烧结温度对WC-Co-Ti3SiC2硬质合金微观组织与力学性能的影响

The Effenct of Sintering Temperatures on Microstructures and Mechanical Properties of WC-Co-Ti3SiC2 Cemented Carbides

摘要:

本文以掺杂3.0wt.% Ti3SiC2的WC-Co-Ti3SiC2硬质合金为对象，研究了烧结温度（1350~1470 ℃）对WC-Co-Ti3SiC2硬质合金中的Ti3SiC2分解物相和比例、微观组织、及其力学性能的影响规律与机制。结果表明：烧结温度的升高，促进了WC-Co-Ti3SiC2硬质合金中Ti3SiC2的分解以及(W,Ti)C和WSi2相的生成，同时导致WC晶粒尺寸逐渐增大。硬质合金的硬度随烧结温度的增加呈现出先增大后降低的趋势，而断裂韧性则逐渐下降。当烧结温度为1410℃时，WC-Co-Ti3SiC2硬质合金的致密性最佳（孔隙率仅为0.47 %），其力学性能也较为优异，硬度与断裂韧性分别为2076.36 kgf/mm2和10.15 MPa·m1/2。进一步分析可知，WC-Co-Ti3SiC2硬质合金硬度的增加归因于合金内部致密性的提高，而硬质合金中脆性相(W,Ti)C和WSi2含量的增加则会造成其断裂韧性的降低。

Abstract:

Taking the WC-Co-Ti3SiC2 cemented carbide dropped with 3.0wt.% Ti3SiC2 as the case, the effect of sintering temperatures (1350~1470 oC) on the microstructure, density and mechanical properties of WC-Co-Ti3SiC2 cemented carbide were investigated. The results show that as sintering temperatures increase, the fractions of decomposed Ti3SiC2 as well as volume fractions of (W,Ti)C and WSi2 phases in as-received WC-Co-Ti3SiC2 cemented carbides gradually increase. Meanwhile, the increase of sintering temperature results in the increase of the WC mean grain size. The hardness of WC-Co-Ti3SiC2 cemented carbides increases and then decreases with the increase of sintering temperature, while the fracture toughness decreases gradually. When the sintering temperature is 1410 oC, the density of WC-Co-Ti3SiC2 is optimum, and the porosity is 0.47 %. Meanwhile, the 1410 oC is optimum sintering temperature for the mechanical properties of WC-Co-Ti3SiC2 cemented carbides. The hardness and fracture toughness are 2076.36 kgf/mm2 and 10.15 MPa·m1/2, respectively. The enhancement in hardness is attributed to the increase in density of cemented carbides, while the reduction in fracture toughness result from the increase in the content of brittle phases (W,Ti)C and WSi2 in the cemented carbide.