The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Minhao Zhu - One of the best experts on this subject based on the ideXlab platform.
-
effect of contact pressure on torsional fretting fatigue damage of 316l austenitic stainless steel
Wear, 2017Co-Authors: Z B Cai, Jinfang Peng, Jie Liu, Minhao ZhuAbstract:Abstract Fretting is the small amplitude relative oscillatory motion between two solid contact surfaces. Many factors would make impacts on the fretting process, the body stress and contact pressure can be regarded as two major independent factors resulting in the fretting fatigue. The effects of torque and contact pressure on torsional fretting behavior of 316 L austenitic stainless steel are studied in a cylinder-on-cylinder contact configuration. The results indicate that torsional fatigue life drops rapidly due to fretting. The S-N curves of torsional fretting fatigue show a shape of “ C ”. Along with increasing the contact pressures, the fretting fatigue life decreases and enters to a platform area. The variety law of friction coefficient under different contact pressures is obtained. Both fatigue fracture and fretting scar are analyzed with SEM, EDX, XPS and three-dimensional white light interferometer (3D). The study shows that the torsional fretting fatigue is influenced by fretting running behavior. Meanwhile, the depth of crack initiation position would also be affected by contact pressure. In this paper, we proposed the failure mechanisms of the fretting zone, including plastic deformation, delamination, plow and Oxidative Wear.
-
effect of nitrogen ion implantation dose on torsional fretting Wear behavior of titanium and its alloy
Transactions of Nonferrous Metals Society of China, 2017Co-Authors: L I Zhengyang, Zhenbing Cai, W U Yanping, Minhao ZhuAbstract:Abstract Various doses of nitrogen ions were implanted into the surface of pure titanium, Ti6Al7Nb and Ti6Al4V, by plasma immersion ion implantation. Torsional fretting Wear tests involving flat specimens of no-treated and treated titanium, as well as its alloys, against a ZrO 2 ball contact were performed on a torsional fretting Wear test rig using a simulated physiological medium of serum solution. The treated surfaces were characterized, and the effect of implantation dose on torsional fretting behavior was discussed in detail. The results showed that the torsional fretting running and damage behavior of titanium and its alloys were strongly dependent on the dose of the implanted nitrogen ions and the angular displacement amplitude. The torsional fretting running boundary moved to smaller angular displacement amplitude, and the central light damage zone decreased, as the ion dose increased. The Wear mechanisms of titanium and its alloys were Oxidative Wear, abrasive Wear and delamination, with abrasive Wear as the most common mechanism of the ion implantation layers.
-
torsional fretting Wear behavior of bonded mos2 solid lubricant coatings
Tribology Transactions, 2015Co-Authors: J Luo, Jinfang Peng, Z B Cai, Minhao ZhuAbstract:The effects of applying a bonded MoS2 solid lubricant to a 1050 steel substrate were investigated using a torsional fretting Wear apparatus. Tests were conducted under a normal load of 50 N with angular displacement amplitudes ranging from 0.1 to 5°. Wear scars were examined using scanning electron microscopy, energy-dispersive X-ray spectrometry, optical microscopy, and surface profilometry. The MoS2 coating exhibited different torsional fretting regimes than those of the substrate. Fretting regimes of the coating were primarily in the partial slip regime (PSR) and the slip regime (SR) with no mixed fretting regime. The width of the PSR narrowed. Due to the lubricating effects of the coating, the friction torque was consistently lower than that of the substrate. The damage to the coating in the PSR was very slight, and its granular structure remained even after 1,000 cycles. The damage mechanism to the SR coating was a combination of abrasive Wear, Oxidative Wear, and delamination. The MoS2 coating had p...
-
torsional fretting Wear of a biomedical ti6al7nb alloy for nitrogen ion implantation in bovine serum
Tribology International, 2013Co-Authors: Zhenbing Cai, Guangan Zhang, Yongkui Zhu, Mingxue Shen, Liping Wang, Minhao ZhuAbstract:Abstract Ti6Al7Nb is a high-strength titanium alloy used in replacement hip joints that possesses the excellent biocompatibility necessary for surgical implants. Ti6Al7Nb treated with nitrogen gas (N 2 ) plasma immersion ion implantation–deposition (PIII–D) was investigated. Torsional fretting Wear tests of untreated and nitrogen-ion-implanted Ti6Al7Nb alloys against a Zr 2 O ball (diameter 25.2 mm) were carried out under simulated physiological conditions (serum solution) in a torsional fretting Wear test rig. Based on the analyses of the frictional kinetics behavior, the observation of 3D profiles, SEM morphologies and surface composition analyses, the damage characteristics of the surface modification layer and its substrate are discussed in detail. The influence of nitrogen ion density on the implantation and torsional angular displacement amplitudes were investigated. The results indicated that ion implantation layering can improve resistance to torsional fretting Wear and thus has wide potential application for the prevention of torsional fretting damage in artificial implants. The damage mechanism prevented by the ion implantation layer on the Ti6Al7Nb alloy is a combination of Oxidative Wear, delamination and abrasive Wear. An increase in ion implantation concentration inhibited detachment by delamination.
