| 1. |
- André, Benny, et al.
(författare)
-
Performance and Tribofilm Formation of a Low-Friction Coating Incorporating Inorganic Fullerene Like Nano-Particles
- 2012
-
Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 206:8-9, s. 2325-2329
-
Tidskriftsartikel (refereegranskat)abstract
- A new tribological coating with potential as a coating for components for low-friction applications is tested and compared to three, state of the art, commercial low-friction PVD coatings. The new coating is an electrodeposited coating composed by a Ni-P matrix incorporating fullerene like nanoparticles of WS2. The performance of the new coating is compared with three reference coatings in a ball-on-disc setup. The tribological tests involved ball bearing steel balls slid on coated discs, under different conditions of humidity and also with or without oil lubrication. Both mating surfaces were closely investigated in a scanning electron microscope and the low-friction tribofilms formed were further analysed. The correlations found between coefficient of friction, surface roughness of the wear scar, tribofilm formation and contact conditions are discussed. The new coating exhibits a very low coefficient of friction at low humidity, a behaviour closely resembling that of the MoS2-based commercial reference, whereas the carbon based PVD coatings tested exhibit the reversed dependence of humidity. The low-friction behaviour of the new coating is correlated to the formation of a WS2 tribofilm with a superficial alignment of the basal planes parallel to the sliding direction. When lubricated with a base oil, the beneficial tribofilm is not formed and the coefficient of friction is much higher. The results show that even though the coating is an electrodeposited coating it can compete with state of the art commercial PVD coatings.
|
|
| 2. |
- Gustavsson, Fredrik, 1977-, et al.
(författare)
-
Nanoparticle based and sputtered WS2 low-friction coatings : differences and similarities with respect to friction mechanisms and tribofilm formation
- 2013
-
Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 232, s. 616-626
-
Tidskriftsartikel (refereegranskat)abstract
- MoS2 and WS2 are widely known intrinsic low-friction materials that have been extensively used and thoroughly investigated in literature. They are commonly produced in the form of sputtered coatings and show extremely low friction coefficients in non-humid environments, but rapidly degrade in humid conditions. Close nested fullerene-like nanoparticles of these materials have been proposed to have better oxidation resistance due to their closed form with the absence of dangling bonds. In the present study, an electrochemically deposited coating consisting of fullerene-like nanoparticles of WS2 embedded in a Ni-P matrix is tested under various loads and humidity conditions and compared with a sputtered WS2 coating with respect to their tribological behavior. The formation of a tribofilm on both surfaces is known to be crucial for the low-friction mechanism of WS2 and the different mechanisms behind this formation for the two types of coatings are investigated. It is shown that despite the completely different transformation processes, the resulting tribofilms are very similar. This is analyzed thoroughly using SEM, AES and TEM. The friction coefficient is known to be lower at higher normal loads for these materials and in the present study the mechanical and chemical responses of the tribofilm to higher normal loads during sliding are investigated. It was observed that the basal planes become aligned more parallel to the surface at higher loads, and that the tribofilm is less oxidized. It is suggested that these mechanisms are connected and are crucial keys to the wear life of these materials. (C) 2013 Elsevier B.V. All rights reserved.
|
|
| 3. |
|
|
| 4. |
- Henfridsson, Ola, 1970, et al.
