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Microscale characterization of metal...

Jain, Piyush.

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Microscale characterization of metallic coatings for a high strength high conductivity copper alloy.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Microscale characterization of metallic coatings for a high strength high conductivity copper alloy./
Author:	Jain, Piyush.
Description:	228 p.
Notes:	Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6695.
Contained By:	Dissertation Abstracts International67-11B.
Subject:	Engineering, Aerospace. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3243304
ISBN:	9780542987564

Microscale characterization of metallic coatings for a high strength high conductivity copper alloy.
Jain, Piyush.

Microscale characterization of metallic coatings for a high strength high conductivity copper alloy. - 228 p.

Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6695.

Thesis (Ph.D.)--The Johns Hopkins University, 2007.

NiCrAlY overlay coatings are being considered by NASA's Glenn Research Center to prevent blanching and reduce thermo-mechanical fatigue of rocket engine combustion chamber liners made of GRCop-84 (Cu-8%Cr-4%Nb) for reusable launch vehicles (RLVs). However, their successful application depends upon their integrity to the GRCop-84 during multiple firings of rocket engines. This study focuses on determining the adhesion of NiCrAlY coatings and their microstructural stability on GRCop-84 as a function of thermal cycling.

ISBN: 9780542987564Subjects--Topical Terms:

1018395
Engineering, Aerospace.

Microscale characterization of metallic coatings for a high strength high conductivity copper alloy.
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035 $a AAI3243304
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100 1 $a Jain, Piyush. $3 817522
245 1 0 $a Microscale characterization of metallic coatings for a high strength high conductivity copper alloy.
300 $a 228 p.
500 $a Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6695.
500 $a Adviser: Kevin J. Hemker.
502 $a Thesis (Ph.D.)--The Johns Hopkins University, 2007.
520 $a NiCrAlY overlay coatings are being considered by NASA's Glenn Research Center to prevent blanching and reduce thermo-mechanical fatigue of rocket engine combustion chamber liners made of GRCop-84 (Cu-8%Cr-4%Nb) for reusable launch vehicles (RLVs). However, their successful application depends upon their integrity to the GRCop-84 during multiple firings of rocket engines. This study focuses on determining the adhesion of NiCrAlY coatings and their microstructural stability on GRCop-84 as a function of thermal cycling.
520 $a Specimens were prepared by depositing NiCrAlY top coat on GRCop-84 by vacuum plasma spaying with a thin layer of Cu-26Cr as a bond coat. A thermal cycling rig was built to thermally cycle the NiCrAlY/Cu-26Cr/GRCop-84 specimens from RT to 600°C in an argon environment, with 10 minutes hold at 600°C, and 4 minutes hold at RT. Samples were cut from the coupons in as-received condition (AR), after 100 thermal cycles (TC-100), and after 300 thermal cycles (TC-300) for characterization. A newly developed interfacial microsample testing technique was employed to determine the adhesion of the coatings on GRCop-84, where bowtie shaped microsamples having interfaces normal to the tensile axis were tested.
520 $a Interfacial microsamples of NiCrAlY/Cu-26Cr/GRCop-84 in all the conditions (AR, TC-100, and TC-300) failed cohesively in the substrate at a UTS of 380+/-5 MPa and their interfaces remained intact. The microstructural characterization revealed that microstructure of the NiCrAlY/Cu-26Cr/GRCop-84 specimens does not degrade as a function of thermal cycling. Constitutive properties of NiCrAlY, Cu-26Cr, and GRCop-84 were measured by testing monolithic samples and were used to build the finite element model (FEM) of the interfacial microsamples. The FE model analyzed the local stress-strain in the interfacial microsamples during the testing and confirmed the strength of the interfaces to be higher than 380+/-5 MPa.
520 $a Depleted zones, devoid of Cr2Nb particles, were observed in the substrate near the interface, which has been attributed to uncontrolled processing parameters during the coating deposition. The interfacial microsamples containing depleted zones, failed at 335+/-25 MPa in AR condition exhibiting cohesive-adhesive failure, and at 360+/-15 MPa in TC-300 condition exhibiting adhesive failure. All these results suggested that the presence of depleted zone decreases the adhesion of the coating and should be avoided in future coatings deposition.
520 $a Adhesion of two top coats, NiCrAlY (with the Cu-26Cr bond coat) and the Cu-26Cr (without any bond coat), were found to be lower on the grit blasted GRCop-84 than on the polished GRCop-84. The adhesion of both the top coats on polished GRCop-84 was measured to be 380+/-5 MPa with cohesive failure in the substrate, while the adhesion of NiCrAlY top coat on the grit blasted GRCop-84 was measured to be 142+/-35 MPa with cohesive failure in the Cu-26Cr bond coat, and the adhesion of Cu-26Cr top coat on the grit blasted GRCop-84 was measured to be 360+/-25 MPa with cohesive failure in the Cu-26Cr top coat. The microstructural characterization revealed that the reason of lower strength of top coats on the grit blasted GRCop-84 was the porosity present in the coatings on the grit blasted GRCop-84, while the coatings on the polished GRCop-84 did not have any measurable porosity.
590 $a School code: 0098.
650 4 $a Engineering, Aerospace. $3 1018395
650 4 $a Engineering, Mechanical. $3 783786
650 4 $a Engineering, Materials Science. $3 1017759
690 $a 0538
690 $a 0548
690 $a 0794
710 2 0 $a The Johns Hopkins University. $3 1017431
773 0 $t Dissertation Abstracts International $g 67-11B.
790 1 0 $a Hemker, Kevin J., $e advisor
790 $a 0098
791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3243304