The Study On The Microstucture And The Friction Behavior Of 3D-Meshy SiC/20Cr Composite Material

With the improvement of the traffic, transport machinery speed and carrying capacity, excellent property of friction material is needed. Recently, a new type of composite material has attracted widespread interest—interpenetrating phase composites.3D-Meshy SiC/metal composite materials are made of SiC and metal, which support each other as skeleton. The composite materials don't only possesse properties of SiC ceramics such as low density,high hardness, good wear resistance and high-temperature stability, but also high sthrenth and ductility of metal. The interface between Skeleton and matrix has strongly affected physical and mechanical properties. Therefore, the study on the interfacial reaction between SiC skeletons and 20Cr matrix has important theoretical and practical value.In this paper, the microstructure and formation mechanism of SiC/20Cr composite materials interface has been studied, and friction characteristics of SiC/20Cr used as break couple and the changes of interface microstructure were investigated.The results showed that:(1)There was good interfacial adhesion between 3D-Meshy SiC and metal. The reaction zone included three zones, SRZ, MRZ and C-PFZ. SRZ near SiC was mainly composed of graphite and Fe3Si matrix, C-PFZ near alloy a-Fe(Si), MRZ between SRZ and C-PFZ was Fe(Si) matrix, (Cr,Fe)7C3 compound, Cr7C3, spheroidal and flaky graphite and Fe3C.(2)In the reaction zone of SiC/20Cr alloy interface, the reaction between C, Si atoms decomposed by SiC and metal atoms had selectivity. Because of strong C-Cr affinity, C atoms was always priority to diffuse to the rich Cr alloy zone, reacted with Cr and formed M7C3 compound. Meanwhile, most of Si atoms reacted with Fe atoms to form Fe3Si. The diffusion rate of C atoms was bigger than Si atoms.(3)The solid state reaction between 3D-Meshy SiC/20Cr interface was under the control of Fe diffusion. Graphite, Fe3Si and carbide-derived Cr prevent effectively Fe diffusion. Reaction taking place in the liquid was the main reaction. The products made the solid state reaction difficult. Solid-phase diffusion played a great role on uniform and ordering of interface products.(4)Inertial force Rig test showed that:the composite material had excellet properties such as smooth torque curve, stable friction coefficient, good wear resistance and Thermal shock resistance. (5)After RTO, the interface of SiC/20Cr changed greatly. The content of Fe3Si increases, M7C3 carbides changed into M23C6 carbides, only little M7C3 carbides exsited. The elements distributed uniformly in the interface. SRZ is larger, and there were lots of flaky graphite and Fish-bone (Cr,Fe)23C6 eutectic carbides in SRZ. The boardline of C-PFZ and MRZ became apparent, but the one of C-PFZ and 20Cr was fuzzy.