Study On Preparation Of WC/CU Composite By Freezing Casting- Pressureless Infiltration Method

Nacre-inspired lamellar composites has excellent properties such as high strength and high toughness.The freeze casting-pressureless infiltration method is one of the methods for preparing the nacre-inspired lamellar composites.The method can flexibly control the structure and size of the composite and obtain meticulous lamellar structure.At present,the research on the preparation of nacre-inspired lamellar metal matrix composites by freeze casting-pressureless infiltration method mainly focuses on aluminum matrix composite.Researchers domestic and foreign have used this method to prepare Al₂O₃/Al-12Si,SiC/2024Al and Al₂O₃-ZrO₂/Al-Si-Mg nacre-inspired lamellar composites with meticulous structure and fine mechanical properties,but lack of research on copper matrix composite.Copper is a good conductive and thermal material,but its strength,hardness and wear resistance are poor.WC particles have better electrical conductivity,thermal conductivity and high strength and hardness than other ceramic materials,and have good moisture with copper,so WC particles are considered as the preferred reinforcement for copper.WC/Cu composites have higher strength,hardness,wear resistance and thermal stability than pure Cu,and have broad application prospects in various fields.On this study,copper using as the matrix material and WC as the rei nforcement,the WC/Cu composites with nacre-inspired lamellar structure have been prepared by freeze casting-pressureless infiltration method.Then,we analyzed the microstructure and properties of WC/Cu composites prepared by different process parameters.The main findings of this paper are as follows:（1）WC/Cu composites with intact structure and no pore defects were prepared by freeze casting method and pressureless infiltration method,and the volume fraction of WC was 15%-25%.When the composite material changes along the bottom to the top of the preform,the thickness of the metal layer gradually increases from 5μm to 57μm,and is linearly distributed with the distance of the cold source;（2）WC content is the main influencing factor affecting the microstructure and properties of composites.By analyzing the microstructure,mechanical properties and thermal conductivity of composites with different WC content,it is found that when the WC content increases from 15vol.%to 25vol.%,The thickness of the top metal layer of the composite material decreased from 120μm to 16μm,the macro hardness increased from 112HV to 155HV,and the compressive strength increased from383.92MPa to 642.52MPa.The thermal diffusivity change trend was abnormal,and the content was 15vol.%WC.82.916 mm²/s first decreased to 69.893 mm²/s at 20 vol.%WC and increased to 72.540 mm²/s at 25 vol.%;（3）The amount of glycerin added has a great influence on the microstructure of the composite.The size and thickness of the metal sheet decrease with the increase of glycerin addition,but the glycerol content has little effect on the macro-hardness and compressive strength of the composite;The freezing temperature has a great influence on the microstructure and mechanical properties of W C/Cu composites.The higher the freezing temperature,the greater the thickness of the metal layer of the composite,the worse the permeability of the layered structure,the smaller the macro-hardness and compressive strength.