摘要 |
An ultra strong, hollow sintered, impervious, metallic shell for use in structural applications including proppants for hydraulic fracturing. The shell is made of a maraging steel, low alloy steel, or stainless steel with a crush strength of about 3,000 psi or greater and a density of about 0.6 g/cm3 to about 2.5 g/cm3.
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