Basic research on electroforming of Fe–Ni shell with low thermal expansion

Traditional mold metal always has a high thermal expansion coefficient which cannot satisfy the demand for composite material component mold making. Therefore, in order to get a cylindrical shell in thicker, large size, and low thermal expansion property for mold making, fundamental experiment of electrodeposited Fe–Ni alloy was performed on a cylindrical cathode with different rotary speeds and current densities. The composition, micro-structure, thermal expansion property, and mechanical properties were tested after deposition. The results showed that with the decreasing in current density and increasing in cathode rotary speed, the thermal expansion coefficient, micro-hardness, and tensile strength are decreasing while the iron content represents an upward trend. Due to the application of rotating cathode speed ranging from 10 to 60 r/min, the thermal expansion coefficient of alloy can be adjusted between 7.6 and 13.3 × 10 −6 /°C. In cathode rotary speed of 60 r/min, a good quality Fe–Ni alloy cylindrical sample of 64 wt.% iron contents, hardness 558 HV, tensile strength 1364 MPa, and thermal expansion coefficient 7.6 × 10 −6 / ° C can be obtained at a comparatively high current density 6 A/dm 2 .