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采用电弧离子镀技术在YW2硬质合金基体上沉积了厚度为2μm的TiN涂层,对所获得的TiN/YW2体系进行了-196℃下30 h的深冷处理。采用X射线衍射仪(XRD)和显微硬度仪分别对深冷前后TiN涂层的相结构和硬度进行了检测,利用洛氏硬度仪采用压痕法研究了深冷处理前后YW2基体和TiN/YW2体系压痕形貌的变化,借助金相显微镜和扫描电镜(SEM)研究了基体显微组织及其对体系断裂韧性、界面结合状况的影响。结果表明:深冷处理后涂层中应力诱导晶粒扭转导致的TiN(111)面择优取向,使体系的硬度得到了提高。基体上压痕径向放射性裂纹密度明显降低,TiN涂层沿压痕周向的块状剥离得到缓解。深冷处理后弥散分布的颗粒状γ相显著减少或消失、孔隙率降低,组织变得更加致密,加之深冷处理过程中裂纹源的弥合,提高了YW2基体和TiN/YW2体系的断裂韧性和界面结合强度。
The TiN coating with a thickness of 2μm was deposited on YW2 cemented carbide substrate by arc ion plating. The obtained TiN / YW2 system was cryogenically treated at -196 ℃ for 30 h. The phase structure and hardness of TiN coating before and after cryogenic treatment were measured by X-ray diffraction (XRD) and microhardness tester. The indentation method was used to study the phase structure and hardness of TiN / TiN / YW2 matrix before and after cryogenic treatment using Rockwell hardness tester. System indentation morphology changes, the use of metallographic microscope and scanning electron microscopy (SEM) study of the matrix microstructure and fracture toughness of the system, the impact of interface bonding. The results show that the preferential orientation of TiN (111) surface caused by stress induced grain torsion in the coating after cryogenic treatment increases the hardness of the system. The radial radioactive crack density of the indentation on the substrate is significantly reduced, and the TiN coating is relieved along the circumferential direction of the indentation. After cryogenic treatment, the dispersed and dispersed granular γ phase decreased or disappeared significantly, the porosity decreased and the microstructure became denser. In addition, the crack sources and interfacial bonding between YW2 matrix and TiN / YW2 system were improved strength.