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Micro electroforming technology is widely used in fabrication of multilayer or moveable metal micro devices. The fabrication of these devices is usually suffered from high internal stress in micro-electroformed layers which seriously restricts the application and development of micro electroforming technology. Therefore, to control the internal stress is very important for improving the quality and performance of micro-electroformed layer. However, published studies on internal stress in the electroforming layer were mostly based on additive-free solution. According to additive solution, the effect of ultrasonic and current density on compressive stress occurring in the electroforming layer is investigated in this paper. The results indicate that the compressive stress keeps increasing with current density within range from 0.2 to 2 A/dm2. Meanwhile, the compressive stress in ultrasonic solution decreases by 73.4 MPa averagely comparing to that in ultrasonic-free solution, and the compressive stress also keeps decreasing with the ultrasonic power which gets the lowest value at 200W. Moreover, the mechanisms of additive-induced compressive stress and ultrasonic relieving compressive stress are discussed. This research work will complement the ultrasonic-stress reduction theory and may contribute to the development of micro electroforming technology.

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Ramie fiber‐reinforced polymer (RFRP) composites are widely used in various fields owing to their environmental friendliness and cost efficiency. To understand the influence of different resin matrices on the mechanical properties and durability of RFRP composites under the same conditions and obtain better performance, ramie fiber‐reinforced phenolic resin (RFRPR) composites and ramie fiber‐reinforced unsaturated polyester (RFRUP) composites produced through compression molding were studied under hydrothermal conditions of 60°C with 50%, 85%, and 98% relative humidity for 3 months. The water absorption, tensile, flexural, and short‐beam shear properties were studied. The RFRPR composite had better flexural strength and short‐beam strength than the RFRUP composite. The saturated water absorption, water molecule diffusion coefficient, and retention rate of the RFRUP composite were higher than those of the RFRPR composite owing to the difference in the interfacial adhesion properties. The erosion of water molecules led to serious deterioration in the interfacial bonding performance of the RFRPR composite. It was found that the greater the humidity, the greater was the degree of interfacial degradation. This study lays the foundation for the further promotion and application of RFRP composites.