Research On Preparation And Microstructure Of ZTA Ceramic/High Chromium Cast Iron Matrix Composites

Most of the mills used in power plants are made of traditional high chromium cast iron wear resistant materials,which greatly restrict the quality and performance of the coal mill,can not meet the requirements of wear resistance.Ceramic particle reinforced metal matrix wear resistant composite material has become the preferred material to replace traditional steel wear resistant materials.The wear-resistant parts such as grinding roll,grinding disc and so on are composed of ceramic / high chromium cast iron metal matrix composite.The service life is 2.5³ times of ordinary high chromium alloy or surfacing alloy.At present,the wear resistant composite material preparation is still limited in laboratory research,ceramic / metal matrix composites of high chromium cast iron grinding roller are imported,so the significance of application of ceramic particle reinforced steel matrix composite material.In this study,zirconia toughened alumina ceramic?ZTA?particles and high chromium cast iron were used as raw materials to prepare the composite.The molding pressure,sintering temperature,holding time and the effect of adding Ti particles on the strength and porosity of ZTA ceramic preform were studied.ZTA ceramic / high chromium cast iron composite has been prepared by Pressureless infiltration.The structural characteristics and distribution of chemical elements in ZTA ceramic / high chromium cast iron composite were observed and determined by SEM,EDS and XRD.The infiltration mechanism of ceramic / high chromium cast iron composite and the bonding mechanism between metal phase and ceramic phase were analyzed.The result showed as follows:?1?The molding pressure,sintering temperature and holding time have an important influence on the performance of molding.By experiment,the preform is well formed when the forming pressure is 30 MPa,the sintering temperature is1300?,and the holding time is 60 min.With certain strength,porosity and ZTA ceramics with different amount of Ti prefabricated body prepared by this process,with the increase of Ti content,the preform porosity increases and the strength decreases gradually,and there is a small amount of TiO₂.?2?In contrast to the contact angle of high chromium cast iron on Ti containing and Ti free ceramic substrates,the addition of Ti to ZTA ceramic particles can improve wettability between high chromium cast iron and ceramics.The composite material was prepared by pressureless infiltration process with slow cooling of furnace after soaking temperature of 1500? and soaking holding time of 60 min.In addition,the amount of Ti in the preform increases,and the infiltration effect increases.?3?Metal infiltration with Ti content of 20% of the preform formed in thecomposite,the metal and ceramics are evenly distributed and bonded tightly.The compositions of the composites mainly include Al2O3,ZrO₂,Fe-Cr-C,FeAl2O4,Fe TiO5,AlCrO3 and FeTi.The interface between metal and ceramic has the mutual diffusion and chemical reaction of elements in the composite.The main interface and metal ceramic composite materials with phase with metallurgical bonding,mechanical binding,binding reaction consisting of binding mechanism,binding mechanism of this is conducive to the composite metal phase and ceramic phase better play their respective roles.