Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (31권6호 359-370)

Electrolytic Boronzing on TiAl-based Intermetallic Compounds in Fused Salt of Borax, Potassium Chloride and Lithium Chloride Mixture

Na$_2$B$_4$O$_7$-KCl-LiCl 혼합용융욕에서 TiAl계 금속간 화합물의 전해붕화처리

이두환;김익범;이주호;김수식;

;인하대학교

Abstract

TiAl-based intermetallic compounds were electro-bornizel in the mixture of $Na_2B_4O_7$, KCL and LiCl in the termetature rage between 850 and $1000^{circ}C$for various times (1-5 hours)under the fixed current density of 0.5 A/$cm^2$. The optimized composition of electrolyte in this work was decided to be 76.9 wt% $Na_2B_4O_7$-19.2 wt.%(0.7KCl-0.3LiCl) -3.9 wt.% al. The samples with boronized layer were investigated by SEM, XRD and EDS. The surface micro-hardness of boronized TiAl was also evaluated using Micro Vickers Hardness Tester. The sample, boronized at $900^{circ}C$ for 4 hours in the above composition of electrolyte under the current density of 0.5 A/$ extrm{cm}^2$, has about 36$mu extrm{m}$ think layer on the surface, and its surface micro-hardness was measured to be 1263 Hv. From the results of SEM, XRD and EDS, the layer consisted of $TiB_2$ sublayer and Al-oxide sub layer. Al-depleted layer below the Al-oxide sudlayer was also detected. The activation energy for formation of boronized layer in this study was calculated as 178 Kcal/moleK.

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