Surface Scratches Research Articles

Effect of cutting parameters on the corrosion resistance of 7A04 aluminum alloy in high speed cutting

This work aims to explore the effect of cutting parameters on the corrosion resistance of 7A04 aluminum alloy in high speed cutting. First, 7A04 aluminum alloy samples are subjected to short-range solution treatment under 470 °C/1 h and 490 °C/20 min, followed by double-stage aging treatment under 120 °C/3 h + 160 °C/3 h. After heat treatment, the samples are experimentally cut at high speed for single factors to investigate how cutting parameters affect the EIS, polarization curve, and corrosion morphology of 7A04 aluminum alloy in high speed cutting. The results show that for 7A04 aluminum alloy treated by solution treatment 470 °C/1 h, cutting speed 1400–1550 m/min, cutting depth 1.5–2.0 mm and feed rate 0.10–0.12 mm/tooth can yield better corrosion resistance with larger capacitance arc radius, more positive Ecorr, smaller Icorr and R, larger Rp, and fewer corrosion products. For 7A04 aluminum alloy treated by solution treatment 490 °C/20 min, cutting speed 1550–1700 m/min, cutting depth 1.5 mm and feed rate 0.12 mm/tooth can yield better corrosion resistance with larger capacitance arc radius, more positive Ecorr, smaller Icorr and R, larger Rp, and fewer corrosion products. Machined surface with more surface scratches correspond to more corrosion products, whereas adhesive chips and pits are less relevant with corrosion products. EDS analysis reveals that the corrosion products are primarily Al(OH)3 insolubles. Under the same cutting parameters, 7A04 aluminum alloy treated by solution treatment 490 °C/20 min is more corrosion resistant.

Photo‐responsive cellulose nanocrystal modified fluorinated polyacrylate based on coumarin chemistry

AbstractPhoto‐responsive cellulose nanocrystal modified fluorinated polyacrylate was synthesized by environmentally friendly RAFT‐mediated Pickering emulsion polymerization using amphiphilic block copolymer modified cellulose nanocrystal poly(acrylic acid)‐g‐CNC‐g‐poly (hexafluorobutyl acrylate‐co‐7‐(2‐methacryloyloxyethoxy)‐4‐methylcoumarin) PAA‐g‐CNC‐g‐P (HFBA‐co‐CMA) (MCNC) as a stabilizer, and the photo‐responsive coumarin groups were introduced to endow it with self‐healing function. This paper mainly studied the effect of MCNC dosage on emulsion polymerization and latex film properties. The latex particle size and its distribution decreased as the MCNC dosage increased from 0.4 wt% to 1.0 wt%, and then increased afterwards. The mechanical property and thermal stability of latex films could be significantly improved by introducing MCNC. And the surface scratches of latex films with MCNC exceeding 0.4 wt% could be completely repaired after 7 h UV irradiation. Furthermore, the photo‐responsive cellulose nanocrystal modified fluorinated polyacrylate emulsion was applied to fabric finishing by dip‐rolling treatment. And the finished fabric had good hydrophobicity, oleophobicity and surface repair performance.

The impact of surface scratches on the corrosion behavior of nanocrystalline high entropy alloy coatings: Electrochemical experiments and first-principles study

To prolong the service life of engineering components used in aggressive environments, a TiZrHfMoW refractory high entropy alloy (RHEA) coating was prepared onto a titanium alloy substrate. Various electrochemical analytical techniques were used to evaluate the corrosion resistance of the scratched RHEA coating in a 3.5 wt.% NaCl solution. The electrochemical corrosion tests indicate that the scratched RHEA coating exhibits a higher electrochemical stability and a lower corrosion rate than the bare titanium alloy. The effects of the localized plastic deformation on the corrosion behavior for the RHEA coating was investigated. A slab model for the RHEA surface was proposed for the first-principles calculation to explored the change of the electron work function (EWF) as a function of external stress. The influence of the constituent elements in the RHEA on the mechanical properties and the electron work function was study to uncover the mechanism underlying the high scratch corrosion resistance of the RHEA coating and provide guidance for the composition design of refractory high entropy alloy.

