高聚物磨损研究的近况

随着高分子材料的应用日益广泛，其磨损现象越来越受到重视。本文综述了近年来国内外学者在高分子材料磨损方面的研究工作，着重阐述了滑动磨损、磨粒磨损、冲蚀磨损的研究进展。     

高聚物磨损研究的近况

随着高分子材料的应用日益广泛，其磨损现象越来越受到重视。本文综述了近年来国内外学者在高分子材料磨损方面的研究工作。着重阐述了滑动磨损，磨料磨损，冲蚀磨损的研究进展。     

电沉积镍合金的冲蚀-腐蚀磨损研究

采用MSH型腐蚀磨损试验机研究了电沉积纯Ni、Ni-P非晶合金、Ni-W-P非晶合金的冲蚀-腐蚀磨损行为,并结合电化学测量系统研究了上述材料冲蚀与腐蚀之间相互促进机理。结合XRD分析了冲蚀前后电沉积镍合金的相变行为。结果表明：冲蚀-腐蚀磨损试验前后,电沉积镍合金镀层的硬度都增加;Ni-P非晶合金受到冲击后,镀层明显的发生了由非晶向微晶的转变;镍合金在含盐砂浆中的腐蚀性能随着工况的不同而不同,试样在含盐砂浆中的冲击速度由0增加到3.14ms-1时,三种材料的腐蚀速率都减小,之后随着冲击速度的增大,试样腐蚀速度增加;镍及镍合金材料的冲蚀-腐蚀磨损失重都以冲蚀失重为主,试验条件下冲蚀与腐蚀的交互作用最高能使材料的冲蚀-腐蚀磨损失重增加42%。     

不锈钢材料高温冲蚀磨损性能与机理

为弄清磨粒对工业设备常用材料304不锈钢的冲蚀磨损情况,采用自行设计的气流喷砂式高温磨损试验机,对其进行不同温度下的冲蚀磨损。分析了温度、冲蚀角度、磨粒粒径以及磨粒速度对其冲蚀磨损率的影响,并分析了其冲蚀磨损机理。结果表明:温度对冲蚀磨损率有显著影响,304不锈钢表面氧化膜在400℃时抑制了磨粒的冲蚀,高温下金属塑性升高降低了高角度下磨料的冲击破碎作用,但低角度下抗微切削能力下降;冲蚀磨损率随磨粒粒径的减小先增大后减小再增大,随磨粒速度增大而增大;磨粒对试样表面的低角度微切削和高角度冲击破碎作用是材料冲蚀磨损的主要机理,304不锈钢表面的冲蚀磨损主要来源于微切削作用。     

金属及陶瓷材料冲蚀研究的进展

固体颗粒冲击材料表面造成的冲蚀磨损，受入射粒子及靶材性能等多种因素影响；本文综述了金属材料的微切削、挤压锻造、变形磨损及脱层冲蚀磨损模型和陶瓷材料的弹塑性、准静态及晶粒弹射等冲蚀模型，以及由于入射粒子碎裂引起的二次冲蚀模型，并讨论了冲蚀的影响因素。     

超高分子量聚乙烯的剖蚀磨损

用气流喷砂型冲蚀试验装置测试了超高分子量聚乙烯（ＵｌｔｒａＨｉｇｈＭｏｌｅｃｕｌａｒＷｅｉｇｈｔＰｏｌｙｅｔｈｙｌｅｎｅ）的冲蚀磨损性能，考察了冲蚀粒子的入射角，速度，粒子的硬度对冲蚀磨损的影响，用扫描电子显微镜观察冲蚀磨损表面形貌，指出：在高角冲蚀时，磨损机理主要为塑性变形和显微裂纹；在低角冲蚀时，磨损机理主要为显微镜切削和显微犁耕冲蚀磨损机理与冲蚀粒子有关。     

