Electrogalvanizing is a process in which a layer of zinc is bonded to steel in order to protect against corrosion. The process involves electroplating, running a current of electricity through a saline/zinc solution with a zinc anode and steel conductor. Zinc electroplating maintains a dominant position among other electroplating process options, based upon electroplated tonnage per annum. According to the International Zinc Association, more than 5 million tons are used yearly for both Hot Dip Galvanizing and Electroplating.The Plating of Zinc was developed at the beginning of the 20th century. At that time, the electrolyte was cyanide based. A significant innovation occurred in the 1960's with the introduction of the first acid chloride based electrolyte.The 1980's saw a return to alkaline electrolytes, only this time, without the use of cyanide. Compared to hot dip galvanizing, electroplated zinc offers these significant advantages:
Lower thickness deposits to achieve comparable performance Broader conversion coating availability for increased performance and color optionsBrighter, more aesthetically appealing, deposits
Step 1: Ways to Galvanize
The corrosion protection afforded by the electrodeposited zinc layer is primarily due to the anodic potential dissolution of zinc versus iron (the substrate in most cases). Zinc acts as a sacrificial anode for protecting the iron (steel). While steel is close to ESCE= -400 mV (the potential refers to the standard Saturated calomel electrode (SCE), depending on the alloy composition, electroplated zinc is much more anodic with ESCE= -980 mV. Steel is preserved from corrosion by cathodic protection. Conversion coatings (hexavalent chromium (CrVI) or trivalent chromium (CrIII) depending upon OEM requirements) are applied to drastically enhance the corrosion protection by building an additional inhibiting layer of Chromium and Zinc hydroxides. These oxide films range in thickness from 10 nm for the thinnest blue/clear passivates to 4 µm for the thickest black chromates.
Additionally, electroplated zinc articles may receive a topcoat to further enhance corrosion protection and friction performance.The modern electrolytes are both alkaline and acidic:
This is not harder than it looks.we are going to electroplate steel using zinc sulfate.But you can use zinc hydroxide or zinc chloride.
Step 2: Supplies for Galvanizing
1. Safety Wear
2. Metal Object To Be Plated (Must be Steel)
3. A Power Supply (3v-6v)
4. Zinc Sulfate/Zinc Hydroxide/Zinc Chloride
6. A Beaker (Glass Or Plastic Object Can Be Used Instead)
7. Zinc Metal (Can Be Found Inside Zn-C Batteries)
8. Sand Paper (120)
9. A Tissue Paper
11. Self Confidence and a Clean Workplace
Step 3: Making an Electrolyte
If you don't have zinc sulfate or zinc chloride.Here is a way to make it.
Zn+H2SO4=ZnSO4+H2 (It means that if you add zinc to sulfuric acid you will get zinc sulfate and hydrogen gas)
Zn+CuSO4(Aq)=ZnSO4+Cu (It means that if you add zinc to copper sulfate solution you will get copper and zinc sulfate)
Zn+NaOH=ZnOH+H2 (It means that if you add zinc metal into sodium hydroxide solution you will get zinc hydroxide and hydrogen gas)
Step 4: Prepare for the Plating
Dissolve a teaspoon of Zinc salt in about 100ml of water
Now place the metal to be plated and the zinc metal in the beaker.And don't let them touch each other.
Connect wires to the electrodes
now,connect the negative side of your power supply to the metal to be plated
Connect the positive side to the Zinc metal.Please make sure your metal and the zinc metal is clean and if not sand it with a sandpaper.Cleaning is highly recommend for a high quality plating.Also sand it after plating to.Do not use 120 for that!!! use a 360 it is good!
Step 5: Let It Go!
You can see some soapy form is forming,it's normal.Keep this for about 15 minutes and get it out.
And wipe the metal object with a tissue and again let it plate.
You have to do this for about 5 times for a perfect plating.
Step 6: Dry Your Object
When you finished plating,slowly wash it and let it dry for some hours.Your object will be ash color if you done it right.Please wash the beaker and dispose the chemicals properly.
Thanks for Reading
Comment and request for new science instructables! i will do them for you.