US1417413A

US1417413A - Coloration of metallic surfaces

Info

Publication number: US1417413A
Application number: US393198A
Authority: US
Inventors: Rondelli Tito; Sestini Quirino
Original assignee: SESTRON FOREIGN PATENTS Ltd
Current assignee: SESTRON (FOREIGN PATENTS) Ltd; SESTRON FOREIGN PATENTS Ltd
Priority date: 1920-06-30
Filing date: 1920-06-30
Publication date: 1922-05-23
Anticipated expiration: 1939-05-23

Description

Italy, residing at Turin UNITED s'rA'ras PATENT 'rrro RONDELLI, or runm,ann eumino sns'rmr, or ammo,- ITALY, assron'oas or onn-rnmn 'ro snsrnon (FOREIGN PATENTS) LIMITED, or LONDON, rum

LAND.

comm'rron or METALLIC sunraons.

No Drawing.

To all whom it may concern:

Be it known that we, Trro RQNDELLI and QUIRINO Snsrmr, subjects of the Kin of Italy, and er'-' game, Italy, respectively, have lnvented certain new and useful Improvements in the Coloration of Metallic Surfaces, (for which on October 27, 1916, we filed an application No. 156,509 for Letters Patent of Italy), ofwhich the following is a specification.

This invention relates to the coloration of metallic surfaces, and has for its object to provide an improved process for this purose. p In the prior British specification, No. 106774 (No. 16582/16) a process for bronzing or colouring metallic surfaces is described according to which the surface to be bronzed or coloured is electrolytically coated with copper from an electrolyte which is ahot dense alkaline solution, (for example, having a temperature of v about 120140 C and adensity about 1.3-1.5)

containing an oxide of copper combined.

with the alkali, and the surface is then coloured or bronzed, for example, by anodic oxidation in the electrolytic bath. It has now been found that a modification of this process is specially adaptable for the coloration of metallic surfaces, such as copper and ferrous surfaces.

According to the present invention the improved process for colouring metallic surfaces consists in immersing the object, the surface of which is to be coloured, in a warm or hot electrol ic bath containing a Kfixed alkali in which 1s dissolved, preferably to saturation or substantially so, a compound of copper, for example, oupric oxide or hydrate, the object under treatment being made to serve exclusively as anode for a. shorter or longer period.

a The copper bath may be prepared in any suitable way by chemlcal or GlBCtI'O-ChBlllb 1920. Serial No. 393,198.

preferably is such that the solution boils at a comparatively high temperature, for,

example 120150 C. A wide range of cur- Patented May as, recap rent density is applicable, for instance,

from 1-30 amperes per square decimeter of the surface to be coloured, the particular density employed depending, of course, upon the circumstances of the case. For certain copper alloys it will be found that a comparatively low current density should be used, such as one from 3-5 amperes per s uare decimeter, while in other cases, as w en the surface under treatment consists ofsubstantially pure copper or of bronze of-high copper content, a density of from l0-12 amperes may be conveniently employed. As will be readily understood, the conditions in any given case will be de termined'b the nature of the surface to be coloure the object and the particular effect desired. The same considerations apply to the "tem perature and to the time during which the object is immersed. When copper alloys are in question the concentration of the bath as well as by the nature of and the temperature depend in particular upon the constitution of the alloy. In every case, however, a simple preliminary experiment sufiices to determine the most ad-' vantageous conditions necessary to obtain the result desired. By varyin the conditions different effects, from fight green and dark blue colours through darker colorations u to black, may be produced, I

.The f0 lowing'examples will serve to indicate the character of the invention in more detail, but it is to be understood that these examples are given as illustrative only and not by wayof limitation.

