TY - THES

T1 - Development of micrometer-sized specimen production processes for nonconductive materials

AU - Milassin, Gabor

N1 - embargoed until null

PY - 2014

Y1 - 2014

N2 - The position resolved measurement of mechanical properties of materials allows a mapping of inhomogeneities and enables us to draw conclusions about the local composition, damage evolution and microstructure. The motivation for this work came from the prospect of gaining a better insight into the ageing mechanisms of fluorinated ethylene propylene (FEP) in low earth orbit (LEO) environment, which can lead to severe embrittlement of the polymer. FEP is widely used in form of foils for the outermost layer of the multi layer insulation (MLI) of spacecrafts. In this function, FEP is exposed directly to the LEO environment. The aim was to produce flat tensile specimens with a thickness of a few tens of micrometers, to be able to resolve a possible gradient in the mechanical properties within the 127 µm thick FEP outer layer of MLI, which was retrieved from the Hubble Space Telescope. Various types of micro machining methods were tested and assessed. The use of a microtome and an ion milling system proved to give the best results in respect to cheap and relatively fast specimen production. The well reproducible specimens were tested in tensile tests under an optical microscope and the results were then complemented by spectroscopic measurements.

AB - The position resolved measurement of mechanical properties of materials allows a mapping of inhomogeneities and enables us to draw conclusions about the local composition, damage evolution and microstructure. The motivation for this work came from the prospect of gaining a better insight into the ageing mechanisms of fluorinated ethylene propylene (FEP) in low earth orbit (LEO) environment, which can lead to severe embrittlement of the polymer. FEP is widely used in form of foils for the outermost layer of the multi layer insulation (MLI) of spacecrafts. In this function, FEP is exposed directly to the LEO environment. The aim was to produce flat tensile specimens with a thickness of a few tens of micrometers, to be able to resolve a possible gradient in the mechanical properties within the 127 µm thick FEP outer layer of MLI, which was retrieved from the Hubble Space Telescope. Various types of micro machining methods were tested and assessed. The use of a microtome and an ion milling system proved to give the best results in respect to cheap and relatively fast specimen production. The well reproducible specimens were tested in tensile tests under an optical microscope and the results were then complemented by spectroscopic measurements.

KW - tensile test

KW - local mechanical properties

KW - fluorinated ethylene propylene

KW - poly(tetrafluoroethylene-co-hexafluoropropylene)

KW - FEP

KW - ageing

KW - low earth orbit

KW - LEO

KW - Hubble Space Telescope

KW - HST

KW - multilayer insulation

KW - MLI

KW - microtome

KW - microtomy

KW - ion polishing

KW - ion milling

KW - Zugversuch

KW - lokale mechanische Eigenschaften

KW - Perfluorethylenpropylen-Copolymer

KW - FEP

KW - Alterung

KW - niedrige Erdumlaufbahn

KW - LEO

KW - Hubble Weltraumteleskop

KW - HST

KW - Multilagen-Isolation

KW - MLI

KW - Mikrotom

KW - Mikrotomie

KW - Ionenpolierer

M3 - Diploma Thesis

ER -