激光熔敷钴合金涂层的抗空蚀和冲刷磨损性能

采用激光熔敷方法在20SiMn低合金钢表面制成了Co合金涂层，以两种目前水轮机转用材20SiMn低合金钢和0Cr13Ni5Mo不锈钢作为对比材料，对涂层进行了空蚀，液固两相流冲刷磨损及空蚀和冲刷磨损联合作用实验，采用失重法并结合能谱分析，X射线衍射分析及显微硬度测量等手段研究了涂层的显微结构和在不同形式损伤下涂层的性能并分析了原因。结果表明：在20SiMn低合金钢表面激光熔敷形成的Co合金涂层有良好的抗空蚀性能，这与涂层在空蚀过程中发生的应力诱发马氏体相变密切相关。良好的抗空蚀性能有利于提高涂层抗空蚀和冲刷磨损联合破坏，从而使涂层表现出与0Cr13Ni5Mo不锈钢接近的抗联合损伤性能。     

水工混凝土的空蚀试验及抗空蚀性能

利用旋转圆盘空蚀试验装置,通过在拟定水流条件下对不同配合比混凝土材料折抗空蚀试验,测定井分析了该类蚀和的抗空蚀行为。结果表明,水工混凝土在空蚀荷载的交变应力应变和单向应力应变作用下,其空蚀特征参数与疲劳特性指标具有良好的相关关系。     

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。     

不锈钢表面激光熔覆抗空蚀涂层技术研究进展

综述了国内外不锈钢抗空蚀激光表面熔覆技术的研究现状,介绍了该技术的特点,设备和抗空蚀熔覆粉末体系.并对激光熔覆层结构及性能作了较详细的介绍,阐述了熔覆层的抗空蚀性、耐磨蚀性和耐腐蚀性等.还简要介绍了该技术的应用现状,并提出了其今后的发展前景及方向.     

Fe-25Mn-6Si-7Cr形状记忆合金空蚀研究

用旋转圆盘实验机研究了Fe—25Mn—6Si—7Cr形状记忆合金空蚀．结果表明，Fe—25Mn—6Si—7Cr形状记忆合金空蚀是一种疲劳破坏，失效机制为沿晶断裂和晶内蚀坑．Fe—25Mn—6Si—7Cr形状记忆合金空蚀的速度效应小，抗空蚀性能在34m／s和45m／s速度下分别是对比材料0Crl3Ni5Mo不锈钢的1．6倍和7．3倍．伪弹性是F1—25Mn—6Si—7Cr形状记忆合金具有高抗空蚀性能的主要原因．     

Ni基等离子堆焊合金的空蚀行为

使用超声振荡空蚀实验设备研究了Ni基等离子堆焊合金在蒸馏水中的空蚀行为。堆焊合金的显微组织由奥氏体基体，第二相似及共晶组织组成，奥氏体基体的固溶强化以及大尺寸硬质相有效抵卸御射流的冲击，是Ni基等离子堆焊合金具有高的抗空蚀性能的主要原因。     

抗空蚀材料研究应用进展

概括了材料空蚀机理及其影响因素 ,综合评述了材料抗空蚀性与其力学性能、组织结构之间的关系。介绍了抗空蚀材料在应用等方面所取得的进展 ,提出并讨论了目前研究的某些不足之处及今后的研究方向     

新型耐空蚀Cr-Co-Ni-Mn奥氏体不锈钢研究

制备了一种Cr-Co-Ni-Mn含钴奥氏体不锈钢。与304不锈钢比较,研究了其抗空蚀性能,用TEM观察了空蚀试样的组织结构,并测定了该钢种的强度,利用时效处理研究其组织稳定性。结果表明Cr-Co-Ni-Mn含钴奥氏体不锈钢屈服强度、抗拉强度比常用的304不锈钢高,奥氏体组织稳定,空蚀孕育期长,耐空蚀效果好。TEM观察到试样空蚀作用层有ε马氏体组织,这些形变组织有利于吸收应变能,提高材料耐空蚀能力。综合该钢的性能,在耐空蚀领域有潜在的应用前景。     

