Eltech Systems Corporation

Jean-Pol Wiaux

Thinh Trong Nguyen

Christopher J Vance

Michel Chevigne

Dominique Darracq

A method is disclosed for manufacturing a reaction sintered composite article which comprises at least one ceramic component. The method comprises preparing a particulate mixture of precursor powders leading to the formation of said composite material upon reaction sintering, pressing said particulate mixture to a self-sustaining body, heating said body up to a temperature below the temperature at which the reaction sintering is initiated, comminuting the heat treating body, selecting particles of a suitable grain size distribution, pressing said particles into shapes of desired size and configuration, and heating said shapes up to a temperature at which the reaction sintering is initiated. The reaction sintered body comprises borides, carbides, nitrides or silicides of a transition metal of the groups IVb, Vb or VIb of the periodic table (comprising titanium, hafnium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten), and a metal oxide. In the case that the composite material comprises Al.sub.2 O.sub.3, TiB.sub.2 and facultatively Al, the precursor powder may comprise TiO.sub.2, B.sub.2 O.sub.3 and Al. Composite bodies of sizes, shapes, varying compositions or other particular configurations which do not allow for the preparation of the final bodies in one operation are produced by preparing sub-sections of precursor shapes which are pressed in a first pressing operation, assembled to a shape of essentially the final configuration, again pressed and reaction sintered.

Method for manufacturing a reaction-sintered metal/ceramic composite

Transition metals of the groups IVB, VB and VIB or alloys thereof with Al are electrodeposited in a system of an electrolyte based on an aromatic hydrocarbon. The electrolyte is originally prepared by dissolving 0.02 to 0.2 moles of an inexpensive high oxidation state transition metal halide and 0.2 to 0.5 moles AlBr.sub.3 in 1.00 mole of the aromatic hydrocarbon. Additions of transition metal powders or Mg or Al particles lead to the pre-reduction of the high oxidation state transition metal ions to lower oxidation states. Alkali metal or Mg halides may be used to establish favorable bath conditions. The electrolysis is carried out with dissolvable metal anodes, to maintain the bath composition. The plating current density, bath composition and method of preparation are chosen to obtain the desired composition of the coatings.

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Croix-de-Rozon, Switzerland

Jean-Pol Wiaux