[Aqualist] Strange happenings with LOI

[Peter Almond]

Alison

Below is a message from head of our analytical services section. I would 
concur with David Wheeler that you seem to be using an inappropriately 
high temperature for LOI. 

Peter

------- Forwarded message follows -------
From:           	"Cresswell, Roger Joseph" 
<Cresswer at lincoln.ac.nz>
Organization:   	Lincoln University
To:             	"Peter Almond" <ALMONDP at lincoln.ac.nz>
Date sent:      	Fri, 06 Jun 2008 08:31:46 +1200
Subject:        	Re: (Fwd) [Aqualist] : Strange happenings with 
LOI
Priority:       	normal

Hi Peter,
   I have heard of stainless steel flaking before.
I think it's something to do with certain grades of stainless that when 
repeatedly heated above ~900 C the chromium oxide layer can become 
brittle and crack, letting oxygen react with the iron and chromium forming 
chromim/iron oxides that can flake off the stainless steel surface. Not sure if 
that explains the white colour though? I guess a metallurgist would be 
familiar with the process?

I'm not sure where I read this now or the context. We use stainless trays 
here, but we only do the first steps at around 500-550 C. 

Hope that helps,
  Roger.

__________________________________________________________

Roger Cresswell
Analytical Services Manager
Agriculture & Life Sciences Division
PO Box 84
Lincoln University
Lincoln 7647

Email  cresswer at tui.lincoln.ac.nz
Phone (03) 3252 811 ext 8238
Fax    (03) 3253 607

------- End of forwarded message --------- 
Peter Almond
Senior Lecturer
Soil and Physical Sciences Group
Division of Agriculture and Life Sciences
PO Box 84
Lincoln University 7647
New Zealand


ph 64 3 3252 811
fax 64 3 3253 607