AC-HVAF非晶和金属陶瓷涂层在压裂液中空蚀行为研究

采用超声空蚀与电化学测试相结合的方法,对AC-HVAF热喷涂非晶金属和金属陶瓷两种涂层在水力压裂液中的空蚀及交互作用规律进行了研究,分析了耐蚀性和硬度在空蚀时的主导作用,确定了空蚀机理。结果表明,压裂液中KCl恶化了涂层的腐蚀性能,进而影响了空蚀行为。涂层在压裂液中的抗空蚀性能是耐蚀性与硬度结合的双变量函数。空化的力学破坏对高硬度涂层的空蚀过程有显著影响,硬度相对较高的金属陶瓷防护涂层的抗空蚀性能优异。压裂工况下,AC-HVAF涂层空蚀损伤是由于气泡溃灭垂直冲击孔隙或缺陷区域,硬相直接被剥离表面。降低孔隙和提高粘结相结合强度有助于提高涂层在压裂液中的抗空蚀性能。     

LF6合金退火制度对抗蚀性能的影响

本文研究了ＬＦ６合金挤压制品退火工艺对合金抗蚀性能的影响。研究发现，采用３２０℃／０．５－１ｈ空冷的最终退火制度代替现行２２０℃／１～４ｈ空冷的最终退火工艺，可使合金消除晶间腐蚀和应力腐蚀倾向，并使阳极化膜呈连续的黄色厚膜，使合金具有良好的抗腐蚀性能。     

20SiMn低合金钢和0Cr13Ni5Mo不锈钢的多相流损伤行为

对水轮机用金属材料20SiMn低合金钢和0Cr13Ni15Mo不锈钢进行旋转圆盘仪空蚀和冲刷磨损单元和组合多相流损伤实验。结果表明，20SiMn低合金钢和0Cr13Ni15Mo不锈钢的冲刷磨损及空蚀和冲刷磨损联合作用损伤累积质量损失－时间曲线均呈线性关系，空蚀和冲刷磨损联合作用对材料造成的损伤显著高于空蚀和冲刷磨损单独作用，空蚀和冲刷磨损的交互作用在空蚀和冲刷磨损联合作中起重要的作用；在空蚀和冲刷损联合作用中，液体空化及随后的空泡溃灭改变了流体中固相颗粒的运动方向，引起固相颗粒的流速增加和攻角改变，从而加剧了固相颗粒对材料表面的损伤。     

Cavitation Erosion Behavior of CrMnN Duplex Stainless Steel in Distilled Water and 3% NaCl Solution

The cavitation erosion (CE) behavior of CrMnN ferrite-austenite duplex stainless steel in distilled water and 3% NaCl solution was investigated by using a magnetostrictive-induced CE facility. The damaged surfaces were observed by scanning electron microscope (SEM). It was found that the CE resistance of CrMnN steel was higher than that of 0Crl3Ni5Mo steel. The mass loss rate of CrMnN steel in distilled water was similar to that in 3% NaCl except at the early stage of CE. The failure mode of ferrite phase was brittle fracture, which had adverse effect on the resistance to CE, while the failure of austenite phase was a ductile failure in CrMnN steel. The excellent resistance to CE was related to the good mechanical properties of austenitic phase and the consumption of CE energy by plastic deformation involving slip and twinning.     

Research on cavitation erosion and wear resistance performance of coatings

Depending on the nature of the working medium and working conditions, corrosive and cavitation damage shall arise to pump’s components. In industrial applications the corrosion-reducing coatings are sprayed on hydraulic components. But it is questionable whether such products actually do help under wear or cavitation loads or not. Abrasive jet wear tests were carried out to determine the wear resistance of coating materials: polymers and ceramics, cast iron, and steel of various types. The samples were loaded for five hours, and finally the wear depth was measured as a determining indicator of the sample’s wear resistance. Results of investigation on anti-erosion performance of epoxy resin, ceramic and Polyurethane (PU) coatings brushed on alloy steel surface were also presented. Cavitation erosion tests were performed on the ultrasonic rig. The mass loss and surface morphology of the specimens were examined by balance analysis and 3-D laser microscopy, respectively. The investigations showed excellent wear-resisting performance of ceramic coatings, which is better than wear-resistance of stainless steel, cast iron and high chrome alloy steel. But the excellent wear-resisting performance could not guarantee a good erosion-resisting performance. The ceramic coatings’ anti-erosion performances were inferior to that of gray cast iron, and hardly comparable to those of stainless steels. The basic factors that influenced coating’s cavitation erosion endurance were adhesion and thickness of coatings. Analysis of coating’s degradation mechanism showed that PU coatings could withstand longer incubation period thus enhancing the materials’ cavitation erosion resistance. Several practical cases were analyzed, showing some guidance for coatings’ application.     

