Atochem

Annick Faure

Roland Bachelard

Jean Lesparre

Murielle Rabiller-Baudry

Roger Chevrel

Marcel Sergent

Ceramic preforms comprising monocrystalline hexagonal platelets of .alpha.-alumina, well adopted for conversion into refractory bricks or ceramic composites, are prepared by crystallizing a settled fine powder of amorphous alumina, transition alumina or alumina hydrate, advantageously in the presence of a fluoro-compound flux, into a coherent mass of such hexagonal platelets of .alpha.-alumina.

Ceramic preforms comprising monocrystalline hexagonal platelets of

Ceramic preforms comprising monocrystalline hexagonal platelets of .alpha.-

Macrocrystalline .alpha.-alumina hexagonal platelets, well adapted as reinforcing materials and polishing agents, are prepared by calcining admixture of transition or hydrated alumina and a fluorocompound flux, such fluorocompound flux having a melting point of up to 800.degree. C. and, in the molten state, serving to dissolve the transition/hydrated alumina.

Macrocrystalline .alpha.-alumina hexagonal platelets

Hydrocarbons are oxychlorinated by reaction with gaseous HCl and an oxygen-containing gas, in the presence of a catalytically effective amount of a ternary copper/molybdenum chalcogenide having the formula:

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Venissieux, France

Annick Faure