Dynamic Characteristics of Lubrication and Wear Prediction of Slipper/Swash-Plate in Axial Piston Pumps

A novel dynamic model describing the slipper posture of the swash plate in axial piston pumps is proposed, taking into account the hydrodynamic and squeezing effects, which involves three degrees of freedom. The variation in the lubricating film thickness and the slipper tilt are accurately calculated. The influence of hydrodynamic effects and charging pressure on the slipper lubrication is discussed. The minimum film thickness, the overturning angle and the azimuth angle are obtained.Then, the trajectory of minimum thickness on the friction surface of the swash plate is predicted, the accuracy of which can be verified with the abrasion distribution of an actual swash plate. Research results can predict the durability and provide theoretical help for the design of the slipper.

Application of simulated annealing algorithm to improve work roll wear model in plate mills

Employing Simulated Annealing Algorithm (SAA) and many measured data, acalculation model of work roll wear was built in the 2 800 mm 4-high mill of Wuhan Iron and Steel(Group) Co. (WISCO). The model was a semi-theory practical formula. Its pattern and magnitude werestill hardly defined with classical optimization methods. But the problem could be resolved by SAA.It was pretty high precision to predict the values for the wear profiles of work roll in a rollingunit. After one-year application, the results show that the model is feasible in engineering, and itcan be applied to predict the wear profiles of work roll in other mills.

真空热轧316L钢/Q355钢和304L钢/Q355钢复合板耐摩擦磨损性能研究

通过在模拟实际生产条件下进行的摩擦磨损试验,研究了真空热轧的316L钢/Q355钢和304L钢/Q355钢复合板的耐摩擦磨损性能。结果表明:以相同的试验参数摩擦磨损试验60 min后,304L钢/Q355钢复合板的质量损失为132.7 g,而316L钢/Q355钢复合板的为115.2 g,即后者的耐磨性优于前者;摩擦磨损试验后,304L钢/Q355钢复合板的平均位错密度为4.19×10^(14)m^(-2),而316L钢/Q355钢复合板的为5.23×10^(14)m^(-2);304L钢/Q355钢复合板在摩擦磨损试验中产生的马氏体体积分数为2.1%,而316L钢/Q355钢复合板的为3.0%。

Wear and Corrosion Resistance of Electroless Plating Ni-P Coating on P110 Steel

In order to improve the surface performance and increase the lifetime of P 110 oil casing tube steel during operation, electroless plating was conducted to form Ni-P coating onto its surface. The surface morphology/element distribution and phase constitution of the Ni-P coating were analyzed using scanning electron microscope （SEM） equipped with energy dispersive spectrometry （EDS） and X-ray diffraction （XRD）. Tribological and electrochemical measurement tests were applied to investigate the wear and corrosion resistance of P110 steel and the Ni-P coating. The results showed that a uniform and compact, high phosphorous Ni-P coating was formed. The obtained Ni-P coating indicated certain friction-reduction effect and lower mass loss during friction-wear tests. The Ni-P coating also exhibited higher corrosion resistance in comparison with bared P 110 steel. The obtained N i-P coating has significantly improved the surface performance of P110 steel.

Corrosion and wear properties of electroless Ni-P plating layer on AZ91D magnesium alloy

A direct electroless Ni-P plating treatment was applied to AZ91D magnesium alloy for improving its corrosion resistance and wear resistance. Corrosion resistance of the Ni-P coatings was evaluated by potentiodynamic polarization and immersing experiments in 3.5% NaCl solution. The wear resistance of the coatings was investigated by the wear track and the mass change after ball-on-disk experiment. The results show that corrosion resistance and wear resistance of the AZ91D alloy are greatly improved after direct electroless Ni-P plating. No discoloration is noticed until 4 d of immersion in 3.5% NaCl solution. Potentiodynamic polarization experiments show that the free corrosion potential of magnesium alloy is shifted from -1 500 mV to -250 mV and passivation occurs at 1 350 mV after direct electroless plating. The friction coefficients and wear rates of Ni-P coating and Ni-P coating after tempering are 0.10-0.351, 9.038×10-3 mm3/m and 0.13-0.177, 3.056×10-4 mm3/m, respectively, at a load of 1.5 N with dry sliding. Although minor hurt on corrosion resistance was caused, significant improvement of wear resistance was obtained after tempering treatment of the coating.

