一种旋转式液固两相流冲蚀磨损试验装置的研制

针对目前液固两相流冲蚀磨损试验装置存在实际冲角误差大、浆体浓度不均匀等问题,研制了一种旋转式冲蚀磨损试验装置。该装置允许的冲角范围为0°～90°,冲击速度为0～28.5m/s连续可调,利用搅拌叶片和导流槽实现不同冲击速度下浆体浓度的均匀性,具有速度稳定、可同时测试8个不同冲角下的试样、操作方便等特点。对低碳钢在不同冲击速度和冲角下的试验表明,所测得试验数据误差在6.8%以内,冲蚀磨损规律与经典结论一致。因此,该装置有望作为一种准确可靠的冲蚀磨损试验研究新平台而应用于耐冲蚀磨损优化设计和寿命预测等领域。     

砂浆冲蚀磨损特性研究

用自制的砂浆冲磨损试验机在水－石英砂浆冲蚀条件下，对纯铝、27SiMn钢和高铬铸铁等金属材料的磨损行为进行了试验，研究了不同材料的砂浆冲蚀磨损率与冲蚀速度及冲蚀角度的关系，分析了砂浆冲蚀磨损的特性和机理，提出了一种砂浆冲蚀磨损的刺入机制。     

冲蚀磨损试验机的改进及实验研究

为模拟重介旋流器工况,合理评定内衬材料耐磨性,在旋转式浆体冲蚀磨损试验机的基础上,通过改进搅拌系统和试样安装方式,设计一种旋流式冲蚀磨损试验机。该试验机通过不锈钢+尼龙叶片二级搅拌系统实现了对浆料的均匀搅拌,在料桶内壁安装试样模拟了重介旋流器物料对内衬材料的冲蚀磨损工况,试验冲蚀角度范围为0°~90°。通过流体力学计算得出浆料对试样的冲蚀速度可达2.4　m/s,对纯铝的冲蚀磨损试验表明,试验机的数据重现性误差小于16%,稳定性误差小于17%。     

旋流式冲蚀磨损试验机的设计及实验研究

为模拟重介旋流器工况,合理评定内衬材料耐磨性,在旋转式浆体冲蚀磨损试验机的基础上,通过改进搅拌系统和试样安装方式,设计一种旋流式冲蚀磨损试验机。该试验机通过不锈钢+尼龙叶片二级搅拌系统实现了对浆料的均匀搅拌,在料桶内壁安装试样模拟了重介旋流器物料对内衬材料的冲蚀磨损工况,试验冲蚀角度范围为0°~90°。通过流体力学计算得出浆料对试样的冲蚀速度可达2.4 m/s,对纯铝的冲蚀磨损试验表明,试验机的数据重现性误差小于16%,稳定性误差小于17%。     

复合尼龙涂层的腐蚀—冲蚀磨损特性

本文对尼龙涂层及尼龙+5％Al_2O_3陶瓷颗粒和尼龙+5％SiC晶须复合涂层进行了腐蚀—浆体冲蚀磨损试验研究。研究了砂浆的pH值,冲击速度等参数对涂层的腐蚀冲蚀磨损的影响,对涂层表面的组织结构和形貌进行了观察分析,探讨了复合尼龙涂层的腐蚀冲蚀磨损机理,建立了V_e-pH-U腐蚀—冲蚀磨损三维图。     

离心压缩机叶轮材料FV520B冲蚀规律和机理的研究

利用高速冲蚀试验系统,以7 μm、10 μm、14 μm多角氧化铝微粒为冲蚀颗粒,在120 ~ 210 m/s冲击速度范围内,对离心式压缩机叶轮材料FV520B在模拟压缩机叶轮高速粒子冲蚀环境下的冲蚀规律进行了系统的试验研究。对冲蚀表面形貌进行分析,研究冲蚀磨损机理。结果表明：参与冲蚀的粒子质量在5 ~ 80 g之间时,冲蚀率先增加后减小即为冲蚀过渡期,冲蚀粒子质量大于80 g后冲蚀率趋于平稳,进入冲蚀稳定期;高、低强度的两种FV520B材料,均呈现出典型的塑性材料的冲蚀特性,最大冲蚀率分别出现在24°、18°的冲击角度附近;高强度FV520B在24°和90°冲击角度时的速度指数分别为3.37和3.68,速度指数随冲击角度的增大而增大;FV520B冲蚀磨损的实质是微切削与变形磨损共同作用,在低角度冲蚀时,以微切削磨损为主,而在大于60°的高角度冲蚀,以变形磨损为主。     

