Nb添加量对金属陶瓷显微组织和磁学性能的影响

Effect of Nb Additions on the Microstructure and Magnetic Properties of the Cermet

Ti(C,N)基金属陶瓷具有硬度高、耐蚀性好及密度低等一系列优点,在工业领域具有广泛的应用前景。但它室温时易呈铁磁性,阻碍了其进一步推广应用。采用粉末冶金法制备了系列TiC-l0TiN-xNb-30Ni-4C(摩尔分数)金属陶瓷,用X射线衍射仪(XRD)、扫描电镜(SEM)、振动样品磁强计(VSM)、物理性能测试系统(PPMS)、洛氏硬度计和万能试验机研究了金属陶瓷的磁学性能、力学性能以及显微组织在不同Nb添加量下的变化。结果表明,所有金属陶瓷由陶瓷晶粒和Ni基粘结相组成,添加的Nb组元在烧结过程中基本完全固溶于粘结相和陶瓷相。整体上,陶瓷晶粒随着Nb添加量的增加变细。未添加Nb的金属陶瓷呈现典型的铁磁性,当Nb添加量为8%(摩尔分数)时,金属陶瓷转变为顺磁性。随着Nb添加量的增加,Ti(C,N)基金属陶瓷的室温饱和磁化强度和剩磁都呈现下降趋势,然后逐渐趋近于0。Nb含量的增加,也使得Ti(C,N)基金属陶瓷的抗弯强度和硬度呈现先增加后逐渐减小的趋势。当Nb含量为4%(摩尔分数)时,Ti(C,N)基金属陶瓷保持较好的抗弯强度(1 470 MPa)和硬度(87.0 HRA)。研究可为制备无磁金属陶瓷提供一定的理论依据。

Ti(C,N)-based cermet has a series of advantages,such as high hardness,good corrosion resistance and low density,and have a wide application prospect in the industrial field.However,Ti(C,N)-based cermet is easy to be ferromagnetic at room temperature,which hinders its further popularization and application.In this paper,a series of TiC-l0TiN-x Nb-30Ni-4C(mole fraction)cermet materials were prepared by powder metallurgy.The magnetic properties,mechanical performance,and microstructure of metal ceramics were investigated using X-ray diffractometry(XRD),scanning electron microscopy(SEM),vibrating sample magnetometry(VSM),a physical properties testing system(PPMS),rockwell hardness tester,and a universal testing machine.The study examined the effects of varying Nb additions on these properties.The results indicate that all cermet materials consist of ceramic grains and a Ni-based binder phase,and the added Nb component is basically completely dissolved in binder phase and ceramic phase during sintering.On the whole,the ceramic grains become finer with the increase of Nb addition.The cermet materials without Nb show typical ferromagnetism,and when the amount of Nb is 8%(mole fraction),the cermet materials turn into paramagnetism.The increases in Nb content also led to a trend in which the flexural strength and hardness of Ti(C,N)-based cermet materials initially increased and then gradually decreased.The bending strength and hardness of Ti(C,N)-based cermet materials exhibit an initial increase followed by a gradual decrease with the rise in Nb content.When the content of Nb is 4%(mole fraction),Ti(C,N)-based cermets have good bending strength(1470 MPa)and hardness(87.0 HRA).The research in this paper may offer a theoretical foundation for the fabrication of non-magnetic cermet materials.