Study On Erosion Resistance Of SiC Foam Ceramic/ductile Iron Co-continuous Phase Composites

Erosion wear refers to the phenomenon that a large number of tiny particles in the fluid medium impact the surface of the material,causing surface fatigue,fracture,spalling,etc.,and is one of the main forms of workpiece failure of a grinding roller and grinding disc of the grinding machine used in a large number of industries such as thermal power,cement,and mining,resulting in a large consumption of energy and wear-resistant steel.Therefore,the development of high-performance wear-resistant steel is an effective means to reduce wear and improve the service life of the workpiece,and is also an urgent need for high-performance wear-resistant materials in the above industries.SiC foam ceramics were prepared by polymer pyrolysis combined with reaction sintering.The molten ductile iron was injected into the mesh of SiC foam ceramics by extrusion casting process to prepare SiC foam ceramic/ductile iron co-continuous composite(SiCfoan/DI).In the composite,a three-dimensional communication network between the ceramic phase and the metal phase in the three-dimensional co-continuous composite of SiC foam ceramic/ductile iron formed two mutually interconnected and mutually supported three-dimensional communication networks.This interpenetrating network structure helped to maximize the retention and utilization of the two phases,and was expected to greatly improve the erosion resistance of composite.In order to verify this expectation,this paper developed a gas-solid two-phase flow erosion test to systematically investigated the impact of erosion time(t),particle impact velocity(v),erosion angle(a),volume fraction of SiC foam ceramics,SiC foam ceramic pore diameters,SiC particle size and other factors on the erosion performance of SiC foam ceramic/ductile iron co-continuous composites,SiC particle reinforced ductile iron composites(SiCp/DI)and simple ductile iron(DI),the eroded surfaces of these materials were analyzed by scanning eletron microscope and 3D laser confocal microscope,the erosion mechanisms of these materials were preliminarily determined.The erosion performance provided basic data and theoretical basis for further application of co-continuous wear-resistant composites.The main findings were as follows:(1)Under the same erosion conditions(?=75m/s,?=300),the erosion rates of SiCfoam/DI,SiCp/DI and DI are generally decreased and tended to be dynamically stable with the erosion time,but the specific change law had obvious differences:the erosion rate of DI increased with the erosion time firstly increased and then decreased;the erosion rate of SiCfoam/DI and SiCp/DI increased with the erosion time,they droped to dynamic stability,but in the dynamically stable stage,SiCfoam/DI exhibited a distinct zigzag variation.After the erosion rate reached dynamic stability,the erosion rate of DI was roughly 1.7-2 times that of SiCp/DI and 3.2 times that of SiCfoam/DI.SiCfoam/DI showed the best erosion resistance.(2)Under the same erosion conditions(?=30°,t=200min),the erosion rates of SiCfoam/DI,SiCp/DI showed different characteristics and with increase of erosion angle a:the erosion rate of DI increased with the increase of the erosion angle a,and it firstly increased rapidly and then slowly growed to remain basically unchanged;SiCp/DI,firstly increased,then decreased,and then increased.The maximum erosion rate reached the maximun at around 45°;at 450°impact angle,the erosion rate of SiCfoar./DI also reached the maximum,and the value was 10%-20%lower than the maximum value of SiCp/DI.However,when the impact angle was less than 40?,the erosion rate of SiCfoam/DI was only about 50%of SiCp/DI,which was about 25%of DI,showing good resistance to low angle erosion.After the impact angle was greater than 45°,the erosion rate of SiCfoam/DI decreased rapidly with the increase of the erosion angle,and then remained basically unchanged.(3)Under the same erosion conditions(a=300,t=200min),for SiCfoam/DI and SiCp/DI,the volume fraction of silicon carbide ceramics was 53%,the erosion rate of SiCfoam/DI,SiCp/DI and DI all increased with the increase of the impact velocity,but the SiCfofeam/DI growth rate was significantly lower than that of SiCp/DI and DI,showing excellent high-speed erosion resistance at low impact angles.(4)The volume fraction had a great influence on the foam ceramics.Under the same erosion conditions(?=30°,?=87.5m/s,t=200min),as the volume fraction increased,the erosion rate of SiCfoam/DI decreased rapidly,when the volume fraction was greater than 60%,SiCfoam/DI had the same erosion resistance as dense reaction-sintered SiC ceramics.(5)Unique co-continuous interpenetrating structure of SiC foam ceramics and cast iron unique co-continuous interpenetrating structure providing strong constraint and shadow protection effect were the main reason for SiCfoam/DI better erosion resistance than SiCp/DI and DI.