Abstract: A process for forming metal components of controlled porosity by welding, in which a predetermined amount of metal elements (50) of oblong shape is introduced into a mold (10) in which it is distributed isotropically. The metal elements are then subjected to increasing pressure (P) until the component has its final shape. The walls of the mold are then held in position and an electric current (I) flows through the metal elements and welds them together by local melting at the points of contact due to the Joule effect.

Abstract: The invention relates to a blade end for rotary wing of an aircraft, whose span is between 5 and 15% of the span of said blade. According to the invention, this blade end is charaterized in that, between points A and B', there is a stagger which, measured parallel to the span of the blade, is between 5 and 25% of the chord of the profile of the blade adjacent said blade end and in that the leading edge line of said blade end is curvilinear and such that its angle of sweep .phi. varies progressively and continuously from a low value .phi..sub.o near the blade, of between 0.degree. and 30.degree., up to a high value .phi..sub.E towards the outside of the blade, of between 60.degree. and 90.degree.. The invention leads to increased performances and to a reduction in the noise level of rotary wings.

Abstract: Apparatus for dry chemical etching caused by ion bombardment of a substrate placed in a vacuum chamber. The substrate is in contact with an electrode, connected to a high frequency bias voltage source having one terminal connected to a ground of the chamber. The etchants are produced in the form of plasma by an electrical discharge maintained in the chamber containing a gas or a suitable gaseous mixture. The plasma is produced by a microwave generator and the bias voltage by means of a high frequency source. The respective amplitudes and frequencies of the two sources enable the base of a groove on an electronic circuit to be etched without erosion of the groove.