A new approach for prediction of the wear loss of PTA surface coatings using artificial neural network and basic,kernel-based,and weighted extreme learning machine

Wear tests are essential in the design of parts intended to work in environments that subject a part to high wear.Wear tests involve high cost and lengthy experiments,and require special test equipment.The use of machine learning algorithms for wear loss quantity predictions is a potentially effective means to eliminate the disadvantages of experimental methods such as cost,labor,and time.In this study,wear loss data of AISI 1020 steel coated by using a plasma transfer arc welding(PTAW)method with FeCrC,FeW,and FeB powders mixed in different ratios were obtained experimentally by some of the researchers in our group.The mechanical properties of the coating layers were detected by microhardness measurements and dry sliding wear tests.The wear tests were performed at three different loads(19.62,39.24,and 58.86 N)over a sliding distance of 900 m.In this study,models have been developed by using four different machine learning algorithms(an artificial neural network(ANN),extreme learning machine(ELM),kernel-based extreme learning machine(KELM),and weighted extreme learning machine(WELM))on the data set obtained from the wear test experiments.The R2 value was calculated as 0.9729 in the model designed with WELM,which obtained the best performance among the models evaluated.

Determination of Muzzle Velocity Loss by Bore Wear Pattern

A method to determine muzzle velocity loss according to the actual measured bore wear pattern is proposed.Therefore,it is unnecessary to conduct live firing and other experiments for determination of muzzle velocity loss.It has been applied to a national military standard since July 1,2004.

Friction and wear properties of copper matrix composites reinforced by tungsten-coated carbon nanotubes

Carbon nanotubes （CNTs） were coated by tungsten layer using metal organic chemical vapor deposition process with tungsten hexacarbonyl as a precursor. The W-coated CNTs （W-CNTs） were dispersed into Cu powders by magnetic stirring process and then the mixed powders were consolidated by spark plasma sintering to fabricate W-CNTs/Cu composites. The CNTs/Cu composites were fabricated using the similafprocesses. The friction coefficient and mass wear loss of W-CNTs/Cu and CNTs/Cu composites were studied. The results showed that the W-CNT content, interfacial bonding situation, and applied load could influence the friction coefficient and wear loss of W-CNTs/Cu com- posites. When the W-CNT content was 1.0 wt.%, the W-CNTs/Cu composites got the minimum friction coefficient and wear loss, which were decreased by 72.1% and 47.6%, respectively, compared with pure Cu specimen. The friction coefficient and wear loss of W-CNTs/Cu composites were lower than those of CNTs/Cu composites, which was due to that the interracial bonding at （W-CNTs）-Cu interface was better than that at CNTs-Cu interface. The friction coefficient of composites did not vary obviously with increasing applied load, while the wear loss of composites increased significantly with the increase of applied load.

Evaluation of mechanical and wear properties of hybrid aluminium matrix composites

Hybrid metal matrix composites are important class of engineering materials used in automotive, aerospace and other applications because of their lower density, higher specific strength, and better physical and mechanical properties compared to pure aluminium. The mechanical and wear properties of hybrid aluminium metal matrix composites were investigated. Mica and SiC ceramic particles were incorporated into A1 356 alloy by stir-casting route. Microstructures of the samples were studied using scanning electron microscope （SEM）. The chemical composition was investigated through energy dispersive X-ray （EDX） detector. The results indicate that the better strength and hardness are achieved with A1/10SiC-3mica composites. The increase in mass fraction of mica improves the wear loss of the composites.

Influence of loading and rotation speed on Friction and Wear properties of CuAlBi Alloy

The variation of the friction coefficient of the CuAlBi alloy at different connecting loading and friction speed were investigated by using MMU-5G sliding friction-wear tester, besides, the wear mass loss of the CuAlBi alloy was measured, and the influence of loading and rotation speed on friction and wear properties of CuAlBi alloy was also discussed. The results show that the friction coefficient increase then decrease with increase of connecting loading as well as decreases with increase of friction speed, and the wear loss mass increases with increase of connecting loading and friction speed. As a result, the wear failure form of CuAlBi alloy is mainly ploughing.

Influence of graphite content on sliding wear characteristics of CNTs-Ag-G electrical contact materials

CNTs-Ag-G electrical contact composite material was prepared by means of powder metallurgical method. The influence of the graphite content on sliding wear characteristics of electrical contact levels was examined. In experiments, CNTs content was retained as 1% (mass fraction), and graphite was added at content levels of 8%, 10%, 13%, 15% and 18%, respectively. The results indicate that with the increase of graphite content, the contact resistance of electrical contacts is enhanced to a certain level then remains constant. Friction coefficient decreases gradually with the increase of graphite content. Wear mass loss decreases to the minimum value then increases. With the small content of graphite, the adhesive wear is hindered, which leads to the decrease of wear mass loss, while excessive graphite brings much more worn debris, resulting in the increase of mass loss. It is concluded that wear mass loss reaches the minimum value when the graphite mass fraction is about 13%. Compared with conventional Ag-G contact material, the wear mass loss of CNTs-Ag-G composite is much less due to the obvious increase of hardness and electrical conductivity, decline of friction surface temperature and inhibition of adhesive wear between composites and slip rings.

