Influence of the frequency and flow rate of a pulsating water jet on the wear damage of tantalum

Abstract

The present study focuses on the hydrodynamic erosion of tantalum in the form of the disintegration depth when exposed to periodic impingements of water clusters. Discrete water clusters were generated using a pulsating water jet at excitation frequencies of 20 and 40 kHz to modulate the continuous jet into a pulsating jet. The influence of the technological parameters, such as the excitation frequency (20 and 40 kHz), supply pressure (20, 30, and 40 MPa), nozzle diameter (0.3 and 0.5 mm), and time exposure (0.25-128 s), on the erosion depth of tantalum was observed. The disintegration depth trend showed a proportional nature with the number of impingements directed to the tantalum surface keeping all other technological parameters constant. An increase in the water flow rate from 0.76 l/min (p = 20 MPa, d = 0.3 mm) to 3 l/min (p = 40 MPa, d = 0.5 mm), reduces the time exposure required for the initiation of disintegration from 4 s (80,800 impingements with f = 20 kHz) to 1 s (40,600 impingements with f = 40 kHz), respectively. The effect of change in the excitation frequency from 20 to 40 kHz was observed in form of an increase in the erosion depth from 1587 to 1762 mu m at p = 40 MPa, d = 0.5 mm, and t = 128 s. The surface morphology observed using scanning electron microscopy revealed erosion features, such as craters, micro-holes, surface upheaving, and tearing, on the tantalum surface. No significant change in the mean micro-hardness values were observed near the periphery of the eroded cavity as compared to original material due to high-density of tantalum which obstruct the propagation of shock waves into the material. The outcome of the study enhances the knowledge regarding the hydrodynamic erosion of high-density materials (rho > 15 kg/mm3) in response to the water flow rate, frequency, and time exposure.