Humidity-dependent friction mechanism in an ultrananocrystalline diamond film

Kumar, N.; Radhika, R.; Kozakov, A. T.; Sankaran, Kamatchi Jothiramalingam; Dash, S.; Tyagi, A.K.; Tai, Nyan‐Hwa; Lin, I‐Nan

doi:10.1088/0022-3727/46/27/275501

Cited by 57 publications

(54 citation statements)

References 28 publications

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“…[10,11] PCC5 showed a larger absorption volume than PCC0 and PCC3 (Figure 2 b), which indicates a higher surface area and larger pore volume with a favorable pore size distribution. [46][47][48] Similarly, in the core-level O 1s spectra, the appearance of peaks at binding energies of 534.7, 533.2, 530.8, and 529.9 eV also reflects the presence of the functional groups noted above. Both PCC3 and PCC5 have a pore size around 3-4 nm, whereas the pore size of PCC0 is less than 2 nm.…”

Section: Resultsmentioning

confidence: 84%

“…Notably, the BET surface area obtained for PCC5 is comparable to the highest value ever reported for AC obtained from a biomass precursor. [46,47] An increased intensity of all the peaks is noted with increased KOH concentration, which suggests clearly that the activating agent plays a vital role to develop these active functional groups. The pore size distributions of all the samples measured by N 2 adsorption are illustrated in Figure 2 C. These indicate that the addition of KOH significantly affects the pore size distribution, and an increased KOH weight ratio can enlarge the pore size (Figure 2 c).…”

Section: Resultsmentioning

confidence: 93%

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Construction of High‐Energy‐Density Supercapacitors from Pine‐Cone‐Derived High‐Surface‐Area Carbons

et al. 2014

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Very high surface area activated carbons (AC) are synthesized from pine cone petals by a chemical activation process and subsequently evaluated as an electrode material for supercapacitor applications in a nonaqueous medium. The maximum specific surface area of ∼3950 m(2) g(-1) is noted for the material treated with a 1:5 ratio of KOH to pine cone petals (PCC5), which is much higher than that reported for carbonaceous materials derived from various other biomass precursors. A symmetric supercapacitor is fabricated with PCC5 electrodes, and the results showed enhanced supercapacitive behavior with the highest energy density of ∼61 Wh kg(-1). Furthermore, outstanding cycling ability is evidenced for such a configuration, and ∼90 % of the initial specific capacitance after 20,000 cycles under harsh conditions was observed. This result revealed that the pine-cone-derived high-surface-area AC can be used effectively as a promising electrode material to construct high-energy-density supercapacitors.

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Section: Resultsmentioning

confidence: 84%

Section: Resultsmentioning

confidence: 93%

Construction of High‐Energy‐Density Supercapacitors from Pine‐Cone‐Derived High‐Surface‐Area Carbons

et al. 2014

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“…3a, c. Under 5% and 7% RH conditions, there are similar variation in friction coefficient and run-in periods. It is likely due to sticking of the slider during the first few small-amplitude cycles, and this phenomenon may be called 12 "stick slip". Test performed at 5% RH, it always exhibites an induction period, so-called "run in" period, during which the friction coefficients reach the highest value (the initial maximum friction coefficient ~0.47 for 10 N and ~0.4 for 20 N) and gradually decrease before reaching an low steady-state friction coefficient (~0.04 for 10 N and ~0.06 for 20 N) (Fig.…”

Section: Run-in Period Performance Dependent On the Rh Levelsmentioning

confidence: 99%

Understanding integrated effects of humidity and interfacial transfer film formation on tribological behaviors of sintered polycrystalline diamond

