A Novel Process for Manufacturing High-Friction Rings with a Closely Defined Coefficient of Static Friction (Relative Standard Deviation 3.5%) for Application in Ship Engine Components

In recent years, there has been an increased uptake for surface functionalization through the means of laser surface processing. The constant evolution of low-cost, easily automatable, and highly repeatable nanosecond fibre lasers has significantly aided this. In this paper, we present a laser surface-texturing technique to manufacture a surface with a tailored high static friction coefficient for application within driveshafts of large marine engines. The requirement in this application is not only a high friction coefficient, but a friction coefficient kept within a narrow range. This is obtained by using nanosecond-pulsed fibre lasers to generate a hexagonal pattern of craters on the surface. To provide a suitable friction coefficient, after laser processing the surface was hardened using a chromium-based hardening process, so that the textured surface would embed into its counterpart when the normal force was applied in the engine application. Using the combination of the laser texturing and surface hardening, it is possible to tailor the surface properties to achieve a static friction coefficient of ≥0.7 with ~3–4% relative standard deviation. The laser-textured and hardened parts were installed in driveshafts for ship testing. After successfully performing in 1500 h of operation, it is planned to adopt the solution into production.

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Standard Deviation Quantitative Characterization and Process Optimization of the Pyramidal Texture of Monocrystalline Silicon Cells

Materials ◽

10.3390/ma13030564 ◽

2020 ◽

Vol 13 (3) ◽

pp. 564

Author(s):

Zheng Fang ◽

Zhilong Xu ◽

Tao Jang ◽

Fei Zhou ◽

Shixiang Huang

Keyword(s):

Standard Deviation ◽

Relative Standard Deviation ◽

Monocrystalline Silicon ◽

Photoelectric Conversion Efficiency ◽

Textured Surface ◽

Photoelectric Conversion ◽

Photoelectric Characteristics ◽

Relative Standard ◽

Wafer Surfaces ◽

Silicon Cell

To quantitatively characterize the pyramidal texture of monocrystalline silicon cells and to optimize the parameters of the texturing process, the relative standard deviation Sh was proposed to quantitatively characterize the uniformity of the pyramidal texture. Referring to the definition and calculation of the standard deviation in mathematical statistics, Sh was defined as the standard deviation of the pyramid relative height hi after normalization of the pyramid height Hi of monocrystalline silicon wafer surfaces. Six different silicon cells, with different pyramidal textures, were obtained by applying different texturing times. The relationships between Sh and the photoelectric characteristics were analyzed. The feasibility of quantitatively characterizing the uniformity of the pyramidal texture using Sh was verified. By fitting the Sh curve, the feasibility of optimizing the texturing process parameters and predicting the photoelectric characteristics using Sh was verified. The experimental and analytical results indicate that, when the relative standard deviation Sh was smaller, the uniformity of the pyramidal texture obtained by texturing was better. The photoelectric conversion efficiency (PCE) of the silicon cells monotonically increased with decreasing Sh. The silicon cell obtained by texturing with 2% tetramethylammonium hydroxide (TMAH) solution for 18.1 min had a textured surface with a minimum of Sh, the reflectivity of the silicon cell reached its minimum value of 2.28%, and the PCE reached its maximum value of 19.76%.

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Corrosion Wear Performance of Pure Titanium Laser Texturing Surface by Nitrogen Ion Implantation

Metals ◽

10.3390/met10080990 ◽

2020 ◽

Vol 10 (8) ◽

pp. 990 ◽

Cited By ~ 1

Author(s):

Lin Cao ◽

Yun Chen ◽

Jie Cui ◽

Wei Li ◽

Zhidan Lin ◽

...

Keyword(s):

Wear Resistance ◽

Friction Coefficient ◽

Ion Implantation ◽

Surface Texturing ◽

Laser Surface ◽

Laser Surface Texturing ◽

Textured Surface ◽

Artificial Joints ◽

Nitrogen Ion Implantation ◽

Nitrogen Ion

The poor tribological performances of titanium have significantly limited its applications in the field of artificial joints. In order to solve problems regarding the wear and corrosion of artificial joints in the body, we fabricated the composite materials utilizing the combination of laser surface texturing and nitrogen ion implantation technology, and investigated the effect of laser surface texturing, nitrogen ion implantation, and different dimple area densities on tribological performance. The results show that the textured surface could reduce the friction coefficient and improve the wear resistance, and the optimum dimple density was found to be 25%. After N ion implantation, the wear resistance of the textured sample was further improved, due to the formation of the nitride layer. Moreover, as shown by the electrochemical test results, the corrosion resistance was enhanced significantly. The friction coefficient decreased the most, and the wear resistance increased by 405% with the lowest wear rate of 0.37 × 10−3 mm3/N·m. However, the specimen with a dimple density of 60% had the worst wear resistance. The results of the study provide a basis for the development and application of artificial joint materials.