-
tribological behavior of polymethyl methacrylate against different counter bodies induced by torsional fretting Wear
Wear, 2011Co-Authors: Zhenbing Cai, Minhao Zhu, Shanshan Gao, Xiuzhou Lin, Juan LiuAbstract:Abstract A torsional Wear and friction simulator with a ball on flat polymer was developed to analyze the tribological behavior of hip joints. Wear tests of polymethyl methacrylate (PMMA) against GCr15 (AISI 52100) steel and PMMA molecules (both with diameters of 40 mm) were conducted. Based on the analysis of frictional kinetics behaviors, and observations of three-dimensional (3D) profiles and SEM morphologies, the damage characteristics of PMMA were discussed in detail. With the increases of angular displacement amplitude, three types of torque/angular displacement amplitude ( T – θ ) curves (i.e., linear, parallelogram, and elliptical loops) were observed during the process of torsional fretting Wear. In each of these loops, PMMA ran in a partial slip regime (PSR), mixed slip regime (MSR), and gross slip regime (SR), respectively. Compared to the PMMA/PMMA (P/P) counter-pairs, the boundary of the fretting regime of PMMA/GCr15 (P/G) counter-pairs shifted toward the direction of lower angular displacement amplitudes. The Wear mechanisms of P/G counter-pairs included fatigue Wear, Oxidative Wear, and adhesive Wear; however, only abrasive Wear was found for the P/P counter-pairs.
S V Dobatkin - One of the best experts on this subject based on the ideXlab platform.
-
microstructural mechanical and tribological properties of ultrafine grained cu cr zr alloy processed by high pressure torsion
Journal of Alloys and Compounds, 2020Co-Authors: G Purcek, H Yanar, M Demirtas, D V Shangina, N R Bochvar, S V DobatkinAbstract:Abstract The effect of temperature on tribological properties of coarse grained (CG) and ultrafine-grained (UFG) Cu–Cr–Zr alloy processed via high pressure torsion (HPT) was investigated. Dominant Wear mechanism depends on both temperature and microstructure of the alloy. Adhesive, abrasive and Oxidative Wear mechanisms are operative in all samples at room temperature. Adhesive Wear mechanism is also operative at 200 °C. Oxidative Wear is found to be another Wear mechanism at that temperature. The breakdown of oxide layers generates spherical Wear particles which activate another Wear mechanism of three-body abrasive Wear. Excessive oxide layer formation is observed at 400 °C. Thick oxide layer covers the worn surface and provides a Wear-protective load-bearing layer which brings about high Wear resistance at 400 °C especially for the CG samples.
M X Wei - One of the best experts on this subject based on the ideXlab platform.
-
selection of heat treatment process and Wear mechanism of high Wear resistant cast hot forging die steel
Journal of Iron and Steel Research International, 2012Co-Authors: M X Wei, Shuqi Wang, X H Cui, La Wang, K M CheAbstract:Dry sliding Wear tests of a Cr-Mo-V cast hot-forging die steel was carried out within a load range of 50–300 N at 400 °C by a pin-on-disc high-temperature Wear machine. The effect of heat treatment process on Wear resistance was systematically studied in order to select heat treatment processes of the steel with high Wear resistance. The morphology, structure and composition were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS); Wear mechanism was also discussed. Tribo-oxide layer was found to form on worn surfaces to reduce Wear under low loads, but appear inside the matrix to increase Wear under high loads. The tribo-oxides were mainly consisted of Fe3O4 and Fe2O3, FeO only appeared under a high load. Oxidative mild Wear, transition of mild-severe Wear in Oxidative Wear and extrusive Wear took turns to operate with increasing the load. The Wear resistance strongly depended on the selection of heat treatment processes or microstructures. It was found that bainite presented a better Wear resistance than martensite plus bainite duplex structure, martensite structure was of the poorest Wear resistance. The Wear resistance increased with increasing austenizing temperature in the range of 920 to 1120 °C, then decreased at up to 1 220 °C. As for tempering temperature and microstructure, the Wear resistance increased in following order: 700 °C (tempered sorbite), 200 °C (tempered martensite), 440 to 650 °C (tempered troostite). An appropriate combination of hardness, toughness, microstructural thermal stability was required for a good Wear resistance in high-temperature Wear. The optimized heat treatment process was suggested for the cast hot-forging steel to be austenized at 1020 to 1120 °C, quenched in oil, then tempered at 440 to 650 °C for 2 h.
