Material Selection for Blender Blade

[Bunt23]

I'm looking for some help selecting a material for what's called a Rushton Turbine impeller (if you do a quick google search, you'll see it). The application is to mount the impeller to a motor shaft and use it to blend soil and water to make a slurry to use for soil analysis. We've currently been using one that is 316L SS, and we find that the blade wears very quickly (after only 500 cycles, it had shed 5% of its mass). So I'm thinking we need a harder material, but I'm not a materials expert, so I was hoping for some help. As I said, it will be used to blend soil with water at 3450 RPM speed, and so it is a very abrasive application. Any suggestions on a better material to use? Thank you!!

 

[Compositepro]

You are probably using an inappropriate design to start with, for what you are trying to accomplish. A useful logical technique is to ask yourself, "how would I design a blade so that it wears as quickly as possible?". If you come up with the same design, maybe something is wrong.

Media mills and ball mills are designed to do what you are doing. Borrow from those designs, and their material choices. There are many subtleties to these designs, but the basic concept is that the soil itself is used to grind the soil. The agitator is used to put energy into the soil in in the least abrasive way possible. Of course, the slurry concentration is one of the most important factors, which you have not mentioned. Generally, one should start with a high concentration (like 50% solids, or more) and then dilute as needed. For example, a laboratory procedure would use a mortar and pestle to make a paste, which is then diluted with water by shaking in a test tube.

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