MICROSTRUCTURE AND MECHANISM OF A NEW TYPE OF Ni－Fe－W－P－S WEAR－RESISTANT BRUSH PLATING LAYER

A new type of Ni-Fe-W-P-S wear-resistant brush plating layer isdeveloped, and its microstructure is investigated at different temperatures by usingX-ray diffractometer, transmission electron microscope and surface analytical appa-ratus. The results revealed that the plating layer is composed of amorphous and mi-crocrystalline matrix and intermetallic compounds. Such a microstructure is verybeneficial to improving its wear-resistance.This new type of plating layer can replacethe chromium plating technique which is very poisonous for human health and harm-ful to the agricultural production.

Properties and Application of Slide Nozzle Plate for High Oxygen Steel

Several kinds of slide nozzle plate such as A12O3-C-ZrO2, MgO, Al2O3, Spinel-C and A12O3-C SN plate for high oxygen steel used in BaoSteel have been analysed, the appearance and size of the SN plate after using have been measured. The Al2O3-C SN plate has longer service life in casting high oxygen steel, and the wear mechanism of different SN plates is discussed.

Friction and Wear Characteristics of Brush Plating Ni/nano-Al2O3 Composite Coating under Sand-Containing Oil

Ni-matrix composite coating containing AI2O3 nano-particles is prepared by brush plating. The effects of the nano-particles on the microstructure, microhardness and tribological properties of the composite coating under the lubrication of a diesel oil containing sand are investigated. The results show that the microstructure of the composite coating is finer than that of the pure nickel coating due to the codeposition of the nano-particles. When the nano-particle concentration in the electroplating bath reaches 20 g/L, the microhardness, and wear resistance of the composite coating is as much as 1.6 times and 1.3-2.5 times of those of the pure nickel coating respectively. The main hardening mechanism of the composite coating is superfine crystal grain strengthening and dispersion strengthening. The composite coating is characterized by scuffing as it slides against Si3N4 under the present test conditions.

Enhanced wear and fatigue properties of Ti-6AI-4V alloy modified by plasma carburizing/CrN coating

In this study, a newly developed duplex coating method incorporating plasma carburization and CrN coating was applied to Ti-6Al-4V and its effects on the wear resistance and fatigue life were investigated. The carburized layer with approximately150 μm in depth and CrN coating film with 7.5 μm in thickness were formed after duplex coating. Hard carbide particles such as TiC And V4C3 were formed in the carburized layer. XRD diffraction pattern analysis revealed that CrN film had predominant [111] and [200] textures. The hardness （Hv） was significantly improved up to about 1960 after duplex coating while the hardness value of original Ti-6Al-4V was 402. The threshold load for the modification and/or failure of CrN coating was measured to be 32N using the acoustic emission technique. The wear resistance and fatigue life of duplex coated Ti-6Al-4V improved significantly compared to those of un-treated specimen. The enhanced wear resistance can be attributed to the excellent adhesion and improved hardness of CrN coating film for the duplex coated Ti-6Al-4V. The initiation of fatigue cracks is likely to be retarded by the presence of hard and strong layers on the surface, resulting in the enhanced fatigue life.

枪管用环保镀层摩擦行为研究

传统枪管内膛表面采用的六价铬镀层,高温耐磨性好,但对环境污染严重。为开发环保镀层,采用超景深三维显微镜、扫描电子显微镜表征了室温和高温(400℃)摩擦磨损试样,对比分析了六价铬、三价铬、钴-镍和镍-钨四种电镀层的磨损特征。研究结果表明:在500℃定性回火后,三价铬、镍-钨、六价铬和钴-镍镀层硬度依次递减,与六价铬层相比,三价铬层脆性大,镍-钨和钴-镍镀层韧性高;室温下与H62黄铜对摩后,六价铬和三价铬镀层摩擦程度较轻,钴-镍和镍-钨镀层呈现明显粘着特征,二者摩擦系数高于两种铬层;400℃下与08Al钢对摩后,六价铬呈粘着磨损特征,摩擦程度较大;三价铬层摩擦系数相对较高;镍-钨镀层呈磨粒磨损特征,摩擦系数与六价铬接近,摩擦程度相对较轻。

