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Questions and Answers
What is the main purpose of reverse osmosis in water treatment?
Which condition must be met regarding water turbidity before treatment can be effective in high pressure boilers?
What phenomenon allows solvent to flow from lower concentration to higher concentration in reverse osmosis?
What is one of the disadvantages of using treatment equipment for high pressure boilers?
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What is the primary source of chemical fuels in nature?
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What is the gross calorific value (GCV) of the fuel in the given calculation?
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How does the presence of hydrogen in fuel affect its net calorific value (NCV)?
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What correction is made for heat liberated during sparking in the calorimeter experiment?
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What is the role of the acid correction in calorific value calculations?
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What factor is considered in calculating the cooling correction in a calorimeter experiment?
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What percentage of hydrogen is present in the fuel sample used in the first calculation?
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When calculating the calorific value, what must be adjusted for due to the weight of the calorimeter?
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What is the latent heat of steam used in the calculations?
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What is the main purpose of protective coatings on metals?
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Which of the following is an example of an anodic coating?
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Which method is NOT a technique for applying metallic coatings?
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What happens when an anodic coating breaks?
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What is the main characteristic of cathodic coatings?
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In the process of galvanization, which substance is iron dipped into?
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Which of the following statements is true about electroplating?
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What is a common practice to prevent corrosion in cathodic coatings?
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What type of functional groups do cation-exchange resins primarily contain for exchanging H+ ions?
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Which of the following statements best describes the regeneration of exhausted anion-exchange resins?
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What sequence is recommended for treating hard water to prevent precipitation of hydroxides?
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Which of the following is NOT a characteristic of cation-exchange resins?
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What is one significant advantage of the ion-exchange process for water treatment?
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During the anion-exchange process, what ion is typically replaced?
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What is the main structure of ion-exchange resins?
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What happens to H+ ions during the cation exchange process in water treatment?
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What is the primary role of the argon ions in the sputtering process?
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Which type of sputtering is used for non-conductive materials?
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What is a key advantage of using sputter deposition over thermal evaporation?
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What is formed when target atoms are knocked off during sputtering?
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What is the primary component of the gas used to create plasma in sputtering?
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In the sputtering process, what happens to the target atoms after being sputtered?
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Which application is NOT typically associated with the sputtering method?
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What characterizes the plasma state in which argon is used during sputtering?
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Study Notes
Protective Coatings
- Protective coatings act as a barrier between metal and the environment.
- They provide both corrosion protection and decorative value.
- Coatings are classified as inorganic or organic.
- Inorganic coatings: metallic and chemical conversion coatings
- Organic coatings: paints, varnishes, enamels, lacquers
Metallic Coatings
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Anodic coatings:
- Applied to cathodic metals using more anodic metals.
- Examples: Zinc, Aluminum, Cadmium coatings on iron.
- If the coating breaks, a galvanic couple forms and corrosion is enhanced.
- The anodic coating sacrifices itself to protect the base metal.
- The anodic coating is also called galvanization.
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Cathodic coatings:
- Applied to anodic metals using more cathodic metals.
- Examples: Tin, Chromium, Nickel coatings on iron.
- If a discontinuity forms, galvanic couple formation results in corrosion of the base metal.
- To prevent corrosion, frequent inspection and re-plating is required.
Methods of Metallic Coatings
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Hot dipping: Dipping the base metal in a molten metal
- Galvanizing: Dipping iron in molten zinc.
- Tinning: Dipping iron in molten tin.
- Metal cladding: Cladding the base metal with another metal.
- Electroplating: Coating the base metal by passing direct current through an electrolytic solution containing the coating metal's soluble salt.
- Electroless plating: Chemical plating, a coating process that uses a chemical reaction to deposit a coating without using an external electrical current.
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Physical Vapor Deposition (PVD): Thin film deposition of metals or compounds using a vacuum-based process.
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Sputtering: A PVD technique involving bombarding a target material with ions, leading to the ejection of atoms that deposit onto a substrate.
- Application of sputtering: VLSI fabrication, thin film coatings, and deposition of materials with high melting points.
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Sputtering: A PVD technique involving bombarding a target material with ions, leading to the ejection of atoms that deposit onto a substrate.
- Chemical Vapor Deposition (CVD): A thin film deposition technique using chemical reactions on a substrate.
PVD: Sputtering Method
- Plasma: A state of matter similar to gas with a portion of ionized particles.
- Process: A vacuum chamber is filled with argon gas, high voltage is applied causing ionization of argon to plasma, argon ions bombard the target material and the sputtered atoms are deposited onto the substrate.
- Advantages: Strong film adhesion, good film density and high deposition rates.
- Applications: VLSI fabrication, thin film coatings in diverse industries.
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Description
Explore the essential concepts of protective coatings in this quiz. Learn about the distinctions between inorganic and organic coatings, as well as the principles of anodic and cathodic coatings used for corrosion protection. Test your knowledge on how these coatings act as barriers and their decorative values in various applications.
