STRENGTHENING OF COLD-SETTING RESIN SAND BY THE ADDITIVE METHOD

In the present work, a new additive, triphenyl phosphate, has been dev eloped to modify the cold-setting Furan resin. Experimental results sh owed that the average tensile strength of the cold-setting resin-bonde d sand was enhanced by 80-120% when 5 wt.% of triphenyl phosphate, bas ed on the weight of the resin, was added. Hence, the amount of resin a dded to the base sand can be reduced greatly in actual casting product ion. 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 fr acture to a tough fracture so that its cohesive strength is greatly en hanced. Furthermore, triphenyl phosphate also improves the distributio n of the resin amongst the sand grains and the adhesive force that mak es the resin binder adhere to the sand grains. (C) 1997 Elsevier Scien ce S.A.