TECHNOLOGICAL VARIANTS FOR DEPOSITION OF HARD LAYERS ON THE ACTIVE SURFACES OF THE COAL HAMMERS MILLS

The paper presents several methods of hard alloys deposition on the surfaces of coal and rock crush hammers. Structural and mechanical characteristics of the hard rocks impose to be chosen hard alloys to achieve deposition layers which will help to increase the life time of the metallic hammers made by cast weldable steels type 340-550 W according to ISO 3755.As deposition materials were used (307 FILINOX wire, FLUXOFILM 58 tubular wire FILEUR AMC-60 tubular wire and HARDFACE TIC tubular wire) and nickel-based powders (METCO 450P) with the maximum hardness of 739 HV5 and ceramics based powders (METCO 105NS-Al(2)O(3)) obtaining hard layers whose hardness varies between 549 and 841 HV5 with the maximum thickness of 238.5 mu m. The analysis in terms of structure/hardness/thickness of the deposited layers allowed the selection of the optimum hardening variant using HARDFACE TIC tubular wire, obtaining layers without defects on the crush hammers surfaces.