GB367074A - Improvements in and relating to the coating of materials - Google Patents

Abstract

367,074. Coating articles by electric discharge. KNOLL, M., 23, Steinmetzstrasse, Lichterfelde, Berlin. Dec. 4, 1930, No. 36631. [Class 41.] In depositing metals or other substances by cathode dispersion in a vacuum on materials such as paper, celluloid, cellon, cellophane, and insulating and textile materials which give off gases, these are diluted by introduction of an inert or reducing gas such as nitrogen or hydrogen while maintaining the vacuum. In the apparatus shown in Fig. 1, the container 5, exhausted through a pipe 19, is provided with a side chamber for the reception of a drum 16 of fabric which is unwound through a slot 29 over a cylindrical support 9 on to a drum 18 in a second side chamber 15. The chamber 14 is independently exhausted through a pipe 27. The negative electrodes 13 are in the form of thin tubes of steel or bronze, provided with end sockets 40, Fig. 3, connected to a cooling water system. The sockets 40 are secured with insulating plates 43 in tubular fittings 47, 48, mounted in the end walls 7, 6. The fitting 48 is joined to a tubular member 49 secured in the wall 6 by a corrugated pipe 50 and is adjusted in order to tension the electrode by a nut 51 engaging a projection 53. Rotation of the part 48 is prevented by engagement of the projection 53 with a slot 52 in the member 49. The material to be dispersed may. be applied to the electrodes mechanically or galvanically. Current is supplied by a transformer 23 and rectifying tube 24. Deposition of electrode material on the container 5 is prevented by means of a screen 35 which is maintained at a negative potential by glow discharge or by connection to a potentiometer 38. Connection may be made by a wire 37 fused into a glass body 36 pressed by a cap nut and packing rings against the container. Nitrogen is admitted to the container by a valve 20 automatically controlled through a relay by the discharge current. The fabric may be drawn through the apparatus in stages, deposition taking place while it is stationary. A pattern may be deposited by the use of a screen 39 which is raised automatically during passage of the fabric. Patterns may also be imposed by the periodic switching in of electrodes of different materials e.g. gold and silver and by the use of electrodes composed of different materials throughout their length. The cylinder 19 may be supported by a carriage mounted on rails 10 and inserted through an opening in the end wall provided with a gastight cover. The opposite end wall may also be provided with an opening and cover. The deposit may be observed by means of a lamp 30 and window 31 and its thickness determined by measurement of the resistance between brushes 32, 33.