Sintering of β-Si3N4 Powder Prepared by Self-Propagating High-Temperature Synthesis (SHS)

2007 ◽  
Vol 546-549 ◽  
pp. 2179-2182 ◽  
Author(s):  
Ling Bai ◽  
Xing Yu Zhao ◽  
Chang Chun Ge
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Bending Strength ◽  
Sintering Process ◽  
Hot Press ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Good Sinter ◽  
The Cost ◽  
Hot Press Sintering

Sintering of the Self-Propagating High-Temperature Synthesis (SHS) of β-Si3N4 powder with 6.67 wt.% Y2O3 and 3.33 wt.% Al2O3 as sintering additives has been emphatically investigated using hot-press sintering process. The relative density of hot-pressed β-Si3N4 reached near to the full densification (99.43%) at 1700°C. The similar micrographs with self-reinforcing rod-like β-Si3N4 grains forming an interlocking structure were observed. The better mechanical properties of hot-pressed Si3N4, such as the hardness (16.73GPa), fracture toughness (5.72 MPa·m1/2) and bending strength (611.72MPa) values, were obtained at 1700°C. The results indicate that good sinter ability can be obtained with the cheaply SHS of silicon nitride powder for preparing silicon nitride materials, which will make the cost of silicon nitride materials lowered.

Fabrication of BN-AlN-TiB2 Compound Conductive Ceramics by Self-Propagating High Temperature Synthesis and Hot Isostatic Pressing

2007 ◽  
Vol 336-338 ◽  
pp. 786-789 ◽  
Author(s):  
Li Juan Zhou ◽  
Yong Ting Zheng ◽  
Shan Yi Du
Keyword(s):  
High Temperature ◽  
Composition Dependence ◽  
Bending Strength ◽  
Hot Isostatic Pressing ◽  
Microstructural Analysis ◽  
Temperature Synthesis ◽  
Powder Mixtures ◽  
Isostatic Pressing ◽  
High Temperature Synthesis ◽  
Conductive Ceramics

BN-AlN-TiB2 compound conductive ceramics from powder mixtures of BN, Al, and TiB2 was fabricated by self-propagating high temperature synthesis (SHS) and hot isostatic pressing (HIP). The powder mixtures were shaped by isostatic cool pressing at 5-10MPa and the combustion reaction was carried at 100-200 MPa N2 by an ignitor. XRD experiments confirmed that the reaction was complete and only AlN, BN and TiB2 were detected. Optical microscopy as well as SEM with an electron probe microanalysis was used for microstructural analysis and revealed a relatively uniform distribution of particulates. The temperature-dependence and composition-dependence of the electrical resistivity of BN-AlN-TiB2 ceramics were studied. The results showed that the optimum composition was 5-10wt% BN, 30-55wt% Al and 60-40wt% TiB2, and the products had the density of 90% of the theoretical, resistivity of 80-1000 μ⋅cm and bending strength of 100-200 MPa.

Effect of Dilution and Porosity on Self-Propagating High-Temperature Synthesis of Silicon Nitride

2002 ◽  
Vol 85 (9) ◽  
pp. 2209-2211 ◽  
Author(s):  
Irene G. Cano ◽  
Inna P. Borovinskaya ◽  
Miguel A. Rodriguez ◽  
Vladimir V. Grachev
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Temperature Synthesis ◽  
High Temperature Synthesis

scholarly journals Self-Propagating High-Temperature Synthesis of Silicon Carbide and Silicon Nitride Nanopowders Composition using Sodium Azide and Halides

2013 ◽  
Vol 16 (1) ◽  
pp. 41 ◽  
Author(s):  
Yu.V. Titova ◽  
A.P. Amosov ◽  
G.V. Bichurov ◽  
D.A. Maidan
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Silicon Nitride ◽  
Combustion Synthesis ◽  
Sodium Azide ◽  
Average Particle Size ◽  
Average Particle ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Working Volume

