Instruction
- Total number of questions : 20
- Time allotted : 30:00 Minutes:Seconds.
- Each question carry 1 mark, no negative marks.
- DO NOT refresh the page.
- All the best
Ceramic Raw Materials [ Question No: 1 To 20 ] :
Consider the following statements about bulk bag handling.
1. Bags should be lifted by all four loops together.
2. Stacked bags can lean and topple if the fill is uneven.
3. An emptied bag may be reused for a different material without cleaning.
All of the following control dust at a transfer point EXCEPT
State whether the following is true or false.
Segregation on filling can be reduced by using several fill points instead of one.
Assertion (A): Reactive alumina is calcined and then milled rather than simply calcined to a fine size.
Reason (R): The calcination that converts the hydroxide to alpha alumina inevitably produces sintered aggregates.
All of the following raise the cost of a synthetic powder EXCEPT
Assertion (A): Specific surface area is often quoted instead of a particle size for synthetic powders.
Reason (R): The nitrogen adsorption measurement is quick and does not require the particles to be dispersed.
All of the following change the mass actually weighed out EXCEPT
Assertion (A): A firing trial is still run on a clay whose full chemical and mineralogical analysis is already known.
Reason (R): Fired colour and shrinkage depend on interactions that an analysis does not predict reliably.
Assertion (A): The glassy phase in a fired ceramic can be estimated from a diffraction pattern.
Reason (R): An amorphous phase contributes a broad hump whose area is proportional to its quantity.
Consider the roles of flotation reagents.
1. A collector makes a chosen mineral hydrophobic.
2. A depressant prevents an unwanted mineral from floating.
3. A frother makes the mineral surface water-repellent.
State whether the following is true or false.
A single material can act as a flux in one body and a filler in another.
Assertion (A): Aluminium nitride has displaced beryllia in many electronic substrate applications.
Reason (R): Beryllia powder is highly toxic and demands stringent handling precautions.
Consider the following statements about refractory classification.
1. Silica brick is an acid refractory.
2. Magnesia brick is a basic refractory.
3. The terms refer to the pH of the material in water.
State whether the following is true or false.
Silicon nitride sinters readily without any additives.
Alumina is the most widely used engineering ceramic chiefly because it combines
State whether the following is true or false.
Clay particles are plate-like because they have been ground very finely.
A clay loses 13 per cent of its mass on ignition. How much fired material results from 200 kg of dry clay?
Bentonite is added to a ceramic body in small quantity in order to
Illite differs from montmorillonite in that illite
Assertion (A): A clay slip can flocculate into an open structure even though all the particles carry a net negative charge.
Reason (R): The edges of the particles can be positively charged and attract the negative faces.
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20
Ceramic Raw Materials [ Question No: 1 To 20 ] :
Consider the following statements about bulk bag handling.
1. Bags should be lifted by all four loops together.
2. Stacked bags can lean and topple if the fill is uneven.
3. An emptied bag may be reused for a different material without cleaning.
Your Answer : (Not Answered)
Correct Answer : B
The first two are correct. The third invites cross-contamination, which in a ceramic body can mean an iron speck or an unexpected flux appearing in a fired ware with no traceable cause. A bag once used should be marked for that material only.
All of the following control dust at a transfer point EXCEPT
Your Answer : (Not Answered)
Correct Answer : D
Dry sweeping puts settled dust back into the air, which is why vacuum or wet methods are required instead. The other three all stop the dust being generated or capture it at source. Housekeeping method is as much a control as the plant design.
State whether the following is true or false.
Segregation on filling can be reduced by using several fill points instead of one.
Your Answer : (Not Answered)
Correct Answer : D
Multiple points build several smaller heaps with shorter slopes, so less rolling occurs and the radial sorting is much weaker. A rotating distributor achieves the same end in a single vessel. Chute design at the fill point matters as much as the count.
Assertion (A): Reactive alumina is calcined and then milled rather than simply calcined to a fine size.
Reason (R): The calcination that converts the hydroxide to alpha alumina inevitably produces sintered aggregates.
Your Answer : (Not Answered)
Correct Answer : D
Both are true and the reason gives the necessity: the temperature needed for the phase change is high enough to bond the crystals together, so milling is the only way back to a submicron powder. The milling media then become a source of contamination.
All of the following raise the cost of a synthetic powder EXCEPT
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: using a continuous rather than a batch reactor
A continuous reactor generally lowers cost: it needs no filling and emptying cycle, gives more uniform product and uses the equipment fully. The other three all raise it - alkoxides are far dearer than salts, extensive washing and controlled drying add steps and time, and a batch autoclave adds a pressure vessel with its own cycle in the middle of the route.
Assertion (A): Specific surface area is often quoted instead of a particle size for synthetic powders.
Reason (R): The nitrogen adsorption measurement is quick and does not require the particles to be dispersed.
Your Answer : (Not Answered)
Correct Answer : D
Correct answer: Both A and R are true, and R is the correct explanation of A
Both are true and the reason gives the practical advantage. Nitrogen adsorption measures the whole accessible surface of a dry powder in a routine analysis, with no dispersion, no dispersant and no assumption about shape. An equivalent particle diameter can be calculated from it if the density is known, and for a fine powder the surface area is in any case the more directly relevant quantity.
