A novel and comprehensive evaluation index considering various processing parameters in additive manufacturing with four different scanning patterns was proposed. The relationship between the evaluation index and the performance of parts made by directed energy deposition was established and verified by experiments. The differences of thermal evolution between four scanning patterns were analysed. Comprehensive evaluation indices corresponding to different scanning patterns were calculated by integrating the contributions of various parameters, such as delamination, warping, porosity, heat accumulation, cooling rate, dendrite spacing, and deposition efficiency. The comprehensive evaluation indices off our scanning patterns were ranked in the following order (from lowest to highest): single-track zigzag, single-track, bi-direction, and spiral inward patterns. The performance of the single-track zigzag pattern was the best, and that of the spiral inward pattern was the worst. The single-track and bi-direction patterns showed intermediate performances under the same conditions. The closer the index is to zero, the better the performance. This index can be used for the quantitative evaluation of process quality and prediction of performance. It provides guidance for additive manufacturing process development and optimisation, reduces workload, and provides a new idea for quantitative performance evaluation and prediction of parts fabricated by additive manufacturing.

With the aim of preparing paper-based writing electronics, a kind of conductive pen was made with nano-silver ink as the conductive component and a rollerball pen as the writing implement. This was used to direct-write conductive patterns on Epson photo paper. In order to decrease the sintering temperature, pressure was introduced to enhance the driving forces for sintering. Compared with hot sintering without pressure, hot-pressure can effectively improve the conductivity of silver coatings, reduce the sintering time and thus improve productivity. Importantly, pressure can achieve a more uniform and denser microstructure, which increases the connection strength of the silver coating. At the optimum hot-pressure condition (sintering temperature 120 ° C/sintering pressure 25 MPa/sintering time 15 min), a typical measured resistivity value was 1.43 × 10−7 Ω m, nine greater than that of bulk silver. This heat treatment process is compatible with paper and does not cause any damage to the paper substrates. Even after several thousand bending cycles, the resistivity values of writing tracks by hot-pressure sintering stay almost the same (from 1.43 × 10−7 to 1.57 × 10−7 Ω m). The stability and flexibility of the writing circuits are good, which demonstrates the promising future of writing electronics.