Fabrication of Functionally Graded SiAlON Ceramics by Tape Casting

Abstract

Functionally graded SiAlON ceramics (FG-SiAlONs) were successfully prepared by the tape casting and lamination approach. Non-aqueous SiAlON slurries with five different a to b-SiAlON ratios (85a:15b, 70a:30b, 55a:45b, 40a:60b, and 25a:75b) were prepared by a 66 methyl ethyl ketone/34 ethanol (vol%) mixture. Phase and microstructure analyses incorporation with hardness measurements clearly show that the FG-SiAlONs, prepared by tape casting, exhibit a continuous and gradual change in composition and hardness. Thus, the tape casting approach is a viable method to produce FG-SiAlONs with a precisely controlled composition, and subsequently properties, as a function of position.

The effect of the wet-milling process on sintering temperature and the amount of additive of SiAlON ceramics

“…The solvent compositions were determined according to literature studies [7][8][9][10][11][12]. The sedimentation method was used for determination of an adequate dispersion in order to use ball milling energy to decrease the particle size of the starting powders.…”

“…Thus, in an agglomerate-free system, energy will be transferred to the powder to decrease particle size. There are few studies [7][8][9][10] investigating well-dispersed suspension systems for SiAlON ceramics but these did not include any comparison between solvent and dispersant types. In this study, SiAlON powders milled in different solvent mediums (toluene, methyl ethyl ketone, and ethanol) with different kinds of dispersants (oleic acid, poly ethylene glicol, sodium tripolyphosphate) and sedimentation tests were performed.…”

Dense β-SiAlONs consolidated by a modified hydrolysis-assisted solidification route

“…6,7 However, this technique has been found to be difficult and quite expensive particularly for making large size and complex shaped components. In order to make components with high density and high uniformity, and thus, high reliability of performance, a great variety of aqueous based colloidal forming techniques such as, slip casting, 8 tape casting, 9 gelcasting, 10,11 temperatureinduced forming process, 12 hydrolysis-assisted solidification (HAS), [13][14][15] techniques, aqueous gelcasting was found to be one of the most effective routes for making near net-shape parts with relatively high green strength. 16 However, as the organic monomers used in this process are very expensive, this process is not viable for making many of the commercially important products to be fabricated in large quantity.…”

A review of the processing, composition, and temperature-dependent mechanical and thermal properties of dielectric technical ceramics

“…β -sialon is the most widely used sialon, with higher fracture toughness (≈ 7-8 MPa·m 1 2 for β -sialon, ≈ 3-4 MPa·m 1 2 for α -sialon [74]) and room temperature strength, but lower hardness (≈ 1500-1700 kg·mm −2 H v for β -sialon, ≈ 1900-2100 kg·mm −2 H v for α -sialon) and thermal shock resistance than α -sialon [71,75,76]. A good combination of strength, hardness, and fracture toughness, intermediate to those of monolithic α and β -sialons, can be obtained from duplex sialons [75], with hardness and thermal shock resistance increasing and toughness decreasing with increasing α -phase content [71,77].…”