scholarly journals Study on the Mechanical and Tribological Properties and the Mechanisms of Cr-Free Ni-Based Self-Lubricating Composites at a Wide Temperature Range

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 268 ◽  
Author(s):  
Penglin Zhang ◽  
Gaopan Zhao ◽  
Wenzhen Wang ◽  
Bin Wang ◽  
Peiying Shi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tribological Properties ◽  
Wear Mechanisms ◽  
Room Temperature ◽  
Fracture Mechanisms ◽  
Powder Metallurgy Method ◽  
Mechanical And Tribological Properties ◽  
Lubricating Film ◽  
Ag Particles ◽  
Self Lubricating Composites

A Cr-free Ni-based self-lubricating composites with MoS2 and Ag as lubricants were fabricated by the powder metallurgy method. The microstructures were examined. The mechanical properties and tribological behaviors of the composites were evaluated from room temperature to 800 °C. The fractography was observed and the fracture mechanisms were analyzed. The morphologies and the phase compositions of worn surfaces were determined and the wear mechanisms were elaborated. The results indicate that MoS2 did not completely decompose after sintering, and the NiMoAl-MoS2-Ag composite has the best tribological properties (0.22, 1.68 × 10−5) at 800 °C. The main wear mechanisms are micro-ploughing and plastic deformation. The improvement of tribological properties was attributed to the formation of the lubricating film consisting of NiO, Mo oxides, various molybdates, and Ag particles. The reactions resulting in these compositions are proposed. The mechanical properties degrade with the rise of temperature and the addition of lubricants. Both NiMoAl and NiMoAlAg alloys exhibit micro-void accumulation fracture while the composites with MoS2 reveal intergranular fracture.

scholarly journals Renovation of Crystallizer Surface Using Electrodeposited Alloy Coating to Increase High-Temperature Abrasion Resistance

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1629
Author(s):  
Janette Brezinová ◽  
Mária Hagarová ◽  
Dagmar Jakubéczyová ◽  
Gabriela Baranová ◽  
Olegas Prentkovskis
Keyword(s):  
Mechanical Properties ◽  
Tribological Properties ◽  
Abrasion Resistance ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Alloy Coating ◽  
Copper Surface ◽  
Mechanical And Tribological Properties ◽  
Electrodeposited Alloy ◽  
Ball On Disc

This paper deals with the evaluation of mechanical and tribological properties of Ni-Co galvanic coatings at elevated temperatures. The coatings were deposited on the copper surface, which in practice is the material of the crystallizer. Ni-Co coatings are manufactured to increase the abrasion resistance of the crystallizer surface at elevated operating temperatures. The microhardness (HV0.05) measurements of the coating at 400 °C were used to determine its mechanical properties. The Ball-on-Disc Test was used to determine the tribological properties of the coatings at 400 °C. The mechanical and tribological properties of Ni-Co coatings at elevated temperature were compared to the results of experiments performed at room temperature. When heated to 400 °C, HV0.05 decreased by 9.5 to 22% (depending on Co content in the coating) compared to the values that were measured at 23 °C. The change in the COF for the Ni-Co coating at 400 °C was from 0.680 to 0.750 depending on the Co amount compared to the values at 23 °C. The COF values at room temperature ranged from 0.373 to 0.451. The places with higher wt. % Co had better friction properties than the places with lower wt. % Co.

scholarly journals High-Temperature Friction and Wear Properties of NiCr/hBN Self-Lubricating Composites

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 356 ◽  
Author(s):  
Xuewei Zhu ◽  
Xiaofeng Wei ◽  
Yuxiang Huang ◽  
Fu Wang ◽  
Pengpeng Yan
Keyword(s):  
Tribological Properties ◽  
Wear Mechanism ◽  
Wear Surface ◽  
Friction And Wear ◽  
Room Temperature ◽  
Powder Metallurgy Method ◽  
Wear Properties ◽  
Dust Composition ◽  
Friction And Wear Properties ◽  
Self Lubricating Composites