<p>Regularities of self-propagating high-temperature synthesis (SHS) or combustion synthesis (CS) by using “silicon – sodium azide – ammonium hexafluorosilicate – carbon – aluminum” powder mixture in the nitrogen atmosphere were investigated. The thermodynamic analysis of the combustion synthesis was performed. Experimental investigation of the combustion process: the measurement of linear rates of the combustion front propagation and the maximum combustion temperatures was conducted in a laboratory reactor with working volume 4.5 liters. The influence of the components ratio in the initial mixture on the combustion temperature, combustion rate and composition of reaction product was studied. The phase composition of the product synthesized was determined with an X-ray  diffractometer. It was disclosed that the SHS product consists of the composition (mixture) of silicon carbide nanopowder with silicon nitride whiskers and a final halide. Investigation of surface topography and morphology of the product particles was carried out with a scanning electron microscope. Optimal mixture for the synthesis of nanoscale composition based on silicon carbide was determined: “14Si+6NaN<sub>3</sub>+(NH<sub>4</sub>)<sub>2</sub>SiF<sub>6</sub>+15C+Al”. In this case, the SHS product consists of four phases: silicon carbide (β-SiC) – 48.57 wt.%, α-silicon nitride (<em>α</em>-Si<sub>3</sub>N<sub>4</sub>) – 27.04 wt.%, β-silicon nitride (β-Si<sub>3</sub>N<sub>4</sub>) – 5.83 wt.%, and sodium hexafluoroaluminate (Na<sub>3</sub>AlF<sub>6</sub>) – 18.56 wt.%. The average particle size of the composition was in the range of 70–130 nm. It was shown that the composition of the silicon carbide with silicon nitride and the final halide Na<sub>3</sub>AlF<sub>6</sub> playing a role a flux can be used as a modifier of castable aluminum alloys and as a reinforcing phase of aluminomatrix composites.</p>

A Comparative Investigation of the Porous NiTi Alloys Synthesized by Self-Propagating High-Temperature Synthesis and Combined Process of Decomposition and Sintering

2019 ◽  
Vol 889 ◽  
pp. 211-215
Author(s):  
Dang Thuy Nguyen ◽  
Ho Ky Thanh ◽  
Tran Van Dung
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
High Temperature ◽  
Processing Parameters ◽  
Sintering Process ◽  
Temperature Synthesis ◽  
Combined Process ◽  
Niti Alloys ◽  
Porous Niti ◽  
High Temperature Synthesis

Porous NiTi alloys were successfully synthesized by two different processes, including self-propagating high-temperature synthesis (SHS), and a combined process of decomposition – sintering. A systematic comparison of micro-structures and mechanical properties of these alloys was investigated. The results showed that the SHS process was better than decomposition – sintering process. By controlling the processing parameters of SHS, the received porous NiTi alloys showed that the porosity and pore were larger, and ratio of opened-pore reached up to 80%. The porous NiTi alloys fabricated by SHS process also exhibited good properties, such as a high compressive strength (up to 250MPa), and elastic modulus in range of 6.1 – 7.0GPa. The porous NiTi alloys synthesized by decomposition – sintering process have lower porosity (26-43%), lower compressive strength (< 110MPa), lower elastic modulus (< 1.2GPa) but the strain could be reached to 10%.

Gaseous nature of the reaction of Si–N bond formation in self-propagation high-temperature synthesis of silicon nitride by means of an azide method

2009 ◽  
Vol 19 (1) ◽  
pp. 45-46
Author(s):  
Nikolai M. Rubtsov ◽  
Boris S. Seplyarskii ◽  
Georgii V. Bichurov ◽  
Victor I. Chernysh ◽  
Georgii I. Tsvetkov
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Bond Formation ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Azide Method

Surface of powders of silicon nitride produced by self-propagating high-temperature synthesis

1984 ◽  
Vol 23 (1) ◽  
pp. 46-51
Author(s):  
Yu. M. Shul'ga ◽  
V. M. Martynenko ◽  
T. M. Moravskaya ◽  
I. P. Borovinskaya ◽  
A. G. Merzhanov ◽  
...  
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Temperature Synthesis ◽  
High Temperature Synthesis

Solid Phase’s Transformations in Boron Carbide Based Composites during Heat Treatment

2008 ◽  
Vol 138 ◽  
pp. 175-180
Author(s):  
Lembit A. Kommel ◽  
Eduard Kimmari
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Boron Carbide ◽  
Environmental Conditions ◽  
Sliding Wear ◽  
Bending Strength ◽  
Reaction Products ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Different Temperatures

Lightweight B4C/Al composites were produced from powders of boron carbide and aluminum by self-propagating high-temperature synthesis (SHS). The effects of postdensification heat treatment at different temperatures and environmental conditions on phase transformations and properties evolution were studied. Heat treatment processing that followed the synthesis was applied using low heating rate in temperature range from 400°C up to 1500°C. An interconnected multiphase (B4C, Al3BC, and c-BN) microstructure was produced in composite as a result of heat treatment at temperatures below 1080°C. The formation of hard and brittle reaction products (AlN, AlB2, Al4C3, and Al8B4C7) at temperatures above 1150°C causes decrease in bending strength and increase in resistance to unlubricated sliding wear.

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