We have developed a coating for power generation turbine blades to increase their durability by improving their resistance to erosion from hard particles and high speed water droplets. The Hardide coating provides a combination of properties not found in traditional coating methods, including TiN and thermal spray tungsten carbide.
Hardide CVD technology is not line-of-sight. This means that the entire blade can be coated uniformly, so that the coating accurately follows the highly-engineered 3-dimensional blade shape and there is not the need for post-coat grinding. The coating as applied has good surface finish but if necessary can be polished further to minimise gas friction. In operation, the blades of steam turbines are constantly bombarded by small water droplets that strike the blade surface at very high and sometimes supersonic speeds. The impact of the droplets causes severe Liquid Impingement Erosion (LIE) making the blade surface increasingly rough and changing its shape. Industrial Gas Turbines can suffer from blade erosion by solid particles, such as dust, soot or scale, which also change the blade’s shape and surface finish. Both water droplet and solid particle erosion gradually reduce turbine efficiency and increase fuel consumption rates.
Longer lasting blades not only reduce maintenance costs (which can be very high for the large power plants), but allow substantial fuel savings and a reduction in the emission of greenhouse gases.
Hardide coatings are also cobalt-free which is an important advantage for nuclear applications where cobalt-containing alloys and hard-facing can be hazardous.