 adhesion of a ceramic TBC, while a denser coating will improve the corrosion and oxidation performance of the coating over the operational life cycle of the part. In order to achieve the required surface finish and a desired density, the coated article is worked by one or a combination of controlled mechanical techniques that include impinging the surface of the article with particles of preselected size for a preselected time and intensity to provide a smoother surface finish and hopefully improved density of the parts without adversely affecting the brittle coating material. While the mechanical techniques have been used for other applications, they have not been used to improve the surface finish of stoichiometric NiAl coatings applied to turbine airfoils. In order to apply these techniques to brittle stoichiometric NiAl, certain process controls are required to prevent damage to the coating. The present invention utilizes steel balls of preselected size to peen the surface of the airfoil to achieve the desired surface finish of at least 120 micro-inches. Desirably, the peening also densifies the coating.
And while the present invention was developed for use with stoichiometric NiAl which is brittle, it may be used advantageously with any other coating with an unacceptably rough surface finish due to application techniques and that is inherently brittle, but which requires a smooth surface finish for proper performance. Typically, these coatings have a higher Al content than other, more ductile coatings and are identified as beta phases, and the coatings contain a substantial amount of the beta phases or are primarily beta phases.
An advantage of the present invention is the ability to tailor the surface roughness of a brittle, substantially stoichiometric NiAl coating. In this way, the inherent advantages of a substantially stoichiometric NiAl composition can be utilized, while the brittle nature of the stoichiometric composition can be overcome so that the surface finish of the article can be modified to achieve the same results currently achievable with non-stoichiometric compositions that are either low in Ni or low in Al.
Another advantage of the present invention is the ability to increase the density of the brittle coating without damaging it. Thus, the present invention can modify the as-sprayed coating to achieve the required surface finish and desired density in order to take advantage of the improved corrosion and oxidation capabilities of the smoother, denser coating without damaging the brittle coating. The airfoils that have had their surface finish modified in accordance with the present invention have a more aerodynamic gas flow path that serves to
adhesion of a ceramic TBC, while a denser coating will improve the corrosion and oxidation performance of the application over the functional life sentence cycle of the character. In orderliness to achieve the required surface ending and a hope density, the coated article is worked by one or a combination of controlled mechanical techniques that admit impinging the surface of the article with particles of preselected size for a preselected time and volume to provide a smoother surface finish and hopefully improved concentration of the parts without adversely affecting the brittle coating fabric. While the mechanical techniques have been used for other applications, they have not been used to better the surface finish of stoichiometric NiAl coatings applied to turbine airfoils. In orderliness to apply these techniques to brittle stoichiometric NiAl, certain process controls are command to prevent damage to the coating. The present invention utilizes steel balls of preselected size to peen the surface of the airfoil to achieve the desired surface finish of at least 120 micro - inches. Desirably, the peening besides densifies the application. 
 And while the present invention was developed for use with stoichiometric NiAl which is brittle, it may be used well with any early coating with an unacceptably rough surface finish due to application techniques and that is inherently brittle, but which requires a smooth open finish for proper performance. Typically, these coatings have a higher Al content than early, more ductile coatings and are identified as beta phases, and the coatings contain a substantial amount of the beta phase or are primarily beta phases. 
 An advantage of the present invention is the ability to tailor the surface roughness of a brittle, well stoichiometric NiAl coating. In this way, the inherent advantages of a substantially stoichiometric NiAl composition can be utilized, while the brittle nature of the stoichiometric composition can be overcome so that the airfoil finish of the article can be modify to achieve the same results presently achievable with non - stoichiometric compositions that are either low in Ni or low in Al. 
 Another advantage of the present invention is the ability to increase the concentration of the brittle coating without damaging it. therefore, the present invention can modify the as - sprayed coating to achieve the required airfoil finish and desired density in order to take advantage of the improved corrosion and oxidation capabilities of the smoother, denser coating without damaging the brittle application. The airfoils that have had their open finish modified in accordance with the present invention have a more aerodynamic gas flow way that serves to
 adjesion of a ceramic TBC, dhile a denser eiating will jmprove ghe corrosion and oxidation 'erfirmanxe of the coating over the operwtional oife xycle of tis part. Lu ordsv to cciieve the requited surface xinish and a daskrzd density, the coated article is worhed by pnf or a combinajion ps cohnrilled mechanical techniques tgat incnude impinginb the surface of the articpe wlth particles of pgeselected wize dor a preseldcted time and intensijy to provide a smoother surface finixh and hopgyyllj improved dxnsity of the parts withoud adverxely affecting thx bruttle coating materian. While the mechanycal techtisues have been uswd for mthes apooicxtiknx, fhey hwve not been hsed to impeove the surface fimify of stoichiojetric NyAl coatings applied to turbine airfoilv. Ih order to apply these rechniques to brittle stoichioietric NiAl, certain process controls are required to pcexenu eamagd tl the coating. The present invention utilizes ffetl nalls of preselegted size to peen yhf xorface of the xirfoil tk achieve the desiged sursace dinish of at keast 120 micro-inches. Desirablt, the peeniny aoso densifies the eoating.
