Warm pressing of cobalt base amorphous alloy powders

Esaki, Hiroki; Ameyama, Kei; Tokizane, Masaharu

doi:10.1179/026708389790222519

Cited by 3 publications

(5 citation statements)

References 2 publications

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“…There are two important points to be taken from this work, the ability to densify to high densities at very low temperatures under CSP, and that there is grain growth under the conditions the ZnO was processed under. The observed grain growth or coarsening process alone is important as it separates CSP from earlier stress‐assisted densification processes, such as warm pressing …”

Section: Introductionmentioning

confidence: 99%

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Demonstration of the cold sintering process study for the densification and grain growth of ZnO ceramics

et al. 2016

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With the cold sintering process (CSP), it was found that adding acetic acid to an aqueous solution dramatically changed both the densities and the grain microstructures of the ZnO ceramics. Bulk densities >90% theoretical were realized below 100°C, and the average conductivity of CSP samples at around 300°C was similar to samples conventionally sintered at 1400°C. Frequently, ZnO is also used as a model ceramic system for fundamental studies for sintering. By the same procedure as the grain growth of the conventional sintering, the kinetic grain growth exponent of the CSP samples was determined as N=3, and the calculated activated energy of grain growth was 43 kJ/mol, which is much lower than that reported using conventional sintering. The evidence for grain growth under the CSP is important as it indicates that there is a genuine sintering process being activated at these low temperatures and it is beyond a pressurized densification process.

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Section: Introductionmentioning

confidence: 99%

“…The observed grain growth or coarsening process alone is important as it separates CSP from earlier stress-assisted densification processes, such as warm pressing. [25][26][27][28][29][30]…”

Section: Introductionmentioning

confidence: 99%

Demonstration of the cold sintering process study for the densification and grain growth of ZnO ceramics

et al. 2016

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“…Here, we would like to point out the distinction between the cold sintering process and warm‐pressing even through both cases involve low‐temperature process with the assistance of external pressure. The warm‐pressing is often used to densify polymers, polymer‐derived ceramics, soft ceramics, glass/ceramic composites, and metallic particles . The primary driving force for the densification during warm‐pressing process is mechanical energy, which is different with sintering effect that is mainly driven by surface energy reduction.…”

Section: Introductionmentioning

confidence: 99%

“…The warm-pressing is often used to densify polymers, polymer-derived ceramics, soft ceramics, glass/ceramic composites, and metallic particles. [22][23][24][25][26][27] The primary driving force for the densification during warm-pressing process is mechanical energy, which is different with sintering effect that is mainly driven by surface energy reduction. Specifically, the competition between densification and coarsening should be considered in the case of sintering, whereas the coarsening is not an issue in warm-pressing process.…”

Section: Introductionmentioning

confidence: 99%

Cold sintering process for ZrO₂‐based ceramics: significantly enhanced densification evolution in yttria‐doped ZrO₂

Guo

Baker

et al. 2016

J Am Ceram Soc.

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We recently developed a novel technique of cold sintering process (CSP) to obtain dense ceramics at extraordinarily low temperatures. In this communication, we demonstrate the feasibility of applying CSP to zirconia‐based ceramics. As exemplified by 3Y‐TZP ceramics, a significantly enhanced densification evolution is observed. Water is simply utilized as a sintering aid to assist the ceramic densification under an applied external pressure. The low‐temperature advantage of CSP outstands in contrast to the densification curves compiled from other sintering techniques. A gradual monoclinic‐to‐tetragonal phase transformation is revealed in correspondence to the densification development, as well as contributes to the mechanical hardness evolution. A Vickers Hardness reaches ~10.5 GPa after annealing the cold‐sintered ceramics at 1100°C, which is comparable to those values reported in the previous studies at higher sintering temperatures. Such a sintering methodology is of significant importance as it provides a roadmap for cost‐effective processing of zirconia‐based ceramics and composites that enable broad practical applications.

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“…However, these processing methods are not always useful to produce a bulk nanocomposite with a full density. A number of studies have previously been carried out on the consolidation of amorphous alloy powders using various techniques: warm extrusion, 10,11) static high pressure compaction, [12][13][14][15][16] explosive compaction, 17,18) and dynamic compaction. 19,20) In order to synthesize an Fe-rich type nanocomposite magnet, dynamic compaction of amorphous Fe 77 Nd 15 B 8 powders has been tried and an amorphous bulk of 93% density could be obtained.…”

Section: Introductionmentioning

confidence: 99%

Consolidation of Fe-Co-Nd-Dy-B Glassy Powders by Spark-Plasma Sintering and Magnetic Properties of the Consolidated Alloys

et al. 2003

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glassy powders has been tried by spark-plasma sintering (SPS) at around the glass transition temperature in order to synthesize a hard magnetic bulk material with a nanocomposite structure. The glassy powders were consolidated into bulk forms with relative densities above 97% by the sintering at 788 K and over. The sample sintered for 420 s at 788 K had a nearly full density of 99.1% and still kept a glassy single phase. The increase in the sintering temperature and time caused crystallization and the formation of Fe 3 B phase. These as-sintered samples exhibited soft magnetic characteristics, but the soft magnetism changed to a hard type by annealing to form Nd 2 Fe 14 B, Fe 3 B and -Fe phases. The remanence, coercivity and maximum energy product for the bulk compact sintered for 420 s at 788 K, followed by annealing for 600 s at 913 K were 1.03 T, 277 kA/m and 83.1 kJ/m 3 , respectively.

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Warm pressing of cobalt base amorphous alloy powders

Cited by 3 publications

References 2 publications

Demonstration of the cold sintering process study for the densification and grain growth of ZnO ceramics

Demonstration of the cold sintering process study for the densification and grain growth of ZnO ceramics

Cold sintering process for ZrO₂‐based ceramics: significantly enhanced densification evolution in yttria‐doped ZrO₂

Consolidation of Fe-Co-Nd-Dy-B Glassy Powders by Spark-Plasma Sintering and Magnetic Properties of the Consolidated Alloys

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Warm pressing of cobalt base amorphous alloy powders

Cited by 3 publications

References 2 publications

Demonstration of the cold sintering process study for the densification and grain growth of ZnO ceramics

Demonstration of the cold sintering process study for the densification and grain growth of ZnO ceramics

Cold sintering process for ZrO2‐based ceramics: significantly enhanced densification evolution in yttria‐doped ZrO2

Consolidation of Fe-Co-Nd-Dy-B Glassy Powders by Spark-Plasma Sintering and Magnetic Properties of the Consolidated Alloys

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Cold sintering process for ZrO₂‐based ceramics: significantly enhanced densification evolution in yttria‐doped ZrO₂