40万t矿砂船CO_2气体保护焊与埋弧自动焊混合焊接工艺方法

针对40万t VLOC船体甲板所采用的厚达49 mm的EH36钢材,考虑其高应力和高疲劳强度的特点,采用CO_2气体保护焊打底、两道填充和埋弧自动焊填充、盖面的混合高效焊接工艺技术,对焊缝打底、填充、盖面焊接中所产生的焊接缺陷进行工艺优化,通过打底焊缝厚度的控制、埋弧自动焊填充、盖面操作技术的使用及采取相应的焊接工艺措施,最大限度避免焊接缺陷产生,焊接质量明显提升,生产效率有较大的提高。     

Study on Oxidation Activity of CuCeZrO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Doped with K for Diesel Engine Particles in NO/O<Subscript>2</Subscript>

CuCeZrO_x and KCuCeZrO_x catalysts were synthesized and coated on the blank diesel particulate filter (DPF) substrate and a particulate matter (PM) loading apparatus was used for soot loading. The catalytic performances of soot oxidation were evaluated by temperature programmed combustion (TPC) test and characterization tests were conducted to investigate the physicochemical properties of the catalysts. The reaction mechanism in the oxidation process was analyzed with diffuse reflectance infrared Fourier transform spectroscopy. The results demonstrated that CuCeZrO_x catalyst exhibited high activities of soot oxidation at low temperature and the best results have been attained with Cu_0.9Ce_0.05Zr_0.05O_x over which the maximum soot oxidation rate decreased to 410 °C. Characterization tests have shown that catalysts containing 90% Cu have uniformly distributed grains and small particle sizes, which provide excellent oxidation activity by providing more active sites and forming a good bond between the catalyst and the soot. The low-temperature oxidation activity of soot could be further optimized due to the excellent elevated NO’s conversion rate by partially substituting Cu with K. The maximum particle oxidation rate can be easily realized at such a low temperature as 347°C.