And wkile tne prrsent invention was devzloped for use wihh stoichjumetric NiAl whizh ps bsittle, iu may be used advagtageouslb witk any otfer voatind with an knaccc[tably rough surfafe fiuish gue to apppication techniques and that is inherently brotdle, but whieh reqmires a smooth furface finish for prjper oerformancv. Typicalny, these cowtings have a jigher Al coitent thag otyer, nore duzgile coatings snd are ibtntified aw beta phases, and bhe cuztings contain c wubstantial amoint of tje bqda phases or are prkkarilh beta kkascs.
Av adfantage of the presett ihvention is the abollty to taulor the surface rougnness of a brittle, subsvantiauly syoishiometric NiAl coating. In thia way, the inmerent advantwges of a substautially stoichiometric NiAl composition ran be utilized, while jhe brittle nature of uhe stoichiomxtric sompositimn can be overcome si that the surfact finish of the article can ba modlfied to achieve the same results currently achievable with non-stoichiomerric compositions fhat are vitker low ig Ni ur low in Al.
Anotner advantage of the present intention is tke ability to increase the demskty of the brkttle coating without dajaging iy. Thus, the present invention cam modify the as-sprayed cpating ti achjeve the rxquired surface finixh and desieed denwity in order to gakr wdvantage of uhe nmproved corrosion and oxidation xapabioihies of the smoovher, denser goxting withoot damaging the bdittmf coajing. The airfools that have nad their surface fitifh modified in zccordance woth the present invxntion have d more aerodynamic gas flow path that serves to
adhesion of a ceramic TBC, while a will the corrosion oxidation performance of life of the part. order to achieve required surface finish and a desired the coated article is worked by one or a combination of controlled mechanical that include impinging the surface of the article with particles of preselected size a time intensity provide a smoother surface finish and hopefully improved density of the parts without adversely affecting the coating material. While the mechanical techniques have been for other applications, they not been used to improve surface of stoichiometric coatings to airfoils. In order apply these techniques to brittle stoichiometric NiAl, certain process controls are required to prevent damage to the The present steel balls preselected to the surface of to achieve the desired surface finish 120 micro-inches. Desirably, the peening also densifies the And while present invention was developed for use stoichiometric NiAl which is brittle, it may be advantageously with any other coating with an unacceptably rough surface finish due to application techniques is inherently brittle, but requires a smooth finish proper Typically, coatings have higher Al content than other, more ductile coatings and are identified beta phases, and the coatings contain a substantial amount of phases are primarily beta An advantage of the invention the ability to tailor roughness a NiAl In way, the inherent advantages a substantially stoichiometric NiAl composition be utilized, while the composition can be overcome so that the surface of the article can be modified to the same results currently achievable with non-stoichiometric compositions that are either low Ni or Al. Another advantage of the present invention is ability to increase the of the brittle coating without damaging it. Thus, the invention modify the coating to achieve required surface finish desired density in take advantage the corrosion of the smoother, denser coating without the coating. The airfoils that have their modified in accordance with the present invention have a more aerodynamic gas flow path that
 adhesion of a ceramic TBC, whilE a denser coAting WilL imPrOve tHe coRrosion and oxidATion Performance of the coatinG over ThE OperATiOnal lIfe cyclE Of THE paRt. in OrdEr TO aChievE thE requirEd surface fIniSh And a desired dENsIty, the coatEd aRticle is workEd bY one or A cOmbINatioN of ContrOlled mEChanicAl techniqUeS That inCLude impINGiNg thE surface of the artiCLe WIth particles of PreselEcTEd SIZe fOr a PreselecteD tIme anD IntensiTY tO PROviDE a smoother surFace finish aND hoPefullY iMprOVed denSity oF tHE paRts without aDverSely affecTing thE Brittle COating mAteriaL. WhIle The mEChAnIcaL tEChnIQuEs hAVe bEen used fOr OtHer apPlicATIONs, thEy hAve nOt beeN used to improvE thE surFAce FinisH of stOichIoMetriC NiAl cOatinGs Applied to turbinE airFoils. In orDer To AppLy These TEchniqUes To bRittle sToichioMEtrIc nIaL, cErtain process contrOlS ARe Required To prevENt DaMAge to the CoAtiNg. ThE PResenT invENtIon utiliZes steEL bAlLs of preSeLected SiZe tO peEn the SUrfaCe of thE airfoil To achIEve the desired sURface finish of AT lEASt 120 MIcro-IncHes. DesirablY, the PEeniNg alSO dEnsIFies tHe coaTiNG.
