高速高温条件下刷式封严环涂层与刷丝摩擦副磨损行为

Wear Behavior of Brush Seal Ring Coating and Bristles Friction Pair under High Speed and High Temperature

目的研究高速高温刮削条件下NiCr-Cr_(2)C_(3)涂层和SG37合金刷丝组成的摩擦副的磨损行为。方法利用自制的高速高温刮擦试验机,在不同进给速度和过盈量条件下进行封严环涂层与刷丝摩擦副的高速高温刮削试验。用轮廓测量仪测量刷式封严环表面涂层的磨痕深度。用超景深显微镜(OM)和扫描电镜(SEM)观察涂层及刷丝样品的原始形貌和磨痕形貌,并利用配备的EDS能谱仪分析磨痕表面元素成分,同时分析了摩擦过程中的磨损机理。结果NiCr-Cr_(2)C_(3)涂层与SG37A合金刷丝在高速高温刮擦过程中发生了磨粒磨损、黏着磨损和刷丝材料向涂层的转移。刷丝之间也存在摩擦变形和磨损,这主要是由于刷丝与刷丝在磨损过程中发生了高温变形和挤压,由于“拖尾”现象的存在,使刷丝尖端的变形和挤压更加明显,高温下金属流动性的增加进一步促进了菱形的形成。通过分析不同过盈量和进给速度对磨痕深度的影响,发现过盈量和进给速度均对涂层磨痕深度存在影响,随过盈量和进给速度的增加,涂层磨痕深度增大。结论高速高温的苛刻工况下,刷丝在磨损过程中具有显著的变形,并且过盈量对封严环涂层和刷丝样品磨损的影响更大。

Aiming at the wear problem of brush seal ring coating and bristles in aeroengine during service,the tribological behaviors of seal friction pairs composed of commonly used NiCr-Cr_(2)C_(3)seal coatings and SG37A bristles were studied under high-speed rubbing condition.The high speed and high temperature rubbing test of seal ring coating and bristles friction pair was carried out under different feed rates and interference conditions by using a self-developed high-speed rubbing tester.SG37A bristles with a diameter of 0.08 mm was used for brush seal.2 hundred bristles was placed in a 1.2 mm×1.2 mm groove,with an angle of 45°with the horizontal,and the exposed height of bristles was 2 mm.The base material of the brush seal ring simulating samples is GH4169 alloy,and the sealing coating on the surface is a double-layer structure.The bottom layer is made of CoNiCrAlY,with a thickness of 0.1 mm,which is prepared by explosive spraying;the surface layer is NiCr-Cr_(2)C_(3)containing BaF2and CaF2,with a thickness of 0.25 mm,which is prepared by plasma spraying.The tests were conducted on the self-developed high-speed friction and wear tester.The bristles and coating samples were respectively installed on the high-speed rotary table and the fixture of the feeding system.The feed speed(the radial feed rate of the coating moving to brisltles)was set to be 0.01 mm/s,0.05 mm/s,and 0.1 mm/s,the interference is 0.3 mm,0.5 mm and 1.0 mm.The linear speed of the bristles tip is 220 m/s,and the test heating temperature is 600℃.The depth of abrasion marks on the surface coating of brush seal ring was measured by contour measuring instrument.The original morphology and wear morphology of the coating and bristles friction pair were observed by Ultra depth of field optical microscope(OM)and scanning electron microscope(SEM),and the element composition on the wear surface was analyzed by EDS spectrometer,and the wear mechanism during the friction process was also analyzed.The results showed that abrasive wear,adhesive wear and transfer of bristles material to the seal coatings occur during high-speed and high-temperature rubbing between the NiCr-Cr_(2)C_(3)coating and SG37A bristles.The bristles not only rub with the coating,but also have friction deformation and wear between the bristles.This is mainly due to the high-temperature deformation and extrusion of bristles during the wear process.Due to the existence of"tailing"phenomenon,the deformation and extrusion of bristle tips is more obvious.The increase of metal fluidity at high temperature further promotes the formation of diamond.By analyzing the influence of different interference amount and feed rate on the wear mark depth,it is found that both of them have an influence on the wear mark depth.With the increase of interference amount and feed rate,the coating wear mark depth increases.Under the severe working condition of high speed and high temperature,the bristles have significant deformation in the process of wear,and the interference amount has a greater influence on the wear of the seal ring coating and bristles sample.