Tampere University of Technology

TUTCRIS Research Portal

Effect of nozzle geometry on the microstructure and properties of hvaf-sprayed wc-10co4cr and cr3c2-25nicr coatings

Research output: Contribution to journalArticleScientificpeer-review

Details

Original languageEnglish
Pages (from-to)680-694
Number of pages15
JournalJournal of Thermal Spray Technology
Volume27
Issue number4
DOIs
Publication statusPublished - 1 Apr 2018
Publication typeA1 Journal article-refereed

Abstract

Thermally sprayed hard metal coatings are the industrial standard solution for numerous demanding applications to improve wear resistance. In the aim of improving coating quality by utilising finer particle size distributions, several approaches have been studied to control the spray temperature. The most viable solution is to use the modern high velocity air-fuel (HVAF) spray process, which has already proven to produce high-quality coatings with dense structures. In HVAF spray process, the particle heating and acceleration can be efficiently controlled by changing the nozzle geometry. In this study, fine WC-10Co4Cr and Cr3C2-25NiCr powders were sprayed with three nozzle geometries to investigate their effect on the particle temperature, velocity and coating microstructure. The study demonstrates that the particle melting and resulting carbide dissolution can be efficiently controlled by changing the nozzle geometry from cylindrical to convergent–divergent. Moreover, the average particle velocity was increased from 780 to over 900 m/s. The increase in particle velocity significantly improved the coating structure and density. Further evaluation was carried out to resolve the effect of particle in-flight parameters on coating structure and cavitation erosion resistance, which was significantly improved in the case of WC-10Co4Cr coatings with the increasing average particle velocity.

Keywords

  • cavitation erosion < properties, chromium carbide < feedstock, diagnostics < processing, HP/HVOF < processing, HVAF < processing, HVOF < processing, WC-CO-Cr < feedstock

Publication forum classification

Field of science, Statistics Finland