Ni/Ti(C,N)包覆粉及其金属陶瓷的制备

Preparation of Ni/Ti(C,N) Coated Powders and Cermets

采用非均相沉淀-热还原法制备Ni/Ti(C,N)包覆粉,并用该包覆粉经真空烧结制得金属陶瓷。利用扫描电镜、电子能谱、X-射线衍射等手段研究包覆粉的结构形貌及烧结后的微观组织与性能。结果表明:非均相沉淀过程中,非晶态的NiCO3·2Ni(OH)2·2H2O在Ti(C,N)颗粒表面成核并生长;经热还原过程后,NiCO3·2Ni(OH)2·2H2O分解并完全还原成Ni,Ni的平均晶粒尺寸约为50nm;采用包覆粉为原料制备金属陶瓷,有效改善了硬质相和粘结相的分布均匀性,但包覆粉烧结过程中存在晶粒长大现象;金属陶瓷的相成分为纯净的Ti(C,N)与Ni两相;金属陶瓷的综合性能相对于传统工艺制得的金属陶瓷有一定提高。

Ni/Ti（C,N） coated powders were synthesized by heterogeneous precipitation-thermal reduction process,then pressed and vacuum sintered to manufacture cermets.The chemical composition,microstructure and phases of the composite powder and the sintering microstructure and properties of the composite powder were investigated by SEM,EDS,XRD,etc.The results show that the amorphous NiCO3·2Ni（OH）2·2H2O precipitates nucleate and grow on the surfaces of Ti（C,N） powders in heterogeneous precipitation process.NiCO3·2Ni（OH）2·2H2O decomposes and then is completely reduced to Ni after thermal reduction process,and the average grain size of Ni is 50 nm.Using the coated poeders as raw materials for preparing cermets,the distribution of hard phase and binder phase in the metal cermets becomes more uniform,but the phenomenon of grain growth occurs.The phase constituents of the cermets are pure Ti（C,N） phase and Ni phase.Ti（C,N） cermets show better comprehensive properties compared to the cermets which prepared by traditional process.