Effect of Fe_2B boride orientation on abrasion wear resistance of Fe-B cast alloy

The microstructures and abrasion wear resistance of directional solidification Fe-B alloy have been investigated using optical microscopy, X-ray diffraction, scanning electron microscopy and laser scanning microscopy. The results show that the microstructure of as-cast Fe-B alloy consists of ferrite, pearlite and eutectic boride. After heat treatment, the microstructure is composed of boride and martensite. The plane which is perpendicular to the boride growth direction possesses the highest hardness. In two-body abrasive wear tests, the silicon carbide abrasive can cut the boride and martensite matrix synchronously, and the wear mechanism is micro cutting mechanism. The worn surface roughness and the wear weight loss both increase with the increasing contact load. Moreover, when the boride growth direction is perpendicular to the worn surface, the highest hardness plane of the boride can effectively oppose abrasion, and the martensite matrix can surround and support borides perfectly.

Friction and Wear Behavior of GCr15 Under Multiple Movement Condition

Friction and wear of GCr15 under cross-sliding condition is tested on a ball-on-disc wear test machine. Thisresult shows that the cross-sliding of friction pair leads to different friction and wear behavior. For the condition de-scribed in this paper, the friction coefficients with ball reciprocating are smaller than that without ball reciprocating.The friction coefficients increase with the increase of reciprocating frequency.. The wear weight loss of the ball sub-jected reciprocating sliding decreases, however, the wear weight loss of disc against the reciprocating ball increases. Incross-sliding friction, the worn surfaces of the ball show crinkle appearance along the circumferential sliding traces.Delaminating of small strip debris is formed along the plowing traces on the disc worn surface. The plowing furrow onthe disc surfaces looks deeper and wider than that without reciprocating sliding. The size of wear particles fromcross-sliding wear is larger than those without reciprocating sliding.

Influence of Material Condition on the Dry Sliding Wear Behavior of Spring Steels

During the past two decades, considerable efforts have been made in the development of high performance spring steels to meet the needs for weight and savings in the automotive industry. During the service the suspension system will be subjected to different environmental conditions, at the same time it has to sustain a variety of loads acting on it. Among all the wear of spring steel plays a vital role. In this experimental analysis an attempt has been made to investigate the performance of spring steel (EN-47 / SUP 10) under the dry sliding condition. The specimen preparation and the experimentations have been carried out according to the ASTM G99 standards. The effects of tempering and cryogenic treatments on the performance of the spring steel have also been determined. The results have revealed that the material condition has got a significant influence on the performance of the spring steel. In order to analyze the percentage contribution of different wear parameter and the material condition, the DOE and ANOVA have been made. The results have shown that the load (49.205%) has shown the highest influence and the material condition has shown 22.56% of contribution on wear behavior.

A Contact Model for Establishment of Hip Joint Implant Wear Metrics

Wear is an important issue in hip implants. Excessive wear can lead to toxicity and other implant associated medical issues such as patient discomfort and decreased mobility. Since implant wear is the result of contact between surfaces of femoral head and acetabulum implant, it is important to establish a model that can address implant surface roughness interaction. A statistical contact model is developed for the interaction of femoral head and acetabulum implant in which surface roughness effects are included. The model accounts for the elastic-plastic interaction of the implant surface roughness. For this purpose femoral head and acetabulum implants are considered as macroscopically spherical surfaces containing micron-scale roughness. Approximate equations are obtained that relate the contact force to the mean surface separation explicitly. Closed form equations are obtained for hysteretic energy loss in implant using the approximate equations.

Effect of Orientation and Applied Load on Abrasive Wear Property of Brass 60:40

Wear is a continuous process in which material is degraded with every cycle. Scientists are busy in improving the wear resistance. Approximately 75% failure in components or machine parts is due to wear. The present paper investigates experimentally the effect of orientation and normal load on alloy of copper and zinc, i.e. Brass, and calculates weight loss due to wear. To do so, a multi-orientational pin-on-disc apparatus was designed and fabricated. Experiments were carried out under normal load 05-20 N, speed 2000 rpm. Results show that the with-increasing load weight loss increases at all angular positions. The loss in weight is maximum at zero degree (horizontal position) and minimum at ninety degree (vertical position) for a particular load. Maximum wear occurs when the test specimen is held at 0° angle and minimum wear occurs when the specimen is held at 90° angle for given applied load. The circumferential distance travel is constant for all positions and for all loads but still mass loss varies.

