The Experts below are selected from a list of 5406 Experts worldwide ranked by ideXlab platform
H E G Powrie - One of the best experts on this subject based on the ideXlab platform.
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scuffing detection of tu3 cam follower contacts by electrostatic charge condition monitoring
Tribology International, 2010Co-Authors: J E Booth, T J Harvey, R J K Wood, H E G PowrieAbstract:The increasing costs associated with lubricant development and qualification has driven the need for condition monitoring techniques to be deployed on test engines to maximise information gained from expensive testing programmes. This paper discusses the results from a motorised TU3 engine with electrostatic sensors focused on the cams. System characterisation tests and an oil starvation test were used to decouple charge mechanisms associated with a Lubricated Wear test, accelerated through the use of carbon black. Cross-correlation of various charge signal processing techniques, scanning electron microscopy and profilometry revealed that tribocharging dominated during running-in/mild Wear and contact potential difference (CPD) dominated during the progression of severe adhesive Wear. Tribocharging (the charge generated by a low conductivity fluid) has been shown to be affected by oil temperature, cam rotation speed and the presence of charged species within the lubricant. Contact potential differences was principally generated by the work function difference between oxidised and nascent regions associated with adhesive Wear on the cam surface. Electrostatic monitoring which is sensitive to lubricant chemistry and Wear, and can be implemented in an industry standard engine, has great potential for the lubricant industry.
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effect of oil quality on electrostatic charge generation and transport
Journal of Electrostatics, 2002Co-Authors: T J Harvey, R J K Wood, Guy Denuault, H E G PowrieAbstract:This paper presents an experimental investigation into the effect of lubricating oil quality on tribocharging. The work forms part of a larger investigation into the causes of electrostatic charging events detected prior to severe scuffing during base oil Lubricated Wear experiments. A variable speed spinning disc charger was used for measurements of tribocharging, whilst controlling the oil viscosity, temperature, ageing and disc surface roughness. The results are discussed with reference to interactions between the double layer and fluid boundary layers and shear stress which could lead to charge separation at the disc-oil interface. Viscosity and surface roughness have been shown to affect the tribocharging of a base oil in a direct relationship, while temperature effects indicate a maxima due to transportation-recombination competition. Ageing experiments indicate an increase in conductivity, which will eventually lead to an increase in charging ability. Charge sign inversion is discussed in relation to specific adsorption of charged species (additives) on the disc surface, the presence of oppositely charged impurities and the differential of adsorption and/or diffusion rates for the negatively and positively charged species within the oils.
E.p. Georgiou - One of the best experts on this subject based on the ideXlab platform.
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Lubricated Wear behavior of leaded α β brass
Tribology International, 2012Co-Authors: C N Panagopoulos, E.p. Georgiou, K SimeonidisAbstract:Abstract In this research investigation, the Lubricated Wear behavior of leaded α+β brass sliding against stainless steel counterface was studied with the aid of a pin-on-disk apparatus. The main objective of this work was to study the effect of aqueous based environments on the interface and tribological characteristics of this tribosystem, as in several cases the formation of a thin corrosion product layer can act as a lubricating film, decreasing the coefficient of friction of the tribosystem. Thus distilled water and 3.5% NaCl solutions were used as possible lubricants and were then compared with a commercial SAE 80 W lubricant, which is extensively used in many light and heavy-duty, automotive, commercial or industrial applications. From the experimental results obtained, Stribeck curves for each lubricative environment were exacted and analyzed. In addition, by evaluating changes in the coefficient of friction of the tribosystem in accordance with the observed Wear mechanisms, the characteristic lubrication regimes (elastodynamic, mixed and boundary) were identified in these curves.
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Cold rolling and Lubricated Wear of 5083 aluminium alloy
Materials & Design, 2010Co-Authors: Chr. Panagopoulos, E.p. GeorgiouAbstract:Abstract The effect of cold deformation on the Lubricated Wear of 5083 aluminium alloy was investigated. SAE 10W was selected as liquid lubricant. The aluminium alloy was submitted to a cold rolling process, until the average thickness of the specimens was reduced by 7% and 15% respectively. From the experimental results obtained, the Stribeck curves for the as received and cold rolled aluminium alloy specimens were exacted. In all cases the three lubrication regimes were identified. In addition, the cold deformation process has led to a decrease of the friction coefficient of the tribosystem: 5083 aluminium alloy–410 stainless steel, for the same Wear conditions (applied load, sliding speed and lubricant). The dominant Wear mechanisms in each lubrication regime were studied via Scanning Electron Microscopy (SEM).
Liping Wang - One of the best experts on this subject based on the ideXlab platform.
