report of thermal barrier coating of gas turbine blades

8/13/2019 Report of THERMAL BARRIER COATING OF GAS TURBINE BLADES

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A

SEMINAR REPORT

ON

THERMAL BARRIER COATING OF

GAS TURBINE BLADES

SUBMITTED BY

Ashutosh kumar tiwari

Roll o!"#$#%$#%&

IIIr' B!T()h M!E

SUBMITTED TO

Mr!*i+(k ,asari

Mr! -!S B(hl


2/21

INDE.

Cot(ts ,a/(! No!

0! INTRODUCTION 0

%! HISTORIACL BAC1GROUND 2

2! DIFFERENT LAYERS &

&! CREATION OF TBC $

3! FAILURE OF TBC 4

5! MATHEMATICAL BAC1GROUND 00

$! ,RO,OSED RESEARCH 02

6! CONCLUSION 0$

4! REFERENCES 06


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Providing o%idation protection to the sustrate' the meta!!ic ond coat !a"er

provides an ade4uate!" prepared surface to #hich the ceramic !a"er adheres$ The

ceramic !a"er composition is se!ected ased on therma! conductivit"' high3temperature

stai!it"' and therma! e%pansion compatii!it" #ith the sustrate$ Due to its !o# therma!

conductivit" and good thermo c"c!ic durai!it" #hen stai!i9ed against phase

transformation' 9irconia has ecome the ceramic of choice$ The current i!a"er design

and composition of TB& have evo!ved from a mu!titude of designs and a numer of

compositions tested over a period of severa! decades$

Fi/ 0! Mi)ro/ra7hs o8 La%9r%O$a' YS9 )oati/

Som( o8 7ro'u)ts i)or7orati/ TBC:"

Turine !ades

&utting too! inserts

Aero engine parts

1as turine parts such as comustion !iners' shroud' no99!es or !ades

I& engine parts

Roc2et no99!es and va!ve odies

Damper pin for turine uc2et

Th(rmal


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/:0

%! HISTORICAL BAC1GROUND

Pratt ;


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2! DIFFERENT LAYERS

In an effort to protect the turine !ades from e%treme!" high temperature gasesF the

therma! arrier coating /TB&0 s"stem has een imp!emented$ The TB& s"stem

primari!" consists of fo!!o#ing !a"ers.

(0 &eramic top3coat'

:0 Therma!!" gro#n o%ide /T1O0',0 Bond coat' and

C(rami) to7")oat. 3 The ceramic top3coat is the !a"er that provides therma! insu!ation

for the !ade$ It has a ver" !o# therma! conductivit" and has een designed using point

defects to #ithstand therma! c"c!es$ This !a"er is t"pica!!" made of :O, #hich is

stai!i9ed #ith rO:or in short S$ The therma! conductivit" for this !a"er at a

temperature of a thousand degrees &e!sius is :$,


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/)0

Fi/ur( 2! A s)h(mati) illustratio o8 a mo'(r th(rmal ;arri(r )oati/ s a th(rmall< /row o=i'( ?TGO@ a' a alumium

ri)h ;o' )oat! Th( t(m7(ratur( /ra'i(t 'uri/ (/i( o7(ratio is o+(rlai'!

Temperature


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&! CRAEATION OF TBC

The ond coat is primari!" deposited " He!ectrop!ating in con-unction #ith diffusion3

a!umini9ing or chemica!3vapour deposition$ Recent!"' the high ve!ocit" o%"3fue!

techno!og" /5COG0 is a!so increasing!" used for this tas2$

Fi/!&" a@A,S> Lamiar

stru)tur(

;@EB",*D )olumar stru)tur(


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The &eramic top3coat on other hand is current!" eing deposited in t#o different #a"s.

