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氢气脱氧预烧结+放电等离子烧结”两步法制备低氧高致密超细晶钼金属研究

Research on the Preparation of low-oxygen, high-density and ultra-fine grained Mo Metal by a Two-step Method of “Hydrogen Deoxidation Pre-sintering + Spark Plasma Sintering”

  • 摘要: 本研究以超细钼粉(0.4 μm)为原料,采用氢气脱氧预烧结+放电等离子烧结的两段式烧结法制备了高强度细晶钼。研究发现,通过在1000 ℃的氢气中预烧结2 h,氧含量从超细钼粉的0.237 wt%降低至0.066 wt%。预烧结后形成了大量烧结颈,晶粒尺寸没有明显增大。然后将预烧结样品在1200 ℃下进行放电等离子烧结(SPS),烧结压力为50 MPa,烧结时间10分钟。在SPS烧结过程中,样品经历了致密化烧结,相对密度达到了99.2%。由于SPS烧结温度较低(1200 ℃),钼晶粒没有出现显著生长,平均晶粒尺寸为0.88 μm。得益于较低的氧含量、较高的相对密度、以及较小的晶粒尺寸,钼金属的维氏硬度和抗弯强度分别为300 HV和523 MPa。然而,降低SPS温度至1100 ℃会导致样品烧结不充分,相对密度仅为91.3%,维氏硬度和抗弯强度分别降低至215 HV和343 MPa。提高SPS烧结温度至1300 ℃导致晶粒尺寸显著增大至6.95 μm,维氏硬度和抗弯强度分别降低至197 HV和467 MPa。

     

    Abstract: In this work, ultrafine Mo powder (0.4 μm) was used as the raw material, and a two-stage sintering method composed of deoxidation pre-sintering and Spark Plasma Sintering (SPS) was employed to prepare fine-grained and high-strength Mo metal. The oxygen content decreased from 0.237 wt% of the Mo powder to 0.066 wt% after pre-sintering in H2 at 1000 °C for 2 h. It was found that a large number of sintering necks were formed in the pre-sintered skeleton, and the grain size did not increase significantly. Then, the pre-sintered skeleton was sintered by SPS at 1200 °C with a pressure of 50 MPa for 10 min. The Mo skeleton was sintered and the relative density of the product reached 99.2%. Due to the relatively low SPS sintering temperature (1200 °C), the average grain size was 0.88 μm, which is not grow significantly. Benefiting from the low oxygen content, high relative density, and small grain size, the Vickers hardness and bending strength of the Mo metal prepared in this work were 300 HV and 523 MPa, respectively. However, increasing the temperature to 1100 °C makes it difficult to sinter the sample, and the relative density is only 91.3%, and the Vickers hardness and bending strength decreased to 215 HV and 343 MPa, respectively. Increasing the SPS sintering temperature to 1300 °C caused the grain size to increase significantly to 6.95 μm, and the Vickers hardness and bending strength decreased to 197 HV and 467 MPa, respectively.

     

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