| 1. |
- Gomez-Gallegos, A. A., 1983-, et al.
(författare)
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A comparative study assessing the wear behaviour of different ceramic die materials during superplastic forming
- 2017
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley-VCH Verlagsgesellschaft. - 0933-5137 .- 1521-4052. ; 48:10, s. 983-992
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Tidskriftsartikel (refereegranskat)abstract
- Superplastic forming is an advanced manufacturing process where metallic sheets are heated to their superplastic region to be then blow formed within a die set. The process allows for the forming of complex parts but it is typically restricted to low volume production and high value pieces. Despite their brittle nature, ceramic dies are a developing technology for superplastic forming as they offer lower production costs and shorter lead times than conventional metallic dies, thus reducing process costs. This work presents a method to assess ceramic die wear by means of a novel test rig developed a at the Advance Forming Research Centre of the University of Strathclyde, Scotland, UK where the superplastic forming die-part interaction can be replicated at laboratory scale. Controllable normal load tests at standard superplastic forming conditions on three different reinforced ceramic materials are carried out with a view to understanding their wear mechanisms and to ultimately identify methods to improve their wear resistance.
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| 2. |
- Gudmundson, Peter, et al.
(författare)
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Die Werkstoffdämpfung von Stählen bei hohen Dehnungsamplituden
- 1986
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley. - 0933-5137 .- 1521-4052. ; 17:8, s. 286-292
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Tidskriftsartikel (refereegranskat)abstract
- Am Beispiel von zwei martensitischen Chromstählen (X 22 CrMoV 12 1, X 20 Cr 13) und eines kaltverformten Austeniten (X 12 CrNiWTi 16 13) wird die amplitudenabhängige Werkstoffdämpfung bei Raumtemperatur untersucht. Die martensitischen Werkstoffe weisen infolge der magneto-elastischen Effekte eine hohe amplitudenabhängige Dämpfung auf. Es kann gezeigt werden, daß eine Erhöhung der Festigkeit durch Absenken der Anlaßtemperatur zu einer Abnahme der Werkstoffdämpfung führt. Der untersuchte austenitische Werkstoff besitzt nach Kaltverformung eine beträchtliche Dämpfung, die jedoch beim Tempern bereits bei Temperaturen oberhalb von 100 °C auf die bei Austeniten üblichen tiefen Werte absinkt. Dieser Effekt wird der Verankerung der Versetzungen beim Tempern zugeschrieben. Damping of Steels at High Strain Amplitudes The amplitude dependent damping has been investigated in two martensitic chromium steels (X 22 CrMoV 12 1, X 20 Cr 13) and a cold worked austenitic steel (X 12 CrNiWTi 16 13) at room temperature. Due to the magneto-elastic effects, the martensitic steels show a strong amplitude dependent damping. It cound be shown that the damping is reduced remarkably by a reduction of the annealing temperature. The austenitic material shows a very high damping in the cold worked condition. Tempering at relatively low temperatures (above 100 °C) reduces damping to the low values usually expected for austenitic materials. This effect was attributed to the pinning of dislocations during tempering.
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| 3. |
- Kharitonov, D. S., et al.
(författare)
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Corrosion inhibition of AA6063 alloy by vanadates in alkaline media
- 2017
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley-VCH Verlagsgesellschaft. - 0933-5137 .- 1521-4052. ; 48:7, s. 646-660
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Tidskriftsartikel (refereegranskat)abstract
- Vanadium aqueous compounds are considered as promising environmentally friendly inhibitors for heterogeneous aluminium alloys. In this study, mechanism of corrosion inhibition of AA6063 in alkaline media by vanadate inhibitors is presented. A combination of weight loss and open circuit potential measurements, potentiodynamic polarization and electrochemical impedance spectroscopy was used to compare corrosion behavior of AA6063 alloy in aerated pH 10 0.05 M sodium chloride solutions in the absence and presence of 0.003 mol/l sodium orthovanadate. Tetrahedrally coordinated mono- and polyvanadates, that are main forms in such solutions, cause a decrease in corrosion current density and significantly increase amplitude of impedance spectra and impedance modulus |Z| values due to mixed cathodic-anodic inhibition effect mainly associated with the formation of adherent surface film on cathodic and anodic intermetallic particles of alloy.
