Study of CVD Coated and Uncoated INCO 718 Exposed to Particulate Flow

Abstract

The major problem confronting developers of coal burning boilers, fluidized beds, and gas and steam turbines, is the serious erosion of the systems’ components by the suspension of fly ash or other solid particles in the flow. A permanent loss of performance is associated with surface erosion, which is caused by particle surface impacts. To improve the resistance of hot erosion and corrosion, new alloys and coatings are investigated. The objective of this research work is to investigate the basic erosion process and fluid mechanics associated with material degradation in coated and uncoated INCO 718. This nickel-based superalloy is frequently used for manufacturing of jet engine and rocket components. Chemical vapor deposition (CVD) technique is used to apply a ceramic coating (TiC) to the INCO 718 superalloy. The erosive wear of the samples is investigated experimentally by exposing them to chromite particle laden flow at velocities from 180 to 305 m/s and temperatures from ambient to 538°C in a specially designed erosion wind tunnel. In addition, the eroded surface is examined by scanning electron microscopy (SEM). The obtained results show the effect of the impingement angle, temperature and velocity on the erosion rate. The cumulative effects of the impacting particles mass on the weight loss and the erosion rate of the coating are also investigated. This study demonstrates that the tested CVD titanium carbide is a perfect high temperature erosion resistant coating for INCO 718.