Study On The Application Of Inorganic Binder Sand In High Efficiency Core-Making Process Of Automobile Casting

As the automobile castings are thin-walled,accurate and complex high grade castings,Many requirements for sand cores are put forward such as high strength,good fluidity,fast curing speed,high dimensional accuracy and excellent collapsibility.Therefore,the TEA-cold core box process has been widely used,however,during the core-making and pouring,a large number of benzene,aldehydes,sulfur and other toxic gases will be released,thus having the demerits causing adverse effect on the working environment.In recent years,with the continuous implementation of the national environmental protection laws and regulations,as well as increasingly strengthening of the health and environmental protection concept,a new type of binder with good environmental protection performance and low production cost is urgently needed.Thus,in the late twentieth century abroad,especially in Germany,an inorganic binder sand based on water glass is developed,and has been successfully applied to automobile castings.The newly developed water glass-based inorganic binder after hardening is a three-dimensional three-dimensional structure of the aluminosilicate inorganic polymer,the core of the composition of the main sand by the modified water glass,strong alkali?Hardener?,nano-silicon cross-linking agent,rheological agents and dispersants and other components.This inorganic binder is an inorganic polymer binder which is formed by the action of an activator?hardener?so that the sodium silicate molecules are polymerized and hardened under the action of a crosslinking agent to form a three-dimensional network structure.High viscosity sodium silicate sand flow,through the use of potassium ions on the sodium silicate solution modification and the addition of appropriate flow additives and other measures,the water glass sand flow to 3.5g or more,to meet the thin Wall,complex car castings of the sand core of the filling requirements.From the inorganic binder modification,curing methods to change and adjust the process parameters and other aspects to improve the sand resistance of the moisture and storage.The following measures can be used to improve the collapse of the inorganic binder sand:?1?adding organic matter and phosphorus,aluminum inorganic water glass modified;?2?increase the water glass modulus,reduce the amount of Na₂O;?3?in the water glass binder The addition of heat to release the H₂O or CO₂gas carbonate or swellable material,so that after pouring in the bond film to produce a large number of cracks and loss of bonding capacity,improve the collapse of the core sand capacity.