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1.
Materials (Basel) ; 15(18)2022 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-36143684

RESUMO

In the pressurized water reactor nuclear power plant, 316L SS chips were captured by the support grid and continued to affect the Zr-4 cladding tube, causing the fuel rods to wear and perforate. In this work, a 60° acute angle cone of 316L SS was used to simulate the cyclic impact of debris on a Zr-4 alloy tube with different initial impact velocities and impact angles. Results showed that increasing the initial impact velocity will generate a wear debris accumulation layer with a wear-reducing effect, but also promote the extension and expansion of fatigue cracks, resulting in the delamination of Zr-4 alloy tubes. The inclination of the impact angle increases the energy loss. The energy loss rate of the 45° impact is as high as 69.68%, of which 78% is generated by the impact-sliding stage. The normal force is mainly responsible for the wear removal and plastic deformation of Zr-4 alloy tubes. Tangential forces cause severe cutting in Zr-4 alloys and pushes the resulting wear debris away from the contact surfaces.

2.
Materials (Basel) ; 15(9)2022 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-35591637

RESUMO

In this paper, laser texturing is performed on the surface of Mn-Cu and Fe-Zn damping alloys and the tribological properties of the samples with various surface weaves under dry-sliding conditions are investigated. The results show that the surface weave parameters affect the size of the contact surface and change the number of micro-convex bodies at the contact interface. This leads to changes in the tangential damping of the contact and further affects the magnitude of the friction coefficient. Additionally, the damping properties significantly affect the wear mechanism and make it more prone to adhesive wear.

3.
Materials (Basel) ; 15(8)2022 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-35454578

RESUMO

In this work, the contact force model and experiment methods were used to study the dynamic response and impact wear behavior of TP316H steel. The Flore model and the classic Hertz model were selected for comparison with the experimental results, and the model was revised according to the section parameters of the TP316H tube. The results show that there is a large difference between the models without considering the effect of structural stiffness on the impact system and the test results, whereas the revised model has a good agreement. With the rise in impact mass, the coefficient of restitution increases from 0.65 to 0.78, whereas the energy dissipation and wear volume decrease. Spalling, delamination, plastic deformation, and oxidative wear are the main impact wear mechanism of TP316H steel.

4.
Nanomaterials (Basel) ; 11(9)2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34578521

RESUMO

MoS2/C nanocomposite coatings were deposited on a 304 stainless steel plate by unbalanced magnetron sputtering from carbon and molybdenum disulfide targets, and the target current of MoS2 was varied to prepare for coating with different carbon contents. The mechanical and tribological properties of the MoS2/C nanocomposite coating with different carbon contents were studied using a low-velocity impact wear machine based on kinetic energy control, and the substrate was used as the comparison material. The atomic content ratio of Mo to S in the MoS2/C coating prepared by unbalanced magnetron sputtering was approximately 1.3. The dynamic response and damage analysis revealed that the coating exhibited good impact wear resistance. Under the same experimental conditions, the wear depth of the MoS2/C coating was lower than that of the substrate, and the coating exhibited a different dynamic response process as the carbon content increased.

5.
Materials (Basel) ; 13(15)2020 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-32751849

RESUMO

In the heat exchangers of sodium-cooled fast reactors, sodium flow can cause the tubes to vibrate, resulting in fretting wear damage due to the contact between the tubes (2.25Cr-1Mo steel) and their support plate (Gr5C12 alloy). In this work, the effects of temperature on the fretting wear behavior of a 2.25Cr-1Mo heat transfer tube on a Gr5C12 alloy rod were studied. The results showed that the coefficient of friction (COF) and wear volume increased first and then decreased with the increase in temperature. Moreover, 2.25Cr-1Mo showed great wear performance at high temperatures than at room temperature and 80 °C, because of the antifriction nature of the oxidative layer and the high hardness of the tribological transformed structure layer. As the temperature increased, material transfer and plastic deformation became increasingly obvious, but average wear depth decreased. This provides data support for the practical engineering application of 2.25Cr-1Mo steel at elevated temperatures. Wear mechanisms were found to depend modestly on temperature and largely on normal load. As temperature increases, the wear mechanism gradually changes from abrasive wear to adhesive wear.

6.
Rev Sci Instrum ; 90(9): 095103, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31575227

RESUMO

Sliding electrical contact exists in various electrical equipment. However, its performance is significantly affected by the sliding condition such as the load, electricity, and the surface state of friction pairs. In this study, a novel instrument is designed and constructed for high-frequency microforce electrical sliding friction testing. The new instrument provides a unique experimental platform that enables high-frequency reciprocating friction and microforce loading, and it has an innovative data collection system that includes a cantilever beam structure to measure the microforce. In this instrument, parameters (positive force, friction, displacement, and voltage of frictional pair) are obtained and monitored in real time. The steel sheet and nickel-plated steel wire were used as materials to conduct an experiment, and the steel sheet morphology after the experiment was observed using a light microscope. Results show that the voltage and positive load significantly influence the friction coefficient and friction wear, which is crucial in understanding friction and wear behaviors.

