JPS63195295A - Method for forming decorative coating on metal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to decorative coatings on metal, in particular for the decorative industry, crafts, furniture manufacturing, veneers and coin casting, metal plastic workpieces and medals. The present invention relates to a method for producing decorative coatings on aluminum, titanium, niobium, zirconium, tantalum and other alloys.

A multistep process involving surface roughening, texturing, emulsion application, coloring, and sealing is currently used to deposit matte, matte surface layers on relatively inexpensive and easily machined metals. .

On metals commonly used in the ornamental or jewelry industry, such as silver, gold, platinum, such matte coatings cannot be obtained directly, but indirectly through organic or inorganic coating layers. It will be done. However, these coating layers optically reduce the value of the expensive precious metal bullion. A known method for producing decorative and colored metal surfaces is the Calcolor method or colored anodization method (US Pat. No. 3,631,383). In this case, the color is generated directly by the electrolyte, or organic colorants or inorganic pigments are subsequently introduced into the transparent carrier layer for coloring. This carrier layer can be, for example, aluminum, sulfur electrolyte, phosphorus electrolyte,
Produced by direct or alternating current anodization in maleic or salicyl-oxalic acid electrolytes. However, such surfaces always exhibit a "cold" shine. In this relatively expensive multi-step process, homogeneous surface decoration of plastics, medals, wood, delicate structures, brooches, etc. is not possible or is only possible with high technical costs. Furthermore, transparent layers of aluminum oxide produced by anodizing aluminum are also known, which can then be colored with various colorants (US Pat. No. 3,031,387).
. Since these layers are transparent, they retain the metallic luster of the surface. Also, the organic substances used for the coloring of this layer are influenced by environmental effects such as light, temperature and humidity and change their color tone.

Furthermore, various decorative metal surfaces are known in the decorative industry. For example, in East German Patent No. 204,845 a method is described for using electronic packaging as decoration. DE 14 46 289 proposes an enameling method for decorative coatings on decorative articles. Colored anodized aluminum parts are also used as decorations.

[Object and effect of the invention]

The basic object of the invention is to produce an optically attractive, decorative, glossy, white, black or other colored layer with a high degree of dimensional accuracy, adhesion and color uniformity all over. A method for fabricating on aluminum, titanium, niobium, zirconium, tantalum and alloys is provided.

[Summary of the invention]

According to the present invention, in the aqueous electrolyte, the barrier layer forming metals, aluminum, titanium, tantalum, zirconium,
On niobium or its alloys, the electrochemical reaction determined by the pulse voltage and the plasma chemical reaction: Voltage peak of 250 V to 750 V, Pulse time of 20 μs to 2 ms, Pulse frequency of 35 Hz to 300 Hz, Pulse frequency of 10 A to 1
A pulse current amount of 20 A, an electrolyte temperature of 318 to 360, and 0, l
The above-mentioned problem is solved by obtaining a matte decorative layer with a uniform thickness of 3 .mu.m to 30 .mu.m and a precise contour under the condition of an average current density of Acm-2 to IAcai-2.

The voltage values mentioned are in the arcing region of the current-voltage characteristics of the electrolyte-metal pair and would normally lead to layer destruction, but in pulsed operation up to 300 Hz they lead to the formation of a homogeneous layer over the entire surface. was discovered.

Particularly due to the pulsing action, which has needlepoint characteristics, the partial anode area is significantly reduced and the energy introduction into the underlying layer is very localized, so that the individual earth spots strongly overlap and are evenly distributed with less roughness. It was shown that a layer with a certain thickness was formed. Furthermore, the pulsed operation according to the invention makes it possible to construct colored layers with excellent quality and color strength even in electrolytes containing high concentrations (up to 20%) of transition metals.

Also, the temperature of the electrolyte containing the coloring additive between 318 and 360C promotes the coloring of the layer, and the temperature between 0. IA~1. OA
It has been found that an average current density of cm@-2 produces a particularly matte surface. Furthermore, it is surprising that during pulsed voltage operation on aluminum, for example using an electrolyte containing cobalt ions, the known black-gray deposits of cobalt oxide compounds on the aluminum surface do not occur.
A matte blue cobalt-aluminum-spinel metal coating is obtained which is of high optical and mechanical value.

Thus, at the same concentration of 1% to 20% in the electrolyte, copper ions have a pale yellow to ocher layer, manganese ions a rose to amber layer, chromium ions a green to black layer, iron Ions form a light gray to dark black layer, and molybdenum ions form a light gray to dark gray layer.

The layer produced by the method of the invention has a thickness of 4 μm to 20 μm.
It has an average surface roughness of μm and consists of layers in two different regions. The layer area adjacent to the metal surface is transparent to white and has a thickness of 0.1 μm to 1.5 μm. The coating layer region connected to this transparent to white layer region is white, black, colored matte, or opaque, and has a thickness of 3 μm to 25 μm.
It has a thickness of μm. With a maximum thickness according to the invention of 30 μm, there is a transition zone between the transparent to white layer area and the covering layer area.

The transparent to white layer region does not contain colored transition metal ions and acts as an adhesive medium for the covering layer region.

Since the lattice parameter deviation of the metal with respect to the transparent layer region is minute due to the electric field crystallization effect, no mechanical stress occurs at the interface between the metal and the metal oxide in the transparent or white layer region. Furthermore, since the transparent to white layer region and the covering layer region are composed of the same basic metal oxide, despite the lattice expansion of the oxide inside the covering layer region, both are conditioned by the charged transition metal ions. A high degree of bond stability is ensured between the oxide layers. The color in the coating layer area is determined by the loading of transition metal ions. With these inorganic colorants there is no risk of fading.

