超高分子量聚乙烯与钢的冲蚀磨损研究

用气流喷砂型冲蚀试验装置对超高分子量聚乙烯（Ｕｌｔｒａ Ｈｉｇｈ Ｍｏｌｅｕｌａｒ Ｗｅｉｇｈｔ Ｐｏｌｙｅｔｈｙｌｅｎｅ,ＵＨＭＷＰＥ）和４５＃钢的冲蚀磨损性能进行进行了比较,考察了冲蚀粒子（煤粉,二氧化硅）的入射角,冲蚀时间等对超高分子量聚乙烯和４５＃钢冲蚀磨损的影响,通过扫描电子显微镜对超高分子量聚乙烯和４５＃钢冲蚀磨损表面形貌的观察,并对超高分子量聚乙烯和４５＃钢冲蚀磨损机理进行了初步探讨。     

省煤器管材料热冲蚀磨损的研究

利用自制热冲蚀磨损强化模拟试验装置,对制造省煤器管的20钢进行了热冲蚀磨损试验研究。结果表明:最大冲蚀率出现在20°攻角,而且材料的冲蚀率随气流速度增大,气流温度升高和气流中磨粒密度的增大而增加。扫描电镜观察表明,20钢的冲浊机制包括切削,犁削和冲击坑,其中低攻角时以前两者为主,高攻角时以后者为主。     

新疆岩蜥三元耦合耐冲蚀磨损特性及其仿生试验

选取新疆岩蜥为典型动物,以形态、结构、材料作为因素设计仿生耦合试样,通过喷砂试验检验耦合试样表面的冲蚀磨损特性。喷砂试验选用粒径为1000μm的Al2O3颗粒为磨料,对LY12硬铝合金与45#钢为基底的仿生耦合试样进行试验。结果表明,在冲蚀时间为180 s,入射角为30°,入射距离为200 mm,空气压力为0.4 MPa条件下,耦合试样耐冲蚀磨损性能较对照试样提高18.7%。耦合试样特征因子最优组合为以LY12硬铝合金为基底材料,非光滑单元形态的形状为圆形凹坑、直径为3 mm,单元间距为6 mm的规则分布,表面涂层(Al2O3+13%TiO2)厚度为100μm。     

Experimental studies on the erosion rate of different heat treated carbon steel economiser tubes of power boilers by fly ash particles

The experimental investigations on the effect of the fly ash particle size,velocity,impingement angle,and feed rate were done with an emphasis on the effect of erosion on annealed SA 210 GrA1(A) and normalized SA 210 GrA1(N) carbon steel economizer-tube materials.Erosion rates were evaluated with different impingement angles ranging from 15° to 90°,at four different velocities of 32.5,35,37.5,and 40 m/s,and at four different feed rates of fly ash particles of 2,4,6 and 8 g/min.The erodent used was fly ash p...     

离心机过流件常用材料的冲蚀磨损研究

利用喷砂机对离心机过流件常用的Q235A,Cr12Mov,ZG310-570和Q345A 进行冲蚀磨损试验,探讨它们的冲蚀磨损特性。结果表明：材料的硬度越高,其质量损失率越低,抗冲蚀磨损性能越强,4种材料的抗冲蚀磨损性能由高到低的顺序依次是Q345A,ZG310-570,Cr12Mov,Q235A;随着冲蚀角度的增大,质量损失率呈现先增大后减小的变化趋势,其中冲蚀角为30°时的质量损失率最大;在小角度冲蚀下,材料的磨损机理主要表现为微观切削,而大角度冲蚀下的磨损机理则主要表现为反复塑性变形导致的疲劳断裂。     

WC—Co硬质合金冲蚀磨损行为及机理研究

本文对两种WC—Co硬质合金的耐冲蚀性进行了考察,二者均呈现脆性材料冲蚀特点。其组成相的晶粒尺寸、硬度、百分含量与形貌对材料的冲蚀行为有巨大影响,在高温下尤为明显。材料的耐磨性随磨料硬度增加而降低。超细晶粒硬质合金具有更佳的耐磨性,但其磨蚀机理与商用硬质合金相似。软磨粒冲蚀引起软的Co相粘接剂浸蚀,导致WC相脱落。硬磨料冲蚀时,材料的转移主要是由于低角度时的切削和犁耕,高角度时的疲劳断裂组成,二者均伴有大面积的塑性变形。     

