Abstract

Thermally-sprayed alumina based materials, e.g., alumina-titania (Al2O3-TiO2), are commonly applied as wear resistant coatings in industrial applications. Properties of the coatings depend on the spray process, powder morphology, and chemical composition of the powder. In this study, wear resistant coatings from Al2O3 and Al2O3-13TiO2 powders were sprayed with plasma and high-velocity oxygen-fuel (HVOF) spray processes. Both, fused and crushed, and agglomerated and sintered Al2O3-13TiO2 powders were studied and compared to pure Al2O3. The coatings were tested for abrasion, erosion, and cavitation resistances in order to study the effect of the coating structure on the wear behavior. Improved coating properties were achieved when agglomerated and sintered nanostructured Al2O3-13TiO2 powder was used in plasma spraying. Coatings with the highest wear resistance in all tests were produced by HVOF spraying from fused and crushed powders.

Highlights

  • Metal components are the basis of engineering applications and constructions and are exposed to wide range of conditions and environments, e.g., in process industries

  • Alumina (Al2O3) and alumina-titania (Al2O3-TiO2) materials are widely used as thermally-sprayed protective coatings against abrasion, erosion, and cavitation erosion wear, e.g., in textile, pulp and paper, and pump industries [2]

  • The coating properties provided by high-velocity oxygen-fuel (HVOF) spraying and nanostructured powder materials, are potential candidates to improve the performance of ceramic coatings in cavitation erosion environments

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Summary

Introduction

Metal components are the basis of engineering applications and constructions and are exposed to wide range of conditions and environments, e.g., in process industries. The coating properties have been improved by the use of HVOF processes, as well as with the development of nanostructured powders for plasma spraying, i.e., agglomerated and sintered powders from nanosized primary particles. The performance of nanostructured plasma-sprayed coatings and HVOF-sprayed ceramic coatings has not been truly compared under abrasive, erosive, and cavitation erosion wear. Some cavitation erosion studies of bulk ceramics have been published [24,25,26], but only few studies concerning thermally-sprayed ceramic coatings [27,28,29] These materials have a brittle structure and lower cohesion, which results in considerably lower resistance against cavitation erosion as compared to, e.g., carbide coatings. The coating properties provided by HVOF spraying and nanostructured powder materials, are potential candidates to improve the performance of ceramic coatings in cavitation erosion environments. Structures and the wear behavior of these coatings were studied under abrasion, erosion, and cavitation erosion wear conditions

Coating Manufacturing
Powder Materials
Characterisation Techniques
Wear Tests
Coating Microstructure
Hardness Measurements
Cavitation Erosion Wear Resistance
Abrasion Wear Resistance
Erosion Wear Resistance
Conclusions
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