NiCr/hBN self-lubricating composites with hBN solid-lubricant contents of 8%, 9%, 10%, 11%, and 12% (mass fractions) were prepared by powder-metallurgy method. Their tribological properties at room temperature and 600, 700, and 800 °C were studied. SEM and XRD were performed to analyze their wear-surface morphology and abrasive-dust composition. Results indicate that the NiCr/hBN self-lubricating composites have favorable tribological properties at room temperature and 600 °C. The optimum comprehensive friction and wear performance are achieved at 10% hBN, and the main wear mechanism is abrasive wear. At 700 and 800 °C, the friction and wear properties of NiCr/hBN self-lubricating composites obviously decline. The wear surface experiences oxidation and the spinel oxides Cr2O3, NiCr2O4, and CrBO3 are formed. The main wear mechanism becomes combined scratching and glue form of adhesive wear, leading to greatly increased wear rate for the NiCr/hBN sel-lubricating composites.

Study of Tribological Properties of MoS2/Cu-Fe Matrix Self-Lubricating Composites Prepared by Induction Sintering at Elevated Temperature

2010 ◽  
Vol 33 ◽  
pp. 458-462 ◽  
Author(s):  
Chuan Qi Fu ◽  
Zhou Wang
Keyword(s):  
Elevated Temperature ◽  
Tribological Properties ◽  
Room Temperature ◽  
Testing Machine ◽  
Solid Solution Alloy ◽  
X Ray Diffraction ◽  
Wear Properties ◽  
Mechanical And Tribological Properties ◽  
Surface Morphologies ◽  
Self Lubricating Composites

The molybdenum disulfide(MoS2)/copper(Cu)-ferrum(Fe) matrix self-lubricating composites with various amounts of MoS2 additives were prepared by induction heating sintering method combined with the alloying of the Cu-Fe matrix with various metallic elements. As the temperature was increased from room temperature to 800°C, the mechanical and tribological properties of the composites were measured using the universal testing machine and MRH-3 friction-wear tester. The phase compositions and worn surface morphologies of the composites were analyzed by means of X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Meanwhile, wear mechanisms were discussed. It was found that the mechanical and friction/wear properties of MoS2/Cu-Fe matrix self-lubricating composites were related to the induction frequencies and the contents of the MoS2 as the solid lubricant. The increased MoS2 content resulted in increased mechanical and friction/wear properties at first and then decreased subsequently. The composites with proper MoS2 contents and induction frequencies have the lower the friction coefficients and wear rate at room temperature to 800°C. Meanwhile, the self-lubricating films were mainly made up of some compositions, such as pearlite, cementite, sulphide, solid solution alloy of Mo and Fe, molybdenum oxide in elevated temperature; the wear mechanism of composites has been changed from abrasive wear to ploughing wear.

Comparison in Tribological Properties of YBa2Cu3OX/Ag and Bi2Sr2CaCu2OX/Ag Self-Lubricating Composites

2011 ◽  
Vol 291-294 ◽  
pp. 34-40
Author(s):  
Hua Tang ◽  
Wen Jing Li ◽  
Chang Sheng Li
Keyword(s):  
Friction Coefficient ◽  
Tribological Properties ◽  
Room Temperature ◽  
Superconducting Transition ◽  
Friction Test ◽  
Average Value ◽  
Structure And Morphology ◽  
Disk Friction ◽  
Pin On Disk ◽  
Self Lubricating Composites

The YBa2Cu3Ox/Ag and Bi2Sr2CaCu2Ox/Ag self-lubricating composites were prepared using powder metallurgic method. The crystal structure and morphology of the as-synthesized samples were characterized by XRD and SEM. The YBa2Cu3Ox/Ag and Bi2Sr2CaCu2Ox/Ag self-lubricating composites were found to compose of superconductor phase and Ag phase. The tribological properties from ultra-low temperature to room temperature of the composites were studied by pin-on-disk friction test. It was found that the friction coefficients of pure YBa2Cu3Ox(YBCO) and Bi2Sr2CaCu2Ox(BSCCO) were both dropped abruptly when the temperature cooled below the superconducting transition temperature. At room temperature, the friction coefficient of pure YBa2Cu3Oxis 0.68~0.95, when mixing 15wt% Ag, the friction coefficient of the sample decreased to the lowest value 0.11. The friction coefficient of pure Bi2Sr2CaCu2Ox is 0.15~0.17, When Ag content reach 10wt%, the coefficient was lowest (average value is 0.13). The addition of appropriate amount of Ag obviously improve the tribological property of YBCO, while only slightly meliorate that of BSCO. On the other hand, the YBCO/Ag composites exhibit better tribological properties than BSCCO/Ag composites at higher load under the same experimental condition.

