Title

De-Agglomeration Study And Slip Casting Of Tungsten Nanopowders Via Aqueous Colloidal Processing

Abstract

To deliver the high green density of tungsten nanoparticle packing, tungsten nanopowders were de-agglomerated in water and slip cast in plaster molds. De-agglomeration was carried out by using an ultrasonic probe in aqueous solution, followed by repeated washing, and pH adjustment. The change in particle size and morphology was observed by using SEM. It was determined that after removing the initial surface oxide by repeated washing, that the reactivity of tungsten nanoparticles to water was somewhat inhibited, and the degree of de-agglomeration and stability of tungsten nanopowder in suspension was increased. The optimum pH was obtained by measuring the viscosity of the slurry as a function of pH values. It was determined that a pH of around 5 was the optimum to obtain the highest solids loading and lowest viscosity of a tungsten nanopowder slurry. At about 30 vol.% solids loading, the relative density of the slip cast green pellet was about 44%, which is higher than a uniaxially-pressed pellet consolidated at a pressure of 618 MPa (42%). Cold isostaic pressing can further increase the green density significantly following slip casting. After sintering, slip cast samples exhibited a more uniform structure, finer grain size, and much smaller pores than samples dry pressed prior to sintering.

Publication Date

12-1-2008

Publication Title

Proceedings of the 7th International Conference on Tungsten, Refractory and Hardmaterials

Number of Pages

578-589

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

Socpus ID

84883248922 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84883248922

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