scholarly journals Physical-Mechanical Properties of γ-Irradiated SiC Ceramics for Radioactive Wastes Immobilization

2018 ◽  
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Radioactive Wastes ◽  
Γ Irradiation ◽  
Pressing Method ◽  
X Ray ◽  
Sic Ceramics ◽  
Radiation Resistant ◽  
Silicon Carbide Ceramics ◽  
Irradiation Process

The interest in silicon carbide (SiC-based) ceramics and composites as matrix material for nuclear waste immobilization is grown up. Long-term chemical durability and radiation resistance of SiC are important factors for radionuclides immobilization. Advantages of SiC-based ceramics as structural materials in nuclear applications are the high-temperature properties, high density and reduced neutron activation. The use of radiation resistant materials is a strong requirement for safe and environmentally beneficial energy system. The SiC ceramics stability under irradiation for temperatures up to 1273 K is also very important for nuclear power applications. The SiC matrices doped by additives of Cr, Si were fabricated using High Speed Hot Pressing Method. Additives content was in the range from 0.5 to 3 wt %. Microstructural characteristics of silicon carbide ceramics were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and infra-red spectroscopy (IR) methods. The results of microcracking under indentation conditions were revealed the lack of cracks in the SiC ceramics with Cr additives before and after irradiation process. In addition, it was demonstrated that samples of SiC with alloying additives Cr and Si possess high mechanical parameters under γ-irradiation process. The strength of ceramics increases with the uniform and fine-grained structure formation. The modification of phase composition and mechanical properties of the SiC ceramics with Cr and Si additives under γ-irradiation were analyzed for further development of radiation resistant and matrix materials for radioactive wastes immobilization.

Microstructure and Mechanical Properties of Heat-Resistant Silicon Carbide Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 1409-1413 ◽  
Author(s):  
Young Wook Kim ◽  
Yong Seong Chun ◽  
Sung Hee Lee ◽  
Ji Yeon Park ◽  
Toshiyuki Nishimura ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Intergranular Phase ◽  
Sintering Additives ◽  
Heat Resistant ◽  
Sic Ceramics ◽  
Microstructure And Mechanical Properties ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics

There has been a great progress in the development of heat-resistant silicon carbide ceramics, owing to the better understanding of composition-microstructure-properties relations. Based on the progress, it has been possible to fabricate heat-resistant SiC ceramics with improved fracture toughness. In this paper, three rare-earth oxides (Re2O3, Re=Er, Lu, and Sc) in combination with AlN were used as sintering additives for a β-SiC containing 1 vol% α-SiC seeds. The effect of intergranular phase, using Re2O3 and AlN as sintering additives, on the microstructure and mechanical properties of liquid-phasesintered, and subsequently annealed SiC ceramics were investigated. The microstructure and mechanical properties were strongly influenced by the sintering additive composition, which determines the chemistry and structure of IGP. The strength and fracture toughness of the Lu2O3-doped SiC were ∼700 MPa at 1400oC and ∼6 MPa.m1/2 at room temperature, respectively. The beneficial effect of the new additive compositions on high-temperature strength was attributed to the crystallization of the intergranular phase.

Effects of Vickers Cracks on the Mechanical Properties of Solid-phase-sintered Silicon Carbide Ceramics

2012 ◽  
Vol 27 (9) ◽  
pp. 965-969
Author(s):  
Xiao YANG ◽  
Xue-Jian LIU ◽  
Zheng-Ren HUANG ◽  
Gui-Ling LIU ◽  
Xiu-Min YAO
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Solid Phase ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics ◽  
Sintered Silicon

scholarly journals Study on Microstructure and Mechanical Properties of Al7068 Reinforced with Silicon Carbide and Fly Ash by Powder Metallurgy

2021 ◽  
Vol 7 (09) ◽  
pp. 47-53
Author(s):  
Md Mehtab Alam and B.S Motgi
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Fly Ash ◽  
Powder Metallurgy ◽  
Aluminum Matrix ◽  
Hydraulic Press ◽  
Powder Form ◽  
X Ray ◽  
Microstructure And Mechanical Properties ◽  
Scanning Electron