(0 Air p!asma3 spra"ed /APS0 deposition and

:0 E!ectron3eam ph"sica!3vapour deposition /EB3PCD0$

A picture of the different

microstructures created " each method are sho#n in Gigure +$

Air 7lasma" s7ra


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El()tro";(am 7h


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#as decreased' crac2ing of the ond coat in EB3PCD coated s"stems #as suppressed'

the !ife of the coated s"stem increased significant!" and de!amination of the top3coat

#as oserved$ A suse4uent GE ana!"sis sho#ed that' " su-ecting the s"stem to the

higher mechanica! strain' significant tensi!e stresses deve!op in the T1O and the ond

coat that are thought to e responsi!e for the oserved crac2 initiation and

propagation$ The GE mode! a!so predicts that crac2ing initiates at specific geometric

features of the rough interface of a PS coated s"stem' #hich #as confirmed "

meta!!ographic e%amination of fai!ed samp!es$ The decrease of the app!ied mechanica!

strain and hence of the deve!oped stresses !ed to the suppression of fai!ure " ond coat

crac2ing and activate de!amination$ These resu!ts out!ine the importance of designing

TMG tests and se!ecting the appropriate mechanica! !oading in order to acce!erate

testing and sti!! trigger the same fai!ure mechanisms as oserved in3service$

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O=i'atio"I'u)(' Failur( o8 Th(rmal Barri(r Coati/s:"

On pro!onged high3temperature e%posure in air' therma! arrier coatings /TB&s0 on

ond3coated super a!!o"s fai! " spa!!ing$ It is a ne# discovered TB& fai!ure mode' in

#hich fai!ure is associated #ith moisture3enhanced su3critica! crac23gro#th a!ong the

ond3coat therma!!" gro#n o%ide interface$ B" ma2ing concurrent pie9ospectroscop"

measurements' the interfacia! fracture energ" #as determined to e K (* =m/e%p :0 3 a

considera!" sma!!er va!ue than that of sapphiremeta! interfaces prepared in the

!aorator" ut consistent #ith measurements of the effects of segregation onmeta!ceramic interfaces$ Ne# insights into the mechanism under!"ing fai!ure of the

therma!!" gro#n o%ide have come from direct optica! microscop"$ These indicate that

fai!ure is associated #ith surface roughness of the ond3coat and specifica!!" that the

therma!!"3gro#n o%ide separates from the ond3coat on coo!ing at the concave /LcrestsL0

surface features$ These !oca!!" separated regions gro# #ith o%idation time and are seen

to !in23up$ These events are e!ieved to e the precursor events that gro# to provide the

critica!3si9ed f!a#s from #hich uc2!ing and spa!!ing of therma! arrier coatings occur$

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5! MATHEMATICAL BAC1GROUND

Because of the comp!e%it" of this mode!' the ma-orit" of the resu!ts are done

through e%perimentation$ In order to get a ph"sica! fee! for #hat is happening' #e have

made severa! assumptions in our ana!"sis.

(0 Tgas J T( J (>7, degrees e!vin #hich is 2ept constant$

:0 T+ J Tair J :?> degrees e!vin #hich is 2ept constant$

,0 Assume that a sma!! portion of the air foi! that I represent as a rectang!e is a

good mode! of the entire air foi!$

+0 Properties of state sta" constant throughout the mode! ecause oundar"

conditions sta" constant$

)0 No heat f!u% through the top and ottom of our mode! /insu!ated0$

60 T1O !a"er has no effect on temperature distriution

This information comined #ith ta!e ( #as inputted into &OMSO and so!ved$ The

resu!ts are sho#n in figure 6$

Ta;l( 0: Mat(rial 7ro7(rti(s 8or a tur;i( ;la'(

Ni Sustrate Ni&o&rA! SR

Densit" /2gm,0 >>>* 7,:* 6*,7

Therma!

conductive/( 6)6

/((0


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Fi/ur( $: %"D Dia/ram o8 th( ;la'(

Fi/ur( 6: Comsol mo'(l o8 th( t(m7(ratur( 'istri;utio i a tur;i( ;la'(

As one can see in Gigure 6' the temperature distriution drops dramatica!!" through the

ceramic top coat ecause of its ver" !o# therma! conductivit"$ Gurthermore' these

resu!ts sho# that the temperature distriution through the supper a!!o" is #e!! e!o# the

me!ting point of the meta! #hich is #hat #as e%pected$

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$! ,RO,OSED RESEARCH

The on!" #a" to improve efficienc" in a gas turine engine is to increase the

temperatures #ithin the s"stem$ Because of this more research needs to e done in

improving re!ia!" and therma! conductive!" of the therma! arrier coat$ Gocus needs to

