US 3787191 A
Electroplating a metal surface which has previously been, or is thereafter peened with high velocity, microscopic, spherical glass bodies to produce microscopic craters thereon, and optionally, removing a portion of the plating so peened by dissolving same with acid. By plating an already peened surface with a reflective material, the zone and/or intensity of reflectivity of the plated surface is increased and/or controlled.
Claims available in
Description (OCR text may contain errors)
United States Patent [191  3,787,191 Duncan Jan. 22, 1974 METHOD OF PRODUCING REFLECTIVE 3,382,159 5/1968 Reed 204 29 SURFACES AND ARTICLE 2,516,986 4/1950 Heinse.... 204/29 2,177,572 10/1939 Kogcl 117/8  Inventor: Leon L. Duncan, 811 Duncan Ave.,
Washington, Mo. 63090 22 d: M 0 3 1971 Primary Examiner-John H. Mack 1 1c M Assistant Examiner-W. lv Solomon 1 1 pp 120,663 Attorney, Agent, or Firm-Mason, Mason & Albright Related US. Application Data  Continuation-impart of Ser. No. 840,442, July 9, 1969, abandoned, which is a continuation-in-part of Ser. NO. 804,364, Feb. 25, 1969, Pat. N0. 3,545,996,  ABSTRACT which is a continuation of Ser. No. 332,230, Dec. 20, l963,abandoned. Electroplating a metal surface which has previously been, or is thereafter peened with high velocity, mi-  US. Cl 29/191, 72/53, ll7/8, croscopic, spherical glass bodies to produce microll7/35 R, 204/19, 204/29, 204/35 R scopic craters thereon, and optionally, removing a  Int. Cl C23b 5/48 portion of the plating so peened by dissolving same  Field of Search 51/319; 72/53; 117/8, 35 R; with acid. By plating an already peened surface with a 204/7, 19, 29, 36, 35 R; 29/191 reflective material, the zone and/or intensity of reflectivity of the plated surface is increased and/or con-  References Cited trolled.
UNlTED STATES PATENTS 3,019,522 2/1962 Bluth et al. 72/53 10 Claims, 5 Drawing Figures Pmmwme 3.787. 191
/N VE N TOR LEON L. DUNCAN BY Wm, WM
METHOD OF PRODUCING REFLECTIVE SURFACES AND ARTICLE CROSS-REFERENCES TO RELATED APPLICATIONS This is a continuation-in-part application of patent application Ser. No. 840,442, filed July 9, 1969 and now abandoned, which is a continuation-in-part of patent application Ser. No. 804,364 filed Feb. 25, 1969, now Pat. No. 3,545,996 issued Dec. 8, 1970, which was a streamlined continuation of application Ser. No. 332,230 filed Dec. 20, 1963 and now abandoned.
BACKGROUND OF THE INVENTION This invention relates to a process for producing a distinctive plated surface by the peening of such surface with microscopic spherical bodies either before or after the plating process or both to produce a surface having special decorative and/or reflectivity characteristics.
Electroplating is generally used for ornamental purposes where the color and luster are principal factors or to provide resistance to tarnish or corrosion of the underlying or base metal or both. The ability of any metal coating to protect the underlying coating against corrosion is determined primarily by its position in the electrochemical series, by its ability to adhere closely to the base metal, and in particular for metal coatings lower in the electrochemical series than the metals they protect, by the porosity or permeability of the coating. Because of its position in the electrochemical series, zinc is preferred as a coating for iron or steel which may be exposed outdoors to corrosion and, in fact, appreciable areas of iron may be exposed without rusting provided a zinc coating is adjacent the iron. Unfortunately, zinc coatings do not possess or retain a pleasing appearance, and in consequence for many purposes they are not acceptable. Although various methods have been suggested to secure the protective value of zinc in a more ornamental finish, these frequently add substantially to the overall cost and at the same time reduce the protective value of the zinc coating. In general, therefore, the maximum protective value of zinc is afforded when it is applied directly to the iron or steel and it is not coated with any other metal.