AND while the present invEnTion waS deveLoped for use wiTh stoichioMETRic NiAl wHich IS bRIttle, it may be usEd advAntageouslY With any oTher cOating wiTh an unaccEPTably rouGh sUrfAce FinISH dUe to applicatiON TechNiQues and ThaT is inheRenTly BriTtlE, bUt which reQuires a sMoOtH sUrFacE finiSH for propEr PerFoRmaNce. TyPIcally, These CoatInGs HAve A higher aL cONTent ThAn OtheR, moRe DuctiLe coATinGs and arE identifiEd aS Beta PhAsEs, and thE coatings contAiN a substantIaL amOunt of THE beta phaSes or are primarily beta phASes.
An adVanTage oF the Present inVenTion is The ABility To tailOr the SuRfaCE RoughNESs Of a BrIttle, substANTiaLly stOiChioMetric NIAl coating. In this waY, The Inherent advanTagEs of A SUbStaNTiALly StOIchIOMetric NiAl compoSition can bE uTIlIzed, while tHE brItTle natuRe of the StoicHIometriC compositIon can be oVeRcomE SO thAt the surfaCe finish Of the artiCLe can BE mOdifiEd tO achieVe The Same rEsults CUrrEntly AchievAbLe with Non-stOiChiometrIc compositions that are eiTher loW in Ni Or lOw in Al.
AnoTheR AdvAntage of tHe prEsent invenTioN is The abIliTY to inCreaSE tHe dENsity Of thE Brittle coATiNg wITHoUt damaging iT. tHUs, tHe preSenT InventIon cAn modify the as-spraYEd coating to achIeve THE reQuiREd suRfAce finish and deSirEd DENsity in oRdEr to take advAntage of ThE ImproVed corRosion And oxidATIoN CapabiLitiEs oF the smootHer, DeNSer coatInG wIThout dAmagInG the brIttle cOAtinG. tHe airfoils that haVe had THEir suRFacE finiSh ModifieD In acCordance wiTh the presenT invenTion Have a More aerOdYnamic Gas FlOw path that SErves to
 adhesion of a ceramic TBC , while adense r c oat in g wi ll i mprove the cor r osio n and oxidation perfor mance  o f  the co ating  over t h eo p era ti on alli f ecycle  of  the pa rt. In ord erto  achieve the re quired sur fac e finish and  adesire dden s ity,the  coat ed art i cle is  worked b yo ne ora  combin a t io n of  controlled mecha n ic a l techniques t hat in cl u de i mpi ngi ng the sur fa ce of the art i cl e w ith particles ofpreselected siz e forapre s electe d tim ea ndintensity t o pr ovide a s moothe r  surfac e  finish  and h ope ful ly i m pr ov edde n sit y  o f t h e p arts wit ho ut  adve rsel y a f fect ing  the  brit tle coating m ate rial .  Wh ile t he me chan ic al te chniqu es ha ve  been used forothe r applica tio ns , t he y hav e  not b een  us ed to i mprovet hesu r f a ce  finish of stoichi om e t ri c NiAl c oating s  a pp l ied to t ur bin e ai r f oils.  Ino rd er to ap ply th e se  t echniqu es  to br it tle  st oichi o metr ic NiA l, certa in pr o cess controlsa re required t o  p r e ve n t da mag e to the co atin g . Th e pr e se nti nvent ion u ti l iz e s steel balls of pr es electe d siz e to peen the  surface o f t he airfo il t o  a c hieve the desi red s urface fin i sh of at  leas t 120 mi cro-inche s .  Desirab ly,  th e p een i n galso densifie s theco ating.And  whilethe  pr ese ntin vention w as devel op ed  f or  us e wit h  stoichi om etr ic  Ni Al wh i ch isbritt le,it  m a y b e useda dv a n tage ou sl y wi than y oth er c o ati ng with  an unacc ept a blyro ug h surfa ce finish due  t o applicat io n t echniq u e s and th at is inherently brittl e , but w hic h req uire s a smoot h s urface  fi n ish fo r prop er pe rf orm a n ce. T y p ic all y,  these coa t i ngs  have  a  hig her Alcontent than other ,  mo re ductile co ati ngsa n dare id e nti fi e d a s beta phases, an d the coat in g scontain as ubs ta ntial a mount o f the beta ph ases or a re primar il y be t a  ph ases.
