COATING OF BOILER TUBES

摘要

1481678 Coated steel tubes EUTECTIC CORP 9 April 1976 [11 April 1975] 14556/76 Heading F2P [Also in Division C7] Steel boiler tubes are coated with a layer of 10-70 wt. per cent of a refractory compound dispersed in 30-90 wt. per cent of a Ni-base, Ni-Cu-base, Fe-base, or Co-base alloy containing 0À3-6À0 wt. per cent Si and/or 0À05-5À0 wt. per cent B, the layer being fused into the tube surface. The refractory compound is selected from the carbides of W, Si, V, Ti, B, Cr, Mo; nitrides of Si, B, Ti; borides of Cr, Mo, W, Ta, V; and silicides of B, Mo, Nb, the preferred compound being WC. Examples are given of suitable matrik alloys. The layer is preferably deposited by flame spraying, the fusing being effected simultaneously or by subsequent treatment with a torch or in a furnace. In the examples, a mix of 60 wt. per cent WC and 40 wt. per cent Ni-Cr-Fe-Si-B alloy is sprayed on to grit-blasted tubes, the tubes in Example 2 being welded to form a panel.