陈芝强　方海旋　杨晋伟

摘 要 采用不含氮的硬质合金原料，在梯度烧结工艺前添加一步微压氮化烧结工艺，制备出4种不同钴含量的脱β层梯度硬质合金，并研究钴含量对其物理力学性能和微观组织结构的影响。结果表明：随着钴含量的增加，合金密度降低，矫顽磁力减小，磁饱和强度增大，在钴含量较高、孔隙度较低且几乎不存在非化合碳时合金具有较高的抗弯强度。钴含量较低时，合金芯部立方相内部残留的未溶解的TiC 核心数量较多，钴含量过高时在界面附近靠近梯度层一侧容易出现钴相聚集现象。钴含量增大时，脱β层的厚度随之增大，但是稍低于类似条件下采用含氮原料制备的梯度硬质合金。

关键词 梯度硬质合金 ；脱β层 ；不含氮原料 ；钴含量

中图分类号 TG135+5

Effect of Cobalt Content on the Graded Cemented Carbide

of Cubic Carbide Free Layer（CCFL）

CHEN Ziqiang FANG Haixuan YANG Jinwei SHI Liuyong

（Mechanical and Electrical Engineering College， Hainan University， Haikou， Hainan 570228）

Abstract The micro pressure nitriding sintering （MPNS） was applied before conventional graded sintering procedure. Four types of graded cemented carbides with different Co content were prepared by graded cemented carbide without nitrogen. The effect of Co content on the physical mechanical properties and microstructure were investigated. The results showed that with increasing Co content，the density and coercive force decreased， magnetic saturation increased. The high-level transverse rupture strength could be obtained with high Co content， low degree of porosity and free carbon. Much number of undissolved TiC core exited inside the cubic carbide phases across the core area in the occasion with lower Co content. The phenomenon of aggregation of Co phases was inclined to arise at the side of gradient layer near the interface in the occasion with higher Co content. The depth of CCFL increased significantly with the rising of Co content， However， it was still lower than that of graded cemented carbide prepared with addition of TiN and TiCN powders under similar sintering conditions.

Key words Graded cemented carbide ； cubic carbide free layer（CCFL） ； raw powders free nitrogen ； Co content

脱β层梯度硬质合金是一类表层含一定厚度的脱β层（又称无立方相层，Cubic Carbide Free Layer，CCFL）的功能梯度硬质合金。由于其具有良好的韧性，脱β层梯度硬质合金多应用于涂层刀片的基体材料，可以降低涂层沉积过程中的裂纹倾向，并在使用过程中能有效地阻滞裂纹向合金内部扩展，延长涂层刀片的使用寿命[1]。近年来，国内外不少学者从合金的制备工艺[2-4]、影响因素[5-9]及脱β层的形成机理[10]方面对该类梯度硬质合金进行了深入研究。但以往的研究工作多采用含氮硬质合金原料，即在普通硬质合金原料中直接添加含氮的硬、脆立方相，如TiN或Ti（C，N），这些含氮相在存在碳化物的情况下稳定性较差，烧结过程中特别容易提前分解、产生氮气，从而导致合金致密度的降低，进而削弱合金整体的力学性能。……