Synergistic effect of Al₂O₃/TiO₂ reinforcements on slurry erosion performance of nickel-based composite coatings

Abstract

Various aspects such as development, experimentation, and analysis have been covered in the present work to examine the behavior of test coatings under slurry erosion. The primary objective of the present study was to establish the specific mass loss from the test coatings under various slurry environmental conditions and highlights the importance of the addition of alumina in improving the slurry erosion resistance of Ni-TiO 2 coating. To attain this objective, two powder compositions, viz. Ni-20TiO 2 and Ni-15TiO 2-5Al 2 O 3 were deposited onto the CA6NM grade hydro-turbine steel using high velocity frame spray process. The microstructural characterization of the coatings was done by employing surface roughness tester, scanning electron microscope/energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques, whereas mechanical analysis was carried out using micro-hardness and bond strength tester. The slurry erosion tests were performed using an indigenously fabricated high speed slurry erosion test rig at different levels of rotational speed, average particle size of erodent, and slurry concentration in order to explore their effects on slurry erosion performance of test coatings. The slurry erosion results, as well as scanning electron microscope observations of eroded specimens, revealed higher slurry erosion resistance of Ni-15TiO 2-5Al 2 O 3 coating in comparison with Ni-20TiO 2 coating. Furthermore, each operational parameter was found to have a proportional effect on specific mass loss in case of both the coatings.

Slurry jet erosion performance of high-velocity flame-sprayed nano mixed Ni-40Al2O3 coating in aggressive environment

“…Also, there may be the combined action of nickel in the softer phase and alumina in the harder face. This case is similar to the previous literature 1,7 work subjected to slurry erosion test on the as-sprayed Ni-Al 2 O 3 coating. Figure 15 shows the trend of volume loss for as-sprayed and un-coated specimens recorded run under different experimental conditions.…”

“…slurry concentration (SC), impact velocity and size of erodent particles, were selected which significantly contribute to the erosion of the steel. 1,7,23,24 Kumar Goyal et al 25 proposed an experimental relation to predict the erosion rate of the steel where V , D , C are the velocity, diameter of erodent and silt concentration, respectively. α , β , γ are the constants depending upon the type of erodent particles and targeted material.…”

“…In the severe condition when the water-silt concentration goes beyond the acceptable limit of 5000 ppm, plants need to shut down for the maintenance activity. 1 Particle velocity, impingement angle, concentration, hardness, and shape of erodent are some responsible factors which deteriorated the turbine components thereby affecting the performance. 2 Mann and Arya 3 give an estimation of 120–150 million US$ loss incurred every year due to the erosion caused by sedimentation.…”

Insights to improve the tribo-performance of materials used under slurry erosion applications: A review

“…66 Many authors have applied Taguchi method in their investigations. 8,9,14,27,31,36,57,58,66,[83][84][85][87][88][89][90][91][92] Some authors used the full factorial method for carrying out a suitable number of experiments. 93,94 Related to various researches, many authors 1,2,9,15,20,45,50,53,63,75,77,82,[94][95][96][97][98][99][100][101] discussed the surface morphologies of different materials posterior to SE testing, exhibiting the different mechanism of failure on the observed eroded surface.…”

“…66 Many authors have applied Taguchi method in their investigations. 8,9,14,27,31,36,57,58,66,83–85,87–92 Some authors used the full factorial method for carrying out a suitable number of experiments. 93,94…”