US1800947A - Method of coating articles - Google Patents

Description

April 14, 1931. s R MASON 1,800,947.

METHOD OF COATING ARTICLES Filed Nov. 30, 1927 f/yi 5% //77 Patented Apr. 14, 1931 UNITED STATES PATENT. OFFICE BURNER MIDWAY MASON, 01' WILMETTIE, ILLINOIS, .ASSllGNOIB. "1'0 WE$TERN ELEC- "ERIC comm, INCORPORATED, NEW YORK, N. Y A CORPORATION OF NEW "YORK METHOD 0] COATIN' ARTICLES appumion fled November 30, 1927. Eerie! no. new.

placed on articles hy electrochemical means,

those portions of the articles which receive the most current, such as the edges, ends and protruding ortions, also receive the greatest to amount of the plated metal. This phenomenon is generally descrihed by saying that those portions of an article upon which the current density (usually expressed in sniper-es per unit urea) is highest obtain the m greutmt deposit end this phenomenon is somces spoken oi as the edge und/or'end eilect. Because. oi this tendency it is dimcult to obtain uniform deposits upon irregulur shaped ,ur'ticles especially when the plotso ing is heing done with a metal, such as chromium, which requires a. high current density tor its deposifion.

lit is the ohiect oi the present invention to provide u method at coating urticles by elecet tie-deposition in which the difiieulties result ing from edge and end effects are substantiolly eliminated and by means of which substuntiully uniform deposits of plated metals may he ohtained.

in accordance with the general features oi the invention, a piece of conducting metal is fined in contact with the end or edge of a.

part which it is desired to electroplate, and

the port and the afixed metal piece are contt nested as a cathode in an electroplating bath, the extremities of the ufirzed metal piece then torming the edgesund ends of the composite cutho-de end the edge end end sheets are disted. thereon. hitter deposit of the re thichuess hos heen produced, the com to cethode is disconnected end the shined motel piece muy rum-cu Kill l iii desired hum M l 0 H J v". 5.2. 1 e piloted port leuving the letter "Wltll e umrim motel costing thereon is believed thut the invention will he clearly understood from the following detailed descriptions of embodiments thereof taken in connection with the accompanyin drawing illustrating those embodiments, an in which Fig. 1 is a perspective view of a part to be coated;

Fig. 2 is a perspective view of the part shown in Fig. 1 partially surrounded by a.- mass of a conductive metal;

Fig. 3 is a vertical, longitudinal, sectional view of the composite article shown in Fig. 2 after a coating has been placed thereon;

Fig. 4 is a view similar to Fig. 3 illustrating the part shown in Fig. l with the finished coating thereon; v

Fig. 5 is a fragmentary, elevational view of a cylindrical part to be coated and a metal disk held thereon Toy Ia magnetic attraction;

Fig. 6 is u. longitudinal, sectional View of the ports shown in Fig. 6 with a coating thereon, and

Fig. 7 is a view similar to Fig. 6 with the metal dish removed from the coated part.

in practicing one method embodyin the invention, a part 10, such us shown in ig. 1 which is to {be plotted upon. its upper end lower surfaces with a uniform coating of a. metal such as chromium, is partially surroun ed es shown in Fig. 2 with a mass 11 of a conducting material, such as a low fusion point alloy, which may be molded there-T around. The mass of metal 11 is so formed as to completely surround the surfaces of the part 10 upon which no metal is to be deposited, while the upper and lower surfaces of the mum of metal 11 are substantially in the some planes us the correspondin sur- :hxccs oi" port l0 upon each of whidh it is desired to piece costing. The composite article produced by pertially surrounding the port Ittl "with the motel M is then comiected u in both of on clcctroplutcurrent densitye'at that the cell is adjusted to a value which 'ves a cathode current densit requisite for eposition of metal on the original part. The composite cathode is maintained in the electroplating cell until coatings 13 and 14 of the desired thickness have been deposited upon the original part when it is removed from the cell. X11 examination of the coated composite articles shows that the u per and lower surfaces of the part 10 have su bstantially uniform coatings 13 and 14 thereon, while the coatings uponthe edges of the metal 11, which edges now form the extremities of the composite article, are built up, as is shown at 16 and 17, due to the higher current density upon those edgeshe-coated composite article, such as is illustrated in Fig. 3, may find uses without further change, in which case the surrounding metal'is retained upon the original part 10 and the coated portions of the part may be employed for various purposes, such as for surface gauges. However, if it is desired to remove the surrounding metal this may be readily done either by manually forcing the part out of the surrounding metal or by melting the surroundin mass of metal,

.in which case the article wi look somewhat as is shown in Fig. 4 and will have uniform coatings upon its up er and lower surfaces.

