Densification studies of silicon carbide-based ceramics with yttria, silica and alumina as sintering additives

Abstract

Si li con car bi de has been ex ten si vely used in struc tu ral ap pli ca ti ons, es pe ci ally at high tempe ra tu res. In this work, Y 2O3, Al 2O3 and SiO 2 were ad ded to β-SiC in or der to ob ta in highly den se ce ra mics. Sin te ring was con duc ted in a di la to me ter and in a grap hi te re sis tan ce fur na ce and the den si fi ca ti on be ha vi our was stu di ed. Sin te red sam ples were cha rac te ri sed b y den sity me a su re ments, the crystal li ne pha ses were iden ti fi ed by X-ray dif frac ti on. Mi cros tru c tu ral obser va ti on of po lis hed and po lis hed/et ched sam ples was car ri ed out with help of scan ning electron mi cros copy. Si li con car bi de ce ra mics with more than 90% of the the o re ti cal den sit y were ob ta i ned by pres su re less sin te ring if a su i ta ble pro por ti on of the ad di ti ves is us ed. Key words : si li con car bi de, di la to me tric stu di es, li quid pha se sin te ring, ad di ti ves

Complex-shaped ceramic composites obtained by machining compact polymer-filler mixtures

“…This reaction leads to gaseous species, SiO and CO which may form in the Si-O-C system at higher temperatures (>1400 °C) 13 . The total linear shrinkage is less ( 8%) than that typically observed in conventional sintering processes (15 to 20 %) 15 .…”

Experimental Design Applied to Silicon Carbide Sintering

“…Details of this behavior are reported elsewhere. 20 The critical shrinkage peak occurs at Ϸ1800°C, hereafter labeled T1. Above this temperature, the shrinkage rate decreases, although microstructural changes are still taking place.…”

Bulk Yttria as a Host for Lanthanides in Biomedical Applications: Influence of Concentration Gradients on Structural, Mechanical, Optical, and in Vitro Imaging Behavior

“…It should be noted that ISO 13356 approves the use of yttria (Y 2 O 3 ) as the most suitable additive in medical use . Generally, Y 2 O 3 is used as an additive in a wide variety of high-performance materials for various purposes, namely low temperature phase stabilization, sintering aid, grain growth inhibitors, and to achieve enhanced mechanical stability. , Moreover, the use of rare earth (RE 3+ ) doped materials gained importance in various technological applications. , Y 2 O 3 as a host for RE 3+ has also been preferred as a multifunctional material owing to its unique physiognomies like thermal stability, chemical durability, and low phonon energy. , The common valence states and crystal structure similarities are also considered for Y 2 O 3 as a perfect host for RE 3+ . Among the three crystallographic forms of Y 2 O 3 at ambient conditions, C -type cubic is considered more stable than B -type monoclinic and A -type hexagonal structures …”