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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/dm2. [ABSTRACT FROM AUTHOR]

The electrochemical mechanism of Fe-Ni electrodeposition under ultrasonic was investigated by electrochemistry methods. Linear scanning voltammetry and cyclic voltammetry were used to show that the deposition process changed from the diffusion control under static conditions to an electrochemical control under ultrasonic conditions. Chronoamperometry curves showed that the Fe-Ni deposit occurred by a mechanism that instantaneous nucleation is followed by three-dimensional growth under charge transfer control. Chronopotentiogram indicated that because of the intensity of the ultrasound stripping effect, high ultrasonic power is unsuitable for electroforming Fe-Ni alloy, and a high current density is also not appropriate. Thus, the optimum parameters for Fe-Ni electrodeposition under ultrasonic conditions are ultrasonic power between 80 and 100 W (power density 0.28–0.35 W/cm2), and a current density lower than 10 mA/cm2 with temperature 323 K and pH 3. Experiments were performed to verify that the Fe-Ni masks prepared by ultrasonic-assisted electroforming had a good surface quality. The increase in ultrasonic power can obtain a larger grain size, thus got a low thermal expansion coefficient and a high hardness. Therefore, ultrasonic-assisted electrodeposition technology provides an effective and practically feasible manufacturing method for OLED Fe-Ni mask preparation. [ABSTRACT FROM AUTHOR]

• Fe-Ni film with smooth surface could be electrodeposited at high current density due to the reducing of internal stress of film by ultrasonic power. • The iron content, grain size, micro-hardness and Young's modulus of film all present an upward trend with ultrasonic power increases from 13 W to 93 W, and then a downward trend due to the intensively transient cavitation caused by higher ultrasonic power 120 W. • With the ultrasonic power of 93 W and current density of 1 A/dm2, a good surface quality of Fe-Ni films with 60.07 wt.% iron content, microhardness 351 HV, Young's modulus 167.5 GPa and CTE 3.38 × 10−6/°C can be electrodeposited. Fe-Ni alloy is considered as the most suitable metal for OLED mask making due to its excellent properties. However, electrodeposited Fe-Ni film is often companied with poor surface quality and thermal expansion. To get proper film for masks making, experiments of electroforming Fe–Ni were performed with different ultrasonic powers and current densities. Results show that Fe-Ni film with smooth surface could be electrodeposited at high current density due to the reducing of internal stress of film by ultrasonic power. The iron content, grain size, micro-hardness and Young's modulus of film all present an upward trend with ultrasonic power increases from 13 W to 93 W, and then a downward trend due to the intensively transient cavitation caused by higher ultrasonic power 120 W. With the ultrasonic power of 93 W and current density of 1 A/dm2, a good surface quality of Fe-Ni films with 60.07 wt.% iron content, microhardness 351 HV, Young's modulus 167.5 GPa and CTE 3.38 × 10−6/℃ can be electrodeposited. [ABSTRACT FROM AUTHOR]