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The effect of laser surface texturing to inhibit stick-slip phenomenon in sliding contact

Advances in Mechanical Engineering ◽

10.1177/1687814019874635 ◽

2019 ◽

Vol 11 (9) ◽

pp. 168781401987463

Author(s):

Hao Wang ◽

Xuan Xie ◽

Xijun Hua ◽

Bifeng Yin ◽

Hang Du ◽

...

Keyword(s):

Standard Deviation ◽

Friction Coefficient ◽

Machine Tools ◽

Laser Surface Texturing ◽

Lubricating Oil ◽

Textured Surface ◽

Slip Effect ◽

Stick Slip ◽

Adequate Amount ◽

Slip Phenomenon

Stick-slip phenomenon in some mechanical structures, especially in machine tools, should be eliminated or inhibited, otherwise the vibration will occur and the position error will inevitably be obtained. In this study, different kinds of surface textures were carried out on the lower samples of the pin-on-disk contact. The starting process of the machine tools was simulated on an Rtec-Multi-Function Tribometer. The stick-slip phenomenon was observed in each kind of samples. However, the stick-slip phenomenon of smooth sample is larger than that of the textured samples. The bulge-textured surface shows excellent anti-stick-slip effect, and the critical stick-slip speed of bulge-textured surface is 95.9% lower than that of the smooth surface. Simultaneously, the anti-stick-slip effect of bulge-textured surface is superior to that of the dent-shaped texturing surface. What’s more, when the amount of lubricating oil is 15 mL, the standard deviation values of friction coefficient and critical speed of stick-slip phenomena (rotational speed when the standard deviation of friction coefficient is abrupt) are the lowest at different rotational speeds. It can be predicted that the bulge textures and adequate amount of lubricating oil (15 mL) can eliminate stick-slip phenomenon when processed in the surface of the machine tool because the bulge textures and adequate amount of lubricating oil can improve frictional state effectively and avoid the slip of the contact surface.

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The effect of dimple size on the tribological performances of a laser surface textured palm kernel activated carbon-epoxy composite

Industrial Lubrication and Tribology ◽

10.1108/ilt-05-2016-0121 ◽

2017 ◽

Vol 69 (5) ◽

pp. 768-774 ◽

Cited By ~ 3

Author(s):

Martini Mohmad ◽

Mohd Fadzli Bin Abdollah ◽

Noreffendy Tamaldin ◽

Hilmi Amiruddin

Keyword(s):

Activated Carbon ◽

Friction Coefficient ◽

Palm Kernel ◽

Laser Surface ◽

Laser Surface Texturing ◽

Textured Surface ◽

Contact Ratio ◽

Compression Moulding ◽

Dimple Size ◽

Content Type

Purpose The purpose of this study is to investigate the effect of dimple size on the tribological performances of laser surface-textured palm kernel-activated carbon-epoxy (PKAC-E) composite. Design/methodology/approach A PKAC-E disc 74 mm in diameter was fabricated using the hot compression moulding technique. Five different types of surface contacts were prepared using a CO2 laser surface-texturing machine: a non-textured surface, and surfaces with dimples between 500 and 1,200 μm in diameter. The area density, contact ratio and depth were kept constant. A sliding test was carried out using a ball-on-disc tribometer under boundary lubricated conditions with constant sliding speed, sliding distance and applied load. Findings In general, the results showed that the friction coefficient decreased with an increasing dimple diameter of surface-textured PKAC-E composite. However, the appropriate dimple diameter for maintaining low friction coefficient is proposed in the range of 800 to 1,000 μm. Originality/value This is the first study, to the authors’ knowledge, to investigate the effects of dimple size, which is larger than 500 μm, on the tribological performances of laser surface-textured PKAC-E composite.

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Fretting friction properties of laser surface texture microfilaments

Industrial Lubrication and Tribology ◽

10.1108/ilt-07-2019-0242 ◽

2019 ◽

Vol 72 (3) ◽

pp. 427-431

Author(s):

Ke Li ◽

Xiuping Dong ◽

Mingji Huang ◽

Ping Chen

Keyword(s):

Wear Resistance ◽

Friction Coefficient ◽

Surface Texture ◽

Laser Surface ◽

Laser Surface Texturing ◽

Textured Surface ◽

Wear Depth ◽

Content Type ◽

Texture Density ◽

Metal Rubber

Purpose This paper aims to improve the wear resistance of metal rubber microfilaments and the service life. The effect of surface texture by laser processing on the fretting friction properties of metal rubber microfilaments was studied. Design/methodology/approach The LQL-F20A laser marking machine was used to fabricate a ring groove array with equal spacing and dense arrangement on the surface of metal rubber microfilaments. The test was carried out with a self-made micro-dynamic frictional tester. The topography of the microfilaments was observed by scanning electron microscopy and analyzed. Findings It has shown that laser surface texturing can improve the wear performance of microfilaments. Under the same experimental conditions, the microfilaments of textured surface has a smaller depth of wear than un-textured specimen. The wear resistance increases with the increase of texture density. The friction coefficient of textured specimen is significantly reduced compared with un-textured specimen, and the surface texture density of microfilaments has little influence on the friction coefficient after stabilization. In the stage of stable fretting wear, the wear depth will be more with the increase of the load. Originality/value There is little research on metal rubber microfilaments tribological properties. In this paper, the effect of laser texturing of microfilaments on micro-dynamic friction properties was studied by friction machine to provide a reference for the application of metal rubber in aerospace, medical and other fields.