(författare)
-
Managing technological change in the digital age: the role of architectural frames
- 2014
-
Ingår i: Journal of Information Technology. - : SAGE Publications. - 0268-3962 .- 1466-4437. ; 29:1, s. 27-43
-
Tidskriftsartikel (refereegranskat)abstract
- Inspired by Herbert Simon's notion of nearly decomposable systems, researchers have examined modularity as a powerful approach to manage technological change in product innovation. We articulate this approach as the hierarchy-of-parts architecture and explain how it emphasizes decomposition of a design into loosely coupled parts and subsequent aggregation of these into an industrial product. To realize the scale benefits of modularity, firms successively freeze design specifications before production and therefore only allow limited windows of functionality design and redesign. This makes it difficult to take advantage of the increased speed by which digitized products can be developed and modified. To address this problem, we draw on Christopher Alexander's notion of design patterns to introduce a complementary approach to manage technological change that is resilient to digital technology. We articulate this approach as the network-of-patterns architecture and explain how it emphasizes generalization of ideas into patterns and subsequent specialization of patterns for different design purposes. In response to the increased digitization of industrial products, we demonstrate the value of complementing hierarchy-of-parts thinking with network-of-patterns thinking through a case study of infotainment architecture at an automaker. As a result, we contribute to the literature on managing products in the digital age: we highlight the properties of digital technology that increase the speed by which digitized products can be redesigned; we offer the notion of architectural frames and propose hierarchy-of-parts and network-of-patterns as frames to support innovation of digitized products; and, we outline an agenda for future research that reconsiders the work of Simon and Alexander as well as their followers to address key challenges in innovating digitized products.
|
|
| 5. |
- Jenei, István Zoltán, et al.
(författare)
-
Correlation Studies of WS2 Fullerene-Like Nanoparticles Enhanced Tribofilms : A Scanning Electron Microscopy Analysis
- 2013
-
Ingår i: Tribology letters. - : Springer Science and Business Media LLC. - 1023-8883 .- 1573-2711. ; 51:3, s. 461-468
-
Tidskriftsartikel (refereegranskat)abstract
- The beneficiary effects of tungsten disulphide (WS2) inorganic fullerene-like nanoparticles (IFLNPs) in the lubrication industry were shown in recent years. However, their successful incorporation into lubricants (oils, greases) is not straightforward. In practice, the lubricant contains several components for different purposes, e.g. reducing the oxidization of the oil (antioxidant), minimizing the wear rate (anti-wear additive), dispersants, etc. These additives can contain chemically active compounds, which under the lubrication process (where locally extreme conditions can develop: high pressure and flash temperatures) can change the chemistry in the contact zone and block the beneficial effects of the inorganic nanoparticles. In this investigation, poly-alpha-olefin (PAO) is being used as base oil in which the WS2 nanoparticles and different additives are mixed. A ball-on-disc sliding test revealed that certain additives inhibit the nanoparticles to reduce friction (less than 5 % decrease in friction coefficient), while in other cases, the friction reduction was above 50 %. The comparison is being made between PAO + additive and PAO + additive + IFLNPs. Scanning electron microscope and energy dispersive X-ray spectroscopy were used to investigate the elemental composition of the tribofilms formed on the wear marks. Further analysis was made in order to reveal correlations between elemental compositions of the tribofilms and external parameters such as the friction coefficient and wear rate. For instance, a strong correlation between tungsten content of the tribofilm and the friction coefficient was found.
|
|
| 6. |
|
|
| 7. |
- Selander, Lisen, 1979, et al.
(författare)
-
Capability Search and Redeem Across Digital Ecosystems
- 2013
-
Ingår i: Journal of Information Technology. - : SAGE Publications. - 0268-3962 .- 1466-4437. ; 3:28, s. 183-197
-
Tidskriftsartikel (refereegranskat)abstract
- Prior research on digital ecosystems focuses on the focal firm (e.g., a platform owner) and its ecosystem governance. However, there is a dearth of literature examining the non-focal actor, that is, an ecosystem participant who is at the periphery of a digital ecosystem. This paper proposes a theoretical perspective of the non-focal firm's participation across digital ecosystems for cultivating its innovation habitat through capability search and redeem. Capability search involves the location of external capability deemed valuable for extending the firm's innovation habitat. Capability redeem refers to the firm's use of external capability to develop, distribute, and/or monetize its products and services. We generate and sensitize the proposed perspective in the context of Sony Ericsson's innovation habitat by interpreting the mobile device manufacturer's participation across four digital ecosystems (Visual Basic, Java, Digital Music, and Android). Our findings suggest that the non-focal actor cannot rely on a single ecosystem for addressing all relevant layers of innovation. It benefits from pursuing a pluralistic strategy, operating across digital ecosystems to avoid investing all efforts in the same ecosystem. The model of ecosystem capability search and redeem, which is a result of ideographic research explanation, extends current perspectives on digital ecosystems and contributes to the emerging literature in the digital age.
