| As one of the most core functional parts of rotating machinery,bearing plays a decisive role in the performance,reliability and service life of the whole system.When the sliding bearing is working,the bearing bush is in direct contact with the journal,which is easy to produce greater wear and affect the normal operation of the mechanical system.Therefore,the research on the wear resistance and lubrication properties of the bearing bush materials has been widely concerned.At present,the research on reinforced composite coating is mostly ceramic reinforced composite coating,but the research on cermet reinforced composite coating is less,and the research on the composite coating with cermet as reinforcement phase and soft metal as lubrication phase is even rarer,and the existing cermet reinforced composite coating has the problem of low bonding strength with the substrate.Therefore,in this paper,based on cold spraying technology and material strengthening principle,the design and preparation of tin bronze matrix composite coating with good mechanical and tribological properties,mechanical properties and tribological properties of the coating were studied.The main research results are as follows:Firstly,based on the principle of deformation strengthening and dispersion strengthening of coatings by WC-17 Co hard ceramic particles in the process of cold spraying,Cu Sn10/WC-17 Co composite coatings with different contents of WC-17 Co were designed and prepared on the surface of 304 stainless steel matrix.The results show that the deposition efficiency of the coating decreases with the increase of the content of WC-17 Co.In addition,the surface roughness of the coating decreases with the increase of tungsten carbide content,and the internal structure of the coating becomes denser with the increase of tungsten carbide content.No decarburization or phase transition occurs during the coating spraying process.The hardness and bonding strength of the coating increase with the increase of tungsten carbide content,and the highest values are 331 HV0.3 and 60 MPa,respectively.The results of rotating friction test at room temperature show that the wear rate of coating decreases from9.1×10-4 mm3/N·m to 1.3×10-5 mm3/N·m with the increase of tungsten carbide content.The mechanism of coating wear changes from the oxidation adhesion wear of tin bronze coating to the slight abrasive wear of composite coating.Then,based on the dispersion strengthening effect of WC-17 Co cermet particles and the lubrication effect of soft metal Ag,the low-pressure cold-sprayed Cu Sn10/WC-17Co/Ag composite coating was prepared.No oxidation or phase transformation occurred in the deposition process of the coating,and the internal structure of the coating is uniform and compact.The coating maintains good bonding strength.The reciprocating friction tests with different friction rates and loads were carried out in the atmosphere at room temperature.The friction coefficient of Cu Sn10/WC-17Co/Ag composite coating was much lower than that of in Cu Sn10/WC-17 Co composite coating at different friction rates under a load of 30 N,and the friction coefficient reached the lowest value of 0.42 at the friction rate of 0.1 m/s;At a fixed friction rate of 0.06 m/s,the friction coefficient of Cu Sn10/WC-17Co/Ag composite coating is smaller than that of Cu Sn10/WC-17 Co composite coating when the load is greater than 20 N,and the minimum value is 0.43 when the load is 50 N.The Cu Sn10/WC-17Co/Ag composite coating exhibits excellent wear resistance under different friction rates and different loads,and its wear rate reaches the order of 10-6 mm3/N·m,which is much lower than that of Cu Sn10/WC-17 Co composite coating.The main wear mechanism of Cu Sn10/WC-17Co/Ag composite coating is oxidation wear and abrasive wear. |
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