An Analytical Model of Mechanistic Wear of Polymers

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Sandip Panda ◽  
Mihir Sarangi ◽  
S. K. Roy Chowdhury

This paper proposes a wear model for polymers based on so-called mechanistic processes comprising both low cycle fatigue and abrasive wear mechanisms, which are prominent in polymer–metal sliding interfaces. Repeated elastic contact causes localized fatigue, whereas abrasive part is an anticipatory outcome of plastic contacts by hard metal asperities on to soft polymer surface. Further, presuming adhesive interactions in elastic–plastic contacts, asperity contact theories with necessary modifications were analyzed to assess load and separation for their subsequent use in elementary wear correlations. Both Gaussian and Weibull distributions of asperity heights were considered to include statistics of surface microgeometry. Finally, volumetric wear was written in terms of roughness parameters, material properties, and sliding distance. Validation was conducted extensively, and reliability of the formulation was achieved to a large extent. Experimental part of this work included several pin-on-disk tests using polyether ether ketone (PEEK) pins and 316L stainless steel disks. Disks with different roughness characteristics generated by polishing, turning, and milling were tested. Experimental results agreed well with predictions for the polished surface and with some deviations for other two surfaces. Further, fatigue to abrasive wear ratio was identified as an analytical tool to predict prevailing wear mechanism for polymer-metal tribo-systems. After examining the considered cases, it was both interesting and physically intuitive to observe a complete changeover in wear mechanisms following simply an alteration of roughness characteristics.

2003 ◽  
Vol 125 (2) ◽  
pp. 437-444 ◽  
Author(s):  
Dong F. Wang ◽  
Koji Kato

This is the second part of two companion papers, the first of which reported the empirical data on wear properties in carbon nitride coatings by a spherical diamond counter-face in repeated sliding contacts through in situ examination, with an emphasis on the effect of friction cycles and normal load. The second part will concentrate on wear mechanisms for the transition from “No observable wear particles” to “Wear particle generation.” The relationship between the critical number of friction cycles, Nc, and the representative plastic strain, Δεp, at asperity contact region was confirmed to follow the Manson-Coffin equation with two empirical constants, β and C. The observed generation of wear particles in carbon nitride coatings is therefore concluded to be a low cycle fatigue wear by surface flow and surface delamination in the ploughing mode. For further predicting lifespan, a simplified theoretical expression, combining the Manson-Coffin equation with the analytical solution of a proposed elastic perfectly-plastic indentation model, gives the relation between the critical number of friction cycles, Nc, and the coating thickness h, with respect to the contact pressure P, and the radius R of the asperity on the tip of the diamond pin.


2014 ◽  
Vol 604 ◽  
pp. 47-50 ◽  
Author(s):  
Marcela Petrica ◽  
Thomas Peinsitt ◽  
Ewald Badisch

In industry, core components such as crushers, miner feeder devices and impact stone breakers are exposed to heavy wear which involves mechanisms such abrasive wear and / or impact abrasion. The purpose of this work is to identify complex wear mechanisms that occur in such conditions and to correlate them with the properties of typical abrasives found in mining environments.


Wear ◽  
1996 ◽  
Vol 200 (1-2) ◽  
pp. 122-136 ◽  
Author(s):  
M.Q. Zhang ◽  
K. Friedrich ◽  
K. Batzar ◽  
P. Thomas

2010 ◽  
Vol 10 (12) ◽  
pp. 8254-8259 ◽  
Author(s):  
Oscar Olea-Mejia ◽  
Witold Brostow ◽  
Eli Buchman

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yongshui Shen ◽  
Tongjin Sun ◽  
Tao Zhu ◽  
Ying Xiong

Abstract A laser shock peening (LSP) layer, a micro-arc oxidation (MAO) coating, and an LSP/MAO composite coating were fabricated on the surface of AZ80 magnesium alloy by laser shock and micro-arc oxidation process. The ball-disc grinding method was used to perform wear test on the three treated specimens in simulated body fluids (SBF) with pH values of 4, 7.4 and 9. The morphology and element content of worn surface were investigated by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results indicated that the wear rates of the three treated specimens in three pH environment in numerical order were pH 4 > pH 7.4 > pH 9, respectively. The wear rates of the three treated specimens in the same pH environment were arranged in the order of MAO > LSP > LSP/MAO, respectively. The main wear mechanisms of the LSP specimen in pH 4 environment were fatigue wear and corrosion wear, while it were corrosion wear and adhesive wear in pH 7.4 and pH 9 environments. Abrasive wear, fatigue wear and corrosion wear were the main wear mechanisms of the MAO specimen in pH 4 environment, while abrasive wear, adhesive wear and corrosion wear were the main wear mechanisms of that in pH 7.4 and pH 9 environments. The corrosion wear resistance of the LSP/MAO specimen in SBF solution with three pH values was improved due to the synergism of LSP fine crystal layer and MAO coating.