Effects of the Transfer Method and Interfacial Adhesion on the Frictional and Wear Resistance Properties of a Graphene-Coated Polymer

Graphene is a promising candidate used to reduce friction and wear in micro- and nano-device applications owing to its superior mechanical robustness and intrinsic lubrication properties. Herein, we report the frictional and wear resistance properties of a graphene-coated polymer and how they are affected by fabrication processes. The results show that graphene deposited on a polymer substrate effectively improves both frictional and wear resistance properties, and the degree of improvement significantly depends on the graphene transfer method and interfacial adhesion between graphene and the substrate. Dry-transferred graphene showed better improvement than wet-transferred graphene, and the strong adhesion of graphene achieved by imidazole treatment aided the improvement. A combined analysis of surface morphology and scratch trace shows that the graphene transfer method and graphene adhesion dominate the structural integrity of the transferred graphene, and the graphene/substrate interfacial adhesion plays a decisive role in the improvement of both properties by suppressing the delamination of graphene from the substrate during the nanoscratch test, thereby preventing crack formation in graphene and weakening the puckering effect.

Effect of Initial Surface Scratches on the Cavitation Erosion Behavior of 316L Stainless Steel Substrates and 316L Stainless Steel Coatings

Rough surfaces have been widely considered as negative factors affecting cavitation erosion resistance. However, this study presented the opposite result. Here, 316L stainless steel substrates and the arc-sprayed 316L stainless steel coatings were subjected to a specific grinding process that introduced scratches on the surfaces. The surface hardness values of these ground specimens were measured to evaluate the influence of the grinding-induced strain hardening. The cavitation erosion performance of the specimens was evaluated. The results showed that rough surfaces with scratches could enhance the cavitation erosion resistance, particularly at the early stage of cavitation erosion. The scratches had a greater effect on the cavitation erosion resistance of the coatings than on the substrates. Moreover, rough surfaces with initial surface scratches could extend the incubation period of the 316L stainless steel substrates due to the inhibition of the plastic deformation. The SEM observation showed that the scratch structure of the coating surface inhibited the growth of cracks and the propagation of cavitation pits. This study could also serve as a reference for investigating the cavitation erosion behaviors of materials with a particular surface feature.

Determining the size of the overlapping area for image stitching in dark-field detection

Dark-field microscopic imaging system has high spatial resolution, but small image field. When an optical surface with a large-diameter is tested, the image stitching is necessary to obtain the full-aperture detection results. In this paper, Harris corner detection algorithm is used to achieve the full aperture testing result by stitching multiple detection images. According to the Shannon sampling theorem, how the size of the overlapping area influences the stitching results is analysed in detail. Combined with the spatial scale of surface defects, a method for determining the size of the overlapping area is given. The standard scratch patterns are used to simulate the stitching process. On this basis, an actual stitching processing is carried out on the detection images of surface scratches of four different spatial scales. Both the simulation and experimental results show that it is reasonable to use the scale of the smallest defect to determine the number of sampling points in the stitching area.

Tribological properties of 304 stainless steel with rainwater corrosion

Aiming at exploring the influence of rainwater corrosion on the tribological properties of 304 stainless steel, the test samples were immersed in rainwater for corrosion with 6 h, 12 h, and 18 h respectively. The morphology, element content, and wettability of them before and after rainwater corrosion were obtained by white light interferometer, scanning electron microscope, energy spectrum, and contact angle measuring instrument. Then, the hardness and tribological properties were measured by Vickers hardness tester and MWF-500 reciprocating friction and wear tester. The experimental results show that the rainwater has an obviously corrosive effect on the 304 stainless steel surfaces. With the conducting of the corrosive process, the contents of N and S elements are increased which increase the hardness value, surface roughness, and wettability of test sample surface. In this case, the interfacial tribological properties is changed. Small friction coefficient is obtained, and the quantity and depth of surface scratch is decreased in dry friction. For lubricated case, the interfacial tribological properties is improved by rainwater, and small friction coefficient is obtained for corrosive samples. But, the quantity of scratch crack is increased due to the increasing of wear particles. The dissolution of metal impurities on the sample surface leads to the deterioration of the surface morphology, and the diffusion of N and S elements on the sample surface leads to the hardening and embrittlement of the sample surface, The main contribution of this work is in providing a reference for the 304 stainless steel corrosion protection.