超高分子量聚乙烯的冲蚀磨损

用气流喷砂到冲依试验装置测试了超高分子量聚乙烯（UltraHighMolecularWeightPolyethylen）的冲蚀磨损佳能．考察了冲蚀粒子的入射角、速度、粒子的硬度对冲蚀磨损的影响．用扫描电子显微镜观察冲蚀后报表面形统指出：在高角冲蚀时，摩根机理主要为塑性变形和显微裂纹；在低角冲蚀时，磨损机理主要为显微切削和显微犁耕．冲蚀磨损机理与冲蚀粒子有关．     

水力压裂工况高压管汇冲蚀磨损研究进展及展望

水力压裂施工中,高压管汇内壁承受携砂液中高流速、高强度支撑剂的冲蚀磨损作用,易发生损伤失效。通过总结现有的冲蚀理论和冲蚀试验装置,系统介绍了国内外对高压管汇材料冲蚀磨损问题的研究成果,对比分析了旋转式、喷射式和管流式试验装置对水力压裂工况下高压管汇冲蚀磨损研究的适用性,着重分析了喷射式冲蚀磨损试验中各试验参数对高压管汇冲蚀速率的影响规律;最后指出了当前水力压裂工况下高压管汇冲蚀磨损研究中存在的问题及未来的研究方向。     

Al2O3颗粒增强共晶成分铝锰基复合材料冲蚀磨损性能研究

通过对Al2O3颗粒增强Al-2.06%Mn复合材料和Al-2.15%Mn合金在不同磨粒粒径、不同冲蚀速度的冲蚀磨损试验,探索了材料的冲蚀失效规律及其微观破坏机制。结果表明,两种材料在7m/s冲蚀速度下的冲蚀磨损失重率是在3.5m/s冲刷速度下的2～3倍;两种材料的冲蚀磨损失重率随着磨粒粒径的增大先增大后减小,磨粒粒径分布在0.053～0.106mm时两种材料的失重率出现极大值,Al2O3颗粒增强Al-2.06%Mn复合材料的抗冲蚀磨损性能优于Al-2.15%Mn合金。     

纳米SiO_2/沥青改性环氧树脂的抗冲蚀磨损性能

为了降低强风沙流区混凝土的冲蚀磨损,常采用环氧树脂材料对其进行防护,但环氧树脂材料存在交联度高、脆性较大等缺点。为此,采用纳米Si O2和沥青对环氧树脂进行了改性,研究了改性环氧树脂的力学性能和冲蚀磨损性能,并分析了其冲蚀磨损机理。结果表明:纳米Si O2和沥青共同改性环氧树脂不仅提高了环氧树脂的拉伸强度,同时改善了环氧树脂的冲击韧性;改性环氧树脂材料表现出半塑性材料的冲蚀特征,最大冲蚀率出现在45°冲蚀角,冲蚀率与冲蚀速率呈指数关系,速率指数为2.65~3.25;1%纳米Si O2和10%沥青协同改性的环氧树脂表现出了良好的冲蚀抗力,是强风沙流环境下混凝土结构冲蚀磨损防护的可选材料。     

材料表面抗空蚀涂层的研究进展

空蚀现象广泛存在于海洋平台、船舶机械和能源发电等领域。这种腐蚀现象不仅造成了巨大的经济损失,也成为相关从业人员的安全隐患。本文概述了抗空蚀涂层材料技术的研究进展,重点介绍了抗空蚀金属涂层技术和抗空蚀聚合物涂层技术。最后对目前抗空蚀材料存在的问题及未来发展进行了展望。     

