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 Preparing High-Purity Anhydrous ScCl3 Molten Salt Using One-Step Rapid Heating Process

2020 ◽  
Vol 10 (15) ◽  
pp. 5174
Author(s):  
Junhui Xiao ◽  
Chao Chen ◽  
Wei Ding ◽  
Yang Peng ◽  
Kai Zou ◽  
...  
Keyword(s):  
Molten Salt ◽  
High Purity ◽  
Rapid Heating ◽  
Raw Material ◽  
Hydrolysis Rate ◽  
Heating Process ◽  
Crystal Water ◽  
Argon Flow ◽  
One Step ◽  
Scandium Chloride

In this study, a one-step rapid heating novel process was used to prepare high-purity anhydrous scandium chloride molten salt with low-purity scandium oxide. High-purity anhydrous ScCl3 molten salt was used as the Sc-bearing raw material for preparing the Sc-bearing master alloy. Inert gas was used to enhance the purity of anhydrous scandium chloride and reduce the hydrolysis rate of scandium. The results show that high-purity scandium chloride (purity, 99.69%) with the scandium content of 29.61%, was obtained, and the hydrolysis rate of scandium was 1.19% under the conditions used: removing ammonium chloride; residual crystal water temperature of 400 °C; m(Sc2O3):m(NH4Cl) = 1:2.5; holding-time of 90 min; heating-rate of 12 °C/min; and argon flow of 7.5 L/min. XRD, SEM, and EPMA analyses further verified that anhydrous scandium chloride crystallization condition was relatively good and the purity of high-purity anhydrous scandium chloride approached the theory purity of anhydrous scandium chloride.

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.

scholarly journals Comparison of Properties of Sintered and Sintered Reaction-Bonded Silicon Nitride Fabricated by Microwave and Conventional Heating

1994 ◽  
Vol 347 ◽  
Author(s):  
Terry N. Tiegs ◽  
James O. Kiggans ◽  
H. T. Lin ◽  
Craig A. Willkens
Keyword(s):  
Silicon Nitride ◽  
Grain Growth ◽  
Raw Materials ◽  
Cost Effective ◽  
Conventional Heating ◽  
Structural Applications ◽  
One Step ◽  
Powder Compacts ◽  
Fabrication Parameters ◽  
Sintered Silicon

ABSTRACTA comparison of microwave and conventional processing of silicon nitride-based ceramics was performed to identify any differences between the two, such as improved fabrication parameters or increased mechanical properties. Two areas of thermal processing were examined: (1) sintered silicon nitride (SSN) and (2) sintered reaction-bonded silicon nitride (SRBSN). The SSN powder compacts showed improved densification and enhanced grain growth. SRBSN materials were fabricated in the microwave with a one-step process using cost-effective raw materials. The SRBSN materials had properties appropriate for structural applications. Observed increases in fracture toughness for the microwave processed SRBSN materials were attributable to enhanced elongated grain growth.

An effective way to stabilize silicon nitride nanoparticles dispersed in rubber matrix by a one-step process

2008 ◽  
Vol 112 (2) ◽  
pp. 659-667 ◽  
Author(s):  
Yanlong Tai ◽  
Jibin Miao ◽  
Jiasheng Qian ◽  
Ru Xia ◽  
Yuchuan Zhang
Keyword(s):  
Silicon Nitride ◽  
Rubber Matrix ◽  
Step Process ◽  
One Step

Instant 99mTc Compounds

1971 ◽  
Vol 10 (03) ◽  
pp. 245-251 ◽  
Author(s):  
P. Richards ◽  
W. C. Eckelman
Keyword(s):  
Physical Properties ◽  
High Purity ◽  
Analytical Techniques ◽  
Full Potential ◽  
Labeled Compounds ◽  
Ph Adjustment ◽  
One Step ◽  
Stannous Ion ◽  
99Mtc Radiopharmaceuticals ◽  
Potential Use

SummaryThe full potential use of technetium has not been achieved despite its ideal physical properties, dosimetry and availability because of the complex preparations required for 99mTc radiopharmaceuticals. One of the goals of our work is to develop techniques for the preparation of high-purity 99mTc compounds which can be easily prepared, ideally by adding pertechnetate to a prepared solution.The use of stannous ion as reducing agent for technetium makes it possible to obtain such one-step, high-purity products. All non-radioactive components can be premixed in a single vial before addition of the radioactive pertechnetate. No final pH adjustment, further chemical manipulation or purification is required.Procedures for two instantly labeled compounds have been developed to date: 99mTc DTPA and 99mTc HSA. The 99mTc DTPA is prepared by adding pertechnetate to a previously prepared solution of stannous ion and CaNa3 DTPA which has been stored at pH 4. The 99mTc HSA is prepared by adding pertechnetate to a solution of stannous ion and HSA. The parametric variations and analytical techniques involved in formulating these procedures are described. It appears that development of kits for other biologically interesting compounds may be possible using similar procedures.

SIFAT FISIS MEKANIS BAMBU LAPIS SEBAGAI BAHAN BAKU PRODUK INTERIOR

2011 ◽  
Vol 3 (1) ◽  
pp. 15
Author(s):  
Arhamsyah Arhamsyah
Keyword(s):  
Flexural Strength ◽  
Water Content ◽  
Raw Material ◽  
Technical Aspects ◽  
Material Layer ◽  
Weight Variation

Research on the utilization of bamboo as a raw material layer interior products have been made. This research aims to determine the nature of plybamboo in terms of technical aspects / processes of manufacture, physical and mechanical, the influence of weight variation labur adhesive, adhesive types and kinds of bamboo products plybamboo.This type of bamboo used is sweet bamboo (Gigantochloa atter Kurz) and bamboo lear (Gigantochloa apus Kurz).The adhesive used was adhesive Polyvinil Acetat (PVAc) and Chloroprene with adhesive labur weight each - each 150 gr/m2, 200 gr/m2 and 250 gr/m2. The parameters tested were water content, density, flexural strength of dry and delamination.The results showed that the treatment using bamboo material with adhesive Chloroprene sweet heavy labur 250 gr/m2 produce the best plybamboo.Keywords: bamboo, glue, physical, mechanical

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