Monday, June 25, 2012

Chromium Plating

The functional advantages of trivalent chromium are higher cathode efficiency and better throwing power. The better throwing power means production rates are greater. Less energy is required because of the lower current densities required. The process is more robust than hexavalent chromium because it can withstand current interruptions.
From a health standpoint trivalent chromium is intrinsically less toxic than hexavalent chromium. Because of the lower toxicity it is not regulated as toughly, which reduces overhead costs. There are other secondary health advantages:
  • Higher cathode efficiencies lead to less chromium emitted into the air
  • Lower concentration levels result in less chromium waste
  • The anodes do not discompose
One of the disadvantages when the process was first introduced was that decorative customers disapproved of the color differences, however additives are now used to adjust the color. In hard coating applications, the corrosion resistance of thicker coatings is not quite as good as hexavalent chromium. The cost of the chemicals is greater, however this is usually offset by greater production rates and lower overhead costs. In general, the process must be controlled more closely than in hexavalent chromium plating, especially with respect to metallic impurities. This means processes that are hard to control, such as barrel plating, are much more difficult using a trivalent chromium bath.

Further to reviewing chromium plating processes , I was minded to take Mrs N to Rudesheim Magic Bike fest.
The tagging process is somewhat like entering a sterilisation clinic
A example of a fine minimalist backend
Amstrad* retro "hifi" unit, circa 1968.
Ladybird helmet captioned "eat more flies"
Single malt whisky container thoughtfully provided by Harley Davidson  - the idea of ownership is growing on  me.
Everyone except us was sporting some sort of uniform leder uniform
These over wide tyres suffer from tram lining - I thought that was well known?
Coming soon and in the next episode, Nikos World unearths the mystery of Tin Tin's space rocket at a secret location in North Germany (Peenemünde).

*Note to non-UK readers, in the 1960s Amstrad was a premier brand of astonishingly good audio equipment lovingly handbuilt in Cricklewood or Brentwood or some dump like that near London using at least one transistor and sold without warranty at Laskys in the Tottenham Court Road.  The owner of Amstrad went on to compere a situation comedy on BBC TV. 


  1. What a fascinating insight. As a welder, trivalent Cr3+ has always been of less concern to me than hexavalent Cr6+ - the fumes from the latter being more prevalent when using MMA techniques on various stainless, high nickel alloys, and even armour plate. So, MIG welding is preferable as this tends to emit Cr3+ which is less carcinogenic. (see Spini, Profumo et al, 1994, "Determination of hexavalent, trivalent and metallic chromium in welding fumes", Toxicological & Environmental Chemistry, Volume 41, Issue 3-4)

  2. Oh Alice

    The smell was virtually eliminated by introducing stabilised stainless steels 347 and 321 which contain Niobium or Titanium which sacrifices itself to save the Chromium, however, when lower carbon versions 304L and 316L were introduced the problem of weld decay was eliminated. These days the higher (in fact, normal) carbon versions are only used for applications where heat resistance is needed.

    As ever, thanks for taking the trouble to raed and comment on my humble attempt at "blagging".

    XS N

  3. I feel strangely confused after reading this post.

    But I love the bike pictures, does that count?

  4. I think you may need to do further research and chrome plate your GS. It'll make it easier to clean....

  5. Brandy

    So did I but thanks for looking

    Richard M

    What is this "clean" word?

  6. So, what you are saying is that you are a secret admirer of those chrome vehicles, and only ride a Beemer because of the colour scheme?

  7. Wonderful post Nikos. Of course, you could have shortened it by saying that chrome-loving motorcyclists have bugger-all taste anyway, so who gives a toss.

    Or as the Rusty Nuts long-distance club in NZ says, "Chrome don't get ya home" !

    I shall now leave...

  8. I love the hip flask - or, more accurately, fork flask. Personally, I would fill it with Springbank 1968 Scotch....and forget about the Harley.

  9. Dear Sir:

    Thank you for your concise explanation of a process that is the foundation of chrome polish sales in the United States. Also, are Harley events in Europe held in local police stations? There seems to be an absence of topless women wearing naught but beads and body paint.
    If you are going to import the motorcycle, you might as well go whole HOG, if you get my drift.

    Fondest regards,

  10. Geoff
    Wise torque from Rusty Nuts!

    Do the CoOp sell that beverage?

    The Polizei were strangely absent but I have difficulty in keeping my camera still these days


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