| 摘要 |
<p>Protective coating for the surfaces of workpieces exposed to extreme heat, e.g. ends of oxygen lances for steel making, comprises particles of metal carbides with high m. pt. are bonded or melted into the workpiece surface. Particles are pref. tungsten carbide esp. grains with dia. 0.5-5 mm esp. 3 mm, bonded in a layer of material which is either the same as the substrate or forms a homogeneous cpd. with the substrate. A buffer layer may also be used between the layer contg. the carbide and the substrate, forming a homogeneous cpd. with both. Carbide and its bonding layer are pref. obtd. by deposition welding, esp. using inert gas and/or a flux, and arc welding using a tungsten electrode, and a filler rod. Alternatively the carbide particles can be located in a mould which is then filled by a metal to form a cast workpiece with a carbide surface layer. Filler rod used in welding pref. contains carbide particles and a flux.</p> |