2020 ◽  
Vol 993 ◽  
pp. 836-843
Author(s):  
Ke Guo ◽  
Zhi Qiang Zhang ◽  
Zhong Zheng Pei ◽  
Jie Xu ◽  
Yi Fan Feng

Here we developed a hot-pressed molded resin-based brake pad material reinforced by a nano sodium titanate whisker in comparison with nano potassium titanate whisker. The effect of the whiskers on the tribology behavior was investigated. Though nano sodium titanate whisker reinforced brake material showed higher porosity (+12.29% averagely) and lower hardness (-25.8% averagely) caused by the impurities, it exhibited improved ability in stabilizing the friction coefficient and enhancing 25.5%, 31.1%, 25.9% higher wear resistance, when the volume contents of whisker are 7.5%, 15% and 22.5%, respectively, compared to the nano potassium titanate whisker reinforced brake material. The wear mechanisms of the nano sodium titanate whisker reinforced brake materials were determined as embedded debris, delaminated crater, moderate layers transfer, uniform furrows, primary plateaus and secondary plateaus in similar size, indicating a main wear form of abrasive wear instead of adhesive wear.


2019 ◽  
Vol 799 ◽  
pp. 83-88
Author(s):  
Ewald Badisch ◽  
Markus Varga ◽  
Stefan J. Eder

Abrasive wear limits the lifetime of key components and wear parts used in various applications. Damage is caused by indentation of harder particles into the wearing materials and subsequent relative motion resulting in ploughing, cutting, and fracture phenomena. The wear mechanisms depend mainly on the applied materials, loading conditions, and abrasives present in the tribosystem, hence material choice is often a difficult task and requires careful evaluation. For this, a variety of laboratory abrasion tests are available of which the scratch test is discussed in this work as the most fundamental abrasive interaction. For further insight into the acting wear mechanisms and microstructural effects, large-scale molecular dynamics simulations were carried out as well as meso-/macroscopic scratch simulations with the mesh-free Material Point Method. The prediction of abrasive wear is of high relevance for industrial applications. Up to now, no general one-to-one match between field application and lab system is known. Here, a simulation-based transfer of experimentally determined wear rates via a lab-2-field approach enables the prediction of wear rates in real applications.


Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1157
Author(s):  
Andrea Garfias Bulnes ◽  
Vicente Albaladejo Fuentes ◽  
Irene Garcia Cano ◽  
Sergi Dosta

This work analyzes the differences found in hard metal coatings produced by two high velocity thermal spray techniques, namely high velocity oxy-fuel (HVOF) and high velocity air-fuel (HVAF). Additionally, the effect of the metallic matrix and ceramic composition and the original carbide grain size on coating properties is compared to the most studied standard reference material sprayed by HVOF, WC-Co. For this evaluation, the physical properties of the coatings, including feedstock characteristics, porosity, thickness, roughness, hardness, and phase composition were investigated. Several characterization methods were used for this purpose: optical microscopy (OM), scanning electronic microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), and X-ray Diffraction (XRD), among others. The final performance (abrasive wear and corrosion resistance) shown by the coatings obtained by these two methodologies was also analyzed. Thus, the abrasive wear resistance was analyzed by the rubber-wheel test, while the corrosion resistance was characterized with electrochemical methods. The characterization results obtained clearly showed that the coatings exhibit different microstructures according to feedstock powder characteristics (carbide grain size and/or composition) and the thermal spray process used for its deposition. Thus, the incorporation of WB to the cermet composition led to a high hardness coating, and the complementary hardness and toughness of the WC-Co coatings justify its better abrasion resistance. The presence of Ni on the metal matrix increases the free corrosion potential of the coating to more noble region. However, the WC-Co coatings show a lower corrosion rate and hence a higher protective performance than the rest of the coatings.


2011 ◽  
Vol 311-313 ◽  
pp. 92-95 ◽  
Author(s):  
Kui Chen ◽  
Tian Yun Zhang ◽  
Wei Wei

Polypropylene/organo-montmorillonite (PP/OMMT) composites were investigated by XRD. Friction and wear behaviors of this composites sliding against GCr15 stainless steel were examined on M-2000 text rig in a ring-on-block configuration. Worn surfaces of PP and its composites were analyzed by SEM. The result shows that PP macromolecule chains have intercalated into OMMT layers and form intercalated nanocomposites. With the increase of mass fraction of OMMT, both wear rate and friction coefficient of composites first decrease then rise. With the increase of load, from 150 N, 200 N to 250 N, wear rate of composites increases, while friction coefficient reduces. The wear mechanisms of composites are connected with the content of OMMT. Composites were dominated by adhesive wear, abrasive wear and adhesive wear accompanied by abrasive wear respectively with the increase of OMMT content.


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