Thermo-mechanical Simulation Of SiC Ceramic And K4169 Alloy Composite Castings

There is an obvious complementary relationship between the performance of metal materials and ceramic materials.If the two can be effectively combined,a metal/ceramic that combines high temperature creep,corrosion resistance,thermal shock resistance and other excellent characteristics can be obtained Composite components.In this paper,K4169 alloy and Si C ceramics are used as the research objects.The numerical simulation technology is used to study the influence of interface form and temperature on the bending properties of composite castings.The steady state heat transfer,unsteady state heat transfer,and heat transfer temperature on upright honeycomb are studied.The influence of high temperature bending of the grid structure,inclined honeycomb structure and simple grid structure;the casting system was designed for gravity casting and centrifugal casting respectively for the three grid structures,and the filling and solidification processes of the three grid structures were studied and optimized.The casting process parameters were improved,and the shrinkage and shrinkage defects of composite castings were improved.Based on ABAQUS,a three-point bending model of composite castings was established.The simulation results show that the maximum equivalent stress of the flat interface structure is 373 MPa,the sawtooth interface is reduced by 12.1% compared to the flat interface,the wave interface is decreased by 14.2% compared to the flat interface,and the irregular interface is reduced.The stress concentration is improved,and the normal temperature bearing capacity of the structure is improved.When the interface depth is 8?14mm,under the same interface depth,the wave interface can improve the bending resistance better than the sawtooth interface;when the interface depth is greater than 14 mm,the sawtooth interface should be selected.The high-temperature bending simulation results of the composite casting show that temperature has a greater influence on the bending performance of the composite casting with sawtooth structure,and the effect is more obvious as the temperature increases.Compared with the maximum equivalent stress at 25°C,the maximum equivalent stress at 800°C increased the flat interface structure by 30.4%,the sawtooth interface structure by 34.62%,and the wave interface structure by 34.22%.The steady-state thermal-mechanical coupling analysis results of the composite castings with grid structure show that the maximum equivalent stress of the three grid structures appears at the interface connection and is biased to the ceramic side when there is no wind load;after the wind load is applied,the Si C ceramic part There is a large stress concentration at the outer beam,and the difference between the stress distribution of the alloy and the ceramic is obvious at high temperature;after the ambient temperature reaches 400 ?,the fixed end surface obviously plays a role in stress sharing.At high temperature,the grid element shares the stress concentration as a whole;The temperature-stress curves of the composite castings with grid structure all have inflection points,and the stress and thermal stress caused by the wind load partially cancel each other out.The unsteady thermal and mechanical coupling analysis results of the grid-structured composite casting show that when the Si C ceramic end surface is continuously heated and no wind is applied,the stress of the grid component is mainly concentrated on the left fixed end surface and the composite interface,and the ceramic side relieves The important role of thermal shock and thermal stress sharing.When the Si C ceramic end surface is continuously heated and wind is applied,the stress of the alloy end surface is greater than that of the ceramic end surface as the heat transfer continues,and stress concentration occurs at the Si C ceramic end surface during the initial heat transfer.As the heat transfer time increases,the ceramic end surface The stress is gradually relieved.When the casting speed of composite casting with upright grid structure is set at 0.6kg/s,0.7kg/s,0.8kg/s,0.9kg/s,1.0kg/s and 1.1kg/s,the filling time will decrease The solidification fraction of the mold stage gradually decreases,and the solidification time gradually increases,but the actual liquid velocity of the casting also increases,the impact of the molten metal on the mold is also greater,and the liquid flow is prone to turbulent flow.After the decrease,the trend is increased,so the pouring rate of the composite grid is 0.9kg/s.The suitable casting speeds of composite castings with three structures of upright honeycomb,inclined honeycomb and simple grid are 0.9kg/s,1.1kg/s and 0.7kg/s respectively.The casting simulation results of grid-structure composite castings indicate that the casting temperature of gravity and centrifugal casting methods are both 1440?,and the preheating temperature of mold and Si C ceramics are both 920?.The optimal rotational speed of the centrifugal casting mold for composite castings with grid structure is 550r/min.At this time,the filling process is even and stable,and no insufficient casting occurs.Centrifugal casting can be used to improve the pouring quality of the upright honeycomb grid structure and the oblique honeycomb grid structure,while the gravity gravity casting of the simple grid structure can get better pouring quality.