砂粒粒径对航空涡轴发动机压气机叶片冲蚀磨损的影响研究

高原、沙漠和沿海等服役环境中不同粒径的砂粒不可避免地对涡轴发动机压气机叶片造成冲蚀磨损,破坏叶片叶型和动力学特性,严重危及涡轴发动机使用寿命和直升机飞行安全。基于Finnie冲蚀磨损理论推导了颗粒对金属表面的磨损率表达式,分析颗粒粒径对材料冲蚀磨损率的影响,以某型涡轴发动机压气机动叶和静叶为研究对象,设计搭建砂粒冲击速度测试装置和钛合金冲蚀磨损实验装置,通过典型砂粒粒径下冲蚀磨损实验获取磨损率表达式中与靶材材料和冲击速度相关的关键参数,结合气固两相流动力学分析开展砂粒粒径对压气机动叶和静叶冲蚀磨损的影响研究。结果表明：砂粒粒径与冲击速度存在内在关联,材料冲蚀磨损率与砂粒冲击速度呈幂函数关系。实验条件下,砂粒粒径由177 μm增至423 μm时,其冲击速度平均降低约17%。压气机动叶和静叶的磨损集中区域不随砂粒粒径的改变而变化,但磨损程度差异明显,其中177 μm砂粒对动叶和静叶造成的最大冲蚀磨损率浓度值相比423μm砂粒分别增加91%和131%。研究结果为涡轴发动机压气机叶片抗磨损设计提供了理论参考。     

低冲蚀角下40Cr冲蚀与空蚀耦合磨损特性研究

基于CFD理论,数值模拟了低冲角下(冲蚀角α40°)冲蚀和空蚀耦合磨损的流场特性,并将数值分析结果与实验结果进行对比,研究了40Cr在低冲角下耦合磨损的失效特性。研究发现:1)耦合磨损的破坏程度随着冲蚀角的增加先增大后减小降,在临界角α=30°时磨损最严重,此时耦合磨损流场的溃灭冲击压强达到了最大的1×107Pa,在这种高强度冲击的反复作用下,材料更容易发生疲劳失效;2)当α30°时,40Cr材料表面的磨痕主要为微切削犁沟,并有少量的针孔状蚀坑;3)当α30°时,材料表面的磨痕主要为瞬时高温氧化和疲劳剥落引起的夹杂着白色氧化铁颗粒的蚀坑。40Cr试件失重量随冲蚀角变化趋势与三次样条曲线吻合得很好。     

冲击形式产生的冲蚀、空蚀和腐蚀联合磨损试验研究

舰船等海洋运输装备在海水中行驶时,船体表面受到含沙海水的冲蚀磨损,舰船行驶速度变化引起的空蚀磨损,以及海水的腐蚀磨损,因此舰船表面材料的破坏形式是冲击式的冲蚀、空蚀和腐蚀联合磨损。为了研究联合磨损的影响因素,研制冲蚀、空蚀和腐蚀联合磨损试验台,并实验研究沙粒浓度、沙粒尺寸、含盐浓度以及冲蚀速度对45钢试件的联合磨损影响规律。实验结果表明:冲蚀、空蚀和腐蚀联合磨损程度强于冲蚀和空蚀交互磨损或单纯腐蚀磨损,在较低的沙粒浓度和较低的含盐浓度条件下,金属材料联合磨损质量损失与沙粒浓度、沙粒尺寸、含盐浓度和冲蚀速度均成正比关系。磨损面形貌分析表明:随着沙粒浓度、沙粒尺寸、含盐浓度、冲蚀速度的增加,试件表面的冲蚀沟和空蚀孔的磨痕深度和面积增大,而在人造海水中,试件表面不仅存在冲蚀沟和空蚀孔,还产生了腐蚀坑。     

钢在气 固流体中高温冲蚀磨损及其对策研究

本成果包括两部分内容一、高温冲蚀磨损强化模拟试验装置模拟省煤器工况的流场式高温冲蚀磨损强化试验装置。工作温度：室温～500℃可调；气流速度：18～30m／s；磨料输送量：20～100kg／　h。试验数据稳定，与现场实测数据一致，本装置填补了国内空白。二、表面强化层的优选采用六类十余种不同方法和材料对20#钢进行强化，在攻角45°、流速30．8m／s、温度500℃、磨粒输送量42．6kg／h的条件下进行优选试验，优选出的合金喷溶强化层及防磨涂料，经淮北发电厂和淮南平圩发电厂省煤高温管上试用半年以上证明：A1号合金喷溶强化层，能使省煤…     