Self-healing polymers for surface scratch regeneration.

Recently, there has been a significant increase in academic and industrial interest in self-healing polymers (SHPs) due to their remarkable ability to regenerate scratched surfaces and materials of astronomical significance. Scientists have been inspired by the magical repairing mechanism of the living world. They transformed the fiction of self-healing into reality by designing engrossing polymeric materials that could self-repair mechanical abrasions repeatedly. As a result, the durability of the materials is remarkably improved. Thus, the idea of studying SHPs passively upholds economic and environmental sustainability. However, the critical areas of self-healing (including healing efficiency, healing mechanism, and thermo-mechanical property changes during healing) are under continuous scientific improvisation. This review highlights recent notable advances of SHPs for application in regenerating scratched surfaces with various distinctive underlying mechanisms. The primary focus of the work is aimed at discussing the impact of SHPs on scratch-healing technology. Beyond that, insights regarding scratch testing, methods of investigating polymer surfaces, wound depths, the addition of healing fillers, and the environmental conditions maintained during the healing process are reviewed thoroughly. Finally, broader future perspectives on the challenges and prospects of SHPs in healing surface scratches are discussed.

An electrothermal platform for active droplet manipulation.

The smart control of droplet transport through surface structures and external fields provides exciting opportunities in engineering fields of phase change heat transfer, biomedical chips, and energy harvesting. Here we report the wedge-shaped slippery lubricant-infused porous surface (WS-SLIPS) as an electrothermal platform for active droplet manipulation. WS-SLIPS is fabricated by infusing a wedge-shaped superhydrophobic aluminum plate with phase-changeable paraffin. While the surface wettability of WS-SLIPS can be readily and reversibly switched by the freezing-melting cycle of paraffin, the curvature gradient of the wedge-shaped substrate automatically induces an uneven Laplace pressure inside the droplet, endowing WS-SLIPS the ability to directionally transport droplets without any extra energy input. We demonstrate that WS-SLIPS features spontaneous and controllable droplet transport capability to initiate, brake, lock, and resume the directional motion of various liquid droplets including water, saturated NaCl solution, ethanol solution, and glycerol, under the control of preset DC voltage (∼12 V). In addition, the WS-SLIPS can automatically repair surface scratches or indents when heated and retain the full liquid-manipulating capability afterward. The versatile and robust droplet manipulation platform of WS-SLIPS can be further used in practical scenarios such as laboratory-on-a-chip settings, chemical analysis and microfluidic reactors, paving a new path to develop advanced interface for multifunctional droplet transport.

Thermal Stress Model of Fused Silica with Scratch Surface Irradiated by Nanosecond Laser

Thermal Stress Model of Fused Silica with Scratch Surface Irradiated by Nanosecond Laser

Numerical and Experimental Investigation of the Effects of Thin Hard Coatings on the Strength of Spur Gears

Abstract: The use of thin films to coat mechanical components is a well-established practice. The main uses concern areas in which scratch resistance, corrosion resistance, surface hardness and particular aesthetic characteristics are required. In addition to these properties, it has been demonstrated that Physical Vapor Deposition (PVD) processes bring further benefits from a structural point of view, especially as regards fatigue and contact fatigue phenomena. In this research work, predictive models have been proposed which allow to evaluate the mechanical behavior of coated components to model the initiation and propagation of cracks. Spur gears used in the automotive and motorcycle industries were examined. Therefore, advanced numerical models were developed to accurately evaluate the stress-strain state of the components under examination, both as regards the fatigue at the tooth base and for the contact fatigue on the tooth flank. The results of the numerical models were finally compared with the results of the experimental tests to verify their accuracy.

