The Relationship Between Near-Surface Mechanical Properties, Loading Rate And Surface Chemistry

1997 ◽  
Vol 505 ◽  
Author(s):  
A. B. Mann ◽  
P. C. Searson ◽  
J. B. Pethica ◽  
T. P. Weihs
Keyword(s):  
Mechanical Properties ◽  
Surface Chemistry ◽  
Tribological Properties ◽  
Mechanical Response ◽  
Loading Rate ◽  
Atomic Scale ◽  
Initial Contact ◽  
Surface Films ◽  
Near Surface ◽  
Mechanical And Tribological Properties

ABSTRACTThe presence of thin surface films and adsorbate layers on both metals and ceramics can cause dramatic changes in the mechanical response of the material. A similar, related, variation in tribological properties has also been observed. Though the importance of surface effects is well known and widely documented, the exact physical and chemical mechanisms that are operating remain poorly understood. The development of point probe techniques now permits the examination of mechanical and tribological properties on the same length scale as the surface films. Recently, the utilization of these testing techniques has provided a clear insight into the mechanical processes which are operating on the atomic scale. The nanoindentation results presented here show that the mechanical deformation of an individual nano-contact is a highly dynamic phenomena in which the tip-momentum on contact, as well as the loading rate during the indentation, dictate the observed mechanical properties of the material. These results indicate that the initiation of plastic deformation is dependent on the stability of atomic-size surface asperities which can be deformed irreversibly by the high stresses generated during the initial contact. Additionally, the generation of dislocations and the presence of discontinuities in the loading curve are shown to depend upon the loading rate. More significantly, it has been found that modifying the surface chemistry can cause dramatic changes in both the mode of deformation and the time-dependence of nano-scale mechanical properties. The principal conclusion that can be drawn is that the high stresses which operate over short distances make time and temperature dependent phenomena, such as diffusion and the dissipation of energy via phonons, of vital importance in determining the near-surface mechanical properties of a material. Such effects are further magnified in tribological processes where normal and tangential loading of the surface leads to the repeated making and breaking of nano-asperity contacts.

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.

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.

Thermal, mechanical, and tribological properties of short carbon fibers/PEEK composites

2017 ◽  
Vol 30 (6) ◽  
pp. 657-666 ◽  
Author(s):  
Fangfang Li ◽  
Ying Hu ◽  
Xiaochen Hou ◽  
Xiyu Hu ◽  
Dong Jiang
Keyword(s):  
Mechanical Properties ◽  
Carbon Fibers ◽  
Tribological Properties ◽  
Mechanical And Tribological Properties ◽  
Lower Viscosity ◽  
Ether Ether Ketone ◽  
Poly Ether Ether Ketone ◽  
The Coefficient Of Friction ◽  
Worn Surface ◽  
Short Carbon

In this work, the effect of thermal, mechanical, and tribological properties of the blending system of different contents of short carbon fibers (SCFs) on different-viscosity poly-ether-ether-ketone (PEEK) was reported. The composites were manufactured using injection molding technique. Mechanical and tribological properties were measured by the tensile strength, the flexural strength, the coefficient of friction, and the wear rate. The results showed that the wear resistance and mechanical properties of the PEEK with the lower viscosity appeared on a more outstanding level, and experimental results showed that PEEK composites with added 10 wt% SCFs were optimal about the tribological behaviors and mechanical properties of the composites. Furthermore, based on scanning electron microscope inspections, the situation of the friction and worn surface of the material was explained.

ANALYSIS OF TRIBOLOGICAL PROPERTIES OF SELECTED PTFE-BASED POLYMER COMPOSITES IN A SLIDING INTERACTION WITH ALUMINIUM OXIDE (Al2O3)

Tribologia ◽  
2018 ◽  
Vol 280 (4) ◽  
pp. 107-112 ◽  
Author(s):  
Władysław SKONECZNY ◽  
Sławomir KAPTACZ ◽  
Adrian BARYLSKI ◽  
Tomasz KMITA
Keyword(s):  
Mechanical Properties ◽  
Service Life ◽  
Polymer Composites ◽  
Tribological Properties ◽  
Mechanical Parameters ◽  
Reciprocating Motion ◽  
Graphite Content ◽  
Mechanical And Tribological Properties ◽  
Ptfe Composite ◽  
Bronze Powder