-
relations between Oxidative Wear and cr content of steels
Wear, 2011Co-Authors: M X Wei, S Q Wang, K M Chen, X H CuiAbstract:Abstract Dry sliding Wear tests at 25–400 °C were performed for 45, 4Cr5MoSiV1 and 3Cr13 steels; the relations between Oxidative Wear and Cr content of steels were explored. The low and medium-Cr steels had a substantially lower Wear rate and increasing tendency than the high-Cr steel at 25–200 °C, but the contrary case occurred at 400 °C. With an increase of ambient temperature, the Wear rate of the low and medium-Cr steels first decreased, then increased and reached the lowest value at 200 °C, while the Wear rate of the high-Cr steel decreased monotonously with the lowest value at 400 °C. At 25 °C, trace tribo-oxides reduced Wear to some extent in adhesive-dominated Wear for the low and medium-Cr steels. At 200 °C, a small amount of tribo-oxides formed and reached a thickness of 10 μm on contacting asperities in the low and medium-Cr steels, thus Oxidative mild Wear prevailed. At 400 °C, a great amount of tribo-oxides appeared in the low and medium-Cr steels; unexpectedly, the high-Cr steel had more tribo-oxides than the low or medium-Cr steels in some cases. Its high Wear resistance may be attributed to Cr-strengthened adhesion power of tribo-oxides and matrix.
-
analysis for Wear behaviors of Oxidative Wear
Tribology Letters, 2011Co-Authors: M X Wei, S Q Wang, K M Chen, X H CuiAbstract:Sliding Wear tests were performed for H13 steel and a cast steel under atmospheric conditions of 25, 200, and 400°C. XRD results identify that Oxidative Wear prevailed for the steels during sliding at 200–400°C. However, the Oxidative Wear at 200°C presented entirely different Wear behaviors from the one at 400°C. With an increase of load, the Oxidative Wear at 200°C exhibited slowly increased and lower Wear rates, despite relatively less tribo-oxides. On the contrary, although there were more tribo-oxides, the Oxidative Wear at 400°C presented rapidly increased and higher Wear rates. The former Oxidative Wear could be classified into mild Wear; the latter one fell beyond mild Wear. The two types of Oxidative Wear universally existed; their discrepancies were mainly attributed not to the tribo-oxides, but to the extent of softening and deformation of substrate. Hence, we suggested that the two types of Oxidative Wear should be distinguished in the coming research, and were termed Oxidative mild Wear and Oxidative Wear, respectively.
-
effects of the tribo oxide and matrix on dry sliding Wear characteristics and mechanisms of a cast steel
Wear, 2010Co-Authors: S Q Wang, M X Wei, Y T ZhaoAbstract:Abstract The dry sliding Wear tests were performed at the ambient temperature range of 25–400 °C on a pin-on-disc configuration for a cast steel with various tempered microstructures. The effects of the tribo-oxide and matrix on the dry sliding Wear behaviors were investigated and Wear mechanisms were explored. The Wear behaviors and Wear mechanisms of the steel were found to be closely related with the tribo-oxide and matrix. With an increase in the ambient temperature and load, the amount of tribo-oxides increased, but the subsurface matrix softened for high-hardness microstructure and workhardened for low-hardness microstructure. Tribo-oxides reduced Wear on a prerequisite that matrix retained certain strength to support tribo-oxide layer, otherwise they did not provide the protection against Wear. For the tempered martensite and tempered troostite, trace or a small amount of tribo-oxides would relatively reduce the Wear rate of adhesive Wear. A small amount of tribo-oxides formed at 200 °C totally prevented intermetallic contact, mild Oxidative Wear prevailed. However, as the matrix was soft (tempered sorbite) or softened at elevated-temperature, tribo-oxides could not reduce Wear; the Oxidative Wear was beyond mild Oxidative Wear, even the plastic extrusion Wear prevailed.
-
Transition of elevated-temperature Wear mechanisms and the Oxidative delamination Wear in hot-working die steels
Tribology International, 2010Co-Authors: Shuang Wang, M X Wei, Fajun Wang, Yan ZhaoAbstract:Abstract Dry sliding Wear tests of H13 and H21 steels were performed at 400 °C. The Wear mechanisms and their transitions were studied, and an Oxidative delamination Wear was suggested. A mild Oxidative Wear prevailed with oxide fatigue delamination under less than 3.54 MPa. Under 3.54–5.31 MPa, the Oxidative Wear prevailed with oxide fatigue delamination and the Oxidative delamination Wear. As the pressure surpassed 5.31 MPa, a severe Wear prevailed with the Oxidative delamination Wear and the plastic extrusion. The Oxidative delamination Wear meant that the delamination occurred inside the matrix underneath tribo-oxides with long-ditch delamination and belt-like Wear debris.
