Thermodynamic analysis of the high-temperature stability of silicon nitride and silicon carbide

The paper reports morphology and structure transitions of silicon carbide (SiC) nanowires during high temperature annealing; the as-prepared nanowires are in the form of SiC core and SiO2 shell. The transition temperature is about 1200 °C, 600 °C lower than that of SiC microfibers, and it starts with the formation of junctions of individual nanowires. The junctions grow into webs while the crystalline SiC cores of the nanowires oxidize. The growth and the oxidation eventually lead to the formation of an oxide film, when the transition completes. The thermal stability and the transition mechanisms of SiC nanowires are critical to their applications in high temperature environments.

Download Full-text

High Temperature Stability of Fepure-Si3N4 in Reducing Atmosphere

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.952.11 ◽

2014 ◽

Vol 952 ◽

pp. 11-15

Author(s):

Bin Li ◽

Jun Hong Chen ◽

Jin Dong Su

Keyword(s):

High Temperature ◽

Silicon Nitride ◽

Temperature Stability ◽

High Temperature Stability ◽

Reducing Atmosphere ◽

Xrd Diffraction ◽

Calculation Results ◽

Different Temperatures ◽

The Stability ◽

Main Components

Iron and silicon nitride powders were mixed in a certain proportion and compacted, then Fepure-Si3N4 were prepared by heating the samples in reducing atmosphere at 1100°C, 1300°C and 1500 °C, respectively. The stability of Fepure-Si3N4 prepared at different temperatures was analyzed by XRD diffraction and theoretical thermodynamics calculation. Results show that the main components of Fepure-Si3N4 at high temperatures in reducing atmosphere are Si3N4 and Si2N2O; Iron exists in Fepure-Si3N4 at 1100°C, and iron had largely converted to Fe3Si phase at 1300°C and 1500°C, which is in accordance with the result of thermodynamic theoretical calculation.

Download Full-text

UNS N06455

Alloy Digest ◽

10.31399/asm.ad.ni0367 ◽

1989 ◽

Vol 38 (1) ◽

Keyword(s):

Corrosion Resistance ◽

High Temperature ◽

Stress Corrosion Cracking ◽

Temperature Stability ◽

Heat Treating ◽

High Ductility ◽

High Temperature Stability ◽

Nickel Chromium ◽

Long Time ◽

Resistance To Stress

Abstract UNS NO6455 is a nickel-chromium-molybdenum alloy with outstanding high-temperature stability as shown by high ductility and corrosion resistance even after long-time aging in the range 1200-1900 F. The alloy also has excellent resistance to stress-corrosion cracking and to oxidizing atmospheres up to 1900 F. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-367. Producer or source: Nickel and nickel alloy producers.

Download Full-text

UNS R54620

Alloy Digest ◽

10.31399/asm.ad.ti0086 ◽

1987 ◽

Vol 36 (7) ◽

Keyword(s):

Titanium Alloy ◽

High Temperature ◽

Time Use ◽

Temperature Stability ◽

High Strength ◽

Heat Treating ◽

High Temperature Stability ◽

Beta Titanium Alloy ◽

Beta Titanium ◽

Long Time

Abstract UNS No. R54620 is an alpha-beta titanium alloy. It has an excellent combination of tensile strength, creep strength, toughness and high-temperature stability that makes it suitable for service to 1050 F. It is recommended for use where high strength is required. It has outstanding advantages for long-time use at temperatures to 800 F. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and bend strength as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ti-86. Producer or source: Titanium alloy mills.

Download Full-text