Mobile phone screen surface scratch detection based on optimized YOLOv5 model (OYm)

AbstractTo improve phone screen surface detection efficiency, an optimized YOLOv5s model (OYm) based on GhostNet(YOLOv5GHOSTs) and BottleneckCSP is proposed. For a given target sample, OYm could effectively reduce the computation of GFLOPS and detection time by optimizing the network structure. The detection results show that the mean average precision_0.5 (mAP_0.5) exceeds 95%, and the average detection rate is 16 ms. Compared with the traditional YOLOv5s model, the loss of average accuracy is ensured to be controlled within 3%, the detection frame rate of OYm is risen by 56.25%, and GFLOPS is decreased by 64.2%. The principle of OYm is explained in detail, and the proposed model is then experimentally validated.

Experimental and simulation study on braking noise characteristics and noise reduction strategies of the friction pair between the SiCp/A356 brake disc and the synthetic pad

During the braking process, abnormal noise often occurs between the friction pair of SiCp/Al composite disc and synthetic brake pad. Through 1:1 bench noise test and simulation method based on complex eigenvalue analysis, the induction mechanism, influencing factors, variation rule and noise reduction strategy of braking noise were studied. The results of MM-1000 friction reduced-scale test and simulation show that the sound pressure levels of two groups of friction pairs using SiCp/A356 composite material are lower than those of FE-928W friction pair under the same working conditions. The friction surfaces of different friction pairs show different degrees of surface scratches, material transfer and peeling, which will cause the friction pairs to have different tribological properties and contact relationships, resulting in differences in braking noise. 1:1 bench test and simulation results show that the main type of brake noise of service brake parts is brake squeal, which is induced by the braking temperature rise. Its main frequency is concentrated around 2.2 kHz, and the maximum sound pressure level can reach 110 dB(A). Braking squeal is more likely to occur when the energy input of a single brake is too large, resulting in high temperature rise of the brake parts, or when the brake temperature is kept at a high level in continuous braking for several times. The orthogonal test and the control variable method were used to study the influence law of 10 variables on the tendency of braking noise. It is found that the brake pad is the main component of the braking noise, and the friction coefficient of the friction pair and the Young's modulus have a significant effect on the tendency of braking noise. Considering the test results and simulation laws, the brake noise control strategies were proposed, such as increasing the chamfer depth of the pad friction surface, reducing the friction coefficient of the friction pair, increasing the young's modulus of the pad and controlling the brake temperature rise. In addition, compared with the original model, the instability tendency coefficient (TOI) of the new disc model established through variable selection is reduced by 81.21 %, and the brake noise tendency is obviously reduced, which verifies the effectiveness of the brake noise control strategy at the simulation level.

Percutaneous Release of the First Extensor Tendon Compartment in De Quervain's Disease by Acupotomy with US-Guidance: A Cadaveric Study.

De Quervain's disease is a painful stenosing tenosynovitis of the first dorsal compartment of the hand affecting the tendons of the abductor pollicis longus and extensor pollicis brevis. This study aimed to evaluate the safety and efficacy of percutaneous first extensor compartment releases performed on embalmed cadaveric models by acupotomy operation with or without US guidance. Percutaneous release was performed with an acupotomy on 59 wrists of cadavers; 23 wrists were operated with US guidance, and 39 wrists were operated without US guidance. Each arm was dissected and assessed regarding the amount of release as well as the extent of neurovascular and tendon injury. Anatomical structures were also observed in this study. Twenty cases (87%) were successfully released with ultrasound-assisted techniques, and 27 cases (75%) were successfully released with blind techniques. No neurovascular injury occurred in any arm, regardless of technique. No significant tendon injury was seen in any arm. Although minor surface scratches were visualized in 11 cases, they occurred in 3 cases (13.04%) with ultrasound assistance and in 8 cases (22.22%) with blind techniques. There was no statistically significant difference between the two groups in the measurement of the distance from the incision marks to the blood vessels and nerves. A fibrous septum and bony protrusions were found in the first dorsal compartment, which may be anatomical factors affecting the success of treatment. Both traditional and US-guided percutaneous release by acupotomy of the first extensor tendon compartment can be performed for all wrists. US-guided techniques can improve the success rate and reduce damage during acupotomy operations.

