Structure, Formation, and Stability of Oxynitride Glasses

Loehman, Ronald E.

doi:10.1007/978-94-011-0992-5_12

Cited by 6 publications

(2 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, oxynitride glasses are harder and tougher when the nitrogen content increases. 27 Nevertheless, high-temperature fracture experiments still revealed significant degradation of creep and crack-growth resistance, which indicates that the mechanical properties are not improved by changing the film composition in this way. 29…”

Section: (2) Force-balance Modelmentioning

confidence: 99%

Dopant Distribution in Grain‐Boundary Films in Calcia‐Doped Silicon Nitride Ceramics

Pan

Cannon

et al. 1998

Journal of the American Ceramic Society

View full text Add to dashboard Cite

Quantitative analyses of the local chemistry of amorphous films at the grain boundary (GB) were taken on hot isostatically pressed high-purity Si 3 N 4 doped with various amounts of calcium (up to 450 ppm). This work was mainly accomplished by using spatially resolved electron energyloss spectroscopy (EELS) in a dedicated scanning transmission electron microscope. The amount of calcium segregation, quantified in terms of GB excess, saturated in the films at a bulk-doping level of ∼220 ppm. Extra additives did not stay at the triple-point glass pockets, where the calcium was almost expelled completely; instead, the additives stayed at intersections between the films and pockets. Otherwise, the calcium distribution was uniform along and across GB films. The latter was determined from simulations of EELS profiling. At grain/pocket interfaces, a much-lower segregation level occurred, ranging from one-half to one-tenth of the level at the GB. This observation indicates different segregation mechanisms in the two cases. Also, the calcium segregation in GB films changed the film composition dramatically, because more N 3− ions were introduced and replaced O 2− ions, to maintain the local stoichiometry. Reduction of the Van der Waals force has been proposed as being the origin of the film expansion with increasing calcium content.

show abstract

Section: (2) Force-balance Modelmentioning

confidence: 99%

Dopant Distribution in Grain‐Boundary Films in Calcia‐Doped Silicon Nitride Ceramics

Pan

Cannon

et al. 1998

Journal of the American Ceramic Society

View full text Add to dashboard Cite

show abstract

“…Therefore, N 2 atmosphere seems to restrain not only the grain growth but also the densification because the dissolution of nitrogen into the liquid phase increases the viscosity and inhibits the densification. 27 Meanwhile, a dense SiCPA could be obtained at a sintering temperature 1750°C in Ar with the addition of 5 wt-% of sintering additives without the presence of nitrogen. The hardness of SiCPN, SiCPA and NCSiC were 22.4, 24.0 and 24.5 GPa, respectively.…”

Section: Resultsmentioning

confidence: 99%

Effect of sintering atmosphere on the grain growth and hardness of SiC/polysilazane ceramic composites

Noviyanto

Yoon

Han

et al. 2016

Advances in Applied Ceramics

View full text Add to dashboard Cite

Silicon carbide (SiC) monoliths were synthesised using nano-size SiC powder mixed with/without polysilazane by hot pressing at 1750°C for 1 h under an applied pressure of 20 MPa in N 2 or Ar atmosphere. The effects of polysilazane and sintering atmosphere on the microstructure and hardness of SiC were examined. The grain sizes of the SiC ceramics sintered in N 2 atmosphere with and without the polysilazane were 161 and 605 nm, while the density for those samples were 96.5 and 98.1%, respectively. It was shown that Si 2 N 2 O was formed for the SiC/ polysilazane composite and sintered in N 2 . In addition, the sample mixed with polysilazane followed by sintering in N 2 atmosphere revealed a quite high hardness in spite of its relatively low density. It was suggested that Si 2 N 2 O phase played an important role for the inhibition of grain and subsequent high hardness.

show abstract