非晶包覆纳米复合结构高铝AlTiSiN涂层制备的热力学反应机理及构效关系研究

TiAlSiN coating, deposited by physical vapor deposition(PVD), was widely used in cemented carbide cutting tools because of their excellent comprehensive performance. However, Al content of PVD-TiAlSiN coating is relatively low (between 20 and 45 at%), which results in a large limitation in the use of such coated cutting tools in the field of dry high speed machining. In order to increase Al content in TiAlSiN coating, based on the preparation of CVD-AlTiN coating with ultra-high Al content (Al≥65 at%) deposited by LPCVD, Si doping has been basically realized by adding SiCl4 during deposition, and CVD-AlTiSiN coating with high Al content (Al≥50 at%) has been deposited by LPCVD during the preliminary exploration experiment. However, thermodynamic reaction mechanism of CVD-AlTiSiN deposition process, and the composition, structure and properties of CVD-AlTiSiN coating have not been systematically studied. Therefore, thermodynamic calculation of the LPCVD process of AlTiSiN coating will be firstly carried out in this project, and then effect of major parameters on the composition and phase of AlTiSiN coating will be clarified, thermodynamic reaction mechanism of AlTiSiN coating deposition will be understood, the fcc-TiN/amorphous-Si3N4 nanocomposite AlTiSiN coating with high Al content (Al≥50 at%) will be successfully prepared, finally, the composition, structure and properties (hardness, oxidation resistance and thermal stability) of CVD-AlTiSiN coating with high Al content will be detailed investigated by TEM, XRD, nanoindentation and other testing methods, additionally, the relationship among composition-structure-performance will be established.

PVD-TiAlSiN涂层具有优异的综合性能，广泛用作硬质合金刀具的涂层。但是，PVD-TiAlSiN涂层Al含量较低（20-45at%），使得该类涂层在干式高速切削领域的使用受到较大的限制。为了提高Al含量，申请人在LPCVD制备超高铝AlTiN涂层（Al≥65at%）基础上，增加SiCl4气源将Si掺杂到AlTiN涂层中，初步获得了高铝AlTiSiN涂层（Al≥50at%），但是，对沉积过程的热力学反应机理、涂层成分、结构和性能尚未进行系统研究。因此，本课题将对AlTiSiN涂层的LPCVD过程进行详细的热力学计算，查明主要工艺参数对涂层成分和物相组成的影响，理解涂层沉积的热力学反应机理，制备出非晶包覆纳米复合结构的高铝AlTiSiN涂层（Al≥50at%），综合应用多种测试表征手段，系统研究涂层的成分、结构和性能（硬度、抗氧化性能和热稳定性）并建立成分-结构-性能之间的有机联系。

项目经过3年的研究，通过热力学计算和试验研究，掌握了低压化学气相沉积方法（LPCVD）主要工艺参数对AlTiSiN涂层成分和物相组成的影响，成功制备出了非晶包覆纳米复合结构的高铝CVD-AlTiSiN涂层，实际Al含量超过了80%，硬度可达38.3 GPa，该技术作为“面向难加工材料高效精密切削涂层硬质合金刀具材料关键技术及产业化”成果的重要部分，于2022年4月进行了成果评价，评价认为“其中CVD-TiAlSiN涂层技术达到国际领先水平”。综合运用X射线衍射、透射电镜、扫描电镜、纳米压痕等测试表征手段，系统研究了CVD-AlTiSiN涂层的成分、微观结构、硬度、抗氧化性能和热稳定性，建立了高铝CVD-AlTiSiN涂层微观组织结构与性能之间的有机联系。