In situ measurement and simulation of temperature and stress gradients during sintering of large ceramic components

Raether, F.; Klimera, Andreas; Baber, J.

doi:10.1016/j.ceramint.2006.10.025

Cited by 6 publications

(11 citation statements)

References 3 publications

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“…TOM was provided with loading stages that could transmit uniaxial forces between 0.1 and 180 N to the sample. Forces were applied by a motor that was placed inside the vacuum tight housing, but outside the thermal insulation of the furnace if special atmospheres had to be realized 1 . Punches with extensions on both sides with a V‐shaped cross section were used to obtain accurate measurements of their distance even if a small tilting of the setup occurred during the measurements 10 .…”

Section: Methodsmentioning

confidence: 99%

“…The partial pressure of evolved species can be increased using closed crucibles but this excludes many well‐established in situ measuring methods. It was demonstrated that graphite furnaces and gas fired kilns have atmospheres that strongly interact with the ceramics during sintering 1,11 . Although it requires some effort, these atmospheres have to be reproduced in the lab furnace to ensure transferability of results.…”

Section: Introductionmentioning

confidence: 99%

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Current State of In Situ Measuring Methods for the Control of Firing Processes

Raether

2009

Journal of the American Ceramic Society

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A combination of in situ measuring methods and computer simulation is suggested for the optimization of debinding and sintering processes in lab furnaces. From the optical measurement of sintering shrinkage and the mass loss measurement during debinding the respective reaction rates are derived. A high resolution of 1 lm and a reproducibility better than 0.3% were obtained for the optical measurement of sintering shrinkage. The atmospheres in the in situ measuring furnaces have to be closely matched to the production furnaces, to allow a transfer of the optimized heating cycles. A kinetic field method is used to obtain a model-free prediction of the debinding and sintering kinetics. Various other macroscopic in situ measuring methods are discussed, regarding their role during process optimization of ceramics. For example, heat transfer properties, required to calculate temperature and stress distributions during the heat treatment, were obtained by a modified laser-flash technique.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Current State of In Situ Measuring Methods for the Control of Firing Processes

Raether

2009

Journal of the American Ceramic Society

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“…In the sintering process, the local deformation behaviors of hardmetal products at specific temperatures is still not clear, which makes it difficult to control or reduce the sintering deformation of hardmetals. Raether et al [81] and Baber et al [82] reported a thermooptical measurement system for components or samples with a maximum size of ~ 40 mm, which is operated in a controlled atmosphere or vacuum. Dimensional changes are detected optically with a resolution of 0.3 µm and the maximum temperature can be up to 2400 °C.…”

Section: Bulk Densification Techniquesmentioning

confidence: 99%

Development of manufacturing technology on WC–Co hardmetals

Nie

Zhang

2019

Tungsten

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Hardmetals are tungsten carbide (WC)-based composites, which are made of WC as a hard phase and transition metals such as Co, Fe, or/and Ni as ductile binder matrices. Their properties can be mainly tailored through the grain sizes of the sintered carbides and the amount of metallic binder. As successful tool materials, hardmetals are widely applied in metal cutting, wear applications, chipless forming, stoneworking, wood, and plastic working. In 2017, about two-thirds of tungsten consumption (including recycled materials) were produced for hardmetals in the world. This paper briefly introduces the development of manufacturing technology on WC-Co hardmetals from three aspects: powder preparation, bulk densification, and performance characterization. Two special WC-Co hardmetals are also described: cobalt-enrichment zone (CEZ) hardmetals, and binderless hardmetals. Furthermore, the development prospects for manufacturing techniques of hardmetals are also presented in the end. Keywords Hardmetal • Ultrafine WC powder • Ultrafine cobalt powder • Extrusion press • Liquid sintering • Cobaltenrichment zone hardmetal • Binderless hardmetal 2 Powder preparation techniques Although WC-Co hardmetals can be made directly with mixing and reactive sintering of tungsten, carbon, and cobalt powders [6], the most commonly used method for preparing Tungsten www.springer.com/42864

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“…The authors of [9] showed that during heating at the surface of the treated material at the interface, a boundary layer (dynamic, related to the rate of gas flow around the material, heating, concentration) is formed. This layer, according to [10], forms the potentials of the elements exchanging with each other. For example, oxygen and carbon (in oxidation and decarburization), graphite (in graphite preparation), etc.…”

Section: Literature Review and Problem Statementmentioning

confidence: 99%

“…where y l =5n/U is the laminar sublayer thickness; From (10), it follows that the gradient of carbon concentrations in the gas phase at the metal surface and, therefore, the carbon flow are also determined by the gas phase temperature and structure of the boundary layers (dynamic, thermal).…”

Section: Considering Thatmentioning

confidence: 99%