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Alkali pre-treatment of the Ti6Al7Nb substrate and its impact on electrochemically deposited calcium phosphate coatings

100%

Iwaniak K. , Kaczorowski W. , Burnat B. , Grabarczyk J.

Engineering of Biomaterials

2024

tom vol. 27, no. 172

1--8

The aim of this work was to investigate the effect of alkali pre-treatment of a Ti6Al7Nb substrate on the morphology and physicochemical properties of calcium phosphate (CaP) coatings. CaP coatings were electrochemically deposited on two groups of substrates: one unmodified and the other pre-treated in a 5M NaOH solution. CaP coatings deposition was performed in a three-electrode system using a potentiostatic mode at a potential of -4 V for 1 h in an electrolyte containing 0.042M Ca(NO3)2 and 0.025M NH4H2PO4. The surface characteristics of the coatings were determined using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and contact angle techniques. Additionally, the corrosion resistance of the coatings was assessed by linear polarization resistance and potentiodynamic polarization tests in PBS solution. Morphological analysis showed that the coatings exhibited no significant differences. EDS analysis confirmed the presence of characteristic elements constituting the CaP coatings in both tested groups. Raman spectra revealed the characteristic peaks of the hydroxyapatite (HAp), amorphous calcium phosphate (ACP), and dicalcium phosphate dihydrate (DCPD) structures. Furthermore, Raman mapping confirmed the effectiveness of substrate pre-treatment, leading to the crystalline structure of the coatings. The water contact angle values indicated that pre-treatment of the substrate in NaOH increases the hydrophilicity of the deposited coatings. Regardless of the substrate preparation method, the deposited CaP coatings exhibited protective properties against corrosion under physiological conditions. The results confirmed that alkali pre-treatment of the Ti6Al7Nb alloy affects the crystallinity and the wettability of the electrodeposited CaP coatings.

Assessment of the properties of HAp micropowders after ion exchange process in silver nitrate solution

88%

Głuszek M. , Świrska Z. , Kaczorowski W. , Januszewicz B. , Wrotniak M.

Engineering of Biomaterials

2021

tom Vol. 24, no. 161

15--20

Bioceramic materials, such as hydroxyapatite (HAp), are characterized by high biocompatibility in the presence of tissues and body fluids without causing toxic or allergic reactions. Hydroxyapatite, due to its similarity to structures found in bones, is used both in the form of powders, e.g. as additives to bone cements, and implants coatings. However, this material is not characterized by antimicrobial properties, therefore attempts are made to improve its properties by introducing additional elements into the hydroxyapatite structure. Thanks to HAp’s high ion-exchange ability, silver can be introduced into its structure. The calcium ions present in the HAp structure can be easily replaced by silver ions to create a material endowed with high biocompatibility and antibacterial properties. The presented study is based on the analysis of the morphology of the modified powders via scanning electron microscopy (SEM), their chemical composition via X-ray energy dispersive spectroscopy (EDS) and chemical structure via X-ray diffraction (XRD) and Raman spectroscopy. The powders obtained through the ion exchange were mixtures of silver phosphates Ag3PO4 and HAp. The highest silver content was found in the sample modified with a 1M concentration of AgNO3 in the aqueous solution. It was also determined that the annealing of the obtained powders under vacuum at 800°C resulted in the formation of metallic silver and a change in the structure of HAp to β-TCP.

An experimental device for evaluation of hydrogen sorption

75%

Leyko J. , Surmiński K. , Batory D. , Jastrzębski K. , Kaczmarek Ł. , Kaczorowski W. , Kula P.

tom Vol. 30, nr 2

367--376

Hydrogen storage for the purposes of the automotive industry in a form other than under high pressure or cryo conditions has been under careful investigation by researchers over past decades. One of the arising methods is the usage of powdered/granulated beds that contain metal hydrides and/or carbon materials to take advantage of the “spillover” phenomenon. Handling and characterization of such material can be troublesome, which is why the experimental setup needs careful investigation. The apparatus for the analysis of hydrogen sorption/desorption characteristics has been successfully designed and described based on the constructed unit within the scope of this article. The full functionality of that setup covered fuelling the bed as well as the examination of sorption/desorption potential. Moreover, the proposed experimental device can clarify many uncertainties about further development and optimization of hydrogen storage materials.