I am using 4000 cP methyl cellulose for aqueous tape casting. Since it gives very viscous solution, I am dissolving it in 1.5 wt% in 98.5 wt% DI water. Still it is a very viscous solution. Because of a large quantity of inherent water coming from the MC binder solution, I cannot use more than 1 wt% binder active matter w.r.t powder in slurry, otherwise the powder settles down on container base and water floats on top and there is no mixing because of a lot of water.
What MC viscosity is better keeping in mind a higher possible weight percent dissolution in water? And in how much weightage should it be dissolved in water and at what temperature?
Since sedimentation of particles is very high, what do you recommend for usage of such sized particles for making a good slurry?
For tape casting of 10 µm powder particles, you need to carefully choose the binder viscosity and its concentration to achieve the desired slurry properties. Here are some general recommendations:
Binder Viscosity: A 4000 cP Methyl Cellulose (MC) is relatively high in viscosity. For smaller particle sizes like 10 µm, a lower viscosity binder may be more appropriate. You can consider using MC with a lower viscosity, such as 1000 cP or even 400 cP, which would make it easier to handle and mix in the slurry.
Binder Concentration: To avoid settling and separation issues, you can start with a lower binder concentration, such as 0.5 wt% binder active matter. You can adjust the concentration based on your specific needs, but the total solids content should be carefully controlled to maintain a stable slurry.
Dissolution: When dissolving MC in water, warm or hot water (around 60-80°C) can be used to help dissolve it more effectively. Slowly add MC to the water under stirring to avoid clumps and ensure proper dispersion.
Particle Dispersion: To prevent sedimentation of the 10 µm powder particles, you can use dispersants or surfactants to improve particle dispersion in the slurry. Proper mixing and ultrasonication can also help in achieving uniform dispersion.
Slurry Mixing: Proper mixing equipment and techniques are crucial for maintaining uniform slurry consistency. Be sure to mix the slurry thoroughly to avoid issues like particle settling or agglomeration.
Rheology Control: Consider adding small amounts of thickeners or rheology modifiers to control the slurry's rheological properties, which can prevent sedimentation and improve tape casting performance.
It's essential to perform thorough testing and optimization for your specific materials and processing conditions. This may involve conducting rheological tests, sedimentation studies, and adjusting the binder concentration and viscosity until you achieve a stable and workable slurry for tape casting.
Thank you so much Mr. Gideon C. Irogbele for your detailed response.
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