Slide 1: Influence of Super Reactive Alumina on Rheological Behavior of Free Flowing Castables
Our know-how for your safety Influence of Super Reactive Alumina on Rheological Behavior of Free Flowing Castables at Low and High Shear Rate Nabaltec: a leading supplier of eco-friendly Christian Dünzen, David Janousch flame retardant fillers and specialty alumina Unitecr 2022 1
Slide 2: Abstract
Abstract The rheological behavior of refractory castables is often only described by the simple spreading test. However, castables with very low water contents are well known to exhibit a strongly dilatant behavior, even though the viscosity at high shear rate is usually not measured. The study desc
Slide 3: How to get the full article
How to get the full article Ch. Dünzen, D. Janousch, R. Dirscherl INFLUENCE OF SUPER REACTIVE ALUMINA ON RHEOLOGICAL BEHAVIOR OF FREE FLOWING CASTABLES AT LOW AND HIGH SHEAR RATE Proceedings of the UNITECR 2022 This UNITECR 2022 paper is an open access article under the terms of the Creative Commons
Slide 4: Table of Contents
Table of Contents Introduction – Viscosity Eperimental procedure – Measurement setup – Raw Materials Results and Discussion – Effect of Super Reactive Aluminas – P-t-Plots Summary Outlook 4 4
Slide 5: Introduction - Viscosity
Introduction - Viscosity Shear thicking Shear stress τ (dilatant) Newtonian Shear thinning (pseudoplastic) Shear rate is well defined and constant in the . measurement container. Shear rate γ Hardly appliccable for refractories 5 5
Slide 6: Experimental procedure – Measurement setup
Experimental procedure – Measurement setup Viscosity at low(er) shear rate: Viscosity at high(er) shear rate: – Flow spread – Mixer Power consumption monitoring Conclusions to be drawn about viscosity Flow spread is inversely (!) proportional to viscosity Relevant for real usecases Mixin
Slide 7: Experimental procedure – Raw Materials
Experimental procedure – Raw Materials 100 CPFT [%] 10 1 0,1 0,1 1 10 100 1000 d [µm] Example Test castable Modified Ideal Andreassen (Andreassen) Gap filling effect of Micro-filler Maximization of packing density Particle sizes 2 µm to <<1 µm Reactive Alumina vs. Silica fume 7 7
Slide 8: Experimental procedure – Raw Materials – Monomodal Reactive Aluminas
Experimental procedure – Raw Materials – Monomodal Reactive Aluminas RA SRA 100 NABALOX ® NO 625-10 NO 713-10 RF 80 Distribution [%] D10 [µm] 0.62 0.19 D50 [µm] 2.32 0.85 60 SRA D90 [µm] 5.9 4.4 40 RA Sspec (BET) [m²/g] 1.5 7.6 Na2O [%] 0.1 0.08 20 Al2O3 [%] 99.8 99.7 0 0,1 1 10 100 Grain size [µm]
Slide 9: Experimental procedure – Raw Materials – Test castable
Experimental procedure – Raw Materials – Test castable Tabular Alumina 3 – 6 mm [%] 24 Tabular Alumina 1 – 3 mm [%] 16 Tabular Alumina 0.5 – 1 mm [%] 15 Tabular Alumina < 0.5 mm [%] 7 Tabular Alumina < 0.3 mm [%] 5 Tabular Alumina < 325 # [%] 12 Calcined Alumina 3.5 µm [%] 5 RA 2.3 µm [%] (1-x)·13 S
Slide 10: Results and Discussion – P-t-Plots
Results and Discussion – P-t-Plots 2 4 1600 P [W] 1400 Pmax: Mixer power consumption at Maximum (2) 1200 3 5 Pmin: Mixer power consumption at Minimum (4) 1000 1 Pend: Mixer power consumption after 12 minutes 800 600 tmax: Mixing time to Maximum (2) 400 tmin: Mixing time to Minimum (4) 200 Fmin: Flow
Slide 11: Results and Discussion – Effect of Super Reactive Alumina
Results and Discussion – Effect of Super Reactive Alumina 1600 P [W] 1400 1200 x Mixing behaviour 1000 800 0 Like dry powder 600 400 0.05 Like dry powder 200 0 0.1 Turns into a consistent mass after 6 min 0 120 240 360 480 600 720 t [s] 0.2 x 0 0.05 0.1 0.2 0.35 0.35 Effects 1600 P [W] 0.4 occur 140
Slide 12: The three parameters t, P and F as a function of x
The three parameters t (time), P (mixer Power consumption) and F (Flow spread) tMax and tMin as a function of x PMax, PMin and PEnd as a function of x FMin and FEnd as a function of x 720 1600 P [W] 1400 t [s] flow spread [%] 600 1200 200 480 1000 150 360 800 600 100 240 400 120 200 50 0 0 0 0.0 0.2
Slide 13: Discussion – Effect of SRA on the shear rate dependant rheology
Discussion – Effect of SRA on the shear rate dependant rheology Shear thicking Shear stress τ 1600 0.1 < x < 0.35: (dilatant) Newtonian flow spread [%] 200 1400 P [W] 1200 – When x increases: 150 1000 800 – The viscosity at low and Shear thinning 100 600 high shear rate decreas (pseudoplastic) 50
Slide 14: Summary
Summary Mixer power consumption monitoring – Reveals numerous aspects of a castables rheology – Can prevent over- (under-) mixing – Can be a development tool to reduce dilatancy Super Reactive Alumina – is a tool to influence castable‘s rheology – Can turn a castable from shear thickening to she
Slide 15: Outlook
Outlook Comparison with real viscosity data Modification of the setup towards variable shear rate Use as a tool for product development 15 15
Slide 16: Thank you for your attention!
Thank you for your attention! Contact: Nabaltec AG Dr. Christian Dünzen Phone: +49 9431 53 417 E-Mail: Duenzen.Christian@Nabaltec.de 16 16
Slide 17: Nabaltec products make many aspects of everyday life safer
Nabaltec products make many aspects of everyday life safer, as well as being eco-friendly and thereby an irreplaceable part of your daily routine. 17