S Q Wang - One of the best experts on this subject based on the ideXlab platform.
-
mild to severe Wear transition and transition region of Oxidative Wear in steels
Wear, 2013Co-Authors: S Q Wang, Y T Zhao, Lei Wang, Yixiang Sun, Z R YangAbstract:Abstract Dry sliding tests for steels were performed in air under the test temperature at 400 °C and the loads of 50–250 N. The Wear behavior and characteristics were focused on to explore their general characters in severe conditions. The Wear behavior of various steels presented a common Wear regular pattern; a mild-to-severe Wear transition occurred with an increase of the load. Because Oxidative Wear prevailed, this was suggested to call the mild-to-severe Wear transition of Oxidative Wear. More importantly, a transition region in the Oxidative Wear was found to exist and corresponded to the different-extent plastic deformation of the subsurface substrate. Through reviewing the past research, the mild-to-severe Wear transition of Oxidative Wear was noticed to be a popular phenomenon in dry sliding Wear of severe conditions, particularly elevated-temperature. This transition (region) with Oxidative-Wear characteristics was considered to the essence of Wear failure in severe conditions, which was a physical and chemical process including oxidation, thermally softening and plastic deformation of worn surfaces and subsurfaces. And the Wear characteristics in the transition region were revealed.
-
characteristics of Oxidative Wear and Oxidative mildWear
Tribology International, 2013Co-Authors: Q Y Zhang, X H Cui, K M Chen, Lei Wang, S Q WangAbstract:Abstract Dry sliding tests were performed for 45, 4Cr5MoSiV1 steels and 3Cr3Mo2V cast steel at 200 and 400 °C. The Wears at 200 and 400 °C are of Oxidative Wear characteristic due to tribo-oxides formed on worn surfaces. However, the Wear at 200 °C presents different Wear behaviors and characteristics from the one at 400 °C. The Wear at 200 °C is a typical Oxidative mild Wear, but the Wear at 400 °C is beyond Oxidative mild Wear, here called Oxidative Wear. The characteristics of Oxidative mild Wear and Oxidative Wear were clarified.
-
relations between Oxidative Wear and cr content of steels
Wear, 2011Co-Authors: M X Wei, S Q Wang, K M Chen, X H CuiAbstract:Abstract Dry sliding Wear tests at 25–400 °C were performed for 45, 4Cr5MoSiV1 and 3Cr13 steels; the relations between Oxidative Wear and Cr content of steels were explored. The low and medium-Cr steels had a substantially lower Wear rate and increasing tendency than the high-Cr steel at 25–200 °C, but the contrary case occurred at 400 °C. With an increase of ambient temperature, the Wear rate of the low and medium-Cr steels first decreased, then increased and reached the lowest value at 200 °C, while the Wear rate of the high-Cr steel decreased monotonously with the lowest value at 400 °C. At 25 °C, trace tribo-oxides reduced Wear to some extent in adhesive-dominated Wear for the low and medium-Cr steels. At 200 °C, a small amount of tribo-oxides formed and reached a thickness of 10 μm on contacting asperities in the low and medium-Cr steels, thus Oxidative mild Wear prevailed. At 400 °C, a great amount of tribo-oxides appeared in the low and medium-Cr steels; unexpectedly, the high-Cr steel had more tribo-oxides than the low or medium-Cr steels in some cases. Its high Wear resistance may be attributed to Cr-strengthened adhesion power of tribo-oxides and matrix.
-
analysis for Wear behaviors of Oxidative Wear
Tribology Letters, 2011Co-Authors: M X Wei, S Q Wang, K M Chen, X H CuiAbstract:Sliding Wear tests were performed for H13 steel and a cast steel under atmospheric conditions of 25, 200, and 400°C. XRD results identify that Oxidative Wear prevailed for the steels during sliding at 200–400°C. However, the Oxidative Wear at 200°C presented entirely different Wear behaviors from the one at 400°C. With an increase of load, the Oxidative Wear at 200°C exhibited slowly increased and lower Wear rates, despite relatively less tribo-oxides. On the contrary, although there were more tribo-oxides, the Oxidative Wear at 400°C presented rapidly increased and higher Wear rates. The former Oxidative Wear could be classified into mild Wear; the latter one fell beyond mild Wear. The two types of Oxidative Wear universally existed; their discrepancies were mainly attributed not to the tribo-oxides, but to the extent of softening and deformation of substrate. Hence, we suggested that the two types of Oxidative Wear should be distinguished in the coming research, and were termed Oxidative mild Wear and Oxidative Wear, respectively.