An a dvantage  of the p r esent in venti onis the  a bil ity t o tail o r t he su rfacero ughnes s ofabrittle,  substantially stoichio metric  NiAl  co ating. In  th i s w ay, the i nher ent advant age s o f a s ubs t antia llys to ich i ometr ic N i Al compos i ti onc a nbe utilized , w hil e the  br i ttle n atur e of the stoichio m etric composit ionc a n b e o v erco me  so that the s urf ac e finish o fthe article  can bemo d ified  to ac hievethe sam e re s ults c urre ntl y achieva ble  w i th non- st oi c hiomet ricco mposit ions t h at a r e  either low in N i orl o w inA l.Anoth er  advant a ge o f the pres ent inventi on istheabili ty to i nc reasethe  d ensity oft he brittl e coa ting wi th outdam agingit.T h us, t he p re sen t inventi o n  c a nmo d ify  the  as-s pr ayed  coatingt o achiev e t h e requi re d s u r face f i ni s h  and desir eddensi t y  in ordert o ta k ea dvant age of  the i mproved cor ro sion an d o x i dation ca pabilitie s  of  t he s moother,  d ense rcoa ti ng without dama ging the  brittle c oating . T h e ai r foilsth at have hadtheir  s u rface f i n ish  modifi e d i n a cco rdan cewith the present invention ha ve a  more aer odyna mic g as  flow pa t h th at serve s  to
 adhesion_of a_ceramic TBC, while a_denser coating_will_improve the_corrosion_and oxidation performance_of the coating_over the operational life_cycle of the_part._In order to achieve the required surface finish and a desired density, the coated_article_is worked_by_one_or a combination of controlled_mechanical techniques that include impinging_the surface_of the article with particles of preselected size_for_a preselected time_and intensity to provide a smoother surface finish and_hopefully improved density of the parts_without adversely affecting_the_brittle_coating material. While the_mechanical techniques have been used for_other applications, they have not been_used to improve the surface finish of_stoichiometric NiAl coatings applied to turbine_airfoils. In order to apply_these techniques_to brittle stoichiometric NiAl, certain_process controls are_required to_prevent damage to_the coating. The present invention utilizes_steel balls of_preselected size to peen the surface_of_the airfoil to_achieve_the_desired surface_finish of at_least_120 micro-inches._Desirably,_the peening also densifies the coating.
And_while_the present invention was developed for use_with stoichiometric NiAl which_is_brittle, it may be_used advantageously with any other_coating with an unacceptably rough surface_finish due_to application_techniques and that is inherently brittle, but which requires a smooth_surface finish for proper performance. Typically,_these coatings have a_higher Al_content_than other, more_ductile_coatings and_are identified as beta phases, and the_coatings contain_a substantial amount of the beta_phases or are primarily_beta_phases.
An advantage of the present invention_is the ability to tailor the_surface roughness of a brittle,_substantially_stoichiometric_NiAl coating. In this way,_the inherent advantages of a substantially_stoichiometric NiAl composition_can be utilized, while the brittle nature_of_the stoichiometric composition can be overcome_so_that the surface finish of the_article_can_be modified to achieve the_same results currently achievable with non-stoichiometric_compositions that are either low in Ni or low_in Al.
Another advantage_of the present invention is_the_ability_to increase the density of the brittle coating without damaging_it. Thus,_the present invention_can modify the as-sprayed coating to achieve the required surface_finish and desired density in order to_take advantage of the improved corrosion and oxidation capabilities of the_smoother, denser coating without damaging the brittle coating._The airfoils that have had their surface_finish modified in accordance_with_the present invention have a more aerodynamic_gas_flow_path_that serves to