The effect of environmental humidity/water absorption on tribo-mechanical performance of polymers and polymer composites – a review

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kawaljit Singh Randhawa ◽  
Ashwin Patel
Keyword(s):  
Mechanical Properties ◽  
Polymer Composites ◽  
Tribological Properties ◽  
Fiber Reinforced Polymer ◽  
Content Type ◽  
Wear Rates ◽  
Mechanical And Tribological Properties ◽  
Reinforced Polymer ◽  
Fiber Reinforced Polymer Composites ◽  
Water Conditions

Purpose The mechanical and tribological properties of polymers and polymer composites vary with different environmental conditions. This paper aims to review the influence of humidity/water conditions on various polymers and polymer composites' mechanical properties and tribological behaviors. Design/methodology/approach The influence of humidity and water absorption on mechanical and tribological properties of various polymers, fillers and composites has been discussed in this paper. Tensile strength, modulus, yield strength, impact strength, COF and wear rates of polymer composites are compared for different environmental conditions. The interaction between the water molecules and hydrophobic polymers is also represented. Findings Pure polymer matrices show somewhat mixed behavior in humid environments. Absorbed moisture generally plasticizes the epoxies and polyamides and lowers the tensile strength, yield strength and modulus. Wear rates of PVC generally decrease in humid environments, while for polyamides, it increases. Fillers like graphite and boron-based compounds exhibit low COF, while MoS2 particulate fillers exhibit higher COF at high humidity and water conditions. The mechanical properties of fiber-reinforced polymer composites tend to decrease as the rate of humidity increases while the wear rates of fiber-reinforced polymer composites show somewhat mixed behavior. Particulate fillers like metals and advanced ceramics reinforced polymer composites exhibit low COF and wear rates as the rate of humidity increases. Originality/value The mechanical and tribological properties of polymers and polymer composites vary with the humidity value present in the environment. In dry conditions, wear loss is determined by the hardness of the contacting surfaces, which may not effectively work for high humid environments. The tribological performance of composite constituents, i.e. matrix and fillers in humid environments, defines the overall performance of polymer composite in said environments.

Tribological Properties of Hot-Pressed SrSO4 Ceramic at Elevated Temperatures in Dry Sliding Against Alumina Ball

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Chong-Chong Mao ◽  
Yu-Feng Li
Keyword(s):  
Tribological Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Testing Temperature ◽  
Dry Sliding ◽  
Potential Candidate ◽  
Friction Behavior ◽  
Wear Rates ◽  
Brittle To Ductile Transition ◽  
Lubricating Film

SrSO4 ceramic was prepared by hot-pressed sintering and its friction behavior was investigated against the Al2O3 ball under the dry sliding condition from room temperature to 800 °C. From room temperature to 400 °C, the tribological properties of SrSO4 ceramic are quite poor with the friction coefficients of 0.65–0.83 and the wear rates of about 10−3 mm3/Nm. With the testing temperature increasing to 600 °C and 800 °C, a brittle to ductile transition of SrSO4 takes place because of the activated slip systems. The friction coefficient and wear rate of SrSO4 ceramic also obviously decrease to 0.37 and about 10−4 mm3/Nm at 800 °C. The significant improvement of the tribological properties is ascribed to the formation of a smooth and continuous SrSO4 lubricating film with excellent ductility and low shear strength at elevated temperature. SrSO4 is considered to be a potential candidate for high-temperature solid lubricant with excellent lubricity.

scholarly journals Nano/micro-mechanical and tribological characterization of Ar, C, N, and Ne ion-implanted Si

