Preparation And Microstructure And Properties Of Ti Activated SiC Particle Reinforced High Chromium Cast Iron Matrix Wear Resistant Composites

Ceramic particulate reinforced metal matrix composites are used more and more in the field of wear resistance because of its practical and reliable technology and excellent wear resistance.The service life of metal-ceramic composite wear-resistant parts is obviously improved compared with traditional metal materials,and the economic benefits are prominent.However,due to the poor wettability between ceramic particles and metals,the stability and reliability of material preparation are challenged severely.At present,the research on iron-based metal-ceramic composites is still in its infancy in China.It is of great practical significance to strengthen the research on these materials.As a common wear-resistant material,SiC ceramics are ideal reinforcing materials because of its high hardness,high specific strength and high specific modulus.High chromium cast iron is a traditional wear-resistant material,its internal carbide can be a good reinforcing material,and its fluidity in melting state is good,suitable for casting and other processes.Inert gas protected pressureless infiltration method can provide the non-oxidizing environment needed in the preparation process,with low cost and relatively simple equipment.It is suitable for the preparation of large components.In this paper,the preparation of SiC ceramic particle reinforced high chromium cast iron matrix composites by pressureless infiltration method,the influence of active elements on infiltration process,and the structure and wear resistance of the composites were studied,which provided theoretical guidance and experimental reference for the application of such composites.Firstly,ceramic preforms were prepared by mixing the reinforced particles and the necessary active element particles under appropriate bilateral axial pressure.Mixed granular ceramic preforms and corresponding high chromium cast iron were placed in a high temperature tube furnace protected by argon,and composites were prepared by pressureless infiltration.SEM,EDS and XRD were used to analyze the internal structure,phase structure,interfacial bonding and defects of the composites.The friction and wear properties,including friction coefficient and wear rate,were tested by reciprocating friction experiment,and the wear interface was analyzed.The following conclusions are drawn:(1)The SiC/high chromium cast iron composites were successfully prepared by using Ti particles as activator,and the infiltration depth increased with the increase of Ti content.The infiltration depth of preforms containing 10% Ti is about 30% higher than that of preforms containing 5% Ti.SiC preforms with Ni and Co as active elements can not be impregnated by high chromium cast iron.Ti forms TiC by combining with diffused C elements.TiC-guided infiltration of metal liquid into preform is the key to promote infiltration behavior.(2)SiC particles are evenly distributed in the matrix of high chromium cast iron,forming a uniform composite material with good interface bonding.TiC form close interfaces with SiC particles and metal matrix;TiC,TiO,FeO and other new phases are detected.(3)The diffusion of Si element is weak,C element distributes uniformly in prefabricated body,and Cr element mainly distributes in metal matrix but diffuses to SiC particles also obviously.(4)Compared with high chromium cast iron,the composites have excellent wear reduction properties.The friction coefficient of composites decreases by more than 50% with higher chromium cast iron.The wear rate is about 1/6 of that of high chromium cast iron,and the wear process is relatively stable.Under the same conditions,high chromium cast iron enters the accelerated wear stage obviously,while the composite still exhibits excellent wear resistance.(5)According to the micro-morphology of wear surface,the wear resistance of composites is better than that of high chromium cast iron under the same conditions,and there is no obvious fatigue wear.In the course of friction,the metal matrix of the composites breaks preferentially,and the interface between metal and ceramic particles dissociates in the course of continuous friction.The reinforced particles break up without the protection of the metal matrix.The two particles gradually form hard debris and form three-body wear between the friction pairs.