Combustion synthesis and quasi-isostatic densification of powder cermets

Olevsky, Eugene A.; Strutt, E. R.; Meyers, Marc A.

doi:10.1016/s0924-0136(01)01236-5

Cited by 35 publications

(21 citation statements)

References 11 publications

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“…This rather low value as well as the large range is caused by the porosity of samples, making good hardness measurements a difficult task. The TiB 2 -xAl samples show an electrical conductivity (σ) ranging between 1.4 and 1.7 × 10 7 (Ω m) −1 , which is close to the calculated value for a fully dense sample of 2.3 × 10 7 (Ω m) −1 . This value is comparable to that of some WC-40Ag contact materials fabricated by sintering and metal infiltration.…”

supporting

confidence: 83%

“…In the QIP technique, the particulate acts as a pressuretransmitting medium (PTM) and redistributes an initially applied axial load to create a stress profile similar to isostatic pressing [3][4][5][6][7]. The pressure distribution in the PTM has been discussed in a previous paper [8].…”

Section: Introductionmentioning

confidence: 99%

“…However, one may take advantage of the ductile behavior when reaction products are still hot and apply techniques such as hot u Fax: +31-15-2843997, E-mail: richard.bouma@tno.nl pressing, hot rolling, hot isostatic pressing, or shock waves to eliminate porosity. Combustion synthesis followed by quasiisostatic pressing (QIP) in a granulate medium is the technique for removal of porosity studied here.In the QIP technique, the particulate acts as a pressuretransmitting medium (PTM) and redistributes an initially applied axial load to create a stress profile similar to isostatic pressing [3][4][5][6][7]. The pressure distribution in the PTM has been discussed in a previous paper [8].…”

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confidence: 99%

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Combustion synthesis of TiB2-based cermets: modeling and experimental results

Pacheco¹,

Bouma²,

Katgerman

2007

Appl. Phys. A

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TiB 2 -based cermets are prepared by combustion synthesis followed by a pressing stage in a granulate medium. Products obtained by combustion synthesis are characterized by a large remaining porosity (typically 50%). To produce dense cermets, a subsequent densification step is performed after the combustion process and when the reacted material is still hot. To design the process, numerical simulations are carried out and compared to experimental results. In addition, physical and electrical properties of the products related to electrical contact applications are evaluated. IntroductionSelf-propagating high-temperature synthesis (SHS), also known as combustion synthesis or solid-flame combustion, is considered a gasless combustion process. It is a cost-effective method for producing high-purity refractory compounds and advanced ceramics [1]. Here, the application to functionally graded cermets and electrical contact materials is shown.The basis of the reaction synthesis relies on the ability of gasless and highly exothermic reactions to be selfsustaining. Ignition can be achieved by a laser beam, ohmic heating, induction, or spark. However, a sufficient amount of energy needs to be deposited for the reaction to become selfpropagating. SHS has assumed significance for the production of intermetallics, ceramics, and cermets because it is a very rapid processing technique without the need for complex furnaces [2], and can increase the productivity in comparison with conventional techniques. One of the drawbacks of this technique is the high porosity of the final product (typically 50%), due to: (1) initial porosity in the reactant mixture, and (2) the higher density of the reaction products with respect to starting materials. A subsequent densification stage is needed, which is often hard to achieve in ceramic composite materials because they are highly deformation-resistant. However, one may take advantage of the ductile behavior when reaction products are still hot and apply techniques such as hot u Fax: +31-15-2843997, E-mail: richard.bouma@tno.nl pressing, hot rolling, hot isostatic pressing, or shock waves to eliminate porosity. Combustion synthesis followed by quasiisostatic pressing (QIP) in a granulate medium is the technique for removal of porosity studied here.In the QIP technique, the particulate acts as a pressuretransmitting medium (PTM) and redistributes an initially applied axial load to create a stress profile similar to isostatic pressing [3][4][5][6][7]. The pressure distribution in the PTM has been discussed in a previous paper [8]. In addition, the PTM thermally isolates the sample, thereby minimizing cracking due to rapid cooling and keeping the temperature of the specimen for a longer time above the ductile-to-brittle transition temperature of the ceramic phase. In this study, numerical simulations of the heat flow from the reacted material to its surroundings are presented and will be compared with experimental results in order to know whether a sufficient time-window exists for th...

