低温固体硼碳氮稀土共渗及其机理探讨

研究了低温硼－碳－氮－稀土（Ｂ－Ｃ－Ｎ－ＲＥ）共渗工艺及共渗层的组织性能，并与硼－碳－氮（Ｂ－Ｃ－Ｎ）共渗工艺及共渗层的组织性能进行了比较，结果表明，低温共渗的硼化物层由ＦｅＢ、Ｆｅ２Ｂ、Ｆｅ３（Ｃ，Ｂ）等相组成，硼化物层的前沿无过渡区，ＦｅＢ和Ｆｅ２Ｂ生长过程中排挤出来的碳没有发生远程扩散，而是就近形成Ｆｅ３（Ｃ，Ｂ）等形式的硼化物。稀土加入量适当时，具有明显的催渗作用；与Ｂ－Ｃ－Ｎ共渗相比，Ｂ－Ｃ－Ｎ－ＲＥ共渗层的耐磨性和耐蚀性明显提高。对Ｂ－Ｃ－Ｎ－ＲＥ共渗的机理及稀土元素的作用作了初步的探讨。

Low Temperature Powder B-C-N-RE Co-cementation and its Mechanism

In this paper the process,the structure and properties of low temperature powder B-C-N-RE co-cementation are studied and compared with the boro-carbonitriding.The results show that the layer consists of such phases as FeB,Fe 2B and Fe 3(C,B),and no transitional zone exists between the layer and the substrate.The carbon atoms repelled during the formation of FeB and Fe 2B could not diffuse for long distance because of the low treating temperature.They formed Fe 3(C,B) within the co-cementation layer.An significant catalytic effect of the rare earth elements can be obtained when proper amount of rare earth is applied.Both wear and corrosion resistances of the B-C-N-RE co-cementation layer are improved significantly in comparison with that of boro-carbonitriding.The mechanism of B-C-N-RE co-cementation and the effects of rare earth elements are discussed.