Recent years have seen extensive use of monolithic linings of steel-teeming ladles in metallurgical factories [1-5, etc.].In 1980 more than 18,000,000 tons of steel were poured through ladles with monolithic linings.Like brickwork, a monolithic lining does not wear uniformly:Wear is most intense in the region of the slag belt and at the bottom of the ladle [i, 3, etc.].In the preparation of a lining by pouring refractory concrete a method has been developed for its repair by "addition"; this ensures that the duration of the lining campaign reaches 100-120 pourings before complete replacement [6,7]. The durability of the tamped lining can be increased by the use of guniting [i].An important factor in guniting efficiency is the adhesion of the paste to the surface being repaired; this is largely determined by its wetting with the liquid phase of the gunite mass.In the case of guniting with semidry masses the liquid phase is a suspension of aqueous solutions of additives, particles of technological binders and the filler.The contact angle of wetting of the vitrified surface of a siliceous monolithic lining by aqueous solutions of water glass, alcoholic sulfite waste (a.s.w.), water-soluble chromium compounds, and suspensions based on these solutions with additions of refractory clay and chamotte was determined by the sessile-drop method [8] at 20-200~After attainment of the test temperature, a drop was placed on the substrate and the process recorded on motion picture film.Up to 100~ the contact angle of wetting did not change during the residence period. At higher temperatures it decreased, due to evaporation of water from the drop, the area of its contact with the substrate remaining unchanged. Figure 1 shows the contact angles of wetting of the surface of a vitrified monolithic lining by solutions of additives.The influence of the solution concentration on the contact angle of wetting is complex and depends on temperature.When refractory clay and chamotte are added to the solutions the above regularities are retained and only the absolute values of the contact angle change. The most effective additive for guniting is water glass.The adhesion of the gunite layer to the lining was determined on specimens of masses of chamotte, silica, and periclase--chromite compositions.The masses were wetted with an aqueous solution of a.s.w, to a moisture content of 8-10%, deposited onto the vitrified surface of the monolithic lining, compacted at a pressure of i0 MPa, and subjected to heat treatment at 700, 900, and 1200~The results showed (Table i) that a ceramic bond is formed only after heat treatment at 900~ or above.On the basis of determination of the compression strength, the change in the linear dimensions during annealing, the open porosity, and apparent density of specimens of 90%* roasted bauxite and 10% DNPKI clay, heat-treated at 500-1600~ the following grain-size composition of the gunite mass can be recommended: not more than 5% of the fraction larger than 2 mm, 20-20% of the 2-1 mm fraction, 20-30% of the 1-0.5 ...