2010 ◽  
Vol 25 (5) ◽  
pp. 880-889 ◽  
Author(s):  
Zhi-Hui Xu ◽  
Young-Bae Park ◽  
Xiaodong Li
Keyword(s):  
Mechanical Properties ◽  
Tribological Properties ◽  
Crystalline Silicon ◽  
Semiconductor Industry ◽  
Damage Mechanism ◽  
Mechanical And Tribological Properties ◽  
Tribological Characterization ◽  
The Relationship ◽  
Ion Implanted

Ion implantation has been widely used to improve the mechanical and tribological properties of single crystalline silicon, an essential material for the semiconductor industry. In this study, the effects of four different ion implantations, Ar, C, N, and Ne ions, on the mechanical and tribological properties of single crystal Si were investigated at both the nanoscale and the microscale. Nanoindentation and microindentation were used to measure the mechanical properties and fracture toughness of ion-implanted Si. Nano and micro scratch and wear tests were performed to study the tribological behaviors of different ion-implanted Si. The relationship between the mechanical properties and tribological behavior and the damage mechanism of scratch and wear were also discussed.

Preparation of PEEK/MWCNTs composites with excellent mechanical and tribological properties

2018 ◽  
Vol 31 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Yingshuang Shang ◽  
Xian Wu ◽  
Yifan Liu ◽  
Zilong Jiang ◽  
Zhaoyang Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tribological Properties ◽  
Frictional Coefficient ◽  
Crystallization Rate ◽  
High Strength ◽  
Multiwalled Carbon ◽  
Structural Morphology ◽  
Mechanical And Tribological Properties ◽  
The Coefficient Of Friction ◽  
Properties Of Composites

The high strength of multiwalled carbon nanotubes (MWCNTs) indicates promising properties for industry applications to reduce frictional coefficient and improve mechanical properties, yet few researches have referred to its structural morphology on the thermal, mechanical, and tribological properties of composites. In this work, three different lengths of MWCNTs were used to prepare polyether ether ketone (PEEK) composites and investigate the effect of structural morphology of MWCNTs on the thermal, mechanical, and tribological properties of composites. Different lengths of MWCNTs endowed PEEK composites with different thermal, mechanical, and tribological properties. On thermal and mechanical properties, the incorporation of 10–30 μm length of MWCNTs increased more the effectiveness on the crystallization rate, showing a higher crystallization temperature and the best mechanical properties of the PEEK composites. On tribological properties, approximately 50 μm MWCNTs can effectively decrease adhesive wear, which is a benefit of forming a thin transfer film, thereby effectively decreasing the coefficient of friction and improving the wear resistance.

Tribological and physical properties of PTFE-NBR self-lubricating composites under water lubrication

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wei Feng ◽  
Lei Yin ◽  
Yanfeng Han ◽  
Jiaxu Wang ◽  
Ke Xiao ◽  
...  
Keyword(s):  
Physical Properties ◽  
Peer Review ◽  
Tribological Properties ◽  
Water Lubrication ◽  
Butadiene Rubber ◽  
Friction Test ◽  
Bearing Material ◽  
Content Type ◽  
Lubricating Film ◽  
Self Lubricating Composites

Purpose This paper aims to explore the possibility of converting the nitrile butadiene rubber (NBR) water-lubricated bearing material into a self-lubricating bearing material by the action of polytetrafluoroethylene (PTFE) particles and water lubrication. Design/methodology/approach A group of experimental studies was carried out on a ring-on-block friction test. The physical properties, tribological properties and interface structure of PTFE-NBR self-lubricating composites filled with different percentages of PTFE particles were investigated. Findings The experimental results indicated that the reduction in friction and wear is a result of the formation of the lubricating film on the surface of the composites. The lubricating film was formed of a large amount of PTFE particles continuously supplied under water lubrication conditions and the PTFE particles here can greatly enhance the load capacity and lubrication performance. Originality/value In this study, the tribological properties of PTFE particles added to the NBR water-lubricated bearing materials under water lubrication were investigated experimentally, and the research was carried out by a ring-on-block friction test. It is believed that this study can provide some guidance for the application of PTFE-NBR self-lubricating. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0187/

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