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等离子烧结制备工艺对WC/Cr3C2/La2O3刀具材料力学性能的影响

Effect of plasma sintering preparation process on the mechanical properties of WC/Cr3C2/La2O3 cutting tool materials

  • 摘要: 针对传统硬质合金刀具高速切削过程中粘结相易于磨损等问题,采用等离子烧结制备了WC/Cr3C2/La2O3刀具材料,研究Cr3C2含量和烧结工艺参数对刀具材料微观组织和性能的影响。分别对Cr3C2含量0 wt%~2 wt%、烧结温度1500 ℃~1700 ℃和烧结压力15 MPa~45 MPa下制备的样品测试后,结果表明,Cr3C2添加量为0.5 wt%,在1550℃和25 MPa条件下烧结,材料的致密度、硬度和抗弯强度分别为97.5%、2124.3 HV和1281.0 MPa。随着烧结温度增加,材料的致密度增加和微观组织逐渐均匀,而过高温度导致晶粒异常长大、组织分布不均、孔隙增多和综合力学性能下降。随着烧结压力增加,材料晶粒细小,组织更加均匀,力学性能增加。当压力超过25 MPa后,材料力学性能有所下降。

     

    Abstract: Traditional cemented carbide tools with binder phase is easy to be worn under high-speed cutting. In order to improve tool life, WC/Cr3C2/La2O3 cemented carbide without binder phase was prepared by Spark Plasma Sintering.The effect of chromium carbide content, sintering process on the microstructure and properties of sintered specimens were investigated. After testing the samples prepared at Cr3C2 content of 0 wt%~2 wt%, sintering temperature of 1550 ℃~1550 ℃ and sintering pressure of 15 MPa~45 MPa, respectively, the results show that the optimum chromium carbide content is 0.5 wt%. WC/Cr3C2/La2O3 cemented carbide sintered at 1550 ℃ and 25 MPa has the best comprehensive properties.The density, Vickers hardness and bending strength are 97.5%, 2124.3HV and1281.0 MPa, respectively. With the increase of sintering temperature, the density increases and microstructure becomes more even for WC-based tool materials. However, too high temperature leads to abnormal growth of grains, uneven distribution of microstructure, more porosity and lower mechanical properties.As sintering pressure increases, the size of the grains reduces, the microstructure is more even and mechanical properties increase. While sintering pressure is above 25 MPa, mechanical properties of tool materials decrease.

     

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