when i add graphite at three levels to my metal matrix composites, i get the density values initially increases and then decreases with graphite addition.
Alain
I have fixed amount of SiC in all the composites does this have any impact for my change in density of composites
based on rule of mixture, the density of composites certainly reduced with increase of graphite percentage because of low density of graphite (2.25 g/cc)
About density measurement of graphite flakes you may want to check: https://www.researchgate.net/post/How_do_we_find_the_bulk_density_and_particle_density_of_exfoliated_graphite_flaks_in_Lab
It is very difficult to homogeneously mix a small amount of graphite into copper matrix due to the significant difference in density of both constituents. If the amount is too small, the graphite will be most probably acts as lubricant, reducing friction during compaction, as mentioned by Dorota Nagolska. As a result, the density of the composite is increased. As more graphite is added, the mixing homogeneity will increase, thus the density of the composite will decreased as mentioned by Raj Kumar. Based on experience, it is very difficult to add more than 5 vol% of graphite into the metal matrix composites because of the passive nature of graphite. So I think your "3 levels" of graphite contents were not significantly difference. My suggestion is to adjust the graphite content for each level. In order to do so, you might want to introduce surface modification on the graphite.
Hamid Fallahdoost
10 wt% is almost equivalent to 5 vol%, so basically you and I observed the same agglomeration issue. I wonder how do you solve the problem?
About mixture rules that relate the density of a composite with either the mass or volume fractions of its components, or with their ratios, see: https://www.researchgate.net/post/I_have_a_composite_materials_with_the_composition_of_AxByCz_How_can_I_calculate_density_of_the_composite https://www.researchgate.net/post/composites_may_consists_of_three_different_constituent_like_Epoxy_carbon_and_glass_fiberhow_i_can_calculate_volume_and_mas_fraction_from_density https://www.researchgate.net/post/How_might_I_determine_glass_fiber_content_in_composite
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