Showing papers by "Andrej Atrens published in 2022"

Design, mechanical and degradation requirements of biodegradable metal mesh for pelvic floor reconstruction.

Abstract: Pelvic organ prolapse is the herniation of surrounding tissue and organs into the vagina and/or rectum and is a result of the weakening of pelvic floor muscles, connective tissue, and fascia. It is widely accepted that 50% of women will develop prolapse, with the prevalence increasing with age, and up to 10-20% of those seek evaluation for their condition. Suture repairs of pelvic floor defects are associated with a high failure rate, and permanent meshes were introduced to reduce the recurrence rate. The meshes were successful in reducing the rate of recurrence but were also associated with a higher rate of complications (pain or erosion into surrounding organs) and as such have been banned in many countries. New materials that are able to provide tissue support without complications are urgently required. A promising new material may be a biodegradable metal, which provides support during healing and subsequently completely degrades. We summarise pelvic mesh usage, and evaluate the use of a biodegradable metal, which has advantages of biocompatibility, antibacterial properties, and mechanical properties. The remaining challenges are discussed as follows: (1) degradation rate, (2) stiffness, (3) corrosion fatigue, (4) zinc aging, and (5) MRI artifacts.

A novel dissolution-precipitation mechanism during liquid phase sintering and its strengthening effects in W-Ni-Fe alloys with low W contents

Abstract: W-Ni-Fe alloys with a low W content are a kind of promising tungsten alloys. However, limited results are available, and the responsible mechanism is not known for their dissolution-precipitation behavior, because long-range migration under the low W concentration is difficult after tungsten dissolution. In this work, a tungsten alloy with a low W content was prepared by liquid phase sintering. A new in-situ dissolution-precipitation process for tungsten alloys with a low W content was identified, which is different from that for tungsten alloys with a high W content. The interface between ultrafine precipitated W grains and the γ(FeNi3, W) phase in tungsten alloys with a low W content was a semi-coherent interphase boundary. Ni atoms and Fe atoms in the γ phase lattice were continuously replaced by W atoms during precipitation. W atoms continued to mass transfer to the interface area, and W grains formed when the enrichment was sufficient. The obtained 50W-25Ni-25Fe tungsten alloy had the superior combination of ultimate tensile strength (UTS) and elongation. The precipitation of ultrafine W grain strengthened the alloy.

Mg Corrosion—Recent Progress

Abstract: Recent progress is reviewed. Recent developments include: (i) accumulation of evidence that electrochemical measurements of the Mg corrosion rate often do not agree with the steady state Mg corrosion rate as measured by weight loss; (ii) low Fe tolerance limits are caused by heat treatment of nominally high-purity Mg and the presence of Si, (iii) the intrinsic Mg corrosion rate is 0.3 mm/y in a chloride solution as measured by weight loss, (iv) there are many Mg alloys with corrosion rates between 0.3 and 1.0 mm/y, (v) there are few Mg alloys with corrosion rates less than 0.3 mm/y, (vi) experimental evidence contradicts the enhanced catalytic activity mechanism of Mg corrosion, (vii) experiments support the uni-positive Mg+ mechanism, (viii) new compelling experimental evidence supporting the uni-positive Mg+ corrosion mechanism has been provided by electrochemical impedance spectroscopy (EIS), and (ix) the uni-positive Mg+ corrosion mechanism provides new insights for understanding the performance of Mg-air batteries and for the development of better Mg anodes.

A new anodic properties evaluation indicator for the magnesium‐based anodes of magnesium‐air batteries: The apparent valence

Abstract: Mg‐air batteries are promising energy storage systems to deal with the requirement of green usage, high energy density, and sustainable energy. This paper provides an in‐depth understanding of the energy loss mechanisms of Mg‐based anodes, followed by a proposed new anodic properties evaluation indicator, the apparent Mg valence, based on the reaction mechanism of Mg in aqueous electrolytes. The relationship between apparent Mg valence and the anodic efficiency is elucidated. The paper also provides a brief review of the discharge properties of current Mg anodes using the apparent Mg valence. Some development strategies are suggested to pave the path for the future development of advanced Mg anodes.

