GB504016A - Improvements in means for allaying corrosion - Google Patents

Abstract

504,016. Spray - producers; ornamenting and bronzing. GILBERT, W.V. July 16, 1937, No. 19770. [Class 69 (iii)] [Also in Groups XV and XVI] To allay corrosion, decay, &c. of materials such as metals the surface thereof is treated by directing thereon a jet of gaseous fluid preferably moving at a high velocity and introducing in the jet an agent comprising a chromate or dichromate in powdered form. Fig. 1 shows a spray gun in which the agent is fed by means of pipe 17 and compressed air is admitted at 13 to impel the agent. An offshoot is provided to convey a stream of compressed air to the annular passage 20 so as to produce a spray as indicated. The keying or penetrating effect may be increased by the addition of sand &c. to the agent before, or during spraying. The agent may underlie or overlap another coating and, to this end, a spray gun having a number of barrels may be used. Fig. 2 shows a gun having two barrels - 22, 23 the first of which is adapted to spray a molten metal derived from the feeding of the wire 24 while the barrel 23 sprays the agent. The surface to be treated may be first prepared by sand blasting or applying a substance such as wax, pitch, resin, rubber, &c. or fusible powders blown through a flame on to a heated surface. The agent may be mixed with the compressed air prior to entry into the gun by means of the device shown in Fig. 3. Compressed air is admitted through the pipe 34 arranged tangentially stirring up the agent which impinges on the vanes 36 of the plate 33 which rotates violently and is forced upwardly against the spring 40 to uncover apertures 41 through which the admixed agent and compressed air pass through pipe 29 to the spray gun. Shield devices may be provided for the gun such as a flexible fabric 43 supported by a coiled spring 44 fitted on a housing 46 having a movable ball member 47 bored to receive the barrel 10 of the' spray gun. Suitable chromates for the treatment of metals include those of aluminium, bismuth, cadmium, calcium cobalt, iron &c., while for materials such as timber the chromates of ammonium, barium, copper, potassium, zinc, &c. are suitable. The agent may be heated either by a flame or in the spray gun. To produce a hard coating lead particles may be sprayed in conjunction with powdered glass and cobalt chromate through a flame. The spraying process may be carried out in three stages, the application of a suitable adhering substance, forcible projection of the agent and finally of say a paint for sealing or decorating purposes. In the case of fabrics or the like the requisite stream of air or gas can be produced by suction. Specifications 406,445, 422,860, [both in Group III], 428,375, [Group XXXVI], 432,831 ; and 441,126, [Group II], are referred to.