A light-resistant spinel or mixed oxide is produced.

Several different anodizations according to the invention in different electrolytes result in the formation of several different coating layer areas, so that a homogeneous and/or heterogeneous color distribution results. The matte appearance of this decorative coating is characterized by its very low gloss. Gloss measurement by the Richter method showed a glossiness of 0.5 to 1.5, independent of the reflection angle. This means a completely matte surface. Various concentrations of transition metal ions up to 20% in the coating layer area gave shading combined with a uniform or marble-like pattern, or flecks, or flame pattern, or mosaic appearance. The metal surface can be provided entirely or partially with an anodic oxide layer. By combining surface areas with colored coatings, transparent coatings and/or interference color coatings and/or other conventional anodic coatings, a wide variety of expressions can be obtained.

The ornaments treated by the method of the invention are easy to wear on the body because the chemically unreactive oxide layer prevents direct contact of the metal with the skin.

(Examples) The present invention will be explained in detail below using examples.

Example 1 Titanium cufflinks were treated with 0 #1 mol/I Na B
It was connected as an anode in an electrolyte containing O and 0.5 mol/1 KH2PO4 and provided with a deep red characteristic oxide layer by a voltage of 60 volts. Cover half of each button with a protector, 0.5 mol/1 NaF, 0.3
mol/g NaHPOo, 1 mol/II Na2B4O
7 and 0.5 mol/II of K (F e (CN) a
) in an aqueous electrolyte with a composition of
, with a pulsed current density of IA/el12 and a time of 60 seconds. A combination of a unique layer of deep red interference color and a deep black matte oxide ceramic layer was obtained.

Example 2 An aluminum alloy replica of an antique (boatlet)
0.5 mol/1 NaF, 0.5 mol/fl NaH2
Anodization was carried out in an aqueous electrolyte with a composition of PO4 and 0.1 mol/jl of Na2B at a pulse voltage of 110 V at 0.2 A/cn2 Nohals electric fM, tmrl. A white matte porcelain-like layer with an ivory-like appearance was formed on top of this ornament. Surface roughness is 7.6μ
m, and the average layer thickness was 10.1 μm. Portlets were replicated to dimensional density.

Implementation fP13 An aluminum broach with a surface area of 1232 and initials C, D, was heated to a temperature of 338, 2% NaF, 7
% Na H2P O4,4% Na2B2O4,0
, 5% NH4F and 1% ammonia Co (OH
) connected as an anode in an aqueous electrolyte consisting of 500 V 1 [peak, 1 ms pulse time,
The coating was formed with a pulse frequency of 100 Hz and 100 Hz.

A maximum pulse current of 50A was measured. A matte blue, matt surface with high decorative value was obtained. After the coating process, the initials were reproduced with exact dimensions, with an error of only 8 μm.

Example 4 Surface area 400c made of 99.5% aluminum Al
The faceplate of the I12 electronic repeater was coated with 4% NaFs.
Anodization was performed with pulsed voltage in an aqueous electrolyte consisting of 6% Na COa and 4% Na2B4O7. In this case, the pulse time is 0.5 ms, the pulse current is 35 A, and the pulse frequency is 100 Hz.
The pulse voltage peak reached 410V. After a treatment time of 10 minutes, the face plate was uniformly coated all over with a 9 μm thick white, polished, porcelain-like decorative coating layer.

Example 5 After masking the back side of a picture frame with a surface area of 840 (to) 2 having a batten engraving, its front side was coated with 2% KMno.
A pulse voltage peak of 550 V, 58
The decorative coating was applied with a pulse current peak of A, a pulse time of 1.2 ms, and a pulse frequency of 100 Hz. 7
The light brown to rose-brown layer with a thickness of μm was matte and had a ceramic-like appearance and had a particularly decorative effect. The batan carving is only 12cm after the coating process.
Dimensional precision was reproduced with uniform thickness variation of μm. The average roughness was 8 μm.

Claims (1)

[Claims] 1. An electrochemical reaction determined by a pulsed voltage in a method for producing a decorative coating on a barrier layer-forming metal, aluminum, titanium, tantalum, zirconium, niobium or an alloy thereof in an aqueous electrolyte. and plasma chemical reaction, voltage peak of 250 V to 750 V, pulse time of 20 μs to 2 ms, pulse frequency of 35 Hz to 300 Hz, pulse current amount of 10 A to 120 A, electrolyte temperature of 318 K to 360 K, and 0.1 Ac.
A decorative coating on metal, characterized in that a matte decorative layer with a uniform thickness of 3 μm to 30 μm and a precise dimension is obtained under the condition of an average current density of m^-^2 to 1 Acm^-^2. How to make it. 2. Process according to claim 1, characterized in that the colored or black matte layer is coated with an additive containing transition metal ions in a concentration of 1% to 20% in an aqueous electrolyte. 3. Process according to claim 1 or 2, characterized in that homogeneous and heterogeneous color areas of different colors are produced by a multistep process using different electrolytes. 4. The method according to any one of claims 1 to 3, characterized in that an object having an ornament or a sculpture is used as a base. 5. A method according to any one of claims 1 to 3, characterized in that a flat large surface area object is used as the substrate.