The paper presents the microstructure and mechanical and tribological properties of polymer composites based on polytetrafluoroethylene (PTFE) intended for use in friction couples where reciprocating motion is performed, e.g., in compressors or actuators. Micromechanical tests carried out using the Oliver-Pharr method showed that the PTFE composite with a 40% bronze content (T8B) had the most advantageous mechanical properties (hardness H, Young’s modulus E). In turn, tribological tests that were conducted using a ballon- disc tester in the linear (reciprocating) motion showed that the polytetrafluoroethylene composite with a mixture of 25% bronze powder and 15% graphite (T4GM) had the lowest tribological wear. The tribological properties of composite T5W with 25% graphite content were not much worse. Despite the most favourable mechanical parameters, the tribological wear of composites T8B and PTFE with glassy carbon (T3Ws) was nearly twice higher due to the absence of grease formed by a graphite filling. The results show that the use of composites containing a bronze-graphite filling improves the service life of lubricant-free friction couples that perform reciprocating motion.

scholarly journals THE EFFECT OF LOAD ON THE TRIBOLOGICAL PROPERTIES OF MAGNESIUM ALLOY WE54 AFTER PRECIPITATION HARDENING

Tribologia ◽  
2017 ◽  
pp. 11-15
Author(s):  
Adrian BARYLSKI ◽  
Krzysztof ANIOŁEK ◽  
Marian KUPKA ◽  
Michał DWORAK
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Tribological Properties ◽  
Precipitation Hardening ◽  
Treatment Time ◽  
Ageing Time ◽  
Mechanical Tests ◽  
Linear Wear ◽  
Direct Influence ◽  
Mechanical And Tribological Properties

The paper presents the effect of precipitation hardening on the mechanical and tribological properties of magnesium alloy WE54. Mechanical tests have shown that the hardness and Young’s modulus of the alloy increased as the ageing time became longer. Improvement of the mechanical properties had a direct influence on the tribological properties. Tribological tests were performed on a ball-on-disk tribometer, applying variable loads of 2, 5, and 10 N. In the tests, a more than fourfold decrease in the specific wear rate, a threefold reduction in the linear wear, and a ca. 20% reduction of the friction coefficient were observed. The best results were obtained for ageing time of 24 h. The extension of the heat treatment time to 48h caused overageing of the alloy, which resulted in the deterioration of its mechanical and tribological properties.

scholarly journals Nanocharacterization of Dental Materials by Atomic Force Microscopy and Their Thermal Degradation Evaluation

2021 ◽  
Vol 6 (1) ◽  
pp. 14
Author(s):  
Marius Pustan ◽  
Corina Birleanu ◽  
Sanda Mirela Pop
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Tribological Properties ◽  
Dental Materials ◽  
Time Duration ◽  
Force Microscopy ◽  
Mechanical And Tribological Properties ◽  
Filling Materials ◽  
Atomic Force ◽  
Restorative Materials

Restorative dental materials must be produced with special characteristics because they are operating in a medium environment with different humidity and temperature. These day-to-day factors play an important role in the lifetime of such dental restorative materials. Resin composites have been by far the most successful in dental applications by meeting several stringent design requirements that are difficult to achieve with homogeneous materials, such as ceramics and metal alloys. The mechanical and tribological properties of direct restorative filling materials are crucial not only to serve and allow similarity to human enamel and dentine, but also to compare composites between them and determine the objective criteria for their selection. The objective of this research is to investigate the mechanical and tribological properties of some commercial restorative materials using the atomic force microscopy technique as a function of the operating temperature. Therefore, restorative materials are expected to replace and perform as natural tooth materials. The demand is so great that most of the time, restorative filling materials replace enamel and dentin, which have very different mechanical properties, namely hardness and elastic modulus. The scope is to estimate the lifetime of such materials starting from their nano-behaviors under nano-wear, nano-friction, nano-mechanical tests. To conclude, nanoindentation is an attractive method for measuring the mechanical behavior of small specimen volumes in dental hard materials. Using this technique, the mechanical and tribological properties of nanocomposite resins were investigated. This technique only evaluates the tribo-mechanical properties of a very shallow surface region of a specimen that may have undergone damage associated with mechanical preparation that is required to achieve a satisfactory flat sample for testing. Experimental study has been carried out with several normal loads and time-duration tests, i.e., representing several steps of severity conditions for materials under investigation.

scholarly journals A review on the mechanical properties for thin film and block structure characterised by using nanoscratch test

