Question

COURSE: Material Physics

3. In the process of producing ceramic powder, mesh is often used as a unit of measure for powder. Explain the meaning of the mesh! How do you get powder between 255-400 mesh?

4. Mention the various tests to find out ductile or brittle material! Explain briefly!

Answer 1

3),Two scale are used to classify particle sizes,that are US sieve series and Tylor mesh size. A powders mesh can at times be,A-6 mesh powder contains particles that pass through a 6 mesh screen.A,-6,mesh powder has particle that measure less than 3360, microns. A powder that is -325 mesh has particle that measure less than 44 micron.The larger the mesh number the smaller the particle size of the powder.

4), A material is brittle ,when subjected to stress,it breaks without significant plastic deformation.Actually brittle material are absorbed a very rare amount of energy ,even in the case of high strength.Invluding ceramics and glass and also polymer,some times steels become brittle at low temperature, depending on their composition and processing.

When a material has reached the limit of its strength,its at their extreme of deformation,if it at extreme , fracture becomes the more likely to outcome,and material can be brittle, improving material toughness it act balancing. Normally Brittle material s such as glass are not difficult to toughen effectively.In case there including two process,that is one is absorb the tip of a propagating crack or to create carefully controlled by residual stresses so that cracks from certain predictable sources will be forced closed.Thd first method is used to laminated the glass that is two sheet of the glass are separated by as n interlayer of polyvinyl butyralthat is polymer absorbs the growing crack.And in second one process may toughened glass and pre stressed concrete.