Abstract: The present invention provides: refractory composite materials protected against oxidation at high temperature; said materials are of the type made by a solid process and include, in characteristic manner, over their entire outside surface, a complex layer containing at least one silicate corresponding to a densification additive used to make them, silica, and a vitreous boron-containing silicate phase; precursors or intermediates for preparing said materials; said precursors including, in characteristic manner, over their entire outside surface, at least one layer of a precursor for borosilicate glass or a layer of borosilicate glass; and a method of preparing said materials (by preparing said precursors) and a method of preparing said precursors.

Abstract: The interphase is formed by nanometric scale sequencing of a plurality of different constituents including at least a first constituent that intrinsically presents a lamellar microtexture, and at least a second constituent that is suitable for protecting the first against oxidation. A plurality of elementary layers of a first constituent of lamellar microtexture, e.g. selected from pryolytic carbon, boron nitride, and BC.sub.3 are formed in alternation with one or more elementary layers of a second constituent having a function of providing protection against oxidation and selected, for example, from SiC, Si.sub.3 N.sub.4, SiB.sub.4, SiB.sub.6, and a codeposit of the elements Si, B, and C. The elementary layers of the interphase are preferably less than 10 nanometers thick and they are formed by chemical vapor infiltration or deposition in pulsed form.

Abstract: The pyrolytic carbon lamellar interphase is formed on the reinforcing fibers inside a chamber in which a plurality of successive cycles is performed, each cycle comprising: injecting a reaction gas in which the pyrolytic carbon precursor is selected from alkanes, excluding methane taken as a sole component, alkenes, alkynes, and aromatic hydrocarbons, and mixtures thereof; the gas is maintained inside the chamber for a first predetermined time period to form an interphase layer of controlled thickness of nanometer size; the gaseous reaction products are then evacuated during a second time period; the cycles being performed consecutively in the chamber until the thickness desired for the interphase has been obtained, thereby achieving a lamellar interphase that is highly anisotropic, whose lattice fringe texture has distorted fringes of total length (L.sub.2) not less than 4 nanometers on average with maximum values exceeding 10 nanometers.

Abstract: The pyrolytic carbon lamellar interphase is formed on the reinforcing fibers inside a chamber in which a plurality of successive cycles is performed, each cycle comprising: injecting a reaction gas in which the pyrolytic carbon precursor is selected from alkanes, excluding methane taken as a sole component, alkenes, alkynes, and aromatic hydrocarbons, and mixtures thereof; the gas is maintained inside the chamber for a first predetermined time period to form an interphase layer of controlled thickness of nanometer size; the gaseous reaction products are then evacuated during a second time period; the cycles being performed consecutively in the chamber until the thickness desired for the interphase has been obtained, thereby achieving a lamellar interphase that is highly anisotropic, whose lattice fringe texture has distorted fringes of total length (L.sub.2) not less than 4 nanometers on average with maximum values exceeding 10 nanometers.