Beatriz Mingo

The University of Manchester · School of Materials

Zinc aluminium (Zn-Al) and lithium aluminium (Li-Al) – layered double hydroxides (LDH) coatings with incorporated inhibitors (Li−, Mo− and W−based) were successfully synthesized on AZ31 Mg alloy. Zn−Al LDH W and Li−Al LDH Li showed the highest corrosion resistance and were selected for further evaluation. SEM cross−section examination revealed a bi...

The influence of current and frequency on energy consumption of plasma electrolytic oxidation (PEO) of a commercial aluminium alloy pre-treated by conventional anodizing in sulphuric acid has been investigated. The combination of a 20-μm thick precursor anodic porous film, high current (500 mA cm⁻²) and frequency (400 Hz) during PEO enables up to 7...

The increasing demand for magnesium-based materials for transportation has led to the development of surface treatments to enhance their performance. Active coatings stand out due to their ability to provide on-demand functionalities such as corrosion inhibition or self-healing. The current outlook on smart protection methods is dominated by organi...

Mg2SiO4 coatings were formed on cp-Mg by Plasma Electrolytic Oxidation (PEO) using electrical regimes based on sawtooth anodic current pulses with extended ascending or descending segments (ramps). Voltage, current and light emission signals were simultaneously acquired to derive and analyse the evolution of system current and discharge population...

A significant reduction in the energy consumption of Plasma Electrolytic Oxidation (PEO) coatings on AA6082 alloy was obtained using strategies based on electrolyte selection and a precursor anodic film. PEO coatings were developed on AA6082 in silicate-based electrolytes with different phosphate species without and with a precursor oxide layer. Th...

The demand of modern technological society for light structural materials (Al, Ti, Mg) emphasizes a combination of good corrosion resistance with wear properties and functionalized surfaces. Their extensive field of applications ranges from mechanical aspects and transport components to bioengineering. Regardless of the final application, improved...

Magnesium has shown great potential for the next generation of resorbable implant materials. It has well biocompatibility and biodegradability, high strength-to-weight ratio and stiffness similar to that of the human bone. However, magnesium exhibits poor corrosion behaviour, leading to the early deterioration of the implant. Therefore, appropriate...

Providing materials with smart functionalities such as self-healing properties is primarily a domain for organic materials, although their applicability is restricted to mild environments and loads due to poor thermal and mechanical properties. This work seeks to achieve the active functionalities obtained in organic materials but in ceramics, whic...

Biodegradation studies of Mg-1Ca alloy with different microstructures in Ringer’s solution reveal corrosion mechanism based on the balance between the anodic dissolution of the secondary phase and hydroxide precipitation, controlled by the secondary phase size and distribution uniformity. Alloy with ultrafine-grain structure shows at least 5-fold i...

The effect of Ca additions on the microstructure and corrosion resistance of Mg–9Al and Mg–9Al-0.5Mn alloys is investigated. Model alloys were used instead of a commercial AZ91 alloy in order to avoid masking effects from other alloying elements. Grain size and secondary phases were characterised with special interest in their Volta potential. Corr...

Bioactive Plasma Electrolytic Oxidation (PEO) coatings enriched in Ca, P and F were developed on Mg0.6Ca and Mg0.6Ca2Ag alloys with the aim to impede their fast degradation rate. Different characterization techniques (SEM, TEM, EDX, SKPFM, XRD) were used to analyze the surface characteristics and chemical composition of the bulk and/or coated mater...

This work investigates environmentally friendly alternatives to toxic and carcinogenic Cr (VI)-based surface treatments for aluminium alloys. It is focused on multifunctional thin or flash plasma electrolytic oxidation (PEO)-layered double hydroxides (LDH) coatings. Three PEO coatings developed under a current-controlled mode based on aluminate, si...

The increasing demand for high-performance lightweight metallic materials is driving an interest in Plasma Electrolytic Oxidation (PEO) as one of the most promising techniques for surface engineering of Mg. In order to enable smart and multifunctional performance, it can be beneficial to incorporate into ceramic PEO coatings nanocontainers to carry...

The microstructures of as-cast ZK40, ZK40 with 2% (mass fraction) CaO and ZK40 with 1% (mass fraction) Y were investigated, and the intermetallic phase morphology and the distribution were characterised. By having discrete intermetallic particles at the grain boundaries for the ZK40, the microstructure was modified to a semi-continuous network of i...

Composite ceramic coatings were formed on a magnesium alloy by AC plasma electrolytic oxidation using a phosphate-based electrolyte with α-Al2O3, monoclinic ZrO2 or CeO2 particles in suspension. Effects of particles concentration (2, 5 and 10 g/L) on the electrical response, composition/morphology and corrosion behaviour of the coatings were invest...

The effect of three different post-treatments carried out on Plasma Electrolytic Oxidation (PEO) coated magnesium alloys are evaluated in terms of characterisation and corrosion resistance. Special interest is given to the role of a common additive (NaF) to the coating properties. The post–treatments are based on immersion sealing processes in aque...

Plasma electrolytic oxidation (PEO) coatings developed under voltage-controlled mode on various commercial wrought, gravity cast and rheocast aluminium alloys were discussed with respect to enhancement of their tribological and corrosion performance and minimization of the PEO energy consumption. It is demonstrated that use of conventional porous a...

