Experimental investigation of fretting wear of coated spring clip and inlet ring in land-based gas turbines at elevated temperature

摘要

The objectives of this investigation were to characterize the friction and fretting wear behavior of coated inlet ring and spring clip components used in land-based gas turbines at elevated (500 degrees C) temperature. In order to achieve the objective, a novel high temperature fretting wear apparatus (HTFWA) was designed and developed to simulate the conditions existing in a gas turbine. Sections of actual inlet ring and spring clip were cut from a gas turbine and used in the test apparatus. The test apparatus was used to investigate fretting wear of APS sprayed Cr3C2-NiCr (25% wt.), HVOF sprayed Cr3C2-NiCr (25% wt.), HVOF sprayed T-800 and APS sprayed PS400 coated inlet rings against HVOF sprayed Cr3C2-NiCr (25% wt.) coated spring clip. Fretting wear experiments were conducted with normal loads up to 400 N at a fixed displacement amplitude of 0.5 mm and frequency of 5 Hz. A proximity probe was used for in-situ wear depth measurement at the spring clip and inlet ring contact pair. The results indicate that the combination of PS400 coating on inlet ring and HVOF Cr3C2-NiCr on spring clip wear the least as compared to other combinations in both running-in condition and under steady state regime. PS400 also demonstrated a 50% reduction in coefficient of friction as compared to other coatings at 500 degrees C. Further, a theoretical approach was developed to estimate the evolution of wear depth with sliding distance for a cylindrical contact configuration using Archard's wear law. The experimental and theoretical results were found to be in good agreement with each other.