Study On Preparation Of High Toughness Wear-resisting Silicon Nitride Ceramic Material Based On Multiphase Reinforced Phase

In the harsh metallurgical production environment such as high speed wire mill production line,silicon nitride ceramic materials with excellent properties such as high temperature resistance and wear resistance have become the preferred materials for various wear resistant parts.It is found that the inherent brittle fracture of silicon nitride ceramic material seriously affects its service life in production.This topic aims at the practical application requirements of silicon nitride ceramics as wear-resistant materials in the field of metallurgy.By adding one or more combination of reinforcement phases to ceramic materials to toughen the way,regulate the microstructure,improve the mechanical properties of silicon nitride ceramic materials,especially the fracture toughness and friction and wear properties,to meet the needs of the actual production process.The main research work is as follows:C_f/Si₃N₄silicon nitride ceramic materials were prepared by using carbon fiber powder as reinforcement phase.When the content of carbon fiber was0.5%,the C_f/Si₃N₄silicon nitride ceramic material with the best comprehensive performance was prepared,with the resulting density reaching about 92%and the bending strength reaching（587.57±35.11）MPa,which was 21.22%higher than that of the control group（484.74±21.15）MPa.Hardness decreased to（13.16±0.37）MPa;The fracture toughness reached（9.77±0.51）MPa·m^1/2.The optimum amount of carbon fiber in silicon nitride ceramic material is about0.5%～1.5%（mass fraction）.W Si₃N₄silicon nitride ceramic materials were prepared with tungsten as reinforcement phase.When the tungsten content is 5%,the composite properties of W/Si₃N₄silicon nitride ceramic materials are the best,with the relative density reaching 97%,fracture toughness reaching（9.25±0.14）MPa·m^1/2,Vickers hardness reaching（16.42±0.22）GPa and bending strength reaching（670.28±40）MPa.It is determined that the optimum addition amount of tungsten in silicon nitride ceramic material is about 5%（mass fraction）.The composite silicon nitride ceramic materials were prepared by adding tungsten and carbon fiber as reinforcement phases in a certain gradient.When carbon fiber content is 0.5%and tungsten content is 6%,the relative density of the composite silicon nitride ceramics is 98%.The C1W6S-Si₃N₄silicon nitride ceramic material with the best comprehensive performance was obtained,with the bending strength reaching（736.78±29.8）Mpa,hardness reaching（16.19±0.47）GPa and fracture toughness reaching（11.06±0.37）MPa·m^1/2,which increased by 25.40%compared with tungsten alone.Dry sliding reciprocating friction tests were carried out on SW0-Si₃N₄,SC1-Si₃N₄,SW5-Si₃N₄and C1W6S-Si₃N₄ceramic materials,and the friction and wear properties of four kinds of silicon nitride ceramic materials and commercial ceramic ball pairs were analyzed.It was found that the average friction coefficients of four kinds of ceramic materials increased with the increase of load（20N,40N,60N）.The average friction coefficients of SW5-Si₃N₄and C1W6S-Si₃N₄ceramic materials are better than those of SW0-Si₃N₄ceramic materials under three kinds of loads.At different sliding frequencies（2Hz,3Hz and 4Hz）,the average friction coefficient of SW5-Si₃N₄ceramic materials first increases and then decreases with the increase of sliding frequency,and the maximum and minimum friction coefficients are 0.507（3Hz）and 0.413（4Hz）,respectively.The average friction coefficient of C1W6S-Si₃N₄ceramic materials decreases continuously with the increase of sliding frequency,and the lowest friction coefficient is 0.450（4Hz）.It can be seen from the above that C1W6S-Si₃N₄ceramic material has the best comprehensive properties and can be used as the preferred material for wear-resistant parts in the field of metallurgy.This paper not only provides a reference method for improving the toughness of silicon nitride ceramics,but also provides help for promoting the wide application of ceramic materials in high-end metallurgical equipment and improving the production efficiency of rolling steel.