Tribological Properties of Rock Bit Journal Bearings for Journal with Nanosecond Laser Surface Texture

The effect of nanoscale surface texture on the frictional and wear performances of nanocrystalline diamond films under water-lubricating conditions were comparatively investigated using a reciprocating ball-on-flat tribometer. Although the untreated nanocrystalline diamond film shows a stable frictional state with an average friction coefficient of 0.26, the subsequent textured films show a beneficial effect on rapidly reducing the friction coefficient, which decreased to a stable value of 0.1. Furthermore, compared with the nanocrystalline diamond coating, the textured films showed a large decreasing rate of the corresponding ball wear rate from 4.16 × 10−3 to 1.15 × 10−3 mm3/N/m. This is due to the fact that the hydrodynamic fluid film composed of water and debris can provide a good lubrication environment, so the entire friction process has reached the state of fluid lubrication. Meanwhile, the surface texture can greatly improve the hydrophilicity of the diamond films, and as the texture density increases, the water contact angle decreases from 94.75° of the nanocrystalline diamond film to 78.5° of the textured films. The proper textured diamond film (NCD90) exhibits superior tribological properties among all tested diamond films, such as short run-in period, low coefficient of friction, and wear rate.

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Microstructure and surface texture driven improvement in in-vitro response of laser surface processed AZ31B magnesium alloy

Journal of Magnesium and Alloys ◽

10.1016/j.jma.2020.11.002 ◽

2021 ◽

Author(s):

Tso-Chang Wu ◽

Sameehan S. Joshi ◽

Yee-Hsien Ho ◽

Mangesh V. Pantawane ◽

Subhasis Sinha ◽

...

Keyword(s):

Magnesium Alloy ◽

Surface Texture ◽

Laser Surface ◽

Az31b Magnesium Alloy ◽

In Vitro Response

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Effect of Micro-Manufacturing Processes on Surface Behavior

ASME 2007 International Manufacturing Science and Engineering Conference ◽

10.1115/msec2007-31113 ◽

2007 ◽

Cited By ~ 1

Author(s):

Tiffany Davis ◽

Jian Cao ◽

Wei Chen ◽

Q. Jane Wang ◽

Cedric Xia ◽

...

Keyword(s):

Surface Texture ◽

Surface Texturing ◽

Steel Sample ◽

Laser Surface ◽

Laser Surface Texturing ◽

Copper Sheet ◽

Property Variation ◽

Nano Indentation ◽

Interface Surface ◽

Significant Difference

Surface texturing has become a valuable technique for reducing friction and wear in contacting parts; laser surface texturing is one such method used to create micro-dimples on the interface surface. This work investigates the surface material property variation caused by laser surface texturing. The hardness and modulus of elasticity of a steel laser surface texture sample were evaluated near the dimples and away from the dimpled zone through nano-indentation. Resulting data shows that no significant difference exists between the material properties from the two positions. An alternate technique for surface texture generation was also explored, involving the use of micro-punches to create surface features in a metal sample. Computational simulations were performed using a second material underneath a thin copper sheet. The second material was present to serve as a support and to allow extensive deformation of the top material. The choice of the support material and ratio of material thicknesses was optimized to minimize pile up. Trials were conducted for three base supporting materials: PTFE, PMMA, and aluminum. Results show that PMMA performed better than the other materials. Positive deflection was minimized when the PMMA thickness was at least fifteen times that of the copper sheet. Physical experiments were completed with a thin copper sheet to verify the results. An array of micro-indentations was also created in a bulk steel sample. In order to assess the effect of dimpling via micro-forming, nano-indentation was performed near and far from the deformed material of the dimples. Similar to the laser textured sample, no significant differences were found between the two locations.

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Numerical and experimental study on the effect of surface texture with roughness orientation considered under a mixed lubrication state

Industrial Lubrication and Tribology ◽

10.1108/ilt-06-2021-0204 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Junru Wang ◽

Quandai Wang ◽

Yueyan Li ◽

Meiling Guo ◽

Pengyang Li ◽

...

Keyword(s):

Surface Texture ◽

Surface Texturing ◽

Mixed Lubrication ◽

Laser Surface ◽

Geometric Parameters ◽

Laser Surface Texturing ◽

Textured Surface ◽

Asperity Contact ◽

Content Type ◽

Texture Parameters

Purpose The purpose of this paper is to investigate the effects of surface texture with roughness orientation considered on tribological properties under a mixed lubrication state numerically and experimentally. Design/methodology/approach Based on the average Reynolds equation and asperity contact model, the impacts of surface texture parameters and roughness orientation on lubrication properties have been calculated using finite difference method. Tin–bronze samples with various prescribed surface texture geometric parameters and roughness orientation were fabricated by laser surface texturing technique, and the tribology performance of the textured surface was studied experimentally. Findings The effects of surface geometric parameters and roughness orientation parameters have been discerned. The experimental observations are in good agreement with the numerical prediction, which suggests that the numerical scheme adopted in this work is suitable in capturing the surface texture and roughness effect under mixed lubrication state. Originality/value By meticulously controlling the surface roughness and surface texture geometric characteristics based on the laser surface texturing process, samples with prescribed surface texture parameters and roughness orientation consistent with that in theoretical studies were fabricated and the theoretical model and results were verified experimentally.

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