Selective release of less defective graphene during sliding of an incompletely reduced graphene oxide coating on steel

Xu, Shusheng,Liu, Yuzhen,Gao, Mingyu,Kang, Kyeong-Hee,Kim, Chang-Lae,Kim, Dae-Eun Elsevier 2018 Carbon Vol.134 No.-

<P><B>Abstract</B></P> <P>Recently, graphene has been gaining a lot of attention as a coating material that can be effectively utilized in reducing friction and wear of sliding components. In order to fully exploit the lubricious properties of graphene, the variation in the structure of the coating as sliding proceeds against a counter surface needs to be understood clearly. In this study, the structural evolution during sliding of an incompletely reduced graphene oxide (rGO) coating deposited on the 304 stainless steel by an electrodynamic spraying process was investigated. Experimental results showed that this coating possessed a low friction coefficient, below 0.05, under either low humidity air or dry N<SUB>2</SUB> gas condition. The micro-Raman and XPS analyses systematically revealed that less defective graphene structure was selectively released at the center region of the wear track. It was determined that the redistribution of graphene with different structures within the wear track was induced by frictional interaction at the sliding interface. Furthermore, it was determined that the degree of release of less defective graphene structure was proportional to both the applied normal force and sliding cycles.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Superior lubrication of dense/porous-coupled nanoscale C/WS₂ multilayer coating on ductile substrate

Xu, Shusheng,Liu, Yuzhen,Gao, Mingyu,Kang, Kyeong-Hee,Shin, Dong-Gap,Kim, Dae-Eun Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.476 No.-

<P><B>Abstract</B></P> <P>Sputtered carbon material has been receiving much attention as a solid lubricant coating owing to its high hardness and low coefficient of friction. However, its relatively low wear resistance performance when applied on a ductile substrate has limited its use in certain applications. In this work, a porous WS<SUB>2</SUB> sublayer was introduced to the sputtered carbon-based nanoscale multilayer coating to improve its tribological properties. The microstructural, mechanical and tribological properties of the nanoscale C/WS<SUB>2</SUB> multilayer coating were systematically investigated using various analytical techniques. Through structural optimization, a durable coating with excellent wear resistance and low frictional performances could be attained for a ductile steel substrate. The excellent toughness allowed the coating to deform with the ductile substrate without fracturing during contact sliding process. Furthermore, the first self-destruction and then recombination behaviors of dense/porous-coupled nanoscale multilayer coating as well as the selective release of carbon component to the contact interface driven by the frictional interaction aided in maintaining low friction. As a result, the nanoscale multilayer coating showed approximately 100-fold greater wear resistance than that of pure hard carbon coating on a ductile steel substrate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hard/soft-coupled nanoscale C/WS<SUB>2</SUB> multilayer coating was constructed by sputtering. </LI> <LI> The multilayer coating exhibited excellent synchronized deformation with the ductile steel substrate. </LI> <LI> Multilayer coating on ductile steel showed 100-fold longer wear life than that of a stiff C coating. </LI> <LI> The rearranged coating on the formed deep wear track resulted in improved lubrication performance. </LI> <LI> That provided a novel way to develop lubricant protection layer on ductile material surface </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Investigating the Wear Mechanisms and Tribochemical Reactions of W-Based Coatings

Yuzhen Liu,Shusheng Xu 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1

An automatic 3D CAD model errors detection method of aircraft structural part for NC machining

Huang, Bo,Xu, Changhong,Huang, Rui,Zhang, Shusheng Society for Computational Design and Engineering 2015 Journal of computational design and engineering Vol.2 No.4

Feature-based NC machining, which requires high quality of 3D CAD model, is widely used in machining aircraft structural part. However, there has been little research on how to automatically detect the CAD model errors. As a result, the user has to manually check the errors with great effort before NC programming. This paper proposes an automatic CAD model errors detection approach for aircraft structural part. First, the base faces are identified based on the reference directions corresponding to machining coordinate systems. Then, the CAD models are partitioned into multiple local regions based on the base faces. Finally, the CAD model error types are evaluated based on the heuristic rules. A prototype system based on CATIA has been developed to verify the effectiveness of the proposed approach.

Study on Electroconductive Tribological Properties of Ag-based Composite Coating

Yuzhen Liu,Mingyu Gao,Shusheng Xu,김대은 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.8

Electrical contacts are widely utilized in numerous engineering applications that require high reliability. However, fretting wear due to repeated contact may lead to increased electrical contact resistance that can cause failure of the electrical system. Herein, an Ag-based coating was prepared by an electroless co-deposition technique in order to improve the electroconductive properties under fretting conditions. By carefully controlling the deposition time, a relatively smooth and continuous Ag coating could be obtained. The structure of the coating was analyzed using X-ray diffraction, 3D confocal microscopy, and scanning electron microscopy techniques. The electroconductive tribological properties of the coating were assessed using a custom-built fretting tester. The Ag coating possessed good crystallinity and exhibited improved electroconductive properties compared with the Ni interlayer deposited on a steel substrate. The high temperature of the contact zone generated by friction contributed to the reduced electric resistance. Furthermore, incorporation of graphene as a dopant could improve the coating wear resistance, resulting in more reliable electroconductive properties in the fretting condition. The wear mechanism of the coating was also investigated through wear track analysis. The experimental results are expected to aid in understanding the electroconductive tribological properties of Ag coatings used in electrical contact applications.