|
|
| 8. |
|
|
| 9. |
- Svahn, Fredrik, 1972-
(författare)
-
Digital Product Innovation : Building Generative Capability through Architectural Frames
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Over the last decades we have witnessed a profound digitalization of tangible products. While this shift offers great opportunities, it also exposes product developing industries to significant challenges. In these industries organizations, markets, and technologies are tuned for mass production, providing competitive advantage through scale economics. Typically, firms exercise modular strategies to deliver such scale benefits. Rooted in Herbert Simon’s notion of near decomposability, modular product architectures allow for production assets, such as tools, processes, and plants, to be effectively reused across product variants and over generations of designs. However, they come at a price; modularity requires overall design specifications to be frozen well before production. In practice, this tends to inscribe functional purpose in the structures of the system, effectively preventing firms from taking advantage of the speed by which digitized products can be developed and modified.The main objective of this thesis is to investigate and explain how product developing organizations adapt architectural thinking to balance the proven benefits of modularity and the emerging opportunities provided by digital technology. In doing so, it introduces a complementary architectural frame, grounded in Christopher Alexander’s seminal work on patterns. This frame associates the concept of architecture with generativity and reuse of ideas, rather than scale economics and reuse of physical assets.Sensitizing the theoretical framework through a longitudinal case study of digital product innovation this thesis derives several implications for theory and practice. Across four embedded cases in the automotive industry it demonstrates that generative capability follows from a shared organizational view on products as enablers and catalyzers of new, yet unknown functionality. Such an emergence-centric view requires product developing firms to rethink existing governance models. Rather than exercising control through specific functionality, inscribed in modular product structures, it offers the benefit of influencing innovation through general functional patterns, serving as raw material in distributed and largely uncoordinated innovation processes. This shift in focus, from specific functionality to general functional patterns, enables a new strategic asset for product developing firms. It opens up for proactive rather than reactive strategies, where the architecture makes an instrument to cultivate new ideas and business opportunities, rather than a tool for cost savings.
|
|
| 10. |
- Svahn, Fredrik, et al.
(författare)
-
Formation of Low-Friction Particle/Polymer Composite Tribofilms by Tribopolymerization
- 2011
-
Ingår i: Tribology letters. - : Springer Science and Business Media LLC. - 1023-8883 .- 1573-2711. ; 41:2, s. 387-393
-
Tidskriftsartikel (refereegranskat)abstract
- Inorganic fullerene-like (IF) solid lubricant particles based on MoS(2) or WS(2) have recently gained attention in various tribological applications, for instance incorporated in coatings, porous materials, greases and dispersed in oils. However, their effect in oil can be limited often due to inadequate penetration into the contact zone. Meanwhile, tribopolymerization of monomer additives in oil have proven to be efficient to reduce wear, but without significantly reducing the friction. This investigation combines these two lubrication techniques in order to form particle/polymer composite tribofilms, aimed to give low friction and wear in high-pressure sliding contacts. A cyclic amine, caprolactam, was used as the monomer together with IF as well as normal 2H WS(2) particles. Zn-DTP was used as a reference antiwear additive and poly-alfa-olefin (PAO) was used as the base oil. Reciprocal ball-on-flat sliding test results found that monomer plus particles reduced the friction by 10-50%, depending on sliding speed and type of particles, compared with particles or monomer alone. And the scattering between different tests was also considerably lower. The wear rate was also substantially reduced to a level similar to that of Zn-DTP. The particle/polymer composite tribofilms were generally much larger than the actual contact area and its thickness varied from below a few nanometres in the contact centre to several micrometers in the outer parts. Consequently, the reduced friction is believed to come from two effects: one being a trapping of particles in the contact zone, which reduces the boundary friction level; and the other a shift in lubrication regime towards EHD-lubrication due to reduced contact pressures accompanied with the formation of the composite tribofilm.
|
|
