Manufacture and examination of C/Si3N4 nanocomposites

Balázsi, Cs.; Çınar, Fırat; Addemir, O.; Wéber, Ferenc; Arató, Péter

doi:10.1016/j.jeurceramsoc.2003.10.021

Cited by 20 publications

(8 citation statements)

References 20 publications

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“…Several scientific works have studied this effect and found that the formation of oxide layer caused the degradation of material due which resulted the lower value of mechanical properties [13 -18]. Balazsi et al showed the role and the effect of excess oxygen in the <alpha> -Si 3 N 4 starting powder performed at 1000 °C in air for 150 h The oxidized samples was sintered by Hot isostatic pressing (HIP) at 1700 °C in high purity nitrogen at a low gas pressure of 20 bar for 1 h. They confirmed the presence of <beta> -Si 3 N 4 and Si 2 N 2 O phases in sintered samples and glassy phases appeared after sintering [19]. The base silicon nitride powder characteristics have a significant influence on the final properties of densified product.…”

Section: Introductionmentioning

confidence: 93%

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Effect of the oxidization of Si3N4 powder on the microstructural and mechanical properties of hot isostatic pressed silicon nitride

Qadir

Fogarassy

Horváth

et al. 2018

Ceramics International

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The effect of nanosized oxidized silicon nitride powder particles on the microstructural and mechanical properties of hot isostatic pressed silicon nitride was studied. The starting Si 3 N 4 powders were oxidized for 10 and 20 h at 1000 ˚C in ambient air environment. An amorphous oxide layer was observed on the surface of Si 3 N 4 powder particles using high resolution transmission electron microscopy (HRTEM) whose thickness increased with the oxidation time. The powders were hot isostatic pressed at 1500 ˚C and 1700 ˚C in nitrogen gas environment under 20 Mpa for 3h. Complete to transformation was observed in Si 3 N 4 samples sintered at 1700 C under 20 MPa for 3 h compared to Si 3 N 4 samples sintered at 1500 ˚C. Silicon oxynitride (Si 2 N 2 O) was found in sintered samples whose amount increased with the oxidation time. The phase decreased with the increase of Si 2 N 2 O phase in the sintered samples. The flexural strength of samples sintered at 1700 ˚C is higher due to the higher amount of -Si 3 N 4 phase than for samples sintered at 1500 ˚C. Decreasing flexural strength was observed with the oxidation time. Higher amount of oxygen in the base powders resulted in a higher Si 2 N 2 O content in the sintered Si 3 N 4 .

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Section: Introductionmentioning

confidence: 93%

“…The heating rate did not exceed 25 ˚C/ min. The dimensions of the as-sintered specimens were 3.5 mm x 5 mm x 50 mm [19].…”

Section: Experimental Details 21 Preparation Of Samplesmentioning

confidence: 99%

Effect of the oxidization of Si3N4 powder on the microstructural and mechanical properties of hot isostatic pressed silicon nitride

Qadir

Fogarassy

Horváth

et al. 2018

Ceramics International

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“…Accordingly the term r −6 dx 3 (see Eqs. (6), (14), (15)) is replaced by r −6 dr, where r ∈ R OP 3 and r ∈ x 1 OP 5 for x 1 ∈ 0 R and x 1 ∈ R d/2 , respectively.…”

Section: Figurementioning

confidence: 99%

“…As an important phenomenon observed in multi-phase materials, the thermal stresses influence mechanical properties [1][2][3][4][5][6][7], diffusion processes [8][9][10][11] as well as grain growth [12][13][14]. With regard to mechanical properties, on the one hand, the thermal stresses can represent resistance against mechanical loading.…”

Section: Introductionmentioning

confidence: 99%

“…With regard to mechanical properties, on the one hand, the thermal stresses can represent resistance against mechanical loading. On the other hand, as a consequence of a component dimension greater than critical, thermal-stress induced energy tends to be released by crack initiation and propagation [4][5][6][7]15]. In general, the thermal stresses as functions of a position given by the coordinate x 1 induce the x 1 -dependent energy density w accumulated in an arbitrary point in a multi-phase material.…”

Section: Introductionmentioning

confidence: 99%

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Analytical Models of Thermal-Stress Induced Phenomena in Isotropic Multi-Particle-Matrix System

Ceniga

2008

Journal of Thermal Stresses

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The paper presents four topics dealing with phenomena induced by elastic thermal stresses acting in an isotropic multi-particle-matrix system to represent a model system applicable to real multi-phase materials of a precipitation-matrix type. The isotropic multi-particle-matrix system consists of periodically distributed spherical particles in an infinite matrix to be imaginarily divided into cubic cells containing a central spherical particle. Formulae for the thermal stresses to be investigated within the cubic cell represents functions of the particle volume fraction v and the particle radius R. The thermal stresses originate during a cooling process as a consequence of the difference m − p in the thermal expansion coefficients m and p of the matrix and the particle, respectively. Additionally, such temperature range is considered within which the multi-particle-matrix system exhibits elastic deformations regarding the yield stress and the particle-matrix boundary adhesion strength. Analytical fracture mechanics to represent the first topic of this paper results from the determination of a curve integral of the thermal-stress induced elastic energy density. The curve elastic energy density results in the determination of the critical particle radii R pc and R mc as reasons of the crack initiation in the spherical particle and the matrix for m − p < 0 and m − p > 0, respectively. Consequently, the crack propagation to follow the crack initiation is a consequence of the particle radius R > R qc (q = p m). Finally, a shape of the crack in a plane perpendicular to the direction of the crack propagation in the particle (q = p) and the matrix (q = p) is described by the function f q related to the ideal-brittle components. With regard to the crack initiation, the analytical determination of the radius R qc is considered for any multi-phase materials of a precipitation-matrix type. With regard to the crack propagation, the analytical determination of the function f q along with an analysis concerning the crack dimension and directions of the crack propagation is considered for ceramic multi-phase materials which are generally assumed to be idealbrittle. The thermal stresses induce resistance against compressive or tensile mechanical 862 ANALYTICAL MODELS OF THERMAL-STRESS INDUCED PHENOMENA 863 loading for m − p > 0 or m − p < 0, respectively. The analytical determination of the resistance results from the elastic energy gradient to represent the second topic of this paper. Derived by two equivalent mathematical techniques, the gradient within the cubic cell is defined as a surface integral of the thermal-stress induced elastic energy density. Consequently the 'surface' elastic energy density results in the analytical determination of the system strengthening to represent the third topic of this paper. Representing the fourth topic of this paper, an analytical model of stresses originating in isotropic crystalline lattices are derived. The stresses in the lattices are a consequence of the presence of a central substit...

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Sintering of Porous Materials

Chen

2012

Sintering

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Manufacture and examination of C/Si3N4 nanocomposites

Cited by 20 publications

References 20 publications

Effect of the oxidization of Si3N4 powder on the microstructural and mechanical properties of hot isostatic pressed silicon nitride

Effect of the oxidization of Si3N4 powder on the microstructural and mechanical properties of hot isostatic pressed silicon nitride

Analytical Models of Thermal-Stress Induced Phenomena in Isotropic Multi-Particle-Matrix System

Sintering of Porous Materials

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