Effection of calcium phosphate tribofilm on anti-shudder performance in ATFs

Li, Shaohui; Di, Zechao; Zhao, Zhiyu; Liu, Yang; Xu, Jingjing; Cui, Haitao; Huang, Danqiong; Liu, Zhongguo; Li, Yang

doi:10.1016/j.triboint.2017.12.017

Cited by 6 publications

(5 citation statements)

References 17 publications

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“…4(b)). This phenomenon is consistent with our previous research; that is, the CaP tribofilm contributes to maintaining the antishudder property [19]. The slope of μ-v curves for ATF-C slowly decreases, and there is little difference in slope value every 24 h. Until the antishudder characteristic disappears at 120 h, a very sparse tribofilm remains on the steel surface (as shown in Fig.…”

Section: Friction Resultssupporting

confidence: 92%

“…The friction coefficient at various speeds, loads, and temperatures were recorded. The test procedure was carried out according to JASO M349 for LVFA [19,20,25]. The tribological testing for each condition was done in triplicate.…”

Section: Tribological Testingmentioning

confidence: 99%

“…Antishudder performance of wet clutches can be modulated by FMs and other additives in ATFs [16−18]. Our previous study found that a CaP tribofilm formed by FM and detergent affected friction characteristics [19,20]. Zhao et al [8,21] investigated the chemical composition of tribofilms containing P and Ca on the steel friction plate of the clutch.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of calcium phosphate (CaP) tribofilms from commercial automatic transmission fluids (ATFs) and their correlation with antishudder performance

Di¹,

Xu²,

Liu³

et al. 2019

Friction

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The friction properties of wet clutches are highly dependent on the surface tribofilms formed by automatic transmission fluids (ATFs). Here, four commercial ATFs were evaluated with a disc-on-disc tribometer to study tribofilm formation on steel surfaces and the effects of tribofilms on the friction properties. The chemical composition, stoichiometry, structure, and thickness of the tribofilms were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS). Calcium phosphate (CaP) tribofilms form on the friction surface with all ATFs, which contributes to their antishudder characteristics. The thickness and surface coverage of CaP tribofilms are positively correlated with their antishudder properties.

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Section: Friction Resultssupporting

confidence: 92%

Section: Tribological Testingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of calcium phosphate (CaP) tribofilms from commercial automatic transmission fluids (ATFs) and their correlation with antishudder performance

Di¹,

Xu²,

Liu³

et al. 2019

Friction

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“…5,6 To stabilize the phosphate, facilitate AW tribofilm growth, and adjust frictional properties, it is common to add calcium additives that act as counterions. 7 It is suspected that the calcium also modifies mechanical properties of the film in terms of hardness or modulus. However, the exact process of formation is not known as much of the work has focused on analyzing end-of-test surfaces long after the film has formed.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Carefully designed additives in transmission fluids can form nanometer-scale physicochemical surface films, called antiwear (AW) tribofilms, which provide wear protection and low friction between the surfaces in a sliding contact and function to minimize energy loss and increase vehicle efficiency to meet stringent CO 2 emission standards. − Analyzing the mechanism of how AW tribofilms form and how surface chemistry can be used to control their functionality is necessary for developing more efficient lubricants. In particular, phosphorus AW tribofilms are formed on loaded rolling and/or sliding surfaces in contact from phosphorus-containing lubricants and serve to protect the surfaces from wear and fatigue processes in various machine elements, such as gears, bearings, and sliding contacts. , To stabilize the phosphate, facilitate AW tribofilm growth, and adjust frictional properties, it is common to add calcium additives that act as counterions . It is suspected that the calcium also modifies mechanical properties of the film in terms of hardness or modulus.…”

Section: Introductionmentioning

confidence: 99%

Direct Multimodal Nanoscale Visualization of Early Phosphorus-Based Antiwear Tribofilm Formation

Lorenz

Pawlicki

Hysmith

et al. 2022

ACS Appl. Mater. Interfaces

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Understanding the mechanism of antiwear (AW) tribofilm formation and how to tune surface chemistry to control functionality is essential for the development of the next generation of oil lubricants. In particular, understanding and optimizing early AW tribofilm formation can increase the energy efficiency of mechanical systems. However, the mechanism for how these films form is not well understood. The majority of prior work has focused on analyzing only end-of-test surfaces long after the film has formed. In this work, we develop an in situ multimodal chemical imaging methodology to directly visualize the early formation of AW films on steel surfaces. We investigate an oil formulation containing a phosphorus-based additive commonly used to protect surfaces from wear and fatigue processes in machine elements, such as gears, bearings, and sliding contacts. Using nanoscale multimodal chemical imaging on combined platforms of atomic force microscopy (AFM) coupled directly with in situ nano-infrared (nano-IR) spectroscopy, and further combined ex situ with time-of-flight secondary ion mass spectrometry (ToF-SIMS), we demonstrate a direct correlation between changes in friction and local surface chemistry. In these experiments, the AFM probe acts as a single asperity contact to generate the tribofilm as well as a tool to analyze it in situ as it is forming. To verify our in situ measurements, we compare these results to the ex situ ToF-SIMS of macroscale block-on-ring tribometer-formed samples. The understanding gained here on how AW films form and how film properties can be modified by tuning the chemistry of the additives will facilitate developing transmission fluids to meet increasing demands for vehicle performance and efficiency.

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Anti-vibration and traction control of rotary sliding systems by orthogonal rotation providing transverse sliding

Tadokoro

Aso

Nagamine

et al. 2021

Tribology International

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Effection of calcium phosphate tribofilm on anti-shudder performance in ATFs

Cited by 6 publications

References 17 publications

Investigation of calcium phosphate (CaP) tribofilms from commercial automatic transmission fluids (ATFs) and their correlation with antishudder performance

Investigation of calcium phosphate (CaP) tribofilms from commercial automatic transmission fluids (ATFs) and their correlation with antishudder performance

Direct Multimodal Nanoscale Visualization of Early Phosphorus-Based Antiwear Tribofilm Formation

Anti-vibration and traction control of rotary sliding systems by orthogonal rotation providing transverse sliding

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