Where nickel, lead or copper are deposited on iron, the value of the deposit depends largely upon its freedom from pinholes or porosity. Nickel coatings having adequate impermeability for a minimum thickness are generally highly reflective. In any event, it should be appreciated that electrocoating techniques have certain inherent limitations which relate to the effectiveness of a given coating vis-a-vis its appearance.
I Often the reflectivity of a surface is an important consideration for various uses. Surfaces, such as stainless steel, which have been treated by peening same with microscopic spherical bodies, have a satin-like finish and it has been determined that such surfaces have special utility where the characteristic of reflectivity is important such as in the case of traffic signs and daylight screens for slide and motion picture images. However, to obtain the desired reflectivity of surfaces through this means, the treatment must be closely controlled and, even so, limitations exist as to the characteristics of the reflectivity so obtained.
SUMMARY OF THE INVENTION The invention is basically directed to the treating of surfaces to be plated by peening them with microscopic spherical bodies which serves the double purpose of removing grease and other unwanted substances from the base metal, and to give the surface selected for plating a unique reflectivity characteristic. Microscopically, the surface has generally uniformly sized craters. This effect is somewhat accentuated and the reflectivity characteristics are controllable within limits by the plating since there is a tendency for the plating metal to accumulate somewhat more thickly on the edges or rims of the microscopic craters. If desired, after the electroplating process, the surface can again be peened by microscopic spherical bodies to improve the adhesion. This step can also be carried out even though the plated surface was not initially so peened. In either case, depending upon the thickness of the plating, the underlying metal may be exposed by the peening process which provides an unusual ornamental effect. By thereafter dissolving a portion of the deposited plating a still further distinctive appearance is possible. The peening treatment may be effected through stencils in order to confine the unique surface areas produced in accordance with this invention to limited areas or ornamental or functional purposes.
Other objects, adaptabilities and capabilities will appear as the description progresses, reference being had to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a section in magnification of a plated surface subjected to the process of the invention;
FIG. 2 is similar to FIG. 1 showing the same section following removal of metal by acid;
FIG. 3 is a section in magnification of a steel surface which was initially peened and thereafter electroplated with zinc;
FIG. 4 shows a similar magnification of zinc electroplated to a steel base which was thereafter subjected to a peening process; and
FIG. 5 is a further section in magnification of a steel surface which was initially peened and thereafter electroplated to produce a chrome surface having an increased angle of reflectivity.
DESCRIPTION OF PREFERRED EMBODIMENTS Methods and apparatus for peening with microscopic beads are disclosed in my parent application Ser. No. 804,364, now Pat. No. 3,545,996. Similar types apparatus are also disclosed in U.S. Pat. Nos. 3,186,132, 3,305,916, and 3,407,719. Such treatment has been known and enjoyed with acceptance in the last several years particularly since the advent of dry glass bead peening and reclaim systems which effectively separate the blasting particles from the dust debris arising from blasting operations. The glass beads utilized in the process range in size between 0.005 and 0.026 inches in diameter with diameters of 0.0035 0.0059 inches being used for most applications. The glass bead particles are brought to impinge upon the metal being treated at a high velocity so as to create the crater effect on such metal surface. The surface is thus effectively cleaned from grease and other adherents and at the same time is worked and thus, if steel, somewhat hardened.
In electroplating, the average thickness of the satisfactory commercial nickel coating on an article is rarely over 0.0002 inches and is usually less than 0.0001 inch. On the other hand, a good zinc coating is almost always at least 0.0005 inches and frequently over 0.001 inches in thickness.
It has been ascertained that interesting and novel effects may be achieved by combining the plating and peening operations, the plating taking place either before or after the peening operation. For example, FIG. 1 shows a magnifying section of copper electroplated on an aluminum base 9 to a thickness of about 0.002 inches. It will be noted that the peening creates thickened rims l and craters 11. The aluminum may be exposed in the pits of the craters to give a contrasting effect. This effect may be heightened by dissolving a portion of the copper in an acid bath to afford a surface such as shown in FIG. 2 wherein only copper may be found in the rim areas 10.