7.
Rev Sci Instrum ; 90(4): 045114, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31043014

RESUMO

Cam mechanism is widely applied in industry because it can help achieve various complex motions of the follower via the cam contour design. However, its performance is significantly affected by the wear condition. This study proposes a load distribution measurement instrument to assist the study on friction and wear regularities of oscillating follower cam mechanisms through obtaining the normal pressure (F) and friction force (Ff) distributions along the cam profile. In the instrument, F and Ff are automatically calculated via a MATLAB program based on the geometry and the measured rotary resistance torque and rotary angle of the cam. The latter two parameters are obtained through a static torque sensor and a rotary encoder built in servo motor in real time, respectively. An experimental test was conducted and the cam morphology after service was observed using scanning electron microscopy. Results show that the wear condition of the cam is significantly related to the corresponding F and Ff. Complex load parameters of oscillating follower cam mechanisms can be provided by this instrument, which is crucial in understanding the friction and wear behaviors of cams and finding the vulnerable position.

8.
Materials (Basel) ; 12(7)2019 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30934703

RESUMO

Organic hybrid damping materials have achieved sustainable development in recent years for superior damping properties due to the hydrogen bonding of hindered phenol. However, the aggregation and crystallization of hindered phenol in the matrix can lead to a sharp decline in material properties. Thus, a series of hindered phenol hybrid carboxylated nitrile rubber (XNBR) composites with different types and contents of hindered phenol were prepared by melt blending to study the effects of different hindered phenol on the properties of organic hybrid damping materials. A dynamic mechanical analyzer (DMA) and scanning electron microscope (SEM) were used to study the dynamic mechanical properties and cross-section morphology of composites. X-ray diffraction (XRD) was used to study the crystallization of hindered phenol. The results show that the properties of organic hybrid damping materials were affected by the structure of hindered phenol, and that hindered phenol molecules with a linear structure had better performances. The greater the number of hydrogen bonds between hindered phenol and the XNBR matrix, the more difficult it was for the hindered phenol to crystallize.

9.
Materials (Basel) ; 11(9)2018 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-30150511

RESUMO

Depleted uranium has been widely applied in nuclear energy fields. However, its poor corrosion and wear resistance restrict its applications. A titanium/titanium nitride (Ti/TiN) multilayer film was deposited on a uranium surface to improve its fretting wear resistance. Fretting wear tests were carried out using a pin-on-disc configuration. The fretting behaviors of uranium and the Ti/TiN film were investigated under different normal loads. With the normal load increasing, the mode of fretting wear gradually transformed from slip region (SR) to mixed fretting region (MFR) and then to partial slip region (PSR). It is illustrated that the normal load had an obvious effect on the fretting wear behavior. The friction coefficients of both uranium and Ti/TiN multilayer film decreased with the increase of the normal load. In SR, the main wear mechanisms were delamination and abrasion for uncoated uranium, and delamination and oxidation for uranium coated with the Ti/TiN multilayer film. Photoelectron spectroscopy (XPS) analysis also showed that the Ti/TiN coating was oxidized and formed TiO2 during fretting wear. The wear depth of naked uranium was much greater than that of coated uranium, which demonstrated that the Ti/TiN multilayer film could effectively improve the wear properties of uranium.

10.
Materials (Basel) ; 11(7)2018 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-30018270

RESUMO

Outer particle collision with certain dynamic objects is not a pure impact wear behavior; it is typically accompanied by sliding wear phenomena. This study is aimed at investigating the impact-sliding wear performance of three different TC17 titanium alloys. One was untreated, and the other two were subjected to laser shock peening (LSP) by 5 and 7 J pulse energy, respectively. The wear test was performed on a novel impact-sliding wear testing rig, which can realize multiple impact-sliding motions by changing motion parameters in the x and z directions. Present results showed that wear resistance of both treated samples improved compared with the untreated alloy. Given the increase in wear cycles, increment in wear rate of the untreated sample was constantly higher than those of the treated samples. All results can be attributed to the increase in surface hardness of the material and residual compressive stress, which was also introduced after LSP.

11.
Materials (Basel) ; 11(4)2018 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-29659484

RESUMO

A fretting wear experiment with uranium has been performed on a linear reciprocating tribometer with ball-on-disk contact. This study focused on the fretting behavior of the uranium under different atmospheres (Ar, Air (21% O2 + 78% N2), and O2) and vacuum conditions (1.05 and 1 × 10−4 Pa). Evolution of friction was assessed by coefficient of friction (COF) and friction-dissipated energy. The oxide of the wear surface was evaluated by Raman spectroscopy. The result shows that fretting wear behavior presents strong atmosphere and vacuum condition dependence. With increasing oxygen content, the COF decreases due to abrasive wear and formation of oxide film. The COF in the oxygen condition is at least 0.335, and it has a maximum wear volume of about 1.48 × 107 μm³. However, the COF in a high vacuum condition is maximum about 1.104, and the wear volume is 1.64 × 106 μm³. The COF in the low vacuum condition is very different: it firstly increased and then decreased rapidly to a steady value. It is caused by slight abrasive wear and the formation of tribofilm after thousands of cycles.

