Why could someone have a dispersion in the measured hardness or reduced elasticity modulus data? And what is the effect of the grain size (case of ceramic sample) on the obtained values?
The microsture of the ceramic materials which will also be comprised of defects such as voids will effect the hardness/modulus values. The non-homogenity in these mechanical properties is directly related with the local microstrucutral paramters which obviously is depenant upon the manufacturing process.
Thank you for the answer, actually in our ceramic material, based on different TEM observations and density data, we assume that residual porosity should be very small. Does the micro-sized crystals have any impact?
A dispersion was observed in the values of ceramics but not for the glass. But a considerable increase in the hardness and reduced elasticity modulus was observed for the ceramic sample.
This is quite normal in case of ceramic composites and depends on the reinforcements i mean particle, fibers, graphene or nnaotubes. As it is not clear that the grain refinement is due to second phase and what is second phase. If it is pure ceramic then what process was used to refine the grain size i.e sinetring techanique. Grain size of the creamic material is very important and can significantly effect the mechnical properties. Hardness normally increases with decreasing grain size.
You can look some of my papers I. Ahmad et al. / Wear 269 (2010) 71–78, where you can see the results of decreasing modulus with the grain szie reduction. I still appreciate your question because it is very complex to explain the behaviour of ceramics in strcture/properties relationship. Several other factor may also contribute in altering the mechanical properties, which may be beyond the exiting literature. Kholoud..keep this healthy discussion continue please. Please donot hesitate to write or contact.
@Iftikhar
Dear Dr. Iftikhar, i have not gone thorugh your paper, however, reading your last two post it becomes apparent that with the decrease in grain size, the hardness increases and modulus decreases. I am trying to understand this phenomenon. Is is related to the grain boundaries? Because as normally what is observed is that both hardness and modulus are interrelated and follow similar trend. Does both the hardness and modulus decresed in your case? If it is so then, then it can oviously be concluded that the manufactuirng prosess which controls the microstrucure and hence the mechanical properties are responsible for this behaviour.
Kindly elaborate, your experience.
- Badges
- Science topic
- Similar topics
- Comment