The paper deals with detailed study on microstructure and mechanical properties of aluminum 7068 reinforced with fly ash and silicon carbide by powder metallurgy, aluminum 7068, silicon carbide and fly ash were taken in powder form of required size and mixed together in varying proportion according to specification and compacted with pressure of 400MPa using hydraulic press to make samples and then samples were sintered at 600°c for 2 hours, the samples were tested for density, compressive strength, hardness and microstructure was analyzed using scanning electron microscope, energy dispersive x-ray study was carried out in order to confirm presence of silicon carbide and fly ash in aluminum matrix.

On the Role of Grain-Boundary Films in Optimizing the Mechanical Properties of Silicon Carbide Ceramics

2004 ◽  
Vol 818 ◽  
Author(s):  
R. O. Ritchie ◽  
X.-F. Zhang ◽  
L. C. De Jonghe
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Grain Boundary ◽  
Elevated Temperatures ◽  
Boundary Structure ◽  
Intergranular Films ◽  
Grain Boundary Structure ◽  
Silicon Carbide Ceramics

AbstractThrough control of the grain-boundary structure, principally in the nature of the nanoscale intergranular films, a silicon carbide with a fracture toughness as high as 9.1 MPa.m1/2 has been developed by hot pressing β-SiC powder with aluminum, boron, and carbon additions (ABC-SiC). Central in this material development has been systematic transmission electron microscopy (TEM) and mechanical characterizations. In particular, atomic-resolution electron microscopy and nanoprobe composition quantification were combined in analyzing grain boundary structure and nanoscale structural features. Elongated SiC grains with 1 nm-wide amorphous intergranular films were believed to be responsible for the in situ toughening of this material, specifically by mechanisms of crack deflection and grain bridging. Two methods were found to be effective in modifying microstructure and optimizing mechanical performance. First, prescribed post-annealing treatments at temperatures between 1100 and 1500°C were seen to cause full crystallization of the amorphous intergranular films and to introduce uniformly dispersed nanoprecipitates within SiC matrix grains; in addition, lattice diffusion of aluminum at elevated temperatures was seen to alter grain-boundary composition. Second, adjusting the nominal content of sintering additives was also observed to change the grain morphology, the grain-boundary structure, and the phase composition of the ABC-SiC. In this regard, the roles of individual additives in developing boundary microstructures were identified; this was demonstrated to be critical in optimizing the mechanical properties, including fracture toughness and fatigue resistance at ambient and elevated temperatures, flexural strength, wear resistance, and creep resistance.

scholarly journals The Effect of Excess Carbon on the Crystallographic, Microstructural, and Mechanical Properties of CVD Silicon Carbide Fibers

2006 ◽  
Vol 982 ◽  
Author(s):  
James V Marzik ◽  
William J. Croft ◽  
Richard J. Staples ◽  
Warren J. MoberlyChan
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Silicon Carbide ◽  
Elastic Modulus ◽  
Chemical Vapor ◽  
High Strength ◽  
Excess Carbon ◽  
X Ray ◽  
Silicon Carbide Fibers ◽  
Sic Fiber

ABSTRACTSilicon carbide (SiC) fibers made by chemical vapor deposition (CVD) are of interest for organic, ceramic, and metal matrix composite materials due their high strength, high elastic modulus, and retention of mechanical properties at elevated processing and operating temperatures. The properties of SCS-6™ silicon carbide fibers, which are made by a commercial process and consist largely of stoichiometric SiC, were compared with an experimental carbon-rich CVD SiC fiber, to which excess carbon was added during the CVD process. The concentration, homogeneity, and distribution of carbon were measured using energy dispersive x-ray spectroscopy (SEM/EDS). The effect of excess carbon on the tensile strength, elastic modulus, and the crystallographic and microstructural properties of CVD silicon carbide fibers was investigated using tensile testing, x-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Sign in / Sign up

Export Citation Format

Share Document