Asheet of steel 3-mm thick has nitrogen atomospheres on both sides at 900 c and is permitted to achieve a steady-state di usion condition. the di usion coecient for nitrogen in steel at this temperature is 1: 85 m2=s, and the di usion ux is found to be 1: 0 kg=m2s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 2 kg=m3. how far into the sheet from this high-pressure side will the concentration be 0.5 kg/m3? assume a linear concentration profile.

Steel is coated with a thin layer of ceramic to protect against corrosion. what do you expect to happen to the coating when the temperature of the steel is increased significantly? explain.

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

Draw the engineering stress-strain curve for (a) bcc; (b) fcc metals and mark important points.