GB839751A - Improvements relating to the manufacture of vitreous enamels - Google Patents

Abstract

839,751. Enamelling. CIANCHI, A. L. June 7, 1956 [March 7, 1955], No. 6656/55. Class 56. A method of making a vitreous enamel includes the step of delivering a finely-divided mixture or batch of the appropriate materials in a dispersed condition into a chamber in which the necessary high temperature is maintained so as to convert the mixture or batch wholly or partly into a glass. The glass is then disintegrated as by sudden cooling to produce the frit which is then ground or melted. The finely divided mixture 3 is allowed to fall from a hopper 2 through a sieve 4 into the top of a furnace 1 in the form of a shaft of refractory material, the sieve 4 being reciprocated as from an electric motor 5 dividing an eccentric 6 connected to the sieve. The upper part 1<SP>1</SP> of the shaft is conical, so that the mixture 3 only touches the walls thereof on entry, and is spaced slightly from a tapered lower part 1<SP>11</SP> leading to a funnel part 1<SP>111</SP> which delivers the treated mixture to a receptacle 7. which may contain water, a slide valve or damper 8 con-' trolling the exit of the material. The shaft 11 is heated to about 800‹C. to 1500‹C. by means of a jacket 9 having air and gas or oil blown into the bottom from a blower 10 and the product of combustion escaping through an opening 11 near the top. Openings 12 between the parts 1<SP>1</SP> and 1<SP>11</SP> allow for the ingress of air which passes up the shaft 1<SP>1</SP> and valves or dampers may be incorporated to control the air supply which may be preheated as by heat derived from the opening 11 of heating jacket 9. The lower part 1<SP>11</SP> is maintained at about 600‹C. to 800‹C. by means of an electric wire coil 8<SP>1</SP>. In place of liquid in receptacle 7, the hot glass may be pulverised by powerful jets of cold air. The funnel 1<SP>111</SP> and the top of receptacle 7 may be closed in by a chamber 14 and air sucked out or pumped in so as to accelerate or retard the downward movement of the particles of material. In a further construction (not shown) the particles fall through a straight shaft into a crucible heated by electricity to complete the conversion into glass, the crucible having an opening in the bottom through which the glass falls into the receptacle below. To ensure mixing of the constituents of the batch, water may be added so that the soluble constituents dissolve and form a coating over the non-soluble particles. The enamel is used as the dielectric of an electric capacitor or resistor. Specifications 693,461 and 716,259 are referred to.