In practicing anot er method embodying the invention, a cylindrical part 20 (Fig. 5)

composed of a magnetic material is ma' netized either temporarily or permanent y and a small disk 21 of a magnetic material is secured upon the end thereof by magnetic attraction. The composite article thus formed 1s lated in a manner similar to that described in the foregoing description, where- V upon a uniform coating, 22 will be deposited upon the part 20, whereas the-lower edge of thepart 21 will receive a greater deposit-,-

such as is shown at 24, due to the increased int. As in the method desc d herein fore, the aflixed metal part 22 with its irregular coating may .be retained upon the original part 20, if desired, or it may be removed by simply withdraw ng it against the force of magnetic attract1on,leavin the original cylindrical part 20 with a uni orm coating 22 thereon. ,If the finished coated part is a permanent magnet it may be used for many purposes in its magnetized state, but for most purposes it is advantageous to demagnetize the art'which may be accomplished by any suita le method well known in the art.

. methods of producing uniform coatings upon .articles included within the scope of the appended-claims. For example,- the auxiliary s pieces of conducting material are described p ece of metal from the part thereby eav- The methods described hereinbefore are merely convenient examples of embodiments ofithe invention and the invention is not limited to those embodiments, butembraces all ducting material be a metal for non-metallic conducting materials, such as carbon or graphite, also may be employed with satisfactory results.

In general terms, where the article'to be coated has a surface of moderate curvature such as the plane surface 10 or the cylindrical surface 20, terminating in a surfaceof relativelyw'sharp curvature such as an edge or corner, an auxiliary piece isattached to the article in such relation as to form a continuation of the surface of moderate curvature, ,thereby eliminating the ed in so far as the surfaceof m crate curvature is concerned and making it 'ble to-deposit a substantially uni orm coating thereon.

The methods embodying the invention ma be successfully practiced in connection wit the usual electroplating baths for the deposition of metals, such as copper, nickel, silver, etc., which reguire com aratively low cathode current ensities but the methods constituting the invention. are particularlg connection wit baths, such as those from or end eflect or their depositiom useful when practiced in.

which chromium may be deposited, which require 'a high cathode metal dc tion.

a whatis claimed is: I i p '1'. A method of roducing uniform coatings on articles, w 'ch consists in a piece of conducting material in contact with an article to be plated, connecting the resulting composite part as a cathode in an electroplating bath, maintaining the composite part therein until a coating of the desired thickness has been deposits inal article, and removing the piece of con ducting material from the part thereby leaving a substantially uniform coating upon the requiring hi h current densities for their deposition, w ich consists in afixing a piece of metal to an extremity of a part to be plated, connecting the resulting com ite articleas a cathode in an electroplating bathfadjusting the current to a va ue giving a current densityrequisite for deposition on the original part, depositing a coating of metal wu on the composite article, and removin the upon the origcurrent density for part. I 0

2. A method of coating articles with metals ing a substantially uniform coating upon the part.

3. A method of producin uniform coatings of chromium upon meta articles which ings on articles, which consists in surroundmg a portion of an article to be plated with a conducting metal, connecting the resulting composite part as a cathode in an'electroplat-' ing bath, maintaining the composite part therein until a coating of the desired thicknetic attraction a conducting member shaped to form a continuation of the surface of moderate curvature, connecting the resulting composite article as a cathode in an electro latmg bath, depositing a coatin of metal t ereon, and. removing the con ucting member from the article.

In witness whereof, I hereunto subscnbe y 1927.

- SUMNER REDWAY MASON.

name this 19th day of November, A.

ness has been deposited upon the exposed portion of the original article, and removing the surrounding metal from the article thereby leaving a substantially uniform coating upon the article. i

5. A method of producing uniform coatings on articles, which consists in molding a mass of a conducting metal around a portion of an article to be plated with a surface of the molded metal in the same plane as an exposed surface of the article to be plated, connecting the resulting composite part as a cathode in an electroplating bath, depositing a coating of metal upon the exposed surface of the original article, and removing the mass of conducting metal from the article thereby leaving a substantially uniform metallic coating upon the article.

6. A method of producing uniform coatings of chromium upon metal articles, which Y consists in surrounding a portion of an article to be plated with a conductive metal, connecting the resulting composite part as a cathode in a chromium plating cell, maintaining the composite parttherein until a chromium coatingof the desired thickness has been deposited upon the exposed portion of the original article, and removing the surrounding metal from the original article, thereby leaving a substantially uniform coating of chromium upon the article.

7. A method of coating an article having a surface of moderate curvature terminating in a surface of relatively sharp curvature, which consists in attaching to the article a conductinc; member shaped to form a continuation of the surface of moderate curvature, con- 7 necting the resulting composite article as a I cathode in an electroplating bath, depositing a coating of metal thereon, and removing the conducting member from the article.

8. A method of producing a uniform coating upon a surface of an article having a surface of moderate curvature terminating lg a surface of relatively sharp curvature, w

consists in attaching to the article by mg-

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