Strengthening of cold-setting resin sand by the additive method

In the present work, a new additive, triphenyl phosphate, has been developed to modify the cold-setting Furan resin. Experimental results showed that the average tensile strength of the cold-setting resin-bonded sand was enhanced by 80–120% when 5 wt.% of triphenyl phosphate, based on the weight of the resin, was added. Hence, the amount of resin added to the base sand can be reduced greatly in actual casting production. Consequently, both the gas evolution and the deformability of the cold-setting resin sand were also improved and high-quality castings with lower porosity and cracking could be obtained. The strengthening mechanism of the cold-setting resin sand by triphenyl phosphate mainly lies in that fracture of the resin film has changed from a brittle fracture to a tough fracture so that its cohesive strength is greatly enhanced. Furthermore, triphenyl phosphate also improves the distribution of the resin amongst the sand grains and the adhesive force that makes the resin binder adhere to the sand grains.