16 – 18, 1997 Linkoping, Sweden[23] N. Durand,  L. Bimbault,  K.F. Badawi and Ph.Goueau, J. Phys. III. 4 (1994) 1025Tables:SamplesFilmThicknes(nm)Focalisedcurrent(µm)Assistancerate(%)? ± ? ?(GPa)a ± ? a(nm)As-prepared235 00 0.00 -  3.20± 0.290.2888  ±0.0003A25 235 25 0.18 -0.70± 0.070.2880  ±0.0001A50 280 50 0.37 0.66  ±0.110.2882  ±0.0001A75 300 75 0.55 -2.75± 0.180.2883  ±0.0002Table 1:  Evolution of residual stress and lattice freeparameter as a function of assistance rate

Evaluation Of The Damage In The Stainless Steel Coatings By Residual Stress Measurement

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Evaluation Of The Damage In The Stainless Steel Coatings By Residual Stress Measurement

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