Kenneth Holmberg

Kenneth Holmberg
VTT Technical Research Centre of Finland | vtt · Division of Applied Materials

Dr Techn

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163
Publications
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7,288
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Publications

Publications (163)
Article
Surface topography can affect the tribological performance in many applications. The influence of surface roughness and topographic orientation on friction and wear in dry and oil lubricated steel vs steel and diamond-like carbon (DLC) coated steel vs DLC coated steel sliding contacts was investigated. The surfaces had a centerline average roughnes...
Article
Full-text available
Diamond-like carbon (DLC) coatings have proven to be an excellent thin film solution for reducing friction of tribological systems as well as providing resistance to wear. These characteristics yield greater efficiency and longer lifetimes of tribological contacts with respect to surface solutions targeting for example automotive applications. Howe...
Article
A finite-element model for a paste lubricated steel wire vs cast iron contact was developed. The modelled contact included two surfaces with engineering topography and a paste lubricant. The paste lubricant consisted of a synthetic transmission oil, binder and solid manganese oxide particles. The purpose of adding solid particles in the lubricant w...
Conference Paper
For oxide coatings, prepared by applying plasma electrolytic oxidation (PEO) to aluminium alloy Al6082, this conference contribution presents the finite element (FE) microstructural modeling of the PEO coatings. By utilizing the coating phase maps, obtained by electron back-scattered diffraction (EBSD) technique, the corresponding images have been...
Article
Full-text available
Roughness and curvature of diamond-like carbon (DLC) surface coatings change with both scale and direction of a measurement. However, the changes are not detected by currently used standard parameters which are designed to work with isotropic surfaces at a single scale, thus providing only a limited information about multiscale and directional roug...
Article
Full-text available
In total, ~23% (119 EJ) of the world’s total energy consumption originates from tribological contacts. Of that 20% (103 EJ) is used to overcome friction and 3% (16 EJ) is used to remanufacture worn parts and spare equipment due to wear and wear-related failures.
Article
Full-text available
Calculations on the global energy consumption due to friction and wear in the mineral mining industry are presented. For the first time, the impact of wear is also included in more detailed calculations in order to show its enormous tribological and economic impacts on this industry. A large variety of mining equipment used for the extraction, haul...
Article
Diamond-like carbon (DLC) coated surfaces exhibit anisotropic and multi-scale characteristics, i.e., their roughness change with both scale and direction. However, most currently used standard surface characterisation parameters and methods work well only with isotropic surfaces at a single scale. This problem can be overcome by variance orientatio...
Article
The effects of surface roughness and topographical orientation on surface stresses influencing wear have been investigated for diamond like carbon (DLC) coated steel surfaces with three levels of surface roughness in the range of 0.004–0.11 μm Ra values, and with topographical groove orientations of 0°, 45° and 90°. A novel multiscale numerical fin...
Article
Full-text available
TiN and diamond-like carbon (DLC) coatings were deposited on Ti substrates with and without processing by high-pressure torsion (HPT). The HPT processing refined the grain size of titanium from the coarse-grained (CG) size of ~8.6 µm to the ultra-fine grained (UFG) size of ~130 nm and increased the hardness from ~1.83 to ~3.05 GPa. Scratch test res...
Article
Full-text available
Interface structures are a key feature in developing modern composite material solutions with ever improved performance. We present a nano-microstructural modelling approach for the tungsten carbide (WC)–Co system which can include the interface structures of WC–Co and various other phases present in the microstructure, utilising a methodology whic...
Article
Full-text available
This paper studies failure of birch pulp–polylactic acid composites. Stiffness and strength are calculated using the theory of short fibre composites and the results are compared to experimental data. The results differed from the experimental values by 0–6%. With less aligned fibres the short fibre theory is not feasible. The performance of the 40...
Article
The present work describes the wear behaviour of nodular cast iron in rolling–sliding contact with steel wire ropes and steel wires in laboratory and in-service conditions. In each of the studied examples, the wear had proceeded through a surface fatigue process, in which inter-nodular crack propagation and simultaneous deformation in a thin sub-su...
