Unusual Crack Formation on an Autoclave during Thermal Cracking Experiments on Anthropogenic Resources
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A. Schmid
Abstract
Thermal cracking experiments were performed on anthropogenic resources (post consumer plastics with PVC impurities) in an autoclave under N2 atmosphere and at 500 °C. After about 48 h, a crack near the flange resulted in pressure loss. Deposits of FeCl2 · 2H2O, NiCl2 · 2H2O and Ni2O2OH could be evidenced on the cracks using XRF and XRD. In the crack itself, mainly Cr2O3 could be found at the crack initiation site, while chlorides of Fe, Cr, and Ni could be observed at the tip of the crack using EDS. Metallographic examinations using V2A and Beraha etchants revealed that the crack propagated transgranularly. The basic structure exhibits not only dendritic segregations (cast structure) but also segregation bands (deformed microstructure). In addition to that, Ti(C,N) precipitations could be found. TiN (yellow) mainly occurred in the core, while TiC (white) was primarily found at the edge of the sample.
Kurzfassung
Versuche zum thermischen Cracken anthropogener Ressourcen (alte Kunststoffe mit PVC-Anteilen) wurden in einem Autoklav bei 500 °C unter N2-Atmosphäre durchgeführt. Nach etwa 48 h führte ein Riss nahe dem Flansch zu einem Druckverlust. Über dem Riss wurden Ablagerungen von FeCl2 · 2H2O, NiCl2 ·2H2O und Ni2O2OH mittels RFA und XRD nachgewiesen. Im Riss selbst, wurden mittels EDX hauptsächlich Cr2O3 am Rissanfang nachgewiesen und Chloride von Fe, Cr und Ni am Rissende. Der Riss verlief transkristallin durch das Gefüge. Dies konnte metallographisch im LOM gezeigt werden, wobei die Ä;tzungen mit V2A und Beraha 2 durchgeführt wurden. Das Grundgefüge zeigt, dass neben dendritischen Seigerungen (Gussgefüge) auch zeilige Seigerungen (verformtes Gefüge) vorliegen. Des Weiteren wurden Ti(C,N) Ausscheidungen festgestellt, wobei im Kern vorwiegend TiN (gelb) und am Rand TiC (weiß) vorliegt.
References / Literatur
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© 2018, Carl Hanser Verlag, München
Articles in the same Issue
- Contents/Inhalt
- Contents
- Editorial
- Editorial
- Technical Contributions/Fachbeiträge
- Modern Methods for the Microscopic Characterization of ZnO Varistor Grain Boundaries
- Microstructural Characterization of Ultra-High Strength Martensitic Steels
- Optimized Segmentation of the 3D Microstructure in Cast Al-Si Piston Alloys
- Unusual Crack Formation on an Autoclave during Thermal Cracking Experiments on Anthropogenic Resources
- Meeting Diary/Veranstaltungskalender
- Meeting Diary
Articles in the same Issue
- Contents/Inhalt
- Contents
- Editorial
- Editorial
- Technical Contributions/Fachbeiträge
- Modern Methods for the Microscopic Characterization of ZnO Varistor Grain Boundaries
- Microstructural Characterization of Ultra-High Strength Martensitic Steels
- Optimized Segmentation of the 3D Microstructure in Cast Al-Si Piston Alloys
- Unusual Crack Formation on an Autoclave during Thermal Cracking Experiments on Anthropogenic Resources
- Meeting Diary/Veranstaltungskalender
- Meeting Diary
