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Chemical vapor deposition of yttria-...

Varanasi, Venu Gopal.

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Chemical vapor deposition of yttria-stabilized zirconia as a thermal barrier coating for gas turbine engines.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Chemical vapor deposition of yttria-stabilized zirconia as a thermal barrier coating for gas turbine engines./
作者:	Varanasi, Venu Gopal.
面頁冊數:	255 p.
附註:	Source: Dissertation Abstracts International, Volume: 65-08, Section: B, page: 4160.
Contained By:	Dissertation Abstracts International65-08B.
標題:	Engineering, Chemical. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3144238
ISBN:	0496023144

Chemical vapor deposition of yttria-stabilized zirconia as a thermal barrier coating for gas turbine engines.
Varanasi, Venu Gopal.

Chemical vapor deposition of yttria-stabilized zirconia as a thermal barrier coating for gas turbine engines. - 255 p.

Source: Dissertation Abstracts International, Volume: 65-08, Section: B, page: 4160.

Thesis (Ph.D.)--University of Florida, 2004.

The gas turbine engine uses an yttria-stabilized zirconia (YSZ) coating to provide thermal insulation for its turbine blades. This YSZ coating must be tetragonal in crystal structure, columnar in microstructure, and be 100--250 mum thick to provide for adequate protection for the turbine blades in the severe engine environment. Currently, YSZ coatings are fabricated by electron-beam physical vapor deposition (EB-PVD), but this fabrication method is cost intensive. Chemical vapor deposition (CVD) is a more commercially viable processing method and a possible alternative to EB-PVD. The deposition of tetragonal YSZ from gaseous metal and oxidation sources were studied.

ISBN: 0496023144Subjects--Topical Terms:

1018531
Engineering, Chemical.

Chemical vapor deposition of yttria-stabilized zirconia as a thermal barrier coating for gas turbine engines.
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245 1 0 $a Chemical vapor deposition of yttria-stabilized zirconia as a thermal barrier coating for gas turbine engines.
300 $a 255 p.
500 $a Source: Dissertation Abstracts International, Volume: 65-08, Section: B, page: 4160.
500 $a Chair: Tim Anderson.
502 $a Thesis (Ph.D.)--University of Florida, 2004.
520 $a The gas turbine engine uses an yttria-stabilized zirconia (YSZ) coating to provide thermal insulation for its turbine blades. This YSZ coating must be tetragonal in crystal structure, columnar in microstructure, and be 100--250 mum thick to provide for adequate protection for the turbine blades in the severe engine environment. Currently, YSZ coatings are fabricated by electron-beam physical vapor deposition (EB-PVD), but this fabrication method is cost intensive. Chemical vapor deposition (CVD) is a more commercially viable processing method and a possible alternative to EB-PVD. The deposition of tetragonal YSZ from gaseous metal and oxidation sources were studied.
520 $a A chemical equilibrium analysis modeled the feasibility of depositing tetragonal YSZ for both chloride CVD (Zr-Y-C-O-Cl-H-Inert system) and metal-organic CVD (MOCVD) (Zr-Y-C-O-H system). Pure thermochemical properties and the assessed YSZ phase diagram were used in this analysis. Using the molar input of metals ((nY + nZr) and ( nY/(nY + nZr ) = 0.08)) as bases, equilibrium calculations showed that tetragonal YSZ formation was feasible. Tetragonal YSZ formation was feasible with high oxygen content (nO/(nY + nZr) > 8) and high temperature (T > 100°C) in the case of chloride CVD (Zr-Y-C-O-Cl-H-Inert). Tetragonal YSZ formation was feasible with high oxygen content (nO/( nY + nZr) > 5) and high temperature (T > 950°C) in the case of MOCVD (Zr-Y-C-O-H). Although solid carbon formation did not appear in chloride CVD, additional oxygen (nO/( nY + nZr) > 32) and low hydrogen content relative to carbon (nH/nC < 2) were required to avoid solid carbon formation in MOCVD.
520 $a Coatings were deposited using a set of base conditions derived from the chemical equilibrium analysis. In chloride CVD, YCl3 was not included because of its low vapor pressure, thus, ZrCl4 was oxidized with the H2-CO2 gas mixture. Monoclinic ZrO2 coatings were deposited at the thermochemically optimized conditions (n O/(nY + nZr) > 8, T > 1004°C) with approximately 5.5 mum h-1 growth rate.
520 $a In metal-organic CVD (MOCVD), liquid precursor solutions of Y- and Zr-beta-diketonate and Y- and Zr-n-butoxide precursors were used as the metal sources and O2 gas was used as the oxidation source. Using the Y- and Zr-beta-diketonate liquid precursor solution, tetragonal YSZ was deposited with a layered microstructure apparent and a maximum growth rate of approximately 14 mum h-1 (activation energy (E a) of 50.9 +/- 4.3 kJ mol-1). The growth rate (approximately 43 mum h-1 with Ea = 53.8 +/- 7.9 kJ mol-1) was improved using Y- and Zr- n-butoxide liquid precursor solutions, and the microstructure was columnar. Yet, two-phase deposition of monoclinic ZrO2 and tetragonal YSZ occurred. Results of electron-probe micro-analysis showed that the nY/(nY + nZr ) ratio was less than 45% of the nY/( nY + nZr) ratio in the liquid precursor solution.
590 $a School code: 0070.
650 4 $a Engineering, Chemical. $3 1018531
650 4 $a Remote Sensing. $3 1018559
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710 2 0 $a University of Florida. $3 718949
773 0 $t Dissertation Abstracts International $g 65-08B.
790 1 0 $a Anderson, Tim, $e advisor
790 $a 0070
791 $a Ph.D.
792 $a 2004
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3144238