烧结气氛对Ti(CN)基金属陶瓷组织和性能的影响

用X射线衍射、背散射扫描电镜及能谱仪等分析手段研究了烧结气氛(真空、N2、Ar)对不同成分TiC基和Ti(CN)基金属陶瓷合金显微组织和性能的影响.金属陶瓷在N2和Ar中烧结后,合金碳含量比在真空中烧结的碳含量低0.5%左右;在N2中烧结后,合金的氮含量提高了0.5%左右.环状结构心部可以是以钨等重金属元素为主要成分的碳化物,也可以是以钛为主要成分的碳化物和碳氮化物.环状结构为金属元素含量和分布不同的(Ti,W,Ta,Mo,Co,Ni)(C,N)固溶体,粘结相是与Ti,W,Ta,Mo,C,N等元素有不同溶解度的钴镍固溶体.真空烧结后组织结构比较均匀,合金的性能最好.在Ar、N2中烧结后,气氛中的氧和氮参加烧结反应,影响合金成分碳氮平衡,在合金表面形成壳层结构,产生表面缺陷,合金的密度、显微硬度、抗弯强度均有比较大的降低;N2气氛影响更大.

Effect of sintering atmosphere on structure and properties of Ti(CN) base cermets

Effect of the sintering atmospheres(vacuum,N_2,Ar) on the microstructures and properties of the TiC and Ti(CN) based cermets was studied by X-ray diffractrometry,scanning electron microscopy and energy spectrometer.Compared with the alloys sintered in vacuum,the carbon content of the cermets sintered in N_2 and Ar is lower by 0.5%;and the nitrogen content is higher by 0.5% when sintered in nitrogen.The central part of the ring structure may be either carbide with a high W content or carbonitride with a high Ti content.The ring structures are (Ti,W,Ta,Mo,Co,Ni)(C,N) solid solutions with different metallic elements and distributions.The composition of the binder phase are(Co,Ni) solid solutions with different Ti,W,Ta,Mo,C,N contents.The structures are uniform for the cermets sintered in vacuum and the properties are the best.When sintered in Ar or N_2,the O_2 and N_2 in the atmosphere take part in the sintering reaction to break the balance between the carbon and nitrogen in the cermets to form a shell structure and defects,which result in poor density,microhardness and transverse rupture strength.