A process for treating the surface of a die-cast article including the steps of chemically cleaning the surface, cleaning the surface with an argon plasma, depositing an ion vapor generated metallic coating, mechanically treating the deposited coating, and chromate converting the mechanically treated coating. Preferably, the die-cast metal article consists essentially of an aluminum or magnesium alloy while the metallic coating is aluminum. The mechanical treatment may be carried out by bead blasting, tumbling or barreling and may be followed by walnut shell polishing.

Apparatus for moving a reciprocating object, such as a spring biased poppet valve, between a rest and a second position. The apparatus includes two solenoids, each of which has a core, with one of the solenoids having a larger core and imparting greater force than the other. The solenoids are mounted in line with one another so that the core of one solenoid is adapted to contract the core of the other, with the latter being adapted to contact the object. A first solenoid provides a driving force to the object to move it in opposition to a biasing force and the second solenoid holds the object in its moved position when the first solenoid is de-energized. When the core of the first solenoid is in its rest position, it is out of contact with the core of the second solenoid and this enables the biasing force of the object to rapidly move to its rest position upon de-energization of the second solenoid.

In order to increase the performance of a mold of thermosetting resin, metal powder is dispersed in the resin mold which has a dense and voidless structure. The mold may be mounted on a back-up member of metal. In this case, the bonding between the mold and the back-up member is much assured when metal balls are contained in the mold near the back-up member. Furthermore, the mold may be electrically metal-plated. In this case, the mold is coated with a conductive plastic paint before being subjected to the electric metal plating in an electrolytic solution.

Disclosed is a direct drive servovalve having a molded plastic housing. A metal sleeve having a spool valve slidably disposed therein is placed within opposed cavities formed within opposite housing halves. The housing halves are brought together under pressure and an ultrasonic horn is activated. Energy directing beads formed on the housing halves as well as interfering surfaces about the periphery melt under a pressure and ultrasonic energy allowing the two housing halves to move toward each other and mate. Upon deactivation of the ultrasonic horn, the molten plastic material cools and forms a seal about flow ports in the metallic sleeve as well as a fusion bond about the periphery of the housing.

A mandrel is fitted with a molded sleeve of low-temperature alloy for forming a rigid bulge along the surface of the mandrel. The sleeve is shaped to define the. internal surface of the shell at the bulge. After the mandrel has been so modified with the low-temperature alloy sleeve, it is wrapped with composite cloth containing any thermosetting resin. These resins heat to a known temperature, and permanently set when cured at the set temperature. The curing temperature of the prepreg cloth composite material is lower than the melting point of the low temperature alloy. After curing, the temperature in the curing oven is raised above the cure temperature until it reaches the melting point of the low-temperature alloy, and the alloy liquifies and drains out the drain passageways provided in the mandrel without melting the thermoset resin binder in the fiber cloth as well as leaving the bulge formed by the composite cloth in the shell without obstructing the removal of the mandrel. The resulting composite tubular shaft is thus provided with a bulge of increased diameter. The shafts may be tapered on the external surface or they may have a varied internal diameter.