基于电接触强化的铝合金表面电刷镀镍层改性研究

[目的]对铝合金进行表面处理可提高其硬度和耐磨性,拓宽铝合金材料在机械零件方面的应用。[方法]采用电刷镀技术在1060铝合金表面制备Ni镀层,再通过电接触强化技术对Ni镀层进行改性。采用扫描电子显微镜和维氏硬度计考察了Ni镀层电接触强化前后的微观组织和显微硬度。通过摩擦磨损试验对比了1016铝合金及Ni镀层电接触强化前后的耐磨性。[结果]经电接触强化后,Ni镀层内部的裂纹及孔洞类缺陷减少,晶粒间隙减小,致密性提高,显微硬度增大到524.4~560.3 HV0.1范围内。1016铝合金在摩擦磨损试验后存在较深的犁沟和剥落,耐磨性较差。Ni镀层的耐磨性优于1016铝合金,但在摩擦过程中会发生剥落。经电接触强化的Ni镀层在摩擦过程中摩擦因数平稳,表面只是轻微擦伤,耐磨性最佳。[结论]结合电刷镀镍和电接触强化技术可显著提高铝合金的表面性能。

Distribution Performance Analysis and Experimental Research on the Port Plate Pairs of Low Speed High Torque Seawater Hydraulic Motor

The current research of seawater hydraulic motor mainly focused on piston motor and vane motor, but seldom regarded low speed high torque seawater hydraulic motor. Low speed high torque seawater hydraulic motor as a kind of energy conversion device and actuator plays an important role in seawater hydraulic transmission system. However, the physical and chemical properties of seawater, such as low viscosity, high causticity and poor lubrication, result in numerous problems. In this paper, the flow distribution characteristics of port plate pairs for the seawater hydraulic motor are investigated, and the leakage flow and power loss models of port plate pairs are established. Numerical simulations are carried out to examine the effects of water film, inlet pressure and rotating speed on the pressure distribution and leakage flow. And the friction and wear tests of port plate pairs are also carried out. Moreover, the test system of the seawater hydraulic motor is constructed and the performance of prototype with no-load or loading is conducted. The results indicate that the clearance of port plate pairs and inlet pressure have a significant effect on distribution characteristics, but the effect of rotating speed is not very obvious. The experimental results show that the minimum error rate can be maintained within 0.3% by the proposed flow model and the counter materials of 316 L against carbon-fiber-reinforced polyetheretherketone(CFRPEEK) are suitable for the port plate pairs of seawater hydraulic motor. Finally, based on the seawater hydraulic experiment platform, the volumetric efficiency of no-load and loading are obtained that the maximum can achieve 94.71% and 90.14%, respectively. This research work may improve the flow distribution performance, lubrication and the friction and wear properties, enhance energy converting efficiency of port plate pair and provide theoretical and technical support for the design of highperformance water hydraulic components.

多功能融合电机泵马达仿生非光滑表面配流副摩擦及润湿性研究

以多功能融合电机泵马达配流副为研究对象,利用仿生非光滑表面效应设计出几种不同凹坑排布的配流盘,并通过不同工况下光滑表面和非光滑表面配流盘的对比试验,探讨非光滑表面对配流副润滑性能和减摩性能的影响。试验结果发现:非光滑表面比光滑表面有着更好的减磨减阻特性,其中最大减阻可达46.3%,减磨总体超过53%;非光滑表面中的凹坑可以储存试验中产生的磨屑和杂质,还可以储存海水,在润滑条件不良时凹坑内部海水可被带入到摩擦面从而改善润滑状态;试验后配流副试样接触角会降低,表面能会提升,这说明摩擦磨损试验使得配流副试样更加亲水,这有助于海水润滑膜的形成,从而降低摩擦面的摩擦磨损。