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| 4. |
- Marquis, G. B., et al.
(författare)
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Fatigue improvement of welded steel joints by high frequency mechanical impact treatment
- 2015
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley. - 0933-5137 .- 1521-4052. ; 46:2, s. 136-144
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Tidskriftsartikel (refereegranskat)abstract
- The International Institute of Welding (IIW) technical working units provide unique forums for knowledge exchange to experts and professionals from industry, research institutes and world-leading universities. Developing science-based and industrially-relevant best practice guidelines is a key objective of these units. In the past decade, high frequency mechanical impact (HFMI) has significantly developed as a reliable, effective and user-friendly method for post-weld fatigue strength improvement technique for welded steel structures. The development of a new guideline for the design of structures improved using high frequency mechanical impact is presented. The extra fatigue strength benefit for high frequency mechanical impact treated high strength steels is also presented. Important issues like high frequency mechanical impact equipment, proper treatment procedures, operator safety, training, quality control measures and documentation are briefly discussed. Aspects of this guideline and the unique international nature of the IIW which has made it possible are described.
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| 5. |
- Olofsson, Anders, 1978-, et al.
(författare)
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Hardening Distortions of Serial Produced Crown Wheels
- 2017
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley-VCH Verlagsgesellschaft. - 0933-5137 .- 1521-4052.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The hardening distortions of serial produced crown wheels are studied with respect to gear runout, inner diameter and back-face tilt. The data analysed originates from a production data base from ordinary production as well as from directed experiments carried out in production, resulting in a large set of data. Strong influences are found for steel plants, position of material in ingots and stacking levels on hardening trays. It could be concluded that rectangular strands have a detrimental effect on gear runout, which, however, can be strongly decreased by disabling the magnetic stirring during casting. Furthermore, the inner diameter after quenching is influenced by the stacking level on the hardening tray when free-hardening or when using a segmented central expander during press quenching. This influence is attributed to variations in hardening temperature. When press quenching using a fixed mandrel, the effect of stacking level disappears. Moreover, it is found that the back-face tilt strongly depends on the position in the ingot as well as on the stacking level on the hardening tray.
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| 6. |
- Olofsson, A., et al.
(författare)
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Identifying process parameters influencing gear runout
- 2018
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : WILEY-V C H VERLAG GMBH. - 0933-5137 .- 1521-4052. ; 49:7, s. 859-869
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Tidskriftsartikel (refereegranskat)abstract
- The hardening distortions with respect to base body, clutch teeth and helical gears are investigated for a serial-produced main shaft gear of a 20NiCrMoS6-4 steel. The influences of casting geometry, annealing heat treatment and stress relief annealing of blanks, as well as vertical and horizontal loading arrangements during case hardening, are studied. The concentricity, roundness and runout of clutch teeth and helical gears are measured in the soft machined, hardened and hard-machined conditions. The Brinell hardness is measured on blanks obtained from different manufacturing routes showing differences in hardness and scatter. Stress relief annealing lowers the hardness and the scatter for all groups, but has no significant effect on distortions. The case depth, core hardness and surface hardness are measured after hardening. The study shows that the surface hardness correlates with the oil flow measured in the quench tank. The effect of casting geometry is stronger for the clutch teeth compared to the helical gears. For the clutch-teeth roundness and runout, significantly lower values are found for square geometry compared to rectangular. It is also seen that the major part of the runout comes from roundness errors which are mainly induced by the hardening. Horizontal loading reduces roundness errors and runout but produces conical base-bodies with worse backplane flatness.