Cavitation erosion resistance of 13/4 and 21-4-N steels

Nitrogen strengthened austenitic stainless steel (termed as 21-4-N steel) in as cast and hot rolled conditions has been investigated as an alternative to 13/4 steel (termed as CA6NM) to overcome the problems of cavitation erosion in hydro turbine underwater parts. The cavitation erosion of 21-4-N and 13/4 steels was investigated by means of an ultrasonic vibration processor. The cavitation erosion is highly dependent on microstructure and mechanical properties. The results show that hot rolled 21-4-N steel is more cavitation erosion resistant than the 13/4 and 21-4-N steels in as cast condition. The eroded surfaces were analysed through optical microscope and scanning electron microscope for study of erosion mechanisms.     

Fe-25Mn-6Si-7Cr形状记忆合金在含沙多相流中的损伤行为

测量Fe-25Mn-6Si-7Cr形状记忆合金在含沙多相流中的损伤抗力,研究了失效机制和损伤抗力的控制因素,并与水轮机叶片用不锈钢0Cr13Ni5Mo进行了对比.结果表明,Fe-25Mn-6Si-7Cr形状记忆合金在含沙多相流中的失效机制主要是泥沙犁削,其损伤抗力因高的局域弹性和高的犁削抗力而优于不锈钢0Cr13Ni5Mo,局域弹性高是其损伤破坏速度效应低和空蚀与泥沙冲刷磨损交互作用小的根本原因.     

SO2 heat exchanger failure

Critical heat exchanger components are usually manufactured from durable steels, such as stainless steel, which exhibit good strength and corrosion resistance. Failure of a heat exchanger occurred due to specification of a plain carbon steel that did not survive service in the SO₂ vapor environment. However, failure analysis showed that cavitation erosion was the responsible failure mechanism, not corrosion as might be expected.     

The erosive wear of mild and stainless steels under controlled corrosion in alkaline slurries containing alumina particles

The erosive wear in an alkaline slurry containing alumina particles of three typical engineering materials, the mild steel BS 6323 (Fe-C), the AISI 410 stainless steel (Fe-Cr-C), and the AISI 304 stainless steel (Fe-Cr-Ni), was carried out, by means of rotating cylinder, three-electrode erosion-corrosion test, with a view to investigation into the roles of the typical elements and the mechanical and chemical properties in the erosive wear under simultaneous controlled corrosion. The total weight loss of erosion-corrosion was obtained by precision weighing and the result was compared and interpreted, for each material, by a full microscopical examination of the erosion-corrosion scars using scanning electron microscopy (SEM). It was found that the overall performance under erosion-corrosion in an descending order was the stainless steels AISI 304, AISI 410, and the mild steel, although the precise difference in performance was dependent upon the process conditions. Such a ranking of performance was not in total consistence with that expected only from the mechanical or the chemical property differences of the materials concerned. The individual contribution of each erosion and corrosion process was thus further separated through corrosion charge conversion using the Faraday's second law and the results were interpreted by discussion, on basis of the experimental and microscopical evidences, of the main factors that influenced the mechanical and wear behaviour, in conjunction with those influencing corrosion and passivity. Finally, schematic diagrams were proposed to outline the typical erosion and corrosion features thus obtained for all the three materials during erosion-corrosion.     

水机材料的抗磨蚀性判据研究

为了证实水机材料的抗磨蚀和抗空蚀性能与材料的常规宏观性能之间的相依关系，选取4种具代表性的材料（碳化钨涂层、NiCr合金涂层、硼不锈钢涂层和钛），进行空蚀和磨蚀试验，并测试了它们的硬度和抗腐蚀性。试验结果表明，材料的空蚀和磨蚀抗力与硬度和抗腐蚀性有着紧密的相依关系:高硬度是抗磨蚀性优的第一判据，较强的抗腐蚀性是第二判据；高抗腐蚀性是抗空蚀性优的第一判据，较高的硬度是第二判据。