A novel texturing of micro injection moulding tools by applying an amorphous hydrogenated carbon coating

Griffiths, Christian; Dimov, Stefan Simeonov; Rees, Andrew; Delléa, O.; Lacan, Franck; Hirshy, Hassan

doi:10.1016/j.surfcoat.2013.07.006

Cited by 17 publications

(15 citation statements)

References 41 publications

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“…Additional validation was also carried out by simulating the growth of a-C films using the atom-by-atom deposition approach, and the corresponding results revealed that the ReaxFF 23 potential used in the present work could accurately describe the density, residual stress, hybridized structure, bond angles, and length distributions of the a-C structures through comparison with the widely accepted AIREBO potential 31 (manuscript under preparation). During the friction process, a three-step process was adopted ( Figure S6): (i) geometric optimization (GO) at 300 K for 2.5 ps, (ii) a loading process to achieve the specified value of contact pressure (5,20, and 50 GPa) during 25 ps, and (iii) a sliding process with a fixed contact pressure (5-50 GPa) and sliding velocity (10 m/s) along the x-direction for 1250 ps. A high contact pressure, such as 50 GPa, was possible for the instantaneous contact of a-C asperities during the friction process.…”

Section: Methodsmentioning

confidence: 99%

“…In recent years, amorphous carbon (a-C) films have become increasingly popular in both the scientific and engineering communities because of their impressive combination of high hardness, low friction coefficient, and chemical inertness. [1][2][3][4] These properties can provide effective protection against serious mechanical or chemical damage of moving mechanical components, such as tools, 5 automobile engines, 6 aerospace components, 7 and artificial joints. 8,9 However, a-C films inevitably undergo self-consumption, which severely limits their lifetime and reliability and ultimately leads to the catastrophic failure of the coated surface.…”

Section: Introductionmentioning

confidence: 99%

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Mechanism of contact pressure-induced friction at the amorphous carbon/alpha olefin interface

Wang

Lee

2018

npj Comput Mater

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Combining an amorphous carbon (a-C) film with a lubricating oil can significantly improve the friction performance and lifetime of moving mechanical components. However, the friction mechanism is not well understood owing to a lack of information regarding the structure of the interface when exposed to high contact pressure. Here, we select linear alpha olefin, C 5 H 10 , as a lubricant and study the evolution of the structure of the a-C/C 5 H 10 /a-C sliding interface under contact pressure via reactive molecular dynamics simulation. Our results suggest that introducing C 5 H 10 into the a-C/a-C interface reduces the friction coefficient by up to 93% compared with no lubricant, although the lubricating efficiency strongly depends on the contact pressure. In particular, increasing the contact pressure not only induces the binding of the lubricant with a-C, but also facilitates the dissociation of the C 5 H 10 carboncarbon skeleton by specific scissions, which governs the friction behavior. These results disclose the underlying lubrication mechanism and could enable the development of new and effective lubricating systems with long lifetimes.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanism of contact pressure-induced friction at the amorphous carbon/alpha olefin interface

Wang

Lee

2018

npj Comput Mater

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“…Additionally, due to DLC's lubricating properties and low surface roughness, the ejection forces in microinjection moulding of components with large area to volume ratios surfaces can be decreased significantly [9]. Also, the same effect was observed on DLC-coated mould tools with sub-micron textures (nano bead-like features and nanopillars fabricated by photolithography) and this was explained with the low coefficient of friction (CoF) as a dominant factor in achieving low demoulding forces [10]. It is worth noting that these investigations were conducted using relatively thick DLC coatings up to 5 µm, which were applied on completely machined moulds and thus their properties remained intact.…”

Section: Introductionmentioning

confidence: 83%

Sub-micron structuring/texturing of diamond-like carbon-coated replication masters with a femtosecond laser

Michalek

Batal

et al. 2020

Appl. Phys. A

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Diamond-like carbon (DLC) coatings have very attractive mechanical and tribological properties, i.e. high hardness, low friction and high wear resistance. Therefore, DLC is often used as a solid lubricant in moulds for injection moulding. Laser processing of DLC with ultrashort lasers, i.e. femtosecond lasers, can be performed both at micron and sub-micron scales, namely by producing laser-induced periodic surface structures (LIPSS). In this research, the effects of laser structuring/ texturing on DLC properties are investigated. First, the laser-processing parameters were optimised to produce uniform LIPSS without damaging a thin DLC film and then the properties of the textured DLC-coated substrates were studied. It was determined that the tribological properties of the processed surfaces remained unchanged, but the hardness of the structured/ textured DLC layers was reduced significantly. Although GAXRD and Raman spectroscopy did not show any significant crystallisation of the DLC coating after the laser irradiation, the analysis indicated that a thin graphitised layer had been formed on the surface as a result of the femtosecond laser processing.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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“…aC:H coatings are most commonly used for coatings of plastic injection moulding inserts [24]. The coatings have been proven to improve the repeatability of the micro and nano-structured master inserts [17].…”

Section: Coated Surfacesmentioning

confidence: 99%

Investigation of the Integrity of aC:H Coatings on Stainless Steel Micro-Moulds during Thermal Cycling

Griffiths

Rees

Llewelyn

et al. 2018

J. Coat. Sci. Technol.

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Micro-injection moulding (µIM) is a key technology for scaling down larger geometry components and can include functional features at the micrometre scale and as far as the sub-micrometre length scale. Thermal cycling of amorphous hydrogenated carbon (aC:H) coated Stainless Steel (SS) has been investigated to simulate long-term micro-injection moulding (µIM) wearing and damage. Micro indentations and cracks were made into the mould and predictions of the crack behaviour were made using thermal expansion models. Validation of the results was performed with multiple heating and cooling cycles along with hardness measurements of the damage to the coating. The undamaged surfaces showed no major deformation but the cracks were shown to propagate and change in behaviour. The first two heat cycles of the testing had the most significant effect on the substrate with varying thermal expansions of materials being the main cause. The aC:H is shown to have excellent properties for mould tool applications but delamination could occur in areas susceptible to damaged and periodic surface inspection will be required preserve tool life.

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A novel texturing of micro injection moulding tools by applying an amorphous hydrogenated carbon coating

Cited by 17 publications

References 41 publications

Mechanism of contact pressure-induced friction at the amorphous carbon/alpha olefin interface

Mechanism of contact pressure-induced friction at the amorphous carbon/alpha olefin interface

Sub-micron structuring/texturing of diamond-like carbon-coated replication masters with a femtosecond laser

Investigation of the Integrity of aC:H Coatings on Stainless Steel Micro-Moulds during Thermal Cycling

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