Control and evaluation of particle impact conditions in a sand erosion test facility

For the prediction of actual damage to plant component materials and for making the erosion mechanisms clear, it is important to control and to evaluate the particle impact conditions in a testing facility. A sand blast type erosion test rig, which can achieve the particle impact velocities up to 135 m s⁻¹ and a wide range of impact angles has been constructed. The key factors in particle impact conditions of particle flux, impact velocity and impact angle were examined. The relative distance between particles and particle size was discussed, as the particle flux affected erosion rate of material. A new method was proposed to determine particle velocities in this facility. The theoretical velocity of the particle calculated by the equations of particle motion was compared with the experimental results. The divergence of particles from a geometrical angle was evaluated by measuring surface roughness of the specimens. Although some spread of the particles were observed surrounding the central damage area of the specimen surface, the greatest amount of damage was concentrated in the center. As a result, it was found that particle impact conditions were well controlled in this testing unit.     

Measurements of plastic strain around indentations caused by the impact of round and angular particles, and the origin of erosion

The aim of this paper is to examine plastic strain distributions around indentations and to consider the mechanisms of erosion damage caused by solid particle impact. A WC ball and an angular SiC particle of 3 mm in diameter were used to compare the effect of particle shape on plastic strain. Measurements of principal shearing strain distributions around the indentations were performed on surfaces of aluminum, iron and cast iron at impact angles of 20°, 30°, 40°, 60° and 90° at impact velocities from 50 to 200 m s⁻¹. It was found that the impact angle dependence was roughly consistent with the maximum principal shearing strain and erosion damage data, which have been published in previous papers and obtained during additional works in this study. The surface topography of the impact craters suggested that depth, contact area and volume of indentation are affected by the particle density and the hardness of both particle and target material. Measurements of volume ratio of lips to craters proved that material removal did not necessarily occur at a single impact of the WC ball, but occurred at the impact of the angular SiC particle at low impact angles. It is concluded that the origin of erosion is probably attributed to the conjoint actions of high plastic strains followed by subsequent removal and the cutting process caused by particle impact.     

Electrochemical behaviour of stainless steel 304 alloy in erosion–corrosion conditions and synergism effect

Abstract

A study has been made of the erosion–corrosion behaviour of stainless steel (SS) 304 in tap water in the presence and the absence of solid particles. Water at ambient temperature impinged in various angles (15–90°) on specimen surfaces at different velocities (7·85–14 m s^–1) and sand concentrations (0·43–2%). In this research, potentiodynamic, electrochemical impedance spectroscopy and weight loss measurements were used to study the damage mechanism and to estimate corrosion rate. The SEM micrographs and optical microscopy images were used to study the corrosion morphology. Under test conditions, protective passive film and non-protective film formations formed on SS 304 surface. It was found that maximum corrosion–erosion rate happened at the impact angles between 60 and 75°. The synergism effect was positive in all conditions and it was greater for the lower angles, the higher velocities and the higher solid contents.     

Effect of impact angle on the slurry erosion–corrosion of 304L stainless steel

This communication describes an investigation of the effect of impact angle on slurry erosion–corrosion of stainless steel using a new slurry erosion rig. With the new apparatus, it is possible to measure the individual erosion events under impact as both electrochemical current/time transients, and mechanical transients through acoustic emission (AE) simultaneously. Each sharp rise observed in the electrochemical current transient under particle impact is accompanied by an AE event. These sharp current rises are attributed to the rupture or removal of the oxide film on the surface by the abrasive particles. The correlation between the current rise and the maximum of the AE event, although scattered, shows an increase with decreasing impact angle. The current transients due to individual erosion events show that on the average, the current rise is greater and the rise time is longer at oblique angles compared with those at normal incidence. The degree of denudation of the metal surface by individual particle impingements, the process which strips the surface of its passivity, increases at more oblique angles. Weight loss measurements demonstrate that the synergistic effect between erosion and corrosion is enhanced by a more oblique angle of impact. The origin of the synergism is discussed.     

浆液冲击角度对Cr30A高铬铸铁冲蚀行为的影响

在模拟湿法脱硫浆液流动环境中,研究了NaCl溶液+石英砂酸性浆液冲击角度(与试样冲击表面夹角)对Cr30A高铬铸铁冲蚀行为的影响.结果表明:在浆液以60°和30°角度冲击铸铁后,在腐蚀与磨损的交互作用下铸铁的质量损失较大;浆液垂直冲击铸铁后,铸铁的质量损失较小,质量损失的主要原因是冲击磨损;浆液平行冲击铸铁后,铸铁的质...     