Nanoscale mechanism of suppression of friction and wear of the diamond substrate by graphene

Reducing friction and wear are critical for improving the properties of diamond-based devices. Especially in the field of micro/nano-electro-mechanical systems (MEMS/NEMS) and ultra-precision machining (UPM). Friction and wear have more serious impacts on material performance owing to size effects. In this study, the graphene/diamond interfacial structure was created to improve the mechanical properties of the diamond substrate. The properties of suppression of friction and wear of the diamond substrate by graphene were investigated using molecular dynamics simulations. It was found that graphene effectively suppressed the friction and wear of the diamond, reducing the occurrence of surface scratches and subsurface amorphisation. The suppression effect was more evident as the number of graphene layers increased. In addition, the mechanism of suppression of graphene was revealed based on graphene wrinkles, system energy, contact interface properties and atomic stress. The simulation results showed that graphene modified the contact pattern between the indenter and the diamond substrate, which suppressed the efficiency of energy dissipation. The in-plane elasticity of graphene absorbed part of the external load and enhanced the load-bearing capacity. The atomic stress peaks of the diamond were reduced, and the atomic stress distribution was more homogenous due to the protection of graphene. This investigation will provide theoretical support for applying graphene as a lubricating medium in diamond-based devices.

Scratch hardness as a quasi-intrinsic parameter to measure the scratch resistance of polymers

In this work four different polymers (acrylonitrile-butadiene-styrene, high-impact polystyrene, rubber-toughened polybutylene terephthalate, linear low-density polyethylene) were characterized in terms of their bulk (modulus and yield stress) and surface (scratch hardness) mechanical properties. The intrinsic time-dependence of the materials was addressed by performing DMA and compression tests at varying testing speed/frequency, exploiting time-temperature superposition and Eyring's model to obtain data at strain rates compatible with scratch experiments. The latter were performed by applying different loading histories (constant depth or load) and indenters. Scratch hardness was determined using Pelletier's model; it was demonstrated that such a parameter provides a reliable and almost intrinsic (i.e. loading history independent) evaluation of scratch resistance, seen as the resistance the material opposes to indenter penetration. The material compressive yield stress (evaluated at the strain rate relevant to scratch phenomena) was found to be the key controlling factor in determining scratch hardness. It can therefore be taken as a measure of the mechanical scratch resistance when evaluating the possible effects of variables such as material composition, crystallinity, physical ageing … Its relation with other aspects of the scratch phenomenon (in particular deformation recovery) was also explored, accounting for the specific deformation regime imposed by the indenter (transitioning from elastic to predominantly plastic).

딥러닝 기반의 반도체 패키지 다이면 스크래치 검출 방법

The purpose of this paper is to evaluate the detection capability of deep learning-based surface scratches in semiconductor package dies and to determine whether deep learning can be employed as an objective inspection tool. To achieve this aim, detection capabilities are compared and evaluated based on a conventional image processing-based appearance inspection algorithm for examining equipment operating in the semiconductor package inspection process. In this study, a ResNet, which is the widely used CNN-based deep learning model, is used. The dataset was generated by collecting images of semiconductor packages being inspected in the semiconductor package appearance inspection process, which were cropped to focus on the parts necessary for the study. Three experiments were conducted for comparison. In the first experiment, the results of each detection using the Hough transform and ResNet-50 were compared. In the second experiment, the comparison was conducted in the same environment as in the first experiment by adding over-examination images. In the third experiment, the Hough transform algorithm and ResNet-50 were further compared by learning the over-examination images. Based on the results, an objective evaluation was conducted to determine whether deep learning could be applied to image processing-based machine inspection facilities.

