Gas Explosion Spray Repair of Air Turbine Turbine Blades

       The anti-vibration flanges of turbine blades of aviation gas turbines often fail due to the combined action of corrosion wear and a certain impact load during operation. There are a batch of failed turbine blades, and the wear depth at the anti-vibration flange is about 250υ m. Please choose appropriate spraying materials and processes to repair and strengthen the blades.



    1) Spray material

    According to the working conditions and failure mechanism of turbine blades of aviation gas turbines, 80WC-20Co spray powder with good anti-abrasion performance and good strength and toughness matching is selected.

    2) Spraying method

    It can be seen from the Co-WC binary phase diagram that at 1340 ℃, there is a γ+WC eutectic mixture (γ phase is the solid solution of W and C in Co). The decomposition temperature of WC is 2775 ℃, and the melting point of W2C is 2800 ℃. Therefore, when the tungsten carbide-based coating is sprayed, the tungsten carbide will decompose and oxidize. In the range of 600℃~2000℃, both C and W will oxidize to generate CO2 and WO3. Due to the loss of C, the coating will be adversely affected. It is for the above reasons that the performance of tungsten carbide coatings prepared by gas explosion spraying is better than that of plasma coatings. Therefore, the gas explosion spraying method is preferred for spraying.

     3) Spraying process

     (1) Preprocessing. The wear parts at the anti-vibration flanges are processed to a depth of 300υm.

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

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

     C2H2:HO2=1.1:1.2

     Oxygen pressure 0.4MPa; Acetylene 0.15MPa

     Deflagration frequency: 4 times/s, ,

     Powder spraying speed: 3.6kg/h~4.2kg/h

     Spraying time: 15min

     Coating thickness: 350NiCr/Cr3C2

    (4) Post-processing. Diamond grinding; surface roughness Ra: 0.63υm.

    (5) Coating properties. Coating hardness HV950~1100; bonding strength 60MPa; porosity < 1%.

    (6) Use effect. The 80WC-20Co coating is sprayed on the anti-vibration flange of the blade, and the service life of the blade is increased by 3 times.