Microstrure And Behavior Of Self-lubricating Composite Coating Prepared By Laser Cladding

The aircraft engine is the heart of aircraft, its work related to aircraft flight safety andreliable stability. Aircraft engine main shaft seal ring is easy to wear, which affects thesafety of aircraft. The laser cladding technique is a new surface modification technology,which formed the high-performance cladding layer on the material’s surface with laserheat source. Therefore, this article proposed the introduction of "hard lubricant layer"technology ideas, using laser surface modification technology to solve the Aircraft enginemetal ring seal surface wear caused by the problem of declining performance.In this research it is introduced a5kW Laser with CO₂flow transvers for claddingCo-basealloy coat on the sealing surface. The nature of the research is to change qualitiesof friction properties with laser cladding alloy powder preplaced.Morphology and phasecomposition of the coating were attentively studied by means of metallographicmicroscopy, scanning electron microscopy（SEM） and X-ray diffraction（XRD）. Bymeasuring the material’s hardness, friction coefficient and friction curve to characterizethe cladding performance. The main research work of this paper was illustrated as follows:（1） Different power incorporated with self-melting powder by laser cladding underdifferent laser processing conditions. Cladding layer with the substrate become ametallurgical bond. The optimized parameters of cladding surface are that the laser poweris about1.5KW, scanning speed is2mm/s. The cladding of microstructure include crystalplane and dendrites. The MoS₂, WC and TiC was founded in the layer by means ofmetallographic microscopy, scanning electron microscopy and X-ray diffraction. Materialsurface hardness increased and the highest hardness is851.12HV.（2） The optimized parameters In the optimal laser processing parameters, studying ofdifferent power affect friction and wear performance of cladding layer. With the incrementof the MoS₂content, the hardness decrease, the friction coefficient decreas and lossquantity first increased and then decreased. In this test, when the MoS₂content is13.01%（mass）, the comprehensive tribology performance is optimum. With the increment of theWC content, the hardness increase, the friction coefficient and loss quantity decrease.Addition of Nano-onions should decrease layer hardness and friction coefficient. Ni-coated Nano-onions should increase layer hardness, the friction coefficient and lossquantity decrease.（3） By ball milling change the way of power mixing which affects the friction andwear properties of the cladding layer. When MoS2milling240min, the friction coefficientdecreased by32.14%and loss quantity decreased by61.85%.When the MoS2content is16.69%（mass）, the friction coefficient decreased by32.79%and loss quantity decreasedby75.92%.When the nanodiamond content is2.91%（mass）, the friction coefficientdecreased by37.85%and loss quantity decreased by80.54%.When2.91%（mass）Graphite by milling3hours, the friction coefficient decreased by26.35%and loss quantitydecreased by79.77%. When2.91%（mass） Graphite with self-melting powder by milling3h, the friction coefficient decreased by28.61%and loss quantity decreased by76.11%.