|
Which is better…plating with squares or with rounds?
Which is better…activated or non-activated nickel?
What do we mean by "activated nickel"?
What happens when activated nickel anode materials are used rather than non-activated product?
What are the advantages of using S®-Nickel Pellets?
Which is better…plating with squares or with rounds?
If you have been using 25 mm by 25 mm (1" x 1 ") electrolytic nickel squares as anode material, you may be asking if is there any advantage to switching to Vale R-ROUNDS®. Recently, Vale conducted research at its Plating Application Laboratory in Thompson, Manitoba to answer this question. The results were consistent with recorded observations made at six plating shops where different anode materials were compared under actual production conditions over a ten-month period. Here's what we learned:
- Electronickel squares and R-ROUNDS® are consumed at the rate of 1.1 grams per ampere-hour in bright nickel plating solutions containing chlorides. Switching from one-by-ones to R-ROUNDS® does not increase the consumption of nickel.
- Packing densities are approximately the same. The packing density of 25 mm by 25 mm squares is about 4.4 kg/dm3 that of R-ROUNDS® is 4.3 to 4.5 kg/dm3. Of course, packing density measurements are influenced by basket widths and by the stiffness of the titanium mesh, so some scatter in the data is always observed.
- Both products are made by electrowinning from the same electrolyte in Vale's Manitoba Division Refinery and have the same chemical compositions. Both contain a minimum of 99.99 per cent nickel plus cobalt and trace amounts of other elements. Both products exceed ISO Standard 6283, ASTM Standard B 39 and other national specifications for refined nickel.
- Anode residues formed by either product are about 0.05 per cent of the nickel dissolved...the lowest level of residue obtainable from any commercially available anode materials.
Back to Top
Which is better…activated or non-activated nickel?
If the two products have all the same attributes, why move to R-ROUNDS®? The key reason is that the button-like shape of R-ROUNDS® ensures better settling during plating and safer handling during basket loading. As well, R-ROUNDS® are adaptable to automated basket loading technology.
Squares tend to "hang-up" creating voids in the basket load. Voids can affect coating thickness uniformity, increase anode potentials to undesirable levels, and under extreme conditions, lead to the activation and corrosion of the titanium mesh. R-ROUNDS® electrolytic nickel has less tendency to bridge and thus the risk of running into these problems is reduced.
Because of this potential problem, some platers prefer to keep the nickel inventory in their baskets low; but there are major advantages to keeping them filled. Power costs are reduced because of lower resistance to current flow, baskets that are filled with nickel having low packing densities, such as 100 mm by 100 mm (4" x 4") squares, have to be filled more often and coating thickness uniformity is better controlled when baskets are kept filled, an easier job with R-ROUNDS®. If you are seeking the highest quality with minimum production hassles, R-ROUNDS® are clearly the preferred product.
Back to Top
What do we mean by "activated nickel"?
The answer lies in a minute amount of sulfur added to high purity nickel products that can make all the difference in your plating operation.
Vale makes two activated products - S-ROUNDS® Electrolytic Nickel and S®-Nickel Pellets. With the exception of the addition of the 0.025 per cent sulfur, their nickel content and purity is very similar to Vale's non-activated products - both exceed the requirements of ASTM Standard B39 and other international specifications.
Back to Top
What happens when activated nickel anode materials are used rather than non-activated product?
If the plating solution does not contain chloride ions, non-activated anode materials passivate and cease to function, while S-ROUNDS® and S® -Nickel Pellets will dissolve at 100 per cent efficiency even if there are no chlorides in solution. Most decorative nickel plating solutions contain chlorides, but solutions used for electroforming and engineering applications may contain little if any. For these applications, Vale's activated products are essential.
One misconception is that activated products are consumed at faster rates than non-activated products. This is incorrect. In fact, both are consumed at the same rate during plating.
Another advantage of activated products is that they offer less resistance to current flow and dissolve at significantly lower anode voltages. thereby conserving energy and reducing power costs in the plating shop.
While all plating materials form residues, activated materials form black nickel sulfide residues, which must be retained in anode bags to prevent roughness in the nickel deposit. Actually, this residue has a useful function, acting as a scavenger for copper ions and removing unwanted copper impurities from the plating solution.
It is recommended that anode bags should be used with non-activated products as well, as they dissolve with less uniformity and form small amounts of metallic residue which can cause roughness at the cathode.
R-ROUNDS®, S-ROUNDS® Electrolytic Nickel and S®-Nickel Pellets form the least amount of residue, Nickel Flats form intermediate amounts of residue and Nickel Pellets for Plating the most.
Adding it all up, the score card shows S-ROUNDS® and S®-Nickel Pellets on top. They dissolve in all plating solutions, lower power costs and the non-metallic residue gets rid of copper impurities. They are the versatile and cost-effective answer to your nickel plating needs.
Back to Top
What are the advantages of using S®-Nickel Pellets?
In the fast-growing electroforming business, the fastest-growing product is Vale S-Nickel Pellets, made using the carbonyl process at Vale’s Refinery in Clydach, Wales.
Major users of S®-Nickel Pellets include compact disc stampers, producers of optical recording discs, textile printing screens, holograms and thin nickel foil. It's also popular for continuous plating of steel strip and for making electroforming foam used in nickel battery electrodes.
One of the purest anode materials available, the manner in which S-Nickel pellet is produced results in the repeated deposition of nickel, giving the product an onion skin structure when examined in cross-section. Aside from the sulfur, which is closely controlled at 0.025 per cent, S®-Nickel Pellets contains only minute amounts of impurities, ideal for demanding applications. As well, its spherical shape provides a degree of flowability unmatched by other forms of plating nickel. This means that anode baskets can easily be filled directly or with the aid of loading devices. In fact, fully automatic loading devices are often used with S®-Nickel pellets in today's large state-of-the art operations.
There are other advantages to S®-Nickel Pellets. The incorporated sulfur results in a significant reduction in power cost, varying from two to twenty per cent, depending on current density. Because it is an activated product, S®-Nickel Pellets don't form a passive oxide surface film and dissolves uniformly, settling well in baskets without bridging.
As well, the efficiency of dissolution doesn't depend on the presence of chlorides in the plating bath, so they can be eliminated or held at low levels. And, as chlorides increase the internal stress of nickel deposits, S®-Nickel Pellets allow you to reduce the level of chlorides in solution.
S®-Nickel Pellets can be conveniently handled by both large production shops and smaller manual operations. They come in packages from as small as a 10kg plastic bag to a 250kg drum.
Back to Top
© Vale 2010
Last Updated: Friday, March 30, 2012
|