Recrystallization sintering and characterization of composite powders composed of two types of SiC with dissimilar particle sizes

Abstract

Pure silicon carbide (SiC) ceramics were prepared through recrystallization sintering by using two types of SiC powder, with different particle sizes, as the raw materials. The effects of the fine powder content on the bulk density, porosity, flexural strength, and grain morphology were investigated. In the synthesis process, silicon nitride (Si3N4) was used as the sintering additive that decomposed and transformed into SiC to promote the growth of SiC grains. The added fine powder was exploited in the evaporation and condensation process and grain amalgamation caused by the movement of the grain boundaries. Thus, a dissimilar fine powder content modulated the microstructure and mechanical strength of the SiC ceramics. The results indicate that the bulk density and flexural strength increase to a maximum of 2.12 g/cm3, 44.2 MPa, respectively, when the fine powder content is 40 wt.%. Three kinds of grain morphologies, that is, uniform equiaxed grains, round, equiaxed grains, and hexagonal platelet grains, and the maximum average pore size (3.62 μm) are obtained when the fine powder content is between 0 wt.% and 60 wt.%. In addition, the main crystal phase 6H‐SiC is partially converted to 4H‐SiC when the fine powder content is up to 60 wt.%.

Effect of Post-Oxidation Treatment on the Performance and Microstructure of Silicon Carbide Ceramic Membrane

“…The particle packing approach, based on the recrystallization sintering process, is often used in the commercial production of SiC ceramic membranes [25]. The preparation of SiC ceramic membranes via recrystallization sintering usually consists of preparing a powder slurry, extrusion molding, high-heat sintering, and post-oxidation treatment (POT) [26][27][28].…”

New Strategy for Preparation of Yttria Powders with Atypical Morphologies and Their Sintering Behavior

“…In recent years, electric current pulse technology has been widely used for material preparation, especially to control the microstructure and refine the particle size of metal materials during solidification [ 15 , 16 , 17 ]. Crystallinity and particle size are important factors affecting the properties of powders, especially their sintering properties [ 18 , 19 ]. Therefore, applying a pulsed electric current during the preparation of yttria powders is expected to influence their crystallinity and particle size.…”

Adsorption and Dispersion Effect of Sodium Lignosulfonate on Fine SiC Particles in Aqueous Media

“…Because of the evaporation–condensation mechanism, the R–SiC body does not shrink during the recrystallization process . Noteworthily, the mechanical properties of R–SiC ceramics closely correlate with its density and microstructure . Therefore, the key to preparing high-performance R–SiC is obtaining a high-density green body, which can be actualized by a high-concentrated and well-dispersed SiC slurry during slip casting. , Slip casting is an extensively used forming method to produce complex-shaped ceramics in the industry .…”