Method for preparing uniform coating on surfaces of complex molded surfaces by using PS-PVD

Abstract

The invention discloses a method for preparing a uniform coating on the surfaces of a plurality of workpieces with complex molded surfaces at a time by using plasma physical vapor deposition (PS-PVD).According to the technical scheme, the method can realize accurate and uniform preheating of the workpieces to be sprayed, realize uniform heating of all the parts of the complex molded surfaces, andimprove the uniformity of the coating on the surfaces of the complex molded surfaces. By adoption of the method,under the protection action of vacuum and inert gases and under the condition of no deformation and structure change of a workpiece matrix, a relatively high preheating temperature is allowed, so that the temperature difference between coating particles and the matrix can be reduced, the cooling speed of the coating is decreased, the generation of thermal stresses is reduced, and the coating is not easy to crack. When the gas-phase particles are sprayed onto the surface of the matrix, the gas-phase particles can be fully diffused to form a neatly-arranged columnar structure coating. In addition, the bonding force between the coating and the matrix can be better enhanced.

Description

technical field [0001] The invention belongs to the technical field of coating preparation, in particular to a method for preparing a uniform coating on the surface of a complex profile by using plasma physical vapor deposition (PS-PVD). Background technique [0002] In recent years, the rapid development of aerospace technology requires high-performance gas turbine engines to have a higher thrust-to-weight ratio. Therefore, new and higher requirements are also put forward for the blades inside the engine. The temperature at the front inlet of the turbine for an aero-engine with a thrust-to-weight ratio of 10 is 1850-1988K; The design inlet temperature before the turbine of the engine will be higher, which is expected to reach 2100-2200K. Even if the most advanced film cooling technology is adopted, the surface temperature of the turbine blade will far exceed the limit service temperature of the superalloy material used in the blade when it is in service. In addition, the...

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Problems solved by technology

However, it is difficult to achieve uniform preheating of large workpieces by the plasma flame flow of PS-PVD equipment.

The temperature at the workpiece clamping end is low, which cannot meet the spraying requirements. In the middle of the jet, the workpiece is prone to local overheating and local melting of the workpiece. In addition, it is difficult to preheat and spray multiple workpieces at the same time by using the plasma flame to preheat, resulting in low production efficiency.

There are two main reasons for this. On the one hand, the effective heating range of the flame is limited. The temperature of the PS-PVD plasma jet near the nozzle outlet is the highest, which can reach ~15550K. However, with the increase of the spraying distance, the temperature of the plasma jet decreases continuously. The temperature distribution in the radial direction of the flow is uneven, the temperature in the center of the plasma jet is high, and the temperature at the edge of the jet is low

On the other hand, although PS-PVD has the advantage of winding plating, due to the occlusion of different parts of the workpiece with complex surfaces, the plasma jet has limited heating capacity for non-line-of-sight areas.

[0008] Therefore, according to the PS-PVD process of the prior art, the uniformity of the coating at different positions is very poor due to uneven preheating when a plurality of complex profile workpieces are deposited at one time.

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