2019 ◽  
Vol 8 (1) ◽  
pp. 628-644
Author(s):  
Xianfeng Wang ◽  
Ping Xu ◽  
Rui Han ◽  
Jun Ren ◽  
Longyuan Li ◽  
...  
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Polymer Composite ◽  
Tribological Properties ◽  
Block Structure ◽  
Mode Selection ◽  
Deep Understanding ◽  
Single Layer ◽  
Adhesion Properties ◽  
Mechanical And Tribological Properties

AbstractThe nanoscratch test has been identified as one of the important tools for evaluating the mechanical and tribological properties of materials. This paper reviews the current researches on the nanoscratch test using to characterise the mechanical properties of three typical materials, including thin film, polymer composite and concrete, from the perspectives of the Berkovich indenter, parameter selection, mode selection, and analysis of resulting data. In addition, to provide a deep understanding on the test from different magnitude, a comparison between the microscratch test and nanoscratch test on the evaluation of tribological performance is also provided in this paper. The characterisation by nanoscratch test of two structural samples, in terms of layered film structures (thin film and coating sample) and single layer block structure (polymer composite sample and concrete samples) are also described in this paper, which aims to provides a deep understand on the evaluation the adhesion, tribological and interfacial properties of the typical materials samples by nanoscratch test. Finally, the coefficient of friction and critical load are discussed, which are two important parameters in tribological properties and adhesion properties.

Microstructure, Mechanical and Tribological Properties of the Rapidly Solidified NiAl/Cr(Mo,Dy) Hypoeutectic Alloy

2016 ◽  
Vol 849 ◽  
pp. 590-596 ◽  
Author(s):  
Li Yuan Sheng
Keyword(s):  
Mechanical Properties ◽  
Wear Rate ◽  
Rapid Solidification ◽  
Tribological Properties ◽  
Hypoeutectic Alloy ◽  
Test Results ◽  
Mechanical And Tribological Properties ◽  
Different Temperatures ◽  
Sliding Test ◽  
Rapidly Solidified

The NiAl/Cr (Mo,Dy) hypoeutectic alloy was fabricated by rapid solidification. The microstructure and mechanical properties as well as tribological properties for the alloy at different temperatures were investigated. The results revealed that the rapidly solidified NiAl/Cr (Mo,Dy) hypoeutectic alloy was composed of primary NiAl, fine NiAl/Cr (Mo) eutectic lamella, Ni5Dy phase and Cr7Ni3 precipitate. The compression test showed that the rapid solidification improved the mechanical properties of the NiAl/Cr (Mo,Dy) hypoeutectic alloy obviously. The dry sliding test results showed that alloy had excellent tribological properties at about 1073 K, which obtained wear rate of 4.9 10-14m3/m·N and friction coefficient of 0.16 μ. The excellent tribological properties at high temperature may be attributed to the continuous and intact protecting lubricant film which was composed of amorphous, Cr2O3 and Al2O3 nanoparticles. Between 700 K to 900 K, the alloy demonstrated bad tribological properties, especially the high wear rate, which may be ascribed to the softening of NiAl and Cr (Mo) phases.

scholarly journals Incorporated W Roles on Microstructure and Properties of W-C:H Films by a Hybrid Linear Ion Beam Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Peng Guo ◽  
Peiling Ke ◽  
Aiying Wang
Keyword(s):  
Mechanical Properties ◽  
Tribological Properties ◽  
Ion Beam ◽  
Carbon Matrix ◽  
Ion Source ◽  
Diamond Like Carbon ◽  
Dc Magnetron Sputtering ◽  
Cross Sectional ◽  
Mechanical And Tribological Properties ◽  
Hybrid Beams

W-incorporated diamond-like carbon (W-C:H) films were fabricated by a hybrid beams system consisting of a DC magnetron sputtering and a linear ion source. The W concentration (1.08~31.74 at.%) in the film was controlled by varying the sputtering current. The cross-sectional topography, composition, and microstructure of the W-C:H films were investigated by SEM, XPS, TEM, and Raman spectroscopy. The mechanical and tribological properties of the films as a function of W concentration were evaluated by a stress-tester, nanoindentation, and ball-on-disk tribometer, respectively. The results showed that films mainly exhibited the feature of amorphous carbon when W concentration of the films was less than 4.38 at.%, where the incorporated W atoms would be bonded with C atoms and resulted in the formation ofWC1-xnanoparticles. The W-C:H film with 4.38 at.% W concentration showed a minimum value of residual compressive stress, a higher hardness, and better tribological properties. Beyond this W concentration range, both the residual stress and mechanical properties were deteriorated due to the growth of tungsten carbide nanoparticles in the carbon matrix.

Sign in / Sign up

Export Citation Format

Share Document