Which type of hardness measurement, macrohardness or microhardness is proffered for knowing the hardness of polymer nanocomposite with ceramic/metal nanoparticles reinforcement?
dear mahesh
I think both of them are applicable.
below text is derived from a paper in title Microstructure, mechanical response and fractography of AZ91E/Al2O3 (p) nano composite fabricated by semi solid stir casting method
Mechanical properties of the composite with different weight fractions of reinforcements were evaluated in terms of micro hardness, macro hardness and tensile properties. Hardness studies were carried out to study the effect of reinforcement and its quantity on hardness. Micro hardness and macro hardness were evaluated for a load of 100 gf and 10 kg respectively with a loading period of 15 s. The hardness values were measured by taking an average of 8 readings. Tensile testing was done as per ASTM B 557 Standard on UTN 40, FIE machine. Three readings for each composition were noted for tensile testing. Fracture surfaces of tensile specimens were analyzed using FESEM images.
Thank you. It would be appreciated if you can comment on what kind difference is there between the information they provide
Dear Mr. Mahesh,
It depends in what dimensions you have your polymeric nano composite. If it is at least 10mm thick go for macro hardness test, it will provide you the combined hardness of matrix along with particles or reinforcements.
If the specimen is thin that 10mm, use Vickers or Knoop hardness testing which lies under the category of micro hardness. The problem with micro hardness testing is, they are designed for homogenous materials and the probe can miss some particles, consider size of indenter and your added nano particles. I hope this would help.
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