Preventing Carburizing By Copper-plating

: The Working Of Steel

Copper-plating has been found effective and must have a thickness

of 0.0005 in. Less than this does not give a continuous coating.

The plating bath used has a temperature of 170 deg.F. A voltage of

4.1 is to be maintained across the terminals. Regions which are

to be hardened can be kept free from copper by coating them with

paraffin before they enter the plating tank. The operation is as


r /> Operation

No. Contents of bath Purpose

1 Gasoline To remove grease

2 Sawdust To dry

3 Warm potassium hydroxide solution To remove grease and dirt

4 Warm water To wash

5 Warm sulphuric acid solution To acid clean

6 Warm water To wash

7 Cold water Additional wash

8 Cold potassium cyanide solution Cleanser

9 Cold water To wash

10 Electric cleaner, warm sodium Cleanser to give good

hydroxide case-iron anode plating surface

11 Copper plating bath of copper Plating bath

sulphate and potassium cyanide

solution warm

There are also other methods of preventing case-hardening, one

being to paint the surface with a special compound prepared for

this purpose. In some cases a coating of plastic asbestos is used

while in others thin sheet asbestos is wired around the part to

be kept soft.