Journal Article

FZJ-2020-04441

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Hot‐pressing platelet alumina to transparency

Schlup, A. P. (Corresponding author) ; Costakis, W. J. ; Rheinheimer, W.FZJ* ; Trice, R. W. ; Youngblood, J. P.

2020
Soc. Westerville, Ohio

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Please use a persistent id in citations: http://hdl.handle.net/2128/26468  doi:10.1111/jace.16932

Abstract: Alumina powder with a platelet morphology was hot‐pressed to transparency with preload pressures of 0‐8 MPa, maximum temperatures of 1750‐1825°C, maximum pressures of 2.5‐80 MPa, and isothermal hold times of 1‐7 hours. Optical transmission (in‐line and total), as well as optical losses (backward/forward scattering and absorption), of the hot‐pressed samples were measured and related to the microstructure. Higher hot‐pressing temperatures increase the in‐line transmission. A gray discoloration of the samples (indicative of high absorption) was minimized by heat treating the powder in air prior to hot pressing and reducing the preload pressure. Maximum pressures above/below 10 MPa increased porosity, which decreased in‐line transmission and increased backward/forward scattering. Lower densities at higher pressures are attributed to a pore‐swelling phenomenon. Increasing isothermal hold time decreased porosity, which increased in‐line transmission and reduced backward/forward scattering. Best optical properties with an in‐line transmission of 65.3% at 645 nm (0.8 mm thick) were achieved by hot‐pressing heat‐treated platelet alumina powder with a preload pressure of 0 MPa, maximum temperature of 1800°C, maximum pressure of 10 MPa, and an isothermal hold time of 7 hours. This high in‐line transmission, despite its large grain size (65 µm), is attributed to crystallographic orientation of the platelets during hot pressing.

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Contributing Institute(s):

1. Werkstoffsynthese und Herstellungsverfahren (IEK-1)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

Appears in the scientific report 2020

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Database coverage:
; ; Clarivate Analytics Master Journal List ; Current Contents - Engineering, Computing and Technology ; Current Contents - Physical, Chemical and Earth Sciences ; DEAL Wiley ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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