چكيده به لاتين
Abstract:
Boronizing is a thermo-chemical surface hardening process in which boron atoms diffused in substrate material create a metal boride layer with high hardness and corrosion resistance. The aim of this study was the evaluation of structure and properties of sintered W-Ni-Fe heavy alloy after boronizing. The surface treatment was done via pack cementation method in a box consisted of B4C, KBF4 and SiC powders. 6 tungsten alloyed sample were treated in a compound powder involved of 5 wt% B4C, 5 wt% KBF4 and 90 wt% at three temperature, 1000, 1050 and 1100 °C, during 6 and 9 hours. XRD, SEM, ICP-MS and Vickers microhardness were used to assess phase structure, layer thickness, elemental analysis and hardness of boronized surface, respectively. Three regions were observed in the surface. The first one was mostly nickel silicide. The second region was the reaction zone consisted of taungestan particles layered by WB. The last region did not interfere in the reaction. Increase in temperature increase the depth of reaction region and consequently, however, improve surface hardness but decrease surface quality which caused by variation in ductile nickel-rich matrix alloy. The highest hardness, 2531.67 HV, was obtained at 1000 °C and after 9 hours treatment. According to the depth of reaction zone, 1000 °C and 9 hr are the optimized conditions.
Keywords: Boronizing, Tungsten heavy alloy, Pack cementation method, microhardness, ICP-MS
