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KEY WORDS

Sink roller, renovation, thermal coating, HVOF technology, wear resistance.

ABSTRACT

The paper deals with failure analysis of sink rollers used in hot-dip galvanizing of steel sheets. It presents the possibility of renovation the surface of the roller using thermally sprayed coatings. The paper contains results of research focused on quality evaluation of three coatings applied using HVOF technology - WC-Co, WC-NiMoCrFeCo and Co-MoCrSi. There was also investigated impact of sealing agent - boron nitride used for sealing the coating on corrosion rate of the coating. HVOF coatings were subjected to metallographic study with aim to study the structure, thickness, mechanical anchoring and hardness of coatings. There was also realised EDX analysis of chemical composition of coatings. Adhesion of coating was investigated in dependence of thermal cyclic loading. Main part of paper is focused on determining wear resistance of coatings by pin-on-disc in 1M NaCl solution and corrosion rate by Tafel analysis. Experiment confirmed that sealing coating WC-Co with boron nitride improves corrosive resistance of the coating. The boron nitride seals the pores in the structure of coating and thus prevents the formation of corrosion and subsequent depreciation of coating in various corrosive environments. Based on reached results, coatings for renovation rollers surfaces can be recommended according to preferred priority. If corrosion resistance of rollers plays key role, WC-Co coating sealed with boron nitride can be recommended together with WC-NiMoCrFeCo coating and the Co-MoCrSi. If the main priority is wear resistance of roller, unsealed WC-Co coating or alloy Co-MoCrSi coating can be used.

CITATION INFORMATION

Acta Mechanica Slovaca. Volume 19, Issue 4, Pages 14 – 21, ISSN 1335-2393

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  Possibilities of Utilization Thermally Sprayed Coatings in the Field of Sink Rollers Renovation

REFERENCES

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