Study of Sintering Parameters and Sintering Additives Effect on selected properties of Silicon Nitride

Abstract

The subject of this article is the study of influence of sintering time and sintering additives on mechanical properties and wear resistance. Si3N4 with Al2O3+Y2O3 additives (YAG) and Si3N4 with MgO additives was used as an experimental materials. Compositions sintered for 30 min achieved optimal combination the hardness and fracture toughness -15.05 GPa and 6.87 MPa.m 1/2 for Si3N4-MgO and 14.65 GPa and 5.71 MPa.m 1/2 for Si3N4 -YAG. Wear was mostly influenced by the hardness of ceramic materials. The specimen with the highest hardness achieved the highest wear resistance. Wear resistance of ceramics decreased with the grain growth and with the transformation progress of narrow α-Si3N4 phase to prismatic β-Si3N4 phase. The wear resistance of the studied ceramics can be described by model V ~ HV -1 . Si3N4 -YAG in comparison to Si3N4-MgO has several times greater wear resistance.

Effect of Mechanical Properties on Wear Resistance of Si3N4 – SiC Ceramic Composite

“…When abrasive wear is a predominant wear mechanism, parameter ratio K IC /HV can be used for prediction of wear of fragile materials [18,19]. Based on the value of the K IC / HV ratio, we can define the predominant wear mechanism in the contact.…”

“…Physical, mechanical, and tribological properties of this type of composite have been evaluated. The effects of chemical composition of the composite, used processing method, process parameters and morphology of secondary phase on these properties have been studied [10,[30][31][32][33][34]. The results of the works show that the mechanical properties depend on the microstructure of ceramic material.…”

“…Phase transformation from a-Si3N4 to β-Si3N4 occurs during sintering process of Si3N4 based ceramic materials [19]. Figure 10 documents portions of phases in experimental materials after hot pressing process.…”

“…From Table 1 the decrease of fracture toughness with increased portion of SiC can be seen. This effect could be caused the morphology of the matrix [19,32]. Prismatic β-Si 3 N 4 grains, which increase the fracture toughness, could not reach the prolongated morphology, as the SiC particles limited the growth of Si 3 N 4 grains.…”

Combustion of Ferrosilicon–Zircon Mixtures in Nitrogen Gas: Impact of Aluminum Additives

“…Due to their unique properties, silicon nitride (Si 3 N 4 ) and related composites (such as Si 3 N 4 -SiC, Si 3 N 4 -TiN, Si 3 N 4 -BN, Si 3 N 4 -MoSi 2 ) find wide application in mechanical engineering, cutting tools, chemistry, and radio electronics [1][2][3][4][5]. Since Si 3 N 4 is a hard-to-sinter material, several oxides have been suggested for use as sinter aids [6,7], including ZrO 2 [8][9][10].…”