(1) Chemical conversion coating for metals:
METHOD OF ADHERING A COLORED This method includes phosphates treatment method,
ELECTROPLATING LAYER ON A chromates treatment method, and sulphurizing etc. Al
ZINC-ELECTROPLATED STEEL ARTICLE though the chemical conversion coating can be used for
«. „x^~~T„.,~ 5 the corrosion resistant treatment for the zinc-plated
BACKGROUNDED SUMMARY OF THE stee] has ... ^ ^ ... and
the sulphites are highly toxic and the phosphate is diffiThe present invention relates to a method of adhering cult to dissolve. This causes environmental pollution, a colored electroplating layer on zinc-electroplated Furthermore, the corrosion resistant effect of this steel articles. The method utilizes an alternating current method is not ideal for high corrosion areas such as power supply which supplies electricity having a fre- areas cjose t0 tjje sea quency of 10-20 Hz, voltage of 60-120 V, and current (2) Coati treatmentdensity of 20-80 Amp/dM*; and an aqueous electroplat- Ther£ ^ ^ of ^ whjch are feem used
ing solution which contains 150-200 g/1 of silicate, t. . ,.
,.r-n „ c .. , , ., , , ,„ „ r , .' 15 in this method, e.g. PVC resin, acrylic resm, epoxy
15-20 g/1 of sodium hydroxide and 5-50 g/1 of cobalt , ... „ , . I ■
salt. The electroplating solution is kept at a constant rfln'or *e 1,kf Ho^e/' thf COatmg °n *f ZTM'
temperature of 20° C.-30" C. In this method, two stages PIated steel art,cles which have been coated WIth these
are utilized to perform the electroplating and adhere a resins have the tendency to peel off after being exposed.
colored electroplating layer so that the surface of the , In particular the adherence between a paint and the
zinc-electroplated layer can adhere a blue electroplated surface of a zinc-plated layer is not good if the paint is
layer. Thus the aesthetics and the corrosion-resistant applied on a steel article which has just been zinc-elec
capability of the zinc-electroplated layer can be en- troplated.
hanced because of the colored electroplated layer ad- (3) To produce an interference coloring alloy by adding
hered to the surface of the zinc-electroplated layer. In 25 elements such as titanium, magnesium, or manganese
the method mentioned hereinabove, the cobalt salts during the process of hot-dip galvanizing:
may be replaced by metal salts such as manganese salts This method produces alloy products in which the
of 5-20 g/1, chromium salts of 5-15 g/1, iron salts of uniformity and the recurrence has to be overcome.
2-15 g/1, and tin salts of 20-40 g/1 so that the adhered Furthermore, the interference coloring alloy produced
color of the surface of the zinc-electroplated layer 30 with this method is relatively thin and does not have a
would be brown, green, white, or grey, respectively. good anti-wearing property.
The main object of the present invention is to apply a (4) Electrochemical coloring treatment:
colored electroplated layer on the surface of a zinc-elec- In ^ a Canadian company named Comince devel
troplated article so as to enhance corrosion-resistance. „ „. ... • ~j- J. . J \ u- u
, , , . oped APCF (zinc anodized treatment procedure) which
This is achieved by an alternating current electroplating it . ,. , , , . , ... . ,
, .... . ' , ° , , v ~ is an anodized treatment which utilizes zinc chromate
method utilizing a voltage, a current, and a constant , . , , . , . , ,
r ,■ •. j T ■ „, , and zinc ammonium phosphate electrolyte, with the
temperature of a limited range. In this method, salts . . , f . •
contained in the solution and used in the electroplating voltaSe raised t0 200V' t0 Produce a Sreen coatmS- In process result in a colored electroplating layer being 1971> the U'S- Navv set UP standards for zinc and zinc adhered to the surface of the zinc-electroplated layer of 40 aIlo>' anodized treatment coating, m which there are the zinc-electroplated steel article and the aesthetics four kinds of colored coating treatment procedures, i.e., and the corrosion resistance of the zinc-electroplated APCF (green coating), SSC (light grey coating), SSCV steel article are thereby enhanced by the colored elec- (dark grey coating), and SSMN (brown coating). These troplated layer. manufacturing procedures use solutions such as chroZinc is an amphoteric metal which is very active and 45 mates, hydrofluoric acid, and permanganates, which are which has the corrosion resistance capability. For this highly toxic and highly corrosive. Thus there is a tenreason many commercially available products, which dency for causing environmental pollution, are made of iron or the like, such as home appliances, The inventor of the present invention mitigates the automobile body, bridge structure, electric power trans- problems such as coloring the zinc-plated layer and the mission equipment utilize zinc as corrosion resistant 50 thinness of the layer. The inventor conducted research layer. Since the surface coating of the zing layer is soft in the technique relating to the zinc-plating of steel and susceptible to wearing and corrosion, and the zinc articles and the different clay coatings, layer becomes zinc oxide after being oxidized, the ad- The present invention provides mainly a method for herence between the zinc oxide and the iron maternal is providing a colored layer adhered to zinc-plated layers deteriorated. This causes the zinc oxide to peel off the 55 which are zinc j of zinc> hot.di alvanized
iron material. Furthermore, the surface of conventional , . , . , ,. . , .
, , , ..... ,. , . , . , zinc, electroplated zinc, die casting zinc, and thermal
zinc-plated steel articles is silver white which lacks , . , , ^, . , . , , .
.... , ,■ • c ,, c 0 .. „ sprayed zinc. In this method, the zmc-plated layer has
aesthetics and limits the field of usage. Conventionally, , . ,, . ,' \ , .
1 „a,u„j„ = =„ i„,,=^ ,a t\,o „<• enhanced adherence, microhardness, and erosion-resist
several methods are employed to improve the color 01 .
the surface of the zinc-plated layer and to inhibit the 60 anI ProPerties
consumption of the zinc layer on the surface; e.g. (1) BRIEF DESCRIPTION OF THE DRAWINGS chemical conversion coating for metals: (2) coating
treatment; (3) to produce an interference coloring alloy FIG- 1 shows the voltage and the current density in
by adding the elements such as titanium, magnesium or each stage of the two-stage electroplating processing of
manganese during the process of hot-dip galvanizing; 65 the present invention; and
and (4) electrochemical coloring treatment. However, FIG. 2 shows a picture, which has been enlarged
each of the above-mentioned methods has the following with an electron microscope, of a sample obtained by
drawbacks: the method of the present invention.