Formation of an α‐SiAlON Layer on ß‐SiAlON and Its Effect on Mechanical Properties

Abstract

We have developed a technique for in situ formation of an ␣-SiAlON layer on sintered ␤-SiAlON. The technique consists of packing a powder compact of ␤-SiAlON composition with ␣-SiAlON composition powder, presintering, and sintering. Using this technique, it is possible to control the thickness of the layer by changing the presintering conditions during heating to a sintering temperature. The introduction of an ␣-SiAlON layer increases the surface hardness and improves the wear and oxidation resistance, with a moderate reduction of flexural strength. The surface modification of ␤-SiAlON may provide opportunities of wider application of ␤-SiAlON to wear-and oxidationresistant components.

Effect of cubic boron nitride grain size in the reinforcing of α-Sialon ceramics sintered via SPS

“…For the calculation of the fracture toughness a Young's modulus of 300 GPa was used for the Sialon matrix. 20,21 However in the case of Sialon/ABN composites, the large ABN300 grains are significantly larger than the size of the indentations generated when using the Vickers hardness test method. This resulted in a wide distribution of hardness values.…”

Spark plasma sintering: A powerful tool to develop new silicon nitride-based materials

“…30,31 Most of the published works on Si 3 N 4 -based FGMs consist in layered systems step-wise fabricated by stacking a number of layers with gradual variations in particle size or composition. [33][34][35][36] However, this processing method is cumbersome for mass production, and more prone to the nucleation of interfacial stresses that would compromise the reliability of the component under operating conditions. Present authors 32 processed continuous in situ functionally graded Si 3 N 4 materials from a sole homogenous starting composition using an asymmetric arrangement of the SPS graphite punches to get a temperature gradient, which turned into ␣/␤ ratio 32 and, therefore, into property gradation through the Si 3 N 4 specimen.…”

Electronic Structure and Bonding of β‐SiAlON

“…Needless to say, this problem has attracted many researchers using different techniques to elucidate the structure, composition, and behavior of the intergranular phases in Si 3 N 4 . [21][22][23][24][25][26] Despite these endeavors, no clear understanding has emerged. Experimental development is usually conducted by a trial-and-error approach.…”