Article
The effect of surface roughness and topographical orientation on friction and wear has been investigated for diamond like carbon (DLC) coated and uncoated steel surfaces with three levels of surface roughness in the range of 0.004 – 0.11 μm Ra value and with topographical orientations at 0°, 45° and 90° angles from grinding marks. In this first par...
Article
Full-text available
High velocity solid particle erosion may cause severe damage and high wear rates in materials used for wear protection. An experimental work on the behavior of wear resistant steels, including three high- strength martensitic alloys and a carbide-reinforced metal matrix composite, was performed in high rate single impact conditions. Characterizatio...
Article
The deformation and wear behavior of four high strength wear resistant steels were studied in various impact conditions to evaluate their performance in applications involving heavy impacts and impact-abrasion. In the normal direction impacts, the studies were conducted with single and repeated (multiple) drop tests. To better simulate the actual a...
Article
Full-text available
The alloying of Hadfield steels aims at enhanced mechanical properties and improvements in the wear resistance. In this work, the impact and abrasive properties of a chromium-alloyed high-manganese Hadfield steel were experimentally studied using a wide variety of testing techniques and characterization methods. In addition, an in-service sample wa...
Article
Worldwide about 100 million terajoule is used annually to overcome friction and that is one fifth of all energy produced. The largest quantities of energy are used by industry (29 %) and in transportation (27 %). Based on our recent studies on energy use in passenger cars, trucks and buses, we concluded that it is possible to save as much as 17.5 %...
Article
During the past two decades, global awareness and societal needs for more fuel-efficient and environmentally friendly transportation systems have increased considerably because of the diminishing oil reserves, skyrocketing fuel prices, and much tougher governmental regulations to combat greenhouse gas emissions. During the same period, automotive a...
Article
In this study, the effect of operational conditions (normal load, sliding velocity) and environment (pH and ionic strength) on the lubrication properties of two different hydrophobin proteins were investigated using pin on disc tribometry and ellipsometry. The studied proteins were wild type HFBI and the glycosylated hydrophobin FpHYD5. It was obse...
Article
High strength steels (HSS) used in highly abrasive environments, such as in mining and crushing, must endure high stress abrasion. To properly understand the wear behavior of materials under such circumstances, the connection between surface loading, work hardening, and material removal has first to be determined. In this study, wear resistant stee...
Article
The mucilage, originating from the seeds of quince fruit was characterized as a potential bio-inspired water-based lubricant. The mucilage consists mainly of fine cellulose nanofibrils and charged hemicelluloses whose structure and properties were characterized here by atomic force microscopy (AFM) and tribological Pin-On-Disc (POD) experiments. Th...
Chapter
This chapter discusses the possibilities that the rapidly developing deposition techniques, such as physical and chemical vapour deposition, offer to change the tribological properties by applying very thin hard or soft surface coatings. The wear and friction mechanisms are described on the macro-, micro- and nanoscale and their effect is discussed...
Article
The wear resistance of components can be changed remarkably by surface coatings. New processing methods offer many possibilities to tailor the wear resistance of surfaces to match design criteria. Computational modelling and simulation is a systematic approach to optimise the wear performance. Modelling of physical surface phenomena can be carried...
Article
Evaluation of wear mechanisms of thick thermal sprayed cermet coatings is a challenging endeavor given the numerous process-induced structural and chemical changes as well as presence of residual stresses. In an effort to understand the damage processes under contact load and their sensitivity to process induced microstructural attributes, controll...
Article
A computational modelling and simulation approach was developed and applied for wear resistance analysis of composite coatings. Three new numerical finite element models were developed to include microstructural properties of typical thick thermal spray and laser cladded metal matrix coatings. The first was an ideal synthetic defect free material m...
Article
Surface coatings are increasingly used to improve the tribological performance of advanced products. The novel coating deposition techniques offer numerous possibilities for tailoring surfaces with different materials and structures. The tribological contact of loaded surfaces is, however, a complicated system itself, and further complexity is intr...
Article
The present work describes the major findings of a wear mechanism analysis based on optical and scanning electron microscopy on rollers made from nodular cast iron that had rolled under partial slip against steel wire ropes in field service and in wear tests using rollers and wire ropes. Various wear modes were identified on the wire rope groove su...