Example 'I. v Copper oxide is dissolved to saturation'in a solution of caustic soda which boils bea 'duced.

sistant to corrosive agencies and can be .pol-

the anode in the same bath as in Example 1,. under current density of 5 amperes per square decimeter, the temperature being 75 and the time of immersion about 2 minutes. A similar result is obtained as in the previous case;- If the treatment be applied only for afew seconds iridescent effects are pro- Ewample 111. An.iron object is immersed in the same 'bath as in the previous examples, the temperature being between 90-1309; and is subsulphides or sulphides of alkali earths, and

mitted to anodic-oxidation under a current density not exceeding 5 amperes per square decimeter. After about 5-20 minutes treatment, according to the constitution of the iron, and-the condition of the surface, the latter is coloured a deep blue black.

Not infrequently, copper and copper alloy surfaces are coloured by deposition thereon of arsenic, or even, in some cases, of platinum, bfut coloration is more generally effected by treatment in solutions of alkali it. has also been the practice to employ a solution of copper nitrate, or of copper. carbonatein ammonia. The three first processes, however, do not give satisfactory results either in respect to the colour produced, or to its: permanence, while the last two methods are not easy of application, and regular effects are difficult to obtain. The present invention provides a simple and expeditious means of colouring metallic surfaces, and of obtaining varied effects with facility and regularity.

A process for oxidizing ferrous surfaces by treating the same without the use of an electric current in an alkaline bath containing the oxide of a metal which behaves electro-negatively towards iron is described and. claimed in our co-pending application Serial No. 393,199, filed June 30, 1920.

What we claim as our invent-ion and desire to secure by Letters Patent is 1. The process for colouring metallic surfaces which comprises submitting the surface to be coloured to anodic oxidation in the presence of a. concentrated alkaline electrolyte containing copper.

2. The process for colouring metallic surfaces which comprises immersing the object the surface of which is to be coloured in a concentrated solution of fixed alkali in which is dissolved a compound of copper and submitting the surface to anodic oxidation.

. 3. The process for colouring metallic surfaces which comprises immersing the object the surface of which is to be coloured in a concentrated solution'of fixed alkali in which is dissolved a compound of copper and submitting the surface to anodic oxidation with application of heat.

4. The process for colouring metallic surfaceswhich comprises immersing the objectthe surface of which is to be coloured in a concentrated solution of fixed alkali in which is dissolved to saturation a. compound of copper and submitting the surface toanodic oxldation. A y

5. The p-rocessfor colouring metallic surfaces which comprises immersing the object the surface of which is to be coloured in a solution offixed alkali of a densit of 1.3-1.5 in which is dissolved a compound and submitting the surface toanodic oxida- 6. The process for colouring metallic surof copper faces which comprises immersing the object v the surface of which is to be coloured in a solution'of caustic alkali of a density of 1.3-1.5 in which is dissolved a compound of copper and submitting the surfacetoanodic oxidation. p

7; The process for colouring metallic surfaces which comprises immersing the object the surface of which is to be coloured in a solution of caustic soda of a density of 1.3-1.5 in which copper oxide is dissolved to saturation and submitting the surface to anodic oxidation.

'8. The process for colouring metallic surfaces which comprises immersing the object the surface of Which is to be coloured in a.

solution of caustic soda of a density of 1.3-1.5 in which copper oxide is dissolved to saturation and submitting the surface to anodic oxidation with application of heat.

9. The process for colouring a copper. surface which comprises immersing the object the surface of which is to be coloured in a concentrated solution of fixed alkali in which is dissolved a compound of copper and submitting the surface to anodic oxidation.

10. The process for colouring a copper S111. face which comprises immersing the object the surface of which is to be coloured in a solution of caustic soda, having a boilingpoint between about 120130, in which copper oxide is dissolved to saturation and submitting the surface to anodic oxidation with application of heat.

In testimony whereof we have signed our names to this specification in the presence of twosubscribing witnesses.

1 TITO RO-NDELLI.

QUIRINOv SES-TINI.

Witnesses to signature of Trro RoNDELLI:

J. PHILLIPS CRAWLEY, J. W. PATCHING. Witnesses to signature of QUIRINO Snsrrm:

DANTE DANIELE, Anselmo Vnm',