Electrostatic Adsorption of a Colloidal Sintering Agent on Silicon Nitride Particles

Lidén, Eva; Persson, Michael; Carlström, Elis; Carlsson, Roger

doi:10.1111/j.1151-2916.1991.tb04108.x

Cited by 56 publications

(20 citation statements)

References 6 publications

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“…The as‐received Si 3 N 4 powders in water alone show an isoelectric point (IEP) of ~5 pH, and the largest magnitude potentials are observed at ~2.5 pH and ~9 pH, of 30 and −25 mV, respectively. This matches with similar research finding an IEP of silicon nitride from 4 to 7 pH . The IEP of Si 3 N 4 can vary greatly based on the ratio of basic amine to acidic silanol groups present in the surface, the amounts of each varied by pretreatments of starting powders .…”

Section: Resultssupporting

confidence: 91%

Stabilizing Highly Loaded Silicon Nitride Aqueous Suspensions Using Comb Polymer Concrete Superplasticizers

2016

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The stabilization of highly loaded silicon nitride suspensions will afford the processing of complex and near‐net shaped parts using methods such as injection molding or direct write additive manufacturing. In this study, aqueous silicon nitride suspensions up to 45 vol% solids loading were dispersed using commercially available comb‐type copolymer. These copolymers are used as superplasticizers in the concrete industry and are referred to as water‐reducing admixtures (WRAs). Four different WRA dispersants were examined and chemical analysis determined that each was made up of a sodium salt of polyacrylic acid (PAA‐Na) backbone with neutral polyethylene oxide (PEO) side chains that afford steric stabilization. The general structures of the WRAs were compared to each other by measuring the relative areas of their prominent FTIR peaks and calculating a PAA‐Na/PEO peak ratio. Suspensions were made with as‐received silicon nitride powders with 5 wt% aluminum oxide and 5 wt% yttrium oxide added as sintering aids. Three of the four WRA dispersants studied were able to produce suspensions with 43 vol% solids loading and 5 vol% polymer dispersant, while exhibiting a yield‐pseudoplastic behavior up to 30 s−1. At higher solids loading (45–47 vol%), a shift to shear‐thickening behavior was observed at a critical shear rate for these WRAs. Those WRAs with a lower PAA‐Na/PEO peak ratio displayed better stabilization and diminished shear‐thickening behavior. The vol% of the dispersant was optimized producing yield‐pseudoplastic suspensions containing 45 vol% solids loading with yield stresses less than 75 Pa, no shear‐thickening behavior, and viscosities less than 75 Pa·s for shear rates in the range of 1–30 s−1.

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Section: Resultssupporting

confidence: 91%

Stabilizing Highly Loaded Silicon Nitride Aqueous Suspensions Using Comb Polymer Concrete Superplasticizers

2016

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“…Silicon nitride is another material that has been implemented as an EDL-inducing surface. 12,14,15 Both oxide and nitride thin films are common in microfabrication processes, where both films can be used as a͒ electronic insulators and passivators. Microfluidic channels based on the plasma-enhanced chemical vapor deposition ͑PECVD͒ of these films on planar substrates have recently been generated.…”

Section: Introductionmentioning

confidence: 99%

Electroosmotic flow in vapor deposited silicon dioxide and nitride microchannels

et al. 2007

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Electroosmotic flow was studied in thin film microchannels with silicon dioxide and silicon nitride sidewalls formed using plasma-enhanced chemical vapor deposition ͑PECVD͒. A sacrificial etching process was employed for channel fabrication allowing for cross-sections with heights of 3 m, ranging from 2 m to 50 m in width. Flow rates were measured for single channels and multichannel electroosmotic pump structures for pH levels ranging from 2.6 to 8.3, and zeta potentials were calculated for both silicon dioxide and silicon nitride surfaces. Flow rates as high as 0.086 L / min were measured for nitride multichannel pumps at applied electric fields of 300 V/mm. The surface characteristics of PECVD nitride were analyzed and compared to more well-known oxide surfaces to determine the density of amine sites compared to silanol sites.

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“…Y 2 O 3 satisfies the above mentioned requirements, and it is one of the additives studied extensively by several research groups. [42,43] Since, AlN powder is highly hydrolyzed in water, processing the AlN powder using the above mentioned methods is highly challenging. [33,34] However, chemical mixing has shown better homogenous mixing compared to the mechanical mixing.…”

Section: Homogeneous Dispersion Of Additivesmentioning

confidence: 99%

Processing and Characterization of Aluminum Nitride Ceramics for High Thermal Conductivity

2014

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The effects of sintering additives, microstructure, and morphology of second phase on the thermal conductivity of aluminum nitride ceramics are discussed in this review. The thermal conductivity of AlN is highly dependent on the types and amount of sintering additives, second phase morphology and microstructure. The morphology of second phase in AlN ceramics could be controlled by changing the cooling rate. The amount of second phase was able to be minimized by using the transient sintering additives. The thermal conductivity of AlN could be enhanced with the inclusion of the transient sintering additives. The thermal conductivity of AlN ceramics was evaluated by Raman spectroscopy. High temperature AC impedance studies were conducted to characterize the electrical conduction mechanism of AlN ceramics.

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Electrostatic Adsorption of a Colloidal Sintering Agent on Silicon Nitride Particles

Cited by 56 publications

References 6 publications

Stabilizing Highly Loaded Silicon Nitride Aqueous Suspensions Using Comb Polymer Concrete Superplasticizers

Stabilizing Highly Loaded Silicon Nitride Aqueous Suspensions Using Comb Polymer Concrete Superplasticizers

Electroosmotic flow in vapor deposited silicon dioxide and nitride microchannels

Processing and Characterization of Aluminum Nitride Ceramics for High Thermal Conductivity

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