Influence of Carbon Diffusion and the Presence of Oxygen on the Microstructure of Molybdenum Powders Densified by SPS

Moser, Mathias; Lorand, Sylvain; Bussiere, Florian; Demoisson, Frédéric; Couque, H.; Bernard, Frédéric

doi:10.3390/met10070948

Cited by 6 publications

(3 citation statements)

References 24 publications

(25 reference statements)

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“…At the same time, graphite is an active reductant and carbide former reacting with many materials (W, Mo, Ti, oxides) at elevated temperatures. [ 47–49 ] The reactivity of graphite is a crucia point when setting the FAST/SPS thermal cycle. Graphite has a low friction coefficient but also a low wear resistance.…”

Section: Tooling Materialsmentioning

confidence: 99%

Tooling in Spark Plasma Sintering Technology: Design, Optimization, and Application

Laptev,

Bram,

Garbiec

et al. 2024

Adv Eng Mater

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Spark plasma sintering as the prominent field‐assisted sintering technique (FAST/SPS) is a novel technology for the rapid, pressure‐assisted consolidation of powder materials. The main feature of FAST/SPS is the Joule heating of the used tooling. Tooling is a core part of the FAST/SPS setup, which must withstand high pressure at elevated temperatures ensuring a uniform temperature distribution inside the sintered part. This review looks at the standard FAST/SPS tooling, the specific tooling used for sintering complex‐shaped parts and for pressureless sintering. A particular focus lies on the graphite, the commonly used tooling material, and on alternative materials such as steel, alloys, ceramics, and composites. The review also considers the add‐on tooling elements, including spacers, foils, and thermal insulation. Furthermore, the paper discusses the basics of FAST/SPS modeling, the computer‐based optimization of FAST/SPS tooling, the simulation procedure used, and the modelling accuracy. The review briefly describes the tooling and equipment for manufacturing upsized parts and large‐scale production. In addition, the paper considers the tooling for FAST/SPS sintering under high pressure (up to 1 GPa) and ultra‐high pressure (over 1 GPa). The paper concludes with an analysis of the challenges and prospective solutions for the continued development of FAST/SPS tooling.This article is protected by copyright. All rights reserved.

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Section: Tooling Materialsmentioning

confidence: 99%

Tooling in Spark Plasma Sintering Technology: Design, Optimization, and Application

Laptev,

Bram,

Garbiec

et al. 2024

Adv Eng Mater

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“…In this sense, mastering and controlling the content of O in Mo will effectively improve strength and ductility [27][28][29][30][31][32][33]. Zhang et al [34] have adjusted the concentration of O solutes in Vanadium (V).…”

Section: Introductionmentioning

confidence: 99%

Exploring the Formation Mechanism, Evolution Law, and Precise Composition Control of Interstitial Oxygen in Body-Centered Cubic Mo

Xing

et al. 2022

Metals

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Interstitial oxygen (O) on the formation mechanism and enrichment distribution of body-centered cubic (BCC) molybdenum (Mo) has rarely been reported, and the O usually can cause serious brittle fracture in Mo. In this paper, we studied the formation mechanism and evolution of oxygen (O) when it was precisely controlled in the range of 3700–8600 parts per million (wppm). It was found that, with an increase in O concentration, O element not only existed in the form of solid solution but generated O element with different valence states in Mo metal. Large amounts of MoO2, MoO3, and Mo4O11 intermediate oxides were identified by electron probe micro-analyzer (EPMA) and X-ray photoelectron spectroscopy (XPS). Thermodynamic calculations revealed the formation process of oxides, and authenticity of the presence of O was verified by XPS. Enrichment and distribution of O element were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and EPMA. Moreover, the compressive yield strength and hardness of Mo were greatly affected by O content range of 4500–8600 wppm. Our study is helpful to understand the behavior of interstitial impurity O in refractory Mo metals and provides important guidance for development of high-purity rare Mo metals.

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“…On the other hand, microstructural heterogeneities could sometimes be observed between the core and the surface of the sample in the case of big parts, due to the important temperature gradients inside the sintering chamber [2]. Moreover, one of the major issues due to the use of graphite foils is the reaction between the carbon and the powder, leading to the formation of secondary and usually undesirable phases at the surface of the sintered sample and to carbon diffusion towards the bulk [14]. This phenomenon is particularly significant in the case of the sintering of metal powders, typically steels.…”

Section: Introductionmentioning

confidence: 99%

Development of Ti PVD Films to Limit the Carburization of Metal Powders during SPS Process

Ardigo-Besnard

Besnard

Moser

et al. 2021

Solids

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Spark plasma sintering technique is used for the fabrication of dense materials with a fine-grained microstructure. In this process, a powder is placed into a graphite mold and a uniaxial pressure is applied by two graphite punches. A graphite foil is inserted between the punches and the powder and between the mold and the powder to ensure good electrical, physical and thermal contact. One of the major drawbacks during sintering of metal powders is the carburization of the powder in contact with the graphite foils. In this study, a PVD coating of titanium was applied on the graphite foils in contact with the metal powder (pure iron). The results are promising, as the investigations show that the application of a Ti PVD film of 1.5 and 1.1 µm thickness is effective to completely avoid the carburization of iron powder. Carbon diffuses inside the PVD film during sintering. In parallel, iron diffusion was revealed inside the Ti coating of 1.5 µm thickness. On the other hand, a Ti PVD film of 0.5 µm thickness provides a protection against carbon diffusion just on the sides in contact with the mold, proving that the coating thickness represents an important parameter to consider.

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Influence of Carbon Diffusion and the Presence of Oxygen on the Microstructure of Molybdenum Powders Densified by SPS

Cited by 6 publications

References 24 publications

Tooling in Spark Plasma Sintering Technology: Design, Optimization, and Application

Tooling in Spark Plasma Sintering Technology: Design, Optimization, and Application

Exploring the Formation Mechanism, Evolution Law, and Precise Composition Control of Interstitial Oxygen in Body-Centered Cubic Mo

Development of Ti PVD Films to Limit the Carburization of Metal Powders during SPS Process

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