Erosion wear behavior of laser clad surfaces of low carbon austenitic steel

Austenitic steel surfaces are laser cladded using a 4 kW continuous wave CO₂ laser with coaxial powder feeding nozzle to investigate the improvement in slurry erosion characteristics. Colmonoy-6 and Inconel-625 are cladded on AISI 316L steel and AISI 304L steel, respectively by laser cladding. Initially, single-pass clad track is overlaid to optimize the laser processing parameters, namely scanning speed and powder feed rate to obtained a sound clad. Minimum cracks, porosity and distortion were found at scanning speed of 0.1 m/min and powder feed rate of 12 g/min. For these parameters, the dilution was 17.33% for Colmonoy-6 and 40% for Inconel-625. To clad large surface area, the optimized laser processing parameters were used to deposit the clad tracks with 60% overlap. Maximum surface hardness of 746 VHN is obtained in case of Colmonoy-6 clad on AISI 316L steel and is 352 VHN in case of Inconel-625 clad on AISI 304L steel. EDAX analysis shows higher degree of mixing of substrate material in the clad pool of Inconel-625 than Colmonoy-6. The results of slurry erosion test of Colmonoy-6 clad surface have shown improvement in erosion resistance of the order of 1.75–4.5 times of the substrate AISI 316L steel at all impact angles and the maximum wear angle has also increased which can be attributed to the increase in the surface hardness. However, Inconel-625 laser clad surface has shown little improvement in erosion resistance of the substrate AISI 304L steel at shallow impact angles with no significant improvement at normal impact condition. The SEM micrographs of worn out Colmonoy-6 clad surfaces at shallow impact angles show that the material is removed mainly by micro-cutting which increases with increase in the impact angle.     

Sand-water slurry erosion of carburized AISI 8620 steel

The erosion behavior of carburized AISI 8620 steel for sand slurry service was investigated. The jet impingement type of test was used where sand slurry is directed at flat specimens to determine the erosion rates and mechanism of erosion. The effects of steel heat treatments, slurry velocities and particle concentrations on erosion rates were investigated.     

浮标入水冲击仿真分析

浮标在空投入水瞬间承受的巨大冲击载荷,有可能损坏浮标外壳及内部元件。掌握浮标以不同姿态、不同速度入水时所受的冲击载荷对提高浮标可靠性具有重要意义。文中利用ANSYS/ LS-DYNA建立了浮标入水的有限元模型,计算了浮标以不同姿态、不同速度入水时所受的冲击载荷及入水速度变化等,并分析了浮标外壳的强度。通过仿真结果分析,总结出浮标入水冲击的规律,可作为浮标结构设计的依据。     

Slurry Erosion–Corrosion of Carburized AISI 5117 Steel

The erosion–corrosion of carburized and untreated low alloy steel (AISI 5117) has been investigated using slurry whirling-arm test rig. Erosion–corrosion tests were carried out in slurries composed of sand particles and either tap water or 3 % NaCl solution. The tests were carried out with particles concentration of 1 wt% and slurry stream impact velocity of 15 m/s. Silica sand having a nominal size range of 250–355 μm was used as an erodent. It has been shown that the erosion and erosion–corrosion resistance of AISI 5117 low alloy steel can be effectively improved by carburizing for all impact angles. However, the effectiveness of carburizing was the highest for an impact angle of 45°, where the erosion and erosion–corrosion resistance were increased by 60–40 %, respectively, compared with that of the untreated material. The results showed that the treated and untreated specimens behaved as ductile materials under erosion and erosion–corrosion tests, and the maximum mass loss occurred at an impact angle of 45°. SEM analysis showed that the erosion tracks developed on the untreated specimens were wider and deeper than that formed on the carburized specimens for erosion and erosion–corrosion tests.     

The erosion of aluminum by solid particle impingement at normal incidence

A rotating arm apparatus was used to study the erosion of polycrystalline aluminum by 1.58 mm diameter WC-6% Co spheres impinging at normal incidence. Dynamic hardness values were obtained from measurements of the impact craters and compared with corresponding quasi-static values. In addition, material removal was monitored gravimetrically, and quantitative information was obtained on threshold and incubation phenomena and steady state erosion behavior. The variation of the velocity dependence of erosion with the number of particle impacts was derived from these data. Supporting scanning electron microscope studies suggest that the mechanism of material removal responsible for ductile erosion at near normal incidence is somewhat different from that which operates at shallower angles. The similarities and differences between these mechanisms are discussed, and it is suggested that together they account for the characteristic variation of ductile erosion with angle of impingement.