Article
Calculations on the global energy consumption used to overcome friction in paper machines in terms of friction in motors, transmissions, pumps, blowers, agitators, pipes and the roll systems are presented. The following was concluded:–The energy consumed to overcome friction in a paper mill is in the range 15–25%.–Globally there were 8525 paper and...
Article
The influence of a pre-existing crack field on coating adhesion failure in a steel surface coated with a 2 μm thick titanium nitride (TiN) coating was investigated by finite element method modelling and simulation. The stress and strain fields were determined in contact conditions with a spherical diamond tip sliding over the coated surface at a lo...
Article
Laser cladded coatings have been used extensively to extend the service life of components exposed to severe abrasive wear. One of the main wear resistant materials used in laser cladding is ceramic–metallic composite. Despite extensive use of this class of material, there is very limited knowledge regarding mechanical degradation mechanisms, such...
Article
Full-text available
Macroscale tribological properties of hydrophobin layers bound on stainless steel surfaces were investigated in an aqueous environment. Emphasis was on boundary lubrication because water easily fails in hydrodynamic lubrication due to its low viscosity. We studied the affinities of two different proteins, HFBI and FpHYD5, on stainless steel and the...
Conference Paper
Complexity in dynamics of super sonic flame formation mechanisms and effects of processing variables has made the understanding of interaction of particles and flame a difficult task. Lack of such understanding limits the possibilities of controlling the process to obtain desired in-flight particles temperature and velocity and consequent particles...
Article
This study presents calculations on the global fuel energy consumption used to overcome friction in passenger cars in terms of friction in the engine, transmission, tires, and brakes. Friction in tribocontacts was estimated according to prevailing contact mechanisms such as elastohydrodynamic, hydrodynamic, mixed, and boundary lubrication. Coeffici...
Article
DLC films cover a wide range of different carbon based coatings, starting from soft to extremely hard diamond-like carbon films. In this study two different types of DLC films have been studied in respect of their stress and strain characteristics and tribological performance. The coatings are hydrogenated amorphous carbon (a-C:H) coatings deposite...
Article
The aim of this study is to find a connection between mechanical engineering and biotechnology by utilizing biomimetics in lubrication. The objective is to improve boundary lubrication by biomolecules in water-based systems. Proteins were used because they can form films and multilayers on the surfaces and thus prevent direct contact between them....
Article
Full-text available
This chapter outlines the work done in Dynamite project (http://DYNAMITE.vtt.fi), as well as the resulting concept nicknamed as DynaWeb. DynaWeb represents the link between Dynamite and the e-maintenance technologies described in previous chapters and results in a global framework where all technologies can participate within an advanced maintenanc...
Chapter
Maintenance has developed during the last half century from a low-tech “repair and lubrication man” circulating on the shop floor, to a truly high-tech, scientifically based, multidisciplinary field of technology that is of strategic importance in industrial plants, transportation and power production. Maintenance today means the technological-econ...
Book
E-maintenance is the synthesis of two major trends in today's society: the growing importance of maintenance as a key technology and the rapid development of information and communication technology. E-maintenance gives the reader an overview of the possibilities offered by new and advanced information and communication technology to achieve effici...
Article
Full-text available
E-maintenance, Kenneth Holmberg, Adam Adgar, Aitor Arnaiz, Erkki Jantunen, Julien Mascolo and Samir Mekid (eds.), 5-37 This chapter describes the state of the art in maintenance and its future trends. The key areas which have influenced maintenance in the last forty years are management of people and assets, and technological capability. These area...
Article
Full-text available
Thin hard coatings on components and tools are used increasingly due to the rapid development in deposition techniques, tribological performance and application skills. The residual stresses in a coated surface are crucial for its tribological performance. Compressive residual stresses in PVD deposited TiN and DLC coatings were measured to be in th...
Article
Thin hard coatings in the thickness range of only a few micrometers deposited by physical vapour deposition (PVD) on components or tools can improve the friction and wear properties by several orders of magnitude. A 2 μm thick TiN (E=300 GPa) coating on a high-speed steel substrate with a bond layer at the interface between the coating and the subs...
