Friction and Wear Behaviour of Nanocrystalline Cobalt

Author(s):  
M. Shafiei ◽  
A. T. Alpas

The friction and wear properties of nanocrystalline cobalt (nc Co) with a grain size of 20±5 nm and a hardness of 503±13 HV were studied using a pin-on-disc tribometer. Tests performed under unlubricated sliding conditions in ambient air showed that large tribolayer area covered the nc Co’s wear track. The oxygen concentration of the tribolayer was higher than that formed on contact surfaces of microcrystalline cobalt (mc Co) with a grain size of 16±3 μm and a hardness of 299±8 HV tested under the same conditions, due to the higher tendency of nc Co for oxidation. Higher rate of oxidational wear in nc Co resulted in higher initial surface damage in this material compared to the mc Co. Once the tribolayer was formed on top of the contact surfaces, a steady-state wear regime prevailed, reducing the coefficient of friction (COF) and the wear rate in this sample.

Author(s):  
M. Shafiei ◽  
A. T. Alpas

The tribological behaviours of conventional nickel with a grain size of 20±5 μm and nanocrystalline (nc) nickel with a grain size of 15±3 nm were compared. A pin-on-disc tribometer was employed for the friction and wear measurements under unlubricated conditions in ambient air with ∼35% relative humidity. As the grain size was decreased to the nanometer size, a reduction of about 18% was observed in the peak value of coefficient of friction (COF), but the steady-state COF remained almost unchanged. Also it was shown that the wear rate of nc nickel was about 82% lower than that of conventional nickel at 2 N load. This behaviour is mainly attributed to considerable reduction in plastic deformation and microplowing due to increased hardness.


2011 ◽  
Vol 188 ◽  
pp. 49-54 ◽  
Author(s):  
Wei Zhao ◽  
N. He ◽  
L. Li

Titanium alloys are known for their strong chemical reactivity with surrounding gas due to their high chemical affinity, especially in dry machining. But it is very difficult to study the influence of surrounding gas on the tool-workpiece interface because of the machining processes’ complexity. In this paper, rotating pin-on-disc friction tests have been carried out at room temperature in ambient air and nitrogen gas to investigate the friction and wear behavior of WC-Co cemented carbide sliding against Ti6Al4V alloy. Scanning electron microscope (SEM) and Energy dispersive x-ray spectroscopy (EDX) have been used to examine the worn surface of the WC-Co pin and Ti6Al4V disc. The result shows that, compared to air, nitrogen gas brings a slight decrease in coefficient of friction, but a significant deduction in wear of the pin and disc. The SEM observation and EDX analysis indicate a distinct difference in wear mechanism between the pin and disc. Severe grooved wear, squeezing, adhering and tearing interactions are the main mechanisms causing the extensive wear of Ti6Al4V disc. Abrasion, adhesion and “pulling out” are the main mechanisms resulting in the wear of WC-Co pin.


2017 ◽  
Vol 14 (3) ◽  
pp. 188-192
Author(s):  
Suraj R. ◽  
Jithish K.S.

Purpose This paper aims to present a comparative study of the wear properties of ferrous welded materials like EN8, EN9 and mild steel (MS). Design/methodology/approach The material is cut into specific dimension after hardfacing and is studied for the wear properties of the material. The wear testing is done on a pin-on-disc apparatus. The microhardness of the material is studied using the Vickers microhardness measuring apparatus. Findings The wear properties of ferrous welded materials like EN8, EN9 and MS are studied. It is found the MS has the least wear when compared to EN8 and EN9. The microhardness of MS is higher than EN8 and EN9, thus making it more wear-resistant than EN8 and EN9. The coefficient of friction in the dry sliding condition is found to be constant throughout the experiment. Research limitations/implications Major restriction is the amount of time required for use-wear analysis and replication experiments that are necessary to produce reliable results. These limitations mean that the analysis of total assemblages with the intention of producing specific results, especially of worked materials, is not feasible. Practical implications Generally, the complexity and rigour of the analysis depend primarily on the engineering needs and secondarily on the wear situation. It has been the author’s experience that simple and basic wear analyses, conducted in the proper manner, are often adequate in many engineering situations. Integral and fundamental to the wear analysis approach is the treatment of wear and wear behaviour as a system property. As a consequence, wear analysis is not limited to the evaluation of the effects of materials on wear behaviour. Wear analysis often enables the identification of nonmaterial solutions or nonmaterial elements in a solution to wear problems. For example, changes in or recommendations for contact geometry, roughness, tolerance and so on are often the results of a wear analysis. Originality/value The value of the work lies in the utility of the results obtained to researchers and users of the EN8, EN9 and EN24 material for their components.


