1. Which of the following metals has the highest thermal conductivity? C
(a) carbon steel
(b) stainless steel (
(c) aluminum ANS >>> (c) aluminum
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, 2. The Ellingham diagram C
(a) is a plot of thermal conductivity against temperature.
(b) shows the free energy of oxide formation against temperature.
(c) shows the rate of oxidation of metals against temperature. ANS >>> (b)
shows the free energy of oxide formation against temperature.
3. True or False?
A metal with a high negative free energy of oxide formation will generally
require
greater shielding from the atmosphere during welding. ANS >>> True
4. Electricity can be conducted by ANS >>>
(a) atoms and electrons.
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, (b) electrons and ions. C
(c) only ions. ANS >>> (b) electrons and ions. C
5. Which of the following elements is often present in submerged arc fluxes
to improve arc
stability?
(a) copper (
(b) potassium (
(c) nickel C
(d) tungsten ANS >>> (b) potassium (
6. Thoria is added to tungsten electrodes for what purpose? ANS >>> To
increase thermionic emission by lowering the work function.
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(a) carbon steel
(b) stainless steel (
(c) aluminum ANS >>> (c) aluminum
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, 2. The Ellingham diagram C
(a) is a plot of thermal conductivity against temperature.
(b) shows the free energy of oxide formation against temperature.
(c) shows the rate of oxidation of metals against temperature. ANS >>> (b)
shows the free energy of oxide formation against temperature.
3. True or False?
A metal with a high negative free energy of oxide formation will generally
require
greater shielding from the atmosphere during welding. ANS >>> True
4. Electricity can be conducted by ANS >>>
(a) atoms and electrons.
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, (b) electrons and ions. C
(c) only ions. ANS >>> (b) electrons and ions. C
5. Which of the following elements is often present in submerged arc fluxes
to improve arc
stability?
(a) copper (
(b) potassium (
(c) nickel C
(d) tungsten ANS >>> (b) potassium (
6. Thoria is added to tungsten electrodes for what purpose? ANS >>> To
increase thermionic emission by lowering the work function.
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