耐磨零部件的电刷镀铬修复

[目的]某耐磨镀铬零部件长期依赖进口,在服役过程中会出现磨损、腐蚀等问题,对其进行修复再制造不仅符合绿色制造的理念,更可以大幅降低设备的运维成本,减少材料消耗。[方法]使用电刷镀铬技术对该零部件进行修复,对比了修复件和全新件表面Cr镀层的微观组织、表面粗糙度、显微硬度、耐磨性及耐蚀性,以探究电刷镀铬修复用于该零件的可行性。[结果]修复件的Cr镀层为光亮的银灰色,其微观形貌、显微硬度、表面粗糙度和耐蚀性都与全新件的Cr镀层相近,耐磨性则更优。[结论]电刷镀铬可用于修复该类零件,本文的研究结果有助于提高相应设备的国产化程度。

平环强磁选机聚磁介质齿板开发研究

选用酒钢自产含碳量低,含铬量适中的超纯铁素体不锈钢,通过改良工艺、自行研制、加工平环强磁选机聚磁介质齿板开发出一种导磁性能好,工作场强高,耐磨、耐腐蚀性能好,分选指标优良的聚磁介质齿板。完成新开发聚磁介质齿板实验室、生产现场导磁性能、选别指标测试试验。在精矿品位相当的前提下,新开发聚磁介质齿板平均金属回收率比外购聚磁介质齿板金属回收率提高4.36个百分点。

一种基于优化VMD-CWT-CNN的柱塞泵配流盘磨损状态识别方法

为解决一维振动信号难以充分挖掘表达状态特征信息以及柱塞泵配流盘磨损早期识别问题,基于卷积神经网络(Convolutional neural networks,CNN)优秀的图像处理能力,提出了一个优化VMD-CWT-CNN模型。首先,采用连续小波变换(Continuous wavelet transform,CWT)对信号进行预处理,得到信号的二维时频图,作为CNN模型的一路输入,将状态识别问题转化为CNN图像识别问题。其次,基于相关系数对变分模态分解(Variational mode decomposition,VMD)参数优化后,利用优化VMD对振动信号进行预处理,再以相关系数和峭度值最大为优选原则,甄选出三组蕴含故障特征的本征模态函数(Intrinsic mode function,IMF),将其重组为三通道一维信号,作为CNN模型的另一路输入。最后,在CNN模型中将两路信息汇聚并得到柱塞泵配流盘磨损状态识别分类结果。实验中,此方法分别采用优化VMD和CWT对振动信号预处理,再结合CNN对磨损状态进行分类。实验结果表明,该方法对于配流盘磨损的三种状态的识别效果显著优于单路输入的CNN模型以及典型的深度学习方法和机器学习分类器。因此,优化的VMD-CWT-CNN方法可以更准确地实现柱塞泵配流盘磨损状态识别。

CrN涂层制备中氮气比例对耐磨抗黏附性能的影响

采用多弧离子镀技术在38CrMoAl样片表面制备CrN涂层,利用扫描电子显微镜、纳米压痕仪、摩擦磨损试验机、X射线衍射仪及接触角测量仪,研究了氮气比例对CrN涂层耐磨抗黏性能的影响。结果表明,随着氮气比例的增加,CrN涂层由Cr、Cr_(2)N和CrN的混合相向CrN单相转变;CrN涂层磨损率远低于基体磨损率,CrN⁃65涂层的磨损率最低仅为1.01×10^(-6)mm^(3)/(N·m),低于基体磨损率一个数量级。所有CrN涂层表面均表现出疏水性;聚碳酸酯(PC)熔体高温接触角试验中,CrN⁃15涂层与PC熔体的高温接触角最高为110.8°,高于基体的102.2°;经过低温退火处理后,所有表面与PC熔体的高温接触角均降低,但是CrN⁃15涂层退火后仍能保持最高的高温接触角(102.9°),明显高于退火后基体的高温接触角(85.3°),表现出最佳的抗黏附性能。CrN⁃15涂层表现出较好的耐磨性和抗黏附性,综合性能较好,为CrN涂层在塑料加工螺杆和注塑模具表面应用提供一定的技术支撑。