Article
VTT researchers have been pioneers in international science with their computer modelling and simulation techniques for the development of coated surfaces with superior wear resistance and low friction properties. They have introduced a novel PPSP (Performance-Properties-Structure-Processing) multi-scale concept that is based on linking wear and fr...
Article
The recent scientific development and technical innovations have opened new possibilities to reduce friction and wear in some applications even with several orders of magnitude. The rapidly increasing computer capacity, the new material modeling tools and the improved micro- and nanolevel characterization techniques makes it possible to perform com...
Article
A prognosis of the machinery condition is an important potential tool to avoid unpredictable and expensive disturbances, failure and shut down in industrial production and transportation. A diagnosis of machinery condition can be carried out based on online condition monitoring. The prediction of future performance needs, in addition to knowledge o...
Article
Surface coatings, like titanium nitride (TiN) and diamond-like carbon (DLC) coatings, offer high wear resistance and good friction performance for a wide range of applications. With novel advanced techniques like modelling and simulation, the performance of these coatings can be predicted under a wide range of loading conditions. This provides valu...
Article
Diamond-like carbon (DLC) coatings have low friction and high wear resistance compared to bulk materials and to other wear-resistant coated surfaces. The surrounding environment, gas atmosphere, humidity and temperature, affect the friction and wear performance of DLC films dramatically. In dry and inert atmospheres, the highly hydrogenated DLC fil...
Article
Full-text available
Coating a surface with a thin layer changes the surface material properties and is an important tool for controlling friction and wear. The tribological mechanisms, scale effects and parameters influencing the friction and wear of coated surfaces are discussed. The basic friction and wear mechanisms can be reduced to: friction by adhesion, ploughin...
Article
Full-text available
Stress and strain modelling and stress field computer simulations are today an important tool for systematic approach and optimisation of tribologically stressed coated contacts. Modelling illustrates and quantifies the dominating parameters resulting in crack initiation, crack growth and failure of coated surfaces. Friction and its components, adh...
Article
Full-text available
This paper, which forms part of a special issue of this journal marking a 25th year anniversary in tribology, aims to provide an appraisal of key issues in coating tribology over that period. Two main inter-related strands are emphasized. One is the continuing move down the length scale in terms of the fundamental understanding of tribological cont...
Article
A tribological analysis of deformations and stresses generated and their influence on crack generation and surface fracture in a coated surface loaded by a sliding sphere in dry conditions is presented. A three-dimensional finite element method (3D FEM) model has been developed for calculating the first principal stress distribution in the scratch...
Article
Full-text available
The stress and fracture conditions of a coated surface, that are the origin to wear, were analysed by three-dimensional finite element method (FEM) modelling on microlevel, by stress and strain computer simulations and by experimental studies with a scratch tester. The studied tribological contact was a 0.2 mm radius diamond ball sliding with incre...
Article
Full-text available
The surface fracture mechanisms, that are the origin to wear, were analysed by three-dimensional finite element method (FEM) modelling on micro-level by stress and strain computer simulations and by experimental studies with a scratch tester. The studied tribological contact was a diamond ball sliding with increasing load on a thin titanium nitride...
Article
Surface coatings, like titanium nitride (TiN) and diamond-like carbon (DLC) coatings offer high wear resistance and low friction performance for a wide range of applications. By using new techniques such as modeling and simulation, the coating performance under load can be estimated and thus provide valuable information for the coating design and f...
Article
Full-text available
Material deformations and the influence of coating thickness and elastic modulus were analysed by three-dimensional finite element method (FEM) modelling on microlevel, by stress, strain, and displacement computer simulations and by experimental studies with a scratch tester. The studied tribological contact was a diamond ball sliding with increasi...
Conference Paper
A general approach to controlling and modelling friction and wear in sliding contacts with coated surfaces is presented. The tribological aspects of the main material parameters, elasticity, plasticity and fracture are discussed. The contact condition with a rigid sphere sliding over a steel plate coated with a very thin hard coating is analyzed. T...
Article
The fundamentals of coating tribology is presented in a generalised holistic approach to friction and wear mechanisms of coated surfaces in dry sliding contacts. It is based on a classification of the tribological contact process into macromechanical, micromechanical, tribochemical contact mechanisms and material transfer. The tribological contact...