Please, read about pycnometric analysis on: http://en.wikipedia.org/wiki/Relative_density#Pycnometer

Hi. That was a good answer. We often use Archimedes' principle to measure density of any substance without specific shape including powder sample as Dr  Shabalin provided a good link as a scientific tool.

However, employing the pycnometric analysis you must provide the stability of temperature for all your measurements as the instability (or thermal expansion of all the substances, including glass of your pycnometer and working liquid such as toluene in it) is the main source of errors. To do it with plus-minus 0.05-0.1 degrees (otherwise your mesurement error > 1%) is a very difficult problem.

Dear Igor & Laleh,

Thank you for your valuable feedback. I made green compacts (using die press) to evaluate the compact density of powder mixtures, while keeping all of the compact parameters same.e.g starting powder mass, compaction pressure, obtained disk diameter and obtained disk height. I'll adopt the pycnometric methodlogy to compare the results.

Thanks again,

Kind Regards,

Khurram 

Simplest method is pycnometer regularly used for powder materials like cement.There is an automatic pycnometer like Micrometrics etc

The bulk density of a powder is the ratio of the mass of an untapped powder sample and its volume including the contribution of the interparticulate void volume. Hence, the bulk density depends on both the density of powder particles and the spatial arrangement of particles in the powder bed.

Please refer this attachment for more info.

http://www.usp.org/sites/default/files/usp_pdf/EN/USPNF/revisions/m99375-bulk_density_and_tapped_density_of_powders.pdf

Greetings Khurram,

Indeed, pycnometry, as mentioned by Dr. Shablin, is a good way. However, the gas can not reach the closed pores. So, what you will measure will be the density including the closed pores. Then, if you know the theoretical density of your starting material, you can calculate the volume of the closed pores, as well.

Indeed, if your starting particles have also internal pores, as we usually see in carbon or ceramic materials, then you will have a serious challenge to get the right value for density. In the latter case, the best way is to mill the starting powder to very fine sizes in order to open the internal pores and perform once again the pycnometry to get as close as possible to the theoretical density of your starting material.

Regards,

The MPIF standard method is very useful for powder metallurgy. You can use Standard No. MPIF 04  (free flowing powder ) and and MPIF 28/ (Non- free flow powder)  for measurement of apparent density. The Bulk density is very near to apparent density.

For pure single-phase materials, it would be very useful to compare the bulk (pycnometric) density with XRD-measured density as well.

Dr Shabalin has provided a easy and very good link.-

Dear Khurram,

These info may be of help:

Volume 49, Issue 2 (01 June 2006) , pp. 173-182

Porosity analysis of PM materials by helium pycnometry

F. J. Semel; D. A. Lados

Also, the brochures from Micromeritics are quite useful. Try this:

http://micromeritics2.reachlocal.com/?scid=1229585&kw=7895020&pub_cr_id=6234969370

Good luck! Luiza

Standard ISO 697

http://www.powtec.de/download/smg_engl.pdf

As the question was regarding bulk density, gas pycnometers (helium pycnometers) are inappropriate, as is a simple density bottle. Since bulk density refers to the total volume occupied by a known mass of powder (i.e. particles plus voids) under some known (or at least reproducible) packing condition.

Loose packing is best done using a Scott Volumeter. Tapped density is used to measure the minimum volume occupied after a defined number of taps (actually drops) from a predetermined height (often 3mm) have agitated the powder bed and caused it to settle. One must understand that in both cases, powder blends can un-mix due to the movement of the particles and if very fine particles were occupying the voids between larger particles, this un-mixing (segregation) can cause the powder bed to expand!

Simply measuring the density by Archimedes method.

You can use a thin film on the bulk (preweighed) to avoid absorption.

Or you can deduct the weight of absorbed water.