颗粒属性对输气管道渐缩管冲蚀磨损的仿真预测

在输气管道中，气固两相流对管道内壁造成冲蚀磨损，渐缩管中冲蚀磨损情况尤为严重。利用计算流体动力学相关知识，通过CFD仿真软件建立模型，运用流固双向耦合方程，采用标准k⁃ε模型和DPM模型进行分析。探究入口流速、固体颗粒粒径以及颗粒质量流率对渐缩管冲蚀磨损现象的影响，预测渐缩管中易发生冲蚀磨损的位置以及天然气的最佳流速。结果表明，当入口流速从5 m/s增大到25 m/s时，渐缩管最大冲蚀速率先增加后减小再增加；当入口流速为15 m/s时，冲蚀速率降至最小，为1.76×10－6 kg/（m2•s）；当颗粒粒径从0.5 mm增大到4.5 mm时，最大冲蚀速率先由4.23×10－6 kg/（m2•s）增加至7.56×10－6 kg/（m2•s），而后又逐渐减小至2.68×10－6 kg/（m2•s）；在入口流速为15 m/s的情况下，当颗粒质量流率从0.1 kg/s增大到0.6 kg/s时，最大冲蚀速率从1.76×10－6 kg/（m2•s）增加至1.00×10－5 kg/（m2•s）。渐缩管冲蚀磨损区域主要位于渐缩管喉部下壁面、距离喉部2D区域的收缩管段下壁面及2D区域以外的收缩管段上壁面，并且上壁面冲蚀磨损区域近似呈“U”型对称分布。在输气过程中，气体流经渐缩管的最佳入口流速应为15 m/s。为预防冲蚀磨损，颗粒粒径不宜过小，质量流率需控制在合理范围内。     

20g钢的冲蚀磨损性能的研究

采用气流喷砂型实验机,试验研究20g钢的冲蚀磨损性能。结果表明,20g钢是典型的金属塑性材料,其耐冲蚀磨损性能比较差。其冲蚀率峰值出现在30°附近(在本实验条件),其冲蚀磨损机理在攻角小于30°之前以切削模型为主,在攻角大于30°之后以局部塑性变形模型为主。其冲蚀磨损没有明显的孕育期,直接进入了持续期,冲蚀失重随冲击时间的增加而增加。冲击速度对20g钢的冲蚀磨损有很大的影响,其冲击速度与冲蚀率成指数关系,在本实验条件下,其指数为2.23。表明在高速时,20g钢的冲蚀磨损严重。     

Particle erosion of infrared materials

Erosion test of some infrared (IR) optical crystals (Ge,ZnS,MgF2,and quartz) was conducted with a number of different erodents (glass bead,and angular SiC,SiO2,Al2O3 by a homemade gas-blasting erosion tester.The influence of impact angle,impact velocity,erodent,and erosion time on the erosion rate and the effect of erosion on their IR transmittance were studied.The damaged surface morphology was characterized by scanning electron microscopy,and the erosion mechanism was explored.All of the materials show the maximum in wear versus impact angle at 90°,confirming their brittle failure behavior.It is found that the erosion rate is dependent on the erodent velocity by a power law,and it is highly correlated to the hardness of the erodent.The erosion rate-time curves do not show an incubation state,but an accelerated erosion period followed a maximum erosion (steady state).The decrease of IR transmittance is direct proportion to the erosion rate.Although the material loss occurs primarily by brittle process,ductile behavior is clearly an important feature,especially for MgF2 and ZnS.     