表面粗糙度对SA508 Gr.3 Cl.1钢-石墨摩擦副摩擦磨损性能的影响

采用旋转钢圆环-固定石墨圆环式端面摩擦副结构,对不同表面粗糙度(0.319,0.451,1.210,2.300,5.240μm)的SA508 Gr.3 Cl.1钢进行干摩擦磨损试验,研究了试验钢表面粗糙度对摩擦副摩擦磨损性能的影响,分析了磨损机制。结果表明:随着试验钢表面粗糙度增加,摩擦因数先减小后增大,表面粗糙度为0.451μm时最小,为5.240μm时最大;石墨的摩擦磨损质量损失整体呈增大趋势,磨损机制均以磨粒磨损为主。当表面粗糙度较低时,石墨在试验钢磨损面形成大面积光滑的转移膜,膜中碳含量较高;当表面粗糙度较高时,产生犁沟效应,石墨转移膜面积较小,膜中碳含量较少。

气囊抛光中抛光垫表面沟槽结构对轴承套圈抛光质量的影响

为研究圆柱形气囊抛光中抛光垫表面沟槽结构对GCr15轴承钢抛光质量的影响,通过Fluent软件分析沟槽结构对抛光液流速和动压力的影响,并优化沟槽结构参数,进一步开展GCr15轴承钢套圈内表面定点气囊抛光试验,研究沟槽结构对抛光垫磨损行为、材料去除率和工件表面粗糙度的影响。结果表明:V形沟槽抛光垫的抛光效果优于无沟槽、栅格形沟槽和斜沟槽抛光垫,比无沟槽抛光垫磨损量降低了42.37%,最大材料去除率提高了17.04%,表面粗糙度降低了16.32%。

镀镍FeS对铁基轴承材料摩擦磨损性能的影响

以Fe,C混合粉末为原料,FeS或镀镍FeS为固体润滑剂,通过粉末冶金工艺制备了FeS/铁基轴承材料的试样,研究镀镍FeS对试样显微组织、密度、硬度和摩擦磨损性能的影响,结果表明:FeS表面镀镍提高了FeS与基体的界面结合强度,增大了试样的密度和硬度;干摩擦条件下,含镀镍FeS试样摩擦表面形成的固体润滑膜更牢固、完整,黏着磨损减少,耐磨性提高;油润滑条件下,润滑油膜与FeS固体润滑膜可以协同润滑,提高了摩擦副间润滑膜的稳定性和承载能力,减摩耐磨性能更好。

TiN/DLC和NiN/DLC涂层的组织结构及摩擦磨损性能

采用磁控溅射沉积技术在316L不锈钢基体上分别沉积了以TiN和NiN为过渡层的类金刚石(Diamond-like carbon,DLC)涂层。采用扫描电镜、拉曼光谱仪、纳米压痕仪、划痕测试仪和摩擦磨损试验机分析了DLC涂层的表面质量、组织结构和摩擦磨损性能。结果表明:NiN/DLC涂层表面颗粒及孔洞等沉积缺陷数量多,Ni和N共同沉积作为中间过渡层时,Ni多以金属单质的形式存在于DLC和基体之间,而由于金属基体结构及Ni的存在,提高了基体和过渡层间的界面匹配性,使得NiN/DLC涂层膜基结合强度高,接合力达到14.91 N;但Ti与N共同沉积作为过渡层时,Ti和C结合形成金属碳化物存在于DLC和基体之间,这有利于涂层密度(1.929 g/cm 3)和硬度的提高;而且高硬度金属碳化物的形成也有利于涂层变形能力的改善,并利于DLC结构的非晶化及促进sp 3-C键的形成。磨擦磨损分析则表明,无论是在干摩擦、去离子水中还是弱酸(pH=5.6的HCl溶液)工况下,NiN/DLC涂层由于硬度低、组织密度低导致涂层的抗摩擦磨损能力和耐腐蚀能力差;而TiN/DLC涂层具有更低的磨擦系数和磨损量,耐磨、抗磨和耐蚀性能优异。以上实验分析说明具有更高硬度的Ti的氮化物和碳化物作为过渡层能够更好地改善DLC涂层结构和摩擦磨损性能,而Ni为过渡层能够有效提高NiN/DLC涂层的膜基结合强度,但涂层磨擦过程中容易脱落失效。