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| 7. |
- Pålsson, Namurata, et al.
(författare)
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Corrosion behavior of zinc and copper coated structural steels in soil environments
- 2022
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : John Wiley and Sons Inc. - 0933-5137 .- 1521-4052. ; 53:1, s. 68-79
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Tidskriftsartikel (refereegranskat)abstract
- Corrosion behavior of structural carbon steels grade SS400 coated with copper and zinc exposed to soil sample extracted from the central part of Thailand is studied using weight loss analyses and electrochemical methods, including open circuit potential monitoring for 3600 seconds, electrochemical impedance spectroscopic analyses and potentiodynamic polarization measurements. Bare carbon steels are also examined as a reference. Open circuit potential and polarization resistance of all samples are measured on (1, 2, 3, 4, 7, 10, 15, 30, 45, 60, 77 and 91) days of exposure. Corrosion potential is monitored only on the first and last days. After 91 days, corrosion rate in millimeter per year is calculated from weight loss and corrosion product is characterized. Effects of coating material, thickness and process on corrosion resistance of carbon steel subjected to soil environment are reported and discussed.
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| 8. |
- Samuelsson, Jack, et al.
(författare)
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Service fatigue design of complex welded construction equipment
- 2008
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley. - 0933-5137 .- 1521-4052. ; 39:10, s. 734-739
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Tidskriftsartikel (refereegranskat)abstract
- Many steel structures and components are fabricated from steel plates and steel castings. The dominating joining method is welding for all kinds of transport vehicles and this paper describes briefly main problems in connection with design and fabrication of fatigue loaded structures. Design and fabrication has developed during the last 30 years and today we have tools, methods and knowledge to produce more optimised structures. Some of the work has been performed as joint work within Nordic projects and within IIW (International Institute of Welding). FE-modelling, improved design rules, knowledge about influence from defects and residual stresses, new manufacturing methods and scientific based weld quality rules are briefly discussed in this paper.
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| 9. |
- Sharma, D. K., et al.
(författare)
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Different reinforcement strategies of hybrid surface composite AA6061/(B4C+MoS2) produced by friction stir processing : Verschiedene Strategien beim Rührreibschweißen zur Verstärkung von Hybrid‐Oberflächenverbundwerkstoffen aus AA6061/(B4C+MoS2)
- 2020
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley-VCH Verlagsgesellschaft. - 0933-5137 .- 1521-4052. ; 51:11, s. 1493-1506
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Tidskriftsartikel (refereegranskat)abstract
- Aluminum surface composites have gained huge importance in material processing due to their noble tribological characteristics. The reinforcement of solid lubricant particles with hard ceramics further enriches the tribological characteristics of surface composites. In the current study, friction stir processing was chosen to synthesize hybrid surface composites of aluminum containing B4C and MoS2 particles with anticipated improved tribological behavior. B4C and MoS2 powder particles in 87.5: 12.5 ratio were reinforced into the AA6061 by hole and groove method. Microstructural observations indicated that reinforcement particles are well distributed in the matrix. The hardness and wear resistance of hybrid surface composites improved as compared to the base material, due to well distributed abrasive B4C and solid lubricant MoS2 particles in AA6061. The hybrid surface composites achieved ~32 % increased average hardness as compared to the base material. Hole method revealed ~13 % better wear resistance compared to the groove method for friction stir processed hybrid surface composite, attributing to an improved homogeneity of particle distribution shown by zigzag hole pattern. Moreover, friction stir processed AA6061 without reinforcement particles exhibited reduced hardness and wear resistance due to loss of strengthening precipitates during multi-pass friction stir processing. © 2020 Wiley-VCH GmbH
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| 10. |
- Sieber, Maximilian, et al.