e p!aced on the current fau!ts of TB& s"stem and ho# the" can e reso!ved$ Some

pro!ems are #ith o%idation of the materia!' and !ac2 of mode!!ing to predict the !ife

span of the therma! arrier coating$ In addition' ne# research in different #a"s of

coo!ing the !ade needs to e done$ A reasona!e area to focus on #ou!d e #ater

coo!ing and nitrogen coo!ing$


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Mo'(lli/:3 Mode!!ing constitutes a second main research area$ The principa! goa! in

the mode!!ing of the p!asma spra"ing process is the improvement of our understanding

aout the re!ation et#een the process parameters and the structure and effectiveness of

the coating s"stems$ Mode!!ing "ie!ds asic information' #hich can !ead to the

optimi9ation of the process$ A simi!ar function corresponds to the mode!!ing of therma!

arrier coating !ife$ The achieved deve!opment of a !ifetime mode! ased on the

microstructure gives important indications for an optimi9ed !a"er s"stem$

Th(rmal )


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temperatures in an o%idi9ing atmosphere$ An ear!" e%amp!e of such a s"stem is a!umina

fiers in an a!umina matri%$ To rea!i9e the u!timate !oad carr"ing capai!ities at high

temperatures' sing!e cr"sta! o%ide fiers ma" e used' giving the possii!it" to operate

under temperatures of (+**&$ 5igher operating temperatures for gas turine engines

are continuous!" sought in order to increase their efficienc"$ 5o#ever' as operating

temperatures increase' the high temperature durai!it" of the components of the engine

must corresponding!" increase$ Significant advances in high temperature capai!ities

have een achieved through formu!ation of iron' nic2e! and coa!t3ase super a!!o"s$


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6! CONCLUSION

1as turines engine constitute a #ide and good option for po#er generation

used for oth' industria! and aeronautica! app!ications$ This techno!og" is re4uesting for

etter and more re!ia!e materia!s to use most!" in those areas in #hich temperatures

are e%treme!" highF !i2e' fist ro# of turines !ade and comustion chamer$ B!ades

materia!s for turine area in gas turines have advanced rapid!" in the !ast : decades$

These !ades are constructed using specia! a!!o"s and are covered " specia! coats$

Modifications are intended to increase the a!!o#ed temperature up to ()**O& #ithout

coo!ing$ To increase efficienc"$

&eramic coating is app!ied to the surface of the turine !ade using severa!

methods$ The most important ones are. E!ectron Beam Ph"sica! Capor Deposition /EB3

PCD0 and Arc P!asma Spra"a!e /APS0 po#der method$ Besides the techno!og" aimed

to produce etter coats' materia!s science is current!" #or2ing e%tensi!e in &eramic

Matri% &omposites' formed asica!!" " si!icon caride fiers and specia! farics in

order to increase the temperature gap in !ocations specia!!" sensi!e for gas turine

operation$

The !ast and' at the same time' !argest area dea!s #ith the deve!opment of ne#

therma! arrier coatings$ In this #ide activit"' o%idic materia!s are principa!!" eing

studied as candidates for therma! arrier coatings and' #here app!ica!e' deve!oped to

ne# TB&3s"stems$ The e%perience and 2no#3ho# in the other research areas

/processing' characteri9ation' mode!!ing0 are eing intense!" used for the further

deve!opment of ne# s"stems$

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0#! REFERENCES


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(0 &!ar2e' D$ R$ and evi' &$ 1$ /:**,0$ HMateria!s Design for the Ne%t 1eneration

Therma! Barrier &oatings$ Annua! Revie#s of Materia!s Research. Co!$ ,,' pp$ ,>,3

+(7$

:0 Nitin P$ Padture' Maurice 1e!!' Eric 5$ =ordan$ LTherma! Barrier &oatings for 1as3

Turine Engine App!ications$L Science (: Apri! :**:. Co!$ :?6$ no$ ))66' pp$ :>* 3

:>+

,0 ODonoghue isa$ L,3+(7$ August :**,

>0 $A$ hor' $


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report of thermal barrier coating of gas turbine blades

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