Preparation and Characterization of Ni60-Cr<Subscript>3</Subscript>C<Subscript>2</Subscript>-WC/TiC Plasma Welding Surfacing Layer

Using plasma build-up welding technology, Ni60, WC, Cr₃C₂, and TiC composite powders were clad on the surface of the substrate in a certain proportion according to the metallurgical bonding method to increase the bond strength between the coating and the substrate. Scanning electron microscopy and energy dispersive spectroscopy were used to observe the microstructure of the surfacing layer and the chemical composition of the sample. The hardness and wear resistance of the surfacing layer were tested and analyzed by the HV-1000 hardness tester and the impact wear device. The results showed that in the microstructure, fishbone, spider-web, and floral-like structures appeared in the surfacing layer. When the micro-hardness was tested, the depth of the indentation reflected the hardness of the surfacing layer. When analyzing wear resistance, the amount of wear increases with time.     

新型超低NOx燃气燃烧器设计及数值模拟

国家"煤改气"政策实施以来,燃气锅炉的应用日渐广泛,开发和设计新型超低NO_x燃气燃烧器具有重要意义。介绍了烟气再循环、燃料分级燃烧以及旋流空气分级等低NO_x燃气燃烧技术,分析了新型燃气燃烧器燃烧过程中NO_x的生成机理和控制因素。通过数值方法,对一台新型燃气燃烧器的燃烧过程进行模拟,得到流场、温度场和NO_x浓度场等,发现燃烧火焰均匀分散地充满整个炉膛,没有局部高温区域,从而避免了NO_x的大量生成。根据计算,炉膛出口NO_x排放浓度为66mg/m~3,符合新型燃烧器超低NO_x排放的设计目标。     

应用层次分析法确定矿井顶板涌水影响因素的权值

在矿井顶板涌水等级评价中,如何确定各主要影响因素的权重是一个很重要的问题。应用层次分析法(AHP),对影响顶板涌水量的主要因素进行加权,获得了比较实际的权重结果,为矿井顶板涌水等级评价提供了更准确的依据。