FLM-YOLOv8:一种轻量级的口罩佩戴检测算法

针对现有的口罩佩戴检测模型无法较好平衡检测精度与速度,参数量较大,漏检和误检率高等问题,提出了一种轻量级的口罩佩戴检测算法FLM-YOLOv8。使用轻量级FasterNet替换YOLOv8n的主干特征提取网络,提升网络检测速度;融合FasterNet Block改进C2f模块,降低模型计算复杂度;提出SPPF-LSKA结构,增强模型的特征表达能力和感知能力,提高网络检测精度;设计Inner-MPDIoU边界框回归损失函数,提高回归预测精度,加快收敛速度。创建标注了一个复杂多元场景下的口罩佩戴数据集,并使用马赛克数据增强,以提高网络泛化能力。实验结果表明,该算法在正确佩戴口罩、未正确佩戴口罩和未佩戴口罩目标上的mAP@0.5达到了91.3%,FPS达到了143.6,实现了更加实时准确的口罩佩戴检测。

挤压力及热处理对体育器材用7A09铝合金组织和性能的影响

采用挤压铸造工艺制备了7A09铝合金,研究了挤压力及时效工艺对7A09铝合金组织和性能的影响。结果表明:以挤压力为25、50和75 MPa的挤压铸造工艺制备的7A09铝合金铸件内无气孔、缩孔等缺陷,其显微组织比采用普通铸造工艺制备的铝合金铸件致密;挤压铸造的合金晶粒和沉淀相比普通铸造的合金的细小,随着挤压力的增大,合金的硬度和抗拉强度升高,磨损质量损失减小;经120℃时效130 min后,挤压铸造的合金的磨损质量损失比普通铸造的合金显著减小,这是由于挤压铸造合金凝固时间缩短、沉淀相密度提高、晶粒较细小和共晶组织分布较均匀从而耐磨性显著改善所致。

内圈异常二次磷化对铁路轴承性能的影响

针对某铁路轴箱用双列圆锥滚子轴承内圈异常二次磷化后轴承运行过程中出现严重发热故障的问题,进行相关试验以进一步研究内圈二次磷化导致轴承失效的机理。试验结果表明:相较于正常一次磷化,内圈二次磷化的磷化膜厚度更大,磷化腐蚀层更深,膜层附着力较弱,更易磨损脱落;二次磷化轴承经跑合试验后,内圈磷化膜短期内出现大量磨损,导致轴向游隙异常增大,进而使轴承出现比较严重的偏载现象,同时润滑脂润滑性能下降,内部摩擦发热增大,导致轴承发生严重发热故障。

惯性基准法在地铁轨道检测中的应用

地铁的使用寿命与地铁轨道的损耗状况有关,及时地发现轨道问题,并加以修复可以有效提高地铁使用寿命;为了提升城市地铁的使用寿命,研究构建了一个基于惯性基准法的地铁轨道波磨损耗检测系统;该系统以惯性基准法为核心,配合加速度计,及检测车辆,对地铁轨道的波磨损耗情况进行检测;结果显示,惯性基准法的检测标准差,总是低于弦测法的检测标准差,检测长度为400 m时,弦测法的检测标准差为0.79 mm,而惯性标准法的检测标准差为0.72 mm;基于惯性基准法的检测系统的检测结果与实际情况基本一致;研究构建的地铁轨道波磨损耗检测系统的检测成本更低,且检测精度符合实际应用需求。

固定-活动义齿在牙齿重度磨耗伴缺失治疗中的应用

目的:分析固定-活动义齿在牙齿重度磨耗伴缺失治疗中的应用效果。方法:回顾性分析2020年2月-2021年10月在笔者医院行口腔修复治疗的88例牙齿重度磨耗伴缺失患者的临床资料,按治疗方式的不同分为对照组(n=43,活动义齿修复)和研究组(n=45,固定-活动义齿修复)。修复后半年判定两组修复效果,并比较两组患者修复前及修复后半年咀嚼效能、颞下颌关节(Temporomandibularjoint,TMJ)功能、生活质量及修复满意度。结果:研究组修复效果(95.56%)明显高于对照组(81.40%)(P<0.05);修复后两组咬合力、咀嚼效率和修复前相比均明显增高(P<0.05),且研究组高于对照组(P<0.05);修复后两组Helkimo临床功能障碍指数、TMJ功能指数(Fricton指数)中的TMJ紊乱指数评分、口腔健康影响程度量表14(Oral health impact scale 14,OHIP-14)评分和修复前相比均明显降低(P<0.05),且研究组低于对照组(P<0.05);研究组患者修复满意度评分高于对照组(P<0.05)。结论:应用固定-活动义齿对牙齿重度磨耗伴缺失患者进行修复的效果较佳,可明显改善患者咀嚼效能和TMJ功能,有效提高其生活质量,并能够提升患者满意度。