Syllabus

Plating Practice

1. INTRODUCTION TO PLATING
1.1 Explain why plating is such a popular way of putting metal coating onto substrates.
1.2 Deduce what properties of a plated coating should be specified so that the plated part would be suitable for a certain use.
1.3 List the main processes in a typical plating sequence.
1.4 State why it so important to rinse the parts in water after different processes.

2. SURFACE PREPARATION AND PRETREATMENT
2.1 Classify, according to the properties and likely contaminants on their surfaces, the metal and non-metal substrates that are commonly plated.
2.2 Describe the construction and operation of three types of degreasing units.
2.3 Know how to clean common metals using alkaline solutions.
2.4 Know how to remove oxides from the surface of common metals, using acid solutions.
2.5 Discuss the causes of hydrogen embrittlement of steel and know how to prevent and alleviate it.
2.6 Know how to plate onto the following substrates:
   2.6.1 Zinc alloy diecastings.
   2.6.2 Aluminium and its alloys.
   2.6.3 Stainless steel and iron.
2.7 Prepare plastics to receive adherent metallic coatings.

3. ELECTROPLATING OF METAL COATINGS AND APPLICATION OF CONVERSION COATINGS
3.1 List the main metals that are electrodeposited and describe plating processes in a clear manner.
3.2 State the main reasons for using these popular electrodeposited coatings and relate these to the most common substrates.
3.3 Describe and compare the three most important plating baths that are used for electrodeposition of copper.
3.4 Be able to make up these plating baths from chemicals.
3.5 Be able to electrodeposit copper from these plating baths.
3.6 Describe and compare the most important platings baths that are used for the electrodeposition of nickel.
3.7 Be able to make up these nickel plating baths and electrodeposit nickel from them.
3.8 State how improved electrodeposited nickel coatings can be obtained.
3.9 Describe the common types of plating baths used for electrodeposition of chromium and explain the importance of their operating conditions.
3.10 Be able to make up typical chromium plating baths and electrodeposit chromium from them.
3.11 Be aware of the corrosion behaviour zinc and cadmium coatings in different environments.
3.12 List and describe the types of plating solutions used for the electrodeposition of zinc.
3.13 Be able to make up and operate these plating solutions.
3.14 Be able to make up and operate a cadmium cyanide plating solution.
3.15 Describe and compare the most important types of plating solutions used for the electrodeposition of tin.
3.16 Be able to make up and operate acid sulphate and alkaline stannate tin plating solutions.
3.17 List and know the uses of the various types of silver cyanide plating solutions.
3.18 Be able to make up and operate these silver plating solutions.
3.19 List and describe the different types of plating solutions used for the electrodeposition of gold and gold alloys.
3.20 Describe the main uses of coatings deposited from these different gold plating solutions.
3.21 Explain what is meant by conversion coatings and list their different types.
3.22 List and compare the different types of chromate coatings used on zinc and cadmium.
3.23 Be able to make up and use a simple chromating solution for zinc coatings.
3.24 Know how to test chromated and unchromated zinc coatings for their corrosion resistance.
3.25 Describe methods of using chromates to apply anti-tarnish films on copper and silver.
3.26 Explain how some organic chemicals can delay copper and solver tarnishing.

4. THE PLATING OF METAL COATINGS WITHOUT ELECTRICITY
4.1 Discuss the meaning of the terms ‘Immersion Coating’, ‘Displacement Reaction’, and ‘Exchange reaction’.
4.2 Explain the significance of the Galvanic Series.
4.3 Discuss how the behaviour of dissimilar metals in contact with one another is governed by the Galvanic Series.
4.4 State the basic chemistry underlying electroless deposition processes.
4.5 List the main types of electroless deposition and immersion coatings in commercial use.
4.6 State the effects on the rate of electroless deposition of change of pH, temperature and reactant concentration.
4.7 Discuss the underlying causes of ‘runway’ conditions in electroless deposition systems.
4.8 Describe the recommended procedures for day-to-day operation of electroless baths.

5. PLANT AND EQUIPMENT USED FOR PLATING
5.1 Be aware of the laws governing siting of industrial premises.
5.2 State the laws affecting the operation of a Metal Finishing plant.
5.3 Explain the concept of work flow through a Metal Finishing plant.
5.4 Describe how plating tanks are constructed, heated and agitated.
5.5 Explain how a pump should be connected to a plating tank.
5.6 State the function of a jig (rack).
5.7 Describe and compare the different types of anodes and their correct installation.

6. THE TREATMENT AND DISPOSAL OF METAL FINISHING WASTES.
6.1 Discuss how the discharge of toxic effluent can cause danger, damage or loss.
6.2 List the main toxic wastes from Metal Finishing,
6.3 Explain how heavy metal ions can be removed by alkaline precipitation and flocculation.
6.4 List the main methods for disposal of cyanides.
6.5 Know which cyanide disposal methods are most appropriate for concentrated and dilute solutions in large and small volumes.
6.6 Explain the principles of ion-exchange and its application to effluent treatment.
6.7 Discuss the concept that valuable materials can be recovered from effluent streams.
6.8 List alternatives to precipitation for recovery or removal of metal ions from effluent streams.

7. MAINTAINING HEALTH AND SAFETY IN THE PLATING SHOP
7.1 State what is required of an employer under the Health & Safety at Work Act (1974).
7.2 State what is required of an employee under Health & Safety at Work Act (1974).
7.3 List some of the major safety hazards in a Metal Finishing shop.
7.4 List some of the major health hazards in a Metal Finishing shop.
7.5 List the most important items of safety equipment in a Metal Finishing shop.
7.6 Discuss the importance and role of training in the prevention of accidents.