四墙切圆锅炉水冷壁颗粒冲击特性数值模拟

为深入了解水冷壁壁面的颗粒冲击特性,使用AnsysFluent对660 MW超临界锅炉的燃烧过程进行数值模拟,通过Fluent内冲蚀磨损模型得出燃烧器区域壁面的颗粒质量冲击量;利用Fluent软件的Sample功能输出壁面颗粒数据,将点数据导入Excel处理,得到冲击燃烧器区壁面的颗粒最高速度及颗粒速度值的分布情况. 结果表明:燃烧器喷口对侧区域的壁面冲击量最大值为6 kg·m^-2·s,冲击燃烧器区壁面的颗粒最高速度可超过30 m·s^-1,其占比不足冲击总颗粒量的0.3%,20~25 m·s^-1的冲击颗粒占比接近10%,颗粒速度的主体为5 ~ 20 m·s^-1. 壁面颗粒冲击量及颗粒速度模拟结果表明,在后墙第二组燃烧器壁面存在着6 kg·m^-2·s的高颗粒冲击量及25 ~ 29 m·s^-1的高颗粒冲击速度同时作用的区域,易发生严重磨损.     

风沙环境下钢结构涂层的冲蚀摩擦学性能

针对内蒙古中西部地区钢结构体系表面涂层长期遭受风沙环境冲蚀的这一现状,采用气流挟沙喷射法,模拟风沙对钢结构涂层的冲蚀.研究了风沙冲蚀力学参数对钢结构涂层冲蚀率的影响;探讨了涂层冲蚀损伤的摩擦学机理;分析了钢结构涂层的冲击摩擦因数变化规律.结果表明:涂层的冲蚀率均随着冲蚀速度呈指数增长,速度指数n为2.39~2.43;在45°时涂层的冲蚀率最大,90°时涂层的冲蚀率最小,低冲角时的冲蚀率大于高冲角时;涂层的摩擦因数处于0.37~0.42,涂层磨损的Taber指数为81.9×10-3mg/r,涂层的耐磨性较差.涂层损伤的摩擦学机理是:低冲角时的微切削作用或高冲角时的挤压凿削作用造成涂层的损伤占主导,涂层表面微裂纹扩展交叉,以致断裂剥落,造成的损伤次之;涂层冲击摩擦因数离散性较大,且随角度增长呈降低趋势;冲击摩擦因数与冲蚀率随角度的变化并不一致.     

低速冲击下C型冷弯薄壁钢构件动力响应分析

为了研究C型冷弯薄壁钢构件在横向冲击荷载作用下的动力性能,本文选用两组共12个冷弯薄壁槽钢梁构件进行冲击试验,并将试验构件的变形模式和试验测得的位移极值与ANSYS/LS–DYNA有限元模拟所得的结果进行对比分析,结果表明:两者的构件变形模式相似,位移极值差值均在8.0％以内,表明ANSYS/LS–DYNA有限元模型能...     

低角冲蚀磨损机理的研究

作者通过扫描电镜观察、磨屑分析、磨损面次表层硬度分析、增量冲蚀磨损法以及冲蚀磨损的准动态观察等多种分析方法对几种钢和纯金属在低角下的冲蚀磨损机理进行了深入的研究。结果发现:对于延性比较大的金属材料,磨损初期主要是发生塑性变形,形成压坑与变形唇,继之,度形唇被反复地前挤后压,终以小块剥落而磨损。延性比较小的材料则更多地产生微切削磨损。     

High temperature behaviors of high velocity arc sprayed Fe-Al/Cr3C2 composite coatings

Fe-Al/Cr3C2 composite coatings were manufactured using high velocity arc spraying （HVAS） technology. The high temperature erosion, wear and corrosion resistance of the coatings were investigated. The coating properties such as bonding strength, porosity, hardness as well as microstructures were characterized. The results show that the coatings have relatively high heat tremble bond strength, hardness, and typical layer-shaped coatings＇ microstructures. With the rise of temperature, the coating erosion resistance increases too; the impingement angel does effects on erosion properties, and the erosion mechanism changes from ductile to brittle behaviors at 450℃. The coatings have good room temperature wear resistance and relatively good high temperature resistance. The wear mechanism of the coatings is peeling wear behavior. The coatings have excellent high temperature corrosion resistance because of the produce of oxides during corrosion.     

