Did you ever want to know what hard chrome plating was?
Hard chrome plating is an electroplating process in which chromium is deposited from a chromic acid solution.
The thickness of hard chrome plating ranges from 2 – 250 micrometers.
A variety of hard chrome include micro-cracked chromium, micro-porous chromium, porous chromium and crack free chromium.
It is vital that the micro-cracked coatings and porous coatings have a minimum thickness between 80 – 120 micrometers in order confer adequate corrosion resistance.
The formation of micro-porous chromium is achieved by a specialised plating method involving the use of inactive suspended particles.
Porous chrome plating is manufactured by etching electro deposited chromium – these are designed to retain lubricant, for sliding type applications.
Chrome plating is used mostly for resistance against wear and corrosion as opposed to its low friction characteristics.
However, there are environmental concerns associated with disposing the plating solution, which has lead to many users of chrome plating to seek out alternative coating methods.
Though we all see chrome in our day to day lives, not many people know about it. So, just what exactly is Chrome and how do you make it? Find out in our latest blog right here! What exactly is chrome?
Chrome (short for chromium), is a metal that is applied to the surface of an object. A product cannot be made of solid chrome, instead a thin layer is applied in a manner that’s either chrome plating, chrome dipping or chroming. The objects in which chrome can be applied to are endless, yet they’re mostly made up of steel. Other elements that can be used are copper, brass and aluminium.
What’s good to remember is that, just because something holds a shiny finish doesn’t mean it has a chrome finish. Many people would say that aluminium motorbike parts that have been polished to a high level of brightness are “chrome”, yet they’re actually not.
So, how exactly can you tell the two apart? It can be difficult at times to see differences, but when they’re compared up close, chrome has itself a massive advantage over a simple polished metal. Chrome plating is a highly reflective method, holding a bluer and more specular finish than others.
Chrome plating will reflect everything, holding a fantastic finish that cannot be put into words.
What’s the difference between the chrome processes?
Chrome is applied to surfaces through a process called ‘electroplating’, which gives an even level of application on all areas of the surface. It isn’t just dripped on either, so electroplating is the only process used in this manner.
It’s also good to know that even though they’re all applied in the same manner, not all chrome processes will offer the same outcome. There are two separate applications of chrome plating: “hard chrome plating” and “decorative chrome plating”.
So, what are hard and decorative chrome plating?
Hard Chrome Plating
Not many people would have an experience with hard chrome plating, as it’s a process of chrome plating where the application of the coat is fairly heavy. The coat is applied in this manner for wear resistance, oil retention and various ‘wear’ purposes that may have an effect on the surface. Some examples would be piston rings.
Decorative Chrome Plating
Decorative chrome plating is regularly called nickel-chrome plating, simply because it involves electroplating nickel onto the object prior to plating it with chrome. The nickel plating process provides a layer of nickel which gives the surface smoothness, corrosion resistance, and even reflectivity. The chrome plating applied is exceptionally thin.
What other questions do you have on chrome plating?
There are a number of corrosion protection methods, but what exactly are they?
Active corrosion protection
The end goal of active corrosion protection is mostly to influence the reactions which often happens during corrosion, with the result being able to control not only the package contents, but also the reaction itself. This is done in such a manner that corrosion is avoided. Examples of this can be found in the development of corrosion-resistant alloys, along with inhibitors.
Passive corrosion protection
In passive corrosion protection, damage is ultimately prevented by isolating the contents from the aggressive corrosive agents by using various protective layers or films. However, though this is a form of protection, using this type of corrosion protection will not change the ability of the packaging contents corrosion chances, nor will it change the aggressive levels of the corrosive agent. This approach is known as ‘passive corrosion’ protection.
Permanent corrosion protection
The purpose of permanent corrosion protection is to provide any protection at the place of use. The stresses presented by biotic, climatic and chemical factors are often slight in this situation. Machines are located in factory sheds and are therefore protected from the extreme variations in temperature that can happen, which is the common cause of condensation.
Temporary corrosion protection
The stresses that can occur during transport and storage are often greater than those that occur at the place of use. Stresses can be manifested, for example, from extreme variations in temperature, which often result in a risk of condensation.
Have you ever wondered what’s the difference between decorative chrome or hard chrome plating?
Chromium is about the same hardness in both decorative chrome and hard chrome plating, about 800 to 1000 VHN (which is incredibly heavy). The main difference is found in the thickness of the deposit.
For the decorative purpose of chrome, it is seated best on nickel, which adheres incredibly well to copper – the combination of all three offers possibly the best corrosion protection resistance available. Decorative chrome thickness can vary from anywhere between a few hundredths of a mil to one mil. The mirror finish will effectively only be as good as the finish that is on the surface before the chrome, so it’s all a very difficult process at times.
For the purpose of being functional, or take either take advantage of the extremely low friction that chrome holds or for building surfaces and pistons, hard chrome will be plated with a thickness anywhere between 1 to 50 mills.
When used as a bearing surface, chrome simply must be micro-finished, something which will then provide a level of friction much lower than any other metal when used against the likes of steel, iron, brass, bronze or aluminium alloys. There’s something that you mustn’t do; Do not use chrome against chrome. Chrome is much harder than casehardened steel, so we are then left with a perfect set-up for longwearing working surfaces. Chrome will resist pretty much all organic and inorganic compounds and acids, except hydrochloric acid.