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研究了Na_2B_4O_7-SiC型共渗剂中添加铁粉、铁丝和扎铁丝方式对TC4钛合金表面盐浴硼氧共渗的影响。采用金相显微镜(OM)、扫描电子显微镜(SEM)及其配备的能谱仪(EDS)、X射线衍射仪(XRD)以及显微硬度计,分析了共渗层表面形貌、物相组成和表面硬度;采用化学热力学分析讨论了铁粉型和铁丝型共渗剂无明显催渗作用的原因,采用电化学模型解释了扎铁丝对盐浴硼氧共渗的催渗机理。结果表明,各组共渗层具有较好的表面形貌,组织均匀;渗层主要由TiB、TiB_(12)、Ti_2B_5和TiB_(25)等钛硼化合物以及TiO_2和TiC相组成;硼砂—碳化硅型、铁粉型和铁丝型共渗层表面硬度依次为677、673和680 HV,性能相似;而扎铁丝型共渗剂中形成电化学效应,具有更好的表面质量,主要由TiB、TiB_(12)、TiC和Al_2O_3相组成,更高的表面硬度(989 HV),比TC4钛合金基体硬度提高了2.75倍,比碳化硅型表面硬度提高了46.04%。
The effects of adding iron powder, iron wire and barbed wire on the surface salt bath boro-oxygenation of TC4 titanium alloy were studied in Na_2B_4O_7-SiC type infiltrating agent. The surface morphology and phase composition of co-diffusion layer were analyzed by OM, SEM and EDS, X-ray diffraction (XRD) and microhardness tester And surface hardness. The reason of no obvious catastrophic effect on the iron powder and wire-type infiltrating agent was discussed by chemical thermodynamic analysis. The electrochemical mechanism was used to explain the mechanism of bar-wire on the borosilicate osmosis of salt bath. The results show that the alloying layers have good surface morphology and uniform microstructure. The diffusion layer is mainly composed of TiB, TiB 12, Ti 2 B 5 and TiB 25 and TiO 2 and TiC phases. The surface hardness of silicon type, iron type and wire type co-diffusion layer are 677, 673 and 680 HV, respectively, with similar properties. However, the electrochemistry effect in barbed wire type infiltrating agent has better surface quality and is mainly composed of TiB, TiB_ (12), TiC and Al_2O_3 phases, higher surface hardness (989 HV), which is 2.75 times higher than that of TC4 titanium alloy substrate and 46.04% higher than the surface hardness of silicon carbide.