i am working on max phase preparation......i am a newly joined PhD scholar. I wanted to make MAX phase of Ti3AlC2 , in most of the literature they are using the metal powder of Ti and Al for the same.But on the container of these metals its mentioned that CATCHES FIRE SPONTANEOUSLY IF EXPOSED TO AIR.....also no such precaution for the same has been mentioned by the author of most of articles....can anyone tell me about this?? Thanks in advance
@ Sameer Seth
I am also in the MAX phase preparation. Usually we can mix these powders of particular molar ratios by dispersing them in suitable organic solvents such as ethanol, isopropanol, etc...
Pyrophoric materials (ones that spontaneously combust with O2 in air) MUST be handled in an air-free environment to be done safely. An inexpensive way to do this is with a nitrogen filled glove bag (https://aprilabbott.wordpress.com/2019/11/11/diy-glove-bag/). Also as the other researcher mentioned, once the powders have been dispersed in a suitable solvent they should be safer to handle under standard lab safety conditions.
Please take note that my comment hereunder is without any legal liability as I am no HSE expert.
As far as I know, neither Ti nor Al micrometer scale powder ignite spontaneously in air at AMBIENT TEMPERATURE, even though there are other metals which do (like some rare earths). (I do NOT know about Ti or Al nano-powders.)
Usually, the risk of metal powders is measured in two criteria: a) amount of activation energy (=temperature of spontaneous fire), b) reaction speed (=speed of spread of fire). Al and Ti are very hazardous in b) but not so hazardous in a).
Al and Ti micro-powders require both a thermal activation energy, such as increased temperature or a spark. That means that you can handle both powders in air, but you need to keep a tidy laboratory because metal dust films are dangerous in case of an unintended spark or ignition (secondary dust explosion).
For dust cleaning - you cannot use a normal vacuum cleaner but a special ATEX-proven vacuum cleaner, because electrical sparks and heat cannot be excluded inside a normal vacuum-cleaner. Or you use a wet pad for cleaning laboratory surfaces (instead of vacuum-cleaning).
If you handle them in the glove box (under N2 or Ar), you need to be tidy also, otherwise the problem is only delayed to when you aerate the glove box, for example for rearranging equipment in there.
There is another hazard source, though, when mixing Al and Ti: they will form the intermetallic compound (like Ti3Al or TiAl) in an exothermal reaction. You need to do it at suitably slow reaction rate in a device suitable for heat removal.
Thank you sir Laurenz Plöchl Peter Kracke B. Srikanth Ragunath and T. Yanko for kind answers.....but still I am in confusion whether to use these metal powder in air or in inert atmosphere.
B. Srikanth Ragunath so do you mix these powders in inert atmosphere or in air??
Sameer
It is a tricky situation and depends upon the pyrophoric nature of powder particle size of the powders being handled. Organic solvent such as ethanol has been used in mixing pyrophoric powders in a residual oxygen free helium or argon atmosphere. However, if you take very thin strips of Ti and Al and chop it down to fine pieces in a protective atmosphere and then melted down in arc furnace in vacuum with oxygen getter, try it, and the alloy will be made. In my younger days I used to make such alloys for professors - Cyril Smith and Barrett at the Institute for Study of metals, University of Chicago. Talk to your supervisor on this, and be careful in handling the powders. Good luck.
Prof Dr. K
- Badges
- Science topic
- Similar topics
- Geoscience
- Atmospheric Sciences
- Atmosphere
- Air