Thread: Chromium Oxide 1.0?

Who knew my newbie confusion would spark such a great discussion

It's been and enjoyable learning experience watching this post grow.
Justin

Originally Posted by Lesslemming

There is no way of changing Cr2O3 to Cr2O5
It simply does not exist.
Chromium has exactly 3 arms. He can grab 3 things.
Oxygen has 2 arms.
So if two chromium will grab five oxygen there will be some arms left
to grab something. This is not possible.
There are exceptions of course but for explaination purposes it will do.

Cr203 to chr205 is just example . i mean early in the message . it tried to simplify but you guys going to deeper and deeper. did you read diamond and graphite example early in the post?
if you want to start chemistry then this post will be useless 90 people will not understand what we are saying.

Example is this . what will help if i say this words.
chemical composition, which is 55.4% chromium, 42.5%
oxygen, and 2.1% hydrogen. ?
will this help or bring more confusion?

Sorry Hibud; but there is just NO WAY this will happen.
Chromium oxide (Cr2O3) will always consist in 2:3 "Cr" to "O"
There is no Hydrogen in it (except for impurities that we would have to leave out or it would unnescessarily get waaaaay too deep)
So you can be 100% sure in Chromiumoxid you will ALWAYS have
40% Chromium
and 60% Oxygen
Trust me, I know

This isn´t that deep in chemistray at all.
Chromium oxide forms crystalls. These crystalls consist of many Cr2O3´s
no single O´s or Cr´s.
Solidly bond Cr2O3´s

The easyest way to say this for everybody:
The size of chromium oxide is just as variable as this of diamond and aluminiumoxide.
All of them are availiable in nearly any particle size.
But Cr2O3 is just harder to find in specific sizes.

After having a little chat with Hibud I know where the difficulties where.
He didn´t want to explain why Cr2O3 would always be the same size,
he wanted to point out that the explaination why it actually can be
is way too complicated. I am sorry I didn´t understand it right away,
but just like him I have some difficutlies with the english language

So I think the simplest explaination would be:

Chromium Oxide forms crystalls that can be of different size.
Cr2O3 will not always be 0.5µ and there are many other sizes.
The higher the quality, the smaller the particles.

In germany we stick to professional acrylic colors for artists.
There are standatized pigment charts.
The pigment we are looking for is PG 17.
Kremer Pigmente published a specific chart on demand
that bartisto has posted (thank you)
http://www.bilder-hochladen.net/files/4aer-2e-jpg.html

there it says the average size of PG17 particles is 0.3µ
and the shape is round (so it has no sharp edges )

This way we know PG17 is the real deal.

There are some other interesting pigments
like PR 101 that would be iron oxide.
I am looking forward to try this one out in the near future

CrOx can be found in different grit sizes, beeing used for cuting, polishing and fine polishing.

The american company Buehler sells both .5 and 1 micron CrOx http://www.buehler.com/

Their product is made for sample preparation in metallography. Probably one of the most technical demanding polishing applications.

Best,
Felipe