达克曲克电站水轮机过流部件抗磨蚀防护技术的分析及应用

达克曲克电站属于多泥沙河流水电站,由于水轮机过流部件遭泥沙磨损损坏严重,降低了机组能量性能,并引起机组及厂房发生振动等重大安全隐患。为此,针对机组过流部件泥沙磨蚀严重问题,分析了磨蚀产生的原因,提出采用不同的防护方案对水轮机不同的磨蚀区域进行处理。经机组运行一个汛期后发现,该抗磨蚀修复方案有效缓解了机组的磨损和汽蚀问题,达到了降低电站维修成本、节能降耗的目的。     

±800 kV换流站逆止阀扭转弹簧断裂原因分析

某±800 kV换流站换流阀内冷水系统主循环泵出口逆止阀内部扭转弹簧的弹簧臂发生断裂, 采用断口宏观检查、化学成分分析、硬度检测、扫描电镜分析、应力计算等手段, 对扭转弹簧断裂失效原因进行了分析。结果表明, 逆止阀内扭转弹簧失效的主要原因是疲劳断裂和摩擦磨损。扭转弹簧和逆止阀存在的设计缺陷也加速了弹簧失效: 在动负荷工作状态下扭转弹簧的局部最大弯曲应力达到许用弯曲应力, 容易引发弹簧发生疲劳断裂;逆止阀结构设计不合理, 加速弹簧臂摩擦磨损。     

机械结构设计的思路及抗磨降噪措施探讨

机械结构设计主要是对既定功能的零部件进行材料、形状、尺寸、公差和布局等方面的确定,同时考虑加工工艺、强度、刚度、精度以及与其他零部件之间的关系等问题。文章首先阐述了机械结构设计的总体思路以及设计方法,然后对机械结构设计中常见的抗磨降噪措施进行分析,为促进机械结构设计水平的提升的提供参考。     

Compressive strength and abrasion resistance of concrete containing SiO_2 and CuO nanoparticles in different curing media

In the present study,abrasion resistance and compressive strength of concrete specimens containing SiO2 and CuO nanoparticles in different curing media have been investigated.Portland cement was partially replaced by up to 2.0 wt%of SiO2 and CuO nanoparticles and the mechanical properties of the produced specimens were measured.Increasing the nanoparticles content was found to increase the abrasion resistance of the specimens cured in water and saturated limewater,while this condition was not observed for c...     

Comparative analysis of mechanical properties of size films

The advent of very high speed shuttleless looms has increased the importance of sizing. Starch has been the most popular and economic size material. Synthetic binders are also being blended with starch to improve weaving loom efficiency. Some synthetic size materials have got restrictions in use mainly because of ecological reasons. In the recent years, many modifications have come up in the starch as a sizing agent. Different modifications give different properties, which can be suited for particular application. In the present study, a comparative analysis of different varieties of natural starch, modified starch and synthetic size materials have been carried out for their cohesion power, adhesion power, abrasion resistance and bending rigidity. Comparison is made between various varieties and also among different blends to see the effect of blending on different mechanical properties of size film. The effect of lubricant on properties of size film is also examined. In general, it is observed that paste characteristics and film properties of synthetic and modified starch are better than the natural starch.     

Al_2O_3和ZrO_2基耐磨复合材料

采用热压和微电弧氧化工艺制得了含ZrO2 的氧化铝基耐磨复合材料     

喷气织机异形筘磨损分析及维护

分析了喷气织机异形筘磨损的主要原因及影响因素，提出了异形筘维修的方法及减少磨损的有效途径，不失为降低生产成本的有效措施。     

南1-斜1井套管锻铣技术

介绍了国内２４４．５ｍｍ套管锻铣位置最深的南１－斜１井套管锻铣及侧钻情况。从６个方面分析了深部井段锻铣施工难点。提出了两种锻铣刀具的选择与使用技术措施。探讨了套管锻铣位置的确定及锻铣效果的判断等问题。     

Real-time confocal imaging, during active air abrasion – substrate cutting

Air abrasion cutting, using particulates accelerated in a controlled compressed gas stream, is currently being re-evaluated as a precision tissue removal technique for dental cavity preparation. The minimal vibrations and heat generated during cutting commend the technique for use in the shaping of fragile or brittle materials that are vulnerable to vibrations and thermal stresses.
Traditional air abrasion studies have relied solely upon post-procedure imaging, and cutting process details have been inferred from the nature of the residual surface. In this paper, however, a real-time confocal microscopic imaging method is described, which for the first time has allowed prior target structure characterization with subsequent imaging of cutting interactions and substrate failure patterns. Using internally focusing long working distance Hill objective lenses, focusing deep to a protective microscope slide and adhesive interfaces, unhindered remote image sampling within the bulk of specimens such as tooth tissue, acrylic and brittle ceramics was possible.
Moreover, areas of active cutting and inactive regions were identified within air abraded cavities during their creation. The characteristics of the finished cut surfaces were demonstrated and confirmed the findings of previous SEM studies. The method allowed direct control over all the known variables influencing cutting with particulate streams.     

Deposition and properties of high-velocity-oxygen-fuel and plasma-sprayed Mo-Mo2C composite coatings

Molybdenum thermal-spray coatings, dispersion strengthened by molybdenum oxides and molybdenum carbides, play an important role in industrial tribological applications. Traditionally, they have been prepared by plasma and wire flame spraying. High porosity and lower cohesion strength limit their application in situations where both galling and abrasion wear is involved. In this study, high-velocity-oxygen-fuel (HVOF) deposition of molybdenum and molybdenum carbide coatings was attempted. Deposition was achieved for all powders used. Composition, microstructure, mechanical, and wear properties of the HVOF synthesized coatings were evaluated and compared with plasma-sprayed counterparts. The HVOF coatings possessed a very good abrasion resistance, whereas plasma deposits performed better in dry sliding tests. Measurements showed a close relationship between the coating surface hardness and its abrasion resistance. Results also suggested correlation between molybdenum carbide distribution in the molybdenum matrix and the sliding friction response of Mo-Mo₂C coatings.