Effects on the Titanium Implant Surface by Different Hygiene Instrumentations: A Narrative Review.

Peri-implant disease is usually caused by the accumulation of dental biofilm around the implant, and this biofilm can irradiate the gingiva tissue, which leads to inflammation and, more severely, to a deterioration of the bone structure. There is a concern regarding the removal of biofilm from the implant surface by using different hygiene instruments. Some hygiene instruments may have some effect on the dental implant surface, resulting in roughening or damage to the implant surfaces. This study reviewed the effects of titanium implant surfaces on different hygiene instruments. A literature search was conducted from PubMed, ScienceDirect, and Scopus databases for articles published from 1992 to 2021. A total of 19 full-text papers with keywords of interest that met all the eligibility criteria were selected. Surface roughness was evaluated with a scanning electron microscope and also using a profilometer, laser scanning, scanning probe, and atomic force microscopes. A metal curette produced a roughened surface on the titanium implant, but a plastic curette did not alter the surface. Instrumentation with rubber cups left the surface unchanged and appeared to smoothen the surface, whereas the air-powder abrasive instrumentation altered the surface with the presence of micro pits and pores. A conventional metal ultrasonic scaler showed significant surface topographical changes and scratches on both titanium surfaces, as a diode laser, light-emitting diode (LED), and laser treatment did not show any alteration on the rough and smooth titanium surfaces. Thus, a non-metallic instrument such as a plastic curette, rubber cups, and novel technology including diode laser, LED, and laser treatment is appropriate and can be used for debridement on smooth and machined titanium implant surfaces as well as sandblasted and acid-etched (SLA), titanium plasma-sprayed (TPS), and resorbable blasted media (RBM) surfaces. The use of metallic instruments should be avoided, and it is not recommended.

Occurrence of Grease Lubricated Impact-Sliding Composite Wear

In industrial chain drives, the sleeve slides on the pin and impact loading occurs due to the polygon effect, while the collision between the ball and cage usually produces an impact-sliding motion in the rolling element bearings. Aiming at addressing the occurrence of surface damage caused by the impact-sliding motion, a ball–disk test rig employing optical interference technology was designed and built to realize load variation. Two kinds of commercial grease types, Klüber Centoplex 3 and Centoplex 2EP, were used in the experiments when the glass disk slides at a constant speed while the steel ball collides into them. The sliding and impact motions were controlled by PLC programming. After the experiments, the mid-section grease film distributions were measured using DIIM software. The results show that surface damage can rapidly occur even in the first working cycle, and that the phenomenon is affected by the sliding speed, maximum load, and grease consistency. When the sliding speed is low, multiple contacts of asperity peaks occur in the interior contact region and develop into adhesive wear. When the sliding speed increases, surface wear starts to occur at the side-lobe position of the elastohydrodynamic lubrication (EHL) horseshoe shape and extends with time accompanied by obvious surface scratches. The wear mechanism investigated provides valuable visible information for the further exploration of impact-sliding composite wear. It is suggested that great attention should be paid to impact-sliding wear occurring with grease lubrication since such working conditions are very common in industrial applications.

A new lightweight deep neural network for surface scratch detection.

This paper aims to develop a lightweight convolutional neural network, WearNet, to realise automatic scratch detection for components in contact sliding such as those in metal forming. To this end, a large surface scratch dataset obtained from cylinder-on-flat sliding tests was used to train the WearNet with appropriate training parameters such as learning rate, gradient algorithm and mini-batch size. A comprehensive investigation on the network response and decision mechanism was also conducted to show the capability of the developed WearNet. It was found that compared with the existing networks, WearNet can realise an excellent classification accuracy of 94.16% with a much smaller model size and faster detection speed. Besides, WearNet outperformed other state-of-the-art networks when a public image database was used for network evaluation. The application of WearNet in an embedded system further demonstrated such advantages in the detection of surface scratches in sheet metal forming processes.