中国航发贵州红林航空动力控制科技有限公司

"In-situ alloying"facilitates agile and swift adjustments to alloy compositions,thereby unlocking a multitude of prospects for developing novel alloys with distinctive microstructures.In this study,TC4-x316L alloys(with x=1%,3%,and 5%by mass)are fabricated through the combination of selective laser melting(SLM)and the in-situ alloying approach.The effects of varying concentrations and SLM process parameters,including scanning rate and laser power,on the microstructural characteristics and mechanical properties of the alloys are investigated using metallographic microscopy(OM),scanning electron microscopy(SEM),XRD,and tensile testing.The results indicate that an increase in 316L content refines the alloy's micro-structure,causing the martensitic α' phase to transform into the β phase.The alloy's hardness initially rises and then decreases slightly,while its strength peaks at an x value of 1%.Specifically,when the laser power is set to 175 W and the scanning rate to 1000 mm/s,the TC4-1%316L alloy exhibits a yield strength of 1200 MPa,a tensile strength of 1425 MPa,and an elongation at break of 6.8%.

The axial force balance design of the impeller of the fuel centrifugal pump is an important way to improve the product performance,life,reliability and other technical indicators.With the development of aeroengine technology,more stringent requirements are put forward for the axial force balance design of the impeller of the fuel centrifugal pump;The existing design technology,simulation technology and testing technology cannot to accurately guide the axial force balance design of the impeller,resulting in frequent failures such as abnormal wear of the fuel centrifugal pump.This paper analyzes the structural characteris-tics and working principle of the fuel oil centrifugal pump,and designs a new technology to measure the axial force of the impeller during the working process of the fuel oil centrifugal pump.This technology transfers the axial force carried by the fuel oil centrifugal pump during the working process to the piston of the actuating cylinder,and then uses the closed-loop control principle to control the hydraulic pressure in the two chambers of the actuating cylinder to ensure that the piston position of the actuating cylinder re-mains unchanged under the axial force of the impeller.The axial force of the impeller can be calculated by the hydraulic pressure of the two chambers of the actuating cylinder and the hydraulic action area.The testing technology studied in this paper solves the problem of testing the axial force of the impeller during the working process of the fuel oil centrifugal pump,can effectively guide the axial force balance design of the impeller of the fuel oil centrifugal pump and optimize the product structure,thus improving the reliabil-ity of the product.

For improving the corrosion resistance of aircraft structural components，zinc nickel alloy films were prepared on the surface of 18Cr3Ni structural steel using closed field non-equilibrium magnetron sputtering technology，and the effects of zinc and nickel target currents on the surface morphology，microstructure and corrosion resistance of the films were investigated.The microstructure，crystal structure and mechanical properties of the thin film were analyzed by scanning electron microscopy (SEM)，X-ray diffraction (XRD) and nanoindentation apparatus，respectively.In addition，the electrochemical properties and resistance to neutral salt spray corrosion of thin films were studied，and the corrosion products were analyzed.Results showed that the zinc nickel alloy thin film prepared by closed field non-equilibrium magnetron sputtering technology possessed a dense structure.Besides，the nickel in the film played a role in refining the grain size，but the increase of nickel content could decrease the corrosion resistance of the film.The film with Ni content of 7.63%(atomic fraction，the same below) exhibited the best corrosion resistance，but poor mechanical performance.By contrast，the film with Ni content of 12.88%had excellent corrosion resistance and mechanical performance.The corrosion product Zn5(OH)8Cl2·H2O produced by the neutral salt spray test on the film had a passivation effect，preventing further corrosion of the film and substrate.In general，the zinc nickel alloy thin films prepared by magnetron sputtering could be used for corrosion protection on the surface of precision structural components.

To solve the problem of stuck phenomenon for a double slide valve,the internal flow field of the slide valve and the force of key parts were analyzed by the fluid-structure interaction(FSI)simulation.The influence law of different inlet size and valve sleeve oil port structure on the flow field in the valve chamber and the radial force of the spool were summarized,and the range of overturning angle of the spring seat during the spool opening was obtained.The results show that the oil velocity and hydraulic impact can be reduced by increasing the size of the inlet port and the number of holes in the valve sleeve,as well as reducing the diameter of valve sleeve holes and the freedom of movement of the spring seat,so that the circumferential pressure distribution of spool is more uniform,and the balance of radial force of spool can be improved.Based on this,the valve structure was improved and verified through experiments.The experimental results show that after the oil inlet diameter of the double slide valve is changed to 8 mm,the number of valve sleeve holes is changed to 6,the diameter of valve sleeve holes to 4 mm,and canceling the contact form between the spool and the spring seat point,the spool is switched at least 600 times under two working conditions,and there is no scratch on the surface of the valve core.The improved dual slide valve fully meets the design requirements.