Capillary forces between spheres during agglomeration and liquid phase sintering

Hwang, K. S.; German, Randall M.; Lenel, F. V.

doi:10.1007/bf02646216

Cited by 70 publications

(26 citation statements)

References 12 publications

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“…A low-contact angle induces liquid spreading over the solid grains, providing a capillary attraction that helps densify the system. For small grains, contact stress can rival that seen in pressure-assisted sintering techniques, such as hot isostatic pressing [31]. In practice, a broad range of capillary conditions exist, since the microstructure is composed of a range of grain sizes, grain shapes, pore sizes, and pore shapes, each with a different capillary condition.…”

Section: Contact Angle and Dihedral Anglementioning

confidence: 99%

“…Thus, depending on the contact angle, liquid formation causes either densification or swelling. The magnitude of the capillary effect depends on the amount of liquid, particle size, and contact angle [31].…”

Section: Contact Angle and Dihedral Anglementioning

confidence: 99%

“…33. For two spheres, the pressure difference DP across the curved liquid surface with radii of curvature of r and X/2 is [31,110],…”

Section: Incipient Liquid Formationmentioning

confidence: 99%

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Review: liquid phase sintering

2009

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Liquid phase sintering (LPS) is a process for forming high performance, multiple-phase components from powders. It involves sintering under conditions where solid grains coexist with a wetting liquid. Many variants of LPS are applied to a wide range of engineering materials. Example applications for this technology are found in automobile engine connecting rods and high-speed metal cutting inserts. Scientific advances in understanding LPS began in the 1950s. The resulting quantitative process models are now embedded in computer simulations to enable predictions of the sintered component dimensions, microstructure, and properties. However, there are remaining areas in need of research attention. This LPS review, based on over 2,500 publications, outlines what happens when mixed powders are heated to the LPS temperature, with a focus on the densification and microstructure evolution events.

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Section: Contact Angle and Dihedral Anglementioning

confidence: 99%

Section: Contact Angle and Dihedral Anglementioning

confidence: 99%

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Review: liquid phase sintering

2009

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“…This phenomenon is difficult to be measured, so a theoretical approach is used more often, taking into consideration among others particle size, contact angle, distance between particles and liquid volume [22][23][24]. A significant fraction of pores can be filled by the liquid film within a very short time due to the capillary forces for systems with wettable liquids.…”

Section: Capillary Forcesmentioning

confidence: 99%

“…A significant fraction of pores can be filled by the liquid film within a very short time due to the capillary forces for systems with wettable liquids. However, at large contact angles and intermediate particle separation, capillary forces equal to zero should be expected [22]. Actually, the distribution of ceramic grains in the powder or pellet exposed to sintering is entirely random, and ceramic powders are characterized by typically monomodal grain size distribution.…”

Section: Capillary Forcesmentioning

confidence: 99%

Vaporization and Poor Wettability as the Main Challenges in Fabrication of TiB2-Cu Cermets Studied by SPS

Ziemnicka-Sylwester

2014

Metals

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TiB2-Cu cermets with various volume fractions of copper (from 3 to 30 vol. %) were produced via liquid phase sintering at the temperature range 1100-1200 °C in vacuum using spark plasma sintering (SPS) technique. Full densification could not be achieved as the consequence of poor wettability and vaporizing Cu. The quantitative Rietveld analysis indicated that insignificant reduction in Cu content occurred only in sample with initially 3 vol. % of Cu, but then densification was negligible. The relative density improved along with increasing volume content of Cu (10-20 vol. %), but then predominant amount of Cu introduced was reduced as the effect of vaporization or swelling, which caused that pellet with intended 20 or 30 vol. % of Cu contained respectively only 6 or 17 vol. % after sintering. Moreover, Cu droplets were released from the die at the temperature of 1000-1030 °C near the Cu melting point. The effect of vaporization was successfully reduced by increased heating rate and when isothermal annealing process was skipped, however, it could not be entirely eliminated. The experimental results on Cu vaporization are confronted with parameters that are commonly considered in the production of cermets, such as oxidation, wettability, contact angle and viscosity as well as their impact on densification.

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Powder Metallurgy and Sintered Materials

Kaysser¹,

Weise

2000

Ullmann's Encyclopedia of Industrial Chemistry

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The article contains sections titled: 1. Introduction 1.1. Production Routes 1.2. Product Groups 1.3. History and Developments 1.4. Economic Aspects 2. Powder Production 2.1. Mechanical Methods 2.1.1. Mechanical Disintegration of Melts 2.1.2. Mechanical Disintegration of Solids 2.2. Physicochemical Methods 2.3. Chemical Methods 3. Powder Properties and Characterization 4. Powder Conditioning 5. Pressing and Forming at Ambient Temperatures 5.1. Uniaxial Pressing 5.2. Isostatic Pressing, Cold Rolling, and Extrusion 5.3. Pouring, Preforming, and Injection Molding 6. Sintering 6.1. The Sintering Process 6.1.1. Solid‐State Sintering 6.1.2. Liquid‐Phase Sintering 6.2. Sintering Furnaces and Atmospheres 7. Pressing and Shaping at Elevated Temperature 7.1. Hot Pressing and Hot Isostatic Pressing 7.2. Sinter Forging and other Methods 8. Structural Parts 8.1. Structural Ferrous Parts 8.1.1. Low‐Alloyed Steels 8.1.2. High‐Alloyed Steels 8.1.3. Secondary Operations 8.2. Copper and Copper Alloys 8.3. Aluminum and Aluminum Alloys 9. High‐Performance Materials 9.1. High‐Melting Metals and Alloys 9.2. Light Alloys 9.2.1. High‐Performance Aluminum Alloys 9.2.2. Titanium and Titanium Alloys 9.2.3. Magnesium and Beryllium 9.3. High‐Temperature Nickel and Cobalt Superalloys 9.4. Magnetic Materials 9.5. Hardmetals and Cermets 9.6. Metal ‐ Ceramic Composites 9.7. Electric Contact Materials 9.7.1. Contact Materials for Low‐Voltage Switchgear 9.7.2. Contact Materials for High‐Voltage Switchgear 10. Parts with Inherent, Functional Porosity

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Capillary forces between spheres during agglomeration and liquid phase sintering

Cited by 70 publications

References 12 publications

Review: liquid phase sintering

Review: liquid phase sintering

Vaporization and Poor Wettability as the Main Challenges in Fabrication of TiB2-Cu Cermets Studied by SPS

Powder Metallurgy and Sintered Materials

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