镀银铜材料在大电流条件下的载流微动磨损特性

利用化学电镀方法在T2紫铜管表面镀银制备镀银铜试样,采用自主研制的切向微动磨损试验设备在圆柱/圆柱的正交点接触模式下进行室温载流切向微动磨损试验,探究了镀银铜试样在5 A电流以及不同法向载荷(5,10,15 N)和位移幅值(30,50,70,100μm)下的载流微动磨损行为及其磨损机制。结果表明:随着位移幅值的增加,镀银铜试样的载流微动磨损程度加剧,随着循环次数的增加,不同位移幅值下的摩擦因数整体呈先减小后增大最后趋于稳定的趋势,而接触电阻呈相反趋势,不同位移幅值下稳定阶段的摩擦因数相差不大;随着载荷的增加,载流微动磨损程度先变大后变小,当载荷为10 N时,磨损程度最大,此时有效接触面积较大,接触电阻较低;随着载荷的增加,稳定阶段的摩擦因数增大。镀银铜试样在磨损初期的磨损机制主要黏着磨损和氧化磨损,在磨损后期主要为磨粒磨损、氧化磨损和剥层,且随着循环次数的增加,氧化磨损程度加剧。

低浓度硫酸铜对化学镀Ni-P镀层微观结构及性能的影响

为改善镍磷(Ni-P)镀层的表面质量、提高Ni-P镀层的性能,在化学镀Ni-P镀液中加入少量的硫酸铜(CuSO_(4)·5H_(2)O)制备Ni-P镀层。利用扫描电镜、能谱仪、X射线衍射仪分析了镀层的表面形貌、成分和结构,研究了CuSO_(4)·5H_(2)O浓度对镀层的微观结构、表面粗糙度、光泽度、硬度、耐磨性和耐蚀性的影响。研究表明:当CuSO_(4)·5H_(2)O浓度为0.1 g/L时,镀层为致密的非晶态节瘤状组织,具有最佳的耐蚀性;当CuSO_(4)·5H_(2)O浓度为0.2 g/L时,镀层表面质量最好,硬度高、耐磨性优异,但镀层中出现少量微晶态Ni-Cu固溶体,耐蚀性下降;当CuSO_(4)·5H_(2)O浓度超过0.2 g/L后,镀层为混晶态菜花状组织,镀层表面的质量和耐蚀性随CuSO_(4)·5H_(2)O浓度的增加不断恶化。

结晶器铜板表面HVOF喷涂NiCrCoBSi多主元合金涂层的高温磨损性能

针对连铸结晶器铜板在服役过程中的磨损失效问题,采用超音速火焰喷涂(HVOF)技术在结晶器铜板表面制备了NiCrCoBSi自熔性多主元合金涂层,以提高铜板的耐磨性能。利用XRD、SEM、TEM等方法研究了NiCrCoBSi涂层的微观结构;借助摩擦磨损设备对其耐磨性进行评价,并与市场化占有率最高的电镀NiCo涂层进行对比。结果表明:NiCo涂层为单相面心立方(FCC)固溶体结构,而NiCrCoBSi涂层的主要物相包括FCC固溶体、CrB和M_(23)C_(6)。与NiCo涂层相比,NiCrCoBSi涂层的硬度提高了95%,而断裂韧性只下降了5.4%。磨损测试后发现两种涂层的磨损机制均以黏着磨损、疲劳磨损为主,伴随着少量磨料磨损。NiCrCoBSi涂层表现出优异的耐磨性和较低的摩擦因数,其磨损率较NiCo涂层降低了81%。NiCrCoBSi涂层耐磨性较高的主要原因是其较高的硬度、内部的各种硬质耐磨相以及磨损表层的加工硬化。这是因为在循环载荷作用下,涂层产生塑性变形,涂层的硬质相在塑性变形过程中被切割、旋转,导致碳化物及硼化物被细化和球化,从而提升了磨损表层的硬度。制备了具有优异高温耐磨性能的NiCrCoBSi自熔性多主元合金涂层,为长寿命铜及其合金涂层的开发提供了理论依据和技术参考。