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GATE MT 2022 Q26. Match the phenomena (Column I) with the descriptions (Column II)
(P)-(3) (Q)-(4) (R)-(1) (S)-(2)
(P)-(3)
See less(Q)-(4)
(R)-(1)
(S)-(2)
GATE MT 2022 Q29. A non-rotating smooth solid spherical object is fixed in the stream of an inviscid incompressible fluid of density 𝜌 (see figure). The flow is horizontal, slow, steady, and fully developed far from the object as shown by the streamline arrows near point O. Which of the following statement(s) is(are) TRUE?
Ans.- A
Ans.- A
See lessGATE MT 2022 Q43
Answer I2 = 220 A
Answer I2 = 220 A
See lesswhat happen when high hardness material is assembled into a job
It can wear the substrate material/base material where it has joined, this may be if the base material has lower hardness that top material and there rubbing action takes place.
It can wear the substrate material/base material where it has joined, this may be if the base material has lower hardness that top material and there rubbing action takes place.
See lessWhy peritectic reaction is called as an incomplete reaction?
L + alpha = beta (peritectic reaction) when beta phase will start forming because of reaction between alpha and the liquid. this beta which is formed on the alpha will immediately stop the reaction. because as soon as the thin layer of beta forms on the alpha, the contact between alpha and lRead more
L + alpha = beta (peritectic reaction)
when beta phase will start forming because of reaction between alpha and the liquid. this beta which is formed on the alpha will immediately stop the reaction. because as soon as the thin layer of beta forms on the alpha, the contact between alpha and liquid is gone. There is no contact, direct contact between alpha and liquid. So, any further increase of thickness of beta is not because of the peritectic reaction, but by peritectic transformation. So, any kind of contact, direct contact between alpha and liquid is not there. For a situation, for the reaction to proceed or reaction to go further, atoms in the alpha has to diffuse through this; has to diffuse through this layer of beta and come in contact with the liquid. The reaction is only possible, when there is a contact, otherwise reaction is not possible. So, as it forms another layer of beta, the thickness of the beta will increase. So, if any, for
any further reactions, atoms in the alpha again has to diffuse through this whole layer, come in contact with the liquid. And, the diffusion distance is time; is increasing. Therefore as the time increases, you need more time for the atoms to diffuse from alpha to come in contact with the liquid. And after sometime, this time will be very large. So, therefore no further diffusion is possible. And under such situations, you will always have some leftover alpha in the microstructure, which you cannot help. There will be always some leftover alpha present in the microstructure because incomplete reaction, this is the problem with all peritectic reaction.
reference : – http://www.nitttrc.edu.in/nptel/courses/video/113104068/lec15.pdf
See lessSketch the phase diagram of A and B, showing the phases present in each area of the diagram.
Picture shows the phase diagram. Its kind of peritectic phase diagram.
Picture shows the phase diagram. Its kind of peritectic phase diagram.
See lessWhat is corrosion and how can it be prevented?
Corrosion is the deterioration and loss of metal, or material by chemical, or electrochemical reactions with its environment. Example: rusting of iron and steel. Corrosion occurs when metals come in contact with corrosive atmosphere. Thus, corrosion can be prevented by: 1. Changing theRead more
Corrosion is the deterioration and loss of metal, or material by chemical, or electrochemical reactions with its environment.
Example: rusting of iron and steel.
Corrosion occurs when metals come in contact with corrosive atmosphere. Thus, corrosion can be prevented by:
1. Changing the metal, or/and design of parts
2. Modification of corrosive environment.
3. Separating the metal from the environment
4. Changing the electrode potential of the metal.
The most effective and economical method of preventing corrosion is to choose the most suitable geometrical design, most suitable material and then chose the most suitable protective method.
*Geometrical design*
Design should consider mechanical and strength requirements alongwith an allowance for corrosion. Slight change in design to prevent the corrosion mah prove highly economical in many cases.
Some simple rules should be kept in mind which designing a part:
1. Welded joints be preferred over riveted joints.
2. Avoid sharp bends in pipes when high velocities if fluids are involved.
3. Avoid contact with absorbent materials.
4. Avoid protruind parts.
5. Provide thicker section to take care of impingement attack.
*Proper selection of material*
Though mechanical strength, cost, fabricability, etc are the main factors in choosing a material, slight variations in compos or structure can help preventing corrosion. Use of purer metals (devoid of S, P in steel, Fe, Cu, Si in aluminium) improves the resistance but pure metals are expensive, soft and weak. Alloying elements are preferred as a choice to improve corrosion-resistance of metals.
Some factors to be considered before choosing a material for a particular service condition:
1. Metals on anodic end of galvanic series have less corrosion resistance than the metals on cathodic end ( more noble). Pure metals have more corrosion resistance than impure metals.
2. Coarse grained materials have higher corrosion resistance than fine grained materials.
3. Cold worked metal is anodic to annealed metal.
*Modification of environment*
1. Dehumidification of air: It is a process of reducing the moisture from air so that corrosion is almost prevented. Freeze drying
2. Removal of acid from water by neutralization such as by adding lime.
3. De-aeration and de-activation: Elimination of O2 is essential from the electrolyte to prevent the corrosion.
Inhibitors:
Inhibitor is a substance which when added in a small quantity to the corrosive environment decreases the rate of corrosion. Inhibitor either acts as a barrier by forming an adsorbed layer or retard the cathodic and/or anodic reactions.
Cathodic protection:
Sacrificial Anode method: In this method, another metal, which has more negative electrode potential than the structure to be protected is connected electrically to the structure, which now acts like a cathode.
Anodic protection:
If active -passive metals, particularly nickel, iron, chromium, titanium and their alloys (even alloys having these metals) are supplied a carefully controlled anodic current, they get passivated as protective film forms on anode material, the rate of corrosion decreases, or the corrosion is prevented.
Coatings:
Metallic coatings: Protecting the metals by metal coating is done as these are more durable, more decorative and provide better protection against corrosion.
Cathodic coating: The coating metal with respect to the bas metal. These coatings provide a physical barrier between the metal and the environment.
Anodic coatings: The coating metal is anodic to the underlying metal. The anodic coatings provide galvanic protection to the base metal, in addition to acting as a physical barrier between the base metal and the environment.
See lessGATE MT 2022 Q34.
I took the formula from the book by Reed-Hill (Pg. 159). They have given a simple relationship between the dislocation spacing, tilt angle and lattice parameter. sin (theta/2) = b/ 2d where theta is the misorientation angle, b is the burgers vector and d is dislocation spacing. b = lattice parameterRead more
I took the formula from the book by Reed-Hill (Pg. 159). They have given a simple relationship between the dislocation spacing, tilt angle and lattice parameter.
sin (theta/2) = b/ 2d
where theta is the misorientation angle, b is the burgers vector and d is dislocation spacing.
b = lattice parameter value.
So, sin (2 degree/2) = 0.143/2d
d = 4.097 nm = 4.10 nm
#I am not sure if this is the correct method. Let me know if there is another way to solve it.
See lesswhat about CSIR – NML apprentice ? will i get job after that ?
No, but you learn a lot who help you to crack the competition of any job
No, but you learn a lot who help you to crack the competition of any job
See lessWhat is metallurgy?
Metallurgy is the physical and chemical behavior between metallic elements, intermetallic compounds and mixture
Metallurgy is the physical and chemical behavior between metallic elements, intermetallic compounds and mixture
See lessGATE MT 2014 Q.16 Which one of the following minerals is a source of titanium?
Ilmenite
Ilmenite
See lessGATE MT 2022 Q7
Reynolds number
Reynolds number
See less