(författare)
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Influence of anodic oxide coatings on screwing behaviour and susceptibility to stress corrosion cracking of self-tapping aluminium screws
- 2012
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : John Wiley & Sons. - 0933-5137 .- 1521-4052. ; 43:7, s. 661-667
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Tidskriftsartikel (refereegranskat)abstract
- Enhanced use of lightweight materials, namely aluminium and magnesium, requires the application of appropriate production techniques. Self-tapping screws represent an innovative joining technology. High-strength aluminium alloys can be used as screw material. Stringent requirements regarding the wear resistance of screw surfaces result from the thread-forming process. These requirements are met by oxide ceramic conversion layers produced by hard anodizing. Based on application-oriented testing methods, the influence of hard anodized layers on the screwing behaviour and susceptibility to stress corrosion cracking of high-strength aluminium screws is examined.
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| 11. |
- Stenberg, Thomas, et al.
(författare)
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Fatigue assessment of cut edges in high strength steel – Influence of surface quality
- 2017
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley-VCH Verlagsgesellschaft. - 0933-5137 .- 1521-4052. ; 48:6, s. 556-569
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Tidskriftsartikel (refereegranskat)abstract
- The influence of surface roughness on the fatigue strength in high strength steels and different cutting processes are studied. Fatigue testing is conducted on S700 and S960 material for different plate thicknesses cut in dog bone specimens using oxygen, plasma, laser and waterjet cutting. The surface roughness is measured for all specimens and residual stress measurements are carried out. Estimations of the fatigue strength are made based on the measured surface roughness and the ISO 9013:2002 standard for thermal cutting quality tolerances. The testing shows a 15–70 % increase in the fatigue strength compared to the estimation, proving a weak connection between the surface quality levels in ISO 9013:2002 and the fatigue test results. Different codes and design recommendations (IIW, EC3 and EN 13001) for fatigue strength of cut surfaces are compared with the fatigue test results which clearly shows an increased fatigue strength with enhanced quality and steel grades. However, the codes and design recommendations do not allow for any fatigue strength improvement with improved quality and increased yield strength.
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| 12. |
- Stiewe, C., et al.
(författare)
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Control of thermoelectric properties in ZrO2/CoSb3 nano-dispersed composites
- 2007
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley. - 0933-5137 .- 1521-4052. ; 38:9, s. 773-776
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Tidskriftsartikel (refereegranskat)abstract
- Nano-dispersed ZrO2/CoSb3 composites of various composition were prepared by uniaxial hot pressing of nano-sized powders of thermoelectric CoSb3 intermixed with ceramic nano-powders. The phase purity, the niicrostructure, and the temperature dependent transport parameters of the composites were investigated. Non-dispersed samples from nano-sized CoSb3 powders show higher electrical conductivity compared to melt-grown material which is attributed to the presence of a small excess of metallic Sb, but they exhibit lower thermal conductivity due to the fine-grained structure. Addition of 5 at.-% ZrO2 enhances the ratio of electrical to thermal conductivity, whereas hardly affects the See-beck coefficient. In this manner the nano-dispersion method provides an effective approach to improving the materials thermoelectric performance.
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| 13. |
- Walpole, Andrew R., et al.
(författare)
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Nano-porous Alumina Coatings for Improved Bone Implant Interfaces
- 2003
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley. - 0933-5137 .- 1521-4052. ; 34:12, s. 1064-1068
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Tidskriftsartikel (refereegranskat)abstract
- A new method is proposed for coating implants that produces a metal implant covered in a layer of nano-porous alumina ceramic. These layers are produced by first depositing a layer of aluminium on the implant surface and then anodising it in phosphoric acid to produce the nano-porous structure. This process results in the conversion of the aluminium to alumina containing 6-8wt% phosphate ions. The surface alumina layer is bonded to the substrate via an interfacial layer of fully dense anodised titanium oxide. Mechanical measurements have shown that the shear and tensile strength of this coating are in excess of 20MPa and 10MPa, respectively.The biological performance of nano-porous alumina material has been assessed and shown to be highly favourable, supporting normal osteoblastic activity and maintaining the osteoblastic phenotype. The filling of the nano-porous coating with bioactive material to achieve enhanced biological performance has been investigated using colloidal silica as an analogue for a Bioglass sol. The coating has been loaded with silica by dipping in colloidal silica with a pH of 5.6. Pore filling equivalent to 1.3 wt% SiO2 in the coating as a whole has been achieved in this way.
