I need some details regarding the proper use of Archimedes method.
Specifically:
1 To eliminate surface porosity impact on my measurements I need to cover my specimens with wax or lacquer. What commercially available wax or lacquer best fits for such application?
2 Is there a commercially available scale for such experiments?
3 Apparently, the suitable method for my measurements is described in ASTM B962 - 17. However, I do not have access to this standard.
Hello Mikhail,
Is the following video helpful?
"Method for Determination of Compacted or Sintered Powder Metallurgy (PM) Products":
https://www.youtube.com/watch?v=gwRAQaoH73E
Impregnate using oil with a kinematic viscosity of 20-65 cSt at 30 oC...
Dear Mikhail,
the form of an outer surface can be very complex. It is unimportent for the validity of Archimedes law. (If you need, I send you the mathematical evidence). Don't use wax. This falsificates strongly the measurement.
But you must know that you determine the effectice density. The method averages over all cavities. (This is like the average density of a ship (
To access the bulk density of a porous sample by the Archimedes method after coating the sample (e.g. with paraffin) ― Let Δmc be the mass that the coating adds to the sample, originally of mass ms; let ρc denote the density of the coating material, while Vs stands for the bulk volume of the previously uncoated sample. The measured density of the coated sample is: ρ = (ms + Δmc) / (Vs + Δmc / ρc). The Inferred bulk density of the (uncoated) porous sample would be: ρb = ms / Vs = ms / [ms / ρ + Δmc·(1 / ρ - 1 / ρc)].
Please note that bulk volume includes the volume of compact solid material (excluding voids) and the volume of both closed and open pores, while bulk density is the ratio of the sample mass to bulk volume.
Mikhail,
you may use Russian analogs of ASTM B962 - 17, those are GOST 18898 or GOST 25281, according to them you will need paraffin (GOST 23683), if you want to make measurements with covering of surfaces.
Generally, after melting technologies for 3D-printing (SLM, EBM etc.) it doesn't necessary to cover surfaces, it is enough to use the surface-active substances (that you will find in marked above GOSTs as well).
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