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An Automated Procedure for the Determination of Ammonia in Tobacco

Beiträge zur Tabakforschung International/Contributions to Tobacco Research ◽

10.2478/cttr-2013-0287 ◽

1972 ◽

Vol 6 (4) ◽

Cited By ~ 1

Author(s):

P.F. Collins ◽

W.W. Lawrence ◽

J.F. Williams

Keyword(s):

Standard Deviation ◽

Relative Standard Deviation ◽

Distillation Method ◽

Relative Standard ◽

Tobacco Sample ◽

Automated Determination

AbstractA procedure for the automated determination of ammonia in tobacco has been developed. Ammonia is extracted from the ground tobacco sample with water and is determined with a Technicon Auto Analyser system which employs separation of the ammonia through volatilization followed by colourimetry using the phenate-hypochlorite reaction. The procedure has been applied to a variety of tobaccos containing from 0.02 to 0.5 % ammonia with an overall relative standard deviation of 2 %. The accuracy of the procedure as judged by recovery tests and by comparison to a manual distillation method is considered adequate

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How Certain Are the Reported Ionic Conductivities of Thiophosphate-Based Solid Electrolytes? an Interlaboratory Study

10.26434/chemrxiv.11316497.v2 ◽

2020 ◽

Author(s):

Saneyuki Ohno ◽

Tim Bernges ◽

Johannes Buchheim ◽

Marc Duchardt ◽

Anna-Katharina Hatz ◽

...

Keyword(s):

Standard Deviation ◽

Ionic Conductivity ◽

Relative Standard Deviation ◽

Solid Electrolytes ◽

Ionic Conductivities ◽

Ionic Conductors ◽

Energy Storage Devices ◽

Activation Barriers ◽

Storage Devices ◽

Relative Standard

Owing to highly conductive solid ionic conductors, all-solid-state batteries attract significant attention as promising next-generation energy storage devices. A lot of research is invested in the search and optimization of solid electrolytes with higher ionic conductivity. However, a systematic study of an interlaboratory reproducibility of measured ionic conductivities and activation energies is missing, making the comparison of absolute values in literature challenging. In this study, we perform an uncertainty evaluation via a Round Robin approach using different Li-argyrodites exhibiting orders of magnitude different ionic conductivities as reference materials. Identical samples are distributed to different research laboratories and the conductivities and activation barriers are measured by impedance spectroscopy. The results show large ranges of up to 4.5 mScm-1 in the measured total ionic conductivity (1.3 – 5.8 mScm-1 for the highest conducting sample, relative standard deviation 35 – 50% across all samples) and up to 128 meV for the activation barriers (198 – 326 meV, relative standard deviation 5 – 15%, across all samples), presenting the necessity of a more rigorous methodology including further collaborations within the community and multiplicate measurements.

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Does laser surface texturing really have a negative impact on the fatigue lifetime of mechanical components?

Friction ◽

10.1007/s40544-021-0508-2 ◽

2021 ◽

Author(s):

Chia-Jui Hsu ◽

Andreas Stratmann ◽

Simon Medina ◽

Georg Jacobs ◽

Frank Mücklich ◽

...

Keyword(s):

Boundary Lubrication ◽

Surface Texturing ◽

Contact Stresses ◽

Laser Surface ◽

Laser Surface Texturing ◽

Wear Loss ◽

Textured Surface ◽

Periodic Patterns ◽

Rolling Bearings ◽

Fatigue Lifetime

AbstractLaser surface texturing (LST) has been proven to improve the tribological performance of machine elements. The micro-scale patterns manufactured by LST may act as lubricant reservoirs, thus supplying oil when encountering insufficient lubrication. However, not many studies have investigated the use of LST in the boundary lubrication regime, likely due to concerns of higher contact stresses that can occur with the increasing surface roughness. This study aims to examine the influence of LST on the fatigue lifetime of thrust rolling bearings under boundary lubrication. A series of periodic patterns were produced on the thrust rolling bearings, using two geometrically different designs, namely cross and dimple patterns. Base oil ISO VG 100 mixed with 0.05 wt% P of zinc dialkyldithiophosphate (ZDDP) was supplied. The bearings with cross patterns reduce the wear loss by two orders of magnitude. The patterns not only retain lubricant in the textured pockets but also enhance the formation of an anti-wear tribofilm. The tribofilm generation may be improved by the higher contact stresses that occur when using the textured surface. Therefore, in contrast to the negative concerns, the ball bearings with cross patterns were instead found to increase the fatigue life by a factor of three.

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