Impact of Al2O3 Particle Size on the Open Porosity of Ni/Al2O3 Composites Prepared by the Thermal Oxidation at Moderate Temperatures

Opálek, Andrej; Gaburjáková, Marta; Švec, P.; Kúdela, S.; Štĕpánek, Matej; Štefánik, Pavol; Iždinský, Karol

doi:10.3390/met11101582

Cited by 2 publications

(3 citation statements)

References 42 publications

(55 reference statements)

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“…The weight gain in all three oxidized CIP green tablets was caused by NiO growing, as was already showed in our previous work [21]. The formation of NiO layers on the surface of Ni particles was associated with the lowering of sample porosity.…”

Section: Kinetics Of Thermal Oxidation Of Cip-ed Powder Mixturesupporting

confidence: 80%

“…This composition was determined experimentally in our previous work because more than 12.87 wt. % Al 2 O 3 resulted in a substantially weaker sample cohesion after thermal oxidation [21]. Because the pressing of hard powders is accompanied by difficulties, Al powder with relatively plastic particles was used as a binder.…”

Section: Green Body Preparation From Ni + Al 2 O 3 + Al Powder Mixturementioning

confidence: 99%

“…The preparation of Ni-Al 2 O 3 composite preforms with high open porosity for infiltration and filtration purposes was demonstrated in our previous paper [21]. The method was based on the oxidation of loose powder mixtures of Ni and Al 2 O 3 with forming of oxide bonding on the powder interfaces.…”

Section: Introductionmentioning

confidence: 99%

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Ni Porous Preforms Compacted with Al2O3 Particles and Al Binding Agent

et al. 2023

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This work presents an energy-efficient, cheap, and rapid production method of a metal–ceramic preform with open porosity suitable for liquid metal infiltration and filtration applications. It is based on cold isostatic pressing of a mixture of relatively hard Ni and Al2O3 powders with the addition of small amount of Al powders, acting as a binding agent. Open porosity is primarily controlled by Al2O3 particles partially separating Ni particles from mutual contacts. Cold isostatic pressed green compacts were subjected to thermal oxidation by heating in air to 600 °C, 700 °C, and 800 °C. The weight gain and open porosity of oxidized compacts were examined. The chemical composition and microstructure were analyzed by SEM-EDS and XRD techniques. The stability of preforms and the effect of thermal cycling on the open porosity were tested by thermal cycling in an inert Ar atmosphere in the temperature range up to 800 °C. It appeared that, in addition to NiO being an expected product of oxidation, Ni aluminides and spinel particles also played an important role in inter-particle bonding formation. Ni-NiO porous composites resist chemical corrosion and exhibit structural and chemical stability at higher temperatures and admixed Al2O3 particles do not deteriorate them. After subsequent infiltration with Al, it can offer a lower density than other materials, which could result in lower energy consumption, which is highly needed in industries such as the automotive industry.

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Section: Kinetics Of Thermal Oxidation Of Cip-ed Powder Mixturesupporting

confidence: 80%

Section: Green Body Preparation From Ni + Al 2 O 3 + Al Powder Mixturementioning

confidence: 99%

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Ni Porous Preforms Compacted with Al2O3 Particles and Al Binding Agent

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Effect of ball milling time on the formation and thermal properties of Ag2Se and Cu2Se compounds

Tarani

Stathokostopoulos

Karfaridis

et al. 2023

J Therm Anal Calorim

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The thermoelectric materials community has made significant progress on nanostructured and processable materials to improve efficiency and flexibility, reducing manufacturing costs. Selenide compounds, such as Ag2Se and Cu2Se, have received a lot of attention because of their promising capabilities in thermoelectric applications. Additionally, Se is significantly more abundant than Te, with approximately ten times higher availability. High-energy ball milling (HEBM) process is a powerful solid-state synthesis/powder mechanical alloying method. The objective of this work is to form selenide compounds at different milling times (1–20 h) by HEBM process. The structural characterization of the compounds was studied by X-ray Diffraction and X-ray Photoelectron Spectroscopy, while the thermal stability of the prepared samples was examined by Thermogravimetric Analysis. The experimental results show that the Ag2Se sample synthesized at 20 h presents lower thermal stability because of the higher specific surface area and the increased porosity as a result of the hardening effect. Additionally, Cu2Se presents Cu2O(SeO3) as the main phase at low temperatures, while at higher temperatures, CuO is the dominant phase. Therefore, as the heating temperature increases, there is a complete evaporation of Se and a conversion of the remaining copper into copper oxide. The present study demonstrates a simple method for the synthesis of Ag2Se and Cu2Se thermoelectric materials with high oxidation resistance.

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Impact of Al2O3 Particle Size on the Open Porosity of Ni/Al2O3 Composites Prepared by the Thermal Oxidation at Moderate Temperatures

Cited by 2 publications

References 42 publications

Ni Porous Preforms Compacted with Al2O3 Particles and Al Binding Agent

Ni Porous Preforms Compacted with Al2O3 Particles and Al Binding Agent

Effect of ball milling time on the formation and thermal properties of Ag2Se and Cu2Se compounds

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