When the plating is accomplished following the peening treatment, the surface retains its satin-like appearance, particularly with thin gauge plating, and the bond of the plating on the surface is substantially improved. FIG. 3 shows an example of an electroplating of zinc 12 on a steel base 14. The average thickness of the zinc deposit is about 0.001 and relatively large glass bead particles were utilized in the peening operation. It will be noted that the zinc coating 12 is thicker in the rim areas 15 than in the craters 16.
In FIG. 4, the base metal 17 is again steel and the electrocoating 18, zinc. The surface has been treated after the plating operation with relatively large sized glass bead particles to produce craters 20 surrounded by rims 21. At places the underlying steel is exposed and the thickness of the zinc in the rim areas 21 is substantially greater than the average thickness of the zinc deposit. The adhesion of the coating is improved. Also, since most articles which would tend to scratch or otherwise mar the surface tend to ride on tops of the craters 21, the plated article is more resistant against damage of this nature.
In FIG. 5, the base metal 22 is steel and three electrocoatings, copper 24, nickel 25 and chromium 23, have been applied successively thereto. The surface of metal 22 is first treated to produce a plurality of microscopic generally uniform shallow craters 26 which include rim areas 27 and lower portions 28. It will be noted that the rim areas 27 have a substantially thicker plating than plating at the bottom portions 28 and that the depths of the craters are increased by the plating. In other words, the craters 26 are, prior to the plating operation, shallower than after such operation. Because of this, the angle of reflectivity of light from a single source impinging on the plated surface is increased compared to that which exists due to the microscopic surface contours prior to the plating operation. By controlling the plating, the angle of effective reflectivity can be controlled within limits. This is important with traffic signs intended to reflect automobile headlights at night and daylight type projection screens. An important advantage is that reflective surfaces, in accordance with the invention, are relatively inexpensive to produce compared to present methods for producing comparable products.
Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:
1. A method of treating a metallic surface which comprises the separate steps of first electroplating said surface with a further metal and then peening said surface through said plating by directing microscopic substantially particulate spherical peening bodies entrained in a gaseous fluid at said surface with sufficient velocity whereby microscopic craters are created in both said surface and said plating with said craters having thickened rims of the plating material.
2. A method in accordance with claim 1 wherein the first step comprises electroplating a metal having a higher negative potential in the electromotive series than metal on which it is plated.
3. A method in accordance with claim 1 wherein said first step comprises electroplating zinc on a steel surqc- 4. A method in accordance with claim 2 wherein the particulate peening bodies are between 0.005 and 0.03 inches in diameter and the zinc coating is at least 0.0005 inches thick.
5. A method of treating a metallic surface which comprises the separate steps of first peening said surface with microscopic substantially particulate spherical peening bodies entrained in a gaseous fluid having a velocity of at least 2,600 feet per minute directed at said surface whereby microscopic craters are created in said surface and then electroplating said surface with a further metal substantially thicker on the rims of said qayaslm mh p 0f a qs.
6. A method of producing a reflective metallic surface which comprises the steps of first peening said surface with microscopic substantially particulate spherical peening bodies entrained in a gaseous fluid having a velocity of at least 2,600 feet per minute directed at said surface, to produce continuous microscopic craters on said surface and then plating said surface with a reflective metal substantially more thickly on the rims than in the lower portions of said craters whereby the depths of said craters from their lower portions to their rims are increased and the angle of reflectivity of said Surface sinw aislw W.
7. A method in accordance with claim 6 wherein said plated surface isaplated chron surface.
8. An electroplated article having a novel metallic surface, said article comprising a base metal and a further metal electroplated thereon, said base metal having microscopic craters, said electroplating extending over said base metal including the rims and at least in part over the lower portions of said microscopic craters, said plating being substantially thicker on the rims of said craters than in the lower portions of said craters.
9. The article of claim 8 wherein said base metal is exposed in the bottoms of said microscopic craters.
10. The article of claim 8 wherein said metallic surface produced by said electroplating has a greater angle of reflectivity than that of the base metal prior to being electroplated.