12.
J Mech Behav Biomed Mater ; 78: 116-123, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29156290

RESUMO

Study of the properties of natural biomaterials provides a reliable experimental basis for the design of biomimetic materials. The mechanical properties and impact wear behaviors of turtle shell with different soaking time were investigated on a micro-amplitude impact wear tester. The damage behavior of turtle shells with different soaking time and impact cycles were systematically analyzed, also the impact dynamics behavior was inspected during the impact wear progress. The results showed that the energy absorption and impact contact force were significantly different with varied soaking time. Under different impact cycles, the peak contact force of shell samples with same soaking time were approximate to each other in value and the values of impact contact time change in a small range. However, the damage extent of shells were distinct with varied impact cycles. It was found that impact worn scars of shells increase with impact cycles increasing. However, under the same impact cycles, energy absorption and contact time increased with the extending of soaking time, but the peak contact force decrease. Especially shell without soaking, the absorption rate is the lowest.


Assuntos
Exoesqueleto/metabolismo , Fenômenos Mecânicos , Tartarugas/anatomia & histologia , Água/metabolismo , Animais , Fenômenos Biomecânicos , Teste de Materiais
13.
RSC Adv ; 8(31): 17300-17311, 2018 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-35539239

RESUMO

To improve the dispersion of talcum powder (Talc) for polymer applications, modified nano-titania powders (TiO2) using a silane coupling agent (KH550), a titanate coupling agent (NDZ201) and sodium polyacrylate (PAAS) were well adhered to the surface of Talc with a ball milling method, thereby preparing a series of mixed Talc@TiO2 particles to realize good dispersion in carboxylated acrylonitrile-butadiene rubber (XNBR). Note that Talc@TiO2 particles modified by PAAS and NDZ201 show better colloidal dispersion in anhydrous ethanol due to organification and repulsion of charge, with original Talc and NDZ201 modified Talc@TiO2 powders as a comparison. Modified Talc@TiO2 hybrid XNBR shows good performance characteristics, including damping capacity and impact resistance, depending mainly on the excellent mechanical property of Talc, good dispersion and the high adhesive force between modified Talc@TiO2 and XNBR.

14.
PLoS One ; 12(4): e0175084, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28384200

RESUMO

The Ti/TiN multi-layer film was prepared on the depleted uranium (DU) substrate by cathodic arc ion plating equipment. The character of multi-layer film was studied by SEM, XRD and AES, revealed that the surface was composed of small compact particle and the cross-section had a multi-layer structure. The fretting wear performance under different frequencies was performed by a MFT-6000 machine with a ball-on-plate configuration. The wear morphology was analyzed by white light interferometer, OM and SEM with an EDX. The result shows the Ti/TiN multi-layer film could greatly improve the fretting wear performance compared to the DU substrate. The fretting wear running and damaged behavior are strongly dependent on the film and test frequency. The fretting region of DU substrate and Ti/TiN multi-layer under low test frequency is gross slip. With the increase of test frequency, the fretting region of Ti/TiN multi-layer change from gross slip to mixed fretting, then to partial slip.


Assuntos
Teste de Materiais , Titânio/química , Microscopia Eletrônica de Varredura , Difração de Raios X
15.
PLoS One ; 11(4): e0152143, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27054762

RESUMO

A ball-on-plate wear test was employed to investigate the effectiveness of graphene (GP) nanoparticles dispersed in a synthetic-oil-based lubricant in reducing wear. The effect by area ratio of elliptically shaped dimple textures and elevated temperatures were also explored. Pure PAO4 based oil and a mixture of this oil with 0.01 wt% GP were compared as lubricants. At pit area ratio of 5%, GP-base oil effectively reduced friction and wear, especially at 60 and 100 °C. Under pure PAO4 oil lubrication, the untextured surfaces gained low friction coefficients (COFs) and wear rates under 60 and 100 °C. With increasing laser--texture area ratio, the COF and wear rate decreased at 25 and 150 °C but increased at 60 and 100 °C. Under the GP-based oil lubrication, the textured surface with 5% area ratio achieved the lowest COF among those of the area ratios tested at all test temperatures. Meanwhile, the textured surface with 20% area ratio obtained the highest COF among those of the area ratios. With the joint action of GP and texture, the textured surface with 10% area ratio exhibited the best anti-wear performance among all of the textured surfaces at all test temperatures.


Assuntos
Grafite/química , Prótese de Quadril , Lubrificantes/química , Lubrificação/métodos , Teste de Materiais , Óleos/química , Fricção , Humanos , Estresse Mecânico , Propriedades de Superfície
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