To improve the simulation of the rubbing condition between the seal coating and the blade, the coating andblade sample materials used in this experiment must be consistent with the actual engine. The coating sample was an Al-hBN coating, which was sprayed on a 0Cr17Ni4Cu4Nb stainless-steel substrate using a METCO9MC plasma spraying equipment. The substrate size was20×40×2mm. Before spraying,a NiAl bonding layer was deposited on the substrate to improve the bonding strength between the coating and the substrate. The final thickness of the NiAl bonding layer was 0.1-0.2 mm, and the final thickness of the Al/BN surface layer was approximately 2.5 mm. The composition and mass percent of the coating powder was 75% Al,20% BN and 5%Na2SiO3. The micro-morphology of the coating powder is shown in Fig.1(a). The main spraying process parameters were as follows: argon flow rate of 2.5 m3/h, hydrogen flow rate of 0.2 m3/h, powder delivery rate of 45 g/min and spraying distance of 130 mm. The section microstructure of the as-sprayed Al-hBN coating is shown in Fig.1(b); the coating was mainly composed of metallic phase Al, solid lubrication phase BN and pores.
The blade sample was made of a TA11 titanium alloy and processed by electrosparking into the required installation shape and size. The final rubbing surface with the coating was a rectangle of 20×2 mm.
Fig.1 Micro-morphology of the coating powder(a) and metallography image of the coating section(b)
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