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| 14. |
- Zhu, Z., et al.
(författare)
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Cutting performance of cemented carbide cutting tool in turning high‐density fiberboard
- 2018
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : John Wiley & Sons. - 0933-5137 .- 1521-4052. ; 49:12, s. 1476-1484
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Tidskriftsartikel (refereegranskat)abstract
- In order to provide a scientific and reliable guidance for wood processing industry, the effects of cutting parameters on cutting forces, cutting temperature and tool wear were studied when turning high‐density fiberboard by use of cemented‐carbide cutting tools. The results showed that cutting forces (normal force and radial force) and cutting temperature are not affected by the cutting parameters in the same way: cutting forces decrease with increasing spindle speed, whereas cutting temperature increase with an increase of the spindle speed. However, there is a positive relation for cutting forces and temperature, to the feed per turn when cutting. The wear of the cemented‐carbide cutting tool is shown by two mechanisms: Mainly adhesive wear but also abrasive wear, showed by loss of carbide‐grains and by cracking and chipping, respectively. This study also indicated that higher‐speed cutting is beneficial for wood‐processing; evident by reduced energy for cutting and higher efficiency in production.
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| 15. |
- Goriachko, A., et al.
(författare)
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Hexagonal C and BN superstructures on Ru(0001) and Ge(111)
- 2013
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley. - 0933-5137. ; 44:2-3, s. 129-135
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Tidskriftsartikel (refereegranskat)abstract
- A brief overview of hexagonal superstructures with a periodicity of similar to 3 nm formed on Ru(0001) and Ge(111) by graphene or hexagonal boron nitride with a thickness of just a single atomic layer is given. A periodic height corrugation of such layers due to the lattice mismatch with the substrate material is of the order of 0.1 nm. Selected examples of scanning tunneling microscopy (STM) and low energy electron microscopy/diffraction (LEEM/LEED) investigations of BN/Ru(0001), C/Ru(0001), (BN)(x)C-y/Ru(0001) and C/Ge(111) are presented. These systems can act as nanotemplates for metal nanoparticles growth, as well as strongly heterogeneous substrates for molecular adsorption.
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| 16. |
- Ratswohl, Christoph, et al.
(författare)
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A design strategy to generate a SARS-CoV-2 RBD vaccine that abrogates ACE2 binding and improves neutralizing antibody responses
- 2023
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Ingår i: European Journal of Immunology. - 0014-2980 .- 1521-4141. ; 53:10
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Tidskriftsartikel (refereegranskat)abstract
- The structure-based design of antigens holds promise for developing vaccines with higher efficacy and improved safety profiles. We postulate that abrogation of host receptor interaction bears potential for the improvement of vaccines by preventing antigen-induced modification of receptor function as well as the displacement or masking of the immunogen. Antigen modifications may yet destroy epitopes crucial for antibody neutralization. Here, we present a methodology that integrates deep mutational scans to identify and score SARS-CoV-2 receptor binding domain variants that maintain immunogenicity, but lack interaction with the widely expressed host receptor. Single point mutations were scored in silico, validated in vitro, and applied in vivo. Our top-scoring variant receptor binding domain-G502E prevented spike-induced cell-to-cell fusion, receptor internalization, and improved neutralizing antibody responses by 3.3-fold in rabbit immunizations. We name our strategy BIBAX for body-inert, B-cell-activating vaccines, which in the future may be applied beyond SARS-CoV-2 for the improvement of vaccines by design.
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