-
effects of the tribo oxide and matrix on dry sliding Wear characteristics and mechanisms of a cast steel
Wear, 2010Co-Authors: S Q Wang, M X Wei, Y T ZhaoAbstract:Abstract The dry sliding Wear tests were performed at the ambient temperature range of 25–400 °C on a pin-on-disc configuration for a cast steel with various tempered microstructures. The effects of the tribo-oxide and matrix on the dry sliding Wear behaviors were investigated and Wear mechanisms were explored. The Wear behaviors and Wear mechanisms of the steel were found to be closely related with the tribo-oxide and matrix. With an increase in the ambient temperature and load, the amount of tribo-oxides increased, but the subsurface matrix softened for high-hardness microstructure and workhardened for low-hardness microstructure. Tribo-oxides reduced Wear on a prerequisite that matrix retained certain strength to support tribo-oxide layer, otherwise they did not provide the protection against Wear. For the tempered martensite and tempered troostite, trace or a small amount of tribo-oxides would relatively reduce the Wear rate of adhesive Wear. A small amount of tribo-oxides formed at 200 °C totally prevented intermetallic contact, mild Oxidative Wear prevailed. However, as the matrix was soft (tempered sorbite) or softened at elevated-temperature, tribo-oxides could not reduce Wear; the Oxidative Wear was beyond mild Oxidative Wear, even the plastic extrusion Wear prevailed.
G Purcek - One of the best experts on this subject based on the ideXlab platform.
-
microstructural mechanical and tribological properties of ultrafine grained cu cr zr alloy processed by high pressure torsion
Journal of Alloys and Compounds, 2020Co-Authors: G Purcek, H Yanar, M Demirtas, D V Shangina, N R Bochvar, S V DobatkinAbstract:Abstract The effect of temperature on tribological properties of coarse grained (CG) and ultrafine-grained (UFG) Cu–Cr–Zr alloy processed via high pressure torsion (HPT) was investigated. Dominant Wear mechanism depends on both temperature and microstructure of the alloy. Adhesive, abrasive and Oxidative Wear mechanisms are operative in all samples at room temperature. Adhesive Wear mechanism is also operative at 200 °C. Oxidative Wear is found to be another Wear mechanism at that temperature. The breakdown of oxide layers generates spherical Wear particles which activate another Wear mechanism of three-body abrasive Wear. Excessive oxide layer formation is observed at 400 °C. Thick oxide layer covers the worn surface and provides a Wear-protective load-bearing layer which brings about high Wear resistance at 400 °C especially for the CG samples.
-
effect of internal oxidation on Wear behavior of ultrafine grained nb zr
Acta Materialia, 2011Co-Authors: G Purcek, O Saray, F Rubitschek, Thomas Niendorf, H J Maier, I KaramanAbstract:The influence of surface modification by internal oxidation on dry sliding Wear behavior of ultrafine-grained (UFG) Nb–Zr was investigated using a pin-on-disc type tribometer. The results show that improvement in strength by grain refinement via equal-channel angular pressing/extrusion has no substantial effect on the Wear resistance of the non-oxidized UFG samples as compared to the coarse-grained material. This was attributed to the complex Wear mechanisms operating in this alloy, such as adhesion leading to smearing, tribo-chemical reactions resulting in strong Oxidative Wear and also abrasion bringing about scratches and deep grooves. However, internal oxidation by heat-treatment significantly improved the Wear resistance of Nb–Zr, especially under low to medium applied pressures due to the hardened diffusion zone with ZrO2 nanoparticles formed in the subsurface layer. Moreover, the improvement was more pronounced in the UFG material, which is attributed to increased diffusion in the UFG microstructure. When the applied pressure was increased above 0.5 MPa, however, the Wear rate increased considerably due to the elimination of the hardened subsurface layer. Still, even under high pressures, the oxidized samples demonstrated lower weight loss as compared to non-oxidized samples. Based on the investigations of the worn surfaces, it was determined that internal oxidation mostly eliminates the complex Wear mechanisms operational in the non-oxidized samples, especially under low/medium loads. Improvement in Wear properties by internal oxidation along with enhanced mechanical properties and previously demonstrated good biocompatibility and superior fatigue performance make internally oxidized UFG NbZr a promising candidate for biomedical applications in the human body.
