Study On The Properties Of WC-10Co Cemented Carbide Reinforced By Multi Walled Carbon Nanotubes

With the development and progress of modern industry and the constantly upgrading of industrial products, the requirements of materials performance of products in industry have become higher and higher. A variety of high-quality,high-performance materials are developed and widely used. But at the same time, it is become more and more difficult to processing and cutting. The performance processing tools can not meet the requirement and new type of cutting tools need to be developed. The cemented carbide knew as “industrial teeth” plays a very important role in many areas of industrial production and processing. Cemented carbide have a key role in cutlery, mold, cutting tools and wear parts, etc. But the traditional cemented carbide has a antiproperty of hardness and toughness. This property limited severely its applications.In this article, cemented carbides with excellent mechanical properties was fabricated by using multi-walled carbon nanotubes(MWCNTs)as the reinforcing phase and WC-10 Co as the matrix. The vacuum sintering was employed.The graphitization treatment under of carbon nanotubes were studied in vacuum at 2800 ?.The disperstiveness of the raw multi-walled carbon nanotubes(R-MWCNT)and graphited multi-walled carbon nanotubes(G-MWCNT)was also researched in ethanol. The dispersion of carbon nanotubes was explored when adding different proportions of dispersant of TNADIS in the solvent. The ultrasonic vibration and high speed shearing process were used in the dispersion process. The effect of the dispersant and graphitization were investigated to the disperstiveness of MWCNTs.The reaction of MWCNTs mixed with metal W powder under the vacuum1400 ? was researched. By analyzing XRD patterns and SEM and TEM images of the mixture before and after reaction, the reaction mechanism of MWCNTs and metal W powder in this condition was studied.MWCNTs were added to the cemented carbide powder by physical mixing. The vacuum sintering process was employed to fabricated the cemented carbide product.The dispersion of carbon nanotubes in cemented carbide and the carbideperformance were also researched with different content of MWCNTs.The results showed:The purity of the carbon nanotubes was substantially increased by high temperature heat treatment. The carbon atoms were arranged in crystalline and the defects of carbon nanotubes were reduced.The crystalline structure of carbon nanotubes was also improved. The crystallinity of carbon nanotubes of 89.6% was obtained. The dispersion effect of G-MWCNTs was not as good as R-MWCNTs.MWCNTs were dispersed well with the increasing of dispersant-TNADIS mass fraction. The dispersion effective reached the best with adding of 0.05wt% dispersant based on carbon nanotube. The dispersion effect became worse when the dispersant content exceeded 0.05wt%.After the high temperature treatment of 1400? in the vacuum furnace, the C-C bond of MWCNTs was fractured in the reaction, and MWCNTs was decomposed.The carbon atoms diffused to metal tungsten matrix to form tungsten carbides of the mesenchymal carbide WC and W2 C. The inside carbon nanotubes in the MWCNTs aggregates can not participate in the carbonization reaction, but extremely tiny tungsten metal powder got into the aggregates during the milling process,and remained adsorbed on the surface of MWCNTs after carbonization.The one dimensional MWCNTs inserted in the WC-Co cemented carbide and located between the WC grains. Thus the WC Cemented carbide grains can be refined and WC grain growth be suppressed by MWCNTs.The strength and toughness of the cemented carbide was strengthened with the mechanisms of collaborative fiber pull out, fiber bridge, crack deflection et,al. Performance test results of cemented carbide showed that the maximum value of coercive force of 17050 A / m was obtained when doped with 0.3wt.% MWCNTs, which is 3.6% higher than the cemented carbide without addition of MWCNTs. Transverse rupture strength also reached the maximum value of 1875 MPa, which is 7.6% higher than the cemented carbide without addition of MWCNTs. Differences in the hardness of cemented carbide is relatively small when changed the content of MWCNTs from 0.1% to 0.3%. There was just a slight decline in hardness when 0.7wt% of MWCNTs was added. the hardness of cemented carbide decreased by 1.8% compared to the cemented carbidewithout the addition of MWCNTs. But the impact toughness increased significantly.When 0.3% of MWCNTs was added. The impact toughness reached the maximum value of 7.19 J/cm2. Impact toughness increased by 13.05% compared to the cemented carbide without the addition of MWCNTs.In this study, the prepared MWCNTs had good performance for dispersion. The properties of the cemented carbide doped with MWCNTs were improved and showed good comprehensive performance.