A Stone Effigy from Long Island

1946 ◽  
Vol 11 (3) ◽  
pp. 200-201 ◽  
Author(s):  
Carlyle S. Smith
Keyword(s):  
Long Island ◽  
Crystalline Material ◽  
Stone Wall ◽  
Great Neck

In 1940, at Great Neck, Long Island, Mr. Calmer Forsander found a waterworn glacial cobble with a crudely executed face on one side in an old stone wall bordering his property. Mr. Forsander knew that I had excavated the Baker Hill site, located about three hundred yards west of his house, and brought the find to my attention. The specimen is roughly egg-shaped and is composed of a crystalline material which appears to be indurated sandstone (Fig. 24). It measures approximately IS inches in length, 11 inches in width, and 10 inches in thickness. On one of the broader sides is a face, pecked and ground into the surface. The workmanship is crude and resembles that found on the pitted hammer stones common in the region.

Low-temperature Mo-catalyzed growth of crystalline Si3N4 by CVD

1993 ◽  
Vol 51 ◽  
pp. 918-919
Author(s):  
K.L. More ◽  
R.A. Lowden ◽  
T.M. Besmann
Keyword(s):  
Vapor Deposition ◽  
Hot Isostatic Pressing ◽  
Chemical Vapor ◽  
Processing Method ◽  
Crystalline Material ◽  
Structural Ceramic ◽  
Alternative Processing ◽  
Strong Candidate ◽  
Hot Pressing Sintering ◽  
Processing Techniques

Silicon nitride possesses an attractive combination of thermo-mechanical properties which makes it a strong candidate material for many structural ceramic applications. Unfortunately, many of the conventional processing techniques used to produce Si3N4, such as hot-pressing, sintering, and hot-isostatic pressing, utilize significant amounts of densification aids (Y2O3, Al2O3, MgO, etc.) which ultimately lowers the utilization temperature to well below that of pure Si3N4 and also decreases the oxidation resistance. Chemical vapor deposition (CVD) is an alternative processing method for producing pure Si3N4. However, deposits made at temperatures less than ~1200°C are usually amorphous and at slightly higher temperatures, the deposition of crystalline material requires extremely low deposition rates (~5 μm/h). Niihara and Hirai deposited crystalline α-Si3N4 at 1400°C at a deposition rate of ~730 μm/h. Hirai and Hayashi successfully lowered the CVD temperature for the growth of crystalline Si3N4 by adding TiCl4 vapor to the SiCl4, NH3, and H2 reactants. This resulted in the growth of α-Si3N4 with small amounts of TiN at temperatures as low as 1250°C.

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