2013 ◽  
Vol 423-426 ◽  
pp. 797-800 ◽  
Author(s):  
Tao Ding ◽  
Wen Jing Xuan ◽  
Yu Mei Li ◽  
Shu Fen Xiao

An experimental study on friction and wear properties of carbon strip rubbing against copper contact wire was carried out on a pin-on-disc frictional tester under electric current. The result indicates that the coefficient of friction slowly increases with increasing of electric current. The value of friction coefficient is low, generally not more than 0.125. The wear volume of pin specimen increases with increasing of electric current. The wear volume of pin specimen is very low, generally not more than 0.075g. Through observing the SEM morphology of worn specimens, it can be found that there are obvious pits of arc ablation and traces of melting metal on worn surface. Worn surfaces of the worn specimens are analyzed by an energy dispersive X-ray spectroscopy. It can be observed that the oxidation wear occurs in the frictional process due to arc erosion and significant temperature rise. Therefore the arc erosion and oxidation wear are a main wear mechanism accompanied by materials transferring in the process of electrical sliding friction.


2019 ◽  
Vol 70 (10) ◽  
pp. 3592-3596

Dry sliding friction and wear behavior of single-wall (SW) and multi-wall (MW) carbon nanotubes (CNTs)/ vinylester composite have been investigated, under several loads and sliding speeds. Three different contents (0.1, 0.15 and 0.2 wt. %) of SWCNT and MWCNTs have been dispersed into the vinylester resin in order to obtain polymer nanocomposites. The present study discusses the coefficient of friction, specific wear rate and friction stability of vinylester composites with different CNTs content, using a pin-on-disc test. The friction and wear experiments were carried out following 3 loads×3 speeds, as test parameters. The best combination of friction and wear properties was found with the nanocomposite containing 0.2 wt.% MWCNT. Keywords: carbon nanotubes, vinylester, friction, wear


2017 ◽  
Vol 69 (5) ◽  
pp. 715-722 ◽  
Author(s):  
Sanjay Mohan Sharma ◽  
Ankush Anand

Purpose This paper aims to investigate the effect of CaF2 (calcium fluoride) addition as a solid lubricant on the friction and wear behaviour of sintered Fe-Cu-C materials under different loads. Design/methodology/approach In this study, the effects of CaF2 added in varying weight percentages on the friction-wear properties of Fe-2Cu-0.8C alloys are investigated. Five Fe-2Cu-0.8C-based compositions comprising CaF2 in 0, 3, 6, 9 and 12 Wt.% were prepared using the single-stage compaction and sintering technique. Friction coefficient, wear loss, hardness and compressive strength of the specimens were measured. The worn-out surfaces were analysed using a scanning electron microscope. Friction and wear tests were carried out on pin-on-disc machine under dry sliding conditions at room temperature. Findings The alloy with 3 Wt.% CaF2 was found to be useful in improving wear and friction properties, whereas higher contents of CaF2 resulted in increased wear and friction. Apart from enhanced tribological properties, a slight decrease in the compressive strength was also observed in the 3-Wt.%-CaF2-added sample. Adhesion and abrasion were the prominent wear types observed during this study. Originality/value A new self-lubricating composite is developed where CaF2 is used as a solid lubricant in a Fe-Cu-C-based matrix. CaF2, being a high-temperature lubricant, is tried and tested for friction and wear at room temperature, and the results show that the addition of CaF2 in Fe-Cu-C improved its friction and wear properties. Thus, the developed material can be used for antifriction applications.