Exploring the Impact of Surface Roughness on Tribological Properties at Micro and Macro Scales

Chen Wang,Wenli Wang,Kai Le,Shusheng Xu,Weimin Liu 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1

The Significantly Enhanced Mechanical and Tribological Performances of the Dual Plasma Nitrided and PVD Coated Ti6Al4V Alloy

Jiaqiang Yang,Kai Le,Hui Chen,Xu Zhao,Xiaodong Xie,Yong Luo,Shusheng Xu,Weiming Liu 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.4

In this work, plasma pre-nitriding technique has been employed to enhance the bearing capacity for the TiN coating deposited on Ti6Al4V alloy by magnetron sputtering. The composition, morphology and mechanical property of the as-prepared samples were studied by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), Vickers micro-hardness tester and nanoindentater. The tribological properties are investigated using a rotary tribometer under dry sliding and oil lubrication, and the mechanism was also discussed in details. The results show that the plasma nitriding treatment produced a nitrided layer with thickness of 85 μm on the surface of Ti6Al4V alloy, which significantly enhanced the mechanical properties. Therefore, the as-prepared TiN coated sample with plasma pre-nitriding treatment exhibit more excellent mechanical properties possessing the maximum hardness values (26 GPa) and exceptional load bearing capacity (74 N) compared to single TiN-coated Ti6Al4V. Moreover, the tribological properties of sample with plasma pre-nitriding treatment was also significantly improved, which was attributed to the synergistic effect of the superior bearing performance of nitriding layer and the high hardness of TiN coating. Additionally, wear mechanisms were discussed in terms of wear track morphology after sliding test.

Acute Effects of Transforming Growth Factor-β1 on Neuronal Excitability and Involvement in the Pain of Rats with Chronic Pancreatitis

( Xiaoyu Zhang ),( Hang Zheng ),( Hong-yan Zhu ),( Shufen Hu ),( Shusheng Wang ),( Xinghong Jiang ),( Guang-yin Xu ) 대한소화기기능성질환·운동학회 2016 Journal of Neurogastroenterology and Motility (JNM Vol.22 No.2

Background/Aims This study was to investigate whether transforming growth factor-β1 (TGF-β1) plays a role in hyperalgesia in chronic pancreatitis (CP) and the underlying mechanisms. Methods CP was induced in male adult rats by intraductal injection of trinitrobenzene sulfonic acid (TNBS). Abdominal hyperalgesia was assessed by referred somatic behaviors to mechanical stimulation of rat abdomen. Dil dye injected into the pancreas was used to label pancreas-specific dorsal root ganglion (DRG) neurons. Whole cell patch clamp recordings and calcium imaging were performed to examine the effect of TGF-β1 on acutely isolated pancreas-specific DRG neurons. Western blot analysis was carried out to measure the expression of TGF-β1 and its receptors. Results TNBS injection significantly upregulated expression of TGF-β1 in the pancreas and DRGs, and TGF-β1 receptors in DRGs (T9-T13) in CP rats. Intrathecal injection of TGF-β receptor I antagonist SB431542 attenuated abdominal hyperalgesia in CP rats. TGF-β1 application depolarized the membrane potential and caused firing activity of DRG neurons. TGF-β1 application also reduced rheobase, hyperpolarized action potential threshold, and increased numbers of action potentials evoked by current injection of pancreas-specific DRG neurons. TGF-β1 application also increased the concentration of intracellular calcium of DRG neurons, which was inhibited by SB431542. Furthermore, intrathecal injection of TGF-β1 produced abdominal hyperalgesia in healthy rats. Conclusions These results suggest that TGF-β1 enhances neuronal excitability and increases the concentration of intracellular calcium. TGF-β1 and its receptors are involved in abdominal hyperalgesia in CP. This and future study might identify a potentially novel target for the treatment of abdominal pain in CP. (J Neurogastroenterol Motil 2016;22:333-343)

Vertically constructed monolithic electrodes for sodium ion batteries: toward low tortuosity and high energy density

Li, Ping,Wang, Yanan,Jeong, Jong Yeob,Gao, Xiaoming,Zhang, Kan,Neville, Anne,Xu, Shusheng,Park, Jong Hyeok The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.45

<P>Nanomaterials for battery applications are strongly appealing to the industrial community, yet conventional electrode fabrication by employing a slurry paste restricts the potential performances of nanoengineered materials, particularly with commercial-level thickness and high mass loading. Here, physical vapor deposition (PVD) prepared monolithic electrodes composed of 40 μm-thick anisotropic WS2 vertical arrays on Al foil with a mass loading of 17.5 mg cm<SUP>−2</SUP>, and several sparsely inserted nanometre-thick carbon layers are reported. The monolithic anode shows an ultra-fast Na-ion diffusivity of 2.05 × 10<SUP>−10</SUP> cm<SUP>2</SUP> s<SUP>−1</SUP>, which is two orders of magnitude faster than that of the anode prepared from a slurry paste. As a sodium-ion battery (SIB) anode, the monolithic electrode achieves prominent areal and volumetric capacities of 5.57 mA h cm<SUP>−2</SUP> and 1.39 A h cm<SUP>−3</SUP>, respectively, at a current density of 100 mA g<SUP>−1</SUP> with less than 20% decay during 300 cycles. Furthermore, a SIB full cell composed of the monolithic anode and a Na2V3(PO4)3/C cathode can provide a reversible capacity around 125 mA h g<SUP>−1</SUP> at 2C with an output voltage of 1.77 V, which demonstrates its potential for further development.</P>