We are working on Metal Matrix Composite fabrication using electrolytic grade iron powder of mesh size 100 with CNT powder as a reinforcing agent. We are looking for a suitable binder as we couldn't get a suitable green compact which kept disintegrating(Picture attached) even at 25 Tonnes load. Any other suggestions with suitable sintering temperatures and holding times would be most helpful. Thanks in advance!
You may try using following parameters:
- Use Binder as Kenolube- 0.5 % of mass of Iron powder or Paraffin Wax- 3 % of mass of iron powder or Polyvinyl Alcohol- 3% of mass of iron powder.
- Mix binder with metal powder uniformly before compaction.
- Compaction pressure ranging from 300 Mpa to 900 Mpa with interval of 100 Mpa.
- Generally, sintering of iron powder compacts are done at around 1150 0C (30 min) followed by furnace cooling upto the 550 0C then air cooling.
I have used PVA solution (10% in water, you can increase conc. 15 or 20% if it does not work) as a binding agent and it worked well. I also faced the same problem when I was compacting my samples. You should take care about following
1. Mix the binder thoroughly by mortar pastel and then sieve the powder before putting into the die.
When u are compacting loading rate should b slow.
This problem can exist due to the lubrication of the die also. You should lubricate die with some care.
During the sintering if you are pressureless sintering then you should do slow heating and cooling to get the required temperatures.
This may be an alternative: Binder: 50 % paraffin wax (type "DC7355", source Dussek-Campbell Inc., Chicago,
USA), 30 % polypropylene based polymer (type "Proflow 3000", source Polyvisions
Inc., York, USA), 20 % stearic acid based surfactant and binding agent (type
"Fusabond MD 226", source Du Pont, USA).
My suggestion is, for hard-to-press powder, add stearic acid into alcohol solution and used them as wet binder. Add iron powder into the wet binder and use ball roll mill to mix them together. Use oven for drying. Once dried, add in cnt and perform mixing again. Press as normal, 500 MPa should do it. Have fun!
Hello, please can you tell me if the binder suggestions from above work also with mecanically alloyed Fe14%wt.Cr powders?
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