脱β层厚度对CVD涂层硬质合金性能的影响

通过对WC-TiC-(Ta,Nb)C-Co硬质合金在1 300～1 380℃的渗氮气氛处理和随后的脱N烧结制得了不同脱β层厚度的合金基体,通过化学气相沉积(CVD)工艺制成从内到外依次为TiN/MT-TiCN/Al2O3/TiN的涂层硬质合金。采用光学显微镜、扫描电镜和能谱仪、抗弯(TRS)和切削试验对合金基体涂层前后的组织特征与性能进行了研究。结果表明,随着脱β层厚度的增加,试样涂层前后的抗弯强度均增加,在厚度达到20μm以上时,增加不明显。CVD涂层硬质合金可转位刀片的抗冲击性能也有相应的规律,而耐磨性则基本上保持一致。

Influences of Cobalt-rich Layer Thickness on Properties of Coated Cemented Carbide

The cemented carbide matrix with different thickness of cobalt-rich layer was prepared by nitriding WC-TiC-（Ta,Nb）C-Co cemented carbide at 1 300 ~ 1 380 ℃ followed by sintering for nitrogen removal.The TiN/MT-TiCN/Al2O3/TiN coating（from inside to outside） was coated on the matrix by chemical vapour deposition（CVD）.The microstructure and mechanical properties of the cemented carbide matrix before and after coating were researched by OM,SEM,EDS,TRS and cutting test.The results indicate that the TRS values of the alloy before and after coating all increase with the increasing of the cobalt-rich layer thickness.When the thickness of the cobalt-rich layer exceeds 20 μm,the increase of the TRS is not obvious.The impact resistance of the CVD coated cemented carbide inserts has the same rule as the TRS,but the wear resistance doesn＇t vary too much.