Abstract: The present invention relates to production of superhard materials.A carbon composition contains 18-38 wt. % of diamond having particle size of 40-120 .ANG. and graphite to make up 100 wt. % having particle size of 200-1000 .ANG..A process for producing the carbon composition consists in detonating a carbon-containing explosive having a negative oxygen balance, in a cooling medium containing 40-60 vol. % of carbon dioxide gas, not more than 2 vol. % of free oxygen, and a neutral gas to make up 100 vol. %.The present carbon composition will find predominant application as an abrasive for superfinish polishing.

Abstract: The vaulted building structure comprises a shell (1) made of a composite construction material and formed of arcuate elements (4) of a uniform width having their ends (5) mounted on a base (3). The shell (1) is shaped as a cylindrical vault of which the vertical axis of symmetry includes a vault ridge (2). The ends (5) of the arcuate elements (4) are hingedly braced to the base (3) for rotation about a horizontal axis parallel with the vertical plane of symmetry. The convex outer surface of each arcuate element (4) has its curvature gradually diminishing lengthwise of the arcuate element (4) towards its ends (5) and ridge (2) for levelling out strains generated in the shell (1) upon rotation of the ends (5) of the arcuate elements (4).