Sialon陶瓷的冲蚀磨损及磨粒磨损行为

以ＳｉＣ作为磨粒较全面地研究了Ｓｉａｌｏｎ陶瓷的磨损性能：冲蚀磨损和磨粒磨损性能．Ｓｉａｌｏｎ陶瓷在冲蚀磨损实验中表现出了脆性冲蚀的特征,在高角冲蚀下,冲蚀磨损率随着冲蚀角度的增大而迅速增加,并在冲蚀角为９０°附近达到最大．ＳＥＭ分析表明Ｓｉａｌｏｎ陶瓷的冲蚀磨损机理主要是显微切削和表面颗粒拔出脱落．在Ｓｉａｌｏｎ陶瓷的磨粒磨损实验中,较高载荷作用下,磨损量与时间之间有指数变化关系;较低载荷作用下,磨损初期有一个短暂的磨损量基本不变的孕育阶段,随后进入快磨损阶段,本文对该孕育现象进行了探讨．对磨损表面的ＳＥＭ分析发现;Ｓｉａｌｏｎ陶瓷的磨粒磨损机理主要是犁耕和表面断裂脱落．     

Assessment of erosion wear in low specific speed Francis turbine due to particulate flow

The erosion wear of turbine components reduces the turbine life and consequently decreases the efficiency or power generation. In the present work, the effect and cause of erosion wear in a high head Francis turbine are investigated through the measurements and numerical simulations on a prototype turbine. Localised erosion patterns are observed over the surface of the guide vane, runner, faceplate, and labyrinth seal due to existing particulate flows. Further, the physical interpretation of erosion wear mechanisms is studied through numerical simulations, and the eroded zones of different components are qualitatively validated with the actual site in-situ measurements. The erosion rate prediction of the turbine components is performed by employing a recently developed erosion model for CA6NM turbine material. The results show that the continuous interblade vortex with significant velocity and crossflow between the blade passages is found accountable for the severe erosion of the runner shroud. The dominating effect of flow instability at the off-design operation depicts higher erosion of turbine components. Moreover, the exponent value for the particle size is found to vary in the range of 1.16–1.30 for the material removal rate of turbine components.     

Effect of carbides on erosion resistance of 23-8-N steel

Microstructure is one of the most important parameters influencing erosion behaviour of materials. The role of carbides in the matrix is very complicated in controlling the erosion rate of the materials. Conflicting results have been reported in the literature about the effect of carbides on erosion resistance. Carbides are of great importance especially as obstacles against the penetration of erosive particles into the material surface. However, they are susceptible to cracking and causing matrix decohesion which may increase the overall erosion rate. In 23-8-N nitronic steel, carbides present in the form of bands are observed to accelerate the erosion rate. Coarse carbides cause depletion of carbon in the austenite matrix which adversely affects the strain hardening tendency thus causing deterioration in erosion resistance of the bulk material. The dissolution of carbides in the austenitic matrix after solution annealing is observed to improve the erosion resistance of 23-8-N nitronic steel.     

SiC陶瓷的冲蚀磨损耐磨性

研究了无压（ＰＬ），热压（ＨＰ）、热等静压（ＨＩＰ）烧结ＳｉＣ陶瓷的室温冲蚀磨损行为。热等静压ＳｉＣ陶瓷具有良好的综合力学性能和细致的组织结构，其冲蚀磨损耐磨性比无压的热压烧结ＳｉＣ陶瓷要好。     

Hybrid high-temperature fouling and erosion characteristics of gas-particle flow around heating tube via CFD-DEM

In this study, hybrid fouling and erosion of heating tube are presented via CFD-DEM. To analyze their characteristics, new high-temperature fouling and erosion sub-models, using a soft-sphere model considering the temperature-corrected material properties, are raised. The prediction of coupling morphologies is solved by clustered particles and dynamic mesh. The magnification factors of time are applied to the computation speedup for a long-time fouling and erosion. Results indicate that good agreements, of the critical adhesion velocity, high-temperature fouling and erosion on the heating tube, have been found between the experimental measurements and numerical predictions. As the inlet flow temperature goes up, the fouling amount increases, and oppositely the erosion amount decreases. As the surface temperature increases, both fouling and erosion amounts increase. As the particle size increase, the primary determinant of fouling varies from the impact efficiency to the impact efficiency and the critical adhesion velocity. Most innovative is to reveal the competition between the fouling and the erosion. In addition, reducing the surface temperature, as a way of temperature control, should be the priority to reduce fouling and erosion.     

