Enhanced Erosion Protection of TWAS Coated Ti6Al4V Alloy Using Boride Bond Coat and Subsequent Laser Treatment

Abstract

The material commonly used in low-pressure high-rating super critical/ultra super critical steam turbines as well as guide and moving blades of high speed aero compressors is Ti6Al4V alloy. These blades are severely affected owing to erosion which leads to drop in efficiency and increase in maintenance cost. This article deals with SHS 7170 coating on Ti6Al4V alloy using twin wire arc spraying (TWAS), enhancing its bonding by providing a thin bond coat and then treating with high-power diode laser (HPDL). Significant improvement in erosion resistance of this multilayer coating has been achieved because of the formation of fine-grained micro structure due to rapid heating and cooling rates associated with the laser surface treatment. After laser surface treatment, the fracture toughness of this multilayer has improved manifold. The water droplet and particulate erosion test results along with the damage mechanism are reported and discussed in this article.

Liquid–Solid Impact Mechanism, Liquid Impingement Erosion, and Erosion-Resistant Surface Engineering: A Review

“…Protection of a TWAS-coated Ti6Al4V alloy using a boride bond coat and subsequent laser treatment was the subject of a similar work by the same research group [265]. This work was an effort to overcome the difficulties in TWAS coatings adhesion to the titanium alloy, as, according to the authors, without this layer it would not be possible to bond the TWAS SHS 7170 coating to the Ti6Al4V alloy.…”

Slurry Erosion–Corrosion Characteristics of As-Built Ti-6Al-4V Manufactured by Selective Laser Melting

“…Thanks to these advantageous characteristics, Ti-6Al-4V has emerged as a powerful alloy for a wide field of applications. In addition to its wide use in surgical instruments and medical implants, it is currently used as a material for aerospace components (i.e., engine compressor blades and disks and helicopter rotor blades) [ 7 , 8 , 9 ], marine and offshore components (i.e., marine ship hulls, propellers, tubes, and shells) [ 1 , 10 , 11 ], oil and wastewater systems components (i.e., valves, pipelines, pipe fittings, and pumps) [ 12 , 13 , 14 ], hydropower plant components (i.e., turbine blades, pumps) [ 15 , 16 , 17 ], and architectural cladding and roofing [ 11 ]. These components are typically exposed to slurry erosion, where the working surfaces are continuously impacted by a stream of a slurry mixture.…”

“…Casting, forging, machining, joining, and powder metallurgy are the dominant conventional processing techniques of Ti-6Al-4V [ 18 , 19 ]. Slurry erosion on conventionally processed Ti-6Al-4V has been studied by several authors under different conditions over the years [ 13 , 15 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. The general outcome of all studies has been poor erosive wear resistance of Ti-6Al-4V, and it is recommended that hardness and yield strength should be enhanced to increase the erosion resistance.…”