The best lubricants for a machine working at high temperature & load is_________________?

Related Mcqs:

1. Principal alloying elements of cast tool alloys which have very high wear resistance & high temperature strength are ?

   A. Cobalt, chromium & tungsten
   B. Cobalt, chromium & nickel
   C. Molybdenum, tungsten & chromium
   D. Cobalt, zirconium & molybdenum

2. _______________ is the hardest oxide and is hence used where high wear resistance at high temperature is required?

   A. Beryllium
   B. Zirconia
   C. Alumina
   D. Magnesia

3. High relative humidity decreases the evaporative process and as the temperature is increased, the relative humidity decreases. The comfort range for human body is the ambient temperature of 22 to 27°C with relative humidity ranging from _______________ percent ?

   A. 5 to 10
   B. 15 to 25
   C. 45 to 50
   D. 75 to 80

4. The boiling & freezing points on a newly defined temperature scale in degree ‘D’ are 400°D & 100°D respectively. The temperature reading corresponding to 60°C on this new temperature scale will be equal to _____________ °D ?

   A. 140
   B. 180
   C. 240
   D. 280

5. Heating the Hypo-eutectoid steels to 30°C above the upper critical temperature line, soaking at that temperature and then cooling slowly to the room temperature to form a pearlite & ferrite structure is called_______________________?

   A. Tempering
   B. Hardening
   C. Annealing
   D. Normalising

6. The ratio of thermal & electrical conductivity is same for all the metals at the same temperature; and at around room temperature, this ratio is proportional to(where, T = absolute temperature, °K) ?

   A. T
   B. 1/T
   C. T2
   D. 1/T2

7. High endurance limit of carburised machine parts is because of the fact that carburisation __________________?

   A. Suppresses any stress concentration produced in the parts
   B. Enhances the yield point of the material
   C. Introduces a compressive layer on the surface
   D. Produces a better surface finish

8. Capacity & power requirement for an air compressor working at high altitude compared to sea-level will be_______________?

   A. More
   B. Less
   C. Same
   D. Either more or less; depends on the climatic conditions

9. At 100% relative humidity, the dew point temperature of moist air is_________________?

   A. Less than the wet bulb temperature
   B. More than the wet bulb temperature
   C. Equal to the wet bulb temperature
   D. Equal to the ambient temperature

10. A material is capable of resisting softening at high temperature, because of its property termed as____________________?

    A. Hot temper
    B. Hot hardness
    C. Fatigue
    D. Creep