浓相气力输送中变径管道优化设计方法的研究

针对浓相气力输送中由于气流速度过高所引起的管道磨损和物料品质降级等问题，提出了一种变径管道系统设计方法。基于变径管道与同径管道压力损失相同的变径原理，推导了变径管道设计参数的计算公式，给出了变径管道的弗劳德数法和临界速度法两种变径定位方法及管段结构参数的选择依据，并讨论了变径弯管渐扩渐缩和垂直下流管渐缩的特殊变径原理。实例计算结果表明，采用变径管道设计方法可以将管道终端的气流速度由26.40 m/s降低到7.28 m/s，系统的输送压力由0.65 MPa降低到0.36 MPa，系统的输送性能提高，能耗降低。     

Corrosive Wear Mechanism of Stainless Steels

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Composite rock-breaking of high-pressure CO2 jet & polycrystalline-diamond-compact(PDC) cutter using a coupled SPH/FEM modelOA

CO₂ drilling is a promising underbalance drilling technology with great advantages, such as lower cutting force, intense cooling and excellent lubrication. However, in the underbalance drilling, the mechanism of the coupling CO₂ jet and polycrystalline-diamond-compact(PDC) cutter are still unclear. Whereby, we established a coupled smoothed particle hydrodynamics/finite element method(SPH/FEM) model to simulate the composite rock-breaking of high-pressure CO₂ jet...     

A numerical simulation study on mechanical behaviour of coal with bedding planes under coupled static and dynamic load

To investigate the bedding influence on coal mechanical behaviour in underground environments such as coal or rock burst, simulations of dynamic SHPB tests of pre-stressed coal specimens with different bedding angles were carried out using a particle flow code 2-dimensional(PFC2D). Three impact velocities of 4, 8 and 12 m/s were selected to study dynamic behaviours of coal containing bedding planes under different dynamic loads. The simulation results showed that the existence of bedding planes leads to the degradation of the mechanical properties and their weakening effect significantly depends on the angle h between the bedding planes and load direction. With h increaseing from 0° to 90°, the strength first decreased and subsequently increased and specimens became most vulnerable when h was 30° or 45°.Five failure modes were observed in the specimens in the context of macro-cracks. Furthermore, energy characteristics combined with ultimate failure patterns revealed that maximum accumulated energy and failure intensity have a positive relation with the strength of specimen. When bedding planes were parallel or perpendicular to loading direction, specimens absorbed more energy and experienced more violent failure with increased number of cracks. In contrast, bedding planes with h of 30° or 45° reduced the specimens' ability of storing strain energy to the lowest with fewer cracks observed after failure.     

Gas-solid erosion on bionic configuration surface

A three levels orthogonal table-L9(34) was used,namely,impact angle,rotating speed,erodent size,and surface configuration were considered.The three bionic surface configurations are pit,groove,and ring.The experimental results indicate the experiment factors affecting erosive rate are,in their sequence of contribution,erodent size,impact angle,configuration,and rotating speed;the erosive rate increased with increase in rotating speed,erodent size;the erosion resistance of the sample with ring structure is higher than that of the other two samples.Based on this result,regression orthogonal experiment was carried out to select the optimal erosion resistance condition with respect to the ring bionic surface configuration.Regression equations between erosive rate and experimental factors of ring surface configurations were obtained.     

Erosion-Corrosion Behaviors of High Velocity Arc Sprayed Fe-Al/Cr3 C2 Coating

1 IntroductionArc Spraying (AS) is a technique that utilizes anelectric arc as the heat source to melt wires into droplets ,which are subsequentlysprayed ontosubstrates bytheflowof compressed air . High Velocity Arc Spraying (HVAS)technology was developed on the basis of AS. Aspecialtube designed according to the principle of aerodynamicswas mounted at the exit of compressed air .Thenthe hightemperature fuel air or compressed air was accelerated bythe tube .Hence ,a higher velocityand be…