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tribological behavior of plasma electrolytic oxidation coating on magnesium alloy with oil lubrication at elevated temperatures
Journal of Alloys and Compounds, 2009Co-Authors: Liping Wang, J K LiangAbstract:Abstract The ceramic coating with micro-pores structure on AM60B magnesium alloy was prepared in silicate electrolyte by plasma electrolytic oxidation (PEO) method. The PEO coating is mainly composed of percales MgO and forsterite Mg 2 SiO 4 phases. The tribological performance of the PEO coatings and uncoated magnesium alloys under oil-Lubricated Wear conditions at different loads and elevated temperatures (80–120 °C) was comparatively investigated. Results shown that the PEO coating exhibited significantly higher Wear resistance and relatively lower friction coefficient when compared with Mg alloy under oil-Lubricated conditions. The excellent tribological performance can be attributed to the high hardness and micro-pores structure feature of the PEO coating. Such high-performance PEO coating on magnesium alloys under oil-Lubricated conditions could be applied as attractive advanced material for a wide range of automobile engine applications.
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influence of pulse frequency on the microstructure and Wear resistance of electrodeposited ni al2o3 composite coatings
Surface & Coatings Technology, 2006Co-Authors: Li Chen, Liping Wang, Zhixiang ZengAbstract:Abstract Nickel matrix composite coatings reinforced with sub-microsized Al 2 O 3 particles were produced by pulse electrodeposition and the effect of pulse frequency on the microstructure, hardness and Wear resistance of Ni–Al 2 O 3 composite coatings were investigated. The results showed that the pulse frequency significantly influenced the preferred orientation of Ni–Al 2 O 3 composite coatings; the texture of the coatings progressively changed from a strong (111) preferred orientation to a random orientation when pulse frequency increased. The hardness of composite coatings decreased slightly with the increase of volumetric content of alumina particles. The Wear behaviors of composite coatings under dry sliding Wear and oil-Lubricated Wear conditions were different significantly. The Wear resistance of Ni–Al 2 O 3 coatings decreased with the increase of incorporated alumina particles under dry sliding Wear condition, which was largely influenced by the microstructure of Ni matrix due to the presence of adhesive Wear. However, the Wear resistance of composite coatings increased with the increase of volumetric content of the reinforcements under oil-Lubricated Wear condition, which mainly depends on the volumetric content of incorporated alumina particles because the adhesive Wear can be avoided under oil-Lubricated Wear condition.
Zhixiang Zeng - One of the best experts on this subject based on the ideXlab platform.
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influence of pulse frequency on the microstructure and Wear resistance of electrodeposited ni al2o3 composite coatings
Surface & Coatings Technology, 2006Co-Authors: Li Chen, Liping Wang, Zhixiang ZengAbstract:Abstract Nickel matrix composite coatings reinforced with sub-microsized Al 2 O 3 particles were produced by pulse electrodeposition and the effect of pulse frequency on the microstructure, hardness and Wear resistance of Ni–Al 2 O 3 composite coatings were investigated. The results showed that the pulse frequency significantly influenced the preferred orientation of Ni–Al 2 O 3 composite coatings; the texture of the coatings progressively changed from a strong (111) preferred orientation to a random orientation when pulse frequency increased. The hardness of composite coatings decreased slightly with the increase of volumetric content of alumina particles. The Wear behaviors of composite coatings under dry sliding Wear and oil-Lubricated Wear conditions were different significantly. The Wear resistance of Ni–Al 2 O 3 coatings decreased with the increase of incorporated alumina particles under dry sliding Wear condition, which was largely influenced by the microstructure of Ni matrix due to the presence of adhesive Wear. However, the Wear resistance of composite coatings increased with the increase of volumetric content of the reinforcements under oil-Lubricated Wear condition, which mainly depends on the volumetric content of incorporated alumina particles because the adhesive Wear can be avoided under oil-Lubricated Wear condition.
K Simeonidis - One of the best experts on this subject based on the ideXlab platform.
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Lubricated Wear behavior of leaded α β brass
Tribology International, 2012Co-Authors: C N Panagopoulos, E.p. Georgiou, K SimeonidisAbstract:Abstract In this research investigation, the Lubricated Wear behavior of leaded α+β brass sliding against stainless steel counterface was studied with the aid of a pin-on-disk apparatus. The main objective of this work was to study the effect of aqueous based environments on the interface and tribological characteristics of this tribosystem, as in several cases the formation of a thin corrosion product layer can act as a lubricating film, decreasing the coefficient of friction of the tribosystem. Thus distilled water and 3.5% NaCl solutions were used as possible lubricants and were then compared with a commercial SAE 80 W lubricant, which is extensively used in many light and heavy-duty, automotive, commercial or industrial applications. From the experimental results obtained, Stribeck curves for each lubricative environment were exacted and analyzed. In addition, by evaluating changes in the coefficient of friction of the tribosystem in accordance with the observed Wear mechanisms, the characteristic lubrication regimes (elastodynamic, mixed and boundary) were identified in these curves.