Preparation technology and properties of a thin anodic oxide composite film on the surface of an aluminum alloy foil

Abstract: This paper presents the process of preparing a phosphoric-acid thin anodic oxide composite film on an 18 μm aluminum alloy foil. The parameters of anodizing were adjusted to obtain a thin anodic oxide film, and then the nano-pores of the film were sealed by electrodeposited silane doped with Y3+. A dense and uniform oxide-organic composite film (called [email protected] film) with a thickness of only about 275 nm was successfully prepared. The structure, morphology, composition and corrosion resistance of the composite film were investigated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), energy spectroscopy (EDS), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray. The silanol groups of the silane reacted with the thin anodic oxide film to form Al-O-Si. The [email protected] film had a corrosion current density icorr of 9.18 × 10−9 A cm−2 and a low-frequency impedance modulus |Z|0.01 of 2.26 × 106 Ω cm2, which could provide long-term corrosion protection to the Al foil substrate. Furthermore, the influence of the Y3+ doping in silane solution on the composite film was also discussed.

Influence of Si, Cu, B, and Trace Alloying Elements on the Conductivity of the Al-Si-Cu Alloy

Abstract: The influence of Si, Cu, B, and trace alloying elements on the conductivity of aluminum die cast 12 (ADC12) alloy was investigated. The conductivity decreased linearly with increasing volume fraction of the Si phase attributed to a linear decrease of the volume of the more conductive Al phase through a rule of mixtures. The conductivity also decreased with increasing Cu content, between 0~3%. The conductivity increased with increasing B content, reached the peak at 0.02% B and thereafter decreased somewhat. The mechanism was that B reacted with the transition element in the Al phase to form boride, decreasing the transition element concentration in the Al lattice, and decreasing the lattice constant. The thermal conductivity, λ, was related to the electrical conductivity, σ, by means of λ=LTσ+λg, where L is the apparent Lorentz constant, 1.86 × 10−8; T is the absolute temperature, 293 K; λg is the lattice conductivity, 42.3 W/(m·K).

Deep Cryogenic Treatment Characteristics of a Deformation-Processed Cu-Ni-Co-Si Alloy

Abstract: This paper investigated the influence of deep cryogenic treatments (DCT) on the tensile strength, elongation to fracture and conductivity of a deformation-processed Cu-Ni-Co-Si alloy. The tensile properties were measured using a mechanical testing machine. The conductivity was evaluated using a low-resistance tester. The microstructure and precipitated phases were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), an energy dispersive spectrometer (EDS) and an X-ray diffractometer (XRD). The tensile strength, elongation to fracture and conductivity of the Cu-1.34Ni-1.02Co-0.61Si alloy before and after cold rolling at 47% reduction increased with increasing DCT time and tended to be stable at about 36 h. The microstructure became more uniform after the DCT. The grain size was refined and was smallest after DCT for 48 h. The DCT promoted the precipitation of the solid solution elements Ni, Co and Si from the Cu matrix to form many fine and evenly distributed 20–70 nm spherical second-phase particles in the grains and grain boundaries.

A review of metal-organic framework protective coatings for light metals

Abstract: ABSTRACT Corrosion of metals is a long-standing problem in many engineering fields. Recently, microporous and nanoporous materials, MOFs (metal-organic frameworks), have attracted much attention in the field of inorganic and organic chemistry. However, there are few studies on MOFs as protective coatings. This paper reviews (i) the basic structure, synthesis methods and types of MOFs, (ii) their growth patterns, (iii) research progress and functional mechanisms of MOFs in different fields (such as corrosion resistance, antibacterial and flame retardant), (iv) computational chemistry in the research field of MOFs to provide theoretical basis for designing MOFs with the best performance, determining the best synthesis conditions and operating parameters and (v) the application prospect of MOFs in the field of corrosion, and attempts to spread the application of MOFs to other fields.