All of the following change the mass actually weighed out EXCEPT
Your Answer : (Not Answered)
Correct Answer : B
Loss on ignition affects the fired mass but not what goes on the scale, since the material is weighed before it is fired. The other three all alter the quantity that has to be weighed out on the day. Only the kiln loss is invisible at the scale.
Assertion (A): A firing trial is still run on a clay whose full chemical and mineralogical analysis is already known.
Reason (R): Fired colour and shrinkage depend on interactions that an analysis does not predict reliably.
Your Answer : (Not Answered)
Correct Answer : D
Both are true and the reason gives the necessity: trace iron and titania, particle size and the mineral assemblage all interact during firing, so the only dependable prediction is a small-scale repetition of the process itself.
Assertion (A): The glassy phase in a fired ceramic can be estimated from a diffraction pattern.
Reason (R): An amorphous phase contributes a broad hump whose area is proportional to its quantity.
Your Answer : (Not Answered)
Correct Answer : C
Both are true and the reason gives the method: the hump is measured against the crystalline peaks, usually with an added internal standard, which turns what looks like background into a measurement. The method needs care but is well established.
Consider the roles of flotation reagents.
1. A collector makes a chosen mineral hydrophobic.
2. A depressant prevents an unwanted mineral from floating.
3. A frother makes the mineral surface water-repellent.
Your Answer : (Not Answered)
Correct Answer : B
The first two are correct. The third confuses the frother with the collector, since the frother's job is to stabilise the bubbles rather than to alter any mineral surface. Without a frother the bubbles would burst before reaching the surface.
State whether the following is true or false.
A single material can act as a flux in one body and a filler in another.
Your Answer : (Not Answered)
Correct Answer : B
Correct answer: True
The role depends on the temperature reached and on what surrounds it, not on the material itself. Quartz is a filler in an earthenware body and takes part in the melt in a porcelain fired higher. Alumina fluxes nothing in a refractory and stiffens the melt in a glaze. The classification describes what a material does in a particular body at a particular temperature.
Assertion (A): Aluminium nitride has displaced beryllia in many electronic substrate applications.
Reason (R): Beryllia powder is highly toxic and demands stringent handling precautions.
Your Answer : (Not Answered)
Correct Answer : C
Both are true and the reason gives the driver: the thermal performance of beryllia is better, so the substitution is made on grounds of safety rather than of technical merit. Toxicity has settled a question that performance alone would not.
Consider the following statements about refractory classification.
1. Silica brick is an acid refractory.
2. Magnesia brick is a basic refractory.
3. The terms refer to the pH of the material in water.
Your Answer : (Not Answered)
Correct Answer : D
The first two are correct. The third misreads the terminology, which describes compatibility with furnace slags rather than any behaviour in aqueous solution. The two classes must also be kept apart within a single lining.
State whether the following is true or false.
Silicon nitride sinters readily without any additives.
Your Answer : (Not Answered)
Correct Answer : C
Covalent bonding makes diffusion very slow, so sintering aids that form a liquid phase are normally required. Those additives leave a boundary phase that limits high-temperature performance, which is the standing compromise for the material.
Alumina is the most widely used engineering ceramic chiefly because it combines
Your Answer : (Not Answered)
Correct Answer : A
It is hard, chemically resistant, a good electrical insulator and available in quantity at a price that many applications will bear. Nothing else matches that particular combination across so wide a range of uses. It accounts for the great majority of technical ceramic tonnage.
State whether the following is true or false.
Clay particles are plate-like because they have been ground very finely.
Your Answer : (Not Answered)
Correct Answer : D
The shape follows from the layered crystal structure and is present in the natural mineral before any grinding. Milling reduces the size but does not create the habit. Even a coarsely crushed clay shows the same plate-like particles.
A clay loses 13 per cent of its mass on ignition. How much fired material results from 200 kg of dry clay?
Your Answer : (Not Answered)
Correct Answer : C
Thirteen per cent of 200 kilograms is 26 kilograms lost, leaving 174. Loss on ignition must be allowed for whenever a fired yield or a batch cost is being calculated. The figure is measured on every incoming consignment of clay.
Bentonite is added to a ceramic body in small quantity in order to
Your Answer : (Not Answered)
Correct Answer : C
A per cent or two transforms the workability of an otherwise short body, which is why it is used with non-plastic materials. More than that raises the drying shrinkage to a point where cracking becomes difficult to control.
Illite differs from montmorillonite in that illite
Your Answer : (Not Answered)
Correct Answer : D
The interlayer potassium is not readily exchanged and holds the layers together, so illite swells much less than a smectite. It is a common constituent of ball clays and of many brick clays. Its moderate exchange capacity sits between the other two minerals.
Assertion (A): A clay slip can flocculate into an open structure even though all the particles carry a net negative charge.
Reason (R): The edges of the particles can be positively charged and attract the negative faces.
Your Answer : (Not Answered)
Correct Answer : C
Both are true and the reason resolves the apparent contradiction: attraction between edge and face builds the card-house arrangement that traps water and gives a flocculated slip its high viscosity. Deflocculants work by suppressing exactly this edge-to-face attraction.
Marks
Total number of questions : 20
Number of answered questions : 0
Number of unanswered questions : 20