Using Gas Detonation Spraying to Improve the Service Life of Gas Turbine Blades

       The gas turbine blade is made of heat-resistant alloy, and the hardness of the substrate is HV500. Gas turbine blades work in an environment of 870°C, and are corroded and scoured by high-temperature combustion products of kerosene. Please select suitable spraying materials and processes to pre-protect the gas turbine blades and improve the service life of the blades.



    1) Spray material

    When the temperature exceeds 500 °C, the wear resistance of Co-based WC coatings decreases significantly due to WC oxidation. In the range of 500 ℃ ~ 980 ℃, the NiCr/Cr3C2 coating is quite suitable, and this type of coating has good wear resistance in the above temperature range and aggressive media. Therefore, NiCr/Cr3C2 type spray powder is selected.

    2) Spraying method

    NiCr/Cr3C2 coatings can be prepared by gas detonation spraying or plasma spraying; in this example, the gas detonation spraying method is preferred for spraying.

    3) Spraying process

      (1) Cleaning. Clean and degrease the surface to be sprayed.

      (2) Sandblasting. Use corundum sand with a particle size of 20 mesh to 40 mesh to blast the processing parts, cover other parts, and spray them immediately after blasting.

      (3) Spraying. The process parameters are as follows:

         C2H2:O2=1.1:1.2

        Oxygen pressure 0.4MPa; Acetylene 0.15MPa

        Deflagration frequency: 4 times/s

        Powder spraying speed: 1.5kg/h~2.1kg/h

        Spraying time: 6min

        Coating thickness: 80 υm ~100υm

     (4) Post-processing. Diamond grinding; surface roughness Ra: 1.25 .

     (5) Coating properties. Coating hardness HV1100~1300; bonding strength 60MPa; porosity < 1%.

     (6) Use effect. Spraying NiCr/Cr3C2 type material on the surface of gas turbine blades increases the service life by 5 times.