2015

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Polycrystalline diamond (PCD) used in down-hole tool applications is ideally suit for harsh environments such as drilling at circulation break and poor lubrication, in which the water molecules of physical and chemical adsorption can severely affect the tribochemistry effect across cutting interface. Here, tribological behaviors of PCD are studied in a controlled humid atmosphere (5%-50% RH). The friction coefficient is ~ 0.04 under 5% RH condition, which is significantly increased to ~ 0.11 under 50% condition.The run-in period and wear rate of PCD decrease while increasing RH levels during the tribotest. Such an ultra-low friction coefficient regime is explained coincide with the formation of efficient carbonaceous transfer films in the run-in periods through ex situ, micro-laser Raman spectroscopy and Atomic Force Microscope (AFM) measurements.Abstract graph: This paper highlights an intimate relationship among RH levels, dangling bonds passivation, run-in periods, transfer films formation and tribological behaviors.3 bits due to its extremely high wear resistance, high hardness and excellent toughness.Among these applications, fluids such as water, drilling mud and gas, are always required to lubricate the surfaces and interfaces of PCD in down-hole applications and its counter frictional pair. 1-4 Previous works have focused on that diamond rubbing against diamond in the presence of oil and water based drilling fluids had a coefficient of friction between 0.05 and 0.08. 5 Sexton et al. 6 investigated the bearing wear rates in laboratory testing and results showed that PCD thrust bearings provide a long-lasting bearing solution for down-hole drilling tools. Knuteson et al. 7 reported that the friction coefficient values of PCD thrusting bearing decreased in the lubrication regime moving from boundary to mixed-mode and may even become hydrodynamic. Mehan et al. 8 measured the wear rates of PCD and pointed out that wear mechanism of PCD was the result of diamond particles falling off in pin-on-disk tribometer experiments. However, the above works only concentrated on the mechanical aspects of wear performance and have not addressed the role of service environment factors on the friction coefficient, wear and ultimate failure wear of PCD. Considering the operating conditions such as high speeds, high loads, run-in period, frequent starting and stopping, cyclic fluctuating loads and extreme conditions such as drilling at circulation break and poor lubrication, the PCD contact surfaces cannot be ensured keeping in liquid lubrication condition all the time. We have confirmed from tribological behaviors of PCD under different relative humidity (RH) that friction coefficient, wear and adhesion behaviors are significantly affected by the adsorbed water molecules which can have distinct impacts on physical and chemical properties of solid surfaces. Understanding the effects of the relative humidity on sliding interface would be 5 formation of a transfer layer, possibly graphitic in nature. 19 Transfer films are known t...

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“…Various forms of carbon materials are used to regulate the process of friction and wear [1][2][3][4][5][6]. Among them, diamond-like carbon (DLC) films have been extensively studied for two decades due to their low deposition temperature, high hardness, superior surface finish, and unusual combination of high wear-resistance and low friction under a broad range of conditions [1,[7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Among them, diamond-like carbon (DLC) films have been extensively studied for two decades due to their low deposition temperature, high hardness, superior surface finish, and unusual combination of high wear-resistance and low friction under a broad range of conditions [1,[7][8][9]. However, like other carbon materials [2][3][4][5], the friction behaviors of DLC films are susceptible to the test environments, especially the humidity therein [10][11][12]. Hydrogenated DLC films can give superlow friction coefficients in dry environments but relatively high friction coefficients when the humidity is high enough [10,11].…”

Section: Introductionmentioning

confidence: 99%

Environmental effect on the load-dependent friction behavior of a diamond-like carbon film

Cui

Wang

2015

Tribology International

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Humidity-dependent friction mechanism in an ultrananocrystalline diamond film

Cited by 57 publications

References 28 publications

Construction of High‐Energy‐Density Supercapacitors from Pine‐Cone‐Derived High‐Surface‐Area Carbons

Construction of High‐Energy‐Density Supercapacitors from Pine‐Cone‐Derived High‐Surface‐Area Carbons

Understanding integrated effects of humidity and interfacial transfer film formation on tribological behaviors of sintered polycrystalline diamond

Environmental effect on the load-dependent friction behavior of a diamond-like carbon film

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