Question

6. To have a successful coating are: a) good choice for coating material. b) good coating technique. c) good surface preparation or good cleaning. d) all of the above 7. Coating layer must be a) Active or passive with environment. b) inert or non- passive with environment. c) inert or passive with environment. d) both a and b. 8. pH of normal sea water is a) 4.0. b) 7.0 c) less than 7.0. d) more than 7.0. 9. Good set-up for electroplating a) DC power supply and electrolyte solution. b) D.C. power supply, specific electrolyte solution and coated metal surface must be cathode. c) potential different between anode and cathode. d) none of the above. 10.Nickel metal (as barrier) is used to protect stainless steel alloy, its acts as: a) sacrificial barrier b) perfect barrier. c) inert barrier. d) passive barrier. 11. The Sacrificial anode of Cathodic protection technique must be a) more active metal. b) less active metal. c) the same metal. d) all of the above.

Answer 1

(6) To have a successful coating on a material, we should choose a good coating material. The type of coating materials used depends on the nature of metals. A good coating technique should be chosen, otherwise effective coating won't occur. Before coating, a good surface preparation and cleaning is important.

So all of the above measures are equally important. Hence option D is the right answer.

(7) For a higher durability, the coating material should not react with the surrounding environment. So the coating material should be passive and inert. Hence option C is the right answer.

(8) Sea water is slightly basic in nature, so the pH of normal sea water should be greater than 7.

So option D is the right answer.

(9) For a good electroplating set up, we should have a specific electrolyte, a DC power supply and the cathode should be the material on which coating has to be done and anode should be the coating material.

So option C is the right answer.

(10) Nickel is a non corrosive metal and it act as an inert barrier on metals. It is highly durable and act as a perfect barrier.

So option C is the right answer.

(11) Sacrificial protection involves protection using a more active metal. Metals like iron and steel are coated with more reactive material.

So option A is the right answer