Microstructure and corrosion behaviour of a Mg-9Al alloy with minor alloying additions (Mn, Y, Nd, Ca and Sn) are evaluated. All of the additions form Al-rich intermetallics with varying amounts of Fe, while Ca and Sn are also incorporated into the eutectic β-phase (β-Mg17Al12). Special attention is given to the surface potential values of the micr...

The present work reports on PEO coatings which can be potentially used for degradation control of Mg-based implant materials. Three coatings were developed on Mg-0.8wt%Ca alloy: two in an electrolyte with fluoride species using different treatment times and one in a fluoride-free electrolyte. Uncoated and coated materials were examined in terms of...

Four binary cast Mg-Ga alloys containing 1, 2, 3 and 4 wt% Ga were studied in terms of microstructure and degradation behavior. The alloys present two types of intermetallics: (i) the second phase Mg5Ga2, which volume increases with the amount of Ga in the alloy, and (ii) inclusions containing impurities. For the first time, the binary Mg-Ga system...

The necessity of an adequate scientific literacy among the population in general and students in particular is a fact. Two of the main obstacles in science education that hinder it are the lack of connection between the contents worked in class and the students' day-to-day, and the misunderstanding of scientific language. In the present study, a ca...

In this work, corrosion and wear resistance of uncoated and PEO coated AZ91/SiC/0-10p composites manufactured by semisolid processing is evaluated by corrosion tests in saline solution and ball-on-disc tests. AZ91/SiC composites show a globular microstructure with SiC clusters located at the interglobular regions. PEO coatings reveal a trilayered s...

The present work describes the characteristics of 5–10 μm-thick plasma electrolytic oxidation (PEO) coatings with graded Ca/P ratio generated on titanium of commercial grades I (c.p. Ti) and V (Ti6Al4V) and some of the aspects of their bioactivity and corrosion resistance in vitro in long-term (up to 8 weeks) normal and short-term (1 week) inflamma...

Long-term effect of plasma electrolytic oxidation (PEO) coatings on in vitro corrosion of 3D Mg implant specimens has been investigated in simulated body fluid (SBF). Hydrogen evolution rate in PEO-coated specimens was 35 times lower compared to the non-coated alloy during first 2 weeks of immersion (0.04-0.07 mL cm−2 d−1) and reached a steady-stat...

In the present study, the effect of heat treatment T6.1 on the microstructure and corrosion behaviour of rheocast aluminium alloy A356 is investigated on the basis of 2D/3D characterization techniques and electrochemical and SKPFM measurements. Heat treatment strengthens the α-Al matrix, modifies the intermetallic particles and spheroidizes eutecti...

Protein release potential of plasma electrolytic oxidation coatings formed on commercially pure titaniumdirectly loaded with bovine serum albumin was investigated. Four types of coatings with thicknesses of 5 and 15 μm, graded porosity, roughness and composition were studied. The TiO2 coatings were enriched with calcium (3.7-11.1 at.%) and phosphor...

PEO coatings were developed under voltage-controlled mode on a rheocast A356 aluminum alloy without and with pretreatment by conventional anodizing in sulphuric acid. Microstructure and composition of uncoated and coated materials were studied using SEM, EDS and XRD. The anodic precursor oxide layer preserves the microstructure of the alloy because...

Rheocast AZ91 magnesium alloy was evaluated in terms of microstructure and corrosion resistance. Rheocasting leads to a globular microstructure of α-Mg spheres separated by an interconnected β-Mg17Al12 (β-phase) network. Findings revealed that early stages of corrosion were located at the center of α-Mg globules and more importantly at α-Mg/β-phase...

The effect of copper on anodising of aluminium in sulphuric acid at low potentials has been examined for a sputtering-deposited Al–0·75 at.-%Cu alloy, using ion beam analysis and transmission electron microscopy. The aim was to determine the relationship between the potential and oxygen generation, with copper in the anodic film in either a metalli...

Plasma electrolytic oxidation (PEO) coatings with incorporated α-Al2O3 particles were formed on 6082-T6 alloy. Effects of particle concentration on phase composition and wear behaviour were investigated. Tribological performance was compared with that of electrolytic hard chrome. Results suggested that α-Al2O3 particles are incorporated into the ou...

The influence of pre-anodising in sulphuric and phosphoric acids on energy efficiency of voltage-controlled PEO process of three commercial wrought and cast aluminium alloys (AA1050, AA6082 and A356) has been investigated. The precursor anodic porous films enable up to 57% energy savings during PEO and produce ~35–40% increase of the coating microh...

The microstructure of a gravity-cast A356 aluminium alloy modified with 0.4 wt% Nd and its corrosion behaviour in 3.5 wt% NaCl solution is investigated. The addition of Nd refines the eutectic silicon and results in the formation of Nd-containing intermetallics, which show smaller potential differences relative to the α-Al matrix than the Fe-rich i...

Electrochemical and gravimetric measurements were used to examine the effects of neodymium and gadolinium additions on the galvanic corrosion behaviour of AM50 and AZ91D magnesium alloys coupled to A 570 Gr 36 carbon steel and AA2011-AA6082 aluminium alloys. Rare earth modified alloys showed Al 2Nd/Al2Gd and Al-Mn-Nd/Al-Mn-Gd intermetallics, reduce...

In this study, the microstructure and corrosion behaviour of rheocast and gravity-cast A356 aluminium alloys were examined and compared. Scanning Kelvin probe force microscopy (SKPFM) results proved that large potential differences between iron-containing intermetallics and the α-Al matrix were responsible for the initiation of the attack at the in...