Corrosion resistance of CrN film deposited by high-power impulse magnetron sputtering on SS304 in a simulated environment for proton exchange membrane fuel cells

Insufficient corrosion resistance and conductivity are two major problems hindering the wide application of stainless steel (SS) bipolar plates in proton exchange membrane fuel cells. This study explores the use of CrN monolayer and multilayer films to improve the performance of SS304 bipolar plates, which are realized by high-power impulse magnetron sputtering with single pulse width or alternating pulse width. The effect of pulse width on the film structure and composition was characterized by various characterization techniques. Furthermore, corrosion and interfacial contact resistance (ICR) test results show that monolayer CrN film using a single long pulse of 40 μs has the lowest corrosion current density of 0.08 μA/cm² (0.6 V vs. Ag/AgCl) and ICR of 3.15 mΩ cm² in all coated samples. As the pulse width increases, vacancy-like defects in film decrease and the density increases, which is attribute to high bombardment flux and high average power of long pulse during deposition.     

Piezoelectric properties of [001]-textured high-power PMnN-PZT piezoceramics sintered at a low temperature

The 1.0 mol% CuO-added 0.14Pb(Mn1/3Nb2/3)O₃-0.86Pb(Zr_0.55Ti_0.45)O₃ (CPMnN-PZT) piezoceramics were synthesized at low temperatures (≤ 950 °C) by the columbite method to remove the pyrochlore phase. It exhibited a high Q_m of 3016 and a high T_C of 309 °C. However, it showed small d₃₃ and k_p values of 143 pC/N and 0.43, respectively. The CPMnN-PZT piezoceramic was textured along the [001] direction using BaTiO₃ (BT) templates to enhance its soft piezoelectric properties. The [001]-textured CPMnN-PZT + y vol% BT piezoceramics (1.0 ≤ y ≤ 5.0) were densified at a low temperature of 950 °C with a high Lotgering factor (≥ 92%). The textured sample (y = 1.0) showed a high Q_m of 1400 with increased d₃₃ and k_p values of 278 pC/N and 0.58, respectively, and its piezoelectricity showed excellent temperature stability up to 225 °C. Therefore, the textured CPMnN-PZT sample can be used for developing high-power piezoelectric devices.     

延长16V240ZB大功率柴油机喷油嘴使用寿命的途径

本文针对工况极为苛刻的１６Ｖ２４０ＺＢ柴油机喷油嘴（简称２４０喷油嘴）在使用过程中所出现的质量问题，提出了从结构设计、材料、热处理、制造精度等方面来提高２４０喷油嘴的可靠性和延长其使用寿命．实践证明，这一综合改进措施效果良好。     

世界大功率柴油机发展应用综述

本文通过对世界著名柴油机厂家的业绩统计，综述了船用和陆用电站大功率柴油机的使用分布情况，并分析了大功率柴油机的发展趋势。