Effect of different morphological SiO2 contents on the properties of iron-based powder metallurgy materials
The research direction of SiO2 particle-enhanced powder metallurgy friction materials mainly focused on factors such as particle size,mixed particles,particle content and particle modification,with little research reported on particle morphology. In this experiment,iron-based powder metallurgical materials with spherical and irregular SiO2 particles as reinforcing medium were prepared by powder metallurgy technology,respectively,and the effects of different morphologies and different contents of SiO2 particles on the microstructures and properties of the materials were also investigated,and the microstructures,densities,hardnesses,room-temperature tensile and friction and wear properties of the materials were characterized in the tests. Spherical and irregular SiO2 parti-cles are uniformly distributed in the matrix,and no interfacial reaction occurs between SiO2/iron matrix. The den-sity of iron-based powder metallurgy materials with the addition of spherical SiO2 decreases less at the same addi-tion content. The addition of SiO2 particles significantly increases the hardness and tensile strength of the matrix.The addition of 2.0％ of spherical and irregular SiO2 increases the hardness of the matrix material from 96HBW to 161HBW and 158HBW,respectively,and the addition of 1.0％ spherical and 2.0％ irregular SiO2 increases the tensile strength of the matrix material from 161 MPa to 217 MPa and 231 MPa,respectively. The influence of the morphology of SiO2 particles on the friction and wear performance of the matrix material has the same trend,where the addition of spherical and irregular SiO2 particles significantly lowers the friction factor and wear amount of the matrix. The friction factor and wear amount of the material are significantly reduced with the increase of SiO2 particle content. Spherical SiO2 particles have good fluidity,so that the mixed powder pressing performance has been improved,conducive to material densification. The addition of hard particles can be as-sessed by the material of the applied load,play a role in strengthening the material,the introduction of spherical SiO2 in the material of the reinforcing effect is better than the irregular SiO2,the addition of SiO2 particles can make the material have more excellent mechanical properties. Under the same content,the friction and wear prop-erties of materials with spherical or irregular SiO2 particles are similar. The addition of SiO2 particles in the matrix can effectively support the friction surface,so that the material obtains a relatively flat friction film and improves the friction and wear properties of the material.
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