Reduction of Wall Friction of Fine Powders by Use of Wall Surface Coatings

Christof Lanzerstorfer,Christian Forsich,Daniel Heim

doi:10.3390/coatings11040427

Christof Lanzerstorfer, Christian Forsich + Show 1 more

Open Access

https://doi.org/10.3390/coatings11040427

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Journal: Coatings	Publication Date: Apr 7, 2021
Citations: 2	License type: CC BY 4.0

Affiliation: University of Applied Sciences Upper Austria

Abstract

In this study, the possibilities for the reduction of powder wall friction by different types of surface coatings on the wall material were investigated. Two conventional coatings, an ultra-high molecular weight polyethylene plate and an anti-friction varnish, were tested, together with a diamond-like carbon coating. It is the first time a diamond-like carbon coating has been researched with respect to powder wall friction reduction. The wall friction angles were measured with a ring-shear tester. The results showed that the conventional coatings did not really reduce wall friction in comparison to structural steel. In comparison to the stainless steel they even increased it. In contrast, the diamond-like carbon coating reduced wall friction significantly. These first results are very promising. However, more detailed investigations are required.

Highlights

Wall friction is an important effect which has to be considered in the design and operation of powder conveying, dosing, and storage equipment
Wall friction depends on the properties of both the powder particles and the wall material
The properties of the powder are mainly defined by the respective production process and means to reduce wall friction are usually limited to the selection of the wall surface material

Summary

Introduction

Wall friction is an important effect which has to be considered in the design and operation of powder conveying, dosing, and storage equipment. Wall friction depends on the properties of both the powder particles and the wall material. Particle size is an important parameter with respect to wall friction. Larger wall friction angles for smaller particle sizes were reported for example for wet gypsum [2] and for fly ash from biomass combustion plants [3]. The properties of the powder are mainly defined by the respective production process and means to reduce wall friction are usually limited to the selection of the wall surface material. An important wall material property for wall friction is the surface roughness of the wall. Larger friction angles were reported for higher values of the wall roughness for salt [5] as well as for polyethylene pellets [6] and limestone powder [7]. Other important parameters of the wall material are its hardness and its chemical composition [1]

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