Silicon Powder Properties Produced in a Planetary Ball Mill as a Function of Grinding Time, Grinding Bead Size and Rotat
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ORIGINAL PAPER
Silicon Powder Properties Produced in a Planetary Ball Mill as a Function of Grinding Time, Grinding Bead Size and Rotational Speed Benedicte Eikeland Nilssen 1,2 & Rolf Arne Kleiv 2 Received: 18 June 2019 / Accepted: 25 November 2019 # Springer Nature B.V. 2020
Abstract Mechanical milling is a promising route for production of submicron and nano sized silicon powders, but it is challenging to predict and control the product properties. In this study a metallurgical grade silicon quality was milled in a planetary ball mill and the properties of the powder were investigated as a function of grinding time, grinding bead size (20 mm, 2 mm, 0.25 mm) and rotational speed based on the concepts presented in the stress model. The finest powder was characterized by a d50 of 0.62 μm. This powder was produced with the 2 mm grinding beads and 4 h of grinding (i.e. the highest specific energy input to the mill with this bead size). The largest BET specific surface area, the highest concentration of iron contamination and the smallest amount of crystalline silicon phase were characterized in the powder produced using the 0.25 mm grinding beads and 4 h of grinding (i.e. the highest stress number). Aggregates consisting of silicon and iron were formed. An acid wash to reduce the concentration of iron contaminant revealed that silicon did form an amorphous phase as well as the specific surface area increased. With a constant specific energy input to the mill, a reduction in rotational speed (i.e. reduced stress energy) produced similar powder properties with the exception of the particle size distribution. Keywords Silicon powder . Submicron particles . High energy ball milling . Planetary ball mill
1 Introduction Silicon powders in the submicron and nano size range attain more interest in various scientific disciplines due a constant improvement of existing technologies as well as an increased number of new and potential applications relying on the chemical and physical properties of silicon. Silicon is also an interesting material due to its natural abundance and low toxicity. Applications of silicon and silicon containing powders include ceramic materials [1, 2], electronic devices [3, 4], solar cells [5], medical applications [6–10], catalyst for reduction of carbon dioxide [11], thermoelectric materials [12], additive
* Benedicte Eikeland Nilssen [email protected] 1
Elkem ASA, Technology, Fiskåveien 100, 4675 Kristiansand, Norway
2
Department of Geoscience and Petroleum, Norwegian University of Science and Technology, S. P. Andersens veg 15a, 7031 Trondheim, Norway
manufacturing [13], production of hydrogen gas to fuel cells [14, 15], and active anode material in lithium ion batteries [16–18]. Each of these applications have certain requirements to the physical and chemical properties of the powder, including particle size, particle shape, concentration of contaminants, amount of amorphous phase, and specific surface area. For the producers of such powders it is important to understand
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