Reply to comment on ?Effect of surface condition on the flexural strength of sintered silicon nitride?

1989 ◽  
Vol 8 (5) ◽  
pp. 620-620
Author(s):  
J. E. O. Ovri ◽  
T. J. Davies
Keyword(s):  
Silicon Nitride ◽  
Flexural Strength ◽  
Surface Condition ◽  
Sintered Silicon ◽  
Effect Of Surface

Sintered Reaction-Bonded Silicon Nitride by Microwave Heating

1992 ◽  
Vol 287 ◽  
Author(s):  
Terry N. Tiegs ◽  
James O. Kiggans ◽  
Kristin L. Ploetz
Keyword(s):  
Silicon Nitride ◽  
Flexural Strength ◽  
High Purity ◽  
Reaction Times ◽  
Raw Material ◽  
Firing Process ◽  
Step Process ◽  
Metal Parts ◽  
One Step ◽  
Sintered Silicon

ABSTRACTSintered silicon nitride has many desired properties, however, for most applications these materials are too expensive to compete with metal parts. Sintered reaction-bonded silicon nitride (SRBSN) is more economical, with raw material costs <27% those of comparable high-purity materials, making it competitive with metal parts. Conventional processing of SRBSN requires long nitridation times and a two-step firing process. Microwave (MW) heating reduces the reaction times and is performed in a one-step process, thereby simplifying the operation. The flexural strength of the MW-SRBSN is equivalent to the strength of some materials made from higher-cost powders. Thus, these materials may be appropriate for a number of applications.

scholarly journals Mechanical Strength Characterization of Sintered Silicon Nitride Containing Oxide Additives

1987 ◽  
Author(s):  
R. K. Govila
Keyword(s):  
Silicon Nitride ◽  
Flexural Strength ◽  
Crack Growth ◽  
Stress Rupture ◽  
Flexural Stress ◽  
Critical Crack ◽  
Temperature Oxidation ◽  
Temperature Range ◽  
Rupture Mode ◽  
Sintered Silicon

The flexural strength of a commercially available sintered silicon nitride (NGK-SN73) material containing various oxide additives (ceria, magnesia, zirconia and SrO) was determined in 4-point bending as a function of temperature (20 to 1200 C) in an air environment. Significantly, high strength (790 MPa) is maintained from room temperature to 800 C. At 900 C. and above, flexural strength decreased sharply. The sudden decrease in strength at temperatures of 900 and 1000 C is believed due to softening of the residual glass phase present in the material, and led to the presence of sub-critical crack growth. The extent of sub-critical crack growth and large viscous flow increased with increasing temperature (1100–1200 C) and led to degradation of material’s strength. In addition, the material was susceptible to oxidation at these temperatures as displayed by discoloration (dark gray to white) of the specimens. Extensive flexural stress rupture testing was carried out in the temperature range 800 to 1000 C in order to determine (i) the material’s susceptibility for low temperature oxidation instability, (ii) the presence of sub-critical crack growth at low temperatures (700 to 800 C) and high temperatures (900 to 1000 C) and (iii) to identify allowable stress levels for limited time (≤ 100 h) without showing degradation of materials strength (failure, creep or oxidation). Detailed fractographic evidence is presented to illustrate the type of strength controlling flaws present in the material at 20 C and above, and to reveal the presence of sub-critical crack growth displayed by the material in the temperature range 800 to 1000 C under stres-rupture mode.

ChemInform Abstract: OXIDATION OF THIN SHEET REACTION-SINTERED SILICON NITRIDE

1978 ◽  
Vol 9 (24) ◽  
Author(s):  
J. B. WARBURTON ◽  
J. E. ANTILL ◽  
R. W. M. HAWES
Keyword(s):  
Silicon Nitride ◽  
Thin Sheet ◽  
Sintered Silicon

Microstructure, toughness and flexural strength of self-reinforced silicon nitride ceramics doped with yttrium oxide and ytterbium oxide

2001 ◽  
Vol 201 (2) ◽  
pp. 238-249 ◽  
Author(s):  
Y. S. Zheng ◽  
K. M. Knowles ◽  
J. M. Vieira ◽  
A. B. Lopes ◽  
F. J. Oliveira
Keyword(s):  
Silicon Nitride ◽  
Flexural Strength ◽  
Yttrium Oxide ◽  
Ytterbium Oxide ◽  
Nitride Ceramics
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