Cavitation Erosion Properties of HVOF Sprayed WC Cermet Coatings

摘要

Relations between mechanical properties and cavitation erosion (CE) properties of the WC-cermet coatings were investigated. WC-Cr3C2-Ni, WC-CoCr and WC-Co coating specimens with different porosities for each material were prepared by a HVOF spray method. Mechanical properties of the coatings were evaluated by a Vickers hardness test and a SUGA abrasion test. In addition, CE tests using an ultra-sonic vibrator and observations of an eroded coating surface as well as particles of the coating collected from a water tank after each CE test were carried out. As a result, it was found that the CE properties were sensitive to the porosity of the coating, especially for WC-Cr3C2-Ni and WC-CoCr coating, even though the results of the hardness and the abrasion tests were insensitive to the porosity. This result shows that the porosity of the coating is one of the key control point for its CE resistance and a densification of the coating is important against CE problems.