Shaoquan Liu

In this paper, a brake cylinder coating comprising a composite material of an Fe₃Al and Cr₃C₂ mixed powder was prepared by adding laser cladding onto carbon structural steel. We studied the influence of process parameters on the microstructure and tribological properties of the cladding materials using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and 3D white light interferometer and wear tests. The influence of different processes on the morphology of the carbide strengthening phase was found to be relatively small with a Cr₃C₂ content of 15 wt.%. The carbides mainly exhibited a network structure in each group of cladding layers. The area of the network strengthening phase varied under different processes. Of the cladding layers formed with different processes, the scanning speed of the 0.003 m/s cladding layer had the lowest wear rate. When the laser power was too low or the powder feed rate was too high, unmelted Cr₃C₂ particles could be found in the cladding layer. During the wear process, the particles peeled off, causing severe abrasive wear. When the powder feeding rate was too low, more materials in the base material entered the cladding layer. This made the composition of the cladding layer similar to that of the grinding material, resulting in severe adhesive wear.

In this paper, a brake cylinder coating comprising composite material of Fe₃Al and Cr₃C₂ mixed powder was prepared by laser cladding onto carbon structural steel. The microstructure of the cladding materials was investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The influence mechanism of the Cr₃C₂ content and process parameters on crack generation of Fe₃Al/Cr₃C₂ composites were studied. The crack is mainly caused by the mismatch between the plastic phase of Fe₂AlCr, the brittle phase of Fe₃Al, and Cr₇C₃ in the cladding layer. With the increase in Cr₃C₂ content, Fe₂AlCr and Cr₇C₃ in the cladding layer increased, while Fe₃Al decreased. When the content of Cr₇C₃ is low, the cladding layer mainly reflects the plastic increase brought by Fe₂AlCr; when the content of Cr₇C₃ is too much, the property of the cladding layer is reflected as the brittleness of Cr₇C₃. The number of cracks reached the lowest value at 15 wt.%. The process parameters mainly affect the dilution rate of the cladding layer and thus affect the content of Fe₂AlCr.