In this Master thesis we have explored the field of thermal and chemical properties of water-based coatings with added sol-gel component. Coatings with an added sol-gel component have improved rheological properties, thus improving the application and adhesion of the coating on the surface of sand molds and cores. The mold or core coating creates a high thermal integrity barrier between the metal and the mold in the reduction of the thermal shock experienced by the sand system. The fundamental requirements for refractory coatings are minimum porosity, high refractoriness and reduction of the physicochemical reaction at the metal-coating interface (lubrication, solution, penetration). Optimization of the composite coatings to satisfy all the above requirements can be achieved by adding the sol-gel component.
The use of the sol-gel process in the production of foundry coatings has been a new technology. Recent studies in coatings technology indicate that the addition of sol-gel components significantly improves the surface of castings; important role also has a ratio of sol relative to other components. The added sol-gel component reduces the viscosity of the coating, which improves its properties (lubricity) and consequently gives a better surface of the casting. The purpose of the present master's thesis was to investigate the effect of using the sol-gel component as an additive to the water-based coating with zircon filler.
We studied the influence of three chemically different sol-gel components on the surface of castings, and at the best, the influence of various mass ratios between the basic coating and the sol-gel component. The results indicate that the use of the sol-gel component significantly improves the surface quality of castings.