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confidence: 83%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Combustion synthesis of TiB2-based cermets: modeling and experimental results

Pacheco¹,

Bouma²,

Katgerman

2007

Appl. Phys. A

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“…It is possible to apply isostatic pressure to the embedded compact by utilizing a granular powder as a pressure-transmitting medium. 21) Since the powder particles produced in the present study are granular (Fig. 2), the stress is also isostatic in the inner part of the compact except for near the surface.…”

Section: Densification Mechanism In the Sps Processmentioning

confidence: 77%

Densification and Structural Evolution in Spark Plasma Sintering Process of Mechanically Alloyed Nanocrystalline Fe-23Al-6C Powder

et al. 2003

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Nanocrystalline Fe-23 at%Al-6 at%C alloy powder was produced by mechanical alloying of the mixture of iron powder and aluminum powder (Fe-25 at%Al) with methanol, and was consolidated into fully dense compact by spark plasma sintering (SPS) at 1273 K. The compacts have nanocrystalline microstructure composed of mixture of -phase grains and -carbide (Fe 3 AlC) grains whose average grain size is about 50 nm. Although relatively large grains were also observed in places, their sizes were not over a few micrometers. The mechanisms of the densification and the structural evolution during the SPS process are discussed.

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“…[14][15][16] These studies concluded that the optimum initial relative density ranged between 60 and 75 pct for production of dense composites, with the maximum initial relative density for ignition at 83 pct for composites containing 42 to 63 wt pct Ni-Ti intermetallic. [17] TiC-Ni-Ti composites produced by sintering TiC with NiTi encountered substoichiometric carbide product formation during solidification leading to a nickel-rich intermetallic.…”

Section: Introductionmentioning

confidence: 99%

Production of Ni3Ti-TiC x intermetallic-ceramic composites employing combustion synthesis reactions

Burkes

Moore

Gottoli

et al. 2006

Metall Mater Trans A

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Combustion synthesis (CS) of nickel, titanium, and carbon (graphite) reactant particles can result in NiTi-TiC (stoichiometric) or Ni 3 Ti-TiC x (nonstoichiometric) composites. Since NiTi exhibits both superelasticity and shape memory properties while Ni 3 Ti does not, it is important to understand the SHS reaction conditions under which each of these composite systems may be synthesized. The stoichiometry of TiC x , for which 0.3 Յ x Յ 0.5, has an important controlling effect on the formation of either Ni 3 Ti or NiTi; i.e., formation of TiC 0.7 results in a depletion of titanium and formation of Ni 3 Ti. This deficiency should be considered when developing the SHS reaction. This article examines the SHS conditions under which Ni 3 Ti-TiC x composites are produced. Ignition, combustion, and microstructure characteristics of nickel, titanium, and carbon (graphite) particles were investigated as a function of initial relative density and thermophysical properties of the reactant mixture. Combination of the thermophysical properties and burning velocities controlled TiC x particle size, yielding a dependence of particle size on cooling rate. Theoretical calculations were performed and are in good agreement with the experimental data presented.

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Combustion synthesis and quasi-isostatic densification of powder cermets

Cited by 35 publications

References 11 publications

Combustion synthesis of TiB2-based cermets: modeling and experimental results

Combustion synthesis of TiB2-based cermets: modeling and experimental results

Densification and Structural Evolution in Spark Plasma Sintering Process of Mechanically Alloyed Nanocrystalline Fe-23Al-6C Powder

Production of Ni3Ti-TiC x intermetallic-ceramic composites employing combustion synthesis reactions

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