This invention relates to the impregnation of rigid porous articles, particularly metal castings. In its preferred form the impregnant is a liquid mixture of monofunctional (meth)acrylic ester and a relatively small proportion of polyfunctional (meth)acrylic ester to provide a cross linked product on curing and to facilitate washing of the casting with water and an emulsifier. A peroxy or other free radical catalyst such as AZBN is associated in the impregnant with an inhibitor such as a hydroqu...

The invention provides an in-line method of impregnating a porous article, particularly a metal casting, which comprises placing the article on a support, placing a cover thereover in sealing relation with support to define an impregnation chamber, applying a reduced pressure to the cover at the upper part thereof, admitting impregnant to the chamber until it at least covers the pores, allowing the pressure to rise to substantially atmospheric, removing excess impregnant from the chamber, and re...

A pressure vessel for use in impregnating porous articles comprising a support member for the articles, slidable between an upper position for degassing the articles and a lower position for impregnating the articles, a release mechanism operable from outside the pressure vessel to permit the support member to descend from the upper position to the lower position under gravity, and damping means at least partially within the pressure vessel for controlling descent of the support member.

A method of impregnating a porous article with impregnant to seal the pores thereof, which comprises placing the article in a vessel, evacuating the vessel to withdraw air from the pores, releasing the vacuum with the pores beneath the surface of a liquid impregnant in the vessel, removing excess impregnant from the vessel, washing excess impregnant from the surface of the article by supplying washing fluid to the vessel, removing the fluid from the vessel, heating the article while still within...

There is disclosed an article treating apparatus particularly apparatus for pressure-impregnating or vacuum impregnating porous articles such as metal castings. A holder for the articles or a metal basket containing them is disposed in an autoclave and can be rotated about a horizontal axis. It has a horizontal through-passageway so that articles to be treated can be simultaneously loaded at one end of the passageway and unloaded at the other end of the passageway by an indexing mechanism. The i...

An article handling apparatus including a holder into which an article can be lowered and from which it can be lifted and which can rotate the article about a substantially horizontal axis, the article including a projection on at least one side of the article, the holder including a member rotatable about the axis and having a radially outwardly open channel for receiving the projection when the article is lowered into position, in the channel in response to a predetermined rotary movement of t...

The sealing of small porous rigid articles by impregnation with a liquid synthetic resin impregnant and sequent curing of resin in the pores and provides a liquid (meth)acrylic ester impregnant composition comprising a free radical catalyst, an inhibitor and a higher alkyl (meth)acrylic ester and/or polyfunctional (meth)acrylic ester which has been obtained by transesterification in the presence of an organotitanium catalyst and from which the catalyst residue has not been removed. The catalyst ...

This circuit is a trunk type interface circuit which interfaces between duplicate copies of an ISDN system and T-carrier facilities. The circuit is controlled by a digital signal processor which has a 16-bit wide data bus. The digital signal processor is capable of supporting various Zero Byte Time Slot Interchange (ZBTSI) techniques. Also included is an administrative microprocessor which collects data concerning the operation of the trunk circuit and transmits this information to the ISDN syst...

A process for annealing crystal damage in ion implanted semiconductor devices in which the device is rapidly heated to a temperature between 450.degree. and 900.degree. C. and allowed to cool. It has been found that such heating of the device to these relatively low temperatures results in rapid annealing. In one application the device (17) may be heated on a graphite element (14) mounted between electrodes (15) in an inert atmosphere in a chamber (11). The process may be enhanced by the applica...

A system for, and a method of, detecting the proximity of a source of an alternating magnetic field, such as that emanating from power transmission cables, comprising a sensor coil sensitive to the magnetic field under detection, processing means to derive from the signal induced in the coil a warning signal indicative of the proximity of the magnetic field under detection, and cancelling means operable to cancel the earth's field in the region of the sensor coil. The sensor coil may be one of a...