Abstract: The invention relates to a method of manufacture of a multilayer ceramic shell mould whereof at least one contact layer out of a wax master pattern or a part to be manufactured, or other similar material, consisting in dipping the master pattern in a first slip containing ceramic particles and a binder, in order to form said contact layer, in depositing the sable particles onto said layer and in drying said contact layer. The method is characterised in that the ceramic particles of the slip are mullite particles.

Abstract: The invention proposes a method for passivating the contact surface of a refractory container made of mullite. Such a method is remarkable in that it comprises the following operations: a. application to the contact surface of a coating comprising 50% to 70% by weight of alumina flour (Al2O3) filler and 30% to 50% of binder, this binder itself comprising 50% to 60% of aluminum chloride AlCl3 dissolved in 40% to 50% of water; b. drying; c. firing of the container in an oxidizing atmosphere between 1450° C. and 1550° C. for at least 20 min. Application to the casting of titanium alloys.

Abstract: This invention relates to an electric switch intended to be placed in an electric power circuit, said switch being responsive to a control signal. The switch comprises a semiconductor switch, an electromechanical switch and a signal processor. The electromechanical switch is connected in parallel to the semiconductor switch. The signal processor receives the control signal and outputs a command signal for controlling the semiconductor switch and the electromechanical switch. The invention also relates to a process for switching an electric power circuit.

Abstract: A method of making a ceramic shell mould for casting includes making a pattern having an internal cavity in two parts from a disposable material, glueing the two parts together to complete the hollow pattern, filling the internal cavity with a ceramic material, and simultaneously or subsequently forming a shell of a ceramic material around the filled pattern. The pattern can then be eliminated to obtain a casting mould with an inner core made in situ.

Abstract: A method of making a complex ceramic core for use in a metal casting process of the lost wax type, the core having at least one recess which extends into the interior of the core and being intended for use in the manufacture of a hollow component having internal cavities and partitions, including successive and superimposed injections of at least two compounds, one of which is degradable without harming the other(s), in at least one mold to produce a solid body wherein the other(s) of the compounds forms said core and the degradable compound fills the recesses of the core. The first injection creates a blank from one or other of the compounds, and each successive injection forms a layer which covers, at least partly, the outer surface of the blank obtained after the preceding injection until the solid body is completed. The body is then treated to remove the degradable compound and thereby leave the desired complex core.

Abstract: A method of making a shell mould, particularly for a lost wax casting operation, includes the deposition of an adhesion agent on the pattern before the deposition of layers of ceramic material to build up the mould. The adhesion agent used is preferably a 3% solution of aminosilane in a solvent consisting of ethanol and ethyl acetate in amounts from 25% to 75% of the solvent. The method avoids the phenomenon of detachment at the pattern/ceramic interface.