| 摘要 |
A paving- or road-surfacing slab is cast from a martensitic Cr-Ni cast iron with hardness up to 700 Brinell throughout its thickness. The slab has, in its upper surface, frusto-conical recesses of greater cross-section at their base than at the surface. The recesses are filled with a material of desired colour and consisting of a pulverised material, partic. a ceramic, with a plastics binder. Pref. cast iron contains (by wt.) 3.3%C, 0.5% Si, 0.7% Mn, 4.5% Ni and 2.5% Cr and the filler may be based on quartzite, alumina or marble if a white colour is required, or on corundum or diabase for a black colour. The slabs may be produced by casting the iron into a disposable mould formed of rigid plastics foam, filling the recesses by high press. injected and then heating the slabs to 125 degrees C for 2 hrs. to harden the filler. The slabs are partic. intended for incorporation into road surfaces at pedestrian crossings and to indicate the location of stop signals. They are extremely wear-resistant, partic. to studded tyres. |