2012 ◽  
Vol 602-604 ◽  
pp. 2210-2213
Author(s):  
Tao Ding ◽  
Yu Mei Li ◽  
Qiu Dong He ◽  
Wen Jing Xuan

An experimental study on friction and wear properties of carbon strip rubbing against copper contact wire was carried out on a pin-on-disc frictional tester with and without windy conditions. The result shows that wear rate of pin specimen increases observably with increasing sliding distance with and without windy conditions. While the coefficient of friction slightly decreases with increasing of electric current with and without the wind. Observing the SEM morphology of pin specimens, it can be found that delamination wear is a main wear mechanism under no windy condition. While arc erosion is a dominant wear mechanism with windy condition. Worn surfaces of the materials were analyzed by an energy dispersive X-ray spectroscopy. It can be observed that oxidation wear occurs in the frictional process due to arc erosion and high temperature rise.


2019 ◽  
Vol 70 (10) ◽  
pp. 3592-3596
Author(s):  
Adrian Cotet ◽  
Marian Bastiurea ◽  
Gabriel Andrei ◽  
Alina Cantaragiu ◽  
Anton Hadar

Dry sliding friction and wear behavior of single-wall (SW) and multi-wall (MW) carbon nanotubes (CNTs)/ vinylester composite have been investigated, under several loads and sliding speeds. Three different contents (0.1, 0.15 and 0.2 wt. %) of SWCNT and MWCNTs have been dispersed into the vinylester resin in order to obtain polymer nanocomposites. The present study discusses the coefficient of friction, specific wear rate and friction stability of vinylester composites with different CNTs content, using a pin-on-disc test. The friction and wear experiments were carried out following 3 loads�3 speeds, as test parameters. The best combination of friction and wear properties was found with the nanocomposite containing 0.2 wt.% MWCNT.


2021 ◽  
Vol 1032 ◽  
pp. 163-171
Author(s):  
Jing Guan ◽  
Xue Ting Jiang ◽  
Xing Cheng ◽  
Feng Yang ◽  
Jing Liu

The surface of Ti6Al4V alloy was rapidly carburized by high-frequency electromagnetic induction heating under vacuum. The microstructure and hardness of the carburized layer were studied. The wear properties of the carburized layer were tested at 50, 100 and 200 rpm using the end face friction and wear device, and the wear mechanism was analyzed. The results show that the TiC strengthening phase was formed on the surface of Ti6Al4V alloy after high-frequency induction carburization, and the surface grains were refined. The surface hardness reaches 1116 HV0.25, but the brittleness of the carburized layer increases with increasing temperature. The amount of wear was reduced by 54% at 100 rpm. The roughness of the wear scar was reduced from 3.26 μm to 2.28 μm of Ti6A14V alloy matrix. The coefficient of friction and wear rate increases with increasing speed. The wear mechanism was transformed from adhesive wear and oxidative wear of the substrate to abrasive wear after carburizing.


Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 1127-1138 ◽  
Author(s):  
Fengjun Wei ◽  
Bingli Pan ◽  
Juan Lopez

Abstract A kind of carbon fabric/epoxy composite was successfully prepared with carbon fiber fabric as reinforced phase and epoxy resin as binder phase, then the nano-TiO2 and a hybrid system of TiO2/MWNTs was added into the carbon fabric/ epoxy composite matrix respectively to prepare a kind of nano-composite. The friction and wear properties of CF/EP composites under different load conditions have been studied in this article, during the study the effects of filler types and contents on the tribological properties were researched, at last the worn surfaces were investigated and the abrasion mechanism was discussed. The results showed that: whether filling the nano-TiO2 alone or mixing the TiO2/MWNTs, it was able to achieve a good effect on decreasing friction and reducing wear, and the optimum addition ratio of the nano-TiO2 particles was 3.0% , meanwhile 3.0% of nano-TiO2 and 0.4% of MWNTs could cooperate with each other in their dimension, and could show a synergistic effect on modifying the tribological properties of CF/EP composites, the coefficient of friction of the modified composites decreased by 20% and the wear life increased by more than 140% compared with that of pristine composite materials, in the process of friction and wear, the wear form of the composites materials varied from brittle rupture to abrasive wear gradually.


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