1. Oct 24, 2011

### johnsonb.engr

Hello Everybody,

I would greatly appreciated your help. I have been working this problems for the past couple hours and cant seem to find the answer. I tried Google, and opening up my old text books but to no avail. I could really use some help.

I have sample of tungsten coated molybdenum powder. The material is 20% Tungsten by volume and 80 % Molybdenum by weight.

the density of Tungsten = ρw=19.25 g/cm^-3
the density of Molybdenum = ρmo=10.28 g/cm^-3

Obviously ρ=M/V(eqn 1) and Vtotal= Vw + Vmo (eqn 2)

If the material is 20% W by volume, then Vw=0.2*(Vtotal)

Therefore; Vtotal=5Vw

and using eqn 2: 5Vw=Vmo + Vw

4Vw=Vmo

using eqn 1: ρ=M/V; V=M/ρ

And by plunging ρ I obtain,

Vw=Mw/19.25
Vmo=Mmo/10.28

Therefore; 4(Mw/19.25)=Mmo/10.28

Which equals Mw=0.468Mo-------> which makes since because the density of W is ~2x of that of Mo.

However, this is where I am stuck, how do I find the % mass from here using?

FYI....I am trying to solve this theoretically....if this helps the powder I have is 20 % by mass w, has and has an apparent density of 3.0 g.cm^3. Also, when I subjected this powder to a hand held XRF gun, I obtain 94 % Mo and 6 % W.