| Titanium silicon carbide (Ti3SiC2) is a new class of ceramic material, which possessesthe advantages of both metal and ceramic. Ti3SiC2has many unique properties, such asself-lubricating property, excellent electrical and thermal conductivity, good machinability,excellent thermal shock and high-temperature oxidation resistance, etc. Ti3SiC2has a broadapplication potential as high temperature structural materials, electrode materials andorthopedic biomaterials due to these unique properties. In this work, double-layer crucibleswere used to reduce the loss of reactants, and we fabricated high purity Ti3SiC2by presslessreactive sintering successfully with different molar ratio of Ti/Si/C. Cu-Ti3SiC2compositeswere prepared by adding Ti3SiC2powder of5wt.%,10wt.%,15wt.%,20wt.%,25wt.%intothe copper matrix by SPS at700℃and950℃. And we also studied the mechanical andfriction and wear performance of the composites. Because there are some disadvages bytraditional methods to fabricate the composites, so we consider to use melt infiltration toprepare Cu-Ti3SiC2composites. The first step of melt infiltration is to prepare porousframework. Porous Ti3SiC2was made by adding pore former (NaCl、 NH4HCO3andC18H36O2).Ti3SiC2bulks were obtained by using Ti, Si, C powders as raw materials. Results showthat double-layer crucibles do have an effect on the purity of Ti3SiC2. High purity Ti3SiC2bulks were obtained by sintering at1500℃for120minutes with original molar ratio of3Ti/1.05Si/2C. Pure Ti3SiC2could also get with a ratio of3Ti:1.2Si:1.8C washed by HF acid.Compared to other ceremics, the expansion coefficient and elastic modulus of Ti3SiC2are closer to those of copper, which can help to reduce the thermal stress between Cu andTi3SiC2, therefore, Ti3SiC2is a promising filler material for Cu-matrix composite. Cu-Ti3SiC2composite were prepared by adding Ti3SiC2powder of5wt.%、10wt.%、15wt.%、20wt.%、25wt.%into the copper matrix by SPS sintering method. Cu-Ti3SiC2can be synthesized at700℃,while, a small amount of impurity phases of TiC and TiSi2could be found at950℃.The relative density, hardness and bend strength of Cu-Ti3SiC2sintered at700℃were lowerthan samples sintered at950℃. With the content of Ti3SiC2increase, the density and bendstrength of the composites decrease, while the hardness and resistivity increase.We studied the friction and wear performance of Cu-Ti3SiC2composites under differentconditions, including dry, charged and heated frction. The results show that the purity of thecomposites has an effect on the property. The more pure the composites are, the lower friction coefficient and wear volume it has. So it is better to use pure Cu-Ti3SiC2when the purpose isto get friction coefficient reduced.Spark Plasma Sintering (SPS), Hot Pressing Sintering (HP) and pressureless sinteringwere studied to fabricate Cu-Ti3SiC2composites. Better comprehensive performances ofCu-Ti3SiC2composites were got by SPS sintering, but Ti3SiC2appeared to get agglomeration.Lower density which got by pressureless sintering had a negative effect on the performance ofthe composites. Hot pressing Sintering (HP) was not easy to promote, because the equipmentwas expensive and sintering size was limited. So we considered to use the melt infiltrationmethod to get Cu-Ti3SiC2composites with good properties, while the first step was to get aporous framework. High purity porous Ti3SiC2with controlled pore structure and porositywere prepared by using elemental powders with different pore formers. By using differentkinds of pore formers, we all got porous materials with high porosity and open porosity. Itturns out that with adding more and the bigger the particle size of pore former, the porosityand open porosity also increased. The pore morphology of porous materials which was madeby using NaCl or C18H36O2was better than that of which added NH4HCO3. |
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