Erosion wear response of ramie-epoxy composites using artificial neural network integrated with Taguchi technique

This paper aims on evaluating the erosion wear behavior of epoxy composites reinforced with ramie fibers. The possibility of reinforcing ramie fiber to improvise the wear resistance of epoxy is investigated in this study. Composites are fabricated by reinforcing multiple layers of woven ramie fiber mats into epoxy resin using conventional wet lay-up technique and erosion wear trials are conducted using solid particle erosion test setup. Taguchi analysis is done to assess the relative significance of each of the factors influencing the erosion rate using L₁₆ orthogonal array. The analysis reveals that the impact velocity followed by impingement angle are the most significant control factors affecting the erosion wear rate of ramie-epoxy composites. Steady state erosion analysis is done to ascertain the effect of each of the significant factors while keeping other factors fixed. Further, an analytical and predictive model based on the principle of neural computation is used to predict the rate of erosion wear of the composites and the obtained results are compared with the experimental outcomes. The worn morphologies of the eroded surfaces of the composites are studied and analyzed to identify possible mechanisms causing wear.     

Investigation on failure process and structural optimization of a high pressure letdown valve

High pressure letdown valve in direct coal liquefaction is used to adjust the flow rate of coal–oil slurry that enters into the downstream separator. Severe erosion–cavitation wear is found on the valve spool, seriously affecting the safety and reliability of unit. The majority of this paper investigates the failure process of valve spool and proposes a corresponding structural optimization via computational fluid dynamics (CFD) methodology. Three geometries of different failure states are selected as the computational domains in the numerical simulation. The Schneer–Sauer model, particle rebound-velocity model and erosion model are employed to calculate the cavitation phenomenon and erosion rates distribution. Experiments of flow rates and cavitation on valve model under different pressure drops are conducted to validate the accuracy of numerical approach. Results showed that the damage development of valve spool aggravates the erosion–cavitation wear. The maximum erosion rates are located on the top of spool head in all the three states. The erosion rates on spool arc surface are two orders of magnitude higher than that on parabolic surface. The decrease in radius of spool head reduces the intensities of erosion–cavitation wear. The numerical results are in agreement with actual failure morphologies of valve spool in different states.     

Approaches to enhance elevated temperature erosion resistance of Ni-base superalloys

Erosive wear is also known as impact wear. Several industrial components are degraded due to solid particle erosion at high temperatures. Solid particle erosion of metallic materials at high temperatures is influenced by the nature of interaction between erosion and oxidation. The main objective of the present work is to critically examine how strength and oxidation behaviour can be tailored to enhanced resistance to solid particle erosion of Ni-base superalloys at high temperatures. It is noted that alloys which form Al₂O₃ scale are likely to have good erosion resistance. This study examines methods of improving the erosion resistance by enhancing the elevated temperature mechanical properties. Methods for forming various scales and improving their adhesion characteristics are also elaborated.     

Erosion coupled dynamic mesh analysis for location of maximum erosion in 90-degree bends for gas-solid flows

The progressive change in the surface geometry of the component due to erosive wear affects the correct estimation of erosive wear performance and service life of the components handling particulate flows. The current study focuses on determining the change in the location of higher erosion on the bend surface during the pneumatic conveying of solids with continuous geometric modification due to erosive wear. Computational fluid dynamics (CFD) based erosion-coupled dynamic mesh methodology is adopted to simulate the time-dependent surface modification of the 90° bend geometry due to erosive wear. Available experimental data are used to validate the numerical results. Further, the erosion distribution and the location of the maximum erosion for different flow velocities, particle sizes, and bend radius ratios with the increase in solid throughput are investigated. It has been found that the modification in the bend geometry due to erosion influences the location of the maximum erosion. The increase in thickness loss due to erosion increases the variation in the location of the maximum erosion. Furthermore, an equation for predicting the location of maximum erosion of bend geometry is obtained based on the bend radius ratio and the thickness loss.