Study Of Reactive Interfical Transition Zone Construction And Properties Of ZTA_p/High Chromium Cast Iron Composites With Architecture Of Honeycomb

Ceramic particles reinforced iron matrix composites were mainly used as high efficiency wear-resistant materials in different industrial sectors such as metallurgy,mining,cement,electric power,machinery and coal.Among various ceramics,ZTA?ZrO₂ toughened Al₂O₃?is a promising reinforcement for composites due to its properties such as low price,high toughness,excellent high temperature wear resistance and better thermal matching property with iron.So far,extensive attention has been recived in the development of high-performance and low-cost ZTA particle?ZTA_P?reinforced iron matrix composites.However,it is difficult to fabricate the ZTA_P/iron matrix composites by pressureless casting owing to the poor wetting between ZTA_P and iron.In addition,the interface bonding between ZTA_P and iron is usually mechanically combined and the bonding strength is low,which results in poor reliability and poor wear-resistant of the composites in the wear service process that limits the application development space of the material.In order to solve the above problems,the surface of the ZTA particles in the honeycomb preform was covered with active ceramic powder that reacts with ZTA particles and molten iron.A reactive interface transition zone is formed in the process of pressureless casting,which promotes the molten iron infiltrating into the preform.Then the microstructure and properties of the reactive interface transition zone were studied in depth.Finally,the process stability and wear resistance of composites with reactive interfacial transition zone and honeycomb configuration were explored by means of the compression,impact toughness and abrasive wear performance tests.According to the above research,the design principle and formation mechanism of the composite reactive interface transition zone are clarified,furthermore the impregnation mechanism of the reactive infiltration process is revealed.It is demonstrated that the existence of reactive interface transition zone could optimize the composite interface and improve its wear resistance.Thermodynamic method was used to calculate the chemical reactions occurring among metal matrix,particle and powder.Four kinds of active ceramic powder such as Al₂O₃,B₄C,SiC and TiO₂ were selected.It is shown that the composites prepared by covering the above powder on the surface of ZTA particles have the reactive interfacial transition zone based on the actual results.XRD,SEM,EPMA,TEM,HRTEM and Nanoindentation were used to characterize and test the microstructure and properties of reactive interface transition zone of ZTAp/high chromium cast iron matrix composites.The results show that the amorphous structure formed by the binder at high temperature is the matrix of the interface transition zone,where the intermetallic compounds formed by the interaction of various elements in ceramic powder,high chromium cast iron and ZTA particles.Among the four kinds of powder,the composite prepared by covering ZTA particle with Al₂O₃ powder has the best compression performance.The main phases in the interfacial transition zone are3Al₂O₃·2SiO₂,FeAl₂O₄ spinel,amorphous Na₄SiO₄ and Nano-SiO₂.The hardness value is 7.1 GPa and the elastic modulus is 202.7 GPa.The properties of the interfacial transition zone are between the ceramic particles and iron matrix,which can effectively transfer the loads.The mechanism of reactive infiltration was studied from the perspective of thermodynamics and kinetics.When the molten high chromium cast iron infiltrate the preform,the binder first reacts to form amorphous structure,and then Fe,Cr,Mn and other elements in high chromium cast iron diffuse into the amorphous structure at high temperature.These diffused alloying elements react with active ceramic powder and form intermetallic compounds as a result of increase of the concentration difference of alloying elements in the interfacial transition zone,thus promoting the further diffusion of metal elements of high chromium cast iron and ultimately increasing the infiltration depth.The compression,impact toughness and abrasive wear properties of ZTAp/high chromium cast iron matrix composites with reactive interfacial transition zone and honeycomb configuration were tested.The results show that the reactive interfacial transition zone can improve the effect of"Micro-shadow effect"of ceramic particles effectively and avoid the peeling of particles under external forces.The honeycomb structure can provide"Macro-shadow effect"to protect the matrix effectively,thus improving the mechanical properties and wear properties of the composites significantly.In this paper,by constructing reactive interface transition zone and studying reactive infiltration mechanism,new ideas and methods are provided to solve the infiltration problem of non-infiltrating ZTAP/high chromium cast iron matrix composites and improve their interface bonding,which enriches the in filtration theory of composites and lays an experimental and theoretical foundation for the industrial application of ceramic particles reinforced iron matrix wear resistant composites.