Boronizing Treatment, Using MoB, B₄C and NiB Powders, of Sintered Mo-Ni Powder Compacts

Abstract

The effects of boronizing conditions in sintered Mo-Ni powder compact were investigated, which was treated with the mixed powders; MoB, B₄C, NiB as a B element supply and NH₄Cl, BaF₂, Na₂CO₃ in activitor.
The results obtained were as follows;
(1) The thickness of boride layer of all specimens increased with increasing boronizing temperature and time.
(2) Line analysis patterns of the EPMA showed that the boride layers in sintered Mo-Ni powder compacts were clearly recognized in the cases of MoB and B₄C powders.
(3) The X-ray diffraction showed that the boride layers of sintered Mo powder compacts consisted of three phases of MoB, Mo₂B and Mo₂B₅.
(4) Effect of activitors showed that the existence of each phase of MoF₃ and of MoCl₂ was recognized by the X-ray diffraction, when using the NH₄Cl and BaF₂ in activitors.
(5) NiB powder tested in B element supply was not suitable to increase the thickness of boride layer.